Olefin-aminocarbyne coupling in diiron complexes: Synthesis of new bridging aminoallylidene complexes

摘要

The bridging aminocarbyne complexes [Fe-2{mu-CO(Me)(R)} (mu-CO)(CO)(2)(CP)(2)][SO3CF3] (R =Me, 1a; Xyl, 1b; 4-C6H4OMe, 1e; Xyl = 2,6-Me2C6 H-3) react with acrylonitrile or methyl acrylate, in the presence of Me3NO and NaH, to give the corresponding P-allylidene complexes [Fe-2(mu-eta(1):eta(3) - C-alpha(N(Me)(R))C-alpha(H)C-gamma(H)(R')}(mu-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, la reacts with styrene or diethyl maleate, under the same reaction conditions, affording the complexes [Fe-2{mu-eta(1):eta(3)-C-alpha(NMe2)C-beta(R')C-gamma(H)(R '')}(mu-CO)(CO)(CP)(2)] (R'=H, R ''=C6H5,3f, R'=R ''=CO2Et, 3g). The corresponding reactions of [Ru-2{mu-CN(Me)(CH2Ph)}(mu-CO)(CO)(2)(CP)(2)][SO3CF3] (1d) with acrylonitrile or methyl acrylate afford the complexes [Ru-2{mu-eta(1):eta C-3(alpha)(NMe2)(CH2Ph)}C-beta(H)C-gamma(H)(R')}(mu-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 C-beta-H, C-gamma-H hydrogen atoms are mutually trans. The reactions with acrylonitrile, leading to 3a-c and 3h involve, as intermediate species, the nitrile complexes [M-2{mu-CN(Me)(R)} (mu-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 [Fe-2{ mu-eta(1):eta(3)-C-alpha(N(Me)(3) C-beta(H)C-gamma(H)(R)}(mu-CO)(CO)(Cp)(2) [SO3CF3] (R = CN, 5a; R = CO2Me, 5b; R = C6H5, 5c) and [Fe-2{ mu-eta(1):eta(3)-C-alpha(N(H)(Me)(2) C-beta(H)C-gamma(H)(R)}(mu-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. [Fe-2{ mu-eta(1):eta(3)-C-alpha(NMe)(2) C-beta(H)C-gamma(H)(R)}(mu-CO)(CO)(Cp)(2) [SO3CF3] (9). In an analogous reaction, 3a and [Fe-2{mu-CN(Me)(R)}(mu-CO)(CO)(Cp)(2) [SO3CF3] in the presence of Me3NO, are assembled to give tile tetrameric species [Fe-2{ mu-eta(1):eta(3)-C-alpha(N(Me)(2) C-beta(H)C-gamma(H)(CN[Fe-2{mu-CN(Me)(R)}(mu-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. (c) 2007 Elsevier BN. All rights reserved.