title: Synthesis and structures of ruthenium-NHC complexes and their catalysis in hydrogen transfer reaction.
abstract: Ruthenium complexes [Ru(L1)2(CH3CN)2](PF6)2 (1), [RuL1(CH3CN)4](PF6)2 (2) and [RuL2(CH3CN)3](PF6)2 (3) (L1= 3-methyl-1-(pyrimidine-2-yl)imidazolylidene, L2 = 1,3-bis(pyridin-2-ylmethyl)benzimidazolylidene) were obtained through a transmetallation reaction of the corresponding nickel-NHC complexes with [Ru(p-cymene)2Cl2]2 in refluxing acetonitrile solution. The crystal structures of three complexes determined by X-ray analyses show that the central Ru(II) atoms are coordinated by pyrimidine- or pyridine-functionalized N-heterocyclic carbene and acetonitrile ligands displaying the typical octahedral geometry. The reaction of [RuL1(CH3CN)4](PF6)2 with triphenylphosphine and 1,10-phenanthroline resulted in the substitution of one and two coordinated acetonitrile ligands and afforded [RuL1(PPh3)(CH3CN)3](PF6)2 (4) and [RuL1(phen)(CH3CN)2](PF6)2 (5), respectively. The molecular structures of the complexes 4 and 5 were also studied by X-ray diffraction analysis. These ruthenium complexes have proven to be efficient catalysts for transfer hydrogenation of various ketones.
authors.affiliation: College of Life Sciences, Huzhou University, Huzhou 313000, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, China.
authors.forename: Chunxin
authors.initials: C
authors.lastname: Lu
authors.affiliation: College of Life Sciences, Huzhou University, Huzhou 313000, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: College of Life Sciences, Huzhou University, Huzhou 313000, China.
authors.forename: Shengliang
authors.initials: S
authors.lastname: Ni
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou 310007, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou 310007, China.
authors.forename: Wanzhi
authors.initials: W
authors.lastname: Chen
keywords: N-heterocyclic carbene; ruthenium; transfer hydrogenation