Regulation of Geometry around the Ruthenium Center of Bis(2-pyridinecarboxylato) Complexes by the Nitrosyl Moiety: Syntheses, Structures, and Theoretical Studies

cis-[Ru(NO)Cl(pyca)2] (pyca = 2-pyridinecarboxylato), in which the two pyridyl nitrogen atoms of the two pyca ligands coordinate at the trans position to each other and the two carboxylic oxygen atoms at the trans position to the nitrosyl ligand and the chloro ligand, respectively (type I shown as in Chart 1), reacted with NaOCH3 to generate cis-[Ru(NO)(OCH3)(pyca)2] (type I). The geometry of this complex was confirmed to be the same as the starting complex by X-ray crystallography: C13.5H13N3O6.5Ru; monoclinic, P21/n; a = 8.120(1), b = 16.650(1), c = 11.510(1) (angstrom);(beta) = 99.07(1)°; V = 1536.7(2) (angstrom)^3; Z = 4. The cis-trans geometrical change reaction occurred in the reactions of cis-[Ru(NO)(OCH3)(pyca)2] (type I) in water and alcohol (ROH, R = CH3, C2H5) to form [{trans-Ru(NO)(pyca)2}2(H3O2)]+ (type V) and trans-[Ru(NO)(OR)(pyca)2] (type V).