C−C and C−H Bond Activation of Dialkylmethylenecyclopropane Promoted by Rhodium and Iridium Complexes. Preparation and Structures of M(η<sup>1</sup>:η<sup>2</sup>-CH<sub>2</sub>CR<sub>2</sub>CHCH<sub>2</sub>)(CO)(PPh<sub>3</sub>)<sub>2</sub> and <i>trans</i>-M(CHCHCMeR<sub>2</sub>)(CO)(PPh<sub>3</sub>)<sub>2</sub> (M = Rh, Ir, R = CH<sub>2</sub>CH<sub>2</sub>Ph)

2,2-Bis(2-phenylethyl)-1-methylenecyclopropane reacts with RhH(CO)(PPh<sub>3</sub>)<sub>3</sub> at room temperature and with IrH(CO)(PPh<sub>3</sub>)<sub>3</sub> at 70 °C to form the 3-butenyl complexes of these metals, M{<i>η</i><sup>1</sup>:<i>η</i><sup>2</sup>-CH<sub>2</sub>C(CH<sub>2</sub>CH<sub>2</sub>Ph)<sub>2</sub>CHCH<sub>2</sub>}(CO)(PPh<sub>3</sub>)<sub>2</sub> (<b>1</b>, M = Rh;<b> 2</b>, M = Ir). Heating <b>1</b> at 55 °C liberates 1,1-bis(2-phenylethyl)-1,3-butadiene, while the thermal reaction of <b>2</b> at 110 °C forms a mixture of 3-methyl-3-vinyl-1,5-diphenyl-1-pentene (48% NMR yield) and 3-methyl-3-vinyl-1,5-diphenylpentane (15% NMR yield). The reactions of excess amounts of 2,2-bis(2-phenylethyl)-1-methylenecyclopropane with RhH(CO)(PPh<sub>3</sub>)<sub>3</sub> at 55 °C and with IrH(CO)(PPh<sub>3</sub>)<sub>3</sub> at 115 °C afford the alkenyl complexes <i>trans</i>-Rh{(<i>Z</i>)-CHCHC(CH<sub>2</sub>CH<sub>2</sub>Ph)<sub>2</sub>CH<sub>3</sub>}(CO)(PPh<sub>3</sub>)<sub>2</sub> (<b>3</b>) and <i>trans</i>-Ir{(<i>E</i>)-CHCHC(CH<sub>2</sub>CH<sub>2</sub>Ph)<sub>2</sub>CH<sub>3</sub>}(CO)(PPh<sub>3</sub>)<sub>2</sub> (<b>4</b>), respectively. The reaction mechanisms are discussed on the basis of the results of the reactions under different conditions. HC⋮CC(CH<sub>2</sub>CH<sub>2</sub>Ph)<sub>2</sub>CH<sub>3</sub> reacts with MH(CO)(PPh<sub>3</sub>)<sub>3</sub> (M = Rh, Ir) to afford the alkynyl complexes <i>trans</i>-M{C⋮CC(CH<sub>2</sub>CH<sub>2</sub>Ph)<sub>2</sub>CH<sub>3</sub>}(CO)(PPh<sub>3</sub>)<sub>2</sub> (<b>5</b>, M = Rh;<b> 6</b>, M = Ir) via oxidative addition of the C(alkyne)−H bond to the metal center and subsequent elimination of H<sub>2</sub>.