Ligand Substitution Processes on Carbonylmetal Derivatives. 3.1Reaction of Hydridopentacarbonylchromates with Phosphines

Abstract

The reaction of K+[HCr(CO)5]- with phosphanes PR3 (R = Et, Ph, NMe2) in THF at 65 °C affords the disubstituted complexes trans-Cr(CO)4(PR3)2 isolated in 57−70% yield. The X-ray crystal structures of trans-Cr(CO)4(PR3)2 derivatives have been determined for R = Et and NMe2. These reactions proceed first by exchange of one carbon monoxide ligand, generating the monosubstituted hydridotetracarbonylchromates K+[HCr(CO)4PR3]-, observed and characterized by NMR spectroscopy for R = Et and Ph. The second step involves substitution of the hydride ligand of K+[HCr(CO)4PR3]- to give the disubstituted derivatives trans-Cr(CO)4(PR3)2. These ligand exchange processes are discussed and compared with the reaction of phosphanes with the dinuclear bridged K+(μ-H)[Cr(CO)5]2-.