Unusual Reactions of Cationic Bridging Carbyne Complexes of Dimethylsilane-Bridged Bis(η5-cyclopentadienyl)diiron Tricarbonyl with Nucleophiles. A Route to Iron−Sulfur Cluster Bridging Carbene Complexes

Abstract

The reactions of diiron cationic carbyne complexes [Fe2(μ-CO)(μ-CAr)(CO)2{(η5-C5H4)2Si(CH3)2}]BBr4 (4, Ar = C6H5; 5, Ar = p-CH3C6H4; 6, Ar = p-CF3C6H4) with NaSR (R = CH3, C6H5, p-CH3C6H4) in THF at low temperature afford diiron bridging mercaptocarbene complexes [Fe2(μ-CO){μ-C(SR)Ar}(CO)2{(η5-C5H4)2Si(CH3)2}] (9, Ar = C6H5, R = CH3; 10, Ar = C6H5, R = C6H5; 11, Ar = C6H5, R = p-CH3C6H4; 12, Ar = p-CH3C6H4, R = CH3; 13, Ar = p-CH3C6H4, R = C6H5;14, Ar = p-CH3C6H4, R = p-CH3C6H4; 15, Ar = p-CF3C6H4, R = CH3; 16, Ar= p-CF3C6H4, R = C6H5; 17, Ar = p-CF3C6H4, R = p-CH3C6H4). Compound 6 reacts with [(μ-SLi)(μ-SC6H5)Fe2(CO)6] to give the novel iron−sulfur cluster bridging carbene complex [Fe2(μ-CO)(μ-CC6H4CF3-p)(CO)2{(η5-C5H4)2Si(CH3)2}(μ-S)(μ-SC6H5)Fe2(CO)6] (18). Analogous iron−sulfur cluster bridging carbene complexes [Fe2(μ-CO)(μ-CAr)(CO)2(η5-C5H5)2(μ-S)(μ-SC6H5)Fe2(CO)6] (19, Ar = C6H5; 20, Ar = p-CH3C6H4) can also be obtained by the reactions of diiron cationic carbyne complexes [Fe2(μ-CO)(μ-CAr)(CO)2(η5-C5H5)2]BBr4 (7, Ar = C6H5; 8, Ar = p-CH3C6H4) with [(μ-SLi)(μ-SC6H5)Fe2(CO)6]. The structures of complexes 9, 13, 16, and 18 have been established by X-ray crystallography.