Synthesis of the Bifunctional Phosphinidene Cluster, Fe3(CO)9(μ3-PH)2, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Abstract

The synthesis and systematic study of the reaction chemistry of a bifunctional phosphinidene cluster, Fe3(CO)9(μ3-PH)2 (3) is reported. Reaction chemistry at one P−H functional site is effectively communicated through the Fe3(CO)9 core, and impacts on the reactivity of the second P−H site. Deprotonation of the acidic protons in 3 allows access to a lone electron pair on phosphorus. The first proton is readily removed with NEt3/[PPN]Cl ([PPN]+ = (Ph3P)2N+) to produce the [PPN]+ salt of [Fe3(CO)9(μ3-PH)(μ3-P)]- ([4]-). Removal of both phosphorus-bound hydrogen atoms in 3 requires the use of 2 equiv of n-BuLi, to produce Li2[Fe3(CO)9(μ3-P)2] (Li2[5]). Quenching of Li2[5] with MeOH-d4 generates [Fe3(CO)9(μ3-PD)(μ3-P)]-. The lone electron pairs on the cluster-bound phosphorus atoms undergo analogous reaction chemistry to organophosphines. Alkylation at the phosphorus site is carried out by reaction of [Et3NH][4] with MeOSO2CF3 generating the monosubstituted cluster, Fe3(CO)9(μ3-PMe)(μ3-PH) (6) as the primary p...