Syntheses and molecular structures of mononuclear ruthenium carbonyl complexes containing 2,1-naphthoquinone-2-oximato ligands

The reaction between [Ru3(CO)12] and 2,1-naphthoquinone-2-oxime or known as 2-nitroso-1-naphthol afforded two isomeric mononuclear ruthenium carbonyl complexes trans-[Ru(η2-OC10H6NO)2(CO)2] 1 and cis-[Ru(η2-OC10H6NO)2(CO)2] 2, in which the two bidentate 2-naphthoquinone-1-oximato ligands chelated on the ruthenium centre in different spacial orientation via the coordination of naphtholic oxygen and oxime nitrogen atoms. Both 1 and 2 adopt a cis-dicarbonyl configuration and the carbonyl groups can be replaced by the N-donor ligands in the presence of trimethylamine-N-oxide via the reaction intermediates, trans-[Ru(η2-OC10H6NO)2(CO)(NMe3)] 4 and cis-[Ru(η2-OC10H6NO)2(CO)(NMe3)] 3a respectively. Complexes 1, 3a and 4 have been fully characterised by spectroscopic methods and their molecular structures were established by X-ray crystallographic analyses.