Synthesis and aqueous solution properties of multinuclear oxo-bridged vanadium(IV/V) complexes

Reaction of the multifunctional phenolic ligands 2,5-bisN,N-bis(carboxymethyl)aminomethyl]hydroquinone (H6cahq), 2,2'-bisN,N-bis(carboxymethyl)aminomethyl]-4,4'-isopropylidenediphen ol(H6capd),2,2',2'-trisN,N-bis(carboxymethyl)aminomethyl]-1,1 ,1-tris(4-hydroxyphenyl)ethane (H9catp) and the monofunctional 2-N,N-bis(carboxymethyl)aminomethyl]-4-carboxyphenol (H3cacp), with VOSO4 and NaVO3 affords the oxo-bridged mixed-valence vanadium(IV/V) Na6(VO)4(mu-O)2(mu-cahq)2] x Na2SO4 x 20H2O (1), HnNa(3-n)(VO)2(mu-O)(mu-cacp)2] (2), HnNa(3-n)(VO)4(mu-O)2(mu-capd)2] (3), HnNa(9-n)(VO)6(mu-O)3(mu3-catp)2] (4). In addition to the synthesis, we report the infrared, magnetic, optical and electrochemical properties of these complexes. The hydrolytic stability at different pH values was also investigated using visible spectroscopy.