31P and 195Pt solid-state NMR and DFT studies on platinum(i) and platinum(ii) complexes

Abstract

³¹P and ¹⁹⁵Pt solid state NMR spectra of anti-[(PHCy)ClPt(μ-PCy₂)₂Pt(PHCy)Cl] (3) and [(PHCy₂)Pt(μ-PCy₂)(κ²P,O-μ-POCy₂)Pt(PHCy₂)] (Pt–Pt) (4) were recorded under cross polarization/magic-angle spinning conditions (³¹P) or with the cross polarization/Carr–Purcell–Meiboom–Gill pulse sequence (¹⁹⁵Pt) and compared to the data obtained by relativistic DFT calculations of ³¹P and ¹⁹⁵Pt CS tensors and isotropic shielding at the ZORA spin–orbit level. A good agreement with the experimental results was found and it was possible to rationalize the chemical shift differences of ¹⁹⁵Pt and ³¹P nuclei between compounds 3 and 4 as mostly due to a change (in opposite directions for ¹⁹⁵Pt and ³¹P) of the principal component of the shielding tensor perpendicular to the molecular plane defined by the Pt and P atoms. Paramagnetic and spin–orbit terms were found to be the most important contributions to ¹⁹⁵Pt and ³¹P shielding.