The compound can be formulated as ininvin1s7 11 there

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Unformatted text preview: 900pm long.(64) 64H. DEISEROTH HAN E%-SON, Angew. Chem. I nt. J. and Edn. Engl. 20, 962-3 (1981). Ch. 7 In6S7 (and the isostructural In6Se7) have a curious structure comprising two separate blocks of almost ccp S which are rotated about the baxis by 61" with respect to each other; the In is in octahedral coordination. The compound can be formulated as In'(In~')'VIn~1S7-11. There are also numerous ternary IdTl sulfides in which In' has been replaced by Tl', e.g.: Tl'In~'S8, Tl'Iny'S5, Tl'In"'S2, T : In111S3,T1'(In~n)~In'''S6, 1 T1:In1In:'S8 and T1'(In~1)'VIn~1S7.(64a) The crystal structures of In4Se3 and Ir4Te3 show that they can be regarded to a first approximation as In![In3]"(X-")3 but the compound does not really comprise discrete ions. The triatomic unit [In"l-Inlll-In"'] is bent, the angle at the central atom being 158" and the In-In distances 279 pm (cf. 324-326 pm in metallic In). However, it is also possible to discern non-planar 5 membered heterocycles in the structure formed by joining 2 In from 1 {In3}to the terminal In of an adjacent (In3}via 2 bridging Se (or Te) atoms so that the structure can be represented schematically as in Fig. 7.17. The In"'-Se distances average 64aH.DIESEROTHnd R.WALTHER, . a norg. allg. Chem. J. a Z 622, 611-16 (1996). Figure 7 1 Schematic structure of In4Se3. .7 97.3.5 Other inorganic compounds 2 69pm compared with the closest In'-Se contact of 297pm. The unit can be compared with the isoelectronic species [Hg;]". The compound T1&, which has the same stoichiometry as IwX3, has a different structure in which chains of corner-shared {Tl"'S4} tetrahedra of overall stoichiometry [TlS3] are bound together by Tl'; within the chains the Tl"'-S distance is 254 pm whereas the TI'-S distances vary between 290-336pm. A comparison of the formal designation of the two structures In'[(In~')]V(SeC")~ and (T1')~[T111'S3]-11'again illustrates the increasing preference of the heavier metal for the +1 oxidation state. The trend continues with the polysulfides TI'S2, TliS, and TI& already alluded to on p. 253. Compounds with bonds to N, P, As, Sb or Bi The binary compounds of the Group 13 metals with the elements of Group 15 (N, P, As, Sb, Si) are structurally less diverse than the chalcogenides just considered but they have achieved considerable technological application as 111-V semiconductors isoelectronic with Si and Ge (cf. BN isoelectronic with C, p. 207). Their structures are summarized in Table 7.10: all adopt the cubic ZnS structure except the nitrides of AI, Ga and In which are probably more ionic (less covalent or metallic) than the others. Thallium does not form simple compounds 255 Table 7.10 Structures of 111-V compounds MX'") B Ga In W S S S W S S S W S S S M+ N P As Sb ~~~ A1 L, s S S XJ. ~ ( a)L= B N layer lattice (p. 208). S = sphalerite (zinc blende), cubic ZnS (p. 1210). W = wurtzite, hexagonal ZnS stmcture (p. 1210). M"'Xv: the explosive black nit...
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This note was uploaded on 10/12/2012 for the course CHEMISTRY CHM1040 taught by Professor Jhon during the Spring '12 term at Florida A&M.

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