Chemical Modification of the Metal−Carbene Appendage in New, Trimetallic Adducts of Fe2(CO)6(μ-EE‘) (E = S, Se and E‘ = Se, Te) and Alkynyl Fischer Carbene Complexes (CO)5MC(OEt)(C⋮CPh) (M = Cr, W)

From the room temperature reaction of the transition metal alkynyl Fischer carbene complexes (CO)5MC(OEt)(C⋮CPh) (M = Cr, W) with the homochalcogenide compounds Fe2(CO)6(μ-E2) (E = S, Se, Te), the following new trimetallic adducts were obtained:  [(CO)6Fe2E2{μ-PhCCC(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{μ-PhCCCN(H)R}M(CO)5] (syn-8a−f and anti-8a−f; where R = CH3, CH2Ph, CH2CHCH2), in 70−90% yield. When a methanolic solution of [(CO)6Fe2EE‘{μ-PhCCC(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{μ-EC(Ph)C(CO)(OR)E‘} (12−15) and (CO)6Fe2{μ-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 spectroscopi...