title: Synthesis, Structure, and Properties of Molybdenum and Tungsten Cyano Complexes with Cuboidal M(4)(&mgr;(3)-E)(4) (M = Mo, W; E = S, Se, Te) Cores.
abstract: Four new tungsten and molybdenum cyano complexes of formula KCs(5)[W(4)S(4)(CN)(12)].CH(3)OH.2H(2)O (1), K(6)[W(4)Se(4)(CN)(12)].6H(2)O (2), K(6)[W(4)Te(4)(CN)(12)].5H(2)O (3), and K(7)[Mo(4)Te(4)(CN)(12)].12H(2)O (5) have been prepared by high-temperature 430-450 degrees C reaction of the polymeric chain compounds {W(3)S(7)Br(4)}(x)(), {W(3)Se(7)Br(4)}(x)(), {Mo(3)Te(7)I(4)}(x)() and solid-state WTe(2) with KCN, and crystallization from aqueous solutions. In addition Cs(6)[Mo(4)Te(4)(CN)(12)].2H(2)O (4) has been prepared by oxidation of 5 with bromine water. The molecular structures have been investigated by X-ray crystallography. Mixed-valence (3.5) compounds 1-4 are diamagnetic. Mixed-valence (3.25) compound 5 is paramagnetic (&mgr; = 2.03 &mgr;(B) at 77 K). In addition to the structural data for these complexes IR and UV-vis spectroscopy have been used to characterize the complexes. Cyclic-voltammetry data have shown that M(4)E(4)(n)()(+) (M = Mo, W; E = S, Se, Te) cubes are capable of existing in three oxidation states ranging from the most oxidized (n = 6; 10 electrons) to the most reduced electron-precise (n = 4; 12 electrons). The (77)Se, (125)Te, and (183)W NMR spectra of the cubes (1-3) demonstrate unambiguously the unaltered environments of the W and E atoms in aqueous solution.
authors.affiliation: Department of Chemistry, The University of Newcastle, Newcastle upon Tyne, NE1 7RU, U.K.
authors.forename: V. P.
authors.initials: VP
authors.lastname: Fedin
authors.forename: I. V.
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authors.lastname: Kalinina
authors.forename: D. G.
authors.initials: DG
authors.lastname: Samsonenko
authors.forename: Y. V.
authors.initials: YV
authors.lastname: Mironov
authors.forename: M. N.
authors.initials: MN
authors.lastname: Sokolov
authors.forename: S. V.
authors.initials: SV
authors.lastname: Tkachev
authors.forename: A. V.
authors.initials: AV
authors.lastname: Virovets
authors.forename: N. V.
authors.initials: NV
authors.lastname: Podberezskaya
authors.forename: M. R. J.
authors.initials: MR
authors.lastname: Elsegood
authors.forename: W.
authors.initials: W
authors.lastname: Clegg
authors.forename: A. G.
authors.initials: AG
authors.lastname: Sykes