Single and multiple insertion of arylallene into the Rh-H bond to give (π-allyl)rhodium complexes

The reaction of RhH(PPh3)(4) at room temperature with excess phenylallene, (4-methylphenyl)allene, (4-methoxyphenyl)allene, (4-tert-butylphenyl)allene, (4-chlorophenyl)allene, and (4-fluorophenyl)allene results in the insertion of four arylallene molecules into the Rh-H bond to afford Rh{eta(3)-CH2C[CH(Ar)] C(=CHAr)CH2C(=CHAr)CH2CH2CH=CHAr)} (PPh3)(2) (1, Ar = C6H5; 2, Ar = C6H4Me-p; 3, Ar = C6H4OMe-p; 4, Ar = C6H4-t-Bu-p; 4, Ar = C6H4Cl-p; 6, Ar = C6H4F-p), respectively. NMR (H-1, C-13, and P-31) spectroscopy was used to characterize the (pi-allyl)rhodium(I) complexes. Reaction of (4-methoxyphenyl)allene with RhD(PPh3-d(15))(4) gives 3-d(31), Rh{eta(3)-CH2C[CH(Ar)]C(=CHAr)CH2C(=CHAr)CH2CH2CD=CHAr)}(PPh3-d(15))(2) (Ar = C6H4OMe-p) whose vinylene hydrogen is deuterated selectively. Complexes 1 and 3 do not react further with arylallene at room temperature. Reaction of arylallenes with an equimolar amount of RhH(CO)(PPh3)3 leads to the insertion of a molecule into the Rh-H bond to give the (pi-allyl)rhodium complexes Rh(eta(3)-CH2CHCHC6H4X-p)(CO)(PPh3)(2) (9, X = Me; 10, X = OMe; 11, X = F; 12, X = Cl), while excess phenylallene reacts with the hydridorhodium complex to give a mixture of 1, Rh(eta(3)-CH2CHCHPh)(CO)(PPh3)(2), and unreacted RhR(CO)(PPh3)(3). A crystallographic study of 9 and H-1 NMR data for the complexes indicate that the aryl substituent has a syn orientation. The pi-allyl complexes react with monosubstituted acetylenes to give trans-Rh(C=CZ)(CO)(PPh3)(2) (13, Z = Ph; 14, Z = C6H4Me-p; 15, Z = SiMe3) accompanied by the generation of 1-arylpropene.