Synthesis of η-arene rhenium compounds using rhenium atoms. Crystal structures of [Re2(η-C6H6)(η-C6H8)2(µ-H)2] and [Re(η-C6H6)(η-C6H8)H]

Abstract

The new compounds [Re₂(η-C₆H₆)(η-C₆H₈)₂(µ-H)₂], [Re(η-C₆H₆)(η-C₆H₈)H], [Re(η-C₆H₆)(η⁵-C₇H₇)], [Re(η-C₆H₆)(η⁵-C₇H₉)], and [Re(η⁵-C₉H₇)(η⁶-C₉H₈)] are described, including the determination of the crystal structures of the first two compounds. The new compounds have been made by co-condensation of rhenium atoms with benzene–cyclohexene, benzene–cyclohexa-1,3-diene (or cyclohexene), benzene–cycloheptatriene, benzene–cycloheptatriene, and pure indene, respectively. Co-condensation of rhenium atoms with benzene–cyclopentadiene yields a mixture of [Re(η-C₆H₆)(η-C₅H₅)] and [Re(η-C₅H₅)₂H]. Characterisation of the η-cycloheptatriene and η-indene derivatives required two-dimensional (¹H–¹H) COSY and (¹³C–¹H) correlation n.m.r. spectroscopy. Co-condensation of rhenium atoms with cyclohexane–trimethylphosphine gives [Re(η-C₆H₆)(PMe₃)₂H] where the η-benzene ligand derives from the cyclohexane.