SOLUTION AND SOLID-STATE PROPERTIES OF [N-(2-HYDROXYETHYL)IMINODIACETATO]VANADIUM(IV), [N-(2-HYDROXYETHYL)IMINODIACETATO]VANADIUM(V), AND [N-(2-HYDROXYETHYL)IMINODIACETATO]VANADIUM(IV V) COMPLEXES/

A mononuclear vanadium(IV), a mononuclear vanadium(V), and a binuclear mixed valence vanadium(IV/V) complex with the ligand N-(2-hydroxyethy l)iminodiacetic acid (H(3)hida) have been structurally characterized. Crystal data for [VO(Hhida)(H2O)]. CH3OH (1): orthorhombic; P2(1)2(1)2 (1); a = 6.940(2), b = 9.745(3), c = 18.539(4) Angstrom; Z = 4. Crysta l data for Na[V(O)(2)(Hhida)(2)]. 4H(2)O (2): monoclinic; P2(1)/c; a = 6.333(2), b = 18.796(2), c = 11.5040(10) Angstrom; beta = 102.53(2)de grees; Z = 4. Crystal data for (NH4)[V-2(O)(2)(mu-O)(Hhida)(2)]. H2O ( 3): monoclinic; C2/c; a = 18.880(2), b = 7.395(2), c = 16.010(2) Angst rom; beta = 106.33(2)degrees; Z = 4. The mononuclear vanadium(IV) and vanadium(V) complexes are formed from the monoprotonated Hhida(2-) lig and, and their structural and magnetic characteristics are as expected for six-coordinate vanadium complexes. An interesting structural feat ure in these complexes is the fact that the two carboxylate moieties a re coordinated trans to one another, whereas the carboxylate moieties are coordinated in a cis fashion in previously characterized complexes . The aqueous solution properties of the vanadium(IV) and -(V) complex es are consistent with their structures. The vanadium(V) complex was p reviously characterized; in the current study structural characterizat ion in the solid state is provided. X-ray crystallography and magnetic methods show that the mixed valence complex contains two indistinguis hable vanadium atoms; the thermal ellipsoid of the bridging oxygen ato m suggests a type III complex in the solid state. Magnetic methods sho w that the mixed valence complex contains a free electron. Characteriz ation of aqueous solutions of the mixed valence complex by UV/vis and EPR spectroscopies suggests that the complex may be described as a typ e II complex. The Hhida(2-) complexes have some similarities, but also some significant differences, with complexes of related ligands, such as nitrilotriacetate (nta), N-(2-pyridylmethyl)iminodiacetate (pmida) , and N-(S)-[1-(2-pyridyl)ethyl]iminodiacetate (s-peida). Perhaps most importantly, the mixed valence Hhida(2-) complex is significantly les s stable than the corresponding pmida and s-peida complexes of similar overall charge but very similar in stability to the nta and V2O33+ co mplexes with higher charges. Thus, there is the potential for designin g stable mixed valence dimers.