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Carbon−Sulfur and Carbon−Halogen Bond Cleavage of Acyclic or Cyclic Thioethers, Thiophenes, and Dihaloalkanes with the Trithiolato-Bridged Cation [Mo2Cp2(μ-SMe)3(MeCN)2]+

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journal contribution
posted on 25.01.2010, 00:00 by Wilfried-Solo Ojo, François Y. Pétillon, P. Schollhammer, Jean Talarmin
Reactions of the trithiolato-bridged complex [Mo2Cp2(μ-SMe)3(MeCN)2](BF4) (1) with acyclic (e.g., Et2S) or cyclic (e.g., thiirane, thietane, tetrahydrothiophene, 1,4-dithiane, and 1,4-thioxane) thioethers and chalcogenophenes (benzothiophene, benzoselenophene, and dibenzothiophene) in dihaloalkanes led to either the thioether- and halide-bridged compounds [Mo2Cp2(μ-SMe)2(μ-SRR′)(μ-X)](BF4) (R = R′ = Et, X = Cl (3); RR′ = C4H8, X = Cl (10), X = Br (11) ; RR′ = C4H8O, X = Cl (14)), and dithioether- and chloro-bridged derivatives [Mo2Cp2(μ-SMe)2(μ-Cl){μ-κ1(S),κ1(S)-(SR′′x(CH2)nSR′′x}](BF4) (x = 1, R′′ = Me, n = 1 (4); x = 0, n = 4 (13)) or the μ-sulfido complex [Mo2Cp2(μ-SMe)3(μ-S)](BF4) (6) and the methyl 1,3-propylthiolate thioether-bridged compound [Mo2Cp2(μ-SMe)2{μ-κ2(S),κ2(S)-S(CH2)3SMe}](BF4) (8), according to the structural features of the organic sulfur reagents. Ring-opening reaction through the cleavage of C−S bonds occurred when small-ring thioethers (e.g., thiirane and thietane) are used as reagents, whereas facile C−X (X = Cl, Br) bond cleavage was observed for other sulfur molecules. Some reactions that were conducted in chlorocarbon solvents (e.g., CH2Cl2, (CH2)2Cl2) gave rise to the formation of the oxo-bridged complex [Mo2Cp2(μ-SMe)3(μ-O)](BF4) (7) as a byproduct with moderate yields. All new complexes have been characterized by elemental analyses and spectroscopic methods, supplemented for the tetraphenylborate or hexafluorophosphate salts of 4, 68, 10, and 13 by X-ray diffraction.