Synthesis and Structural Characterization of an Unusual Platinum π-Arene Complex: (η6-C6H3Me3)Pt[(C2F5)2PMe]Me+

Treatment of cis-(dfmp)(2)PtMe2 (dfmp = (C2F5)(2)PMe) with the mesitylenium acid (C6Me3H4)B+-(C6F5)(4)(-) in 1,2-difluorobenzene cleanly produces an unusually stable arene complex, [(eta(6)-C6Me3H3)Pt(dfmp)(CH3)](+) (B-(C6F5)(4))(-) (1). Facile arene exchange and competitive binding equilibria have been quantified for mesitylene relative to toluene (K = 0.0030(3)) and durene (K = 20(2)). Reaction of 1 with H-2 at 80 degrees C results in hydrogenolysis to form the arene hydride (eta(6)-C6Me3H3)Pt(dfmp)(H)(+) (2), while treatment of 1 with CO gives trans-(dfmp)(2)Pt(CO)Me+ as the major phosphine product. Addition of excess Me3P to 1 results in both arene and dfmp displacement to form (Me3P)(3)PtMe+center dot (eta(6)- C6Me3H3)Pt(dfmp)(CH3)(+) is a moderately active ethylene dimerization catalyst to form 2-butenes (similar to 7 TO h(-1), 20 degrees C).