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Chemistry of Unsaturated Group 6 Metal Complexes with Bridging Hydroxy and Methoxycarbyne Ligands. 6. C−E Bond Formation and C−O Bond Cleavage Processes in the Reactions of [Mo25-C5H5)2(μ-COMe)(μ-PCy2)(μ-CO)] with Several p-Block Elements (E) and Their Hydride Derivatives

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posted on 2010-05-10, 00:00 authored by M. Esther García, Daniel García-Vivó, Miguel A. Ruiz
The unsaturated complex [Mo2Cp2(μ-COMe)(μ-PCy2)(μ-CO)] (1) reacts with several HERn molecules (HERn = HSPh, HPHPh, HSnPh3) in toluene at 263−288 K to give the corresponding derivatives [Mo2Cp2(μ-ERn)(μ-PCy2)(CO)2]. A related reaction takes place in toluene at 263 K with the diphosphite (EtO)2POP(OEt)2 to give a mixture of the diethoxyphosphide derivatives [Mo2Cp2(μ-PCy2){μ-P(OEt)2}(CO)2] and [Mo2Cp(η5-C5H4CH2Ph)(μ-PCy2){μ-P(OEt)2}(CO)2], the latter incorporating a benzyl group from the solvent, and with iodine (in dichloromethane at room temperature) to give first the iodide complex [Mo2Cp2(μ-I)(μ-PCy2)(CO)2] and then the triiodide derivative [Mo2Cp2(μ-I)I2(μ-PCy2)(CO)2]. In all of the above reactions, neat demethylation of the methoxycarbyne ligand takes place. In contrast, the silanes HSiPh3 and H2SiPh2 (unreactive toward 1 in refluxing toluene) react slowly under visible−UV irradiation at room temperature to give in good yields the novel complexes [Mo2Cp2{μ-C(2-C6H4SiPh2OMe)}(μ-PCy2)(μ-CO)] and [Mo2Cp2(μ-CSiPh2OMe)(μ-PCy2)(μ-CO)], having arylcarbyne and silylcarbyne ligands, respectively, the latter resulting from the overall elimination of H2 and insertion of Ph2SiC6H4 and SiPh2 fragments, respectively, into the strong C−OMe bond of the carbyne ligand. The reactions of 1 with elemental selenium and sulfur involve the incorporation of three to four chalcogen atoms to the dimetal center under mild conditions, to give respectively the carbene-seleniolate derivative [Mo2Cp2{μ-C(OMe)C(O)Se}(μ-PCy2)(μ-Se2)] and the O-methyldithiocarbonate [Mo2Cp2(μ-PCy2){μ-S2C(OMe)}(S)2], the latter derived from an unexpected coupling of two sulfur atoms to the carbyne ligand.

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