Preparation, Characterization, and Catalytic Properties of Ruthenium(II) Nitrosyl Complexes with α-Diimine Ligands

Reactions of Ru(NO)Cl3·5H2O with α-diimines have yielded new Ru(II) complexes fac-[(N−N)Ru(NO)Cl3] [N−N = R′NC(R)C(R)NR′, R = Me, R′ = 2,6-dimethylphenyl, ligand a; 1; R = Me, R′ = 2,6-diisopropylphenyl, ligand b, 2; R = H, R′ = 2,6-diimethylphenyl, ligand c, 3; R = H, R′ = 2,6-diisopropylphenyl, ligand d, 4; R = H, R′= 2,6-cyclohexyl, ligand e, 5], mer-[(N−O)Ru(NO)Cl3] [N−O = (E)-1-(4-amino-3,5- diisopropylphenyl)-2-(2,6-diisopropylphenylimino)ethanone; 6], and cis-[(N−N)2RuCl2] [N−N = e; 7]. An unprecedented N,O ligand was formed from ligand d in 6, as revealed by its X-ray crystal structure. Molecular structures of 1, 2, 4, and 7 have also been determined by X-ray crystallography. 1, 2, and 4 exhibit six-coordinate octahedral geometry around the central Ru atom, which is ligated by two nitrogen atoms from the α-diimine ligand, three chlorine atoms in the facial configuration, and the nitrogen atom of the NO ligand. Studies of catalytic properties of 1−5 show they are efficient catalyst precursors for the transfer hydrogenation of ketones. 3−5 also exhibit catalytic activities in atom transfer radical polymerization of styrene.