[(HB(pz)3(µ-CH3CH2CO2)V]2OH.(CH2)4O

A supported µ-hydroxo bis(µ-propionato) divanadium(III) complex





The presence of two cobridging propionato ligands forces a bent V-OH-V geometry with a 123° bridge angle. This angle is about 10° smaller than found in the corresponding unprotonated oxo-bridged complex, but about the same as that typically found in other M(III)-O(H)-M(III) complexes with carboxylate bridging ligands. Protonation of the oxo-bridge apparently forces sp2 hybridization on the bridging oxygen producing ~120° bond angles about the oxygen. A pronounced lengthening (~.20 A) of the V-O bonds relative to the oxo-bridged complex also occurs to give lengths expected of V-O single bonds. Dramatic changes in physical properties also accompany these structural changes. The intense LMCT transitions that give a dark green color to the oxo-bridged complex are lost on protonation (due to the bond length increase) so that only weak d-d transitions and a faint red color are observed for the hydroxo bridged complex. The strong ferromagnetic coupling between V(III) ions in the oxo-bridged complex switches to moderate antiferromagnetic coupling in the hydroxo-bridged complex, possibly because of the decrease in bridge bond angle.

As with the oxo-bridged complex, the structure of the hydroxo-bridged dimer also contains solvate molecules, but of THF instead of acetonitrile. In contrast to the former structure, in which nonspecific "packing forces" are responsible for inclusion of the solvent, the THF oxygen forms a short direct hydrogen bond to the bridge proton. Crystals of the hydroxo-bridged complex grown from diethyl ether and acetonitrile also show similar interactions between dimeric complex and included solvent.

Literature reference: Bond, M. R., Czernuszewicz, R. S., Dave, B. C., Mohan, M., Verastgue, R., and Carrano, C. J. "Spectroscopic and Magnetostructural Correlations in Oxo-Bridged Dinuclear Vanadium(III) Complexes of Potential Biological Significance" Inorg. Chem. 1995, 34, 5857-5869.

Companion Structure: [(HB(pz)3(mu-CH3CH2CO2)V]2O.4CH3CN

Structure Determination Files by FTP

Download X-ray Data Set (ruben4.hkl)

Download X-ray Data Collection Parameters (ruben4.p4p)

Download Final Refinement Results (ruben4.res)

Last changed December 7, 1996

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