Reactions of zerovalent olefin complexes of platinum with carbon monoxide

Abstract

The reaction of platinum(0) olefin complexes with carbon monoxide at room temperature in hydrocarbon solvents was monitored gasvolumetrically and shown to give an unstable amorphous platinum(0) carbonyl derivative characterized by a CO:Pt molar ratio of 2 under the best conditions (low temperature, atmospheric pressure). The product of the olefin substitution by CO may be regarded as an intermediate towards the formation of platinum metal, whose diffraction pattern was detected upon heating the carbonylated product at about 250°C. The carbonylation product is highly reactive at room temperature towards di-iodine or the bidentate tertiary phosphine dppe giving PtI 2(CO) 2 or Pt(dppe) 2 , respectively, in substantially quantitative yields. The present findings suggest the following relative affinity for platinum(0): dppe>CO>olefin. Steric congestion of the olefin ligands preventing the platinum atoms from readily forming metal–metal bonds presumably explains the experimentally established isolation of platinum(0) olefin complexes by Stone and coworkers.