Intramolecular Hydroalkylation as a Route to Strained Dicationic Bis(arene) [3]Ruthenocyclophanes

Base-promoted intramolecular hydroalkylation of the carbon−carbon triple bond in the ruthenium bis(arene) complexes [( p -cymene)Ru( η 6 -C 6 H 5 C⋮CR)][OTf] 2 ( 1, R = Et; 2, R = Ph; OTf = O 3 SCF 3 ) generates the strained [3]ruthenocyclophane complexes 3 and 4, in which a propenyl (−CH 2 CR CH−) group bridges the two arene ligands. The presence of the propenyl bridge results in a bent-metallocene structure for the [3]ruthenocyclophane cation in 4, with an angle of 11.8° between the arene ligands.