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

## TL;DR

This paper explores how ligands affect the electronic structure and bonding in dinuclear platinum complexes, revealing how electron density shifts influence spin coupling and coordination.

## Contribution

The study introduces a combined ab initio and NLMO approach to quantify trans-influence effects in dinuclear Pt(III) complexes.

## Key findings

- Strong σ-donating ligands polarize the Pt–Pt bond, shifting electron density to the opposite platinum center.
- Bond polarization reduces 1JPtPt spin–spin coupling by diminishing spin density transmission through the Pt–Pt bond.
- Polarization induces a PtIV–PtII-like mixed-valence character, destabilizing axial water coordination.

## Abstract

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 PtIII complexes 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, and 1
J
PtPt spin–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 of 1
J
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 PtIV– PtII-like mixed-valence character.