Di-μ-methanolato-bis[(η4-tetrafluorobenzobarrelene)rhodium(I)]

The versatile synthetic precursor methanolate-bridged title rhodium complex, [Rh2(CH3O)2(C12H6F4)2] or [Rh(mu-OCH3)(tfbb)]2 [tfbb = tetrafluorobenzobarrelene or 3,4,5,6-tetrafluorotricyclo[6.2.2.02,7]dodeca-2(7),3,5,9,11-pentaene], has been structurally characterized. The asymmetric unit contains half a molecule that can be expanded via a twofold axis. The title compound has been shown to be a dinuclear rhodium complex where each metal centre is coordinated by two O atoms from two bridging methanolate groups and by the olefinic bonds of a tfbb ligand. Comparison of the bite angles of tfbb, norbornadiene (nbd) and cyclooctadiene (cod) olefins in their ?4-coordination to rhodium reveals similarities between the tfbb and nbd ligands, which are much more rigid than cod. The short distance found between the distorted square-planar metal centres [2.8351 (4) angstrom] has been related to the syn conformation of the folded core `RhORhO' ring.