Synthesis and Reactivity of Methylpalladium Complexes Bearing a Partially Saturated IzQO Ligand

S. Akita, R. Nakano, S. Ito, K. Nozaki*
Organometallics 2018, 37, 2286–2296. DOI: 10.1021/acs.organomet.8b00263

Abstract: A saturated N-heterocyclic carbene–phenolate bidentate ligand, 3,3a,4,5-tetrahydroimidazo[1,5-a]quinolin-9-olate-1-ylidene (SIzQO), was synthesized and characterized. The SIzQO ligand was then treated with PdClMe(pyridine)2 and [Pd(μ-Cl)Me(2,6-lutidine)]2, which afforded cis-C,C-(SIzQO)PdMe(pyridine) and the thermodynamically unstable trans isomer trans-C,C-(SIzQO)PdMe(2,6-lutidine), respectively. The latter isomerizes at 40 °C into the corresponding cis isomer via a dissociative mechanism. These palladium/SIzQO complexes catalyze the polymerization of ethylene at 100–120 °C, although the catalytic activity is lower than that of a previously reported palladium/imidazo[1,5-a]quinolin-9-olate-1-ylidene (IzQO) system.

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