Regioselective addition of mixed-chalcogenide iron carbonyl clusters Fe-2(CO)(6)(mu-EE') (E not equal E', E, E'=S, Se, Te) to a carbon-carbon triple bond activated by a metal carbene fragment. Structural characterization of new trimetallic adducts Fe-2(CO)(6){mu-SC(Ph)=C(Te)[(OEt)C=Cr(CO)(5)]}, Fe-2(CO)(6-) {mu-SC(Ph)=C(Se)[(OEt)C=W(CO)(5)]}, and Fe-2(CO)(6){mu-SeC(Ph)=C(Te)[(OEt)C=W(CO)(5)]}

Abstract

From the room-temperature reaction of the transition-metal alkynyl Fischer carbene complexes (CO)(5)M=C(OEt)(C=CPh) (M = Cr, W) with the mixed-chalcogenide compounds Fe-2(CO)(6)(mu-EE') (E not equal E', E, E' = S, Se, Te), the following new trimetallic adducts were obtained: Fe-2(CO)(6){mu-EC(Ph)=C(E')[(OEt)C=M(CO)(5)]} 1-6 (1, 85%, E = S, E' = Se, M = Cr; 2, 82%, E = S, E' = Se, M = W; 3, 84%, E = S, E' = Te, M = Cr; 4, 80%, E = S, E' = Te, M = W; 5, 83%, E = Se, E' = Te, M = Cr; 6, 81%, E = Se, E' = Te, M = W). In addition, trace amounts of the corresponding alkenyl Fischer carbene complexes (CO)(5)M=C(OEt){(CH=C(OMe)Ph} 7-8 (7, M = Cr; 8, M = W) were also formed in each case. Compounds 1-6 were characterized by IR and H-1, C-13, Se-77, and Te-125 NMR spectroscopy. Crystallographic analyses of the compounds 2, 3, and 6 were carried out. The structures of 2, 3, and 6 can be described as Fe2EE' (E, E' = S, Se, Te) tetrahedral butterfly cores containing the alkynyl Fischer carbene as a bridge between the two wingtip chalcogens with three terminally bonded carbonyl groups on each Fe atom.