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 CHdCH 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{ 4), respectively. The reaction mechanisms are discussed on the basis of the results of the reactions under different conditions. HCtCC(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{CtCC(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 .
Phenyl-1-methylenecyclopropane and 2,2diphenyl-1-methylenecyclopropane react with MH(CO)-(PPh 3 ) 3 (M ) Rh, Ir) to produce 1,3-dienes or the intermediate Rh and Ir complexes having a 3-butenyl ligand, depending on the conditions. The structures and chemical properties of the obtained complexes suggest plausible pathways for the ring-opening isomerization of the methylenecyclopropanes to the corresponding dienes.
The reaction of (C 5 Me 5 ) 2 Sm(THF) 2 with 2 equiv of benzophenone imine (Ph 2 CdNH) in THF at room temperature gave the samarocene(III) amine/ketimido complex (C 5 Me 5 ) 2 Sm-(NdCPh 2 )(NH 2 CHPh 2 ) (1) in 58% isolated yield. The use of 1 equiv of Ph 2 CdNH also afforded 1 as the only isolable product, albeit in a lower yield (ca. 20%). Deuterium-labeling experiments suggest that 1 is formed via hydrogen abstraction by the in-situ-generated imine radical anion species, followed by acid-base reaction between the resulting amido species and another molecule of Ph 2 CdNH. The reactions of 2 equiv of Sm(OAr) 2 (THF) 3 (Ar ) C 6 H 2t Bu 2 -2,6-Me-4) with N-phenyl benzophenone imine (Ph 2 CdNPh) and N-phenyl fluorenone imine (C 12 H 8 CdNPh) yielded the Sm(III) η 2 -imine-dianion/aryloxide complexes Sm(η 2 -Ph 2 -CNPh)(OAr)(THF) 3 (3, 65%) and Sm(η 2 -C 12 H 8 CNPh)(OAr)(THF) 3 (4, 77%), respectively, together with the byproduct Sm(OAr) 3 . The reaction of 1 equiv of Sm(OAr) 2 (THF) 3 with Ph 2 CdNPh also gave the imine-dianion complex 3, whereas an imine radical anion species was not observed. Similarly, the reactions of 2 equiv of Sm{N(SiMe 3 ) 2 } 2 (THF) 2 with Ph 2 -CdNPh and C 12 H 8 CdNPh yielded the η 2 -imine-dianion/silylamido complexes Sm(η 2 -Ph 2 -CNPh){N(SiMe 3 ) 2 }(THF) 3 (5, 87%) and Sm(η 2 -C 12 H 8 CNPh){N(SiMe 3 ) 2 }(THF) 3 (6, 71%), respectively. Complexes 3-6 represent the first examples of structurally characterized trivalent lanthanide η 2 -imine complexes.
[IrH(CO)(PPh3)3] promotes ring opening of 2-phenyl-1-methylenecyclopropane at room temperature to produce the Ir complex with a chelating 2-phenyl-3-butenyl ligand, [Ir{η2-CH2CH(Ph)CH=CH2-κC1}(CO)(PPh3)2] (1). The reaction of excess 2-phenyl-1-methylenecyclopropane with [IrH(CO)(PPh3)3] at 50 °C yields [Ir{η2-(o-C6H4)CH(Me)CH=CH2-κC1}(CO)(PPh3)2] (2), accompanied by the formation of 1-phenyl-1,3-butadiene and 2-phenyl-1,3-butadiene. 2,2-Diphenyl-1-methylenecyclopropane reacts with [IrH(CO)(PPh3)3] to afford [Ir{η2-CH2CPh2CH=CH2-κC1}(CO)(PPh3)2] (3) at 50 °C and [Ir{η2-(o-C6H4)CMe(Ph)CH=CH2-κC1}(CO)(PPh3)2] (4) at 100 °C. Heating a solution of 3 at 100 °C also forms 4 quantitatively. X-ray crystallography of 3 reveals a penta-coordinated structure around the Ir center bonded to a chelating 2,2-diphenyl-3-butenyl ligand. The reactions of 2,2-diphenyl-1-methylenecyclopropane and of 2,2-di(4-fluorophenyl)-1-methylenecyclopropane with [RhH(CO)(PPh3)3] at room temperature yield [Rh{η2-CH2CAr2CH=CH2-κC1}(CO)(PPh3)2] (5a: Ar = Ph, 5b: Ar = C6H4-F-4). The reactions at 50 °C cause ring opening of the substrate and orthometalation of the phenyl group to afford [Rh{η2-(o-C6H4)CMe(Ph)CH=CH2-κC1}(CO)(PPh3)2] (6a) and [Rh{η2-(o-C6H3-F-4)CMe(C6H4-F-4)CH=CH2-κC1}(CO)(PPh3)2] (6b), respectively. Formation of 1,1-diaryl-1,3-butadiene is observed during the reaction. Heating a solution of 5a at 50 °C produces 1,1-diphenyl-1,3-butadiene and an allylrhodium complex, 8, rather than 6a, although the reaction of excess 2,2-diphenyl-1-methylenecyclopropane with 5a at 50 °C affords 6a in 60%. The mechanisms of the above reactions are discussed based on the products and reaction rates. Coordination of P(OMe)3 to the Rh center of 5a causes insertion of the CO ligand into the Rh–C bond to afford [Rh{η2-CO-CH2CPh2CH=CH2-κC1}(P(OMe)3)3] (7).
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