Accurate prediction of Pt-195-NMR chemical shifts for hydrolysis products of [PtCl6](2-) in acidic and alkaline aqueous solutions by non-relativistic DFT computational protocols

摘要

The Pt-195-NMR chemical shifts of all possible hydrolysis products of [PtCl6](2-) in acidic and alkaline aqueous solutions are calculated employing simple non-relativistic density functional theory computational protocols. Particularly, the GIAO-PBE0/SARC-ZORA(Pt) U 6-31 + G(d)(E) computational protocol augmented with the universal continuum solvation model (SMD) performs the best for calculation of the Pt-195-NMR chemical shifts of the Pt(IV) complexes existing in acidic and alkaline aqueous solutions of [PtCl6](2-). Excellent linear plots of delta(calcd)(Pt-195) chemical shifts versus delta(exptl)(Pt-195) chemical shifts and delta(calcd)(Pt-195) versus the natural atomic charge Q(Pt) are obtained. Very small changes in the Pt-Cl and Pt-O bond distances of the octahedral [PtCl6](2-), [Pt(OH)(6)](2-), and [Pt(OH2)(6)](4+) complexes have significant influence on the computed sigma(iso) Pt-195 magnetic shielding tensor elements of the anionic [PtCl6](2-) and the computed delta Pt-195 chemical shifts of [Pt(OH)(6)](2-) and [Pt(OH2)(6)](4+). An increase of the Pt-Cl and Pt-O bond distances by 0.001 angstrom (1 m angstrom ) is accompanied by a downfield shift increment of 17.0, 19.4, and 37.6 ppm m angstrom(-1), respectively. Counter-anion effects in the case of the highly positive charged complexes drastically improve the accuracy of the calculated Pt-195 chemical shifts providing values very close to the experimental ones.