Pt^II-Catalyzed Ethylene Hydrophenylation: Influence of Dipyridyl Chelate Ring Size on Catalyst Activity and Longevity

Expansion of the dipyridyl ligand from a five- to six-membered chelate for Pt^II-catalyzed ethylene hydrophenylation provides an enhancement of catalyst activity and longevity. Mechanistic studies of [(dpm)­Pt­(Ph)­(THF)]­[BAr′₄] [dpm = 2,2′-dipyridylmethane, and Ar′ = 3,5-(CF₃)₂C₆H₃] attribute the improved catalytic performance at elevated temperatures to a favorable change in entropy of activation with an increase in chelate ring size. The Pt^II catalyst precursor [(dpm)­Pt­(Ph)­(THF)]­[BAr′₄] is among the most active catalysts for ethylene hydrophenylation by a non-acid-catalyzed mechanism