Thermolysis of Fe₃(CO)₉(μ₃-Se)(μ₃-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(μ₃-Se)₂(μ₄-Te), Cp₂Mo₂Fe₂(CO)₇(μ₃-Se)(μ₃-Te) and Cp₂Mo₂Fe₂(CO)₆(μ₃-S)(μ₃-Se)(μ₄-Se)

Abstract

The thermolytic reaction of Fe₃(CO)₉(μ₃-Se)(μ₃-Te) with Cp₂Mo₂(CO)₆ in benzene yielded the new mixed-metal, mixed trichalcogenide clusters Cp₂Mo₂Fe₂(CO)₆(μ₃-Se)(μ₃-Te)(μ₄-Te) (2a), Cp₂Mo₂Fe₂(CO)₆(μ₃-Te)₂(μ₄-Se) (2b) and Cp₂Mo₂Fe₂(CO)₆(μ₃-Se)₂(μ₄-Te) (3a), Cp₂Mo₂Fe₂(CO)₆(μ₃-Se)(μ₃-Te)(μ₄-Se) (3b) as well as the dichalcogenide cluster Cp₂Mo₂Fe₂(CO)₇(μ₃-Se)(μ₃-Te) (8). Similarly, the thermolysis of Fe₃(CO)₉(μ₃-S)(μ₃-Se) with Cp₂Mo₂(CO)₆ in benzene afforded the new mixed-metal, mixed trichalcogenide clusters Cp₂Mo₂Fe₂(CO)₆(μ₃-S)₂(μ₄-Se) (10), Cp₂Mo₂Fe₂(CO)₆(μ₃-S)(μ₃-Se)(μ₄-Se) (11) and the dichalcogenide cluster Cp₂Mo₂Fe₂(CO)₇(μ₃-S)(μ₃-Se) (13). In the case of 10 and 11, formation of isomers containing the sulphido in the μ₄-site was not observed. Compounds 2a and 2b could also be obtained when Cp₂Mo₂Fe₂(CO)₆(μ₃-Te)₂ was refluxed with selenium powder in benzene. Similarly, refluxing of benzene solutions containing selenium powder and Cp₂Mo₂Fe₂(CO)₆(μ₃-Se)(μ₃-Te) formed 3a and 3b, and sulphur powder with Cp₂Mo₂Fe₂(CO)₆(μ₃-S)(μ₃-Se) or Cp₂Mo₂Fe₂(CO)₆(μ₃-Se)₂ yielded the compounds 10 and 11 respectively. The new clusters have been characterised by IR and by ¹H, ¹³C, ⁷⁷Se and ¹²⁵Te NMR spectroscopy. Clusters 3a, 8 and 11 have also been structurally characterised by single-crystal X-ray diffraction methods.