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

Abstract

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-(CF 3 ) 2 C 6 H 3 ] 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.