Trans-Influence in Dinuclear Pt(III) Complexes: Electronic Structure, σ-Donation, and Pt–Pt Spin–Spin Coupling

This study investigates the trans influence in dinuclear platinum(III) complexes using a combined approach of ab initio molecular dynamics and natural localized molecular orbital (NLMO) analysis. Focusing on pivalamidate-bridged Pt^IIIcomplexes with axial ligands of varying σ-donation strength, it is quantified how ligand–metal interactions propagate through the Pt–Pt bond, and how they affect bond polarization, axial water coordination, and¹J_PtPtspin–spin coupling constants. NLMO analysis reveals quantitatively that strong σ-donating ligands polarize the Pt–Pt bond, shifting the electron density toward the opposite platinum center. The polarization mechanism is identified as the primary reason for the observed reduction of¹J_PtPt, because the bond polarization diminishes the transmission of the nuclear magnetic spin-induced electron spin density through the Pt–Pt bond. Additionally, the destabilization of axial water coordination at the opposite Pt site can be rationalized through a polarization-induced Pt^IV– Pt^II-like mixed-valence character.