A chloro(2-pyridinecarboxaldehyde)(2,2':6',2"-terpyridine)ruthenium(II) complex

The aldehyde moiety in the title complex, chloro(2-pyridinecarboxaldehyde-N,O)(2,2':6',2"-terpyridine-kappa(3)N)ruthenium(II)-chloro(2-pyridinecarboxylic acid-N,O)(2,2':6',2"-terpyridine-kappa(3)N)ruthenium(II)-perchlorate-chloroform-water (1.8/0.2/2/1/1), [RuCl(C6H5NO)(C15H11N3)](1.8)[RuCl(C6H5NO2)(C15H11N3)](0.2)(ClO4)2-CHCl3-H2O, is a structural model of substrate coordination to a transfer hydrogenation catalyst. The title complex features two independent Ru(II) complex cations that display very similar distorted octahedral coordination provided by the three N atoms of the 2,2':6',2"-terpyridine ligand, the N and O atoms of the 2-pyridinecarboxaldehyde (pyCHO) ligand and a chloride ligand. One of the cation sites is disordered such that the aldehyde group is replaced by a 20 (1)% contribution from a carboxylic acid group (aldehyde H replaced by carboxyl O-H). Notable dimensions in the non-disordered complex cation are Ru-N 2.034 (2) A and Ru-O 2.079 (2) A to the pyCHO ligand and O-C 1.239 (4) A for the pyCHO carbonyl group.