Synthesis, characterisation and thermal studies of ruthenium(II) carbonyl complexes of functionalised tripodal phosphine chalcogen donor ligands, [CH 3C(CH 2P(X)Ph 2) 3], where X = Se, S, O

The polymeric ruthenium(II) carbonyl complex, [Ru(CO) 2Cl 2] n reacts with 1,1,1-tris-(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH 3C(CH 2P(X)Ph 2) 3], where X = Se( a), S( b) and O( c) in 1:1 (metal:ligand) molar ratio to afford hexa-coordinated complexes of the type η 2-(X,X)-[Ru(CO) 2Cl 2P 3X 3] ( 1a– c). The complexes 1a– c exhibit two equally intense ν(CO) bands in the range 1979–2060 cm −1 indicating cis-disposition of the two terminal carbonyl groups. The values of ν(CO) frequencies containing different ligands, in general, follow the order: P 3O 3 > P 3S 3 > P 3Se 3 which may be explained in terms of ‘Soft–Hard’ (Ru(II)–O) and ‘Soft–Soft’ (Ru(II)–S/Se) interactions. The complexes have been characterized by elemental analyses, mass, 1H, 31P, 77Se and 13C NMR spectroscopy. The thermal stability of the complexes has also been studied.