Reversible Inter- and Intramolecular Carbon-Hydrogen Activation, Hydrogen Addition, and Catalysis by the Unsaturated Complex Pt(IPr)(SnBut3)(H)

Abstract

The complex Pt(IPr)(SnBut3)(H) (1) was obtained from the reaction of Pt(COD)2 with But3SnH and IPr [IPr = N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Complex 1 undergoes exchange reactions with deuterated solvents (C6D6, toluene-d8, and CD2Cl2), where the hydride ligand and the methyl hydrogen atoms on the isopropyl group of the IPr ligand have been replaced by deuterium atoms. Complex 1 reacts with H2 gas reversibly at room temperature to yield the complex Pt(IPr)(SnBut3)(H)3 (2). Complex 2 also undergoes exchange reactions with deuterated solvents as in 1 to deuterate the hydride ligands and the methyl hydrogen atoms on the isopropyl group of the IPr ligand. Complex 1 catalyzes the hydrogenation of styrene to ethylbenzene at room temperature. The reaction of 1 with 1 equiv of styrene at -20°C yields the η2-coordinated product Pt(IPr)(SnBut3)(η2-CH2CHPh)(H) (3), and with 2 equiv of styrene, it forms Pt(IPr)(η2-CH2CHPh)2 (4).