Group 11 m-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-Mes(2)C(6)H(3))(2)Fe and (2,6-Xyl(2)C(6)H(3))(2)Fe (Mes = 2,4,6-Me3C6H2; Xyl = 2,6-Me2C6H3). [2,6-Mes(2)C(6)H(3)M] 2 (1, M = Cu; 2, M = Ag; 6, M = Au) and [2,6-Xyl(2)C(6)H(3)M] 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-Mes(2)C(6)H(3))Au center dot SMe2 (5). NMR spectroscopic measurements, including diffusion-ordered spectroscopy, suggest that 1-4 remain dimeric in a benzene-d(6) 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.