New Structural Motifs Resulting from Internal Constraints in Chelating Bis(NHC) Ligands: A Dinuclear Ruthenium(II) Complex Featuring an ?<sup>2</sup>-Arene Binding Mode and a Remarkable New Tetrameric Silver(I) Halide Form

Abstract

© 2015 American Chemical Society. A novel dinuclear ruthenium(II) complex containing two ortho-xylylene-linked bis(NHC) ligands (NHC = N-heterocyclic carbene) has been synthesized via transmetalation from a silver-NHC complex. Each ruthenium atom in the dinuclear complex is chelated through the two carbene carbon atoms and, unusually, an ?<sup>2</sup>-bound xylylene ring, two separate bis(NHC) units being linked by a Ru(µ-Cl)<inf>3</inf>Ru core. The same bis(NHC) ligand has yielded a neutral tetranuclear 4:2 AgBr:bis(NHC) complex, where ligand steric constraints seemingly inhibit formation of structures derivative of the more familiar "cubane" or "step" forms, resulting in an interesting new structural type. (Chemical Equation Presented).