Isolation and characterization of [Fe2(CO)6Se2{μ-(CO)3Cr(η5-C5(H)(CH2Ph)(Ph)(OEt)}], [(CO)6Fe2{μ-EC(Ph)=C(E′)C(H)(OEt)}]2 and [(CO)6Fe2{μ-SC(H)(Ph)C(Te)=C(H)(OEt)}] from the thermolysis of Fischer carbene adducts [(CO)6Fe2EE′{μ-C(Ph)=C-C(OEt)=Cr(CO)5}] (E, E′ = Se and E = S, E′ = Te)

Thermolysis of the trimetallic adducts [(CO)(6)Fe2EE'{mu-C(Ph)=C-C(OEt)=Cr(CO)(5)}] 1a,b (1a: E = E' = Se; 1b: E = S, E' = Te) in refluxing THF yield the following complexes: [Fe-2(CO)(6)EE' {mu-(CO)(3)Cr(eta(5)-C-5(H)(CH2Ph)(Ph)(OEt)}], (2: E = E' = Se); [(CO)(6)Fe-2{mu-EC(Ph)=C(E')C(H)(OEt)}](2), (3a: E = E' = Se; 3b: E = S, E' = Te) and [(CO)(6)Fe-2{mu-EC(H)(Ph)C(E')=C(H)(OEt)}], (4: E = S, E' = Te), where the product formation depends on the nature of chalcogen atoms present in the trimetallic adducts 1a and 1b. All products have been characterized by IR and H-1-,C-13-, Se-77- and Te-125-NMR spectroscopy and structural types were unequivocally established by X-ray crystallographic analysis of compounds 3a and 4. (C) 1998 Elsevier Science S.A. All rights reserved.