0,S Se Te By F. J. BERRY School of Chemistry University of Birmingham P.0. Box 363 Birmingham B 15 277 1 Introduction The usefulness of the Group VI elements in the preparation of technologically important inorganic materials has continued to dominate interests in this area of chemistry. Studies of the new generation of 'warm' superconductors illustrate this very well since preparative solid state inorganic chemistry is central to the improve- ment of methods for the synthesis of the materials and is crucial to the search for new ceramic high temperature superconductors. It is now appreciated that the initial synthetic routes which often involved the use of high temperatures to decompose the reactant mixed oxides have tended to give materials in which the particle size is difficult to control and are not well suited for the fabrication of samples suitable for electrical experiments.Hence it is relevant to note the publication this year by teams active in this field of research of simpler synthetic routes for the preparation of yttrium-barium-copper oxides which should assist future developments in the synthetic chemistry of high- T superconductors in particular and solid state inorganic chemistry in general. A solution route to precursors of yttrium-barium-copper oxides has been described.' This method involves either the hydrolysis of stoicheiometric mixtures of Y(OCHMe2)3 Ba(OCHMe2)3 and a hydrolysable copper compound such as Cu(OCMe3) in tetrahydrofuran by water or the precipitation of the metals from mixed nitrate solutions with aqueous Na2N202.The precursors were converted to the finely powdered 123 tetragonal polymorph by heating at 650-700 "C in argon and were transformed to the orthorhombic phase by heating in oxygen at 400°C. The higher members of the homologous series such as YBa2Cu403 and Y,Ba4Cu7OI5 which have previously been synthesized under oxygen pressure of 200 atmospheres have been prepared2 by heating stoicheiometric mixtures of nitrates at 750 "C under flowing oxygen and then heating the precursor with Na2C03 or K2C03 under oxygen for three days at 800°C. Other attempts to prepare YB~,CU~O,-~ have involved the use of the precursors BaCuO and Y,CuO to give single phase product^.^ Another new method for the synthesis of yttrium-barium-copper oxide has involved the mixing by spray-drying ' S.Horowitiz S. J. McLain A. W. Sleight J. D. Druliner P. L. Gai M. J. Vankavelaar J. L. Wagner D. B. Biggs and S. J. Poon Science 1989 243 66. R. J. Cava J. J. Kajewski W. F. Pock B. Botlogg L. W. Rupp R. M. Fleming A. C. W. P. James and P. Marsh Nature 1989 338 328. R.-H. Choy W.-Y. Choe and Q. W. Choi Mat. Rex Bull. 1989 24 867. 21 22 F. J. Berry techniques of aqueous solutions of ionic salt precursor^.^ The anions in the spray- dried mixtures appear to participate in a low temperature exothermic oxidation- reduction reaction which converts the precursors into their corresponding mixed oxides and gives the single phase YBa2Cu30,- product by subsequent treatment at 910 "C for 10 minutes.Superconducting oxides in the form of powders or coatings have also been synthesized' from aqueous metal ethylenediaminetetraacetic acid (EDTA) solutions which were ultrasonically dispersed and converted to an aerosol of very fine droplets in an oxygen carrier stream. The submicron size oxide particles were collected by passing the aerosol through a tubular high temperature furnace. Another method of preparing high purity thin films of complex metal oxides by aerosol processes and which is applicable to the formation of ferroelectric and ferrimagnetic solids as well as superconducting materials has been achieved6 by the regulated deposition of ceramic powders from a gas phase suspension. Thin films of yttrium-barium-copper-oxide YBa2C~307-6 have also been fabri- cated by organometallic chemical vapour deposition techniques7 using tetramethyl- heptanedione complexes as source materials.The interaction of YBa2Cu307- and Bi,Sr2CaCu20 with zirconia alumina magnesia and strontium titanate has been investigated at temperatures close to those used for the synthesis of the superconduct- ing phases with a view to selecting suitable materials for use as substrates for high-T superconducting films. The foregoing gives some indication of the type of synthetic chemical studies now in progress on high temperature superconductors. It is also interesting to note the contribution of chemistry to theoretical aspects of superconductor research. For example a chemical model for high-temperature superconductivity which involves a two-stage chemical resonance mechanism has been proposed.' In this model attention was directed to implications for materials other than the now familiar cuprates and using the 70 K LaNiO based superconductor as an example the difficulties in preparation and chemical instability were explained in terms of the involvement of low-valent Ni' as the effective intermediate valance state.The treatment was extended to lone-pair systems e.g. Bi"' *Bi" and a conclusion drawn that many elements can give rise to high-T superconductivity and since metal- anion-metal distances are required to be small for high- T superconductors some of the more interesting compounds might require preparations under high pressure conditions. Analysis of the oxygen content of superconducting oxides has also attracted interest.A method involving the volumetric determination of oxygen in YBa2Cu307- has been reported" to have a reproducibility error of only A8 * 0.001. Another reported method" involved the slow cooling (1 "C/min) in oxygen of a sample heated to 930 "C and subsequent reduction under hydrogen in a thermobalance. K. Kourtakis M. Robbins and P. K. Gallagher J. Solid State Chem. 1989 82 290. A. Pebler and R. G. Charles Mat. Res. Bull. 1989 24 1069. T. T. Kodas Angew. Chem. Int. Ed. EngL Adv. Mat. 1989 28 794. ' K. Kanehori N. Sugii and K. Miyauchi J. Solid State Chem. 1989 82 103. D. Kovocheva K. Petrov and P. Peshev Mat. Res. Bull. 1989 24 1295. C. H. L. Goodman Mat. Res. Bull. 1989 24 1049.10 K. Conder S. Rusiecki and E. Kaldis Mat. Res. Bull. 1989 24 581. 'I S. P. Gorg R. Venkatararnani and S. Mazumder Mat. Rex Bull. 1989 24 803. 0,S Se Te 23 The chemical diffusion of oxygen in high density polycrystalline YB~,CU~O,-~ has been studied' by thermogravimetric techniques in the temperature range 550 to 850 "C under an oxygen pressure of 1 to lo- atmospheres. The chemical diffusion coefficient was found to be strongly sensitive to the oxygen composition. The enthalpy of oxidation of YBa,Cu,O (5.97 d x d 6.94) has been measured directly by high temperature reaction calorimetry and the partial molar enthalpy of oxygen dissolving in the structure found to be constant over the whole composition range.I3 The behaviour supports structural models in which the change in speciation from x = 6 to x = 7 is very gradual with Cu+ and Cu3+ coexisting in concentrations which vary smoothly with composition.The reaction kinetics for oxygen uptake into partially substituted YBa,Cu30 has been in~estigated'~ in materials of the type YIP,La Ba2Cu30, YBa2Cuz 5Feo 50,and Yo 5Nao ,Ba,Cu,O,. The reaction kinetics were found to decrease strongly on substitution at the copper site but to vary only slightly when substitution occurred at the rare earth site. Infrared reflectance spectroscopy Raman scattering and X-ray photoelectron spectroscopy have been used'5 to study the atmospheric degradation of YBa2Cu307-6. The degradation reaction 2YBa,Cu307 + 3co2 -+ Y,BaCuO + 5CuO + 3BaC0 + 0.50 was shown to be strongly catalysed by water vapour and to involve the build up of carbonate species in a matter of hours at room temperature.The influence of the copper and oxygen valence states in YBa,Cu307 on stoicheiometry and the interaction of the compound with water has also been studied by X-ray photoelectron spectroscopy.16 Gas chromatography-mass spectrometry have been used'7 to analyse the oxygen evolved from YBa2C~30698 when it is dissolved in acid and the results interpreted in terms of some of the lattice oxygen being present as 0-or peroxide ions. The superconducting BiSrCaCu,O,( T 80-1 10 K) phase has been prepared by a novel sol-gel process using oxalate as the complexing agent.I8 High density single phases of BiSrCaCu,O and Bi,Sr,Ca,Cu,O have been prepared by annealing the amorphous precursors which were obtained by quenching from melts." The super- conducting and structural properties of the solid solution series Bi,-,Pb,Sr,Ca,_,Y,Cu,O where 0 d x S 1 have also been reported.,' The com- pound Bi 04Sr1 76Mg0 3oCuo 9o06has been synthesized and shown to undergo a 20 low (6 K) superconducting transition.21 The structural and superconducting (T -107 K) properties of Bi2Sr2(Mi- M~),Cu30 (M' = Ca Y; M" = Na Ca) including hydrided materials have also been described.,' Other studies which illustrate the '' K.Kishio K. Suzuki T. Hasegawa T. Yamamoto and K. Kitazawa J. Solid Stare Chem. 1989,82 192. l3 M. E. Parks A. Navrots:.y K. Mocala E. Takayama-Muromachi A. Jacobson and P. K. Davies J. Solid State Chem.1989 79 53. l4 B. E. Higgins and H. Oesterreicher Mar. Res. Bull. 1989 24,739. l5 R. G. Egdell W. R. Flavell and P. C. Hollamby J. Solid Stare Chem. 1989 79 238. 16 P. Salvador J. L. G. Fiesso J. Amodor C. Cascales and I. Rasines J. Solid Stare Chem. 1989 81 240. M. W. Shafer R. A. de Grout M. M. Plechaty G. J. Scilla B. L. Olson and E. I. Cooper Mar. Res. Bull. 1989 24 687. V. Slusarenko K. R. Thampi and J. Kiwi J. Solid State Chem. 1989 79 277. 19 H. Sato W. Zhu M. M. Miller T. Ishiguro A. I. Schindler and C. S. Calhoun J. Solid State Chem. 1989 79 146. 20 R. Retoux V. Caignaert J. Provost C. Michel M. Hervieu and B. Raveau J. Solid Stare Chem. 1989 79 157. W. Urland and F. Tietz Mar. Res. Bull. 1989 24 489. l2 M. G. Smith and H.Oesterreicher Mar. Res. Bull. 1989 24 1103. 24 F. J. Berry type of copper-containing superconducting compounds which have attracted recent interest include T1,,5Pbo.5CaSr2Cu20~3 (Y1-xCa,)Ba2Cu30624 Nd2-xThxC~025 Lal+xSr2-xCu205.5+~6 It must be emphasized that many other and GdBa2C~30x.27 variants of the copper-containing superconductors mentioned above have been examined and that the literature on this area of chemistry is considerable and not amenable to comprehensive review. As mentioned earlier non-copper containing superconducting oxides are also attracting attention. It is especially interesting to note the prediction2* that some layered perovskite-related Aurivillius-type phases which have strikingly similar structures to those of the Bi-Ca-Sr-Cu-0 and T1-Ca-Ba-Cu-0 superconductors might form a new class of superconductors.The report29 that the critical temperature for superconductivity in the cubic perovskite (Ba K)Bi03 system has been increased to 34 K demonstrates that oxides not containing copper but with two dimensional structural properties are worthy of attention. Hence it is clear that the current level of chemical activity in studies of the synthesis structural properties and reactivity of oxide superconductors remains high and is producing fundamental solid state chemical information which will doubtless encourage further work in related systems. 2 Oxygen The first successful time-resolved detection of singlet oxygen luminescence using pulse radiolysis techniques has been rep~rted.~' A very sensitive infrared emission spectrometer with very low excitation powers has been used3' to determine lo2 lifetimes directly from phosphorescence decay in various chlorine- bromine- or iodine-substituted perfluorinated solvents and the data used to assess the influence of heavy atom substituted solvents on radiationless deactivation.The electronic structure of ozone has been examined32 and Jahn-Teller effects in its photodissoci- ation identified. The reaction of titanium sulphur and sulphur monochloride has been found33 to give the compound Ti40( S2)&1 which contains an oxygen-centred tetranuclear flattened titanium tetrahedron as shown in Figure 1. It is interesting to note the synthesis34 and characterization of a soluble oxide inclusion complex of composition [CH3CN(VI2O:,)] that has some molecular analogy to solid microporous oxides such as zeolites which are well known for their ability to reversibly absorb small covalent molecules in a size- and shape-selective fashion.23 A. K. Ganguli K. S. Nanjundaswanny C. N. R. Rao A. Sequeira and H. Rajagopal Mat. Res. Bull. 1989 24 883. 24 E. M. McCarron M. K. Crawford and J. B. Parise J. Solid State Chem. 1989 78 192. 25 T. C. Huang P. W. Wang E. Moran A. I. Nazzal and J. B. Torrance Mat. Res. Bull. 1989 24 875. 26 D. M. De Leeuw C. A. H. A Mutsaers G. P. J. Geelen and C. Langereis J. Solid Sfate Chern. 1989 80 276. 27 H. Shibahara L. D. Marks S.4. Hwu and K. R. Poeppelmeier J. Solid Srafe Chern. 1989 79 194.28 K. A. Yee T. A. Albright D. Jung and M.-H. Whangbo Angew. Chem. Inf. Ed. Engl 1989 28 750. 29 N. L. Jones J. B. Parise R. B. Flippen and A. W. Sleight J. Solid State Chem. 1989 78 319. 30 A. A. Gorman I. Hamblett and E. J. Land J. Am. Chem. SOC.,1989 111 1876. 31 R. Schmidt J. Am. Chem. Soc. 1989 111 6983. 32 D. J. Tannor J. Am. Chem. Soc. 1989 111 2772. 33 F. A. Cotton X. Feng P. A. Kibola and R. A. Sandor J. Am. Chem. Soc. 1989 111 2148. 34 V. W. Day W. G. Klemperer and 0.M. Yaghi J. Am. Chem. Soc. 1989 111 5959. 0 S,Se Te Figure 1 Structure of Ti,O( S2)& (Reproduced by permission from J. Am. Chem. SOC.,1989 111 2150) 3 Sulphur The reaction of hydroxide ions with elemental sulphur (s,)in aprotic solvents has been shown35 to give the trisulphur anion radical S,' as the major product.The reaction stoicheiometry (eight -OH per three S8 to give eight S;) was found to be consistent with the results for the electrochemical reduction of s8 in dimethyl sulphoxide and acetonitrile. In continued studies of polychalcogenide synthesis in molten alkali metal polysulphide solvents two novel one-dimensional compounds containing Si-ligands have been formed from the K-Cu-S system.36 The understanding of solutions of sulphur in liquid ammonia continues to attract interest. In one report3' UV-visible spectroscopy was used to monitor the solubiliz- ation process of sulphur in liquid ammonia and the concentration of the species S3N-shown to proceed through a maximum and to be the precursor species of S4N-.The addition of ammonium chloride to ammonia was found to slow down the first steps of the solubilization whilst the opposite effect was found when alkali amide was added to ammonia. Another report3 described some Raman spectro- scopic investigations and photochemical observations of solutions of sulphur in liquid ammonia. The study of sulphur-nitrogen compounds remains a significant area of activity in sulphur chemistry. The addition of SCI, SOQ S02C12 or SeCI to liquid ammonia followed by Pt( PR3),Cl has been shown39 to give complexes of the type R(s2N2)(pR3)2 Pt(NS0)2(pR3)2 R[(HN),SOdPR3)2 and R(Se2N2)(PR3)2 respectively. The reaction of [S4N3]CI or [S3N2CI]CI in liquid ammonia with 35 M. Hojo and D.T. Sawyer Inorg. Chem. 1989 28 1201. 36 M. G. Kanotzidis and Y. Park J. Am. Chem. SOC.,1989 111 3767. 37 P. Dubois J. P. Lelieur and G. Lepoutre Znorg. Chem. 1989 28 195. 38 P. Dubois J. P. Lelieur and G. Lepoutre Znorg. Chem. 1989 28 2489. 39 1. P. Parkin A. M. 2.Slawin D. J. Williams and J. D. Woolins J. Chem. SOC.,Chem. Commun. 1989 1060. 26 F. J. Berry [PtC12(PR3),] or [(L-L')PdCl,Pd(L-L')] where (L-L') is a C-N ligand has been shown4' to give [Pt(S,N,)(PR,),] and [Pd(S,N,H)(L-L')] respectively. In some cases complexes containing S3N- ligands were also obtained. The N2S4 donor complex [Cu(L')I2+ where L' is 1,4,10,13,-tetrathia-7,16-diazacyclo-octadecane has been found4' to show a chemically reversible cop- per(II)/(r) couple at El/ -0.31V w FJF; (ferrocene/ferrocenium) whereas the methylated analogue [Cu( L2)I2+ where L2 is 7,16-dimethyl-l,4,10,13-tetrathia-7,16~ diazacyclo-octadecane shows a more anodic copper(Ir)/(I) couple at E,, + 0.06V us F,/F:.The differences in redox potential were related to the stereochemical features of the copper( 11) complexes the crystal structures of which were determined for [Cu( L1)I2+ and [Cu2(L2)( NCMe)2]2+. The dehalogenation of [S4N3]Cl and [S5N5]Cl by 4-phenyl-1,2,3,5-dithiadiazoledimer (PhmN) in acetonitrile has been found4 to be accompanied by novel ring contractions to give the compounds [PhCNSSN][ S3N2]Cl and [(PhmN),Cl][ S3N3]. Ab initio self-consistent field molecular orbital calculations have been used4 to examine novel stereoelectronic effects in linear R2S3N2 and cyclic XS3N2 systems.The compound 1,3,5-trithia-2,4,6- triazapentolenyl has been suggested4 as a likely candidate for the synthesis of conductive systems. The stable sulphur-nitrogen radical which is arranged in stacks in the solid state was obtained by a multistep synthesis and found to have weak S. -.S interactions between stacks but negligible interactions within the stack. The reaction of Pt(C,H,)(PPh,) with 1,5-E2N4S2 (E = Ph2P Me2NC) in acetonitrile has been shown4' to produce high yields of Pt(1,5-E2N4S2)(PPh3), in which the q2-S,S'bonding between platinum and the heterocyclic ligand is analogous to that found in T2-alkene-platinum complexes. The reaction of S4N402 with PtCl,(PMe,Ph) in liquid ammonia has been found46 to give the compound Pt(PMe2Ph),[ S2N3( SO2)(NH,)] which is the first example of a PtS2N3 ring system and which was shown to consist of a square planar platinum(r1) with a puckered PtS2N3 ring (Figure 2).The reaction of the polymer n(SnCl,S,N,) or the dimer (SnMe2S2N2) with chloride ions has been shown4' to produce salts of the SnC14S2N;- or SnMe2C1S2N anions respectively. X-ray structural determinations showed the anions to ,contain the five-membered SnS2N2 ring. Dimeric aryl- dithiadiazoles (RCNSSN)2 (R = Ph or p-ClC6H4) have been found48 to undergo nitrogen insertion into the S-S bonds and to form the corresponding dithiatriazine dimers when treated with atomic nitrogen which was generated in a cool direct current plasma. The alkyl derivatives (R = Me Pr or But) gave polymeric products whilst the dithiadiazolylium salts [RCNSSk]+X- (R = Ph or p-CIC6H4; X = I 40 C.A. O'Mahoney I. P. Parkin D. J. Williams and J. D. Woollins J. Chem. Soc, Dalton Trans. 1989 1179. 41 N. Atkinson A. J. Blake M. G. B. Drew G. Forsyth A. J. Lavery G. Reid and M. Schroder J. Chem. Soc. Chern. Comrnun. 1989 984. 42 A. J. Banister W. Clegg Z. V. Hauptman A. W. Luke and S. T. Wait J. Chem. Soc. Chern. Commun. 1989 351. 43 R. M. Bannister and H. S. Rzepa J. Cheni. SOC.,Dalton Trans. 1989 1609. 44 G. Wolmershauser and R. Johann Angew. Chem. Int. Ed. Engl. 1989 28 920. 4s T. Chivers K. S. Dhathathreyan and T. Ziegler J. Chern. SOC. Chem. Commun. 1989 86. 46 I. P. Parkin A. M. Z. Slawin D.J. Williams and J. D. Woollins J. Chem. SOC.,Chem. Commun. 1989 58. 47 T. Chivers J. Fait and K. J. Schmidt Inorg. Chem. 1989 28 3018. 48 A. J. Banister M. I. Hansford Z. V. Hauptman S. T. Wait and W. Clegg J. Chem. SOC.,Dalton Trans. 1989 1705. 0,S Se Te a Figure 2 The X-ray crystal structure of Pt(PMe2Ph),[S,N,(S0,)( NH,)] (Reproduced by permission from J. Chem. SOC.,Chem. Commun. 1989 58) Br CN or S3N3) reacted with the nitrogen plasma to give high yields of the respective dithiatriazine (RCN3S2),. The reaction of (Me3SiN)Ph2PN( Ph)C( NSiMe,) with sulphur dichloride has been shown49 to give the 1,3,2,4,6-thiaphosphatriazine Ph2P( Ph)CN,SCl which upon reduction with triphenyl antimony gives the corre- sponding thiaphosphatriazinyl radical [Ph2P( Ph)CN3S]'.The ESR spectrum recor- ded from the radical showed the spin distribution to be heavily localized over the (P)-N-S region of the ring. Skeletal scrambling in the 1,3-NSN-bridged 5-phenyl-l,3,2,4,6-dithiatriazine (PhCN,S,) has been studied by NMR spectros~opy.~~ A mechanism involving two simultaneous 1,3-nitrogen shift pathways via carbon and sulphur was proposed and supported by comparing the observed depletion/enrichment rates with those predic- ted by a model based on two sets of coupled first-order site exchanges. The molecular geometry of Me,SiNSNSiMe3 in the gas phase has been studied by electron diffrac- tion and the molecule shown to possess C2 symmetry with a distorted syn syn c~nformation.~' The crystal structure of 2,7,9,14-tetrakis( diethylamino)- 3,5,6,10,12,13-hexathia-1,8-diaza-2,4,7,9,11,14-hexaboratricyclo[9.3 .0.043s] tetra- decane was described during a study of the synthesis and characterization of mono- bi- and tri-cyclic boron-nitrogen-sulphur ring systems.52 Attempts to prepare novel compounds with layered structures have resulted in the identification of a new quaternary paramagnetic compound of composition MnGa2xCr,-2xS4 (0.75 < x < 0.9) with a layered Znln2S (1IIa)-type str~cture.~ Magic-angle spinning ,*PNMR spectra recorded from the solid binary phosphorus sulphides P,S,(n = 3,5,7,9 or 10) have been reported and the multiplicity of the 49 A.W. Cordes H. Koenig and R. T. Oakley J. Chem. SOC.,Chern. Commun. 1989 710. 50 K. T.Bestari R. T. Boere and R. T. Oakley J. Am. Chem. SOC.,1989 111 1579. " D. G. Anderson H. E. Robertson D. W. H. Rankin and J. D. Woollins J. Chem. SOC.,Dalton Trans. 1989 859. 52 A. Kendrick H. Noth B. Stalla and W. Storch J. Chem. SOC.,Dalton Trans. 1989 1311. 53 H. Haeuseler and W. Kwarteng-Acheampong Mat. Rex Bull. 1989 24 939. 28 F. J. Berry 31 P resonances correlated with the structural inequivalences revealed by X-ray diifra~tion.'~ The collapse of the PB parts of the 31P NMR spectra of a-tetraphos- phorus trisulphide isothiocyanates at room temperature has been associated with 14N relaxation effects as opposed to chemical exchange processes.55 Salts of the first dithiaphospholium cation have been isolated and characterized as aromatic deriva- tive~.~~ X-ray crystal structure of 1,3,2-benzodithiaphospholium tetra-The chloroaluminate showed a planar geometry for the cation with short P-S bonds and together with spectroscopic data were interpreted in terms of unique 3prr-3prr bonding across the S-P-S moiety.It is interesting to note the attention being given to metal phosphorus trisulphides and the report of a novel tetrathiafulvalene- MPS3 (M = Mn Cd) layered composite material.57 In these studies hydrated potassium intercalates M1-,PS3K2x(HZO)y (M = M Cd) which were derived from MPS3 lamellar materials were reacted with (TTF),( BF4)2in MeCN to yield lamellar composites in which the tetrathiafulvalene (lTF) species were intercalated between the Ml-,PS3 slabs. The synthetic approach is worthy of note since it suggests a strategy to develop a class of new materials merging the fields of layered inorganic materials and organic metals.Studies of the reactions of sulphur dioxide with photochemically generated polypyridyl complexes of chromium( 11) have shown5* that three reactions occur when Cr(NN):+ ions (NN = bpy phen and substituted analogues) are subjected to visible light from a laser pulse in solutions containing SO2in 1.OM H2S04. The quenching reaction produces Cr( NN):+ which subsequently undergoes back electron transfer but in the presence of millimolar concentrations of SO2 the predominant reaction is electron transfer between Cr( NN):' and SOz to give the transient SO species. The reaction between sulphur dioxide and dry trimethylamine oxide has been re-in~estigated~~ with the most reactive product (CH3),( H)NCH2S03 being structurally characterized and its iodine oxidation and Lewis acid chemistry being subjected to further examination.The He1 photoelectron spectra of gaseous com- plexes formed by sulphur dioxide with the electron donors trimethylamine triethyl- amine diethyl ether and diethyl sulphide have been recorded and interpreted.60 Kinetic and spectroscopic evidence has been presented for the formation and decomposition of iron( m)sulphur( IV) transients during the iron( 111) catalysed autoxidation of sulphur( IV) oxides in aqueous solution.6' Four different reaction steps were identified as possible stages relevant to acid rain formation. The crystal structure of zinc thiogallate of composition ZnGa,S4 which can be used as an infrared window has been redetermined6 and shown to involve a disordering of the zinc and gallium ions.Two ternary compounds of composition Li2SiS and Li4SiS4 have been identified in the lithium-silicon-sulphur system63 and 54 R. K. Harris P. J. Wilkes P. T. Wood and J. D. Woollins J. Chem. SOC.,Dalton Trans. 1989 809. 5s B. W. Tattershall J. Chem. SOC.,Chem. Commun. 1989 216. 56 N. Burford B. W. Royan A. Linden and T. S. Cameron Inorg. Chem. 1989 28 144. 57 P. Lacroix J. P. Audiere and R. Clement J. Chem. Soc. Chem. Commun. 1989 536. 58 C. A. Simmons A. Bakac and J. H. Espenson Znorg. Chem. 1989 28 581. 59 A. B. Burg Inorg. Chem. 1989 28 1295. 6o T. Pradeep K. S. Sreekanth M.S. Hegde and C. N. R. Rao J. Am. Chem. SOC.,1989 111 5058. 61 J. Kraft and R. van Eldik J. Chem. SOC. Chem. Commun. 1989 790. 62 G. B. Carpenter P. Wu Y.-M. Gao and A. Wold Mat. Rex Bull. 1989 24 1077. 63 B. T. Ahn and R. A. Huggins Mat. Res. Bull. 1989 24 889. 0,S Se Te 29 their lithium ionic conductivities associated with their crystal structures. A matrix infrared spectroscopy in solid argon of molecular SiS2 generated by a reaction of SiS with atomic sulphur has been performed to examine the bonding and structural properties of SiS. The structure of Sn(CH3),Br. C4H6N2S has been found to consist of trigonal-bipyramidal molecules held together in pairs by two N -Ha -Br hydrogen bonds and with the ligand bonded to the metal through the sulphur atom.65 The reaction of Na2S.9H20 with 1,1,2,2,-tetra(2,4,6-tri-isopropylphenyl)-l,2-dibromoditin in air has been found66 to yield the sterically hindered four-membered l-oxa-3-thia-2,4-distannetane ring which is a distorted rhombohedron containing distinct Sn-S and Sn-0 bonds whereas the same reagents react under anaerobic conditions to give the corresponding 173-dithia-2,4-distannetane.A three-membered 1-thia-2,3-distannirane was postulated as being the common intermediate in the two reactions. Powder X-ray diffraction has been to study chemically twinned phases in the PbS-rich region of the Ag,S-PbS-Bi2S3 system. Six structures were characterized and a new phase built up of galena-like slabs was identified. Molecular- size PbS species have been68 stabilized in the open-pore structure of zeolite Y and mordenite via ion exchange with Pb(I1) and subsequent treatment with H2S at 295 K.Detailed analysis of the lead L,,,-edge X-ray absorption data showed that intrazeolite Pb02(Oz)3 (0 = zeolite oxygen) species in zeolite Y react with H2S to form monomolecular S,Pb(O,) species which are anchored to the zeolite framework. The intrazeolite PbS phase appeared to be more ordered at high loading levels of lead in zeolite Y. The coordination of Pb(I1) and the structure of PbS in the mordenite host was less ordered but similar to that of the monomolecular species in zeolite Y. The structure of K2[Pb{S2C=C(CN),},].2 H20 has been determined69 and found to consist of one-dimensional [Pb(S2C=C(CN),},l2-anions stacked along the crystallographic b direction.The preparation of 5-methyl-1,3,2-benzodithiarsolium and 5-methyl- 1,3,2- benzodithiastibolium cations has been and the naphthalenic nature of the compounds associated with the presence of unique prr-p~bonding of sulphur to arsenic and antimony. The compound tetraphenylphosphonium tetraiodotrithiotriarsenate PPh4[ As3S314] has been prepared from the reaction of As2S3 PPh41 and HI in CH212 at 80 "C and the [As3S314]- ion found by X-ray crystallography to consist of an As3S3 ring in the chair c~nformation.~~ The structures of gaseous trifluoromethylsulphurane CH3SF3 and trifluoro(tri- fluoromethyl)sulphurane CF3SF3 have been determined by electron diffra~tion~~ and both molecules shown to adopt trigonal bipyramidal structures centred on the sulphur atom.Caesium fluoride activated by thermal decomposition of its 1 :1 64 H. Schnockel and R. Koppe J. Am. Chem. SOC.,1989 111 4583. 65 G. Valle A. S. Gonzalez U. Vettori and R. Ettorre J. Chem. SOC.,Dalton Trans. 1989 927. 66 P. Brown M. F. Mahon and K. C. Molloy J. Chem. SOC.,Chem. Commun. 1989 1621. 67 A. Skowron and R. J. D. Tilley J. Solid State Chem. 1989 78 84. K. Moller T. Bein N. Herron W. Mahler and Y. Wang Inorg. Chem. 1989 28 2914. 69 H.-U. Hummel and H. Meske J. Chem. SOC.,Dalton Trans. 1989 627. 70 N. Burford and B. W. Royan J. Chem. SOC.,Chem. Commun. 1989 19. 71 N. Burford and B. W. Royan J. Am. Chem. SOC.,1989 111 3746. 72 H. Sinning and U. Muller 2. Anorg.AIlg. Chem. 1989 568 49. 73 A. J. Downs G. S. McGrady E. A. Barnfield D. W. H. Rankin H. E. Robertson J. E. Boggs and K. D. Dobbs Inorg. Chem. 1989 28 3286. 30 F. J. Berry adduct with hexafluoroacetone or carbonyl fluorides has been shown74 to react with SF4 at room temperature and by using radiotracer experiments involving 18F and 3sS the occurrence of weakly adsorbed SF4 at the surface of activated CsF has been identified. Tetrathiafulvalene (TTF) and its derivatives continue to be the most investigated donors for the generation of organic metals and superconductors. Pressed polycrys- talline samples of p-(BEDT-TTF),13 have been found75 to exhibit bulk superconduc- tivity with an onset temperature of 9 K and with zero resistivity being observed at 3.2 K.The synthesis and structure of bis(ethylenedioxy)tetrathiafulvalene,which is the first oxygen-substituted tetrathiafulvalene has been rep~rted'~ which gives scope for checking whether oxygen radical cations have relevance to the new ceramic oxide superconductors. The compound bis( phenylethylenedithi0)-tetrathiafulvalene (BPhEDT-TTF) has been synthesized7' and some electrochemically prepared salts of the new ?r-donor have been described. Synchrotron radiation has been used to collect EXAFS data from a series of naturally occurring and synthetic tetrahedrite (Cu Ag),,(Cu Fe Zn Cd)2Sb4S13 minerals7' and the results interpreted in terms of the coordination environment of the various metals and preferentially occupied sites. The results complement crys- tallographic data by giving information about each element in sites occupied by more than one cation and demonstrate the value of multi-element EXAFS in the investigation of a chemically and structurally complex mineralogical system.Photodissociation collision-induced dissociation ion-molecule reactions and kinetics experiments have been used to study the series FeS:(n = 1-6) generated from sequential reactions of Fe+ with ethylene sulphide in the gas phase.79 Studies of iron-sulphur compounds with compositions relevant to interests in protein chemistry have continued. For example a new development of single-crystal ENDOR studies of an s7Fe-enriched iron-sulphur [Fe4S4I3+ cluster have been described." Studies of alternative spin states in synthetic analogues of [Fe4S4]+ clusters have continued" and the structure of (Et4N)3[ Fe,S,( S-o-C,H,SBu'),] con-taining a reduced cluster with a compressed tetragonal distortion have been described." The first examples of bridged Fe,S double cubanes have been pre- paredg2 by exploiting the site-specific substitution property of the previously reported single cubane cluster [Fe4S4( L.S3)C1I2- where L.S3 is 1,3,5-tris[4,6-dimethyl-3-mercaptophenyl thio]-2,4,6-tris( p-tolylthio) benzene.3- The clusters were examined by cyclic-and differential-pulse voltammetry to investigate electron-transfer coupling across sulphur-containing bridges of variable length.The occurrence of electrochemical carboxylation coupled with nitrite reduction catalysed by 74 K.W. Dixon and J. M. Winfield J. Chem. SOC.,Dalton Trans. 1989 937. 75 D. Schweitzer E. Gogu H. Grimm S. Kahlich and H. J. Keller Angew. Chem. Inf. Ed. Engl. Adv. Mater. 1989 28 953. 76 T. Suzuki H. Yamochi G. Srdanou K. Hinkelmann and F. Wudl J. Am. Chem. SOC.,1989,111,3108. 77 K. S. Varma J. Evans S. Edge A. E. Underhill G. Bojeson and J. Becher J. Chem. SOC.,Chem. Cornmun. 1989 257. 78 J. M. Charnock C. D. Garner R. A. D. Pattrick and D. J. Vaughan J. Solid State Chem. 1989,82 279. 79 T. J. MacMahon T. C. Jackson and B. S. Freiser J. Am. Chem. SOC.,1989 111 421. 80 G. Rius and B. Lamotte J. Am. Chem. SOC.,1989 111 2464. '*M. J. Carney G. C. Papaefthymiou R. B. Frankel and R. H. Holm Inorg. Chem. 1989 28 1497. 82 T. D. P. Stack M.J. Carney and R. H. Holm. J. Am. Chem. SOC.,1989 111 1670. 0,S Se Te 31 [Fe,S,( SPh),]’+ and [Mo2Fe6S8( SPh)9]3- has been in~estigated.~~ Double-cubane clusters with the ReFe3S4 core have been assembled during studies of the stability range of heterometal cubane-type clusters.84 The previously synthesized and struc- turally characterized cubane-type cores [VFe3S4I2+ and [MoFe3SJ3+ have been inserted into the semirigid trithiolate cavitand ligand LS3 (1,3,5-tris(4,6-dimethyl-3-mercaptophenyl)thio)-2,4,6-tris(p-tolylthio) benzenate3- with the identification of regiospecific reactions at a vanadium site similar to that in nitrogena~e.~~ Both [NBu;],[ MoFe3S4( SPh)3( o-02c6c14)]2 and [NBu:l2[Fe4S4( SPh)4]- modified glassy carbon electrodes have been foundg6 to catalyse the multielectron reduction of HOC2H,N3 to give HOC2H4NH2 N, N2H4 and NH in water.The preparation and spectroscopic characterization of metal-sulphur clusters such as R2(NH4)-[CU~SI 21 R2 [cU4s 121’CH3CN R2[ CU4s12,g 1 R2[ (s5)21 R2[Fe4S4Br41 R2[ Fe,S,Br2C12] R2[ Fe4S4C14] R2[Fe2S2C14] where R = PPh, and of [Fe( DMF)6]- [Fe2S2C14] by the simple reaction of metal salts with H2S has been described.87 Vibrational spectra and normal mode analysis for Fe2S2 protein analogues together with resonance Raman spectral studies of structural variations among adrenodoxin and ferrodoxin have been rep~rted.~’*~~ The reaction of (5H,14H-6,8,15,17-tetramethyldibenzo[ b i][ 1,4,8,1 lltetra- azacyc1otetradecinato)-iron(11) [Fe(tmdbtd)] with elemental sulphur under very mild conditions in tetrahydrofuran(THF) has been shown” to give quantitative formation of the corresponding p-sulphido complex [{Fe(tmdbtd)},( p-S)]-THF in which the macrocyclic ligand adopts a saddle shape.The reactions of the sulphur- bridged metal cluster complexes M3(CO),(p3-CO)(p3-S) where M = Fe Ru or Os with W(CO)6 and W(CO)5(PMe2Ph) in the presence of ultraviolet radiation has yielded” the new mixed-metal cluster complexes M,W(CO),,L( p3-S),where L is CO PMe2Ph and OS~W(CO)~~(PM~~P~)~(~~-S). The reaction of OS~(CO)~~(~,-S) with W(CO)5(PMe,Ph) in the presence of ultraviolet radiation gave the new mixed metal cluster complex OS,W(CO)~~(PM~~P~)(~~-S). The reaction of a range of transition -metal carbonyl anions [MI- with 2-chloro-l,3,2-dithiarsolane has been shown to resultg2 in the formation of the metalloarsines [M-AsSCH2CH2S] where M-is [Mo(CO)3(rl-C5H5)]- [W(C0)3(77-C5H5)1- [Fe(CO)2(r7-c,H5)1- [Mn(CO),]-or [Re(CO),]-.Studies of the kinetics and mechanism of the iron( IrI)-catalysed autoxidation of sulphur(IV) oxides have been developed by examining the complex formation reactions which occur between equated Fe(II1) and S(IV) oxides using techniques such as chromatography UV -vis and FTIR spectroscopy and stopped flow kinetics 83 K. Tanaka R. Wakita and T. Tanaka J. Am. Chem. Soc. 1989 111 2428. 84 S. Ciurli M. J. Carney R. H. Holm and G. C. Papaefthymiou Znorg. Chem. 1989 28 2696. 85 S. Ciurli and R. H. Holm Inorg. Chem. 1989 28 1685.86 K. Tanaka S. Uezumi and T. Tanaka J. Chem. Soc. Dalton Trans. 1989 1547. 87 A. Muller N. H. Schladerbeck E. Krickemeyer H. Bogge K. Schmitz E. Bill and A. X. Trautmein Z. Anorg. Allg. Chem. 1989 570 7. 88 S. Han R. S. Czernuszewicz and T. G. Spiro 1.Am. Chern. SOC.,1989 111 3496. 89 S. Han R. S. Czernuszewicz T. Kimura M. W. W. Adams and T. G. Spiro J. Am. Chem. Soc. 1989 111 3505. 90 P. Berno C. Floriani A. Chiesi-Villa and C. Guastini J. Chem. SOC.,Dalton Trans. 1989 551. 91 R. D. Adams J. E. Bobin P. Mathur K. Natarojan and J.-G. Wang Inorg. Chem. 1989 28 1440. 92 E. W. Abel S. R. Allen and B. Khandelwal 1.Chem. Soc. Dalton Trans. 1989 885. 32 F. J. Berry experiment^.^^,^^ Evidence was reported93 for the stepwise formation of 1:1 1 :2 and 1 :3 sulphito complexes depending on the pH and concentration of the S(IV) oxides used.The mono- bis- and tris(su1phito) complexes of Fe(rI1) were shown9 to undergo two successive redox reactions and produce Fe(rr) SOf ,and S202-. The mechanistic aspects of the decomposition reactions were related to the nature of the initial complexes. The solution chemistry of the green aqua ion of cuboidal mixed valence Mo4S? in [MO~S~(H~O)~~]~+ where the average oxidation state is 3.25 has been in~estigated~~ and the molybdenum/sulphido cluster shown to exhibit remarkable stability in acidic solutions p-toluenesulphonic acid (HPTS) and HClO,. In a subsequent the green sulphide-bridged Mo;" ion [Mo3S4( H20)9]+ was prepared by decomposition of the cuboidal [MO~S~(H~O)~~]~+ and found to exhibit a solution chemistry which is strikingly different from that of the previously studied red [Mo304( H20)9]4+.The sulphur-bridged incomplete cubane type aqua ion [MO~S,(H~O)~]~+ has been shown97 to react with metallic tin and with tin(1r) to give [(H20)9M03S4SnS4M03( H20)9]8+ and Mo,SnS,.( aq)6+ respectively. The aqua ion [Mo~S,(H~O)~]~+ was found to react with metallic iron nickel copper mercury and magnesium but not with the divalent ions of the metals. The diphos (Ph2PCzH4PPhz) complexes of the Mo,S:+ core with p-tolylimido dithiophosphate and carboxylate coligands have been prepared and ~haracterized.~~ Three new trinuclear molybdenum-containing clusters have been prepared and structurally ~haracterized.~~ The compounds Mo3(p3-S)(p-S),Cl,( PPh3)+ (H20)z.3THF and [Mo3(p3-S)(p-S)3Cl,(dmpe)3]C1-2MeOH were prepared by reacting Mo3S7C14 with the corresponding phosphine ligands at room temperature in THF.The formation of the compound W3S7Br4 was achieved by heating stoicheiometric quantities of the elements in sealed tubes and was shown by X-ray crystallography to adopt a trinuclear structure (Figure 3) which is isomorphous with Mo3S7C1,. Fenske-Hall molecular orbital calculations have been used"' to examine the electronically induced conformational changes which occur in high valent bimetallic chalcogen complexes of the type [CpML],(p-L) where M =Mo Re and L =S 0.A theoretical study of the bonding in sulphur- and oxygen-containing molybdenum species of general formula MoS,O;T (n =04)has discussed the types of bonds that are expected to develop between the central molybdenum atom and the ligand orbitals."' An investigationlo2 of the oxidative transformations of [MoOS812- has led to the characterization of the MO(VI) 0x0 disulphido complexes [Mo2O2S9I2- and [MO,O~S~,]~-as a solid mixture in the structure of (Et4N)2[Mo202S9.14].The oxidative coupling of (Et4N),[ gave the MO(VI) linear tetramer (Et4N)2[Mo404S,8] which on reaction with NiC12 in MeCN 93 J.Kraft and R. van Eldik Inorg. Chem. 1989 28 2297. 94 J. haft and R. van Eldik Inorg. Chem. 1989 28 2306. 95 B.-L. Ooi C. Sharp and A. G. Sykes J. Am. Chem. SOC.,1989 111 125. 96 B.-L. Ooi and A. G. Sykes Inorg. Chem. 1989 28 3799.97 H. Akashi and T. Shibahara Inorg. Chem. 1989 28 2906. 98 A. C. Lizano J. F. Richardson and M. E. Noble Inorg. Chem. 1989 28 1451. 99 F. A. Cotton P. A. Kibala M. Matusz C.S. McCaleb and R. B. W. Sandor Inorg. Chem. 1989,28,2623. 100 B. E. Bursten and R. H. Clayton Inorg. Chem. 1989 28 2846. 101 B. D. El-Issa A. A. M. Ah and H. Zanati Inorg. Chem. 1989 28 3297. 102 A. 1. Hadjikyriacou and D. Coucouvanis Inorg. Chem. 1989 28 2169. 0 S Se Te S(1) Figure 3 Structure of the W,S,Br4 molecule (Reproduced by permission from Inorg. Chem. 1989 28 2623) gave the new chloro derivative (Et4N)[Mo202S,C1] as a result of ligand exchange. The structure of 42- and 44-electron (P2M2(C0)4(p-E)2 butterfly complexes (M = Cr Mo W; E = S Se SR PR) and related compounds have been rationalized on the basis of EH-MO calculations.'03 The possible existence of cis/ trans conforma-tions of the Cp and CO ligands was analysed together with an assessment of M-M versus E-E bonding in the 42 electron species.The interconversion between isomers was considered and the electrochemical behaviours of the [Cp2M02( p-SR)2]o'2+ complexes investigated. The compound of composition MO~(C~H&)S which is the purple product in molybdenum-dithiol reactions has been shown'04 to adopt a novel molybdenum(v) dimer dithiolate structure (Figure 4). The photoresponse behaviour of the polycrystalline tetrahedral metal-cluster chalcogenides GaMo4S and ZnMo2Re2S has been attrib~ted''~ to the Mo d-d transition with n-type character.The compounds were found to give photoresponse in aqueous acidic and alkaline solutions in 12/1- and Fe(CN)2-/3- redox electrolyte. The hexanuclear tungsten complex octakis(p3-sulphido)hexakis(triethylphos-phine)hexatungsten of composition [w6&(PEt3)6j has been synthesizedlo6 from the reaction of magnesium metal with a trinuclear tungsten chloro sulphido cluster compound prepared from W6ClI2 elemental sulphur and triethylphosphine. The cluster skeleton (Figure 5) was found to consist of a regular octahedron of six tungsten atoms coordinated with p3-sulphido ligands on each triangular face and triethylphosphine as each metal vertex. The structure is almost identical to that of the molybdenum analogue. Differences in the electronic spectra and the one-electron- oxidation and reduction potentials were discussed in terms of the electronic levels of the w& framework which may be regarded as the cluster core of the unknown tungsten analogues of the Chevrel phase compounds.Interest in tungsten(v1) I03 M. El Khalifa F. Y. Petillon J.-Y. Saillard and J. Talarmin Inorg. Chem. 1989 28 3849. 104 T. R. Halbert and E. I. Stiefel Znorg. Chem. 1989 28 2501. 105 M. Parantharnan G. Aravarnudan and G. V. Subba Rao Mat. Res. Bull. 1989 24 931. 106 T. Saito A. Yoshikawa T. Yarnagata H. Imoto and K. Unoura Inorg. Chem.. 1989 28 3588. F. J. Berry W Figure 5 Molecular structure of [W,S,( PEtJ6] (Reproduced by permission from Inorg. Chern. 1989 28 3588) tetrahalide oxides and chalcogenides is partially derived from their versatility as starting materials for synthesis but also reflects the curiosity concerning the diverse structural forms which they adopt.It is therefore interesting to note the synthesis of a new polymorph of tungsten(v1) sulphide tetrachloride WSCl, and its structural 0 S Se Te 35 characterization. lo7 The complex (p-ethylenediaminetetraacetato)(p-oxo)(p-sulphido)bis(oxotungstate(v)) has been preparedlog and shown by X-ray crystal- lography to be the first complex containing the W,(O),(p-O)(p-s)unit. New ternary Ln32Nb28Sgg (Ln = La Ce) compounds have been ~ynthesized'~' and the structure of La32Nb28S28 described as a mixed sandwich layered type in which the INbS21 and ILaSl slabs alternate.The origin of metal clustering in transition metal layers MX2 where M is a transition metal and X is chalcogen has been examined' lo by performing tight-binding band electronic structure calculations on CoMo2S4,V3S4 Mo2S3 and Nb2Se3. The energy factors governing the partial irreversibility of lithium intercalation in layered trichalcogenides MX3( M = Ti Zr Hf; X = S Se) and the structural changes in the intercalated species Li,MX3 have been assessed."' A one-step mechanism was proposed for chemical intercalation in which each metal of MX3 is affected by three lithium atoms at a time. The synthesis of a molecule containing a simple unsupported M-S-M' linkage has been described'12 in a report of the preparation and reactivity of the first structurally characterised heterobimetallic complex containing an unsupported bridging sulphur atom."2 The synthesis of the defect thiospinel systems Cul-,[Ti2]S4 by the extraction of copper from Cu[Ti],S4 with iodine at 45 "C has been de~cribed."~ Structural charac- terization of these metallic or semimetallic Pauli paramagnetic materials was achieved by use of X-ray- and neutron-diffraction.The open-circuit voltage of electrochemically lithiated Cu[Ti2]S4 was found to be higher than that of CU~,~~[T~~]S~. The preparation and physico-chemical properties of the new titanium(1v) porphyrin complexes (Por)Ti(Y,) where Y is S or Se and Por is porphyrinate dianion have been reported.' l4 The structure of the (TpTP)Ti( S,) complex where TpTP is tetrakis-p- toly( porphyrin) was solved by single crystal X-ray diffraction.The tantalum subsulphide of composition Ta3Sl, has been prepared115 by a sealed silica tube synthesis at 1300°C. The structure of the compound which is metallic at room temperature was shown to be closely related to that of Ta2S. A new barium tantalum sulphide of composition Ba3Ta2Sg has been prepared' l6 by sulphurization of a mixture of BaC03 and Ta205. Another phase of composition BaTa,S5 was prepared117 from the reaction of CS with a mixture of BaCO and Ta,OS and was found to be metallic and Pauli paramagnetic. Solid state reactions have been used'" to prepare two new chalcogenides of composition I(4Ta2Sll and K3Nb2Sell. The compounds contain the discrete anions Ta,S:i and Nb4Se6, which resemble the 107 F.A. Cotton P. A. Kibala and R. B. W. Sandor Inorg. Chem. 1989 28 2485. I08 S. Ikari Y. Sasaki and T. Ito Inorg. Chem. 1989 28 447. I09 A. Meerschant P. Rabu and J. Rouxel J. Solid State Chem. 1989 78 35. 110 E. Canadell A. LeBeuze M. A. El Khalifa R. Chevrel and M. H. Whangbo J. Am. Chem. Soc. 1989 11 3778. 111 E. Canadell C. Thieffry Y. Mathey and M.-H. Whangbo Inorg. Chem. 1989 28 3043. 112 J. A. Kovacs and R. G. Bergman J. Am. Chem. SOC.,1989 111 1131. 113 A. C. W. P. James J. B. Goodenough N. J. Clayden and P. M. Banks Mat. Res. Bull. 1989 24 143. 114 C. Ratti P. Richard A. Tabard and R. Guilard J. Chem. Soc. Chem. Commun. 1989 49. 115 H. Wada and M. Onoda Mat. Res. Buff.,1989 24 191. 116 M.Onoda and M. Saeki Mat. Res. Bull. 1989 24 625. 117 M. Saeki H. Nozaki and M. Onoda Mar. Rex Bull. 1989 24 851. 'I8 S. Schreiner L. E. Aleandri D. Kang and J. A. Ibers Inorg. Chem. 1989 28 392. F. J. Berry closely related tungsten and molybdenum species which can be prepared by solution methods. The reaction between (Cp*Ta)(SCH2CH2S), where Cp*Ta is pen- tamethylcyclopentadienyltantalum,with Li,S in tetrahydrofuran has been found’ l9 to give the compound [(Cp*Ta(S)3Li2(THF)2]2 which was shown to contain a hexagonal prismatic Ta,Li,S core (Figure 6). The compound [{Pr;P(CHz)3PPr~}TaHCl]2(p-S)(p-H)z has been prepared’” from the Na/Hg reduction of Ta,CI,( SMe,)3 in the presence of 1,3-bis(diisopropy1phosphino)pro-pane and was shown to contain a bridging sulphido ligand.Figure 7(a) shows that the sulphur atom bridges symmetry related tantalum atoms and although only one site occupied by the p-S is shown was found to occupy two locations each with 50% site occupancy. The side view [Figure 7(b)] depicts the likely positions of the bridging and terminal hydrides. Figure 6 Molecular structure of [(C,Me,)Ta(S)3Li2(thf)2]2 (Reproduced by permission from J. Am. Chem. Soc. 1989 111 782) Figure 7 (a) Molecular structure and (b) side view of [{PriP(CH2)3PPr;)TaHCl]2(p-S)(p-H)2 (Reproduced by permission from Inorg. Chem. 1989 28 1613) 119 K. Tatsumi Y. Inoue and A. Nakamura J. Am. Chem. SOC.,1989 111 782. 120 M. D. Fryzuk and D. H. McConville Inorg. Chem. 1989 28 1613. 0,S Se Te The magnetic structure of the compound PrCrOS has been examinedI2' and found to be antiferromagnetic and similar to other compounds of composition LnCrOX2 where Ln is La to Nd and X is S or Se.The metal carbonyls Mo(CO)~ and W(CO)6 have been found', to undergo oxidative decarbonylation in the presence of polysulphide or polyselenide to generate MSi- and MSei- respectively whilst the reaction of Cr(C0)6 with polysulphide solution generates the novel [(C,H5)4P]3[Cr(S2CO),1 complex in which the chromium is located in distorted octahedral sulphur coordination (Figure 8). The insertion of elemental sulphur into the cumulated linear triple bond Crr SesCr in [Cr,(Cp),(CO),Se] where Cp is r]-C5H5 has been found'23 to give [Cr,(Cp),(CO),Se,] [Cr2(Cp)2(CO)4S2]and [Cr2(Cp)2(CO)4S] together with the sulphur selenides S,Se and S,Se,.NMR and TLC studies indicated the transformation to occur via dichalcogen species of the type rcr,(cP),(co),s(se)l and [cr,(cp),(co),s(se>l. Figure 8 Structure of [Cr(S2C0),l3-(Reproducedby permission from Znorg. Chem. 1989 28 2780) Single crystals of the new semiconducting and diamagnetic phase Tl4Re6SI2 have been synthesized by high temperature reactions between TlX rhenium and sul- phur.l2 The anion [Ni,S(SC,H,),]- has been to contain a sulphide ion at the centre of a Ni6 prism capped by two additional nickel atoms in an arrangement involving nine p2-SBu' bridges (Figure 9). The anion is the first pure nickel-sulphur complex with nickel in the unusual mean oxidation state of +1.25.Complexes of the type (C,H4R)Ru(PPh3),EH where E is S or Se have been found to undergo condensation in hot toluene solutions to give compounds of composition [(C5H4R)4R~4E4] which contain the first Ru4E cubanes.'26 The synthesis and structural properties of the first closo and nido clusters of the type [(p-~ymene)~M~S,]'+ and [(p-~ymene),M,S,]~ where M is Ru or 0s have been repor- ted.', An optically active sulphoxide has been produced by using colloidally 121 M. Winterberger V. Tien M. Guittard and J. Dugue. J. Solid State Chem. 1989 79 285. 122 S. C. O'Neal and J. W. Kolis Znorg. Chem. 1989 28 2780. 123 L. Y. Goh J. Chem. SOC. Dalton Trans. 1989 431. 124 G. Huan M. Greaney P. P. Tsai and M. Greenblatt Znorg. Chem. 1989 28 2448.125 T. Kruger B. Krebs and G. Henkel Angew. Chem. Znt. Ed. Engl. 1989 28 61. 126 J. Amarasekera T. B. Rauchfuss and S. R. Wilson J. Chem. SOC.,Chem. Commun. 1989 14. 127 J. R. Lockemeyer T. B. Rauchfuss and A. L. Rheingold J. Am. Chem. Soc. 1989 111 5733. F. J Berry a U Figure 9 Schematic drawing of the Ni8S, framework of the complex anion [Ni,S(SC,H,),]-(Reproduced by permission from Angew. Chem. Znt. Ed. Engl. 1989 28 61) dispersed A-tris (2,2'-bipyridyl)ruthenium( 11) montmorillonite as a photo-sensitizer.I2' Novel dimers of composition [Rh(XB,,H,,){S,C( H)( PPh,)}] where X is Se or Te have been synthesized and shown to contain a unique cis-bis(phos- phonium-betaine) intercluster linkage with each ligand having one sulphur atom bridging both rhodium atoms and the other sulphur atom simply coordinating to a rhodium atom.'29 The first full assignment of the single-crystal Raman spectra between 275 and 1200cm-' recorded from the caesium rhodium alums CsRh(SO,),.12H20 CsRh( Se04)2.12H20 and CsRh(S0,),.12D20 at low tem- peratures has been rep~rted.'~' The crystal structures of [N(C2H,),][Pt{S2C,(CN),),1 and [H20],[NH,],~,[Pt{S2C2(CN)2}2]~2xH,0 have both been shown'31 to contain dimers. The dimer in the former species has a slipped configuration with Pt... S interactions whereas the latter contains the anion in an eclipsed configuration with a Pt over Pt arrangement. The electrical conduction and magnetic properties were related to the structures. The crystal structures of K[ Pd{S,C,(CN),},]~H,O and NH4[ Pd{ S,C,(CN),},].H,O have been described.'32 The former was found to adopt a structure consisting of an equidistant columnar stack of anions whereas the latter compound had anions arranged as dimers in an eclipsed Pd over Pd arrangement.The X-ray crystal structure of CS~.~,[ Pd{S2C2(CN),),].0.5H20 where S,C,(CN);- is 1,2-dicyanoethylene-1,2-dithiolate,has that the [Pd(S,C,(CN),},]-anions are strongly associated as eclipsed dimer pairs. The arrangement of the anion dimers (Figure 10) is unusual and leads to short S...S contacts between dimers in two orthogonal directions. A superstructure was observed at low temperatures and the structural properties of the material were related to its metallic conductivity when subjected to pressure.The interactions in dichloromethane solution of Pt(S,( NEt,) with a number of sulphur- and selenium-containing potentially biden- 128 T. Hikita K. Tamaru A. Yamagishi and T. Iwarnoto Inorg. Chem. 1989 28 2221. 129 Faridoon T. R. Spalding G. Ferguson J. D. Kennedy and X. L. R. Fontaine J. Chem. Soc. Chem. Commun. 1989 906. 130 S. P. Best J. K. Beattie R. S. Armstrong and E. P. Braithwaite J. Chem. Soc Dalton Trans. 1989 1771. 131 P. 1. Clemenson A. E. Underhill M. B. Hursthouse and R. L. Short J. Chem. Soc. Dalton Trans. 1989 61. 132 M. B. Hursthouse R. L. Short P. I. Clemenson and A. E. Underhill J. Chem. Soc. Dalton Trans. 1989 67. 133 M. B. Hursthouse R. L. Short P. 1. Clemenson and A. E. Underhill J. Chem. Soc.Dalton Trans. 1989. 1101. 0,S Se Te Figure 10 View along the b axis of CS~.~~[P~{S~C~(CN)~}~]*O.~H~O (Reproduced by permission from J. Chem. SOC.,Dalton Trans. 1989 1101) tate ligands have been studied'34 by multinuclear (31P 77Se 195Pt) magnetic resonance techniques and compared to the reactions of Pt(S,P{OEt}2)2. A new tetradentate macrocyclic ligand in which two amide and two sulphide units act co-operatively has been found135 to show high selectivity and efficiency for complex formation with platinum(I1) and palladium(I1) over copper(II) nickel( I]) and colbalt(r1). The synthesis of [Pt,(p-S)(p-dppm)( ~'-dppm)~] where dppm is Ph2PCH2PPh2 has been described'36 and its use for the formation of tetranuclear platinum complexes with p4-S ligands has been discussed.A study of the tetrathiafulvalenium salts of planar platinum( 11) palladium(II) and copper( 111) 1,2-dithio-oxalato-S,S' anions has the synthesis chemistry and molecular structures of bis(tetrathiafu1- valenium)bis( 1,2-dithio-oxalato-S,S')palladate(XI) [ttf12[ Pd( S2C202),] and of bis( tetrathiafulvalenium) tetrathiafulvalenebis( 1,2-dithio-oxalato-S S')platinate( II) [ttf13[Pt(S2C202)2]. The oxidation of the Pt2(p-S02)moiety to (p-SO3)has been rep~rted'~'and the crystal structure of [Pt2(p-S03)(p-S02)(CsH12)2)] has been described. The cyclopalladation reactions of several sulphur-containing ligands have been investigated and various examples of sulphur-assisted intramolecular pallada- tion of aryl and alkyl groups have been described."' Zinc sulphide films have been prepared by the conversion of zinc oxide films with hydrogen ~ulphide.'~' The films which contained both the hexagonal and cubic I34 R.Colton and J. Ebner Inorg. Chem. 1989 28 1559. 135 E. Kimura Y. Kurogi S. Wada and M. Shionoya J. Chem. SOC.,Chem. Commun. 1989 781. 136 N. Hadj-Bagheri and R. J. Puddephatt Inorg. Chem. 1989 28 2384. 137 C. Bellitto M. Bonamico V. Fares P. Imperatori and S. Patrizio J. Chem. SOC.,Dalton Trans. 1989,719. 138 D. H. Farrar and R. R. Gukathasan J. Chem. SOC.,Dalton Trans. 1989 557. 139 J. Dupont N. Beydoun and M. Pfeffer J. Chem. SOC.,Dalton Trans. 1989 1715. 140 Y.-M. Gao P. Wu J. Baglio K. Dwight and A. Wold Mar. Rex Bull. 1989 24 1215. 40 E J.Berry forms of zinc sulphide were shown to be uniform and gave a measured band gap of 3.65 eV. A new orthorhombic metastable form of cadmium sulphide CdS has been prepared through solid-gas reactions of CdO with a sulphiding gas mixture at 750°C for 3 hours and slow cooling under nitrogen atmo~phere.'~~ Controlled methods for the formation of cadmium polysulphide complexes from cadmium sulphide sodium sulphide and sulphur in DMF have been described.', '13Cd NMR was used to identify the existence of the series of monocadmium complexes [Cd(SX),l2- which undergo slow exchange (< 10 s-') at ambient temperature. The principal Cd NMR resonances were assigned to [Cd(S,),]'- [Cd(S,)(S6)I2- and [Cd(S6),I2- with [Cd(S,)(S,)]'- also being postulated. The crystal structures of (Ph,P),[Cd( s6),] and (Ph4P),[{(S6)056( S7)044}Cd( S6)] demonstrated the variability of cadmapolysulphane ring sizes and conformations which can be obtained within this sytem.The direct synthesis of cadmium sulphide within the pore structure of zeolites has been shown'43 to lead to a novel supercluster with a structural geometry superimposed by the host framework. Detailed X-ray powder diffraction and EXAFS analysis together with optical absorption data revealed discrete (CdS 0) cubes located within the small sodalite units of the structure which begin to interconnect as the loading density within the zeolite rises. The discrete cube building blocks were shown to consist of interlocking tetrahedra of cadmium and sulphur. At higher loadings the cubes begin to occupy adjacent sodalite units where the Cd atoms point toward each other through the double six-rings linking the sodalite moieties with a Cd-Cd distance of ca.6 A.The development of this three-dimensional interconnection is accompanied by corresponding changes in optical properties indicative of a progression towards a semiconductor supercluster with behaviour intermediate between that of the discrete CdS cubes and the bulk semiconductor. These types of semiconductor superclusters represent a novel class of materials where the three dimensional structure and electronic properties can be controlled by using different zeolites as the template. The unique stability of the semiconductor clusters inside the sodalite units derives from the coordination of cadmium atoms with the framework oxygen atoms of the double six-ring windows.The stability of the supercluster comes from the interaction between clusters in the adjacent sodalite units. Direct evidence for adduct formation between butenes and etched single crystal n-CdS and n-CdSe surfaces have been obtained from photoluminescence meas~rements.'~~ from three Infrared transmission spectra have been meas~red'~' kinds of spinel-type mixed systems Cd,Znl-xCr2Se4(1-,lS4Y where x = 1 y = 1 and x = y = 0.2 from 50-900 cm-' and at 300 and 16 K. Solid solutions throughout the whole composition range in the systems Y202S- La,O,S Y202S-Gd202S and Gd202S-La202S have been ~btained.',~ The electrical conductivity of the solid solution Eu~~Eu:',Li,-,S has been determined', by the 141 M.Kizilyalli M. Bilgin and A. Usuanmaz J. Solid Stare Chem. 1989 80 75. 142 R. M. Herath Banda I. G. Dance T. D. Bailey D. C. Craig and M. L. Scudder Inorg. Chem. 1989 28 1862. 143 N. Herron Y. Wang M. M. Eddy G. D. Stucky D. E. Cox K. Moller and T. Bein J. Am. Chem. SOC.,1989 111 530. 144 G. J. Meyer L. K. Leung J. C. Yu G. C. Lisensky and A. B. Ellis J. Am. Chem. SOC.,1989 111 5146. 145 K. Wakamura J. Solid State Chem. 1989 78 197. 146 C. R. Ronda H. Mulder and D. B. M. Klaassen J. Solid Sture Chem. 1989 80 299. I47 M. Palazzi and E. Bretey Mar. Res. Bull. 1989 24 695. 0 S Se Te complex impedance method and shown to be of electronic origin arising from electron transfer between Eu2+ and Eu3+.4 Selenium The anions in compounds of composition [(C2Hs)4N]2{ Se"Se'VBr8] have [(nC3H8)4N]2[Se~'Se'vBr,ol,and [(C6H5)4P]2[Se:'Se'VBr~2].cH2c12 been to contain distinct Se" and Se'" centres (Figure 11). The Se" centres in Figure 11 Sfrucrure of the [Se$e'"Br,,] anion (Reproduced by permission from Angew. Chem. Int. Ed. Engl 1989 28 187) these novel mixed valence compounds are coordinated in a square-planar fashion whilst the Se'" centres are octahedrally coordinated. The Se"-Se" distance of 3.335 is notably short. Compounds of the type (SkNSeNSk),(AsF,), where n is 1 or 2 which contain the first stable binary selenium-nitrogen species have been prepared by the reaction of stoicheiometric quantities of %4(ASF& (n = 2) or AsF (n = 1 and 2) with Se,N in liquid sulphur di0~ide.l~~ ESR spectroscopy showed that (deNSeNSk)2(AsF,) gives the indefinitely stable 7.n radical SeNSeNSe+' in solution whilst Raman and infrared spectroscopy showed that SeNSeNde( AsF,) gives the 67r SLNSeNSe2+ cation.The structures of the solid species were character- ized by X-ray crystallography. The reaction of Se4N with [PtCI2( PMe2Ph)12 in CHC13 has been found'50 to give Pt(Se3N)C1(PMe2PH) which is the first example of a metal selenium-nitrogen complex. The ccjmplex contains the bidentate selenium- bound Se,N- ligand and from X-ray crystallography was shown to be square planar with a bidentate Se,N- ligand coordinated through two selenium atoms. A more substantial interest in selenium-nitrogen chemistry might be a consequence of the synthesis'" of platinum complexes of the anions Se2Ni- and Se2N2H- in liquid ammonia which avoids the necessity to work with isolated unstable Se4N4.The method involves the addition of a complex such as cis-[PtC1,(Ph,PCH2PPh2)] to i? reaction solution of SeC1 in liquid ammonia and allowing the reaction mixture to 148 B. Krebs E. Luhrs F.-P. Ahlers Angew. Chem. Inr. Ed. Engl. 1989 28 187. I49 E. G. Awere J. Passmore P. S. White and T. Klapotke J. Chem. SOC.,Chem. Commun. 1989 1415. 150 P. F. Kelly A. M. Z. Slawin D. J. Williams and J. D. Woollins J. Chem. Soc. Chem. Commun. 1989 408. 151 P. F. Kelly I. P. Parkin A. M. Z. Slawin D. J. Williams and J. D. Woolins Angew. Chem. Inf. Ed. Eng. 1989 28 1047.42 F. J. Berry warm to room temperature to give selenium-nitrogen metallacycles such as [Pt(Se2N2)( Ph2PCH2CH2PPh2)] which can be protonated with HBF,. The X-ray structure of the related complex [Pt(Se2N2H)( PMe,Ph),]Cl showed the presence of essentially planar P2PtSe2N units stacked in a parallel and overlapping fashion. The reaction of (NSC1)3 with aluminium trichloride at 50 "C in the absence of solvent has been shown to produce [NS]+[AlCl,]- which reacts with alkylselenium halides to give [N2S2SeCl]+[A1C1,]- in which the cation is composed of a five-membered ring with chlorine attached ta selenium.'s2 The high-resolution 77Se NMR spectra of potassium and rubidium hydrogen selenities have been recorded using the cross-polarization method and the chemical shift tensors of selenium nuclei found to be typical for HSeO; c~nfiguration."~ The structure of the compound (Lao)@,,& 82 has been shown'54 to consist of alternating (Lao) and (Gao94Se2,41) layers parallel to the (001) plane.Studies of the soluble polychalcogenide chemistry of indium have been developed with the synthesis and characterization of [In,Se,,14- representing the first reported indium p~lyselenide.'~~ Single crystals of the new compound Pr,lnSe6 have been obtained'56 by direct reaction between Pr Se and ln,Se powders at 950 "C and were subjected to structural characterization by X-ray crystallography. The localized structural differences between crystalline and amorphous ger- manium diselenide GeSe2 have been examined by both Ge and Se K edge EXAFS and discussed in terms of clustering proces~es.'~~ The EXAFS recorded from ger- manium selenide glasses showed the selenium environment to vary strongly between GeSe3 and GeSe,,,.and between bulk phases and thin films as a result of selenium clustering in selenium-rich compositions.'s8 An X-ray crystallographic and dynamic 'H NMR study of 2,2,5,5-tetramethyl-1,3-diselena-2-germacyclohexane has shown's9 the compound to exist in a symmetrical 2,Stwist-boat conformation both in the solid state and in solution. The ,'P and 77Se NMR spectra of some sulphur- or arsenic-substituted derivatives of tetraphosphorus triselenide have been recorded16' and the chemical shifts and coupling constants fitted to molecular parameters for cage compounds containing a phosphorus-selenium-phosphorous linkage.16' Homonuclear dipolar coupling information derived from solid state NMR spectra have been used to test structural models of atomic distribution and local order in the phosphorus-selenium systern.l6' The reduction of As4Se by potassium in ethylenediamine in the presence of tetraphenylphosphonium bromide has been found'62 to form the compound P(C6H5)4*AS7Se4.The X-ray crystal structure showed the anion to contain arsenic 152 A.Apblett T. Chivers and J. F. Fait J. Chem. SOC.,Chem. Commun. 1989 1596. 153 I. S. Vinogradova A. A. Sukhovskii and F. F. Khizbullin J. Solid State Chem. 1989 78 209. 154 S. Benazeth P. Larnelle and M. Guittard J. Solid State Chem. 1989 78 148.155 M. G. Kanatzidis and S. Dhingra Inorg. Chem. 1989 28 2024. 156 L. E. Aleandri and J. A. Ibers J. Solid State Chem. 1989 79 107. 157 C. Peyroutou S. Peytavin M. Ribes and H. Dexpert J. Solid State Chem. 1989 82 70. 158 C. Peyroutou S. Peytou M. Ribes and H. Dexpert J. Solid State Chem. 1989,82 78. 159 S. Tomoda M. Shimoda M. Sanami Y.Takeuchi and Y. Litoka J. Chem. SOC.,Chem. Commun. 1989 1304. B. W. Tattershall R. Blachnik and M. P. Baldus J. Chem. SOC., 160 Dalton Trans. 1989 977. 161 R. Lathrop and H. Eckert J. Am. Chem. SOC.,1989 111 3536. V. Angilella H. Mercier and C. Belin J. Chem. SOC.,Chem. Commun. 1989 1654. 162 0 S Se Te Figure 12 Two views of the geometry of the As,Se anion in the compound P(C,H,),.As,Se (Keproduced by permission from J.Chem. SOC. Chem. Commun. 1989 1654) and selenium atoms in higher coordination than that which is generally observed in cage or cyclic anions involving arsenic and chalcogenide species. (Figure 12). The coordination of bismuth in dilute alloys of the noncrystalline Se,,,-,Bi system has been rein~estigated.',~ The synthesis of highly crystalline selenium analogues of sulphur-rich sulphur- iodine compounds Of the type Se6I,(ASF,)2*?SO, (Se61); nASF6 and (Se6I),*SbF6 has been des~ribed.'~~ The %,I:+ cation in Se612(AsF,)2-2S02 contains a six-membered ring of chair conformation with the two iodine atoms joined to the ring in the 1,4-positions with an endo conformation. Four intracationic I-Se contacts gives the cation a distorted cubelike shape (Figure 13).The geometry of the Se612 I Figure 13 The s~,I:+ cation in S~,I,(ASF,),.SO (Reproduced by permission from Inorg. Chem. 1989 28 3320) unit in the (Se61+), cations in isostructural (Se61);nMF6 (M = As Sb) is similar to that in Se,If' but the iodine atoms bridge Se rings giving rise to (Se61+), strands. (Figure 14). A short synthesis of tetraformyltetraselenafulvalene (TFTSeF) has been des- ~ribed.',~Its use as an efficient precursor of polyfunctionalized tetrasubstituted tetraselenafulvalene such as a tetravinylic derivative via a Wittig reaction and I63 A. Munoz F. L. Cumbrera and R. Marquez J. Solid State Chem. 1989 80 189. 164 W. A. Shantha Nandana J. Passmore P. S. White and C.-M.Wong rnorg. Chem. 1989 28 3320. 165 M. SallC A. Gorgues J.-M. Fabre K. Bechgaard M. Jubault and F. Texier J. Chem. SOC.,Chem. Commun. 1989 1520. F. J. Berry Selenium Iodine Figure 14 The (Se,I+),polymericchain in (Se,I);nMF (M = As Sb) illustrating the interaction of the bridging iodine atom with the adjacent Se rings (Reproduced by permission from Inorg. Chem. 1989 28 3320) tetrakis( hydroxymethy1)-TSeF by a simple NaBH reduction was demonstrated. The growth by anodic electrocrystallization of single crystals of the isomorphous electri- cally-conducting chloride and bromide of 1,4,5,8-tetraselenonaphthalene(TSeN) has been described.'66 The chloride was shown to be composed of dimers of parallel TeSeN cation radicals as opposed to infinite chains and to exhibit Curie law magnetic behaviour.The reaction of Cr(C0)6 with soluble polyselenide in DMF has been shown to result in complete oxidative decarbonylation and to give an unidentified mixture of higher chromium selenides.'22 The insertion of elemental sulphur into the linear triple bond CrESeGCr of [Cr,(~p),(C0)~Se] where cp is r]-C5H5 has resulted in the of [C~(cp),(C0)~Se,] together with other compounds including the sulphur selenides S,Se and S6Se2. X-ray diffraction and DTA studies of the pseudo- binary system Cr,VSe (0< x < 1) in the temperature range 300-1100°C have shown the existence of six phase^.'^' The thermal motion of silver in the two-dimensional silver ion conductor AgCrSez has been studied as a function of temperature by single-crystal X-ray diffraction.'68 The structural parameters superconducting critical temperatures and magnetic 166 L.A. Acampora B. S. Elman D. J. Sandman S. Jansen M. T. Jones R. D. Rotaiczak and B. M. Foxman Znorg. Chem. 1989 28 1579. 167 A. Hayashi Y. Ueda and K. Kosuge Mat. Res. Bull. 1989 24 825. 168 A. Van der Lee and G. A. Wiegers J. Solid Stare Chem. 1989 82 216. 0 S Se Te susceptibilities of the solid solution AgMo,S,- Sex have been reported and discussed in terms of structural and electronic instabilities in the AgMo,Se ~ystern.'~' The synthesis structure and properties of indium intercalation compounds of tungsten diselenide of composition Ln,WSe (0< x < 1) have been de~cribed.'~' The materials were found to exhibit n-type semiconductivity.The synthesis and structural properties of mixed metal selenide anions of composition Ni( Se,)( WSe,)'- and M(WSe,);- where M is Ni or Pd have been rep~rted.'~' The reaction of dimethyl acetylenedicarboxylate with WSei- and W,Se:; has been shown to give the new soluble anions of composition W(Se2C2(COOCH3),)~- and W2Se2( Se2C2(COOCH3)2)i- re~pective1y.l~' The origin of metal clustering in transi- tion metal layers has been examined"' by performing tight-binding band electronic structure calculations on a variety of metal sulphides and Nb2Se3. The electronic structures of butterfly complexes of the type P2M2(C0),E2 where M is Cr Mo or W and E is S or Se have been as~essed.''~ The new phase Tl,Re,Se, has been synthesized as single crystals from the high temperature reaction of TlSe selenium and ~henium''~ and shown to consist of Re6Se8 cluster units interconnected three-dimensionally by four selenium and two Se bridges (Figure 15).The compound is semiconducting and diamagnetic. W5) W5) ( Figure 15 Structural unit of Tl,Re,Se, (Reproduced by permission from Inorg. Chem. 1989 28 2448) The synthesis and structural properties of metal rich nickel cluster compounds with selenium ligands having novel structures have been de~cribed.'~~ The phase diagram of the (Fe,Ti,-,),Se system has been determined and the magnetic proper- ties e~arnined.'~ The 'H NMR and electron transfer properties of oxidized and reduced [Fe,Se,] derivatives of CZostridiurn vinosurn high-potential iron protein have been in~estigated.'~' 169 D.C. Johnson R. S. McLean and W. R. McKinnon J. Solid State Chem. 1989 82 35. 170 S. K. Sriovastava Mat. Res. Bull. 1989 24 1031. 171 M. A. Ansari C.-N. Chau C. H. Mahler and J. A. Ibers Znorg. Chem. 1989 28 650. 172 M. A. Ansari C. H. Mahler and J. A. Ibers Znorg. Chem. 1989 28 2669. 173 D. Fenske and A. Hollnagel Angew. Chem. Znt. Ed. Engl. 1989 28 1390. 174 A. Hayashi T. Kishi Y. Ueda and K. Kosuge Mat. Res. Bull. 1989 24 701. 175 M. Sola J. A. Cowan and H. B. Gray J. Am. Chem. Soc.; 1989 111 6627. F. J. Berry The synthesis of [ (Ph,P)AgSe,] and its characterization as the first silver poly- ~elenide'~~ is notable since it features an unprecedented low-dimensional polymer structure.The single-crystal X-ray diffraction analysis showed the material to be composed of non interacting Ph,P+ cations and [Ag( Se,)] :-macroanions which form infinite one-dimensional chains running parallel to the monoclinic b-axis (Figure 16). The basic repeating unit is a five-membered AgSe ring containing the chelating SeT2 ligand such that each chain can be envisaged as a corrugated ribbon. The structure is unique and has no parallel in chalcogenide chemistry. The pre- liminary examination of charge transport and optical properties along the needle axis indicated wide bandgap/narrow bandwidth semiconducting behaviour. Figure 16 Two views of a [Ag(Se4)]i-chain four unit cells long. Black dots represent silver atoms (Reproducedby permission from J.Am. Chem. SOC. 1989 111 760) Small ensembles of CdSe have been synthesized within the cage system of zeolite Y via ion exchange with cadmium(11) and subsequent treatment with H2Se.177 The cluster sizes and geometrical arrangements were determined by comprehensive analysis of Cd- and Se-edge EXAFS data and synchrotron X-ray powder diffraction data together with model calculations. The CdSe molecular clusters were stabilized at ambient conditions through strong interactions with the zeolite host. Se 0-bridged cadmium dimers and Cd404 cubes were identified in the sodalite unit. Cadmium ions present in 12-ring windows were found to be coordinated to one selenium and additional oxygen atoms. Small amounts of selenium helical chains and CdSe clusters were also detected.The photoluminescent properties of cadmium selenide in the presence of butenes have been reported.Ia The vibrational spectra of the spinel-type systems Cd,Zn,-xCr2Se4(l-,~S4 have been de~cribed.',~ The preparation of thin films of mercury selenide on a glass substrate has been achieved using mercury formamide and sodium selen~sulphate.'~~ The adherence and uniformity of the films was improved by addition of polyvinyl pyrollidone and the amorphous films found to be p-type semiconductors with an energy gap of 1.42 eV. 176 M. G. Kanatzidis and S.-P. Huang J. Am. Chem. SOC.,1989 111 760. I71 K. Moller M. M. Eddy G. D. Stucky N. Herron and T. Bein J. Am. Chem. SOC.,1989 111 2564. 178 P. Pramanik and S.Bhattacharya Mat. Res. Bull, 1989 24 945. 0,S Se Te 47 Vapour phase transport techniques using iodine have been to prepare single crystals of CeSel,9 and PrSe,, . An efficient one-pot synthetic procedure for the preparation of the electron donor bis( ethylenedise1eno)tretrathiafulvalenefrom tetrathiafulvalene has been described.'" 5 Tellurium The mixed oxides M2(GeTe)0 (M = K Rb Cs) have been prepared by a solid state reaction between Te(OH) ,GeO ,and MN03 and found to adopt a pyrochlore- type structure.'" The formation and thermal behaviour of glasses in the As-Ge-Te system has been investigated.'" Semimagnetic semiconductors with rare-earth mag- netic ions of the type Pb,-,Gd,Te have been prepared as single- and p~ly-crystals.'~~ The solid solution range was found to be limited to x < 0.1 and the gadolinium-lead ion substitution processes were discussed in terms of the NaC1-type structure.The EPR linewidths as a function of orientation temperature and composition were associated with relaxation mechanisms. Tellurium-125 NMR and electrochemical data recorded at mercury and platinum electrodes have shown'84 that the tellurium( IV) dithiocarbamate (dtc) complexes Te(dtc) are unstable in solution with respect to an internal redox reaction producing the tellurium(I1) complex Te(dtc) and thiuram disulphide with a rate which is solvent dependent. The structure of NaTeF has been determined by single crystal X-ray diffra~tion"~ and found to contain $-octahedral TeF; anions. The existence of several new polymorphs of KTeF and RbTeF have been identified and their structural proper- ties examined.'86 The compounds Fe(TPP)(OTeF,) and Fe(OEP)(OTeF,) together with their "0 analogues have been prepared and characterized by magnetic suscepti- bility measurements 'H and 19F NMR UV-vis and infrared spectroscopy and cyclic v~ltammetry.'~~ The results showed the complexes to contain high spin iron(1ri) and the relative ligand field strength of the OTeF anion to follow the order C1-> OTeF,-> ClO,.The crystal structure of Fe(TPA)(OTeF,)(THF) was described. A new compound of composition Tb2Te4O1 ,has been synthesized by the solid state reaction of TeOz and Tb,O at 700-800 "C in air.'** The material changed on prolonged treatment at 800 "C to isostructural Tb2Te4-p011-zy (y < 0.25) and under- went reaction with yttrium to form solutions of the type (Y1-xTbx)2Te4011 (0.01 < x < 1.0).The preparation and properties of the compounds AgTiZrTe and Ag2TiZrTe4 have been rep~rted"~ and shown to adopt similar structures to that of TiZrTe with 179 P. Plambeck-Fischer W. Abriel and W. Urland J. Solid State Chem. 1989 78 164. 1an A. M. Kini B. D. Gates M. A. Beno and J. M. Williams J. Chem. Soc. Chem. Commun. 1989 169. I81 A. Amarilla M. L. Veiga C. Pico M. Gaitan and A. Jerez Inorg. Chem. 1989 28 1701. 182 R. Ollitrault-Fichet H. W. Shu J. Rivet and J. Flahaut Mat. Res. Bull. 1989 24 351. 183 G. Brun J. F. Dumas A. Bruno and J. C. Tedenac J. Solid Stare Cfiem.,1989 81 129.184 A. M. Bonds D. Dakternieks R. Di Giacomo and A. F. Hollenkamp Inorg. Chem. 1989 28 1510. 185 A. du Bois and W. Abriel Mat. Res. Bull. 1989 24 633. 186 J.-P. Bastide P. Germain J.-M. Lttofft R. El Mail and N. Ba Chauh Mat. Res. Bull. 1989 24 293. 1x7 P. J. Kellett M. J. Pawlik L. F. Taylor R. G. Thompson M. A. Levstik 0. P. Anderson and S. H. Straws Inorg. Chem. 1989 28 440. 188 T. Endo A. Shibuya T. Sato and M. Shimada J. Solid State Chem. 1989 78 237. 189 Z. Cybulski and A. Feltz Z. Anorg. Allg. Chem. 1989 569 145. 48 E J. Berry an ordered array of titanium and zirconium atoms at the octahedral sites of the Cd12 type lattice and with Ag+ ions in the interlayer regions. The titanium(1v)-zirconium( ~v) telluride TiZrTe has attracted other attention in connection with potential battery application^'^^ in a study which confirmed an ordered structure and showed the material to have a lower ability for the intercalation of lithium than TiTe and ZrTe .The heat capacities and derived thermophysical properties of isostructural ZrTe and Hffe have been reported."' The compounds Li2TiTe06 and Li2SnTe0 have been s-nthesized and described in terms of the LiSb03 structure with Ti-Te ordering.'92 The oxides A(Tio.,Tel.,)06(A= K Rb Cs Ti) have been obtained as polycrystalline powders and shown to adopt defect cubic pyrochlore-type structure^.'^^ The new layered ternary chalcogenides of composition Ta3Pd3Te14 and TaNiTe have been prepared by high temperature reactions of the elements and shown by single crystal X-ray diffraction techniques to adopt layer structure^.'^^ Electrical conductivity measurements showed both compounds to be metallic.New routes for the synthesis of the compounds OS~(CO)~(~~-T~)~ and Ru3(C0)J p3-Te)2 have been des~ribed'~~ together with details of the synthesis and characterization of the new trimetallic cluster Fe20s3(CO),,( p4-Te)(p3-Te). Silver tellurite Ag2Te03 has been prepared from an aqueous solution and also by oxidation of Ag2Te in air.'96 Cadmium telluride thin films have been grown with a zinc blend structure on glass and tin oxide coated glass and with a wurtzite structure on psi and mica.19' The salts [(p-TePh) (HgPR~)3(Hg)](C104)2 (R = Ph 4-C,H4Me 4-C6H4C1) have been prepared19' and characterized by 3' P 12,Te and 199 Hg NMR spectroscopy.The compounds were shown to be of adomantanoid structure with novel tellurolate bridging. A new uranium tritelluride P-UTe, has been ~ynthesized'~~ and shown to crystallize with the NdTe3-type structure. 190 Z. Cybulski A. Feltz and M. Andratschte Mat. Rex Bull. 1989 24 157. 191 R. Shaviv E. F. Westrum H. Fjellvag and A. Kjekshus J. Solid State Chem. 1989 81 103. 192 J. Choisnet A. Rulmont and P. Tarte J. Solid State Chem. 1989 82 272. 193 A. Castro I. Rasines and X. M. Turrillas J. Solid State Chem. 1989 80 227. 194 E. W. Liimatta and J. A. Ibers J. Solid State Chem. 1989 78 7. 195 P. Mathur I. J. Mavunkal and V. Rugmini Inorg. Chem. 1989 28 3616. 196 S.R. Bharadwaj and G. Chattopadhyay J. Solid State Chem. 1989 80 256. 197 G. K. Padam and G. L. Malhotra Mat. Res. Bull. 1989 24 595. 198 P. A. W. Dean V. Manivannan and J. J. Vittal Inorg. Chem. 1989 28 2360. 199 H. Noel and J. C. Levet J. Solid State Chem. 1989 79,28.