Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

Compound [Fe2(μ-CO)2(CO)2(η5-C9H7)2] (1) reacts with aryllithium reagents, ArLi (Ar = C6H5, p-CH3C6H4, p-CF3C6H4) followed by alkylation with Et3OBF4 to give the diindenyl-coordinated diiron bridging alkoxycarbene complexes [Fe2{μ-C(OC2H5)Ar}(μ-CO)(CO)2(η5-C9H7)2] (2, Ar = C6H5; 3, Ar = p-CH3C6H4, 4, Ar = p-CF3C6H4). Complex 4 reacts with HBF4 · Et2O at low temperature to yield cationic bridging carbyne complex [Fe2(μ-CC6H4CF3-p)(μ-CO)(CO)2(η5-C9H7)2]BF4 (5). Cationic 5 reacts with NaBH4 in THF at low temperature to afford diiron bridging arylcarbene complex [Fe2{μ-C(H)C6H4CF3-p}(μ-CO)(CO)2(η5-C9H7)2] (6). The reaction of 5 with NaSC6H4CH3-p under the similar conditions gave the bridging arylthiocarbene complex [Fe2{μ-C(C6H4CF3-p)SC6H4CH3-p}(μ-CO)(CO)2(η5-C9H7)2] (7). Complex 5 can also react with carbonylmetal anionic compounds Na[M(CO)5(CN)] (M = Cr, Mo, W) to produce the diiron bridging aryl(penta-carbonylcyanometal)carbene complexes [Fe2{μ-C(C6H4CF3-p)NCM(CO)5}(μ-CO)(CO)2(η5-C9H7)2] (8, M = Cr; 9, M = Mo; 10, M = W). The structures of complexes 4, 6, 7, and 10 have been established by X-ray diffraction studies.