Unusual Reactions of Cationic Bridging Carbyne Complexes of Bis(η5-cyclopentadienyl)diiron Tricarbonyl with Carbonylmetal Anions. A Route to Diiron Bridging Carbyne Complexes

Abstract

The reactions of cationic carbyne complexes of diiron, [Fe2(μ-CO)(μ-CPh)(CO)2(η5-C5H5)2]BBr4 (1), with the anionic carbonylmetal compounds Na[M(CO)5CN] (3, M = Cr; 4, M = Mo; 5, M = W) in THF at low temperature afford the novel bridging carbyne complexes [Fe2(μ-CO)(μ-CPh)(CO)2(η5-C5H5)2NCM(CO)5] (6, M = Cr; 7, M = Mo; 8, M = W). In contrast to the reaction of 1, the cationic carbyne complex [Fe2(μ-CO)(μ-CC6H4Me-p)(CO)2(η5-C5H5)2]BBr4 (2) reacts with carbonylmetal anions 3−5 under the same conditions to produce the novel bridging p-tolyl(pentacarbonylcyanotungsten)carbene complexes [Fe2(μ-CO){μ-C(C6H4Me-p)(CO)2(η5-C5H5)2NCM(CO)5}] (9, M = Cr; 10, M = Mo; 11, M = W). However, the analogous reaction of Na[Fe(CO)4CN] with 1 yields the diiron bridging phenylcarbene complex [Fe2(μ-CO){μ-C(H)Ph}(CO)2(η5-C5H5)2] (12). The structures of 7, 8, and 11 have been established by X-ray crystallography.