[{µ-(Pyridazine-N1:N2)}Fe2(µ-CO)(CO)6]
(1) reacts with aryllithium reagents, ArLi (Ar = C6H5, m-CH3C6H4) followed by treatment with Me3SiCl to give the novel pyridazine-coordinated diiron bridging siloxycarbene complexes [(C4H4N2)Fe2{µ-C(OSiMe3)Ar}(CO)6]
(2, Ar = C6H5; 3, Ar =
m-CH3C6H4). Complex 2 reacts with HBF4·Et2O at low temperature to yield a cationic bridging carbyne complex [(C4H4N2)Fe2(µ-CC6H5)(CO)6]BF4
(4). Cationic 4 reacts with NaBH4 in THF at low temperature to afford the diiron bridging arylcarbene complex [(C4H4N2)Fe2{µ-C(H)C6H5}(CO)6]
(5). Unexpectedly, the reaction of 4 with NaSCH3 under similar conditions gave the bridging arylcarbene complex 5 and a carbonyl-coordinated diiron bridging carbene complex [Fe2{µ-C(SCH3)C6H5}(CO)7]
(6), while the reaction of NaSC6H4CH3-p with 4 affords the expected bridging arylthiocarbene complex [(C4H4N2)Fe2{µ-C(SC6H4CH3-p)C6H5}(CO)6]
(7), which can be converted into a novel diiron bridging carbyne complex with a thiolato-bridged ligand, [Fe2(µ-CC6H5)(µ-SC6H4CH3-p)(CO)6]
(8). Cationic 4 can also react with the carbonylmetal anionic compound Na2[Fe(CO)4] to yield complex 5, while the reactions of 4 with carbonylmetal anionic compounds Na[M(CO)5(CN)]
(M = Cr, Mo, W) produce the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [(C4H4N2)Fe2-{µ-C(C6H5)NCM(CO)5}(CO)6]
(9, M = Cr; 10, M = Mo; 11, M = W). The structures of complexes 2, 5, 6, 8, and 9 have been established by X-ray diffraction studies.