Pt^II-Catalyzed Hydrophenylation of α-Olefins: Variation of Linear/Branched Products as a Function of Ligand Donor Ability

Abstract

The Pt II complexes [( x bpy)Pt(Ph)(THF)] + ( x bpy = 4,4′-X 2 -2,2′-bipyridyl; x = OMe ( 1a ), t Bu ( 1b ), H ( 1c ), Br ( 1d ), CO 2 Et ( 1e ) and NO 2 ( 1f )] catalyze the formation of n -propylbenzene and cumene from benzene and propene. The catalysts are selective for branched products, and the cumene/ n -propylbenzene ratio decreases with increasing donor ability of the x bpy ligand. DFT(D) calculations predict more favorable activation barriers for 1,2-insertion into the Pt–Ph bond to give branched products. The calculations indicate that 1,2-insertion of propene should be faster than 2,1-insertion for all Pt(II) catalysts studied, but they also indicate that cumene/ n -propylbenzene selectivity is under Curtin–Hammett control.