Metal Vapor Synthesis as a Straightforward Route to Group 10 Homoleptic Carbene Complexes

Abstract

The co-condensation of nickel, palladium, or platinum vapor with the N, N ‘-di- tert -butyl heterocyclic carbene 1,3-di- N - tert -butylimidazol-2-ylidene [C{N(Bu t )CH} 2 ] (L) provides a novel and straightforward synthesis of the stable, two-coordinate homoleptic metal carbene complexes NiL 2 ( 1 ), PdL 2 ( 2 ), and PtL 2 ( 3 ). A single-crystal X-ray structural determination of 2 and 3 shows the two complexes to be isomorphous; in the solid state the metal center is linear and two-coordinate and the molecules approach D 2 d symmetry with a dihedral angle of 90° between the planar rings of the two ligand heterocycles. The metal center in 2 appears to be an essential mediator in the quantitative conversion of the ligated carbene into dihydroimidazoline, which is cleanly eliminated from a solution of the complex under an atmosphere of dihydrogen; 2 also reversibly coordinates ethene.