Synthesis and characterisation of new molybdenum – oxo complexes containing diphenylphosphinylacetic acid and 2-(tert-butylsulphoxide)phenyldiphenylphosphine oxide as bidentate ligands

Reaction of the ligands diphenylphosphinylacetic acid Ph2P(O)CH2COOH (1) and 2-(tert-butylthio)phenyldiphenylphosphine oxide Ph2P(O)C6H4tBuS (2) with “MoO2Cl2”, resulted in two complexes MoO2Cl2Ph2P(O)CH2COOH (3) and MoO2Cl2Ph2P(O)C6H4tBuS(O) (4). Complexes 3 and 4 were isolated and analysed by 1H NMR, 31P NMR and X-ray crystallography. Complex 3 crystallised with a molecule of the free ligand in a 1:1 ratio (3·1) and complex 4 crystallised with molecules of the solvent CH2Cl2 within the unit cell in a 2:1 ratio (4·0.5CH2Cl2). Tetrameric arrangements comprised of hydrogen bonds were observed in complexes 1 and 3. Complex 4 exhibited a seven-membered ring structure owing to the oxidation of the sulphide in 2 to sulphoxide and coordination of this ligand via the oxygen atoms to the molybdenum atom.