Distortion of OPO bond angles in phosphorus monoanions: Ab initio studies

Abstract Results are reported from ab initio studies of phosphinate anion H 2 PO 2 − and phosphate anion, (HO) 2 PO 2 − and the distortion of these anions by the biochemically important metal cations, Mg ++ and Zn ++ . Ab initio results are reported from four basis sets for phosphinate ion and three basis sets for phosphate ion. We find that: 1) the results using the STO-3G ∗ basis set are in reasonable agreement with experimental data and with the calculation done with the large 6−31+ G ∗ basis set and second-order Moller-Plesset perturbation theory; 2) that phosphinate anion is an appropriate analog for studying the interactions of phosphate monoanion; 3) that the interaction with Mg ++ and Zn ++ is enough to cause the deformation previously hypothesized; 4) that correlations we have noted from experimental results are supported by the computational data; 5) that the OPO angle contracts significantly more on metal interactions than we predicted from our previous experimental studies using the one-bond, PH coupling constant; and 6) density matrix elements for interaction of the 3s orbital at phosphorous and 1s orbital at hydrogen correlate with one-bond, PH coupling constants.