Reactivity of the unsaturated dimolybdenum anion [Mo 2(η 5-C 5H 5) 2(μ-PCy 2)(μ-CO) 2] − towards electrophiles based on p- and d-block elements

Abstract

The 30-electron binuclear anion [Mo 2Cp 2(μ-PCy 2)(μ-CO) 2] − reacts with the chlorophosphite ClP(OEt) 2 or the organotin chlorides Cl 2SnPh 2 or ClSnPh 3 to give compounds of the formula trans-[Mo 2Cp 2(μ-E)(μ-PCy 2)(CO) 2], (E = P(OEt) 2, SnPh 3, SnPh 2Cl). In contrast, this anion reacts with the organosilicon chlorides ClSiR 3 (R = Ph, Me) to give unstable silyloxycarbyne-bridged complexes [Mo 2Cp 2(μ-PCy 2)(μ-COSiR 3)(μ-CO)], which rapidly hydrolyze to give the known hydride [Mo 2Cp 2(μ-H)(μ-PCy 2)(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 [MCl 2Cp 2] (M = Ti, Zr) give moisture-sensitive isocarbonyl-bridged complexes of the type [Mo 2Cp 2(μ-COMClCp 2)(μ-PCy 2)(μ-CO)]. In contrast, softer metallic electrophiles such as [AuCl(PR 3)] (R = i Pr, ptol) react with the anion at the dimolybdenum site to form new trimetallic clusters of the formula [AuMo 2Cp 2(μ-PCy 2)(CO) 2(PR 3)], also retaining a Mo−Mo triple bond. Subsequent reactions of the latter products with the solvate complexes [Au(PR 3)(THF)][PF 6] give the tetranuclear clusters [Au 2Mo 2Cp 2(μ-PCy 2)(CO) 2(PR 3) 2][PF 6] (Mo−Mo = 2.5674(3) Å and Au−Au = 2.7832(2) Å when R = i Pr). Finally, the reaction of the title anion with HgI 2 gives the pentanuclear cluster [Hg{Mo 2Cp 2(μ-PCy 2)(CO) 2} 2] or the trinuclear cluster [Mo 2Cp 2(μ-HgI)(μ-PCy 2)(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 [Mo 2Cp 2(μ-HgI)(μ-PCy 2)(CO) 2] 2 along with variable amounts of the known iodide-bridged complex [Mo 2Cp 2(μ-I)(μ-PCy 2)(CO) 2].