Isolation, structural and spectroscopic investigations of complexes with tridentate [O,P,O] and [O,O,O] donor ligands

A phosphorus-containing potentially tridentate ligand bis(3,5-di-tert-butyl -2-hydroxyphenyl)phenylphosphine H2L, 1, was prepared. 1 reacts directly in solution with aerial oxygen or hydrogen peroxide to form bis(3,5-di-tert-b utyl-2-hydroxyphenyl)phenylphosphine oxide H2LO, 2. It yields complexes [Ni -II(HL)(2)] 3, [Co-III(OH2)(HL)(L)] 4, [(RhCl)-Cl-III(H2L)(L)] 5, and [Rh-I II(HL)(L)(H2O)] 6 characterized by various physical techniques, including I R, MS, UV-vis, H-1 and P-31-{H-1} NMR and electrochemical methods. The crys tal structures of 3, 4 and 5 show tridentate [O,P,O] and bidentate [O,P,OH] coordination of deprotonated 1 and the coordination geometry of the metal centre. The structure of 2 reveals strong hydrogen bonding between the phen olic hydroxyl groups and the O=P group in the solid state. That the ligand 2 produces a weak ligand field providing tridentate [O,O,O] coordination si tes has been evidenced by the structure and paramagnetism of [Co-2(II)(LO)( 2)(C2H5OH)(3)] 7.