Olefin-aminocarbyne coupling in diiron complexes: Synthesis of new bridging aminoallylidene complexes |
| |
| Authors: | Luigi Busetto |
| |
| Institution: | Dipartimento di Chimica Fisica e Inorganica, Università di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy |
| |
| Abstract: | The bridging aminocarbyne complexes Fe2{μ-CN(Me)(R)}(μ-CO)(CO)2(Cp)2]SO3CF3] (R = Me, 1a; Xyl, 1b; 4-C6H4OMe, 1c; Xyl = 2,6-Me2C6 H3) react with acrylonitrile or methyl acrylate, in the presence of Me3NO and NaH, to give the corresponding μ-allylidene complexes Fe2{μ-η1:η3- Cα(N(Me)(R))Cβ(H)Cγ(H)(R′)}(μ-CO)(CO)(Cp)2] (R = Me, R′ = CN, 3a; R = Xyl, R′ = CN, 3b; R = 4-C6H4OMe, R′ = CN, 3c; R = Me, R′ = CO2Me, 3d; R = 4-C6H4OMe, R′ = CO2Me, 3e). Likewise, 1a reacts with styrene or diethyl maleate, under the same reaction conditions, affording the complexes Fe2{μ-η1:η3-Cα(NMe2)Cβ(R′)Cγ(H)(R″)}(μ-CO)(CO)(Cp)2] (R′ = H, R″ = C6H5, 3f; R′ = R″ = CO2Et, 3g). The corresponding reactions of Ru2{μ-CN(Me)(CH2Ph)}(μ-CO)(CO)2(Cp)2]SO3CF3] (1d) with acrylonitrile or methyl acrylate afford the complexes Ru2{μ-η1:η3-Cα(N(Me)(CH2Ph))Cβ(H)Cγ(H)(R′)}(μ-CO)(CO)(Cp)2] (R′ = CN, 3h; CO2Me, 3i), respectively.The coupling reaction of olefin with the carbyne carbon is regio- and stereospecific, leading to the formation of only one isomer. C-C bond formation occurs selectively between the less substituted alkene carbon and the aminocarbyne, and the Cβ-H, Cγ-H hydrogen atoms are mutually trans.The reactions with acrylonitrile, leading to 3a-c and 3h involve, as intermediate species, the nitrile complexes M2{μ-CN(Me)(R)}(μ-CO)(CO)(NC-CH CH2)(Cp)2]SO3CF3] (M = Fe, R = Me, 4a; M = Fe, R = Xyl, 4b; M = Fe, R = 4-C6H4OMe, 4c; M = Ru, R = CH2C6H5, 4d).Compounds 3a, 3d and 3f undergo methylation (by CH3SO3CF3) and protonation (by HSO3CF3) at the nitrogen atom, leading to the formation of the cationic complexes Fe2{μ-η1:η3-Cα(N(Me)3)Cβ(H)Cγ(H)(R)}(μ-CO)(CO)(Cp)2]SO3CF3] (R = CN, 5a; R = CO2Me, 5b; R = C6H5, 5c) and Fe2{μ-η1:η3-Cα(N(H)(Me)2)Cβ(H)Cγ(H)(R)}(μ-CO)(CO)(Cp)2]SO3CF3] (R = CN, 6a; R = CO2Me, 6b; R = C6H5, 6c), respectively.Complex 3a, adds the fragment Fe(CO)2(THF)(Cp)]+, through the nitrile functionality of the bridging ligand, leading to the formation of the complex Fe2{μ-η1:η3-Cα(NMe2)Cβ(H)Cγ(H)(CNFe(CO)2Cp)}(μ-CO)(CO)(Cp)2]SO3CF3] (9).In an analogous reaction, 3a and Fe2{μ-CN(Me)(R)}(μ-CO)(CO)2(Cp)2]SO3CF3], in the presence of Me3NO, are assembled to give the tetrameric species Fe2{μ-η1:η3-Cα(NMe2)Cβ(H)Cγ(H)(CNFe2{μ- CN(Me)(R)}(μ-CO)(CO)(Cp)2])}(μ-CO)(CO)(Cp)2]SO3CF3] (R = Me, 10a; R = Xyl, 10b; R = 4-C6H4OMe, 10c).The molecular structures of 3a and 3b have been determined by X-ray diffraction studies. |
| |
| Keywords: | Aminocarbyne Dinuclear complexes Allylidene Coupling reactions C-C bond formation |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
