Formation of dicyano ruthenium(II) complex mediated by triethylamine via deprotonation of hydrazonochroman-2,4-dione

New ruthenium(II) complex containing cyanide anions has been isolated from the hydrazonochromandione ligand 3-(2-(4-chlorophenyl)hydrazono)chroman-2,4-dione in the presence of acetonitrile along with triethylamine from Ru(III) salt. This method is a one-pot synthetic approach for preparing dicyano Ru(II) complex. Using physicochemical and spectral techniques, the synthesized compound [Ru(CN)₂L₂]·2Et₃N⁺H was structurally described. The monoanionic bidentate character of the hydrazone ligand and coordination through carbonyl oxygen and deprotonated hydrazonochroman-2,4-dione nitrogen atom were revealed by single crystal X-ray diffraction investigation of the Ru(II) complex. Ru(II) complex is a member of the P21/n space group and monoclinic system. Ru(II) chelate rings were stabilized by intermolecular hydrogen bonds and π–π stacking interactions between ligands and triethylammonium molecules. A single phase with rod-like morphologies is imaged by SEM. The quasi-reversible single electron transfer property is exhibited by the Ru(II) complex.

Using a 2:1 ligand-metal ratio, a Ru(II) complex with low spin was isolated.