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

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) Å and Au−Au = 2.7832(2) Å 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].