The synthesis of several dinuclear @-oxo)bis@-carboxylato or diphenylphosphato) divanadium(II1) complexes, [V20(02CR)2Lz] (where L = HB(pz)3-and R = CH3 (I), C6H5 (11), C2H5 (111), and H (IV), or L = HB(3,5-Mezpz)3-and R = CH3 (V)) and [VZ~(~~P(OC~H~)Z)~(HB(~Z)~)~] (X), are described. X-ray crystallographic anal sis of I11 and X gave the following parameters: 111, C~~& Z B~N I~O~V~, P21/n, a = 13.406(3) A, b = 15.313-(3) 1, c = 22.217(4) A, ,8 = 106.75(3)", Z = 4, V = 4367(2) A3; X, C U H~~B~N I~O~P~V~, P21/n, a = 11.944(4) A, b = 20.091(7) A, c = 21.729(16) A, p = 94.38(4)", Z = 4, V = 5199(4) A3. Protonation of the oxo-bridged species with either HC104 or HS03CF3 causes a rapid color change from deep green to pale red and results in the crystallization of the hydroxo-bridged species [VZ(OH)(O~CR)~(HB(PZ)~)~](X) (where R = CH3 and X = C104-(VI) or R = C2H5 (VQ, C6H5 (W), and H (W, and X = CFsS03-) and [ V~( O H ) ( O~P (~~H~>~)~( H B ( P Z )~)~I ( C S 0 3 ) (XI). Crystallographic parameters are as follows: VIIb, C29H39B2F3N1209SV2, P212121. a = 12.309(3) A, b = 16.197(2) A, c = 20.232(2) A, Z = 4, V = 4033.9(9) A3; XI, C56.5H64.5B2F3N120,4,5P2sV2, Pi, a = 12.113-(2) A, b = 14.938(3) A, c = 20.052(4) A, a = 72.88(3)", ,8 = 76.73(3)", y = 87.15(3)", Z = 4, V = 3374.3 (11) A3. In contrast to well-studied oxo-bridged Fe(III) complexes, W-visible, paramagnetic NMR, resonance Raman, and magnetic susceptibility on these V(III) complexes reveal electronic and magnetostructural correlations dependent on the V-0-V angle. Such correlations may be useful in assigning structures to complex biosystems containing the [V@-0)Vl4+ core.in the biochemistry of tunicates. Certain species of tunicates have long been known to concentrate vanadium, primarily as V(III), in their blood cell^.^.^ Upon cell lysis ascidian blood rapidly tums bright red, a characteristic first recognized by H e n~e .~ Although there is no structural data available on the chromophore in "Henze's solution", model compound studies and UV-visible spectroscopic measurements carried out in solution are all consistent with the formation of an oxo-bridged divanadium(III) core.8-10 While X-ray crystallography provides the most definitive and precise structural information on large biomolecules, its application is frequently beset with the difficulties of growing single crystals. In contrast, complementary spectroscopic probes of structure do not suffer as much from this limitation and are readily applicable to aqueous solutions, the ubiquitous biological medium. Hence one of the main goals of our research program is to provide spectro-and magnetostructural relationships for oxo-bridged vanadium dimers. By establishing relationships between the structures of small well-defined molecules, as determined by X-ray crystallography, and spectral and magnetic properties, such as UV-visible and resonance Raman spectroscopies as well as magnetic exchange coupling constants, it may be possible to extract detailed structural data from complex biosystems such as tunicate blood....

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Plasmid DNA is cleaved by dimeric 0x0-bridged vanadium(II1) complexes without exogenous oxidants or reductants.

complete listings of bond lengths and angles, the cyclic voltammogram of 1, 2, 3, and 4 (15 pages); listings of observed and calculated structure factors (15 pages). Ordering information is given on any current masthead page.

The synthesis and characterization of four dinuclear V(IV) complexes are described:  1, [LVO(μ-(Ph)2PO2)LVO]; 2, [LVO(μ-(Ph)HPO2)2LVO]; 3, [LVO(μ-OH)2LVO]; and 4, [LVO(μ-OH)(μ-OAc)LVO] (where L = hydrotris(pyrazolyl)borate). X-ray crystal structural analysis of 1−4 gave the following parameters:  1, C46H46B2N14O6P2V2, P1̄, a = 12.249(2) Å, b = 13.951(3) Å, c = 16.391(3) Å, α = 93.95(3)°, β = 100.53(3)°, γ = 110.01(3)°, Z = 2; 2, C47H48B2N19O9P3V3, P1̄, a = 9.927(2) Å, b = 12.307(2) Å, c = 24.878(3) Å, α = 98.12(1)°, β = 100.79(1)°, γ = 91.05(1)°, Z = 2; 3, C22H28B2N14O4V2, Pbca, a = 10.698(1) Å, b = 15.414(3) Å, c = 17.865(3) Å, Z = 4; 4, C24H24B2N12O5V2, C2/c, a = 34.252(4) Å, b = 14.623(2) Å, c = 15.387(2) Å, β = 102.32(1)°, Z = 8. Magnetic measurements indicate that all the compounds except 4 are moderately antiferromagnetically coupled. A rationalization for the magnetic behavior of these and other complexes of this type based on a direct overlap model modulated by the conformation of the eight-membered V(μ-OXO)2V ring is proposed.