Solvent Effects on ¹⁹⁵Pt and ²⁰⁵Tl NMR Chemical Shifts of the Complexes [(NC)₅PtTl(CN)_n]ⁿ⁻ (n=0–3), and [(NC)₅PtTlPt(CN)₅]³⁻ Studied by Relativistic Density Functional Theory

Abstract

The 295Pt and 205Tl NMR chemical shifts of the complexes [(NC)5Pt-Tl(CN)n]n- n=0-3, and of the related system [(NC)5Pt--Tl--Pt(CN)5]3- have been computationally investigated. It is demonstrated that based on relativistically optimized geometries, by applying an explicit first solvation shell, an additional implicit solvation model to represent the bulk solvent effects (COSMO model), and a DFT exchange-correlation potential that was specifically designed for the treatment of response properties, that the experimentally observed metal chemical shifts can be calculated with satisfactory accuracy. The metal chemical shifts have been computed by means of a two-component relativistic density functional approach. The effects of electronic spin-orbit coupling were included in all NMR computations. The impact of the choice of the reference, which ideally should not affect the accuracy of the computed chemical shifts, is also demonstrated. Together with recent calculations by us of the Pt and Tl spin-spin coupling constants, all measured metal NMR parameters of these complexes are now computationally determined with sufficient accuracy in order to allow a detailed analysis of the experimental results. In particular, we show that interaction of the complexes with the solvent (water) must be an integral part of such an analysis.

Probing Isotope Shifts in 103Rh and 195Pt NMR Spectra with Density Functional Theory

“…A similar trend was found for the Pt-O bonds in Table S3 in the SI, where the Pt- 16 O bonds extend further in space than the corresponding Pt- 18 O bond. Note that the zero-point corrections to the eqilibrium PtCl distances are of the same order of magnitude as for the aquo complexes, 24 ca.…”

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

“…Detailed information can be found in previous papers. 27,28 Selected calculated bond lengths are listed in Table 1 and some of the optimized structures of the solvated complexes I-III and V are shown in Fig. 3.…”

“…The second section, below, describes the computational details and the computational models that have been applied in this study. The third section briefly reviews the results previously published 27,28 concerning the complexes I-V. The fourth section is devoted to the presentation of the NMR parameters computed for the complexes VI and VII.…”

“…27,28 As further summarized below, we have demonstrated the necessity of applying an explicit first solvation shell, an additional implicit solvation model to represent the bulk solvent effects and a DFT exchange-correlation (XC) potential that was specially designed for the treatment of response properties, in order to theoretically reproduce the experimental NMR properties with satisfactory accuracy. However, no detailed investigation of the relation between the electronic structure and the unusual NMR parameters of these complexes was carried out at this stage, except, in preliminary form, 13 for complex II.…”

The “Invisible” 13C NMR Chemical Shift of the Central Carbon Atom in [(Ph3PAu)6C]2+: A Theoretical Investigation

“…It has been shown that it provides a reasonable accuracy for NMR properties of heavy nuclei in "relativistic" systems, [23,46,[52][53][54][55][56][57][58][59] but not necessarily for light ligand nuclei. Therefore, NMR chemical shifts have additionally been computed by using the Perdew-Wang (PW91) [60] and the BP86 generalized gradient correction (GGA) density functionals in order to analyze the dependence of the results on the approximations in the density functional.…”