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 Cp2Mo 2(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), Cp2Mo2F e2(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 tri chalcogenide clusters Cp2Mo2Fe2(CO)(6)(mu(3)-S)(2)(mu(4)-Se) (10), Cp2 Mo2Fe2(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 a nd 11, formation of isomers containing the sulphido in the mu(4)-site was not observed. Compounds 2a and 2b could also be obtained when Cp2M o2Fe2(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 sulphu r 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 clu sters 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 c haracterised by single-crystal X-ray diffraction methods. (C) 1997 Els evier Science S.A.