Thermolysis of Fe-3(CO)(9)(mu(3)-Se)(mu(3)-E) (E = S, Te) with Cp2Mo2(CO)(6) and formation of new mixed-chalcogenide, mixed Fe-Mo carbonyl clusters. Crystal structures of Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(2)(mu(4)-Te), Cp2Mo2Fe2(CO)(7)(mu(3)-Se)(mu(3)-Te) and Cp2Mo2Fe2(CO)(6)(mu(3)-S)(mu(3)-Se)(mu(4)-Se)

The thermolytic reaction of Fe-3(CO)(9)(mu(3)-Se)(mu(3)-Te) with Cp2Mo2(CO)(6) in benzene yielded the new mixed-metal, mixed trichalcogenide clusters Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(mu(3)-Te)(mu(4)-Te) (2a), Cp2Mo2Fe2(CO)(6)(mu(3)-Te)(2)(mu(4)-Se) (2b) and Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(2)(mu(4)-Te) (3a), Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(mu(3)-Te)(mu(4)-Se) (3b) as well as the dichalcogenide cluster Cp2Mo2Fe2(CO)(7)(mu(3)-Se)(mu(3)-Te) (8). Similarly, the thermolysis of Fe-3(CO)(9)(mu(3)-S)(mu(3)-Se) with Cp2Mo2(CO)(6) in benzene afforded the new mixed-metal, mixed trichalcogenide clusters Cp2Mo2Fe2(CO)(6)(mu(3)-S)(2)(mu(4)-Se) (10), Cp2Mo2Fe2(CO)(6)(mu(3)-S)(mu(3)-Se)(mu(4)-Se) (11) and the dichalcogenide cluster Cp2Mo2Fe2(CO)(7)(mu(3)-S)(mu(3)-Se) (13). In the case of 10 and 11, formation of isomers containing the sulphido in the mu(4)-site was not observed. Compounds 2a and 2b could also be obtained when Cp2Mo2Fe2(CO)(6)(mu(3)-Te)(2) was refluxed with selenium powder in benzene. Similarly, refluxing of benzene solutions containing selenium powder and Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(mu(3)-Te) formed 3a and 3b, and sulphur powder with Cp2Mo2Fe2(CO)(6)(mu(3)-S)(mu(3)-Se) or Cp2Mo2Fe2(CO)(6)(mu(3)-Se)(2) yielded the compounds 10 and 11 respectively. The new clusters have been characterised by IR and by H-1, C-13, Se-77 and Te-125 NMR spectroscopy. Clusters 3a, 8 and 11 have also been structurally characterised by single-crystal X-ray diffraction methods. (C) 1997 Elsevier Science S.A.