Chemical modification of the metal-carbene appendage in new, trimetallic adducts of Fe<SUB>2</SUB>(CO)<SUB>6</SUB>( &#956;-EE') (E = S, Se and E' = Se, Te) and alkynyl fischer carbene complexes (CO)<SUB>5</SUB>M=C(OEt)(C&#8801;CPh) (M = Cr, W)

From the room temperature reaction of the transition metal alkynyl Fischer carbene complexes (CO)5M=C(OEt)(C&#8801;CPh) (M = Cr, W) with the homochalcogenide compounds Fe2(CO)6(&#956;-E2) (E = S, Se, Te), the following new trimetallic adducts were obtained: [(CO)6Fe2E2{&#956;-PhC=CC(OEt)}M(CO)5] (1-5; 1, 30%, E = S, M = Cr; 2, 85%, E = Se, M = Cr; 3, 85%, E = Se, M = W; 4, 28%, E = Te, M = Cr; 5, 25%, E = Te, M = W). Alkoxy groups are readily replaced by amino groups in adducts 2, 3, and 5 at room temperature as syn- and anti-isomers, [(CO)6Fe2E2{&#956;-PhC=CCN(H)R}M(CO)5] (syn-8a-f and anti-8a-f; where R = CH3, CH2Ph, CH2CH=CH2), in 70-90% yield. When a methanolic solution of [(CO)6Fe2EE'{&#956;-PhC=CC(OEt)}M(CO)5] (E - E'; E = S, Se; E' = Se, Te; M = Cr, W) was stirred at room temperature for 1-2 days, the ester and ortho ester derivatives (CO)6Fe2{&#956;-EC(Ph)=C(CO)(OR)E'} (12-15) and (CO)6Fe2{&#956;-EC(Ph)=CC(OR)(OMe)2E'} (16-19) (R = CH3, C2H5) were formed. All compounds were characterized by IR and 1H, 13C, 77Se, and 125Te NMR spectroscopies. Crystallographic analysis of the compound Fe2(CO)6{&#956;-SC(Ph)=CC(OCH3)2(OC2H5)Te} (17) established its structure as a Fe2STe tetrahedral butterfly core containing the ortho ester unit, C(Ph)=C-C(OCH3)2(OC2H5)} as a bridge between the two wing-tip chalcogens