The Effect of Trigonal Bipyramidal Distortion of Pentacoordinate V(IV)O(2+) Species on their Structural, Electronic and Spectroscopic Parameters

The effect of trigonal bipyramidal distortion of pentacoordinate (VO2+)-O-IV species on their structural, electronic and spectroscopic parameters was calculated by DFT methods. In particular i) the bis chelated species with [VO(LH-1)(2)](2-) stoichiometry formed in water with five alpha-hydroxycarboxylic acid ligands [glycolic (glycH), lactic (lactH), 2-hydroxyisobutyric (2-hibH), 2-ethyl-2-hydroxybutyric (2-ehbH) and 2-isopropyl-2-hydroxybutyric (2-iPrhbH) acids], ii) the bis complexes [VOL2] formed in the solid state with three salicylaldimine derivatives [N-methylsalicylaldimine (MeSalH), N-isopropyl-o-methylsalicylaldimine (iPr-MeSalH) and N-methyl-o-tert-butyl-p-methylsalicylaldimine (tBu-MeSalH)] and iii) the solid bis chelated compounds with composition [VOL2] formed with aminophenolate ligands {2-[(dimethylamino)methyl]-phenol (NMe(2)phenH), 2-(piperid-1-ylmethyl)-4-methylphenol (Pip-4MephenH), 2-[(dimethylamino) methyl]-6-tert-butylphenol (NMe2-tBuphenH)} were examined. The variation of the structural [bond lengths, axial and equatorial angles, value of Delta E(solv), molecular orbital composition and electronic structure], EPR (vertical bar A(x) - A(y)vertical bar, vertical bar A(iso)vertical bar, vertical bar A(z)vertical bar and vertical bar g(x) - g(y)vertical bar), UV/Vis (Delta lambda = lambda(2) - lambda(3) and lambda(1)), IR (nu(V=O)) and electron spin echo envelope modulation (ESEEM) spectroscopic parameters (vertical bar A(iso)(N)vertical bar, C-Q and eta) as a function of the structural index of trigonality, tau = (beta - a)/60 (where beta and a are the angles subtended by vanadium between the two axial and equatorial donors), is illustrated.