Nuclear Quadrupole Perturbations in V NMR Spectra of Oxovanadium(+V) Complexes

Nuclear electric quadrupole coupling constants e2qQ/h have been obtained b y evaluation o f quadrupole perturbations in 5 1 V N M R spectra of various vanadyl esters and esterchlorides of the general formula V O C l 3 _ „ ( O R ) n («, = 0 3 ; = Me, Prra, Pr*, B u » and Bu«). e2qQlh values have been calculated from (i) 2nd. order quadrupole splittings of the 5 1 V N M R signals in pseudopolycrastalline samples, (ii) 1st. order quadrupole splittings in nematic liquid crystals and (iii) line widths A v\ti of the 5 1 V and 35C1 N M R signals in the liquid isotropic state and e2qQ/h(35CI) obtained by pure N Q R measurements. The influences of the asymmetry parameter r) and the orientation of the crystallites in powder spectra are considered, and temperature and concentration effects upon Zbi/2 and 5 1 V shielding (isotropic phases) and the ordering factor (mesophases) are discussed.