Reactivity of the unsaturated dimolybdenum anion [Mo2(η5-C5H5)2(μ-PCy2)(μ-CO)2]- towards electrophiles based on p- and d-block elements

Article abstract of DOI:10.1016/j.jorganchem.2009.09.023

The 30-electron binuclear anion [Mo₂Cp₂(μ-PCy₂)(μ-CO)₂]^- reacts with the chlorophosphite ClP(OEt)₂ or the organotin chlorides Cl₂SnPh₂ or ClSnPh₃ to give compounds of the formula trans-[Mo₂Cp₂(μ-E)(μ-PCy₂)(CO)₂], (E = P(OEt)₂, SnPh₃, SnPh₂Cl). In contrast, this anion reacts with the organosilicon chlorides ClSiR₃ (R = Ph, Me) to give unstable silyloxycarbyne-bridged complexes [Mo₂Cp₂(μ-PCy₂)(μ-COSiR₃)(μ-CO)], which rapidly hydrolyze to give the known hydride [Mo₂Cp₂(μ-H)(μ-PCy₂)(CO)₂]. Two main types of products were also observed in the reactions of the title anion with different chlorocomplexes of the transition and post-transition metals. Thus, the reactions with [MCl₂Cp₂] (M = Ti, Zr) give moisture-sensitive isocarbonyl-bridged complexes of the type [Mo₂Cp₂(μ-COMClCp₂)(μ-PCy₂)(μ-CO)]. In contrast, softer metallic electrophiles such as [AuCl(PR₃)] (R = ⁱPr, ptol) react with the anion at the dimolybdenum site to form new trimetallic clusters of the formula [AuMo₂Cp₂(μ-PCy₂)(CO)₂(PR₃)], also retaining a Mo-Mo triple bond. Subsequent reactions of the latter products with the solvate complexes [Au(PR₃)(THF)][PF₆] give the tetranuclear clusters [Au₂Mo₂Cp₂(μ-PCy₂)(CO)₂(PR₃)₂][PF₆] (Mo-Mo = 2.5674(3) A? and Au-Au = 2.7832(2) A? when R = ⁱPr). Finally, the reaction of the title anion with HgI₂ gives the pentanuclear cluster [Hg{Mo₂Cp₂(μ-PCy₂)(CO)₂}₂] or the trinuclear cluster [Mo₂Cp₂(μ-HgI)(μ-PCy₂)(CO)₂] depending on the stoichiometry being actually used for the reaction. The trinuclear species is only stable in tetrahydrofuran (THF), and decomposes to give a mixture of the dimeric species [Mo₂Cp₂(μ-HgI)(μ-PCy₂)(CO)₂]₂ along with variable amounts of the known iodide-bridged complex [Mo₂Cp₂(μ-I)(μ-PCy₂)(CO)₂].