C−C and C−H Bond Activation of Dialkylmethylenecyclopropane Promoted by Rhodium and Iridium Complexes. Preparation and Structures of M(η12-CH2CR2CHCH2)(CO)(PPh3)2 and trans-M(CHCHCMeR2)(CO)(PPh3)2 (M = Rh, Ir, R = CH2CH2Ph)

2,2-Bis(2-phenylethyl)-1-methylenecyclopropane reacts with RhH(CO)(PPh3)3 at room temperature and with IrH(CO)(PPh3)3 at 70 °C to form the 3-butenyl complexes of these metals, M{η1:η2-CH2C(CH2CH2Ph)2CHCH2}(CO)(PPh3)2 (1, M = Rh; 2, M = Ir). Heating 1 at 55 °C liberates 1,1-bis(2-phenylethyl)-1,3-butadiene, while the thermal reaction of 2 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)(PPh3)3 at 55 °C and with IrH(CO)(PPh3)3 at 115 °C afford the alkenyl complexes trans-Rh{(Z)-CHCHC(CH2CH2Ph)2CH3}(CO)(PPh3)2 (3) and trans-Ir{(E)-CHCHC(CH2CH2Ph)2CH3}(CO)(PPh3)2 (4), respectively. The reaction mechanisms are discussed on the basis of the results of the reactions under different conditions. HC⋮CC(CH2CH2Ph)2CH3 reacts with MH(CO)(PPh3)3 (M = Rh, Ir) to afford the alkynyl complexes trans-M{C⋮CC(CH2CH2Ph)2CH3}(CO)(PPh3)2 (5, M = Rh; 6, M = Ir) via oxidative addition of the C(alkyne)−H bond to the metal center and subsequent elimination of H2.