Generation and Reactivity of Methylphosphaketene in the Coordination Sphere of Tungsten

The [4 + 2] cycloadduct between the 1-methyl-2-keto-1,2-dihydrophosphinine
pentacarbonyltungsten complex and dimethyl acetylenedicarboxylate
can be used as a precursor for the methylphosphaketene tungsten complex
under UV irradiation at room temperature. Under these conditions,
the phosphaketene complex easily loses CO to give the methylphosphinidene
complex. Highly reactive alcohols and primary alkylamines trap both
the phosphaketene and the phosphinidene complexes. Less reactive phenol
and bulky amines together with alkynes and conjugated dienes only
trap the phosphinidene complex.