title: Synthesis, structures and catalytic activities of ruthenium(ii) carbonyl chloride complexes containing pyridine-functionalised N-heterocyclic carbenes.
abstract: A series of ruthenium(II) carbonyl chloride complexes with pyridine-functionalised N-heterocyclic carbenes, trans(Cl)- and cis(Cl)-[Ru(Py-NHC)(CO)2Cl2] [Py-NHC = 3-tert-butyl-1-(2-pyridyl)imidazol-2-ylidene, 1a and 1b; 3-n-butyl-1-(2-pyridyl)imidazol-2-ylidene, 2a and 2b; 3-tert-butyl-1-picolylimidazol-2-ylidene, 3a and 3b; 3-n-butyl-1-picolylimidazol-2-ylidene, 4a and 4b; 3-benzyl-1-picolylimidazol-2-ylidene, 5a and 5b] have been prepared by transmetallation from the corresponding silver carbene complexes and characterised by elemental analyses, infrared and 1H and 13C NMR spectroscopies. The yields of trans(Cl)- and cis(Cl)-isomers could be controlled by altering the reaction conditions: the trans-isomers were kinetically formed as the main products in 60-70% yield in CH2Cl2 at ambient temperature while the thermodynamic cis-isomers were obtained as the major products in 70-80% yield in toluene at refluxing temperature. The trans-isomer was transformed into the thermodynamic cis-isomer by heating in CH2Cl2 in a Teflon-lined stainless autoclave for 24 h at 120 degrees C. The molecular structures of 1a, 1b, 2b, and 4b have been determined by single-crystal X-ray diffraction. These complexes showed catalytic activities in hydrogen transfer reactions of ketones.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Cheng
authors.forename: Hui-Jun
authors.initials: HJ
authors.lastname: Xu
authors.forename: Jia-Feng
authors.initials: JF
authors.lastname: Sun
authors.forename: Yi-Zhi
authors.initials: YZ
authors.lastname: Li
authors.forename: Xue-Tai
authors.initials: XT
authors.lastname: Chen
authors.forename: Zi-Ling
authors.initials: ZL
authors.lastname: Xue
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D011725:Pyridines; C030011:carbene; D012428:Ruthenium; C023666:pyridine; D008697:Methane