The structures of oxovanadium(V) triethanolaminate, 1, and oxovanadium(V) tri-2-propanolaminate, 2, have been determined. In each case the V(V) atom exhibits distorted trigonal bipyramidal coordination with the nitrogen atom and the oxo group in the axial positions. The distortion is observed because the vanadium atom is displaced out of the plane of the triethanolaminate oxygens in the direction of the doubly-bonded oxygen. Compound 1 crystallizes in the monoclinic space group P21 with a = 7.051 (2) A, b = 7.429(2) A, c = 7.980(2) A, @ = 93.46(3)O, V = 417.2(2) A', and 2 = 2. The discrete complex exhibits a V-N bond length of 2.276(1) A and an average VO(C) bond length of 1.794(3) A. Compound 2 crystallizes in the hexagonal space group P63 with a = 9.465(2) A, c = 7.493(2) A, V = 581.3(2) A, and 2 = 2. The discrete complex exhibits a V-N bond length of 2.297(15) A and a VO(C) bond length of 1.794 (5) A. The multinuclear solution NMR parameters of 1 and 2 were determined and compared to the parameters for aqueous complexes of vanadate and triethanolamine and vanadate and tri-2-propanolamine, respectively. The results and analyses of these systems lead to structural characterization of the aqueous complexes. 13C NMR and multinuclear NMR studies of related vanadium(V)-peptide complexes should assist in characterizing the coordination chemistry about the vanadium in complexes that resist structural analysis by X-ray diffraction.

A mononuclear vanadium(IV), a mononuclear vanadium(V), and a binuclear mixed valence vanadium(IV/V) complex with the ligand N-(2-hydroxyethyl)iminodiacetic acid (H(3)hida) have been structurally characterized. Crystal data for [VO(Hhida)(H(2)O)].CH(3)OH (1): orthorhombic; P2(1)2(1)2(1); a= 6.940(2), b = 9.745(3), c= 18.539(4) Å; Z = 4. Crystal 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) Å; beta = 102.53(2) degrees; Z = 4. Crystal data for (NH(4))[V(2)(O)(2)(&mgr;-O)(Hhida)(2)].H(2)O (3): monoclinic; C2/c; a = 18.880(2), b= 7.395(2), c = 16.010(2) Å; beta = 106.33(2) degrees; Z = 4. The mononuclear vanadium(IV) and vanadium(V) complexes are formed from the monoprotonated Hhida(2)(-) ligand, and their structural and magnetic characteristics are as expected for six-coordinate vanadium complexes. An interesting structural feature in these complexes is the fact that the two carboxylate moieties are 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) complexes are consistent with their structures. The vanadium(V) complex was previously characterized; in the current study structural characterization in the solid state is provided. X-ray crystallography and magnetic methods show that the mixed valence complex contains two indistinguishable vanadium atoms; the thermal ellipsoid of the bridging oxygen atom suggests a type III complex in the solid state. Magnetic methods show that the mixed valence complex contains a free electron. Characterization of aqueous solutions of the mixed valence complex by UV/vis and EPR spectroscopies suggests that the complex may be described as a type 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 less stable than the corresponding pmida and s-peida complexes of similar overall charge but very similar in stability to the nta and V(2)O(3)(3+) complexes with higher charges. Thus, there is the potential for designing stable mixed valence dimers.

excess chromic acid followed by sodium bicarbonate (ca. 4 g), and the suspension was allowed to stir 5 min. The suspension was filtered and the filter cake washed with acetone (2 X 20 mL). The bright yelloworange filtrate was evaporated in vacuo (rotary evaporator), and the yellow-orange residue was dissolved in methylene chloride (200 mL), washed with water, saturated NaHCOj, and brine, and dried over MgS04. The solvent was removed (rotary evaporator) to yield a bright yellow-orange solid. The solid was washed with ether (5 mL) and dried in vacuo to yield a bright yellow-orange solid: 0.045 g, 82% isolated yield;

No abstract