# N‑Heterocyclic Carbene-Ag(I)-Phosphine Complexes: Comprehensive Synthesis, Characterization, and Bonding Analysis via Density Functional Theory

## TL;DR

This paper explores the synthesis and properties of silver complexes with phosphine ligands, revealing insights into their stability and bonding.

## Contribution

The study provides a comprehensive analysis of the synthesis and bonding in N-heterocyclic carbene-Ag(I)-phosphine complexes using DFT.

## Key findings

- The stability of [(IPr)Ag-PR3]+ complexes is lower than gold(I) analogs in solution.
- PCy3 and PPh2Py stabilize the cationic [(IPr)Ag(I)]+ fragment in methanolic solution.
- DFT analysis reveals electronic transitions and bonding contributions in the complexes.

## Abstract

The substitution
of a chloro ligand in (IPr)­Ag–Cl
with aliphatic
and aromatic phosphine ligands, PPh3, PCy3,
PPh2Py, dppf, dppm, and dppe, was investigated. Unlike
gold­(I) complexes, the heteroleptic complexes, [(IPr)­Ag-PR3]+, are less stable in the solution phase. The order of
mixing reactants, solvent type, and reaction time plays crucial roles
in obtaining the desired product. In a methanolic solution, the generated
[(IPr)­Ag­(I)]+ ions from (IPr)­Ag–Cl are less stable
compared with [(IPr)­Au­(I)]+ and only PCy3 and
PPh2Py stabilize this cationic fragment in solution. In
the single-crystal X-ray diffraction analysis of complexes 1 and 2, the Ag­(I) centers exhibited a linear geometry.
Other forms of silver­(I) complexes containing only phosphine ligands
were also formed in a solution containing the (IPr)­Ag–Cl precursor.
Computational analysis of the complexes using density functional methods
provided insights into the nature of electronic transitions, noncovalent
interactions, and fragmental bonding contributions.