Electron correlation and the lone pair effect in the phosphorous and arsenious acids: ab initio study of molecular structure and DFT calculations of 31P NMR spectra

The abnormal sensitivity of 31P NMR chemical-shift to hydrogen atom arrangement in tribasic acid P(OH)3 is found from a DFT study. The irregular proton localization in the pyramidal molecules P(OH)3 and As(OH)3 is suggested by experimental 31P NMR data and by ab initio calculation of both dibasic and tribasic phosphorous and arsenious acids. The electron correlations are shown to be responsible for the lower symmetry and the lone-pair effect in P(OH)3.