C−C and C−H Bond Activation of Dialkylmethylenecyclopropane Promoted by Rhodium and Iridium Complexes. Preparation and Structures of M(η ¹ :η ² -CH ₂ CR ₂ CHCH ₂ )(CO)(PPh ₃ ) ₂ and trans -M(CHCHCMeR ₂ )(CO)(PPh ₃ ) ₂ (M = Rh, Ir, R = CH ₂ CH ₂ Ph)

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