(51)V solid-state NMR and density functional theory studies of eight-coordinate non-oxo vanadium complexes: oxidized amavadin.

Using (51)V magic angle spinning solid-state NMR spectroscopy and density functional theory calculations we have characterized the chemical shift and quadrupolar coupling parameters for two eight-coordinate vanadium complexes, [PPh(4)][V(v)(HIDPA)(2)] and [PPh(4)][V(v)(HIDA)(2)]; HIDPA = 2,2'-(hydroxyimino)dipropionate and HIDA = 2,2'-(hydroxyimino)diacetate. The coordination geometry under examination is the less common non-oxo eight coordinate distorted dodecahedral geometry that has not been previously investigated by solid-state NMR spectroscopy. Both complexes were isolated by oxidizing their reduced forms: [V(iv)(HIDPA)(2)](2-) and [V(iv)(HIDA)(2)](2-).

Chloro-substituted dipicolinate vanadium complexes: synthesis, solution, solid-state, and insulin-enhancing properties.

Three vanadium complexes of chlorodipicolinic acid (4-chloro-2,6-dipicolinic acid) in oxidation states III, IV, and V were prepared and their properties characterized across the oxidation states. In addition, the series of hydroxylamido, methylhydroxylamido, dimethylhydroxylamido, and diethylhydroxylamido complexes were prepared from the chlorodipicolinato dioxovanadium(V) complex. The vanadium(V) compounds were characterized in solution by (51)V and (1)H NMR and in the solid-state by X-ray diffraction and (51)V NMR.

51V solid-state NMR and density functional theory studies of vanadium environments in V(V)O2 dipicolinic acid complexes.

(51)V solid-state NMR and density functional theory (DFT) investigations are reported for a series of pentacoordinate dioxovanadium(V)-dipicolinate [V(V)O(2)-dipicolinate] and heptacoordinate aquahydroxylamidooxovanadium(V)-dipicolinate [V(V)O-dipicolinate] complexes. These compounds are of interest because of their potency as phosphatase inhibitors as well as their insulin enhancing properties and potential for the treatment of diabetes. Experimental solid-state NMR results show that the electric field gradient tensors in the V(V)O(2)-dipicolinate derivatives are affected significantly by substitution on the dipicolinate ring and range from 5.

Investigating the vanadium environments in hydroxylamido V(V) dipicolinate complexes using 51V NMR spectroscopy and density functional theory.

Using (51)V magic angle spinning solid-state NMR, SSNMR, spectroscopy and quantum chemical DFT calculations we have characterized the chemical shift and quadrupolar coupling parameters of a series of eight hydroxylamido vanadium(V) dipicolinate complexes of the general formula VO(dipic)(ONR1R2)(H2O) where R1 and R2 can be H, CH3, or CH2CH3. This class of vanadium compounds was chosen for investigation because of their seven-coordinate vanadium atom, a geometry for which there is limited (51)V SSNMR data. Furthermore, a systematic series of compounds with different electronic properties are available and allows for the effects of ligand substitution on the NMR parameters to be studied.