Synthesis and structures of ruthenium di- and tricarbonyl complexes derived from 4,5-diazafluoren-9-one

Abstract

Carbon monoxide (CO) has recently been shown to impart beneficial effects in mammalian physiology and considerable research attention is now being directed toward metal–carbonyl complexes as a means of delivering CO to biological targets. Two ruthenium carbonyl complexes, namelytrans-dicarbonyldichlorido(4,5-diazafluoren-9-one-κ2N,N′)ruthenium(II), [RuCl2(C11H6N2O)(CO)2], (1), andfac-tricarbonyldichlorido(4,5-diazafluoren-9-one-κN)ruthenium(II), [RuCl2(C11H6N2O)(CO)3], (2), have been isolated and structurally characterized. In the case of complex (1), thetrans-directing effect of the CO ligands allows bidentate coordination of the 4,5-diazafluoren-9-one (dafo) ligand despite a larger bite distance between the N-donor atoms. In complex (2), thecisdisposition of two chloride ligands restricts the ability of the dafo molecule to bind ruthenium in a bidentate fashion. Both complexes exhibit well defined1H NMR spectra confirming the diamagnetic ground state of RuIIand display a strong absorption band around 300 nm in the UV.