Group 11 <i>m</i>‑Terphenyl Complexes Featuring Metallophilic Interactions

A series of group 11 m-terphenyl complexes have been synthesized via a metathesis reaction from the iron­(II) complexes (2,6-Mes2C6H3)2Fe and (2,6-Xyl2C6H3)2Fe (Mes = 2,4,6-Me3C6H2; Xyl = 2,6-Me2C6H3). [2,6-Mes2C6H3M]2 (1, M = Cu; 2, M = Ag; 6, M = Au) and [2,6-Xyl2C6H3M]2 (3, M = Cu; 4, M = Ag) are dimeric in the solid state, although different geometries are observed depending on the ligand. These complexes feature short metal–metal distances in the expected range for metallophilic interactions. While 1–4 are readily isolated using this metathetical route, the gold complex 6 is unstable in solution at ambient temperatures and has only been obtained in low yield from the decomposition of (2,6-Mes2C6H3)­Au·SMe2 (5). NMR spectroscopic measurements, including diffusion-ordered spectroscopy, suggest that 1–4 remain dimeric in a benzene-d6 solution. The metal–metal interactions have been examined computationally using the Quantum Theory of Atoms in Molecules and by an energy decomposition analysis employing natural orbitals for chemical valence.