Novel Reactions of Cyclooctatetraene (COT)-Coordinated Diiron Cationic Bridging Carbyne Complexes with Nucleophiles

Abstract

The COT-coordinated diiron cationic bridging carbyne complexes [Fe2(μ-CAr)(CO)4(η8-C8H8)][BF4] (1, Ar = C6H5; 2, Ar = p-CH3C6H4; 3, Ar = p-CF3C6H4) were prepared by the reactions of the diiron bridging alkoxycarbene complexes [Fe2{μ-C(OC2H5)Ar}(CO)4(η8-C8H8)] with HBF4·Et2O at low temperature. Cationic 3 reacts with NaSR (R = C2H5, p-CH3C6H4) in THF at low temperature to afford diiron bridging sulfonylcarbene complexes [Fe2{μ-C(SO2R)C6H4CF3-p}(CO)4(η8-C8H8)] (7, R = C2H5; 8, R = p-CH3C6H4), while the reactions of 1−3 with NaBH4 under similar conditions gave diiron bridging arylcarbene complexes [Fe2{μ-C(H)Ar}(CO)4(η8-C8H8)] (9, Ar = C6H5; 10, Ar = p-CH3C6H4; 11, Ar = p-CF3C6H4). Complexes 1−3 can also react with anionic carbonylmetal compounds Na[M(CO)5(CN)] (4, M = Cr; 5, M = Mo; 6, M = W) to produce diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [Fe2{μ-C(Ar)NCM(CO)5}(CO)4(η8-C8H8)] (12, Ar = C6H5, M = Cr; 13, Ar = p-CH3C6H4, M = Cr; 14, Ar = p-CF3C6H4, M = Cr; 15, Ar = C6H5, M = Mo; 16, Ar = p-CH3C6H4, M = Mo; 17, Ar = p-CF3C6H4, M = Mo; 18, Ar = C6H5, M = W; 19, Ar = p-CH3C6H4, M = W; 20, Ar = p-CF3C6H4, M = W). Unexpectedly, aniline and 2-naphthylamine react with cationic 1 and 3 to give novel COT-coordinated iron carbene complexes [Fe2{C(Ar)NHAr‘}(μ-CO)(CO)3(η8-C8H8)] (21, Ar = C6H5, Ar‘ = C6H5; 22, Ar = p-CF3C6H4, Ar‘ = C6H5; 23, Ar = p-CF3C6H4, Ar‘ = 2-naphthyl). In solution, products 21−23 were transformed into chelated iron carbene complexes [Fe2{C(Ar)NAr‘}(CO)4(η2:η3:η2-C8H9)] (24, Ar = C6H5, Ar‘ = C6H5; 25, Ar = p-CF3C6H4, Ar‘ = C6H5; 26, Ar = p-CF3C6H4, Ar‘ = 2-naphthyl) in high yields. The structures of complexes 7, 8, 11, 14, 15, 20, 22, and 24 have been established by X-ray diffraction studies.