Multinuclear Solid-State NMR and DFT Studies on Phosphanido-Bridged Diplatinum Complexes

Area of Science:

• Organometallic Chemistry
• Solid-State NMR Spectroscopy
• Computational Chemistry

Background:

• Platinum-phosphine complexes are crucial in catalysis and materials science.
• Understanding chemical shift tensors provides insights into electronic structure.
• The "ring effect" describes variations in chemical shifts in related compounds.

Purpose of the Study:

• To investigate the "ring effect" in platinum-phosphine complexes using multinuclear solid-state NMR.
• To elucidate the factors contributing to observed chemical shift variations.
• To validate experimental findings with Density Functional Theory (DFT) calculations.

Main Methods:

• Multinuclear ((31)P, (195)Pt, (19)F) solid-state NMR experiments.
• Cross-polarization/magic-angle-spinning (CP/MAS) and CP/Carr-Purcell Meiboom-Gill (CP/CPMG) pulse sequences.
• Density Functional Theory (DFT) calculations of chemical shift (CS) tensors.

Main Results:

• Analysis of (31)P and (195)Pt chemical shift tensors in complexes 1 and 2.
• Observed variations in isotropic chemical shifts attributed to changes in principal tensor components perpendicular to the Pt2P2 plane.
• DFT calculations confirmed experimental tensor orientations and identified paramagnetic and spin-orbit contributions as key factors for shielding differences.

Conclusions:

• The "ring effect" in these platinum complexes is primarily governed by structural and electronic factors perpendicular to the Pt2P2 plane.
• Experimental NMR data and DFT calculations provide a consistent understanding of the electronic structure and chemical shifts.
• This study enhances the understanding of structure-property relationships in organometallic platinum compounds.