Synthesis and characterisation of [Ru6C(CO)14] cluster complexes of some [2.2]- and [2.2.2]-cyclophane ligands

Abstract

Some [Ru₆C(CO)₁₄] cluster complexes bearing the [2.2]ortho-, anti-[2.2]meta- and [2.2.2]para-cyclophane ligands have been prepared, isolated and characterised. The molecular structure of two new compounds [Ru₆C(CO)₁₄(meta-C₁₆H₁₆)] 2 and [Ru₆C(CO)₁₄(para-C₂₄H₂₄)] 4 have been established by X-ray diffraction studies which show that the cyclophane ligands are bound in an apical η⁶ mode in both cases. This is at variance with the face-capping µ₃-η²∶η²∶η² mode observed in the previously reported structure of [Ru₆C(CO)₁₄(para-C₁₆H₁₆)] 1. Spectroscopic evidence obtained for [Ru₆C(CO)₁₄(ortho-C₁₆H₁₆)] 3 suggests that the cyclophane ligand is bound in an apical η⁶ mode too. The synthesis of 1 via the redox coupling of [Ru₅C(CO)₁₄]^2– with [Ru(η⁶-C₁₆H₁₆)(NCMe)₃]²⁺ is presented as an alternative to the thermolysis of [Ru₃(CO)₁₂] with [2.2]paracyclophane in heptane.