C-C and C-H bond activation of dialkylmethylenecyclopropane promoted by rhodium and iridium complexes.: Preparation and structures of M(η1:η2-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 degreesC to form the 3-butenyl complexes of these metals, M{eta(1):eta(2)-CH2C(CH2CH2Ph)(2)CH=CH2}(CO)(PPh3)(2) (1, M = Rh; 2, M = Ir). Heating 1 at 55 degreesC liberates 1,1-bis(2-phenylethyl)-1,3-butadiene, while the thermal reaction of 2 at 110 degreesC 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 degreesC and with IrH(CO)(PPh3)(3) at 115 degreesC afford the alkenyl complexes trans-Rh{(Z)-CH=CHC(CH2CH2Ph)(2)CH3}-(CO)(PPh3)(2) (3) and trans-Ir{(E)-CH=CHC(CH2CH2Ph)(2)CH3}(CO)(PPh3)(2) (4), respectively. The reaction mechanisms are discussed on the basis of the results of the reactions under different conditions. HCequivalent toCC(CH2CH2Ph)(2)CH3 reacts with MH(CO)(PPh3)(3) (M = Rh, Ir) to afford the alkynyl complexes trans-M{Cequivalent toCC(CH2CH2Ph)(2)CH3}(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 H-2.