7 F CI,Br I At and Noble Gases By J. M. WINFIELD Department of Chemistry University of Glasgow Glasgow GI2 8QQ 1 Introduction Surface enhanced Raman scattering (SERS) from electrogenerated chlorine on a Pt electrode has been interpreted in terms of the formation of both linear (1) and bridged (2) or (3) adsorbed Clz species.'" Adsorbed I2 and I,-species have been detected on Pt and Pd metals by a similar technique.lb C1 I C1 I C1 IPt Pt \Pt The weak bond in F2 has a profound influence on its chemistry and has usually been accounted for by postulating high lone-pair-lone-pair repulsion in the molecule. Core and valence ionization potentials of this and related molecules have been used to evaluate the ionization potentials that atomic orbitals in molecules would have if they were non-bonding.Comparison between these and experimentally derived T and T* ionization potentials provides strong evidence for lone-pair repulsion in F2 and possibly also in ClF. Such repulsion is absent in C12 Br I, IC1 and IBr.' 2 Interhalogens and Related Ions Reactions which occur between I2 and good Lewis bases (B) have been widely studied one reason being that they often result in equilibria involving the ions B21+ and I,-. These and other aspects of I' co-ordination chemistry have been re~iewed;~" they feature also in a review of the electrochemistry of iodine.3b The electrochemistry of 1-/13- and I-/Iz redox processes is complicated by adsorption (cj rej 16) and universally accepted explanations of observed electrochemical phenomena are still not available.Formation of B2X+ (X = C1 or Br) cations in solution has been postulated although these halogens have been less well studied than has 12. However the Raman spectra of CI and Br solutions in N,N-disubstituted amide solvents ' (a) B. H. Loo,J. fhys. Chem. 1983 87 3003; (b)Solid State Commun. 1982 43 349. W. L. Jolly and C. J. Eyermann,'Inorg. Chem. 1983 22 1566. (a) Yu. N. Kukushkin and V. N. Demidov Koord. Khim. 1983,9 1299; (b) Ya. A. Yaraliev Russ. Chem. Rev. (Engl. Trans[.) 1982 51. 566. 143 144 J. M. Winjield indicate that X3- and so presumably solvated X+ are present,4a and bis(quinu- clidine) brcmine(1) has been isolated as its BF,- salt (4).4h Its X-ray crystal structure shows that the N-Br-N moiety is linear.I2 is oxidized by MoF in MeCN to give the I(NCMe),+ cation which is isolated as the MoF,- salt. A linear N-I-N skeleton is suggested from its vibrational spe~trum.~ Most of the reports on astatine in this period focus on its similarity to iodine. Formation constants of AtX2- (X = Br I CN or SCN) have been determined in acidic aqueous solution by electromigration methods.6a At1,- is stable to pH 12 whereas AtX2- (X = C1 Br or SCN) under these conditions are reduced to At-. Cationic complexes of At' with thiourea or its substituted derivatives have been identified in aqueous solution,6h and (H,O)Atf is believed to be the active species in astatobenzene formation from C6H6 and At in aqueous acid.6" An electron diffraction study of BrF vapour indicates that it has the expected T-shaped structure like ClF3,7U and the structures of halogen fluorides and oxo-fluorides have been reviewed.7h Complex formation is a characteristic of BrF, and several of its adducts with the fluorides of RlV,Sn'" IrV and Au"' have been studied in the solid state by I9F n.m.r.spectroscopy. Ionic structures are postulated in each case.8 The ability of BrF2' CIF2+ or BrF,+ to fluorinate aromatic fluorine compounds has been demonstrated. For example perfluorocyclohexa- 1,4-diene is formed from C6F6 and BrF,SbF,. The cations are more reactive in this respect than the parent halogen fluorides.' Other salts containing triatomic halogen cations which have been fully characterized this year include [IBr2][Sb2F ,I prepared from IBr and SbF in SO2 and [IBro.75CII.25][SbC16] in which the cation is disordered and which is prepared from IBr SbCI, and C12 in the same solvent.Their X-ray crystal structures indicate that both cations are bent bond angles at I are 100.0" and 97.7"respectively the cation-anion arrangement being such that I"' has a trapezoidal four-co-ordina- tion involving two cis-bridges (I-.Y-Z) to the anions (5). The I2'I Mossbauer spectra of these compounds are dominated by the primary bonds to I"' which are largely of p character." (a) M. De Meyer J. M. Levert and A. Vanclef Bull. SOC. Chim. Belg. 1983 92 347; (b) L. K. Blair K. D. Parris P. S. Hii and C. P. Brock J. Am. Chem. Soc.. 1983 105 3649. ' G. M. Anderson 1. F. Fraser and J.M. Winfieid J. Fluorine C'hem. 1983 23 403. '(a)R. Dreyer I. Dreyer F. Rosch and G.-J. Beyer Radiochem. Radioanal. Lett. 1982 54 165; R. Dreyer I. Dreyer M. Heiffer and F. Rosch ibid. 1983,554 207; (b)R. Dreyer I. Dreyer F. Rosch and S. Fischer Z. Chem. 1983 23 346; (c) L. Vasaros Yu.V. Norseyev D. D. Nhan and V. A. Khalkin Radiochem. Radioanal. Lett. 1982 54 239. ' (a)A. A. Ishchenko I. N. Myakshin G. V. Romanov V. P. Spiridonov and V. F. Sukhoverkhov Dokl. Akad. Nauk SSSR 1982 267 1143; (b) Yu. A. Buslaev V. F. Sukhoverkhov and N. M. Klimenko Koord. Khim. 1983 9 101 I. V. N. Mit'kin Y. I. Mironov S. V. Zemskov B. D. Zil'berman and S. P. Gabuda Koord. Khim. 1983 9 20. V. V. Bardin G. G. Furin and G. G. Yakobson J. Fluorine Chem. 1983 23 67. T. Birchall and R.D.Myers Inorg. Chem. 1983 22 1751 J. Chem. Soc. Dalton Trans. 1983 885. F Cl Br I At and Noble Gases /--. X y Z (5) CI3+ and Br3+ are among the products observed in the low temperature (12 K) Raman spectra of N02,HX (X = C1 or Br) mixtures which have been equilibrated at room temperature for 1h. Formation of C1,+ is suggested to occur via the reactions C12 +C1N02 and C12 +ClN03." The I:+ cation has been fully characterized in two salts red 14(ASF6)2 and black 14(Sb3F1,)(SbF,). Both are prepared by oxidation of I2 with the appropriate pentafluoride in SO2.The cation is rectangular (Figure 1) and can be described as two I,+ cations held together by two relatively weak bonds." A similar conclusion was reached from a Mossbauer study reported last year.F Figure 1 One ofthe cations from I,(SbF,)(Sb3F,,). The bond lengths (A) and angles (") are listed in orderfor the cation in I,(AsF,) and the two carions in I,(SbF,)(Sb3F,,) (Reproduced from J. Chem. SOC.,Chem. Commun. 1983 8) Considerable progress has been made in the preparation and characterization of ClF6+ salts. The AsF6-salt is prepared by oxidizing CIF with KrFAsF,,l3" and the BF4- salt by low-temperature metathesis in anhydrous HF from CIF6AsF6.'3h The compounds' spectra are in accord with the presence of octahedral cations. ClF,+ can be compared with NF,+ as both cations are co-ordinatively saturated. A report describing the preparation of (C1F6)(CUF4) has been shown to be incorrect. In reality the compound isolated was [CU(H,0),][SiF6].'4 " L.-H.Chen. E. M. Nour and J. Laane J. Raman Specfrosc. 1983 14 232. R. J. Gillespie R. Kapoor R. Faggiani C. J. L. Lock M. Murchie and J. Passmore J. Chem. SOC. Chern. Commun. 1983 8. l3 (a) K. 0.Christe W. W. Wilson and E. C. Curtis Znorg. Chem. 1983 22 3056; (b)K. 0.Christe and W. W. Wilson ibid. p. 1950. l4 H. G. Von Schnering and Dong Vu Angew. Chern.. Int. Ed. EngL 1983 22 408. 146 J. M.Winjield Phenyliodine(II1) carboxylates are widely used reagents in organic chemistry and this interest has been extended to perfluoro-analogues. The crystal structure of C6F51[OC(0)C6F,] shows the presence of distorted T-shaped molecules which have weak intermolecular contact^.'^ The reactions of aryliodine(Ir1) or aryliodine(v) fluorides with PhSO,N(SiMe3) lead to the phenylsulphonylimino-derivatives Ar1=NSO2Ph and ArI( =NS02Ph)2.'6 Several chelated hydroxycarboxylic acid derivatives of IF5 for example IF,[OC(O)CH,O] have been identified in solution by 19F n.m.r.spectroscopy. Axial-equatorial chelation around the square pyramidal I" centre is the preferred co-ordination mode." 3 Noble Gas Compounds Cr(CO),Xe has been identified by i.r. spectroscopy as a relatively long-lived ti = ca. 2s at 175 K species following U.V. photolysis of Cr(CO) in liquid Xe.18 This element is also useful as a cryogenic solvent for uranium halides. The u.v.-visible spectrum of UC1 has been obtained in liquid Xe ca. 163 K,I9' and i.r. spectra assigned to UF,-,Cl mixtures have been observed under similar condition^.'^' The v3 vibra-tional band of UF obtained from a frozen solution in Xe consists of a single sharp feature,'" and there is no evidence for multiple trapping-site effects characteristi- cally observed in deposition matrix spectra.The conversion CH3S- into CH2FS- in methionine and methionylglycine deriva- tives is readily achieved using XeF in MeCN at or below room temperature,200 and a high yield synthesis of 2-['8F]fluoro-2-deoxy-~-glucose using Xe * 'FF and BF3,0Et2 as catalyst has been reported by two groups.20b This "F-labelled compound is a potential brain scanning agent in positron emission transaxial tomography (See also Section 5). The oxidative fluorinating abilities of Xe fluorides and KrF have been exploited in syntheses of tetravalent lanthanides LnF (Ln = Ce Pr or Tb) and Cs3LnF7 (Ln = Ce Pr Nd Tb Dy or Tm).The thermally unstable PrF is accessible only using KrF2.21 Physico-chemical studies involving Xe fluorides continue to be reported. The fusion and boiling points of XeF are 409 f5 K and ca. 61 1 K respectively the enthalpy of fusion being 14.04 f2.09 kJ mol-I. Disproportionation of XeF to XeF + Xe is observed above 623K.22a The activation energy for the reaction of Xe with O,SbF to give FXeSb,F, and O2 has been determined as 71.1 f 8.4kJmol-'.22b X-Ray P.E. spectra of core levels of KrF and Xe fluorides have been obtained,23 including satellite spectra assigned with the aid of Xa calculations H. J. Frohn J. Helber and A. Richter Chem.-Ztg. 1983 107 169. l6 I.I. Maletina A. A. Mironova V. V. Orda and L. M. Yagupolskii "wiis 1983 456. l7 Y. V. Kokunov S. A. Sharkov and Yu. A. Buslaev Koord. Khim. 1983 9 912. '* M. B. Simpson M. Poliakoff J. J. Turner W. B. Maier 11 and J. G. McLaughlin J. Chern. SOC. Chem. Commun. 1983 1355. 19 (a)W. B. Maier 11 R. F. Holland and W. H. Beattie Spectrosc. Lett. 1983 16 233; (b)W. €3. Maier 11 W. H. Beattie and R. F. Holland J. Chem. SOC.,Chem. Commun. 1983 598; (c)R. F. Holland and W. B. Maier 11 Spectrosc. Lett. 1983 16 409. 2o (a)A. F. Janzen P. M. C. Wang and A. E. Lemire J. Fluorine Chem. 1983 22 557; (b)S. Sood G. Firnau and E. S. Garnett Int. J. Appl. Radial. Isot. 1983 34 743; C.-Y. Shiue K.-C. To and A. P. Wolf J. Labelled Comp. Radiopharm. 1983 20 157. *' V. I.Spitzin L. I. Martynenko and Ju. M. Kiselew 2. Anorg. Allg. Chem. 1982 495 39. 22 (a)Yu. M. Kiselev and S. A. Goryachenkov Russ. J. Inorg. Chem. (Engl. Transl.) 1983 28 9; (b)A. B. Myasoedov L. N. Nikolenko and L. D. Shustov ibid. 1982 27 892. F Cl Br I At and Noble Gases 147 to monopole-allowed shake-up transitions. The calculated energy of the KrF2 ground state is in good agreement with the experimental valence-band energies.23ff Vibra- tional broadening observed in the F 1s spectra has been correlated with the dissoci- ation energy for the reaction XNe+ + X+ + Ne X = KrF XeF etc. enabling relative Lewis acidities towards Ne to be obtained.23b XeF reacts with NF4HF2 in anhydrous HF to give NF,XeF which undergoes laser photolysis at 488 nm giving (NF4),XeFs.The vibrational spectra of both compounds and those of the Cs+ salts have been obtained and evidence for the existence of NaXeF has been AH; for NF,XeF,(s) is calculated to be -490.7 kJ mol-' from a DSC study of its decomposition and the compound is by far the most energetic of known NF,+ salts.,,' Further spectroscopic information has been published on Xe[N(SO,F),] which as was reported last year contains Xe-N bonds. The data include "N n.m.r. measurements and a low-temperature Raman The chemistry of radon has been reviewed including the formation of clathrate compounds simple and complex fluorides solutions of ionic radon redox properties of Rn compounds and the unsuccessful attempts to prepare an oxide and halides other than the fluoride.26 4 Hydrogen Halides A new model for the self-association of HF vapour in the temperature range 299-329 K has been proposed from a re-examination of previously obtained P-V-T data.27 It consists of monomer trimer and hexamer species; the model differs somewhat from one reported in last year's Report which included species up to (HF),,.A new structural model for liquid HF has been proposed from a study in which the experimental vibrational spectra of HF DF and their mixtures were compared with spectra calculated on the basis of various hypothetical structures. The best fit for HF at 293 K is with a zigzag chain containing six or seven molecules having an angle of 42" with the average axis. Near to solidification at 190K eight-molecule chains with an angle of ca.35" are proposed.28 A third approach to the structural chemistry of HF is illustrated by a matrix isolation study using FT i.r. spectroscopic analysis.29 Co-condensation of HF and Ar at 12 K results in a number of bands in addition to that ascribed to the HF monomer. The different growth behaviour observed on sample warming coupled with experiments involving HF-DF mixtures enable convincing assignments to be made. Species identified include (HF) (6) for which (7) is the more stable isotopomer in the HF-DF system in agreement with previous microwave work and (HF) for which an open trans structure (8) is suggested. Open and cyclic (HF) and cyclic (HF) (n = 5 or 6) are probably present also. 23 (a) G. M. Bancroft D. J. Bristow J.S. Tse and G. J. Schrobilgen Znorg. Chem. 1983,22,2673; (b)D. J. Bristow and G. M. Bancroft J. Am. Chem. Soc,1983 105 5634. 24 (a)K. 0.Christe and W. W. Wilson Znorg. Chem. 1982,21 4113; (b)K. 0.Christe W. W. Wilson R. D. Wilson R. Bougon and T. Bui Huy,J. Fluorine Chem. 1983 23 399. " G. A. Schumacher and G. J. Schrobilgen Znorg. Chem. 1983 22 2178. 26 L. Stein Radiochim. Acta 1983 32 163. 27 J. M. Beckerdite D. R. Powell and E. T. Adams Jr. J. Chem. Eng. Data 1983 28 287. 28 B. Desbat and P. V. Huong J. Chem. Phys. 1983 78 6377. 29 L. Andrews and G. L. Johnson Chem. Phys. Lett. 1983 96,133. J. M. Winjield (6) (7) (8) 1.r. spectroscopy has made a significant contribution to our knowledge of hydro-gen-bonded base...HX (X = F C1 or Br) complexes both in the gas phase and in matrix-isolated species and recent progress has been re~iewed.~' Results obtained from Ar-matrix isolation studies are complementary to those from gas-phase work using other techniques e.g.FT microwave spectroscopy (see 198 1 and 1982 Reports) but in addition to 1 :1 complexes base.-.(HX) species are often observed on warming the matrix to ca. 20 K. Thus the species base...(HF) (base = N2 OC or H20),31a*b,c MeCN...(HX) (X = For C1) and MeCN.-(HF),3'd have been observed. Open structures are postulated for the base...(HX) complexes. The isomers (9) and (10) are both produced when HCN and HF are co-condensed with Ar at 12 K.32 H-F H-CE N--H-F H \ C* N The proportion of (9) increases at the expense of (10) on warming to 20 K in agreement with it being the more stable isomer.It is linear as has been previously shown in the gas phase but the other isomer may be non-linear. Only one isomer analogous to (9) appears to be formed from HCl and HCN under similar conditions. The complex CO--HF has not so far been observed although its C-bonded isomer is well established both in the gas phase and in a matrix (cf ref 3 1b). Theoretical work suggests that its energy is >400cm-I above that of OC.-.HF as a result of differences in electron-correlation energies.33 Hg. -HCl has been observed in the gas phase using FT microwave spectroscopy. The Hg...Cl distance is 4.097 % from which a van der Waals radius for Hg of 1.99 8 has been derived.34 This is within the range previously proposed from crystallographic work.5 Oxo-compounds Recent progress in the chemistry of inorganic and organic fluorinated hypofluorites and hypochlorites has been reviewed,35 and a new addition to this type of compound is TeF,OF prepared from FOS02F and CST~F,~.~~ ["F]MeC(O)F prepared in situ 30 A. J. Barnes J. Mol. Struct. 1983 100 259; L. Andrews ibid. p. 281. 31 (a)L. Andrews B. J. Kelsall and R. T. Arlinghaus J. Chem. Phys. 1983,79 2488; (b)L. Andrews R. T. Arlinghaus and G. L. Johnson ibid. 1983 78 6347; (c)L. Andrews and G. L. Johnson ibid. 1983 79 3670; (d)G.L. Johnson and L. Andrews J. Phys. Chem. 1983,87 1852. 32 G. L. Johnson and L. Andrews J. Am. Chem. SOC.,1983 105 163. 33 M. A. Benzel and C. E. Dykstra Chem.Phys. 1983 80 273. 34 E. J. Campbell and J. A. Shea J. Chem. Phys. 1983,79 4082. 35 J. M. Shreeve Ado. Znorg. Chem. Radiochem. 1983 26 119. 36 C. J. Schack W. W. Wilson and K. 0. Christe Inorg. Chem. 1983 22 18. F Cl Br I At and Noble Gases 149 from ''FF and NaOC(0)Me in glacial acetic acid has been used to prepare labelled 2-fluoro-2-deoxy-~-glucose~~ ref 20b). (cf Compounds containing the -OF group are often stated to be sources of 'positive' fluorine. The evidence for this in the light of recent synthetic work involving these compounds has been evaluated and found wanting.3Mu For example the products obtained from reactions between CF30F and simple alkenes suggest that the reac- tions occur via free-radical rather than by electrophilic syn-addition mechani~rns.~~ Rates of formation of N-bromoamines from OBr-or HOBr and various nitrogeneous compounds at pH 7-1 3 have been determined by stopped-flow methods.In the mechanism suggested HOBr and OBr- react simultaneously with the free amine base with electrophilic attack at N.39a The reaction of HOCl with NHC12 in aqueous solution to give NCI is base-catalysed the base assisting removal of H+ from NHC12 as the N attacks the C1 atom of HOC1. Additional HOCl is generated from the reaction between NC1 and NHCI2. The overall reaction of NHC12 is inhibited by NH3 because of preferential reaction between NH3 and ~0~1.3~~ The i.r. spectrum of matrix-isolated CsClO shows the presence of tridentate interaction between Cs+ and C103-.40 Anhydrous Zn(CIO,) appears from its vibra- tional spectrum to be polymeric and to contain bridging tridentate CIO groups.The compound is prepared by the thermal decomposition of orange C102Zn(C10,), which in turn is prepared from Zn and C1206.41 The Raman specta of KX04 (X = C1 or Br) in anhydrous HF show that both ions are partially protonated. HBrO has six times the acid strength of HCIO,; its dissociation constant in aqueous solution is estimated to be and its Hammett acidity function is estimated as ca. -13.8.42 H5106 1 mol dm- in conc. H2S04 has been used in a one-pot synthesis of C616 from C,H,; C6H5103 is a possible intermediate.43 The compound C10N02 continues to attract considerable attention no doubt in part due to its relevance in stratospheric chemistry.Mention of a possible reaction between CION02 and C12 to give C13+ has already been made." The kinetics of the reaction CI' + C10N02+CI2 + NO3' have been re-investigated. The reaction occurs about 50-times faster than was previously Three groups have independently established that the major U.V. photolytic decomposition of C10N02 gives CI' and NO3' as primary products.44",'*d The far-i.r. torsional spectrum of C1ONO2 has been re-examined at very high resolution and is interpreted in terms of a single planar r~tamer.,~ This is in agreement with the microwave study and with some of the previously reported vibrational spectroscopic studies. Evidence 37 M. Diksic and D. Jolly Inf. J. Appl. Radiaf. fsof. 1983 34 893. 38 (a)K.0.Christe J. Fluorine Chem. 1983,22,519;(6) K. K. Johri and D. D. DesMarteau J. Org. Chem. 1983 48 242. 39 (a)J. E. Wajon and J. C. Morris Inorg. Chem. 1982 21 4258; (b)V. C. Hand and D. W. Margerum ibid. 1983 22 1449. 40 1. R. Beattie and J. E. Parkinson J. Chem. SOC. Dalton Trans. 1983 1185. 4' J.-L. Pascal J. Potier and C. S. Zhang C. R. Hebd. Seances Acad. Sci. Ser. 11 1982 295 1097. 42 L. Stein and E. H. Appelman Inorg. Chem. 1983 22 3017. 43 L. S. Levitt and R. Iglesias J. Org. Chem. 1982 47 4770. See also D. L. Mattern ibid. 1983 48 4772. 44 (a)J. J. Margitan J. Phys. Chem. 1983 87 674; (b)M. J. Kurylo G. L. Knable and J. L. Murphy Chem. Phys. Leu. 1983 95 9; (c)W. J. Marinelli and H. S. Johnston ibid. 1982 93 127; (d)H.-D. Knauth and R.N. Schindler 2. Nafurforsch. Ted A 1983 38 893. 45 K. V. Chance and W. A. Traub J. Mol. Spectrosc. 1982 95 306. 150 J. M. Winjield for the presence of ClOONO in ClONO, prepared from Cl20 and N205 or by the gas-phase reaction of C10 with NO2 comes from a matrix isolation i.r. Gas-phase U.V. photolysis of C102 at room temperature using a stainless steel reaction vessel leads to ClOClO as the major product. It is not observed however when photolysis is conducted in a Pyrex Non-photochemical reactions between 02-0,mixtures and C12 below room temperature result in ClOClO CIOz or ClOClO2 depending on the condition^.^^ 6 Structural Chemistry of Solid Complex Halides Containing Main-group Elements 19 F Magic-angle spinning n.m.r. spectroscopy is a powerful technique for investigat-ing the reaction between hydroxy-apatite Ca,(OH)(PO,) and aqueous F- ion.All types of F- crystalline amorphous or adsorbed can be determined quantitatively. The growth of a surface fluoride layer when hydroxy-apatite is exposed to F-(aq.) has been demonstrated. Samples exposed to high concentrations of F-(aq.) show a signal attributable to CaF, in addition to the fluoro-apatite signal.49" Synthetic Ca,F(PO,) can be prepared from CaF and Ca3(P04)2 1 :3 mole ratio at 1933 K.49b The compounds Tl"'MF (M = Ga In or Sc) are isostructural with VF, and have a statistical distribution of metal cations in the hexagonal lattice.50a Ba2ZnAlF9 contains octahedral ZnF and AlF groups Zn" and Al"' having a statistical distribution.Four MF6 octahedra are linked to give a 'ring' system and these are connected to give This is one of three structural types which have been found for Ba2M"M"'F9 complex fluoride^.^^' Re-examination of the In/Cl phase diagram indicates that the only mixed-valence chlorides existing between InCl and InCl are In3C14 In,Cl, and In5C19. The latter compound has the Cs,Tl,Cl structure with isolated confacial bioctahedral In"',C19 groups. The preparation of solid-state compounds by chemical transport has been reviewed. In many cases gaseous halides are involved.52" An account has also been given of the gaseous ternary chloride complexes characteristically formed by MC13 (M = Al Ga In Sc or Fe"') or by UC15.52b Many of these species are effective metal-transport agents.The reaction of Ca3As2 with CaCl, 1 :3 mole ratio produces greyish-white Ca,AsCI,. This is isotypic with Mg,NF3 and its (reversible) decomposi- tion begins at 1298 K., Complex fluorides containing Sb"' have attracted considerable attention in recent years. A wide variety of co-ordination environments is possible about Sb'l' but in all cases the lone pair appears to be stereochemically active. X-Ray crystallographic 46 S. C. Bhatia M. George-Taylor C. W. Merideth and J. H. Hall Jr. J. fhys. Chem. 1983 87 1091. 47 A. J. Schell-Sorokin D. S. Bethune J. R. Lankard M. M. T. Loy and P. P. Sorokin J. fhys. Chem. 1982 86,4653. 48 R. C. Loupec and J. Potier J. Chim. fhys. fhys. Chim. Biol. 1983 80 449. 49 (a)J. P. Vesinowski and M.J.Mobley,J. Am. Chem. Soc. 1983,1M,6191;(b)E.-D. Franz,Z. Naturforsch. Ted B 1983 38 1037. 50 (a) R. Losch Ch. Hebecker and Z. Ranft 2. Anorg. Allg. Chem. 1982,491 199; (b) T. Fleischer and R. Hoppe ibid. 1982 492 83; (c)T. Fleischer and R. Hoppe ibid. 1982 493 59. " G. Meyer and R. Blachnik 2. Anorg. Allg. Chem. 1983 503 126. 52 (a) R. Gruehn and H.-J. Schweizer Angew. Chem. Znt. Ed. EngL 1983 22 82; (b) H. Sch'afer Adv. Inorg. Chem. Radiochem. 1983 26 201. 53 C. Hadenfeldt and H. 0.Vollert 2.Anorg. Allg. Chem. 1982 491 113. F Cl Br I At and Noble Gases work reported this year is illustrated by five compounds (SbF3)3SbFs,54a KSbF2(HP04),546 M'SbF(P0,).nH20 (MI = Na n = 2 3 or 4; M' = NH4 n = and NH4Sb3Flo.s4d The monoclinic 3 1 SbF3,SbF5 adduct is formed by PF3 reduction of SbF in AsF and contains SbF6- anions located between parallel strands of (Sb3F8+)ooWithin the polymeric cation Figure 2 SbF3[Sb(3),F(6),F(8)] and Sb2F5+ [Sb(2) F( l) F(3) F(7)] units can be distinguished if only the shorter inter-atomic distances are ~onsidered.~~" SbF2+ and SbF2+ cations are considered to be present in the phosphate salts with SbF2+ and SbF2+ behaving as Lewis acids towards three HP02- and four PO:- bridging ligands respectively.The co-ordina- tion environment about Sb in KSbF2(HP04) Figure 3 corresponds to a distorted octahedron if the lone pair is included. The Sb-0(2) distance is significantly longer than the other Figure 2 (Sb3F,+) strand (Reproduced from J. Chem.Soc. Dalton Trans. 1983 619) Figure 3 Co-ordination of Sb"' in KSbF,(HPO,) (Reproduced by permission from J. Solid State Chem. 1983 46 204) The Sb"' environment in the SbF2+ salts is similar to that in Figure 3 with the substitution of the equatorial F by 0.All oxygen atoms are ligated to different Sb"' atoms giving a layer structure in which F atoms are oriented alternately up and do~n.'~'' The structure of NH4Sb3Flo contains (Sb,F,,-) layers in which Sb2F7- anions and SbF3 molecules are linked.s4d The corresponding Na+ salt contains true Sb3F,,- ions. (a)W. A. S. Nandana J. Passmore D. C. N.Swindells P. Taylor P. White and J. E. Vekris J. Chem. SOC.,Dalron Trans. 1983 619; (b)S. Hurter R. Mattes and D. Ruhl J. Solid State Chern. 1983 46 204;(c) R.Mattes and K.Holz Angew. Chem. Int. Ed. Engl. 1983 22 872 Supplement p. 1315. (d)B. Ducourant R.Fourcade and G. Mascherpa Rev. Chim. Mintrale 1983 20 314. J. M. Winfield 7 Molecular Main-group Dihalides A,X2 Halides and Related Halides Structural data recently obtained for gaseous dihalides by electron diffraction are summarized in Table 1. Table 1 Bond distances and angles for some gaseous dihalides Compound (MX,) M-X (4 n XMX (") ReJ SiCl 2.083 102.8 SiBr 2.243 102.7 SnBr 2.508 100.1 SnI 2.70 1 104.1 PbF 2.030 97.2 PbBr 2.591 99.2 PbI 2.796 100.1 SeCI 2.157 99.6 a I. Hargittai G. Schultz J. Tremmel N. D. Kagramanov A. K. Maltsev and 0.M. Nefedov J. Am. Chem. SOC.,1983 105 2895; 'A. V. Demidov A. G. Gershikov E.Z. Zasorin V. P. Spiridonov and A. A. Ivanov J. Srruct. Chem. (Engl. Transl.) 1983 24 7; L. Fernhoet A. Haaland R. Seip R. Kniep and L. Korte Z. Narurforsch Teil E 1983,38 1072. The observation of matrix-isolated HSiF was reported last year and the species has now been detected in the gas phase by its laser-induced fluore~cence.~~ Low temperature X-ray work on four A2X2 (A = S or Se; X = C1 or Br) compounds indicates that the XA-AX dihedral angles are in the range 83.9-87.4". Three different crystalline modifications exist over the group owing to different ways in which the A2X2molecules are packed.56 The dimer of SF2 has the structure SF3SF. Many different conformers are possible and the precise determination of its structure is made difficult by its ready decomposition.A combined electron diffraction microwave ab initio calculation operation has provided the best information to date. The structure proposed (1 1) contains a highly distorted trigonal bipyramidal S atom. The two S-FF, bonds differ by 0.1 A and the angles between the axial bonds and the equatorial plane are ca. 77 and 92°.57 Various aspects of borons8 and tellurium59 sub-halide chemistry have been reviewed. 55 H. U.Lee and J. P. Deneufville Chem. Phys. Lett. 1983 99 394. 56 R. Kniep L. Korte and D. Mootz Z. Naturforsch. Ted B 1983 38 1. 57 M. V. Carlowitz H. Oberhammer H. Willner and J. E. Boggs J. Mol. Struct. 1983 100 161. 58 A. G. Massey Adv. Inorg. Chem. Radiochem. 1983 26 1. 59 R. Kniep and A. Rabenau Top. Curr.Chem. 1983 111; 145. F Cl Br I At and Noble Gases 8 Silicon Halides Literature values for the heats of formation of silicon-halogen compounds have been reviewed and recommended values for the compounds SiX4-,H (X = F CI or Br; n = 0 1 2 3 or 4) Six3 Six2 and Six (X = F-I) inclusive have been given. First and second bond-dissociation energies for Six have also been evalu- ated.60 Halogen lone-pair ionization potentials in a number of Group IV tetrahalides corrected for the effects of potential and relaxation energy using the corresponding halogen core-binding energies indicate that significant (p 4 d)r bonding exists. As expected the greatest lone-pair stabilization is found in SiF4.61 The structure of SiF3BF2 has been determined by microwave spectroscopy.The Si-B bond distance is 2.027 A significantly longer than expected for a single bond and the barrier to rotation about B-Si is 9.1 1 f0.02 J mol-’.62 Penta-co-ordinated species containing Si- F bonds continue to attract attention and recent work has been reviewed.63 A compound of this type is SiF4,NH3 whose structure has been assigned as a trigonal bipyramid with NH3 axial from its matrix- isolated i.r. specmm (see 1981 Report). An identical conclusion has been reached on the basis of ab initio MO calculations. From these it appears that the electron density transferred from NH to SiF originates on the H atoms. The N atom in the adduct is more negatively charged than either N in free NH or F in SiF4,NH3.64a Spectroscopically similar adducts SiF,L (L = H20 MeOH or Me20) have also been detected by matrix-isolation i.r.spectroscopy.646 A number of five-co-ordinate compounds whose stereochemistries are intermediate between trigonal bipyramidal (tbp)and square pyramidal (sp) are known; an addition to the list is the bis(tetramethylethy1enedioxy)fluorosilane anion (12). An X-ray study of the NMe,+ salt shows that the two crystallographically independent anions present are distorted from tbp towards sp by 69.1 and 52.3% re~pectively.~~ (12) (13) (14) The X-ray structure of 1-(trifluorosily1)- 1,2,3,4,-tetrahydro- 1,lO-phenantholine shows the presence of tbp Si (13) although the presence of the chelating organic group is not evident from the compound’s electronic spectrum. A chelate ligand is present also in the analogous -BF2 compound.66 Other work in this area has involved solution spectroscopic examination of (aroyloxymethyl)trifluorosilanes(14) and related compounds.Temperature solvent substituents in the ligand the pres- ence of other ligands in solution and the substitution of -F by -Me all have an 60 R. Walsh J. Chem. SOC.,Faraday Trans. 1 1983 79 2233. 61 W. L. Jolly Chem. Phys. Lett. 1983 100 546. 62 P. R. R. Langridge-Smith and A. P. Cox J. Chem. Soc. Faraday Trans. 2 1983 79 1089. 63 V. 0.Gel’mbol’dt and A. A. Ennan Sou. J. Coord. Chem. (Engl. Transl.) 1982 8 632. 64 (a)C.J. Marsden Ynorg. Chem. 1983 22 3177; (6) B. S. Auk J. Am. Chem. SOC.,1983 105 5742. 65 D. Schomburg Z. Naturforsch. Ted B 1983 38 938. 64 G.Klebe. K. Hensen and H. Fuess Chern. Ber. 1983 116 3125. 154 J. M. Winfield effect on the ability of the =C=O group to co-ordinate to Si.67 The use of a suitable chelating ligand allows the non-equivalence of the equatorial F ligands to be demonstrated by I9F n.m.r. spectroscopy at low temperatures,68a and if free radical ligands for example those derived from ortho semi-quinones are used e.p.r. spec- troscopy can be used as a probe for the stereochemistry.68b 9 Fluoro-and Perfluorocarbon-derivatives of Nitrogen 14 N n.m.r. chemical shifts of a variety of N-F cations have been obtained and have been discussed in terms of T-and a-flu~ro-effects.~~ The e.p.r. spectrum of NF3.+ is characteristic of a trigonal pyramid angle ca. 105" the N-F bonds involving sp'.' N hybrids.Thus the species differs somewhat from the isoelectronic CF,' which is essentially tetrahedral.70 The e.p.r. spectrum of CF3N(0)0C(CH3) indicates restricted rotation of the CF3- group and thus provides additional support for the postulate that alkoxylalkyl nitroxides are less planar at N than are their dialkyl analogues." Core binding energies in ONF have been interpreted on the basis of strong hyperconjugation with N-0 .rr-bonding and weak N-F a-bonding. The HOMO of ONF, derived formally from 0 p"-orbitals is weakly antibonding and has considerable F lone-pair character. Similarly the lower energy orbital derived for- mally from the N-F a-orbitals has considerable N-0 ~haracter.~, Perfluoroalkyl-ONF compounds may be synthesized either from reactions between KF,HNF and RFOF [RF = CF3 or (CF3),CF] or CF2(OF)2,73a or by the addition of ONF to XCF=CF (X = F C1 or Br) using BF3 as a In the last type of reactions only one isomer (the anti-Markovnikov) is observed and they are rationalized in terms of the formation of CF3CFXBF2 intermediates which subsequently react with ONF,.The chemistry of CF2=NF (see 1981 and 1982 Reports) has been extended by the preparation of FS020CF2NFX (X = C1 Br or OS02F) from its reactions with XOS0,F. Reactions between CF,=NF and X (X = C1 or Br) in the presence of KF or CsF lead to CF3NXF via the CF3NF- anion and similar reactions involving RFCF=NF (RF = CF3 or C,F,) and Br have been performed in order to extend the range of fluorocarbon N-bromoflu~ramines.~~" Addition of CF3NBrF to several olefins has been dem~nstrated.~~' The reactions are highly regiospecific and the 67 A.I. Albanov L. I. Gubanova M. F. Larin V. A. Pestunovich and M. G. Voronkov J. Organomet. Chem 1983 244 5; Yu. L. Frolov T. N. Aksamentova G. A. Gavrilova N. N. Chipanina V. B. Modonov L. I. Gubanova V. M. D'yakov and M. G. Voronkov Dokl. Akad. Nauk SSSR 1982,267 646; Yu. L. Frolov M. G. Voronkov G. A. Gavrilova N. N. Chipanina L. 1. Gubanova and V. M. D'yakov J. Organomet. Chem. 1983 244 107. 68 (a)V.A. Pestunovich M. F. Larin A. I. Albanov L. I. Gubanova V. M. Kopylov and M. G. Voronkov Izu. Akad. Nauk SSSR Ser. Khim. 1983 1931; (b)A. K. Chelakov A. I. Prokofev N. N. Bubnov S. P. Solodovnikov A.A. Zhadanov and M. I. Kabachnik ibid. 1983,1037; A. K. Chekalov A. I. Prokofev N. N. Bubnov S. P. Solodovnikov and A. A. Zhdanov ibid. 1983 1184. 69 J. Mason and K. 0. Christe Inorg. Chem. 1983 22 1849. 70 A. M. Maurice R. L. Belford I. B. Goldberg and K. 0. Christe J. Am. Chem. SOC.,1983 105 3799. C. Chatgillaloglu and K. U. Ingold J. Phys. Chem. 1982 86 4372. 72 C. J. Eyermann W. L. Jolly S. F. Xiang J. M. Shreeve and S. A. Kinkead J. Fluorine Chem. 1983 23 389. 73 (a)W. Maya D. Pilipovich M. G. Warner R. D. Wilson and K. 0. Christe Inorg. Chem. 1983 22 810; (6) R.D. Wilson W. Maya D. Pilipovich and K. 0. Christe ibid. 1983 22 1355. 74 (a)S.-C. Chang and D. D. DesMarteau Inorg. Chem. 1983 22 805; (b)J. Org. Chem. 1983 48 895; (c) ihid.1983 48. 771. F Cl Br I At and Noble Gases products obtained are consistent with attack of CF3NF' at the least sterically hindered C atom. The CF3NF- anion generated in situ from KF and CF,=NF reacts with RC(0)F (R = F CF, C2F5 or CH,) to give CF,NFC(O)R and with CF2=NF to give CF,NFCF=NF If CsF is used to generate CF3NF- however the sole or major product is CF3NCF2NF resulting from a further reaction of F- with CF3NFCF=NF. This diaziridine undergoes an unusual isomerization in the presence of Fe Cr or Ni to give CF3N=NCF3.74C Mixtures of (CF3),N and SbF5 slowly eliminate CF when heated at elevated temperature and the presence of the heterocyclic cation (15) is indicated in the resulting solution by n.m.r. spectroscopy. The cation (1 5) is also obtained quantita- tively from the reaction of CF3NCF2 with SbF,.One of its hydrolysis products is (I 6) which has been characterized by X-ray ~rystallography.~~ The chemistry of halogen azides has been reviewed76 and reactions of CF3N3 with various halogen- containing oxidizers has been For example the compounds CF3NX(OSO2F) (X = F C1 Br or OSO2F)have been obtained from reactions with XOS02F and CF,NClF is formed by using C1F. 10 Halides of Phosphorus Arsenic and Antimony and their Derivatives New electron-diffraction investigations of the trigonal bipyramidal gaseous com- pounds PCl and SbCl have been made.78 In the case of PC& allowance was made for the thermal equilibrium PCl e PCl + C12.78a The bond distances obtained from the SbCl analysis are considerably closer to the values obtained from X-ray data than those determined previously.78b The primary products of the vapourization of AsCl,+AsF6- appear to be AsF and the previously unreported AsC1,F.The i.r. spectrum of the latter compound isolated in a low-temperature matrix is very similar to that of C,,,PC14F.79 Barriers to pseudo-rotational processes in a number of fluoro- and/or tri-fluoromethyl-substituted aminophosphoranes have been determined from ,'P and I3C n.m.r. line-shape analyses. values obtained are in the range 34.7 f 1.7 to 73.6 f4.2 kJ. Intramolecular hydrogen-bonding occurs between primary-amino H atoms and axial F atoms. At very low temperatures evidence for cessation of P-N rotation in F(CF,),PNMe2 was obtained the barrier being 31.4 kJ.80a The thermally 75 H.Burger R. Koplin G. Pawelke and C. Kriiger J. Fluorine Chem. 1983 22 175. 76 K. Dehnicke Adu. Inorg. Chem. Radiochem. 1983 26 169. 77 C. J. Schack and K. 0.Christe Inorg. Chem. 1983 22 22. 78 (n) B. W. McClelland L. Hedberg and K. Hedberg J. Mol. Strut. 1983,99 309; (b) L. S. Ivashkevich A. A. Ischenko V. P. Spiridonov T. G. Strand A. A. Ivanov and A. N. Nikolaev J. Struct. Chem. (Engl. Transl.) 1982 23 295. 79 F. Clam and R. Minkwitz 2. Anorg. Allg. Chem. 1983 501 19. 8o (a) R. G. Cavell S. Pirakitigoon and L. Vande Griend Inorg. Chem. 1983 22 1378; (b) L. Vande Griend and R. G. Cavell ibid. 1983 22 1817. 156 J. M. Winfield unstable CH3(CF3),PH has limiting 19F and 31P n.m.r.spectra which suggest that the ground-state geometry has two axial CF3- groups as part of a trigonal bipyramidal configuration about P.'" A number of monofluorophosphoranes are capable of existing in both molecular and ionic forms; an example reported this year is Ph,PF. The ionic form Ph,P+F- in which the cation is distorted by F- is prepared from Ph4P'Br- via anion exchange and the HF2- salt. Heating the F- or HF,-salts to ca. 573 K produces molecular Ph,PF which condenses to give a second ionic form [Ph,P][ trans-Ph4PF2].81 Ph3SbC12 forms 1 1 complexes with both SbCl and SbCI,. The former involves a weak interaction between the axial C1 atoms and adjacent Sb"' atoms producing a polymeric chain structure. The latter is ionic [Ph,SbCl][SbCi,] with residual cation...anion interaction C1...SbV = 3.23 1 .$ and the cation's geometry is inter- mediate between trigonal bipyramidal and square pyramidaL8 More examples of mixed-halogenophosphonium cations and -halogenophosphate anions have been reported most often as mixtures identified in solution by n.m.r.spectro~copy.~~ In some instances salts of discrete PF,-,Cl,- anions have been isolated,83h and evidence for fluxional behavicur obtained.83'.' The water soluble adduct PF5,NH3 can be prepared either from the direct reaction between PF and NH3 or from anhydrous HF and (F2PN),. It has a slightly distorted octahedral structure its thermal decomposition at 473 K yields PF,(NH,) and it reacts with additional NH to give PF3(NH2)2.84 Prrl-Pv bonded adducts are formed between RR'P(BlOHloC2)PR''"'' (R = R' = Ph or NMe,; R = R = NMe, R = R = NMe,; R' = R = F:R = R' = Ph; R = NMe,; R'" = F) and PF which undergo F- NMe exchange reactions on thermal decomposition.In MeCN the adduct Me2N(F)P(BloHloC2)P(F)NMe2,2PF exists in the ionic form [Me2NP(Bl,H,oC2)PNMe2][PF6]2 and its thermal decomposition leads to F,P(B loH,oC2)PF2.85 The fluxional behaviour previously noted for the six-co- ordinate phosphorus carbamate Me(CF,),P02CNMe2 has been shown to be due to exchange processes catalysed by fortuitous free amine. N.m.r. studies indicate that the CF groups are equivalent in solution at room temperature and that the low-temperature solution structure of the compound corresponds to that of the solid.' Gas-phase electron diffraction studies of X(PF,) (X = S or Se) show that both molecules have average structures with C2 symmetry but have large-amplitude torsional vibrations.The electron diffraction data for PF,(SMe) are consistent with three different conformations; that which is preferred is shown in Figure4.87 The shortest F...H distance 2.51 A is slightly less than the sum of the van der Waals radii. Reaction of S(PF,)2 with hydroxy-compounds is a good route to -0PF2 derivatives the general process being represented by M-OH + " S. J. Brown and J. H. Clark J. Chem. SOC.,Chem. Commun. 1983 1256. a2 M. Hall and D. B. Sowerby J. Chem. SOC.,Dalton Trans. 1983 1095. 83 (a)K. B. Dillon and A. W. G. Platt Polyhedron 1983 2 641; (b)J. Chem. SOC.,Dalton Trans.1983 1159; (c)J. Chem. SOC.,Chem. Commun. 1983 1089. a4 W. Stoner D. Schornburg G.-V. Roschenthaler and R. Schrnutzler Chem. Ber. 1983 116 367; W. Stoner and G.-V. Roschenthaler Chem.-Zrg. 1983 107 137. 85 C. B. Colburn W. E. Hill L. M. Silva-Trivino and R. D. Verma J. Fluorine Chem. 1983 23 261. 86 R. G. Cavell and L. Vande Griend Inorg. Chem. 1983 22 2066. 87 D. E. J. Arnold G. Gundersen D. W. H. Rankin and H. E. Robertson J. Chem. Soc. Dalton Trans. 1983 1989. F Cl Br I At and Noble Gases Figure 4 Perspective views of the conformation preferred for PF,(SMe) (a) perpendicular to the P-S bond and (6) along the P-S bond (Reproduced by permission from J. Chem. SOC.,Dalton Trans. 1983 1989) S(PF2) --* M-OPF + PF2HS.P"' and Pv derivatives for example P(OPF2)388a and PO(OPF,),,R,-,, n = 3 or 2; R = F or Ph n = 1;R = Ph,886 have been prepared by this means and have been characterized by spectroscopic methods. Further work on the reaction of (CF3)2PH with ZnMe has enabled an efficient synthesis of the ylide CF3P=CF2 to be devised. The key to the synthesis is the use of Me3N as a catalyst. CF3P=CF2 is stable with respect to oligomerization as a gas at 373 K or as a liquid at 195 K.89 11 Perfluoroalkyl and Alkyl Sulphur and Tellurium Halides Fluorination of CS with F2 at low temperatures and under carefully controlled conditions is a good synthesis for CF2(SF3)2.90 The reactions of this compound are analogous to those of SF,; it reacts with AsF giving SF3CF2SF3+AsF,- and with F2 or ClF in the presence of CsF giving F,C(SF,) or ~~~~s-(C~SF,)~CF,.The electron deformation density in Me2TeC1 has been determined from high-resolution X-ray intensity measurements at 151 K. TetV bonding and lone-pair densities in accordance with the predictions of a trigonal bipyramidal AB,E (E = lone pair) model are observed and the existence of intermolecular 'secondary' bonding is confirmed." Te(CF3) can be prepared from TeC1 and Hg(CF3) at high temperature in an inert atmosphere; by-products from the reaction are CF,TeCF,Cl and Te(CF2C1),. Low-temperature fluorination of TeMe does not produce fluorinated alkyl species ; the main product is Me2TeF2.92n Oxidation of Te(CF3)2 with CI, Br, 02,or C10N02 88 (a)E. A. V. Ebsworth G.M. Hunter and D. W. H. Rankin J. Chem. SOC.,Dalton Trans. 1983 1983; 89 (b) ibid. 1983 245. A. B. Burg Inorg. Chem. 1983 22 2573. 90 A. Waterfeld and R. Mews J. Fluorine Chem. 1983 23 325. 9' R. F. Ziolo and J. M. Troup J. Am. Chem. SOC.,1983 105,229. 92 (a)S. Herberg and D. Naumann Z. Anorg. Allg. Chem. 1982 492 95; (b) ibid. 1982 494 151 159. 158 J. M.Winfield leads to the TetV compounds (CF3),TeX (X = C1 Br or NO,; X 0. Other derivatives for example where X is F or OC(O)CF, are accessible by exchange reactions involving the halides X = C1 or Br.92b 12 Sulphur Selenium and Tellurium Oxofluorides and their Derivatives CF3S02F reacts with C2F4 in diglyme and in the presence of CsF at 363-373 K to give the sulphone CF3S02C2F5.The reaction is presumed to occur uia the generation of C2F5- in situ. More surprisingly (C2F5),S02 and (C2F5),S0 are formed from the analogous room temperature reaction between SOF and CZF4. This reaction is also believed to involve C2F5- but the mechanism of the reduction step is not clear. Probably the most general route to (R,),SO compounds is the hydrolysis of (RF),SF20 which can be prepared from the corresponding sulphides by a well established route.93 The well-known anion SO2F-,SOF3- which is believed to have C symmetry and SOzF3- which is analogous to the C,,molecule C102F3 have all been generated by reactions between CsF vapour and SO2 SOF, and S02F2 the ion pairs so produced being isolated in an Ar matrix and identified by i.r. spectros- copy.94" This is a widely used technique which is very successful when CsF is used.It is less useful when other alkali-metal fluorides or CsCl are used and possible reasons for this have been Chemistry associated with the ligands OXF (X = S Se or Te) has been reviewed:," and the compounds POF2(0TeF,) OP(OTeF,), P(OTeF,), As(OTeF,), and Sb(OTeF,) have been described.95b They are prepared using Hg(OTeF,), Xe(OTeF,), or C10TeF5. Both cis-and trans-HOTeF,(OMe) react with BCl to give the analogous B[OTeF,(OMe)] compounds and these in turn can be used to prepare other derivatives for example AS[OT~F,(OM~)]~.~~~ Pyrolysis of (CF,),CS(O)C(CF,),S(O) at 723 K has led to the first example of a perfluoroalkyl sulphine (CF3),C=S=0. Its I9F n.m.r. spectrum indicates that the CF3-groups are n~n-equivalent.~~ 13 Sulphur-Nitrogen and Tellurium-Nitrogen Halides and Their Fluorocarbon Derivatives The first thiadiaziridine C2F5N-S-NC2F5 has been prepared albeit in small yield by the photolysis of C2F5N=NC2F5 with SC1 at 273 K.97 S4N4 and CIF undergo a complex series of reactions giving initially NSCl (NSCI), and NSF.NSCl reacts further to give NSF then CINSF,; the final reaction products are N, Cl, and SF,. The reaction of NSCl with ClF to give NSF and C1 can be driven in the reverse direction by adding SO2 as ClF is then removed from the system as S0,ClF. NSF is conveniently synthesized by passing NSCl through a CsF column at 383 K.98CF3SC1 reacts with Me3SiN to give (CF,SN),. This can be kept at 243 K for a few days but it oligomerizes at room temperature.CF,S(F)N=C(O)F 93 T. Imagawa G. L. Card T. W. Mix and J. M. Shreeve Inorg. Chem. 1983 22 969. 94 (a)K. Garber and B. S. Ault Inorg. Chem. 1983 22 2509; (b)B. S. Ault ibid. 1983 22 2221. 95 (a)K. Seppelt Angew. Chem. Int. Ed. EngL 1982 21 877; (b)D. Lentz and K. Seppelt Z. Anorg. Allg. Chem. 1983 502 83; (c) W. Totsch H. Aichinger and F. Sladky Z. Naturforsch. Ted B. 1983 38 332. 96 A. Elsaper and W. Sundermeyer Tetrahedron Lett. 1983 24 2141. 97 R. C. Kumar and J. M. Shreeve J. Chem. Soc. Chem. Commun. 1983 658. 98 A. J. Banister R. G. Hey J. Passmore and M. N. Sudheendra Rao J. Fluorine Chem. 1982 21 429. 159 F Cl Br I At and Noble Gases which is prepared from CF3SNC0 and F2 at 195 K reacts with HgF2 at room temperature to give (CF3SN),.99 The Lewis acid-base properties of NSF are retained when it is co-ordinated to a transition metal.Thus (OC),Re(NSF)' reacts with Me3SiNMe2 with the elimination of Me3SiF to give [(OC),Re(NSNMe,)]+ and with (Me,Si),NMe in a similar fashion giving [(OC),Re{NSN(Me)SN)Re(CO)5]2+. The ReNSN moiety in the former cation is bent.'"" (OC),Re(NSF)+ reacts with AsF to give (OC)5Re(NS)2' and AsF,-.'OOb The formation of NSON(CF3)2 from NSF and (CF,),NO was reported some time ago and the compound has now been shown to behave as a ligand towards several transition metals in +1 and +2 oxidation states.'" Oxidation of S2N+ by Cl or Br in SO leads to (SX)2N+ X = Cl or Br isolated as their AsF,- salts. An analogous reaction using XeF as oxidant and S02F2as solvent yields (F2S),N+AsF,-.The cation's symmetry is essentially C," Figure 5 Figure 5 7le (SF,),Nf cation with anion contacts (Reproduced from J. Chem. Soc. Dalton Trans. 1983 1961) and the S-N bond distances suggest a bond-order of 1.85.*02 The structure of F2SNC(0)F in the gas phase has been determined from its microwave spectrum. A single conformer is present in which N and S lone-pairs occupy cis positions (17) and the S-N bond distance 1.405A is considerably shorter than that expected for a double bond.Io3 Fe,f=N\ ,F F o4 (17) The compounds RFN=SF2 (RF = CF3 C2F5 or i-C3F7) can be methylated in SO2 to give R,(Me)NSF,+ salts and from these a variety of RdMe)N-containing com- pounds have been prepared for example R,(Me)NS(O)F RF(Me)NSF3 and CF3(Me)NSC1.104 The low temperature 1 12 K crystal structure of P~,As+N(SO~F)~- indicates that the anion has a staggered conformation of approximate C2symmetry Figure 6a.The apparently different geometry observed at 290 K Figure6b is YY D. Bielefeldt and A. Haas Chem. Ber. 1983 116 1257. 100 (a) G. Hartmann R.Mews and G. M. Sheldrick Angew. Chern. Int. Ed. Engl. 1983,22,723 Supplement p. 945; (b)R. Mews and C. Liu ibid. 1983 22 162. G. Hartmann R. Mews and G. M. Sheldrick J. Organomet. Chem. 1983 252 195. 101 I02 W. V. F. Brooks G. K. MacLean J. Passmore P.S. White and C.-M. Wong J. Chem. SOC.,Dalton Trans. 1983 1961.. I03 S. R. Bailey and J. D. Graybeal J. Mol. Spectrosc.1982 92 117. I04 H. Henle and R. Mews Chem. Ber. 1982 115 3547. J. M. Winjield Figure 6 The N(SO,F),-anion (a) af 112 K (6) at 290 K (Reproduced by permission from Acra Crystallogr. 1982 B38 2887) accounted for on the basis of two superimposed conformers which are subject to considerable thermal smearing. Low-temperature crystallography is therefore crucial in obtaining a chemically sensible structure for this compound.105 Imidodifiuorosul- phates of divalent transition-metals M(NSOF2)2 (M = Co Ni or Cu) can be obtained from [M(S02)2][AsF6]2 and R3SiNSOF2 in SO2.In two cases the reaction intermediates Cu(NSOF2)(AsF5NSOF2) and N~(SO,),[ASF,(NSOF~),]~ have been isolated and the latter's structure is shown in Figure 7.*06Hg[N(SF,)2]2 is a useful Figure 7 Molecular strucrure of Ni(S02)2[AsF,(NSOF2)2]2 (Reproduced by permission from Chem.Ber. 1983 116 874) I05 W. Isenberg M. Noltemeyer and G. M. Sheldrick Acta Crystallogr. 1982 €338 2887. I06 R. Hoppenheit R. Mews M. Noltemeyer and G. M. Sheldrick Chem. Ber. 1983 116 874. F CZ Br I At and Noble Gases 161 reagent for the introduction of -(SF,) groups. It reacts with Me1 and CF,SCl to give MeN(SF,) and CF3SN(SF5) respe~tively.'~' Compared with the large number of TeF,O- compounds which are known (see Section 12) few examples of TeF,N= compounds have been reported. However feasible routes to such compounds are beginning to emerge for example H2NTeF or Me3SiN(H)TeF are suitable starting materials for the preparation of compounds such as OCNTeF, Cl,W=NTeF, and Cl,Se=NTeF,.The X-ray crystal structure of Cl,W=NTeF shows that the W-N-Te linkage is almost linear (171") and that WCl and TeF moieties are eclipsed. It is concluded that there is some double bond character throughout the system.'Oga Irradiation of TeF,Cl and RCN (R = C1 or CF3) at room temperature gives F,TeN=CRCl. From F,TeN=CCl other deriva- tives for example F,TeN=CF, F,TeNCF3- and CF3N(TeF,), are accessible. The latter compound provides the first example of a Te-N-Te linkage.'086 14 Structural Work on Solid Hexafluorides Neutron diffraction studies have been made on polycrystalline MoF, WF6 and UF6 at 77 K completing a structural investigation of solid MF6 (M = S Mo W or U) phases. The existence of the orthorhombic &ma phase for the metal hexafluorides down to 77 K is confirmed.M-F bond lengths do not decrease significantly on cooling to 77 K but the octahedra pack more efficiently and make a closer approach to the ideal hexagonal close-packing of F atoms. MoF, WF, and especially SF are more compact and spherically-shaped molecules than UF, explaining the absence of a plastic phase in the latter and the larger temperature range over which plasticity is observed in SF6.109 The MF (M = Mo W or U) molecules in the solids show no deviation from Oh symmetry within the level of accuracy of the data. I9F N.m.r. spectra of polycrystalline UF have been cited as evidence for distortion in the molecules however in the latest interpretation it is concluded that they have Oh symmetry.' lo Molecular dynamics calculations have reached the stage where they are able to reproduce all the solid-state phase transitions in SF6 and they have been used to make suggestions about the nature of the disorder in the plastic phase." Micro-crystals of MF6 (M = S Se or Te) have been produced in nozzle flows of these gases mixed with noble gases.Their examination by electron diffraction shows that orthorhombic Pnma or cubic plastic phases are produced depending on the MF6 partial pressure and the nucleation conditions used. The low-temperature phases produced in this study differ from their metal hexafluoride counterparts in being less dense than the cubic forms."2 A detailed analysis of site symmetry effects in the i.r. spectra of SF6 or SeF isolated in noble gas solids has been made.'I3 Ordered orientation of SF in Kr is particularly pronounced but it is observed in all the systems examined (see also re$ 19c).I07 A. Waterfeld and R. Mews Chem. Ber. 1983 116 1674. 108 ((1) H. Hartl P. Huppmann D. Lentz and K. Seppelt Inorg. Chem. 1983 22 2183; (b) J. S. Thrasher and K. Seppelt Angew. Chem. Int. Ed. Engl. 1983 22 789 Supplement p. 1106. I09 J. H. Levy J. C. Taylor and A. B. Waugh J. Nuorine Chem. 1983 23 29. I10 E. P. Zeer 0.V. Falaleev and V. E. Zobov Chem. Phys. Lett. 1983 100 24. Ill G. S. Pawley and M. T. Dove Chem. Php. Lett. 1983 99 45. I12 E. J. Valente and L. S. Bartell J. Chem. Phys. 1983 79 2683. 113 L. H.Jones and B. I. Swanson 1. Chem.Phys. 1983 79 1516. 162 J. M. Winfield 15 Binary Halides of &Block Elements What may be a new hexafluoride PdF, has been reported to be the product from the reaction between Pd metal and F, passed through a high-voltage electrical discharge at 330 K. The thermally unstable solid is a strong oxidizing agent.Il4 Halogen exchange reactions of OsF, w6 and RuF result in reduction of the metal and in some cases the formation of polymeric mixed halides for example Ir2F3C16 Os,Br4F, and Ir2Br4F5.' Electronic and vibronic energy levels derived from the 12i configuration in OsF have been studied by electronic Raman scattering and absorption spectra from OsF doped in single crystal MoF or WF hosts. The first excited state TZFlies very close to the Egground state and Jahn Teller effects are observed in the TI excited state.I16 Electron diffraction studies of gaseous MoCl and WCl do not distinguish between D3, and C, structures and its seems therefore that the barrier between them is small."' By the same technique the presence of D,, (NbF,)3 has been detected in NbF vapour at 333 K."' An analogous species has been observed in TaF previously.Molten MoF appears from a study of its magnetic susceptibility to contain (MoF,), n = 3,4 or 5 chains in which the Mo" centres are antiferromagnetically coupled.' l9 A new modification of NbBr has been inadvertantly prepared by the reaction of NbBr with sulphur in a closed tube. It is isostructural with TaI, layers of (NbBr,) being stacked with displacement faults along the b direction.I2' Although several ternary fluorides containing Ag"' are known the binary fluoride had not been isolated until this year.AgF3 has been prepared as a reddish-brown paramagnetic solid from the oxidation of AgF by KrF in anhydrous HF.'" FeF3(H20)o,33,grown by hydrothermal synthesis has a Fe"'F framework related to that of the hexagonal W bronze Rbo.29W03. H20 is evolved on heating to 395 K without any noticeable change in the F skeleton so the resulting anhydrous FeF is a new modification. It transforms to the cubic-ReO type at 798 K.I2,= Red monoclinic Fe3F,,2H,0 which is also obtained by hydrothermal synthesis contains layers of [Fe"'F,,,] octahedra connected by corner-sharing to [Fe"F4,2(H,0)2].'22h a-RuC13 has a layer-type AlCl structure and various guest molecules have been intercalated using electrochemical or chemical techniques.RuBr shows similar behaviour. 23 Binary chlorides of Fe Co and Ni have been obtained in Ar-matrices from sputtering reactions of the metals in isotopxy enriched CI,-Ar atmospheres. 1.r. spectroscopy of the species indicate that ClMCl (M = Fe or Co) are greater than 120" in MCl3 as expected for planar molecules whose vibrations are somewhat I14 A. A. Timakov V. N. Prusakov and Yu. V. Drobyshevskii Russ. J. Inorg. Chem. (Engl. Transl.) 1982 27 1704. I I5 R.C. Burns and T. A. O'Donnell J. Fluorine Chem. 1983 23 1. I16 D. L. Michalopoulos and E. R. Bernstein Mol. fhys. 1982 47 I. I I7 Yu. S. Ezhov and A. P. Sarvin J. Strct. Chem. (Engl.Trans/.) 1983 24 49 140. I18 G. V. Girichev V. N. Petrova V. M. Petrov and K. S. Krasnov Koord. Khim. 1983 9 799. I19 V. N. Ikorskii and K. A. Khaldoyanidi J. Struct. Chem. (Engl. Trans[.) 1982 23 302. I2O U. Muller and P. Klingelhofer Z. Naturforsch. Teil E 1983 38,559. I21 R. Bougon and M. Lance C.R. Hebd. Seances Acad. Sci. Ser. II 1983 297 117. I22 (a) M. Leblanc G. Ferey P. Chevallier Y. Calage and R. De Pape J. Solid State Chem. 1983,47 53; (b) E. Herdtweck Z. Anorg. Allg. Chem. 1983 501 131. R. Schollhorn R. Steffen and K. Wagner Angew. Chern.. Int. Ed. Engl. 1983 22 555. F Cl Br I At and Noble Gases 163 anharmonic. The dihalides MC1 (M = Fe Co or Ni) are believed to be non-linear in contrast to some previous work.'24 Treatment of Pd3(02CMe)6 in glacial acetic acid with either HCl or CO and HC104 produces P-PdCl, Pd6ClI2 quantitatively. These are the first useful syntheses of this form.'25 A re-investigation of VCl2,2thf by X-ray crystallography has shown that the compound is actually [(thf)3VC13V(thf)3]2[C12ZnC12ZnC12], the bource of the anion being Zn metal which is used to perform the VC13 -* VC12 reduction.'26 16 Halogenometallates of the &Block Standard enthalpies of formation of solid K3MF6 (M = Sc-Cu inclusive and Ga) have been determined by solution calorimetry. The derived values of AH; from the constituent gaseous ions Kf M3+ and F- show the familiar double-humped curve when plotted against the number of M3+ 3d electrons as predicted by ligand-field theory.However the magnitudes of the humps are somewhat larger than e~pected.',~ The redox couples MF6'"-' (M = Ta W Re Os Nb Mo or Ru; z = 0 -1 or -2) have been detected in MeCN by cyclic voltammetry.'28 Analogous couples originating from 4d and 5d elements are almost uniformly separated by 1.O V the former being the more oxidizing and linear progressions in the observed E" values occur for electronic configurations up to and including d3. MoC~,~-has been identified in a basic AlCl, N-n-butylpyridinium chloride melt and its reversible reduction to MoClB- dem0n~trated.I~~ The ion was generated by dissolution of MoCI or MoC16- in the melt and the apparent instability of MoV contrasts with previous studies of MoV in basic AlCl,,NaCl melts.(Et,N)OsC16 is formed quantitatively by heating the corresponding salts of tr~ns-[OsX,(CO)~]- (X = Br or I) in C12 at 393 K. The OsC16- anion is readily reduced to osc162-.'30 Although the cell dimensions of Pb2RhF7 are similar to those of K2NbF7 its structure is different being Pb,F[RhF,] in which the RhF6 group is a distorted ~ctahedron.'~' The TaF,2- ion in solid K2TaF is fluxional and its vibrational spectrum cannot be assigned on the basis of any of the polyhedra commonly used for seven-co-ordinate compounds. At lower temperatures it adopts a rigid structure of low symmetry and the anions are stationary on the n.m.r. time scale below 150 K.l3 The trirutile LiV2F6 is a true mixed-valence compound which contains pairs of crystallographically equivalent orthorhombically distorted VF6 octahedra that share one edge.Its tem- perature-dependent magnetic susceptibility has been interpreted on this Defect structures in the hexagonal vanadium bronzes A,VF3 (A = K Rb Cs or TI; 0.18 S x G 0.32) have been observed by electron I24 D. W. Green D. P. McDermott and A. Bergman J. Mol. Spectrosc. 1983 98 11 1. I25 A. Yatsimirski and R. Ugo Inorg. Chem. 1983 22 1395. I26 F. A. Cotton S. A. Duraj M. W. Extine G. E. Lewis W. J. Roth C. D. Schmulbach and W. Schwotzer J. Chem. SOC. Chem. Commun. 1983 1377. 127 P. G. Nelson and R. V. Pearse J. Chem. SOC.,Dalton Trans. 1983 1977. 128 S. Brownstein G. A. Heath A. Sengupta and D. W. A. Sharp J. Chern. SOC.,Chem. Commun. 1983,669. 129 T. B. Schemer C. L.Hussey K. R. Seddon C. M. Kear and P. D. Armitage Inorg. Chem. 1983,22,2099. 130 W. Preetz and M. Bruns Z. Naturforsch. Ted B 1983 38 680. 131 R. Domesle and R. Hoppe Z. Anorg. Aflg. Chem. 1983 501 102. I32 R. B. English A. M. Heyns and E. C. Reynhardt 1. Phys. C. 1983 16 829. '33 (a)R. M. Metzger N. E. Heimer C. S. Kuo R. F. Williamson and W. 0. J. Boo Inorg. Chem. 1983 22 1060; (b)D. Rieck R. Langley and L. Eyring J. Solid State Chem. 1983 48. 100. I64 J. M. Winjield New fluoropalladates( 11) reported this year include orange-brown CsPd2FS in which Pd" has both octahedral and planar environments.'34a Evidence for Pd"' in NaPdF comes from an e.p.r. study. The compound's structure is derived from the KBrF type but the low spin Pd"' environment is axially A compound which has a related structure is CsCuF,.It contains the first example of diamagnetic Cu"' in a square planar en~ir0nment.I~~' Although CuF has not been isolated Cu' is stable as a dilute solid solution in NaF due to the favourable heat of solution of Cu' as compared to Cu2+ and Cu and to a favourable entropy of mixing. One- and two-photon polarized spectroscopic studies of the 3d lo--* 3d94s transition have been made and a Jahn-Teller effect ~bserved.'~' The low temperature S443 K crystal modification of CsAgCl contains cubically co-ordinated Cs' and trigonal- bipyramidally co-ordinated Ag+. The compound reacts with C12 to give black CsAgCI,, (x = ca. 0.125) with essentially the same str~cture.'~~ The reaction between AgF and UF in anhydrous HF yields an insoluble solid analysing as Ag,UF8.However the solid has unexpected oxidizing ability and it could be a mixture containing AgF and Ag1UVF6.'37 17 Oxohalides Chalcogen-halides and Oxohalogenometallates of d Block Elements The structure of CrO,F in the gas phase has been re-investigated by electron diffraction and its quadratic force-field determined.I3* The structural parameters obtained are in a harmony with those reported last year for Cr02C12. Cooling VOC13 below its m.p. 196 K produces a yellow amorphous phase which transforms to an orange orthorhombic phase on further cooling. Low temperature X-ray crystallogra- phy and 35Cl n.q.r. spectroscopy show that the orthorhombic phase comprises VOC13 molecules C symmetry stacked to form trigonal prismatic columns Figure 8.Intramolecular bond distances and angles are very similar to those determined for the gas phase and the overall structure of the solid is more closely related to those of POC13 and Main-Group V trihalides (see 1982 Report) than to other transition- metal oxotrihalides. 139 The i.r. and electronic spectra of matrix isolated WSX, and WSeX (X = F C1 or Br) have been observed and assignments made on the basis of C, The crystal structures of MSF (M = W or Re) which are prepared in high yield from reactions of MF6 with sulphur at 573 K contain cis-F bridged polymers. The adduct WSF,,NCMe is monomeric.'40b Treatment of NbSX3 (X = C1 or Br) with tetrahydrothiophene (tht) gives NbSX3,2tht as the initial products but complex redox-disproportionations occur subsequently yielding [(tht),XzNb(pS2)(p-I34 (a)B.G. Muller Z. Anorg. Allg. Chem. 1982 491 245; (b)A.Tressaud S. Khairoun J.-M. Dance J. Grannec G. Demazeau and P. Hagenmuller C. R. Hebd. Seances Acad. Sci Ser. ZZ 1982 295 183; (c)T. Fleischer and R. Hoppe 2. Anorg. Allg. Chem. 1982 492 76. S. A. Payne A. B. Goldberg and D. S. McClure 1. Chem. Phys. 1983 78 3688. I36 H.-C. Gaebell G. Meyer and R. Hoppe Z. Anorg. Allg. Chem. 1983 497 199. 13' J. G. Malm J. Fluorine Chem. 1983 23 267. I38 R. J. French L. Hedberg K. Hedberg G. L. Gard and B. M. Johnson Inorg. Chem. 1983 22 892. I39 J. Galy R. Enjalbert G. Jugie and J. Strahle J. Solid Stare Chem. 1983 47 143. I40 (a)P. J. Jones W. Levason .I.S.Ogden J. W. Turff E. M. Page and D. A. Rice J. Chem. SOC.,Dalton Trans. 1983 2625; (b)J. H. Holloway V. KauEiE and D. R. Russell J. Chem. SOC.,Chem. Commun. 1983 1079. F Cl Br I At and Noble Gases 165 Figure 8 Perspective view close to the (001) ptane of the molecular packing in VOCI (Reproduced by permission from J. Solid Stare Chem. 1983 47 143) S)NbX,(tht),]. In the adduct Nb=S is trans to one tht ligand and the Nb'V...NblV distances in the final dinuclear products indicate a single metal-metal intera~ti0n.I~' Recent investigations of oxofluorometallates have a structural bias X-ray crystal- lography being the most popular technique supplemented when disorder exists by vibrational spectroscopy. Anions that have been examined in this way include those of~V142a vIV 142b Vv or VIV doped into MoV1oxofluorometallates,142"and WV1.142c Cs3[V204F5] in which the Vv atoms are statistically disordered over all (0,F) octahedral exhibits a weak red emission at low temperature^.'^^ y-Irradi-ation of (NH4)3V02F4 results in an e.p.r.spectrum which is assigned to the trans-(V02F4)4- anion,I4" and the corresponding Vv anion has been identified by "V and '9Fn.m.r. spectroscopy in acidified aqueous solutions of Na( NH4)2V02F4.'44b V205 in 48% aqueous HF has an identical spectrum although the species formed in this solution was previously believed to be VOF,-. Solid products obtained from the thermal decomposition of (NH4)3W02F5are believed to be oxofluoride tungsten bronzes in which NH4+ H2F+ and H30+ cations occupy interstitial positions.145 Numerous compounds of the type A2MOX (A = K Rb or Cs; M = Cr Mo W Tc or Re; X = C1 or Br) have been claimed in the literature but a careful preparative study indicates that not all can be isolated in a pure state.Solubilities redox stabilities and tendencies to undergo disproportionation are all im~0rtant.I~~ The reaction between NbCI5,NbOCI3 and PhCrCPh in CH2C12 leads to dark green [Ph4C4C1][Nb20CI,]. The Nb-0-Nb linkage in the anion is almost linear 174" and two anions are linked by asymmetric C1-bridges to give a centro-symmetric dimer [C1sNbONbC13C12,2]22-.147 141 M. G. B. Drew D. A. Rice and D. M. Williams J. Chem. SOC.,Dalton Trans. 1983 2251. I42 (a)R. Mattes and H. Forster J. Less-Common Met.1982 87 237; (b)J. Solid Stare Chern. 1982 45 154; J. Mazicek V. K. Tranov and L. A. Aslanov Koord. Khirn. 1982 8 1550; (c) R. Dornesle and R. Hoppe 2. Anorg. Allg. Chem. 1982 492 63; W. Massa S. Hermann and K. Dehnicke ibid. 1982,493 33; R. Mattes and H. Forster ibid. 1982 494 109. 143 G. Blasse and G. J. Dirksen 2. Natttrforsch. Teil B 1983 38 788. 144 (a) U. R. K. Rao K. S. Venkateswarlu B. R. Wani M. D. Sastry A. G. I. Dalvi and B. D. Joshi Mol. Phys. 1982 47 637; (b)R. J. Gillespie and U R. K. Rao J. Chem. Soc. Chem Commun. 1983 422. I45 E. G. Rakov E. I. Mel'nichenko and S. A. Polishchuk Russ. J. Znorg. Chem. (Engl. Trans/.) 1983 28 138. 146 J. E. Fergusson A. M. Greenaway and B. R. Penfold Inorg. Chim. Acta 1983 71 29. 147 E.Hey F. Weller and K. Dehnicke 2. Anorg. Alfg. Chem. 1983 502 45. J. M. Winfield 18 Actinide Halides The electron affinity of UF6 has been determined to be 5.50 * 0.3 eV by an effusion mass spectrometry method this value being in good agreement with a previous I.C.R. determinati~n.'~~ From a re-investigation of its valence electron spectrum it has been suggested that the HOMO of UF has t, symmetry a similar situation to that in SF, MoF, and WF, rather than t, as has been generally assumed.'49 Photodissociation of PuF at 337 nm appears to yield PuF5 but its existence under these conditions is only transitory and further dissociation occurs giving PuF4.1So UF5 has a much longer lifetime under similar conditions (See 1981 Report). Reduc- tion of UF6 by PF is a convenient synthetic route to P-UF5,15' and good evidence for the series of mixed halides UF,-,CI (n = 1-5) has come from a low tem- perature i.r.study of reactions between UF and BC13 or TiCl in liquid Xe.19' Bands attributable to all members except trans-UF4C12 were observed. A detailed thermochemical study of the reactions 2AX(c) + ThX,(c) = A2ThX,(c) (A = K or Cs; X = C1 or Br) has been carried out and enthalpies of formation of MX,2-(g) (M = Th or U) and the two-halide ion affinities of MX4 cal~ulated.'~~ A number of structural investigations of lower oxidation-state halides and their com- plexes have appeared.'53 Np,F 2rH20has a three-dimensional network structure in which NpF (tricapped trigonal prism with two corners missing) and NpFs (bicapped trigonal prism and antiprism) polyhedra can be distinguished.H20 molecules are located in lattice 'holes' at 2.54 and 2.43 8 from Np; Np-F are 2.18-2.78 A.153a NaNp,F ,is structurally related to CsU,F2 and contains NpF tricapped trigonal prisms in which Np-F are 2.288-2.55 A."" Solid AmI has two phases the transition point being 673 * 30 K. The low temperature orthorhombic phase is of the PuBr type; the high temperature hexagonal phase has the BiI structure. They can be distinguished from their electronic absorption spectra and are prepared from 243Am with I2 at 573 K and from 243Am02 with HI above 873 K respectively. Reaction of 243Am13 with moist HI above 823 K leads to 243AmOI which has the PbClF K2UC15 has a chain structure based on monocapped trigonal prisms linked via two common edges [UC13C12/2C12/2].153d A consideration of lattice constants and molar volumes suggests a close relationship between U'"-Cl com-pounds and their Ce"' analogues,'53d and a similar conclusion has been drawn from a study of CeCl complexes compared with their U'" counterpart^.'^^ Anodic oxidation of Th metal into a solution of I2 in MeCN allows the isolation of Th12,2MeCN from which ThI [alternatively formulated as Th4+(e),I,] is easily obtained.The method is more convenient than the alternative high-temperature synthesis.155 I48 A. T. Pyatenko A. V. Gusarov and L. N. Gorokhov Russ. J. Phys. Chem. (Engf. Transl.) 1982,56 1164. I49 N. Mirtensson P.-A. Malmquist and S. Svensson Chem. Phys.Len. 1983 100 375. Iso K. C. Kim and G. Campbell Chem. Phys. Len. 1983 98 491. 151 T. A. O'Donnell R. Rietz and S. Yeh J. Fluorine Chem. 1983 23 97. IS2 A. D. Westland and M. T. H. Tarafder Can. 1. Chem. 1983 61 1573. IS3 (a)A. Cousson H. Abazli M. Pages and M. Gasperin Actn Crysrallogr. 1983 C39,425; (b)ibid. 1983 C39 318; (c)R. G. Haire J. P. Young and J. R. Peterson 1.Less-Common Mer. 1983 93 339; (d)G. Meyer H.-Chr. Gaebell and R. Hoppe ibid. 1983 93 347. I54 J. Barry J. G. H. du Preeze T. I. Gerber A. Litthauer H. E. Rohwer and B. J. van Brecht J. Chem. SOC.,Dalton Trans. 1983 1265. 155 N. Kumar and D. G. Tuck Inorg. Chem. 1983 22 1951. F Cl Br I At and Noble Gases 167 19 Lanthanide Halides He' PE spectra of several gaseous LnX (Ln = La Ce Nd Er or Lu; X = C1 Br or I) have been reported together with Xa calculations and comparisons with previous related work on the fluorides.Early members of the lanthanide series have 4f-like ionizations at lower energies than the ligand p-like orbitals but this situation is reversed for later members. Fluorides show predominantly ionic bonding covalent character increasing with increasing mass of the halogen. 156 The X-ray crystal structure of [N(C6H,CH3)Et3]2[CeC16] shows a distorte%tahe- dral CeC1,2-anion in which Ce-Cl = 2.594-2.619 A and ClCeCl = 88.25-90.50°.'57" Although CeC162- decomposes readily at ambient temperature in many solvents it appears to be stable indefinately in SOC12.1s4 Photoreduction occurs in MeCN at all wavelengths corresponding to the charge-transfer bands of CeC162-.The process involves loss of C1' after direct transfer of an electron from ligand to Decomposition of CeC1,2- salts having Nk' and related cations occurs at moderate temperatures but C12 is not always observed as a product.'s7' The electron affinity of CeF, determined by an effusion mass spectrometric method is as expected relatively large 3.6 f 0.3 eV."* The compounds A,LnF7 (A = Group 1 cation; Ln = Ce Pr or Tb) have the (NH3)3ZrF7 structure. These and other Ln'" complex fluorides of the A,LnF or A'LnF (A' = Group I1 cation) types can be prepared by high temperature fluorination^.'^^ Reactions involving Xe fluorides or KrFz are an alternative synthesis.2' Reduction of LnF by Cs or Rb metals has resulted in the isolation of the cubic perovskites CeEuF (yellow) CsYbF (bright green) and RbYbF (orange).',' Reduction of GdI by Gd metal and graphite at 1170 K produces GdI2C6II7.This compound contains Gd6II2 clusters linked via trans edges of the Gd6 octahedra to give linear trimeric units which are further linked via cis edges forming zigzag chains. C2 units are located at the centres of the Gd octahedra.'6' A well-resolved i.r. spectrum of matrix-isolated YbC12 has been obtained and from this the 6Cl angle has been estimated to be 126 f5°.162 20 Graphite-Halide Intercalation Compounds and Graphite Fluorides Intercalation of halogens and halides continues to be widely studied. Recent results and references to the earlier review literature are contained in two reviews dealing with graphite intercalation corn pound^.'^^ One of the most interesting developments this year is the demonstration of F2 intercalation which has been reported by two '56 B.RuSEiC G. L. Goodman and J. Berkowitz J. Chem. Phys. 1983 78 5443. 157 (a) V. M. Agre and Yu.M. Kiselev Russ.J. Inorg. Chem. (Engl. Transl.) 1983,28,334; (b)L. L. Costanzo S. Pistara and G. Condorelli J. Photochem. 1983 21 45 (c)Yu. M. Kiselev and A. I. Popov Russ. J. Inorg. Chem. 1983 28 190. Is* E. B. Badtiev N. S. Chilingarov M. V. Korobov L. N. Sidorov and I. D. Sorokin High Temp. Sci. 1982 15 93. I59 K. Feldner and R. Hoppe Rev. Chim. Minirale 1983 20 351. 16V G.-Q. Wu and R. Hoppe Z. Anorg. Allg. Chem. 1983 504 55.161 A. Simon and E. Warkentin 2. Anorg. Allg. Chem. 1983 497 79. I62 1. R. Beattie J. S. Ogden and R. S. Wyatt J. Chem. Soc. Dalton Trans. 1983 2343. I63 N. Bartlett and B. W. McQuillan in 'Intercalation Chemistry' ed. M. S. Whittingham and A. J. Jacobson Academic Press New York and London 1982 Chapter 2 p. 19; W. C. Forsman and T. Dziemianowic Synthetic Metals 1983 5 77. 168 J. M. Winjield groups.'64 In one case the reaction occurs ca. 293 K in the presence of anhydrous HF to yield first stage C,F (5 > x > 2) via the second stage compound C12+HF2-.164n In the other study C,F (x > 2) were prepared by exposing HOPG to F2 gas with catalytic quantities of AsF, IF5 or OSF,.'~~' In both cases the products are distinct from the known covalent graphite fluorides (see below) and in one very highly conducting materials were obtained.The identity of the intercalated species has not yet been established. Semi-ionic C-F bonding has been postulated,'64* and mobile F2 is another po~sibility.'~~' Intercalation of Br in graphite was first demonstrated many years ago but the identity of the resulting intercalated species is still not established with certainty. In one of several recent X-ray structural studies the presence of interacting Br4"- units having interatomic distances comparable to those in known polybromide anions has been po~tulated.'~~ Intercalation of S206F2 into various types of graphites has been reinvestigated. A rearrangement occurs shortly after intercalation presumably to give S03F-.The maximum degree of intercalation achieved corresponds to C7S03F and electrical conductivity reaches a maximum ca. C I 2-16S03F.166a C8S03F undergoes irreversible solvolysis in CF,S03H to give C12S03CF3 whose spectra support an ionic formula- tion,'666 and in liquid SbF5 to give C8+SbF6- in quantitative yield.166c Both reactions have counterparts in conventional inorganic chemistry. Intercalation of SbC15 in graphite leads to compounds in which both Sb" and Sb"' are present. In a model deduced for the intercalate layer from an X-ray diffraction Sb" atoms are located on a mirror plane at the layer's centre and are flanked by Sb'" layers with C1 layers contacting the boundary C layers. Raman spectroscopy is useful for investigating these compounds and the use of this technique applied to a dilute first stage SbC15 intercalate suggests that species formally related to SbCl, SbCl,,- SbC163- and SbC16- are present.'67b Raman spectroscopy can also be usefully applied to monitor the course of the intercalation process.16" Although SbC15 intercalated graphites are often regarded as being air-stable (e.g. ref 167a) changes do occur in the first stage compound on exposure to air for example de-intercalation with subsequent hydrolysis and the formation of higher- staged compounds.167b Similar phenomena have been documented for FeC1,- graphites indicating that for these materials also the assumption of air stability is unjustified. FeC1,-intercalates obtained by H2 reduction of Fe"' precursors are even more air sensitive.'68a The covalent graphite fluoride (C,F) is now recognized as a chemical entity which is distinct from covalent (CF), and it can be formed by the reaction of Fz I64 (a)T.Mallouk and N. Bartlett J. Chem. Soc. Chem. Commun. 1983 103; (b)1. Palchan D. Davidov and H. Selig ibid 1983 657. 165 D. Ghosh and D. D. L. Chung Muter. Res. Bull. 1983 18 1179. 166 (a)J. G. Hooley Carbon 1983 21 181; (b)S. Karunanithy and F. Aubke ibid. 1982 20 237; (c)J. Nuorine Chem. 1983 23 541. 167 (a)M. H. Boca M. L. Saylors D. S. Smith and P. C. Eklund Synthetic Metals 1983 6 39; (b)W. Jones P. Korgul R. Schlogl and J. M. Thomas J. Chem. SOC.,Chem. Commun. 1983,468; J. M. Thomas R. Schlogl W. Jones and P. Korgul Carbon 1983 21 409; (c) R.Schlogl W. Jones and J. M. Thomas J. Chem. SOC.,Chem. Commun. 1983 1330. I68 (a)R. Schlogl P. Bowen G.R. Millward and W. Jones J. Chem. SOC.,Faraday Trans. I 1983 79 1793; (b)S. E. Millman Synthetic Metals 1983 5 147. F Cl Br I At and Noble Gases with heat-treated petroleum coke between 610 and 733 K.1690 The reaction between F2 and the intercalation compound formed from graphite and AlF3 in the presence of F is an alternative synthesis;169b in both cases the content of (C,F) in the total graphite fluoride products are >60%. Both (C,F) and (CF) are used commercially as cathode materials in lithium batteries and their electrochemical properties have therefore received considerable attenti~n.'~' Their discharge characteristics in several non-aqueous solvents have been investigated dimethyl sulphoxide being the best of those examined.It is believed that solvated Lif is intercalated into the graphite fluoride layers by the electrode reaction and the total cell reaction may be represented by C,F + Li + zS- C,y(Li+ zS)F- (where S = solvent m~lecule).'~' Formation of a surface layer of graphite fluoride on the carbon anode during the electrolysis of molten KF,2HF is generally believed to be responsible for the high anodic overpotential for F2 ev~lution.'~' Supporting evidence for this contention is provided by mass spectrometric analyses of thermal decomposition products of graphite fluorides compared with anode materials. The anode surface layer is estimated to have the approximate composition CFI (a) N.Wantanabe Y. Ashida and T. Nakajirna Bull. Chem. SOC.Jpn. 1982,55,3197; (6) N. Watanabe T. Nakajima M. Kawaguchi and A. Izumi ibid. 1983 56 455. I70 N. Watanabe J. Fluorine Chem. 1983 22 205. 171 N. Watanabe R. Hagiwara T. Nakajima H. Touhara and K. Ueno Electrochim. Acra 1982 27 1615. 172 D.Devilliers M.Vogler F. Lantelme and M. Chemla Anal. Chim. Acta 1983 153 69.