Syntheses, Structures, and Catalytic Properties of Ruthenium(II) Nitrosyl Complexes with Pyridine-Functionalized N-Heterocyclic Carbenes

Ruthenium(II) nitrosyl complexes with pyridine-functionalized N-heterocyclic carbenes [(L)Ru(NO)Cl-3] [L = 3-tert-butyl-1-(2-pyridyl)imidazol-2-ylidene, 2a; 3-n-butyl-1-(2-pyridyl)imidazol-2-ylidene, 2b; 3-tert-butyl-1-picolylimidazol-2-ylidene, 2c; 3-n-butyl-1-picolylimidazol-2-ylidene, 2d; and 3-benzyl-1-pico-lylimidazol-2-ylidene, 2e] have been prepared by transmetalation from the corresponding silver carbene complexes. Compounds 2a-c have been characterized by single-crystal X-ray crystallography. Compounds 2a-e show catalytic activities in transfer hydrogenation of ketones.