0,S Se Te By F. J. BERRY Department of Chemistry University of Birmingham P.0. Box 363 Birmingham B 15277 1 Introduction Several studies of similar compounds differing in the nature of the Group VI element which illustrate the influence of different chalcogen atoms on chemical and physical properties have been reported. For example a study' of the effect of the chalcogen atom on the magnetic and electrical prqperties of the hexagonal plutonium oxide chalcogenides of composition PuzOzX (X = 0 S or Se) has shed light on the structural and bonding properties of these materials. Other investigations have considered binary compounds differing in the nature of the chalcogen atom and have focused attention on the common structural properties of the solids. For example the indium(1Ir) chalcogenide semiconductors of composition In-2,0,X3 (X = S Se or Te) have been studied' by single crystal X-ray diffraction and found to possess similar structural features which interestingly involve the accommodation of some indium(1).Solid-state vibrational- and 35Cl nuclear quadrupole resonance-spectroscopic studies3 of some trichlorochalcogen tetrachloroaurates of the type [XC13][AuC14] (X = S Se or Te) are illustrative of other approaches to a series of compounds differing in the nature of the Group VI element. Analysis of spectra from the isomorphous [SCI3][AuCI4] and [SeCl,][AuCl,] compounds indicated the AuCI,- ion to be considerably distorted from D4,,symmetry. The X-ray powder diffraction patterns showed that [TeCI,][AuCI,] adopted a different structure with the n.q.r.and vibrational spectra indicating less distortion of the AuC1,- ion. The origins of the distortions in these compounds were considered in terms of secondary bonding interactions. It is also interesting to note the reaction of WC1,X (X = 0 S or Se) with triphenylphosphine which has been shown4 to lead to abstraction of the chalcogen atom the reduction of tungsten(v1) to tungsten(Iv) and the formation of WCI42PPh3. 2 Oxygen The first observation5 of a chemisorbed dioxygen species at the surface of a pure single crystal of silver at room temperature and low pressure is interesting because ' J. M. Costantini D. Damien C. H. de Novion A. Blake A. Cousson H. Abazli and M. Pages J. Solid State Chem.1983 47 210 ' C. Svensson and J. Albertsson J. Solid Slate Chem. 1983 46 46. A. Finch P. N. Gates T. H. Page and K. B. Dillon J. Chem. SOC.,Dalton Trans. 1983 1837. M. G. B. Drew E. M. Page and D. A. Rice J. Chem. Soc. Dalton Trans. 1983 61. R. B. Grant and R. M. Lambert J. Chem. SOC.,Chem. Comrnun. 1983 58. 117 118 F. J. Berry of the importance of silver as a catalyst for the heterogeneous selective oxidation of ethylene to ethylene oxide. The concentration of the adsorbed species was found to be relatively insensitive to surface structure and shown to be some 800-times higher than that inferred from e.s.r. studies of powders. Given the doubt which has previously been associated with the nature of the epoxidating species during the silver-catalysed heterogeneous oxidation of ethylene it is also interesting to record the results of a subsequent study, which showed that the stable dioxygen species chemisorbed on the clean silver crystal surface had no role in the epoxidation reaction and that chemisorbed atomic oxygen and the presence of subsurface oxygen were more likely to be necessary for the catalytic epoxidation of ethylene by silver.The historical interest in the aqueous chemistry of the superoxide radical anion has many origins including its role in biological processes and it is therefore pertinent to record a new and convenient route' to the formation of the superoxide ion in aqueous solution. It is also interesting to note the first reported* example of oxygen atom transfer by a p-0x0-Fe"' oligomer during the oxidation of triphenylphosphine by p-0x0-bis[phthalocyaninatoiron( III)] and the thermo-dynamic studies' of the addition of molecular oxygen to cobalt(I1) complexes in the cobalt(r1)-ethylenediamine-oxygen system in aqueous solution at 25 "C.3 Sulphur A valuable review has appeared" of thio- and seleno-compounds of main-group elements which illustrates how during the last decade modern preparative tech- niques and methods of structural investigation have led to the formation of novel and often unexpected oligomeric and polymeric compounds containing both sulphur and a main-group element. The review draws attention to notable features of bonding structure and reactivities of these types of compounds and describes new develop- ments in the properties and uses of materials such as the boron sulphides and ion-conducting air-stable thioborates ;the molecular polynuclear thio- and seleno- anions of Ga In Si Ge and Sn; the application of new polynuclear sulphide- and selenide-halides of Si and Ge as reagents for inorganic and organic reactions; the synthesis of argyrodite (Ag,GeS,)-like phases with remarkable solid-state properties ; and the characterization of S-H .S type hydrogen bridges which are relevant to an improved understanding of certain interactions in sulphur-containing bio- molecules. Several of these topics have shown themselves to be central themes in the current interest in sulphur-containing compounds. For example the B,S 16 macrocycle (1) has continued to provoke interest especially in respect of its isostruc- tural although not isoelectronic relationship with porphine (2) (Figure 1).Although no complexes have been reported for B8S,6,porphyrins are known to form a wide variety of complexes with both transition metals and simple metal ions. It is therefore interesting to note the recent usell of extended Huckel calculations to compare the valence electronic structures of B,S, and porphine and their Cu2+ complexes and R. B. Grant and R. M. Lambert J. Chem. SOC.,Chem. Commun. 1983 662. ' M. S. McDowell A. Bakac and J. H. Espenson Inorg. Chem. 1983 22 847. C. Ercolani M. Gardini G. Pennesi and G. Rossi J. Chem. SOC.,Chem. Commun. 1983 549. S. Cabani N. Ceccanti and G. Conti J. Chem. SOC.,Dalton Trans. 1983 1247.I" B. Krebs Angew. Chem. Inr. Ed. Engl. 1983 22 113. I' B. M. Gimarc and J. K. Zhu. Inorg Chem.. 1983 22 479. 0,S Se Te 119 S/ \ S (1) (2) Figure 1 Schematic representation of the B,S, macrocycle (1) and porphine (2) (Reproduced by permission from Inorg. Chem. 1983 22 479) which have indicated that the stability of the B8S,6and porphine complexes are comparable. Compounds containing sulphur and other main-group elements have also received attention. Amongst these the sulphur-nitrogen compounds have continued to attract significant interest. For example the synthesis of the quasi-one-dimensional polymer poly(su1phur nitride) with metallic properties has been achievedI2 electrochemically in liquid sulphur dioxide from cyclopentazathienium chloride S,NSCI which itself was prepared by a new method from S5N,FeC14 and CsF.The structure of the six-membered ring of tetrasulphur dinitride S4N2,has been predi~ted'~ by extended Huckel calculations to adopt a half-chair conformation and to be consistent with the X-ray crystallographic analysis. The structures of other six-membered ring-type species such as SqN:+ S4N;- S3N3-,S3N3+,S6 and S,'+ have also been briefly considered14 and the synthesis of several new five- and six-membered saturated heterocycles containing sulphur-nitrogen bonds reported. l4 An interesting structural study of the silver( I) complex tetrakis(tetrasu1phur tetranitrogen dioxide)silver hexafluoroarsenate(v) [Ag(S4N402)4]+[A~F]-,has shown" the silver atoms to lie below a square of four nitrogen atoms with the bisdisphenoidal (triangulated dodecahedral) co-ordination of silver being completed by two intramolecular Ag-0 contacts and intermolecular Ag-N and Ag-0 interactions.The structure shows the tetrasulphur tetranitrogen dioxide ligands to be approximately planar (except for the SOzunits) with only the nitrogen and oxygen atoms attached to S"' interacting with the silver atom and thereby causing minimum disruption to the delocalized bonding in the rest of the ring (Figure 2). The reactions of tetrasulphur tetranitride have also received attention. For example tetrasulphur tetranitride has been found" to react with excess VCI in I' A. J. Banister 2. V. Hauptman and A. G. Kendrick J. Chem. Soc. Dalton Trans. 1983 1016.l3 J. K. Zhu and B. M. Gimarc Inorg. Chem. 1983 22 1996. l4 A. H. Cowley S. K. Mehrotra and H. W. Roesky Inorg. Chem. 1983 22 2095. l5 H. W. Roesky M. Thomas H. G. Schmidt W. Clegg M. Noltemeyer and G. M. Sheldrick J. Chem. SOC.,Dalton Trans. 1983 405. l6 H. W. Roesky J. Anhaus H. C. Schmidt C. M. Sheldrick and M. Noltemeyer J. Chem. SOC.,Dalton Tram. 1983 1207. 120 F. J. Berry Figure 2 The structure of the [Ag(S,N402)4]+ cation showing 50% thermal ellipsoids and the atomic numbering scheme (Reproduced from J. Chem. SOC., Dalton Trans. 1983 405) CH2C12 to form a mixture of VC12(S2N3) and S2N2VCI4 whereas the reaction with excess TiCI4 gives only S4N4TiCI,. The crystal structure of VCI2(S2N3) was found to consist of chlorine-bridged dimers linked by additional weak V- N interactions to form polymeric chains.The six-membered VNSNSN ring was shown to be effectively planar. In another study,17 31P n.m.r. was used to monitor the reactions of tetrasulphur tetranitride with tetraphenyl- and tetramethyl-diphosphine and diphenylphosphine in toluene under reflux. In addition to the six-membered R2PS2N3 ring which has been reported previously and the cyclophosphazenes (R2PN)3,4 two structural isomers of the eight-membered ring R,P2S2N4 were formed. The crystal structure of 1,5-Ph2P( NSN)2PPh2 was found to consist of a folded eight-membered ring with a cross-ring S-S contact. The 1 ,3-(Ph2PNPPh2)S2N3 compound also contained an eight-membered ring with phosphorus atoms in the 1,3-positions.The NSNSN unit was shown to be essentially planar with the phosphorus atoms being ” N. Burford T. Chivers. and J. F. Richardson. Inorg. Chem. 1983 22. 1482. 0,S Se Te 121 out and on opposite sides of the plane. The electronic structure of 1,3-(Ph2PNPPh2)S2N3was compared with that of Ph2PS2N3 using the HMO approach and the strong visible absorption band at ca. 460 nm tentatively assigned to the HOMO (T*)-+ LUMO (T*)transition of a 10 n-electron manifold. Compounds containing sulphur phosphorus and nitrogen have been the subject of other investigations. For example the reaction of (PhzPN),NSC1 with KI in acetonitrile reportedly produces*8 (Ph2PN)2NSI which has been shown by X-ray crystallography to be an inorganic heterocycle composed of a six-membered P2SN3 ring with an exocyclic sulphur-iodine bond.The structure (Figure 3) shows the five-atom NPNPN unit to be planar to within 0.05 % and the sulphur atom to lie about 0.29 8,out of this plane. The conformation and the endocyclic bond lengths and bond angles of the six-membered P2SN3 ring are similar to those found in the corresponding chloride (Ph,PN),NSCI. The exocyclic sulphur-iodine bond [S-I 2.713(3) A] which is said to have significant ionic character is an interesting feature of the structure. The compound was found to decompose at ca. 150 "C to give Ph8P,N6S which is a spirocyclic compound in which two almost planar six-membered P2SN3 rings are fused at a common approximately tetrahedrally co-ordinated sulphur atom (Figure 4).Each of the six-membered rings is formally associated with six n-electrons (assuming sulphur contributes one n-electron to each ring) and this may account for the high thermal stability of (Ph2PN),N2S which is the final product of many thermal transformations involving PNS heterocycles. In a subsequent study'' the formation of a twelve-membered P4S2N6 ring as an intermediate during the thermal conversion of (Ph2PN),NSNMeZ,a P2SN3 C C C Figure 3 The structure of (Ph,PN),NSI showing 50% probability ellipsoids and the atomic numbering scheme. For clarity onl-v the a-carbon atoms of the phenyl rings are shown (Reproduced from J. Chem. SOC.,Chem. Commun. 1983 700) T. Chivers M. N. Sudheendra Rao and J. F. Richardson J. Chem. Soc. Chem. Cornmun. 1983 700.l9 T. Chivers. M. N. Sudheendra Rao and J. F. Richardson J. Chem. Soc. Chem. Commun. 1983 702. 122 F. J. Berry C C N(5) Figure 4 The structure of (Ph2PN),N2S showing 50% probability ellipsoids and the atomic numbering scheme. For clarity only the a-carbon atoms of the phenyl rings are shown (Reproduced by permission from J. Chem. SOC. Chem. Commun. 1983 700) ring at 150-185 "C into the spirocyclic compound Ph,P4N,S was reported. The intermediate (Figure 5) contains a trans dimethylamino substituent on each of the two sulphur atoms. The endocyclic S-N bond lengths were found to be considerably shorter [1.590(5) A] than the exocyclic bond lengths of 1.703(3) 8 which is close to the value expected for a S'"-N single bond.The S-N bond lengths and pyramidal geometry at N(4) suggests that there is very little .rr-bonding between the exocyclic nitrogen atom and S(1). The compound (Ph2PN),(NSNMe,) is the first example of a ring system with more than eight atoms in the mixed phosphazene-thiazyl series (R,PN),(NSR') and as such suggests that this class of inorganic heterocycles is potentially extensive. The progress of the oxidation of the trisulphur trinitride anion by molecular oxygen in acetonitrile solution and the structures of the various ions that are formed has been studied" by I5Nn.m.r. Four major products were identified SON5-,S4N50- S3N30- and S3N302-and their relative yields were shown to be a function of the flow rate of oxygen. The S3N30-and S3N302-anions were found to possess six-membered S3N3rings with the exocyclic atoms bonded to sulphur.The significant variations in chemically equivalent bond lengths and angles which were observed in both rings were associated with the electronic structures of the ions. Several studies of metal complexes of sulphur-nitrogen compounds have appeared with an investigation*' of copper(11)-N,S2 complexes of bidentate N-substituted p-aminothiones illustrating the potential relevance of such studies to current interests in metal-containing molecules of biological significance. The bis(a p-unsaturated N-substituted P-aminothione)copper(rr) complex synthesized at low T. Chivers A. W. Cordes R. T. Oakley and W. T. Pennington Inorg. Chem. 1983 22 2429. '' P. Beardwood and J. F. Gibson J.Chem. SOC.,Chem. Commun. 1983 1099. 0,S Se Te 123 Figure 5 The structure of (Ph2PN),(NSNMe,) showing 50% probability ellipsoids and the atomic numbering scheme. For clarity only the a-carbon atoms of the phenyl rings are shown (Reproduced by permission from J. Chem. SOC.,Chem. Commun. 1983 702) temperature showed intense S -Cu charge transfer bands and gave e.s.r. spectra indicative of pseudo-tetrahedral CuN2S2 co-ordination similar to that found for the type 1 centres in blue copper proteins. In another study” of the metal complexes of sulphur-nitrogen chelating agents the chemistry of palladium(I1) complexes with some monoanionic tridentate ligands of the type SNN have been reported. A report has appeared23 of the preparation of the compounds [M(OS3N2),][AsF6]2 (M = Zn or Cd) in which the metal atoms are co-ordinated by six five-membered heterocyclic OS3N ligands.The structures of these compounds determined by X-ray analysis showed the metal to be bonded to each ligand via the exocyclic oxygen atom giving a slightly distorted octahedral environment. The S3N2 rings have an envelope conformation where the sulphur atom connected to the oxygen is out of the plane formed by the other four atoms. The AsF,- group which is slightly disordered in the cadmium compound is considerably disordered in the zinc analogue. It is also interesting to record a report24 of the essentially quantitative reaction between solutions of S,NAsF in liquid sulphur dioxide and elemental 22 R. Roy S. K. Mondal and K.Nag J. Chem. Soc. Dalton Trans. 1983 1935. 23 H. W. Roesky M. Thomas J. W. Bats and H. Fuess J. Chem. Soc. Dalton Trans. 1983 1891. 24 W. V. Brooks G. K. MacLean J. Passmore P. S. White and C. M. Wong J. Chem. SOC.,Dalton Trans. 1983 1961. 124 F. J. Berry chlorine or bromine to give (SX),NAsF (X = CI or Br). The resemblance of the vibrational spectrum of (SBr),N+ to that of (SC1)2Nt of known structure was supported by a normal co-ordinate analysis of (SX),N+ which also indicated some positive interaction between the halogen atoms in (SX),N+ and which was related to the cis-planar geometry of these cations. Attempts to prepare (SF),NAsF were unsuccessful although bis(difluorothio)nitronium hexafluoroarsenate(v) (SF,),NAsF, was synthesized from the reaction of S2NAsF6 with XeF in liquid SO,F,.The structure determined by X-ray diffraction showed evidence of interac- tions between discrete (SF,),N+ and AsF,- species .and the (SF2)2N+ chain was found to possess approximately C2 symmetry with essentially eclipsed fluorine- sulphur bonds when viewed along the sulphur-sulphur axis. It is also relevant in this section on compounds containing sulphur and nitrogen to note that studies” by X-ray photoelectron spectroscopy of the S-N bonding character of carbonyl- stabilized sulphilimines and their salts have suggested a strong interaction between S+ and N-through the u bond. Substantial interest has also been shown in compounds containing sulphur and other main-group elements. It is interesting to note the attention being given to sulphur-phosphorus compounds for example the one-dimensional compound PV2S,o which has been obtained26 by heating the elements in stoicheiometric propor- tions at 490 “C in evacuated tubes.The structure consists of [V,S,,] units forming chains which are linked two by two by [PS,] tetrahedra. In these units each vanadium is surrounded by eight sulphur atoms to give a distorted bicapped triangular prism which by sharing a rectangular face with another prism forms the [V,S,,] groups in which the intercation distance implies the presence of vanadium-vanadium bonds. Only weak S-S van der Waals bonds appear to exist between the infinite double chains the majority of the sulphur atoms were described as [S-S]- pairs and the rest as s’-anions.A different mode of examination was used in the investigation2’ of the molecular structures of gaseous bis(difluorophosphino) sulphide S(PF2)2 and bis( difluorophosphino) selenide Se( PF2), which were determined by electron diffraction. Both molecules were found to have average structures with CZvsymmetry and very large amplitude torsional vibrations. Gaseous difluoro(methy1thio) phos- phine PF,(SMe) was also examined. It is interesting to note the reported cleavage of P4S3 and P,Se cage molecules by transition-metal-ligand systems.** In these experiments the reactions of tetra-phosphorus trisulphide and tetraphosphorus triselenide with [RhCl(cod)l2 (cod = cyclo-octa-1,5-diene) in the presence of triphos [triphos = 1,1,1 -tris(diphenylphosphinomethyl)ethane] was found to give compounds formu- lated as [(triphOS)Rh(P,X,)].c6H6 (X = S or Se).The X-ray crystal structure of [{MeC(CH,PPh,),)-{ M(P3S3)}].C6H showed that the (triphos)Rh moiety had replaced a basal phosphorus in the cage molecule. 25 S. Tsuchiya and M. Sano J. Chem. SOC.,Chem. Commun. 1983 413. 26 R. Brec G. Ouvard M. Evain P. Grenouilleau and J. Rouxell J. Solid Srare Chem. 1983 47 174. D. E. J. Arnold G. Gundersen D. W. H. Rankin and H. E. Robertson J. Chem. SOC.,Dalton Trans. 27 1983 1989. 28 M. Di Vaira M. Peruzzini and P. Stoppioni J. Chern. SOC.,Chem. Comrnun. 1983 903. 0,S Se Te 125 It is also interesting to note the preparation? during a study of the preferred conformations in chalcogen-substituted ylides of triphenylC(phenylselen0)-(pheny1thio)methylenel phosphorane (C,H&P=C( SC6H5)Se(C6H5) which was shown to consist of unassociated units with a planar skeleton of phosphorus selenium and sulphur atoms around the ylidic carbon atom.The phenyl rings at the chalcogen atoms were located on opposite sites of the heavy atom plane with similar angles of inclination and the overall conformation considered in terms of the minimization of lone-pair repulsions. It is also interesting to record the reported3* reaction of sulphur with the diphosphine ArP=PAr [Ar = 2,4,6-B~'~(c,H,)] which led to the isolation and subsequent X-ray structure analysis of the diphosphene monosulphide ArP(S)=PAr. When treated with hexamethylphosphorus triamide the compound reverted to the starting diphosphine but thermal and photochemical -isomerization of the compound gave the thiadiphosphirane ArP-S- PAr.Several investigations of compounds containing sulphur and arsenic have been reported. The vibrational spectra3' of solid a-and P-As4S4 and the Raman spectra of molten As,S have suggested that As,S molecules of D, symmetry are retained in the molten state. The melt was also shown to undergo partial decomposition during prolonged laser irradiation. In another a polymeric bis(sulphiny1- nitri1o)sulphur complex of silver( I) [Ag4{ S(NSO),},][AsF6],.SO2 was isolated from the reaction of AgAsF with S(NS0)2 in liquid sulphur dioxide. The structural determination showed the presence of two crystallographically independent silver atoms.One lay on a three-fold axis and was octahedrally co-ordinated by the terminal oxygens of six S(NSO)2 ligands the other occupied a general position and was unsymmetrically co-ordinated by the nitrogen atoms of three S(NS0)2ligands. The ligands were found to bridge the silver atoms to form a polymeric cationic network containing holes in which the AsF,- anions and SO2 solvent molecules were accommodated without themselves acting as ligands. In a subsequent the reaction of trimeric thioformaldehyde with AgAsF in liquid sulphur dioxide was found to give the compound [Ag2((CH2S)3},][AsF6]2.S02. X-Ray crystallography showed that the silver atoms in the isolated L,AgLAgL2 (L = ligand) cations possessed irregular co-ordination geometry with one silver being co-ordinated by four sulphurs from three ligands and the other by five sulphurs from three ligands.By far the largest interest in sulphur-containing compounds has been directed towards those containing metallic elements. Although some of these have involved straightforward studies such as the preparation3 of single crystals of a number of anhydrous sulphites of strontium barium lead cadmium and manganese by gel crystallization methods and their examination by infrared Raman and thermoana- lytical techniques the most significant attention has been given to compounds with 29 H. Schmidbaur C. Zybill C. Kruger and H. J. Kraus Chem. Ber. 1983 116 1955. 30 M. Yoshifuju K. Shibayama N. Inamoto K. Hirotsu and T. Higuchi J.Chem. SOC.,Chem. Comrnun. 1983 862. 3' V. W. Bues M. Somer and W.Brockner Z. Anorg. Allg. Chem. 1983,499 7. 32 H. W. Roesky M. Thomas P. G. Jones W. Pinkert and G. M. Sheldrick J. Chem. SOC.,Dalton Trans. 1983 1211. 33 H. W. Roesky H. Hofmann P. G. Jones W. Pinkert and G. M. Sheldrick J. Chem. SOC.,Dalton Trans. 1983 1215. 34 V. H. D. Lutz W. Buchmeier W. Eckers and B. Engelen Z. Anorg. Allg. Chem. 1983 496 21. 126 F. J. Berry potential biological relevance. In this context the synthetic Fe,S cluster has received attention as a model compound for the active site of bacterial hydrogenase and one has reported on the catalytic properties of the phenyl-lithium-activated Fe4S4C1:-cluster for hydrogenation reactions. Aspects of the chemistry of ferredoxin (Fd) proteins containing cubane-type [4Fe-4S] redox sites in which the prevalent electron-transfer process is represented as Fd,,([4Fe-4S]2+) -t e-== Fdr,,([4Fe-4S]+) have also been subject to The corresponding isoelectronic couple of synthetic analogues of these sites is [Fe,S,(SR),]*-+ e-+ [Fe4S4(SR),l3- and the structural properties of the reduced clusters [Fe,S4(SR),l3- have been examined by a single crystal X-ray analysis of [(C2H5),N]J"e4S4(S-p-C6H4Br),].The Fe,S8 containing cluster (Figure 6) has a two-fold symmetry axis and exhibits a distortion from the idealized Zd symmetry of the [4Fe-4S]+ core which is different from that of (Et3MeN)3[Fe,S,(SPh)4] 2 Figure 6 The structure ofthe Fe,S8 portion 01[Fe4S,(S-p-C,H,Br),l3-as its Et,N' salt showing 50% probability ellipsoids selected interatomic distances and the atom-labelling scheme.Primed and unprimed atoms are related by the crystallographic twozfold symmetry axis (Reproduced by permission from Inorg. Chem. 1983 22 1550) 35 H. Inoue and M. Sata J. Chem. SOC.,Chern. Cornrnun. 1983 983. 36 D. W. Stephan G. C. Papaefthymiou R. R. Trankel. and R. H. Holm Inorg. Chem. 1983 22 1550 0,S Se Te 127 and ( Et4N)3[Fe4S4(SCH2Ph)4] which are the only other structurally defined reduced clusters. Current interest in synthetic analogues for the 4Fe-4S centres in non-haem-iron proteins is also reflected in a preliminary communication3' of the synthesis and structural characterization of bis(tetrapheny1phosphonium)-bis(ethy1dithiocarbamato) -bis(thiopheno1ata) -tetrakis(p3 -sulphido)tetraferrate (Ph4P)2[Fe4S4(SPh)2( Et2dtc)J in which a new cubane type cluster with mixed ter- minal ligands and two different modes of ligation on the Fe4S4 core has been identified.It is also interesting for chemical and biological reasons to note that the system MC12-Na,(S2-o-xyl)-Li2S in a 3 :3 1 ratio in ethanol (M = Fe") or acetonitrile-ethanol (M = Co") gives the trinuclear complexes [M3S(S2-o-xyl),12- (S2-0-xyl = o-xylene-a,a'-dithiolate) which may be isolated as Et4N+ salts.38 The complexes contain an apical p3-S atom bonded to three metal atoms arranged in a nearly equilateral triangular array. Each metal atom is co-ordinated to one terminal and one bridging sulphur atom of a dithiolate ligand giving distorted-tetrahedral M"S4 units in structures approaching overall C3 symmetry.The isotopically shifted 'H n.m.r. spectra of the complexes demonstrated the retention of the solid-state structure in acetonitrile solutions. The solution phase spectral and magnetic properties were indicative of MI'S chromophores similar to those present in the mononuclear tetrahedral complexes [M(S,-o- xyl),12-. These species and the recently reported [Fe,S(S,-o-~y1)-4,5-Me~)~]~-, provide the first examples of the occurrence of discrete pyramidal M3(p3-S)fragments in weak-field complexes with the two Fe" complexes and [Fe3(p2-S),( SR),I3-being the only structurally characterized trinuclear Fe-S-SR species of abiological origin. In other structural studies of compounds containing iron and sulphur a series of binuclear sulphur- and polysulphur-bridged organoiron complexes (p-S ) -[CpFe(C0),I2 x = 1-4 and Cp = have been prepared3' by substitution reactions and in investigations4' of iron(] I) complexes of N-substituted bidentate and tetradentate thiosalicyclideneimines several spin-paired Fe'" compounds con- taining SN,-bonded tridentate ligands have been identified.Attention has also been given to compounds containing sulphur iron and other transition metals of which molybdenum and tungsten appear to be popular. For example the synthesis of the (C6H5),P+ and (C2H,),N+ salts of the [(C~HI,S)~F~S~MS~]~-and [(S5)FeS2MS2I2- complex anions (M = Mo or W) have been examined4' and X-ray crystallography has shown the [(C6H5)4P]2[S5FeS2MS2] complexes to be isomorphous and isostructural with the structural properties of the [(C6H5)4P]2[(C6H5S)2Fes~Ms~] (M = Moor W) complexes being described in detail.The ,'Fe Mossbauer chemical isomer shifts were discussed in terms of extensive Fe -+ S2MS2 charge transfer and found to be slightly smaller for the WS2-complexes than for the corresponding MoS,~-complexes. The less pronounced electron 37 M. G. Kanatzidis M. Ryan D. Coucouvanis A. Simopoulis and A. Kostikas Inorg. Chem. 1983 22 179. 38 K. S. Hagen G. Christou and R. H. Holm Inorg. Chem. 1983 22 309. 39 M. A. El-Hinnawi A. A. Aruffo B. D. Santarsiero D. R. McAlister and V. Schomaker Inorg. Chem. 1983 22 1585. 40 P. J. Marini K.S. Murray and B. 0.West J. Chem. Soc. Dalton Trans. 1983 143. 4' D. Coucouvanis P. Stemple E. D. Simhon D. Swenson N. C. Baenziger M. Draganjac L. T. Chan A. Simopoulis. V. Papaefthymiou A. Kostikas and V. Petrouleas Inorg Chem.. 1983 22 293. 128 F. J. Berry delocalization in the WS2-species was also reflected in the electronic spectra and the electrochemical properties of the complexes. Another investigation4‘ of com- pounds containing sulphur iron and tungsten is worthy of note since although dinuclear complexes containing a bridging CS2 molecule are well known the preparation and structural determination of 1,1,2,2,3,3,3,3,3-n0nacarbonyl-1,2-bis(7)-cyclopentadienyl) -p3-[sulphido( thiocarbonyl) -C(Fe’)S( Fe2)S’( W3)] -di -irontung-sten shows the existence of a novel heteronuclear complex triply-bridged by carbon disulphide.There has also been much interest in compounds containing sulphur and molyb- denum without any other transition metals. For example the refined crystal structure43 of [bis@-methoxyphenyl)diazenido][ N,N’-dimethyl-N,N’- bis(mer- captoethyl)ethylenediamine]molybdenum(vr) a molybdenum (VI) compound with a tetradentate N2S2ligand was shown to possess a surprising non-equivalence of the molybdenum-amine bonds which was attributed to ‘inherent ligand strain’. In another the stereochemistry of R2PX2- ligands (X = S2 OS or 0,)in molybdenum-containing dimers and polymers were investigated. The stereo-chemistry about molybdenum(I1) was related to the bond angle about X such that the sulphur ligand was found to accommodate much smaller angles (typically 85-100°) than oxygen.It is also pertinent to record the reported45 preparation of the complex [MoCl,(thf),] (thf = tetrahydrofuran) in high yield by the reduction of [MoCl,(thf),] in tetrahydrofuran with tin and the reaction of the complex with [NH,][S,P(OMe),] in dry methanol to give [MO(S,P(OM~),}~] in which molybdenum adopts pseudo-octahedral co-ordination. It is interesting to note that a crystal structure determinati~n~~ of bis(tetrapheny1phosphonium)heptasulphide (Ph4P),S7 which was obtained by the reaction of MoS?-with an excess of the sodium salt of the diethyldithiocarbamate anions in acetonitrile solution showed the S:-anion to be a right-handed non- branched helix with very short terminal sulphur-sulphur bonds.The chemistry of thiometallates of molybdenum has been a subject of extensive investigation and reflects the key role of these complexes in biological processes including nitrogen fixation in addition to their unusual spectroscopic and structural properties. Although the structural chemistry of sulphide-bridged dinuclear com- plexes of molybdenum have received considerable attention in the past the properties of the analogous tungsten compounds have remained largely unexplored and it is therefore interesting to note the recent structural of the newly synthesized asymmetric dinuclear complex [SzW(p-S)2W(NNMe2)2(PPh3)]in which the central tungsten is trigonally pyramidally co-ordinated and the tungsten-tungsten separation is 3.024(1) A.The study also considered the diamagnetic symmetric dinuclear com- plex [{ W(SBU‘),(PM~,P~))~(~-S)~] which has a centre of symmetry that imposes planarity on the W,S2 system and in which the W-W distance of 2.736(2)8 may be interpreted in terms of a W=W bond. The tungsten atoms were shown to possess 42 L. Busetto M. Monari A. Palazzi V. Albano and F. Demartin J. Chem. SOC.,Dalton Trans. 1983 1849. 43 R. E. Marsh and A. Toy Inorg. Chem. 1983 22 1691. 44 J. H. Burk G. E. Whitwell J. T. Lemley and J. M. Burlitch Inorg. Chem. 1983 22 1306. 45 J. R. Dilworth and J. A. Zubieta J. Chem. Soc. Dalron Trans. 1983 397. 46 M. G. Kanatzidis N. C. Baenziger and D. Coucouvanis Inorg. Chern. 1983 22 290. 47 J. R. Dilworth R.L. Richards P. Dahlstrom J. Hutchinson S. Kumar and J. Zubieta J. Chem. SOC. Dalton Trans.. 1983 1489. 0,S Se Te 129 distorted trigonal bipyramidal geometry with the bridging sulphide and phosphorus species adopting apical sites. In another study48 which reflects the current interests in the tetrathiometallate anions of MeV' and Wv’ the ability of the reagents to co-ordinate to later transition metals which in the case of molybdenum has biological significance have been considered. In this investigation the utility of the copper thiomolybdates for the investigation of biological antagonism between copper and molybdenum which leads to copper deficiency in ruminant animals prompted the preparation spectroscopic and structural characterization of [(PhS)CuS2MoS2I2- and [(PhS)CuS,MoS2(SPh)l2- which are new additions to the family of discrete copper( I)-tetrathiomolybdate complexes.In investigation^^^ of new binary trinuclear Mo-S species M03S92-(and its tungsten analogue) has been prepared by heating (NH4)2MS4 (M = Mo or W) in N,N-dimethylformamide. The crystal structure of the (PPh4),Mo3S9 complex showed two external tetrahedral MoS units chelating a central square-pyramidal MoS unit. These Mo3Sg2-complexes were formulated as mixed-valence compounds and described in terms of a centred MoIV flanked by two MoV1 ions. In a study of cis-dinitrosylmetal complexes of Cr Mo and W with sulphur- containing chelating ligands,” octahedral complexes of the type cis-[M(chelate),(NO),] (M = Cr Mo or W) were prepared by the reactions of the solvent-stabilized dihalogenodinitrosylmetal fragments [MX,( (MX = CrCl, MoBr2 WBr,; solv = acetone or acetonitrile) with dithio chelating anions (chelate-= (CH,),AsS2- (CH3),PS,- (CH30),PS2- or (CH3),N-CS2-).Addi-tional chromium complexes using other chelating ligands were also reported. In another investigation” the preparation of several mono- and bis-thiolato mixed thiolato-monoalkylamido and thiolato-alkoxy complexes of nitrosyl[tris(3,5-dimethylpyrazolyl)borato] molybdenum were reported and the crystal and molecular structure of [MO{HB(~,~-M~,C,N~H)~)(NO)I(SC~H, ,)I described. A different type of interest is reflected in a study” of the electronic properties of the tetrathiotung- state(v1) ion [WS4J2-,as its [NH,]+ and [NBu,]’ salts by low temperature absorption and resonance Raman spectroscopy.Compounds containing sulphur and copper have also received noticeable attention as is exemplified in the first reports3 of a metal-promoted trimerization of carbon disulphide from the reaction of the complex [(PPh,),Cu(q2-BH,)] with CS2 to give the dinuclear copper(1) complex [(PPh3)2Cu(p-S2CSCH2SCS2)Cu(PPh3)2]. The X-ray crystal structure showed the two (PPh,),Cu fragments to be held together by a bridging S2CSCH2SCS22- ligand formed from a double head-to-tail condensation of three CS molecules. In another preliminary report54 the Cu-S-Cu angles in the cyclic molecule (p-SPh)3C~3(PPh3)4, which possesses a twist conformation and which is different from the planar (p-SPh)3Fe3 ring in [Fe3(SPh),C1,I3- were found to vary from 87 to 124” but to correlate with the inclination of the S-C bonds to 4n S.R. Acott C. D. Garner J. R. Nicholson and W. Clegg 1.Chem. SOC.,Dalton Trans. 1983 713. 49 W. H. Pin M. E. Leonowicz and El Stiefel Inorg. Chem. 1983 22 672. 50 M. Herberhold and L. Haumaier Chem. Ber. 1983 116 2896. ” J. A. McCleverty A. S. Drane N. A. Bailey and J. M. A. Smith 1.Chern. Soc. Dalton Trans. 1983 91. 52 R. J. H. Clark T. J. Dines and G. P. Proud J. Chem. Soc. Dalton Trans. 1483 2019. 53 C. Bianchini C. A. Ghilardi A. Meli S. Midollini and A. Orlandini J. Chem. SOC.,Chem. Cornrnun. 1983 545. 54 1. G. Dance L. J. Fitzpatrick and M. L. Scudder. I. Chem. Soc. Chem. Comrnun. 1983. 546. 130 F.J. Berry their Cu-S-Cu planes and to relate to the conformations of similar cycles in metallo-cysteine proteins. The attention currently being given to compounds of biological relevance is also reflected in as mentioned previously continued interest in the blue copper proteins and is further illustrated in studies” of the synthesis structures and electrochemistry of copper(I1) mercaptide complexes. In another study the (1,4,8,11-tetra-azacyclotetradecane)copper( I I) cation Cu(cyclam)” has been reported56 to react with pentafluorothiophenolate in alcohol solvents to give the complex formulated as Cu(cy~larn)(SC,F~)~. The six-co-ordinate complex was shown to be tetragonally elongated and to contain a square array of equatorial Cu-N bonds and weakly bonded axially disposed thiolate anions in which the Cu-S distances of 2.94 8 are comparable with the axial Cu-S bond in plastocyanin.The optical and e.s.r. spectra of the complex were associated with the effects of the axial thiolates on the electronic properties of the Cu” ion. Several studies of analogous copper and nickel compounds have also been reported. The synthesis of the novel mixed-donor nitrogen-sulphur macrocyclic ligand 1-thia-4,7-diazacyclononanehas been described5’ and its complexes with copper(rr) and nickel(I1) reported. The electronic spectra for the two complexes were discussed and the crystal structure of the nickel complex related to the possible origins of the high ligand-field strengths of the macrocycles. In another an improved method for preparing 1,4,7-trithiacycIononaneand the structures of its nickel(Ir) cobalt(r I) and copper(r1) complexes were described.The reactions of carbon disulphide with a number of nickel(o)-phosphine complexes has been reported59 to give two classes of Ni-CS2 co-ordination. Compounds containing sulphur and other first-row transition-metals illustrate other areas of current interest. For example bis(pentamethylcyc1open-tadienyl)vanadium(lI) has been shown6’ to bond to disulphur ligands to form [T~-(C~M~~)~V(~~-S~)~ which contains the persulphido ligand. In a study6‘ of thiocyanate-bridged transition-metal polymers the structural electronic and mag- netic properties of some mono (2,2’-bipyridyl) transition-metal thiocyanates prepared by thermolytic decomposition of the corresponding monomeric bis(bipyridy1) com- plexes have been reported.Results from X-ray diffraction near-infrared- visible- infrared- and e.s.r.-spectroscopy were consistent with a description of the complexes as polymeric zigzag chains with stepwise metal-thiocyanate bridging groups and six-co-ordinate metal centres (Figure 7). Sulphur-manganese compounds have also been examined in a study62 of the interaction of manganese(r1) with amino-acids and bidentate and tridentate ligands containing nitrogen oxygen and/or sulphur donor atoms. Other aspects of the solid-state chemistry of sulphur-containing compounds are illustrated by the reported63 phase diagrams of the quaternary systems MS-Cr2S3- In2S3 (M = Co Cd or Hg) and the investigations of these materials by high 55 0.P. Anderson C. M. Perkins and K. K. Brito Inorg. Chem. 1983 22 1267. 56 A. W. Addison and E. Sinn Inorg. Chem. 1983 22 1225. 57 S. M. Hart J. C. A. Boeyens J. P. Michael and R. D. Hancock J. Chern. SOC.,Dalton Trans. 1983 1601. 58 W. N. Setzer C. A. Ogle G. S. Wilson and R. S. Glass Inorg. Chem. 1983 22 266. 59 M. G. Mason P. N. Swepston and J. A. Ibers Inorg. Chem. 1983 22 41 I. 60 S. Gambarotta C. Floriani A. Chiesi-Villa and C. Guastini J. Chem. SOC.,Chem. Commun. 1983 184. 6’ B. W. Dockum G. A. Eisman E. H. Witten and W. M. Reiff Inorg. Chem. 1983 22 150. 62 R. K. Boggess J. R. Absher S. Moreless L. T. Taylor and J. W. Hughes Inorg. Chem. 1983 22 1273. 63 H. D. Lutz W.W. Bertram B. Oft and H. Haeuseler. J. Solid State Chem. 1983. 46. 56. 0 S Se Te 13 1 cis-Thiocyanate -N cis-Thi 0cymate-S rlio CI Ic =2 2'-bipyridine r?I S 'C IN Ic I Figure 7 Proposed polymer structure for Mn(bpy)( NCS)* and Co(bpy)(NCS) (Reproduced by permission from Inorg. Chem. 1983 22 150) temperature X-ray diffraction X-ray powder diffraction d.t.a. t.g.a. and far-infrared spectroscopy. Complete series of mixed crystals were formed among the spinel-type compounds MCr2S4 MIn2S4(M =Cd or Hg) and In2S3. In the sections CoCr2S,- CoIn2S4 and CoCr,S4-In2S relatively large miscibility gaps were found to exist as a result of a change from normal to inverse spinel structure. The interchangeability of both systems was found to increase with increasing temperature and at tem- peratures exceeding 1000 "C complete series of solid solutions were formed which 132 E J.Berry could be quenched to ambient temperature. Superstructure ordering similar to that of ordered a-In$ was found in the indium-rich region of the MIn2S4-In2S3 solid solutions. It is also interesting to note the preparation and examination of the crystallographic and magnetic properties of members of the systems CoI-,Ru,S2 (0 < x < 1) and Fthl-,Ru,SZ (0.5 < x < 1). From a comparison with the system CO,-~R~,S~ it was proposed that the 4d electrons of Rh(4d’) are localized in the presence of Co(3d7) but delocalized in the presence of Ru(4d6). The magnetic susceptibility of the system Co -,Ru S2was found to be sensitive to the homogeneity of the products and indicative of the behaviour of Ru(4d6) as a diamagnetic ion.Informative SCF-Xa-SW calculations have been carried on the model compounds [M(X,)(PH,),]+ (M = Rh or Ir; X = S or Se) during an investigation of the electronic structure and bonding in complexes containing side-on bonded disulphur and diselenium. The calculations predicted an X-X bond order of about 1 and revealed that the M-X2 covalent interaction increases along the sequence RhSe2 < IrSez < RhS < IrS2. The side-on bonded S2 and Se groups were con- sidered as molecules with excited configuration and the M-S2 and M-Se bonds described in terms of in-plane 7~ overlap of an S2 or Se2 7~;forbital with a metal px + d, hybrid of predominantly px character and of a overlap of a metal 6 + pz hybrid with S2 or Se ‘rrll and pa orbitals.The interest in compounds containing sulphur and second- or third-row transition- metal elements has also been maintained. For example sulphur-containing dinuclear rhodium complexes such as [Rh2(p-SBu‘),(CO),{ P( OMe),},] have been reported66 to catalyse selectively the hydroformylation of hex-1-ene at low pressure and tem- perature. The synthesis of new rhenium nitrene complexes has been described6’ and the trans-Re(OC2H5)(p- NC6H4Me)(S2CNMe2) compound shown to contain six-co- ordinate rhenium in a distorted octahedral environment. In a study68 of di-and tri-thiocarbamate complexes of osmium a novel (selenodithiocarbamato) diosmium complex [OS~(CL-S~S~CNM~~)~(S,~NM~~),]PF~, was reported and the crystal struc- ture (see section on selenium) described.The complex [OS,(S~CNM~,)~]CI was also examined and shown to possess two isomeric structures which thermally interconvert in a manner similar to that identified in the ruthenium analogues. Complexes of the type Os[S2CNR2I3 were shown by ‘H n.m.r. to lack stereochemical rigidity. Interest in a variety of compounds containing sulphur and either platinum or palladium has also been evident and given the doubt concerning the struc- tural properties of some of these materials it is important to note the recent69 study of tetrasulphido[1,2-bis(diphenylphosphino)ethane]platinum(11). The [PtS4(Ph2PCH2CH2PPh2)] complex was found (Figure 8) to be approximately square planar and the tetrasulphido-ligand to behave as a dianionic chelating ligand with the resulting ptS4ring adopting approximately C2conformation.A molecular orbital 64 J. Foise K. Kim J. Covino K. Dwight A. Wold R. Chianelli and J. Passaretti Inorg. Chem. 1983 22 61. 65 A. P. Ginsberg J. H. Osborne and C. R. Sprinkle Inorg. Chem. 1983 22 254. 66 P. Kalck J. M. Frances P. M. Pfkter T. G. Southern and A. Thorez J. Chem. SOC.,Chem. Commun. 1983 510. 67 G. V. Goeden and B. L. Haymore Inorg. Chern 1983 22 157. 68 L. J. Mahen G. L. Miessler J. Berry M. Burow and L. H. Pignolet Inorg. Chem. 1983 22 405. 69 C. E. Briant M. J. Calhorda T. S. A. Hor,N. D. Howells and D. M. P. Mingos J. Chem. soc. Dalton Trans. 1983 1325.0,S Se Te 133 S(3) Figure 8 Molecular sfructure of [PtS,(dppe)] for clarity the hydrogen atoms on the phenyl rings have been omitted (Reproduced from J. Chem. SOC., Dalton Trans. 1983 1325) analysis of the bonding in this and related complexes was used to account for the observed alternation in S-S bond lengths within the PtS4 rings. In another study,” the dynamic ’ H n.m.r. spectra of several palladium(ii) complexes of cyclic sulphides in CHzC12 solution were measured at pressures up to 220MPa and the results considered in terms of the inversion process at sulphur and the achievement of ring planarity. The halogen oxidation reaction of tetrakis(dithioacetato)diplatinum(ii) has also been reported7’ and compounds of formula Pt2(MeCS2)4X2 (X = C1 Br or I) which have a formal oxidation state of +3 synthesized and characterized as diamagnetic compounds consisting of dimeric Pt2sSx2 units.Another product of formula R2(MeCS),I with formal oxidation state 2.5 was isolated from a reaction with a R:I ratio of 1 :0.5. X-Ray crystallography showed the structure to consist of linear chains of ...ptzSs...I...Pt2Ss...I... units stacking along the crystallographic b axis and to represent the first example of a linear-chain compound having dimeric [Pt2Ss] chromophores bridged through halides with a nearly symmetrical metal- halogen-metal bridge. The maximum powder electrical conductivity at 300 K of 7 X i2-I cm-’ showed an exponential temperature-dependence with a very low activation energy and was associated with a ‘hopping-type’ mechanism.Attention has been given7’ to the H20-S02-02 system because of its relevance to important processes such as sulphur dioxide-induced steel corrosion and the atmospheric oxidation of SO2to H2S04 which is a cause of environmental acidifica- tion. Given that the mechanism of the reactions especially the frequently rate 70 R. L. Batson-Cunningham H. W. Dodgen J. P. Hunt and D. M. Roundhill J. Chem. SOC. Dalron Trans. 1983 1473. ” C. Bellitto A. Flamini L. Gastaldi and L. Scaramuzza Inorg. Chem. 1983 22 444. 72 A. Stromberg 0.Gropen U. Wahlgren and 0.Lindquist Inorg Chem. 1983 22 1129. I34 F. J. Berry determining S'" +S"' oxidation step is poorly understood it is pertinent to record the series of a6 initio calculations on the sulphite ion SO:- and hydrogen sulphite ion HS03-or SO,OH- which were considered in terms of the polarization of the S'" electron pair.Another ab initio study was performed73 on the S02-HF complex and the most stable geometry found to be when the HF moiety was near to the S-0 bond separation of 1.8 A. Tetrathiafulvalene (TTF) and its derivatives have been of recent interest since it was found that with suitable acceptors they could form charge-transfer salts which behave as organic metals with high conductivity. A report74 of the preparation of tetraformyltetrathiafulvalene(TFTTF) with the potential to yield polyfunctionalized TTF from which a tetravinyl derivative could be readily obtained and which was shown by complexation with tetracyanoquinodimethane to be a good .rr-donor is therefore of considerable significance.The current interest in organic metals is also illustrated by the report75 of a new series of radical-cation salts based on an alkylated tetrathiafulvalene which were prepared by electro-oxidation of 2-(4,5-dimethyl- 1,3-dithiol-2-ylidene)-5,6-dihydro-4H-cyclopenta- 1,3-dithiole and which exhibited very promising electrical conductivity. In another the exposure of highly purified samples of the new polymers poly(2,5-thienylene sulphide) PTS and poly(2,5- thienylene selenide) PTSe to arsenic pentafluoride was found to give conducting complexes of which that derived from PtSe was superior. The results contrast with the behaviour of the poorly conducting poly(p-phenylene selenide) and conducting poly@-phenylene sulphide) complexes of AsF,.It is interesting to record the preparation" of tetrakis(trifluoromethylthiazyl) (CF,SN), which is stable at -30°C for a few days and which oligomerizes on standing for seven days at 20 "C to form a solid which melts above 180"C.It is also interesting to note that both Me,SiNSO and Me3SiN=S=NSiMe3 with tin tetrachloride to give the 1 :1 adduct Me3SiN=S=NSiMe3. SnCI in which the sulphur di-imide functions as a bidentate ligand. 4 Selenium Several important studies of selenium-containing compounds have been covered in the section dealing with s~lph~r'~~~~-~'~~~~~~~~~ and a few others warrant further comment here. For example it is pertinent to record that the Raman spectra recorded3' from As,Se were interpreted in terms of a cradle-type molecule possessing DZd symmetry and that the mechanism of selenium incor-poration in the (se1enodithiocarbamato)diosmium complex,68 [Os2(p-SeS2CNMe2)2(S,CNMe2)3]PF,,in which the selenium atoms occupy the bridging positions (Figure 9) was considered in terms of the initial bonding and activation of Se by osmium.Investigations of the solid-state chemistry of selenium-containing compounds have frequently stemmed from the technological interest in such compounds. For ?3 M. V. Friedlander J. M. Howell and A.-M. Sapse Inorg. Chem. 1983 22 100. 74 A. Gorgues P. Batail and A. Le Coq J. Chem. SOC.,Chem. Commun. 1983 405. 75 J. M. Fabre L. Giral E. Dupart C. Coulon and P.Delhaes J. Chem. SOC.,Chem. Commun. 1983,426. 76 K.-Y. Jen N. Benfaremo M. P. Cava W.-S. Huang and A. G. MacDiarmid J. Chem. SOC.,Chem. Commun. 1983 633. I7 D. Bielefeldt and A. Haas Chern. Ber. 1983 116 1257. 78 H. W. Roesky H. G. Schmidt M. Noltemeyer and G. M. Seldrick C'hem. Ber. 1983 116 1411. 0,S Se Te 135 Figure 9 Structure of the [OS,(S~S,CNM~,),(S,CNM~~)~]+ cation. The thermal ellipsoids are drawn with 30% probability boundaries (Reproduced by permission from Inorg. Chem. 1983 22 405) example recent years have seen the development of films of various metal chal- cogenides with semiconducting properties for application in various fields of tech- nology. It is interesting therefore to note the report79 of a solution growth technique for the deposition of thin films of degenerate and p-type semiconducting copper(r1) selenide.It is also relevant to record the preparation" of the compounds Nb2Se2Br, Nb2Te,Br, and Nb,Te21 from the elements in sealed quartz ampoules at 1073 K. The crystalline solids exhibiting metallic lustre and insensitive towards moisture and oxygen were shown by d.t.a. to undergo several reversible thermal transitions with temperature. The structures were found to consist of one-dimensional infinite chains of halogen-bridged Nb,(Y,)X (Y = Se or Te; X = Br or I) units containing side-on bonded Nb and Y dumbells forming quasi-tetrahedral Nb2Y2clusters. The structural and magnetic properties were consistent with the expected presence in these compounds of Nb4+ and Y-.X-Ray powder diffraction analysis at 300 K of CuGaSe and CuGaTe under high pressure showed8' a volume-induced transition '' A. Mondal and P. Pramanik J. Solid State Chem. 1983 47 81. H. F. Franzen W. Houle and H. G. V. Schnering 2. Anorg. Allg. Chem. 1983 497 13. '' V. A. Kraft G. Kuhn and W. Moiler Z. Anorg. AIIg. Chem.. 1983 504. 155. 136 F. J. Berry from the chalcopyrite-type to the NaCl structure for CuGaSe at 12.5 GPa and for CuGaTe at 8GPa. The new compound SrGa2Se has also been preparedg2 and shown to be a novel variant of the T1Se-structure-type. Some selenogermanates(1v) have been synthesizeds3 from aqueous solutions by reactions of alkali selenides with germanium diselenide and the compound Na,Ge,Se,. 16H20 obtained from syn- theses involving 1 :1 reactant ratios.The structure was shown to consist of isolated Ge2Sez- anions containing edge-sharing tetrahedra which are hydrogen bonded through Se. .-H-0 bridges to the hydrated octahedral [Na(H20)6]+ ions. The adamantane-like Ge,Se ,$-species was formed from similar reactions involving I :2 molar ratios of alkali selenide to GeSe,. In a studys4 of channel structures based on octahedral frameworks the crystal structures of TITi,Seg T1V5Se, and TICr,Seg were described and discussed in terms of their relationships with the TlV& and TlCr3S hollandite and psilomelane structures. It is pertinent to record the preparationg5 of [se,I'],,,,[AsF,-] which was shown by single crystal X-ray diffraction to consist of ASF6- species and polymeric strands of [Se,I'],,.The cation (Figure 10) was found to contain hexaselenium rings of chair conformation similar to that of cyclohexaselenium which were joined to two 0 Figure 10 View of the polymeric [Se,I'], cations (AsF,-omitted) showing the close contacts between chains (Reproduced by permission from J. Chem. Soc. Chem. Commun.,1983 526) 82 V. W. Klee and H. Schafer Z. Anorg. Allg. Chem. 1983 499 145. 83 V. B. Krebs and H. Muller Z. Anorg. Allg. Chem. 1983 496 47. 84 K. Klepp and H. Boller 1.Solid Stare Cbem. 1983 48 388. 85 W. A. Shantha Nandana J. Passmore. and P. S. White J. Chem. Sor. Cbem. Commun. 1983 526. 0,S Se Te 137 neighbouring hexaselenium rings by two weak [2.736(3) A] exocyclic 1,4 axial selenium-iodine bonds.The [Se,I+] cation is important because it is the first example of a derivative of a selenium ring and even more interestingly is a derivative of the recently discovered Se rather than the well known Se ring. The polymeric nature of the cation contrasts with the S71+species and may imply that selenium oxides such as Se,O and Se80 if they can be prepared may also have polymeric structures. Several trifluoro- and tribromo-selenate(1v) compounds of the type MSeOF and MSeOBr3 (M = K Cs or Me,N) have been examineds6 by infrared and Raman spectroscopy. The results were consistent with trigonal bipyramidal structures as predicted by VSEPR in which the oxygen atom and lone pair adopt equatorial positions. Anion polymerization via oxygen or halogen bridging which was very weak for MSeOF (M = K or Cs) became significant for KSeOCI and Me4NSeOBr3.Compounds with larger cations were found to contain isolated SeOX,- anions. The structures7 of the para-elastic phase of RbHSe04 which was determined at 387 K by neutron diffraction is interesting since it consists of chains of hydrogen bonded SeO groups extending along the crystallographic b axis. Two different types of hydrogen bond were characterized with the hydrogen in the shorter bond being disordered and consistent with the participation of hydrogen ordering in the phase transition to the ferroelectric phase. The interest in selenium complexes as organic metals has been mentioned earlier,76 and given that the novel two-dimensional metallic structure and superconductivity in charge-transfer salts of bis(ethy1enedithio)tetrathiafulvalene (BEDT-TTF) has been a significant development in organic metals research it is important to note the first reported, synthesis of the selenium analogue of BEDT-TTF bis(ethy- lenedise1eno)tetraselenofulvalene (BEDSe-TSeF) its characterization and the pre- paration of several charge-transfer salts of this new .rr-donor.The synthesis of dibenzotetraselenofulvalene (DBTSF) has also been reported89790 and the molecular structure (Figure 11) showns9 to be very similar to that of its sulphur-containing homologue (DBTTF) but with a larger molecular size resulting from the generally longer Se-C bonds. The DBTSF donor is also more chair shaped than DBTT’F and the intermolecular stacking is less dominant than the Se...Se intermolecular contacts which are close to the van der Waals separation.In this sense the structural motif of DBTSF is more reminiscent of the closely related tetramethyltetraselenaful-valene TMTSF. The preparation and characterization of several charge-transfer salts of DBTSF (ranging from insulators to metals) has also been rep~rted.~~’~~ In a study” of new tris( N,N-dialkyldiselenocarbamato)iron( ~v) tetrafluoroborate complexes four compounds of composition [Fe’V(Se2CNR2)3]+ where R = C2H5 or CH2C6Hs R2N = piperidino or morpholino were prepared as BF4- salts and examined by variable-temperature magnetochemistry Mossbauer- e.s.r.- and X-ray nh J. Milne and P. Lahaie Inorg. Chem. 1983 22 2425.87 J. Brach D. J. Jones and J. Roziere J. Solid State Chem. 1983 48 401. 88 V. Y. Lee E. M. Engler R. R. Schumaker and S. S. P. Parkin J. Chem. SOC.,Chem. Commun. 1983,235. 89 K. Lerstrup M. Lee F. M. Wiygul T. J. Kistenmacher and D. 0.Cowan J. Chem. SOC.,Chem. Commun. 1983 294. 90 I. Johannsen K. Bechgaard K. Mortensen and C. Jacobsen J. Chem. SOC.,Chem. Commun. 1983,295. P. Deplano E. F. Trogu F. Bigoli E. Leporati M. A. Pellinghelli D. L. Perry R. J. Saxton and L. J. Wilson J. Chem. Soc.. Dalton Trans.. 1983 25. 138 F. J. Berry Figure 11 The (010) projection of the crystal structure of DBTSF. The molecule labelled A is centred at (0 0 0) while molecule B is centred at d 0,i). Selenium atoms are shaded and closest Se.-.Se contacts (A) are indicated (Reproduced by permission from J.Chem. SOC. Chem. Commun. 1983 294) photoelectron-spectroscopies. The molecular structure of [Fe{ Se,CN(CH2C6HS)2}3- BF,] was determined by X-ray crystallography and shown (Figure 12) to possess D3 macrosymmetry with the FeSe core having six selenium donor atoms at the apexes of a co-ordination polyhedron which is intermediate between the idealized trigonal prismatic and trigonal antiprismatic geometries. The study showed the tris-diselenocarbamate complexes to be low-spin iron( IV) species with Fe'"Se cores and similar to their tris-dithiocarbamate counterparts. In other investigations of selenium-containing compounds the crystal structure"' of {[(C6HS)~P]2CSe)~+Fe20Cl~-.4cH2C12 has been shown to possess a linear Fe-0-Fe axis and selenium-selenium bond whilst the complex [Ir(Se,)-(Me2PCH2CH2PMe2)2]CI has been found93 to contain a five-membered IrSe ring.The structure determination of [Ba-2.2.2-Crypt]Se4.en has shown9 the hitherto unknown Se;- anions to be significant structural units. The new compound (mor- pholinecarbodiselenoato)selenium(II) iodide [OC,H,NCSe3]I has been reported95 and described in terms of polymeric - - -1. .Sea. -1- -.Sea -1. -chains running along the c-axis and held together by van der Waals contacts. Finally it is relevant to note 92 H. Schmidbaur C. E. Zybill and D. Neugebauer Angew. Chern. Int. Ed. Engl. 1983 22 156. 93 A. P. Ginsberg J. H. Osborne and C. R. Sprinkle Inorg. Chern. 1983 22 1781. 94 V.T. Konig B. Eisenmann and H. Schafer Z. Anorg. Allg. Chem. 1983 498 99. 95 F. Bigoli E. Leporati M. A. Pellinghelli G. Crisponi P. Deplano and E. F. Trogu 1. Chern. Soc. Dalton Tranc. 1983 1763. 0,S Se Te 139 C(25) Figure 12 Perspective view of the cation in [Fe{Se2CN(CH2C,H,),},IBF looking down the three-fold axis (Reproduced by permission from J. Chem. SOC. Dalton Trans. 1983 25) that elemental selenium has been found96 to be sparingly soluble in solutions of selenium dioxide in concentrated hydrochloric acid and the yellow solutions have been shown by gravimetric analysis and spectrophotometric studies to contain Se2C12 as the principal species in equilibrium with SeOCl,. 5 Tellurium Studies of some solid tellurium-containing compounds have been cited in the previous section^.^^^^^^' More specific interest in such materials is illustrated in the Vh M.Mahadevan and J. Milne Innrg. Chern.. 1983. 22. 1648. 140 F. J. Berry investigationY7 of the copper-tellurium system by d.t.a. d.s.c. and X-ray diffraction which enabled the construction of a phase diagram from which the phases described as Cu2_.,Te Cu3- rTe2 and CuTe have been defined. Several superstructures were observed in the homogeneity ranges of the non-stoicheiometric phases. Another binary compound of interest is Re,Te, which has been reported9' to crystallize in a new structure type having space group Pbca. This new [M,X,,] cluster compound formulated as {[Re,Te,]Te,} was shown to contain octahedral [Re,] clusters and the tellurium atoms were found to be amenable to replacement by selenium.Mixed oxides containing tellurium have also been subjected to examination. Compounds from the tellurium-molybdenum-oxygen and tellurium-vanadium- oxygen systems have been investigated" by e.s.r. and 12'Te Mossbauer spectroscopy. The data were interpreted in terms of the cationic oxidation states and their environ- ments and associated with the catalytic properties of these materials for the selective oxidation and ammoxidation of hydrocarbons. The reduction of Te2V209 by hydro-gen at temperatures between 300 and 450 "Chas been studied'" by X-ray diffraction e.s.r.- and infrared-spectroscopy and the process envisaged as being initiated by the formation of oxygen vacancies which give several types of transient V02+species.Further slow reduction up to ca. 350°C was found to give rise to the formation of TeVO,., and minor amounts of P-TeVO and at higher temperatures the binary oxides were shown to undergo rapid decomposition to V203. The magnetic interac- tion between the paramagnetic V4' ions in the products were related to the structural properties of the reduced oxides. The preparation of Pu,02Te has been reported"' and found to be isostructural with the corresponding rare-earth oxide tellurides which crystallize in the tetragonal La202Te-type system. Magnetic susceptibility data recorded between 4 and 298 K together with resistivity measurements showed Pu202Te to be an antiferrornagnet below 56 K and a semiconductor with an intrinsic energy gap of 0.65 eV.A new method for the synthesis of hypofluorites using fluorine fluorosulphate as the fluorinating agent has been applied'" to the synthesis in high yields of the new hypofluorite TeFSOF. This compound and related species were characterized by infrared Raman I9F n.m.r. and mass spectrometry. The preparation of new tellurium-nitrogen compounds containing the 5N-TeF group have been repor- tedlo3 and the material CI,Se=NTeF has been shown to be a rare example of a compound containing a discrete selenium-nitrogen double bond. The OTeF com- pounds of P As and Sb such as POF,-OTeF, P(OTeF,), O=P(OTeF,), As(OTeF,), and Sb(OTeF,) have also been describedIo4 and compgred with similar and characterized compounds. 97 R.Blachnik M. Lasocka and U. Walbrecht J. Solid Stare Chem. 1983 48 431. 98 F. Klaiber W. Petter and F. Hulliger J. Solid State Chem. 1983 46 122. 99 F. J. Berry and M. E. Brett Inorg. Chim. Acra 1983 68 25. I00 F. Cariati L. Esre G. Micera and J. C. J. Bart Z. Anorg. Allg. Chem. 1983,496 159. 101 J. M. Costantini D. Damien C. H. de Novion A. Blaise A. Cousson H. Abazli and M. Pages J. Solid State Chem. 1983 41 219. lo* C. J. Schack W. W. Wilson and K. 0.Christe Inorg. Chem. 1983 22 18. I03 M. Hartl P. Huppmann D. Lentz and K. Seppelt Inorg. Chem. 1983 22 2183. I04 D. Lentz and K. Seppelt 2. Anorg. Allg. Chem. 1983 502 83. 0,S Se Te 141 Investigations of telluronium salts formed from the reaction of NaTeR (R = p-EtOC6H or Ph) with organic dihalides (CH2),,X2 (n = 1,2,3 or 4) have shown'05 that when n = 1 (X = Br or I) the products may be formulated as charge-transfer complexes of stoicheiometry (RTe),CH2.CH2X2 whereas when n = 2 the elimina- tion of ditelluride gives rise to the formation of an alkene.The study demonstrated the NaTeR compound to be an effective dehalogenating agent for uic-dihalides. The '"Te Mossbauer parameters for (p-EtOC,H,Te),CH2.CH2Br were interpreted in terms of the removal of Sp-electron density from the spare-pair orbital uia the charge-transfer interaction. A kinetic and mechanistic study of the reaction between bis-p-ethoxyphenyl ditelluride and molecular iodine in solution has also been reported."' An investigationlo' of the crystal and molecular structure of [NBuil- [PhTeCl,I] has shown the arytellurium mixed halide anion PhTeC1,I- to be a square-based pyramid with a lone pair in the sixth position of an octahedron.The structure of the novel p,-Te[Mn(CO),( q2-C5H5)] complex has been foundlo8 to contain an almost planar p,-TeMn skeleton in which the central tellurium atom can be considered to function as a six-electron donor. It is also interesting to note the report'O' of the synthesis reactivity and n.m.r. spectra of (C5H,)RhFe,Te2(CO) (x = 6 or 7). Ius K. G. Karnika de Silva Z. Monsef-Mirzai and W. R. McWhinnie J. Chem. SOC.,Dalton Trans. 1983 2143. I06 R. T. Mahdi and J. D. Miller J. Chem. SOC.,Dalton Trans. 1983 1071. ID7 N. W. Alcock and W. D. Harrison J. Chern. SOC.,Dalton Trans.1983 2015. I08 M. Herberhold D. Reiner and D. Neugebauer Angew. Chem. Ini. Ed. Engl. 1983 22 59. I09 D. A. Lesch and T. B. Rauchfuss Inorg. Chern. 1983 22 1854.