Novel ruthenium nitrosyl complexes formed by nitrosating the tris(violurato)- and tris(1,3-dimethylviolurato)-ruthenate(II) anions

Abstract

The salt Na₂[Ru(NO)(NO₂)₄(OH)] reacts with barbituric acid in water to give Na[Ru(H₂va)₃](H₂va^–= bidentate violurate), and with 1,3-dimethylbarbituric acid to give Na[Ru(dmva)₃](dmva^–= bidentate 1,3-dimethylviolurate). The complexes react with Na[NO₂] in acidic aqueous solutions to afford a series of novel diamagnetic nitrosylruthenium complexes of the general type cis-[Ru(L–L)₂(NO)X](L–L = bidentate H₂va^– or dmva^–; X^–= Cl^–, Br^–, or unidentate H₂va^– or dmva^–). In water, acetomtrile, or dimethyl sulphoxide. the complexes cis-[Ru(L–;L)₃(NO)] release the co-ordinated nitrosyl lirgand owing to the intramolecular transformation: cis-[Ru(L–L)₂(NO)(unidentate L–L)]→[Ru(L–L)₂(bidentate L–L)]^–+[NO]⁺. On the basis of the i.r. and ¹H n.m.r. spectra, the most probable structures of the complexes are given and the high electrophilicity of co-ordinated NO is shown to result from the strong π-backbonding properties of the bidentate violurate ligands.