093 V(SBut)4 IC - Inorg. Chem. 1991, 30, 300-305 300...

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300 Inorg. Chem. 1991, 30, 300-305 Contribution from the Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, and Lawrence Livermore National Laboratory, Livermore, California 94550 Preparation and Properties of Mononuclear Vanadium Thiolates: Structural Characterization the [V(SBut),l0' Pair and C-S Bond Cleavage in V(SBU')~ in the Gas Phase Dwight D. Heinrich,la Kirsten Folting,Ia John C. Huffman,Ia John G. Reynolds,**lb and George Christou*.Ia Received May 7, 1990 The synthesis and properties of mononuclear vanadium complexes with BUS- ligation are reported. Treatment of VCI,(THF), with NaSBu' and Bu'SSBu' in MeCN leads to high-yield isolation of V(SBu'), (1). In contrast, treatment of VC13(THF)3 with NaSBu' and 2J'-bipyridine (bpy) leads to the VI' salt [V(SBuP(bpy)J [V(SBu'),] (2). Complex 1 crystallizes in space group P&l,c with (at -158 "C) u = b = 11.034 (12) A, c = 9.253 (9) , and Z = 2. Complex 2 crystallizes in space group PZ,/n with (at -142 "C) u = 21.309 (9) A, b = 15.592 (6) A, c = 17.151 (7) A, and Z = 4. The structures of 1 and 2 were solved by using 483 (F > 3.0a(F)) and 2102 (F > Z.Oo(F)) unique reflections in the range 6" 5 28 5 45" and refined to values of R (R,) of 3.96 (4.00) and 8.54% (7.69%), respectively. The structure of 1 consists of a mononuclear four-coordinate V(SBU')~ unit with imposed 4 (S,) symmetry, corresponding to a slight flattening from Td symmetry. The V-S distances are 2.2184 (24) A. Complex 2 contains an anion that is the one-electron-reduced version of 1; there is no imposed symmetry, but the geometry can be again described as distorted tetrahedral. The V-S bonds (2.280 (7)-2.309 (7) A) are slightly longer than those in 1, as expected for the lower oxidation state. The cation geometry of 2 is distorted octahedral with two chelating bpy groups and two BUS- ligands in cis positions. Complex 1 was investigated by cyclic voltammetry (CV) in CH2C12; it was found to undergo a reversible one-electron reduction at -0.68 V vs SCE and an irreversible one-electron oxidation at +0.81 V. The EPR spectrum of 1 in toluene solution at room temperature shows a typical eight-line hyperfine-structured signal with pi, = 1.970 and Ai, = 55 G. At 163 K in a toluene glass, an axially symmetric spectrum is obtained with gu = 1.961, g, = 1.975, A,, = 108 G, and A, = 28 G; these parameters are compared to those for V(OBu'), and differences shown to be as expected for the 0 vs S substitution. The electron ionization mass spectral (EIMS) behavior of 1 has been investigated and its fragmentation pattern elucidated. The major fragmentation modes involve sequential loss of C,H9 by C-S bond cleavage to yield [V(SBut)&3,]' (x = 0-4) ions and S atom loss leading to ions of general formulation [V(SC,H9)$3y]' = I, 2; y = 2) and [VS,]' = 0-3). No evidence for one-step loss of an entire SC,H9 fragment is observed. The relevance of these results to several catalytic processes in the petroleum industry are described, including the mechanism by which V2S3 is formed during upgrading of heavy crudes containing vanadyl impurities and the use of colloidal VS, particles as hydrodesulfurization catalysts in slurry-type processes.
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093 V(SBut)4 IC - Inorg. Chem. 1991, 30, 300-305 300...

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