An unusual cyclopentaannulation reaction:: Thermolysis of an α,β-unsaturated Fischer carbene complex anchored on a Fe2(CO)6(μ-Se)2 core

An unusual annulation of-a Fischer carbene complex anchored on a Fe-2(CO)(6)(mu-Se)(2) core is examined. Thermolysis of Fe-2(CO)(6){mu-SeC(Ph)=C(Se)[(OEt)C=Cr(CO)(5)]} in THF yields an unusual annulated product, [Fe-2(CO)(6)Se-2{mu-(CO)(3)Cr(eta(5)-C5H(CH2Ph)(Ph)(OEt))}] (1), as characterized by IR and H-1, C-13, and Se-77 NMR spectroscopies, and its structure has been established by single-crystal X-ray diffraction.