The 51V NMR Spectra of Some Oxo-, Peroxo-, Nitrosyl- and Hydroxylamidovanadium Complexes

The V NMR spectra are recorded for 3 dinuclear complexes {VO(ONR μ - O and 13 mononuclear vanadium (+ V) and (+III) chelate complexes of the general formula [VXYZ] , where X = O , NO ; Y = O , O , R NO ; and Z = picolinate-(pic), dipicolinate (dipic), nitrilo-tri(2-propanolate) , and o-phenanthroline (phen). Shielding of the V nucleus increases as O is replaced for NO-, and in the series (O + dipic) < (2 O + pic) < (R NO- + dipic) < (2 H NO + phen) < (2 H NO + pic); Et NO < H(Me)NO < H NO ; and (dinuclear complexes) C NO < Bz NO < Et NO These trends are explained on the basis of variations of molecular parameters correlated to electronic and steric factors associated with the ligands. Line widths of the 51V NMR signals are discussed in terms of influences originating from variations of the electric field gradient and the molecular correlation time