Tetraruthenium cluster isomers containing both C6H8 and [2.2]paracyclophane ligands: a new face-bridging co-ordination mode for a C6 aromatic ring
Abstract
The reaction of [Ru3(CO)9(µ3-η2 : η2 : η2-C16H16)]1 with 2.2 molar equivalents of Me3NO in dichloromethane containing cyclohexa-1,3-diene afforded the new tetrahedral complex [Ru4(CO)9(η4-C6H8)(µ3-C16H16)]2 in modest yield. The thermolysis of [Ru4(CO)12(µ4-C6H8)]3 in octane containing an excess of [2,2]paracyclophane (C16H16) and Me3NO afforded the two new butterfly isomers [Ru4(CO)9(µ4-C6H8)(η6-C16H16)]4 and [Ru4(CO)9(µ4-C6H8)(µ3-η2 : η2 : η2-C16H16)]5. Heating compound 4 results in its irreversible conversion to 5. Compounds 2 and 4 have been characterised in the solid state by single-crystal X-ray diffraction and in 2 the [2,2]paracyclophane ring bonds to the cluster via an unusual µ3-η1 : η2 : η2 bonding mode unseen before for an arene ring.