CYCLOHEXENYL [2.2]PARACYCLOPHANE COMPLEXES OF RUTHENIUM(II) - HIGHLY FLUXIONAL AGOSTICS FROM THE SEQUENTIAL REDUCTION OF ARENES

Reduction of the (arene)(paracyclophane)ruthenium(II) complex [Ru(eta6-C6Me6)(eta6-C16H16)][BF4]2 (1b) with Na[BH4] gives in contrast to the analogous Red-Al reduction a mixture of ruthenium(0) diene products, chiefly the 1,3-diene complex [Ru(eta4-1,3-C6Me6H2) (eta6-C16H16)](2c). Complex 2c reacts with aqueous H[BF4] to generate the agostic species [Ru(eta3-C6Me6H3)(eta6-C16H16)][BF4](3). The complex is highly fluxional with the single endo agostic hydrogen atom exchanging rapidly between the two terminal olefinic carbon atoms of the cyclohexadiene unit. The formulation of the complex has been confirmed by the preparation of the di-deutero analogue.