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)₅M=C(OEt)(C≡CPh) (M = Cr, W)

Abstract

From the room temperature reaction of the transition metal alkynyl Fischer carbene complexes (CO)₅M=C(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-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{μ-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'{μ-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{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 spectroscopies. Crystallographic analysis of the compound Fe₂(CO)₆{μ-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.