High Yield Synthesis and Reactivity of a Phosphinidene Bridged Dimolybdenum Complex

Protonation of [Mo2Cp2(μ-H)(μ-PHR*)(CO)4] (Cp = η5-C5H5, R* = 2,4,6-C6H2tBu3) with HBF4·OEt2 gives the hydridophosphinidene complex [Mo2Cp2(μ-H)(μ-PR*)(CO)4]BF4, which is easily deprotonated with H2O to give the known phosphinidene complex [Mo2Cp2(μ-PR*)(CO)4] in 95% yield. Reaction of the latter with I2 gives the unsaturated phosphinidene complex [Mo2Cp2I2(μ-PR*)(CO)2], which exhibits an intermetallic distance of 2.960(2) Å. Irradiation of solutions of [Mo2Cp2(μ-PR*)(CO)4] with UV light gives a mixture of the triply bonded [Mo2Cp2(μ-PR*)(μ-CO)2] and the hydridophosphido derivative [Mo2Cp2(μ-H){μ-P(CH2CMe2)C6H2tBu2}(CO)4] as major species. The latter complex results from an intramolecular C−H bond cleavage from a tBu group and has been characterized by spectroscopy and an X-ray study. Irradiation in the presence of HC⋮C(p-tol) results in the insertion of the alkyne into the Mo−P bond to give [Mo2Cp2{μ-η:η,κ-C(p-tol)CHPR*}(CO)4] structurally characterized through an X-ray study.