The solvent (water) and dynamics effects on the electronic structure and nuclear magnetic resonance (NMR) indirect spin−spin coupling constant (j-coupling) and chemical shifts (delta) in a series of PtIII-PtIII bonded complexes are evaluated by means of Kohn−Sham (KS) Car−Parrinello molecular dynamics (CPMD) and relativistic hybrid KS NMR calculations with and without coordination to water. Solvation by water molecules has a sizeable impact on 1JPtPt and 195Pt chemical shift in Head-Head (HH) and Head-Tail (HT) of diaquo, dihalo and haloaquo alpha-pyridonato-bridged Pt binuclear complexes. J-coupling and delta are averaged over the CPMD trajectories using NMR calculations with hybrid KS NMR calculations reproduce the large magnitudes of the experimental values with the correct trends. Overall, 10 water molecules in addition to an implicit solvation model for mimicking the bulk are needed for calculated values with good accuracy. For example, spin-orbit relativistic j-coupling from scalar relativistic optimized geometry overestimates 1JPtPt by almost 124 %, while the spin-orbit relativistic averaged j-coupling over CPMD trajectories shows just 34 % of deviation in comparison with the experimental value in the HH diaquo complex. An analysis of 1JPtPt in terms of localized orbitals shows that the presence of solvent water molecules polarizes the axial ligand-Pt as well as Pt-Pt bonds, leading to a more well-balanced covalent interaction between the Pt centers. An increase of covalent character in the Pt-Pt bond directly affects the Fermi constant term, which overall describes the total value of the 1JPtPt.

NMR j-coupling constants and chemical shift of Pt−Pt bonded metal complexes in aqueous solution by ab initio molecular dynamics and localized orbital analysis

2019 Spring National Meeting

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