Experimental and First-Principles NMR Analysis of Pt(II) Complexes WithO,O′-Dialkyldithiophosphate Ligands

Abstract

Polycrystalline bis(dialkyldithiophosphato)Pt(II) complexes of the form Pt{S 2 P(OR) 2 } 2 (R = ethyl, iso-propyl, iso-butyl, sec-butyl or cyclo-hexyl group) were studied using solid-state 31 P and 195 Pt NMR spectroscopy to determine the influence of the alkyl substituents to the structure of the central chromophore. The results for 195 Pt CS tensors demonstrated that differences in alkyl substitutes of dialkyldithiophosphate ligands in the complexes studied have an insignificant effect on the distorted-square form structure of the central PtS 4 core. However, the principal values of 31 P chemical shift tensors in dialkyldithiophosphate ligands do differ significantly, which may be used to distinguish between different complexes. Relativistic effects (both scalar and spin-orbit) were shown to be important for the NMR parameters of both 31 P and 195 Pt nuclei. The effects due to the periodic crystal lattice were found to be non-negligible, especially for the CS tensor of the heavy-metal 195 Pt isotope. A particular correction model for incorporating lattice effects was adopted to avoid a severe deterioration of the anisotropic parameters due to the high requirements posed on the pseudopotential quality in such calculations. It seems that the pseudopotentials available in standard software may be inadequate for periodic calculations of anisotropic NMR parameters.

Tuning Nuclear Quadrupole Resonance: A Novel Approach for the Design of Frequency-Selective MRI Contrast Agents

“…In addition to the scalar relativistic (SR) effects, the influence of relativistic spinorbit coupling (SO) needs to be taken into account in the heavy element magnetic resonance parameters [55,57,58]. While combining relativistic theory with more elaborate electron correlation treatment with hybrid functionals of the density functional theory (DFT) is currently not feasible for periodic solids, we follow closely the approach of Roukala et al for the nuclear shielding tensor of 195 Pt in molecular solids [59]. The following nomenclature is introduced to describe the calculation inputs: DFT Functional_Relativistic level_Basis Set, e.g., PBE_SO-ZORA_TZ2P, i.e., at spinorbit coupling zeroth order regular approximation (SO-ZORA) theory using the PBE DFT functional and TZ2P basis set, and it will be used to discuss the results.…”

Structure and bonding in rhodium coordination compounds: a 103Rh solid-state NMR and relativistic DFT study

“…SSNMR can be applied to investigate 103 Rh directly, as well as an assortment of nuclides in the bonded ligands. [15][16][17][18][19][20][21][22] The measurement of the relevant NMR interaction tensors (e.g., 103 Rh chemical shi tensors) and their calculation provides details about metal-ligand interactions, leading to a deeper understanding of structure-functionproperty relationships. However, both 103 Rh SSNMR measurements and DFT calculations of 103 Rh magnetic shielding tensors present considerable challenges.…”