[1-tert-Butyl-3-(pyridin-2-ylmethyl-κN)imidazol-2-ylidene-κC 1]carbonyldichlorido(dimethyl sulfoxide-κS)ruthenium(II)

In the title complex, [RuCl2(C13H17N3)(C2H6OS)(CO)], the coordination environment around the Ru atom is slightly distorted octahedral. The Cl atoms are mutually trans to the dimethyl sulfoxide ligand and the imidazole carbene C atom, respectively. The carbonyl ligand is located trans to the pyridine N atom.

In the title complex, [RuCl 2 (C 13 H 17 N 3 )(C 2 H 6 OS)(CO)], the coordination environment around the Ru atom is slightly distorted octahedral. The Cl atoms are mutually trans to the dimethyl sulfoxide ligand and the imidazole carbene C atom, respectively. The carbonyl ligand is located trans to the pyridine N atom.
[1-tert-Butyl-3-(pyridin-2-ylmethyl-N)imidazol-2-ylidene-C 1 ]carbonyldichlorido(dimethyl sulfoxide-S)ruthenium(II) Y. Cheng, W.-Q. Hua and Y.-H. Zhou Comment N-Heterocyclic carbenes (NHCs) complexes have attracted increasing attention as they have been proven to act as efficient homogeneous catalyst (Hahn et al. 2006). Pyridine-functionalized bidentate carbene ligands have been frequently used as versatile ancillary ligands in organometallic complexes in recent years (Lee et al. 2007). A lot of bidentate pyridinefunctionalized NHC complexes have been prepared, some of which showed catalytic activities in reactions such as hydrosilylation of acetylenes, cyclization of acetylenic carboxylic acids, hydrogen transfer to ketones (Mas-Marza et al. 2005). However, few reports have been published on Ru complexes containing bidentate pyridine-functionalized NHC ligands (Kaufhold et al. 2008, Araki et al. 2008, Son et al. 2004, Poyatos et al. 2006. We have reported the synthesis and characterization of pyridine functionalized Ru(II)-NHC nitrosyl or carbonyl complexes and their catalytic activity in hydrogen transfer of ketones . Herein, we report a new pyridine functionalized Ru-NHC carbonyl complex with dimethyl sulfoxide.
The structure of the title complex shows that the coordination geometry around the ruthenium atom can be rationalized as a slightly distorted octahedron. Two chloride atoms occupy mutually trans to the dimethylsulfoxide and imidazole carbene carbon respectively. The CO group is located trans to the pyridine nitrogen ( Fig.1).

Experimental
A mixture of 3-tert-butyl-1-picolylimidazolium Bromide (1.0 mmol), silver oxide (1.0 mmol) and CH 2 Cl 2 (30 ml) was stirred at room temperature for 12 h, and was then filtered through Celite to remove unreacted silver oxide and insoluble residues. [Ru(CO) 2 Cl 2 ] n (1.0 mmol) was added to the pale yellow solution, stirred for 12 h at room temperature and then filtered through Celite to remove the silver halide. The products were chromatographed using silica gel. Elution with CH 2 Cl 2 : MeOH (40:1) afforded a pale yellow band that contained the trans-[(3-tert-butyl-1-picolylimidazol-2ylidene)biscolorodicarbonylruthenium], Removal of the volatiles under vacuum gave the products as pale yellow powders.

Exposured the saturated dimethyl sulfoxide solution of the trans-[(3-tert-butyl-1-picolylimidazol-2-
ylidene)biscolorodicarbonylruthenium] in air, yellow-rectangle crystals were obtained one month later, which were title complex confirmed by X-ray structure determination. It shows that dimethyl sulfoxide displaced one molecule of CO in previous compound, and the structure converted from trans to cis.

Refinement
The structures were solved by direct methods and refined on F 2 against all reflections by full-matrix least-squares methods with SHELXTL program. The hydrogen atoms in the compound were positioned geometrically (C-H = 0.93Å and O-H = 0.83 Å) and refined in the riding-model approximation, with U iso (H) set to 1.2U eq (O). All non-hydrogen atoms were refined supplementary materials sup-2 with anisotropic thermal parameters. The highest peak and deepest hole residual peak in the final difference Fourier map are located at 0.33Å and 1.30 Å, respectively, from atom Ru. Fig. 1. View of the title complex showing 30% probability ellipsoids. Hydrogen atoms are omitted for clarity.[symmetry codes: (i)'-x + 1/2, -y, z + 1/2' (ii)'-x, y + 1/2, -z + 1/2']