Synthesis of the Unsaturated [MMoCp(µ-PR2)(CO)5]– Anions (M = Mn, R = Ph; M = Re, R = Cy): Versatile Precursors of Heterometallic Complexes

An efficient synthetic route for the preparation of the title anions was implemented, and it involved two-electron reduction of iodide-bridged [MMoCp(µ-I)(µ-PR2)(CO)5] (Cp = cyclopentadienyl) complexes by using Na(Hg). Reaction of these anions with (NH4)PF6 (in THF) and ClSnPh3 (in MeCN) gave [MMoCp(µ-H)(µ-PR2)(CO)5(NH3)] and [MoReCp(µ-PCy2)(SnPh3)(CO)5(NCMe)] (Cy = cyclohexyl), respectively, with incorporation of the corresponding electrophile at either a bridging (H+) or terminal (SnPh3) position and the addition of an external ligand (NH3 and NCMe, respectively) to render electron-precise derivatives (dMo–Re > 3.1 A). In contrast, reaction with [AuCl{P(pTol)3}] yielded stable unsaturated trimetallic [AuMMoCp(µ-PR2)(CO)5{P(pTol)3}] clusters (dMo–Mn = 2.71 A).