Electronic effects of the substituent group in 8-quinolinolato ligand on geometrical isomerism for nitrosylruthenium(II) complexes

The reaction of hydrous nitrosylruthenium trichloride with 2-chloro-8-quino linol (H2cqn) or 2-methyl-8-quinolinol (H2mqn) in ethyl alcohol, 50 vol.% e thyl alcohol-water, water or acetic acid solution adjusted to pH 5.5 and th e reaction of two kinds of geometrical isomers, cis-1 and cis-2[RuX(qn)(2)N O] (X = acetate or Cl; Hqn = H2cqn or H2mqn), with chloride or acetate ion in ethyl alcohol were examined in order to compare the effect of the chloro and methyl groups of the 2-position in 8-quinolinolato ligands on geometri cal isomerism for nitrosylruthenium(II) complexes. The thermal and photoind uced reactions for the 2cqn complexes were also compared with those for the 2mqn complexes. The differences in the substituent in the 8-quinolinolato ligand and of the solvents used for the reactions were related to geometric al isomerism of the products. In general, the 2cqn complexes especially fav or the cis-2 geometry, while the 2mqn complexes favor the cis-1 and trans g eometries. The structures of cis-1[RuCl(2cqn)(2)NO], cis-2[RuCl(2cqn)(2)NO] and trans-[Ru(OEt)(2mqn)(2)NO] (OEt = ethanolate ion) were determined by X -ray diffraction. (C) 2000 Elsevier Science S.A. All rights reserved.