Unusual reactions of cationic bridging carbyne complexes of dimethylsilane-bridged bis(eta(5)-cyclopentadienyl)diiron tricarbonyl with nucleophiles. A route to iron-sulfur cluster bridging carbene complexes

The reactions of diiron cationic carbyne complexes [Fe-2(mu -CO)(mu -CAr)(C O)(2){(eta (5)-C5H4)(2)Si(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 temper ature afford diiron bridging mercaptocarbene complexes [Fe-2(mu -CO){mu -C( SR)Ar}(CO)(2){eta (5)-C5H4)(2)Si(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 [(mu -SLi)(mu -SC6H5)Fe-2(CO)(6)] to give the novel iron-sulfur cluster bridging carbene complex [Fe-2(mu -CO)(mu -CC 6H4CF3-p)(CO)(2){(eta (5)-C5H4)(2)Si(CH3)(2)}(mu -S)(mu -SC6H5)Fe-2(CO)(6)] (18). Analogous iron-sulfur cluster bridging carbene complexes [Fe-2(mu -C O)(mu -CAr)(CO)(2)(eta (5)-C5H5)(2)-(mu -S)(mu -SC6H5)Fe-2(CO)(6)] (19, Ar = C6H5; 20, Ar = p-CH3C6H4) can also be obtained by the reactions of diiron cationic carbyne complexes [Fe-2(mu -CO)(mu -CAr)(CO)(2)(eta (5)-C5H5)(2)] BBr4 (7, Ar = C6H5; 8, Ar = p-CH3C6H4) with [(mu -SLi)(mu -SC6H5)Fe-2(CO)(6 )]. The structures of complexes 9, 13, 16, and 18 have been established by X-ray crystallography.