Synthesis and crystal structure of an encapsulated fragment of MoO2 in the unique Mo8 oxo-cluster compound [Mo8O8Cl6(µ3-O)4(OH)2(µ-OH)4(µ-OEt)4(HOEt)4] and its relevance to the sol–gel synthesis of molybdenum oxides

Reaction of the dimeric oxomolybdenum(V) complex [Cl2OMo(µ-OEt)2(µ-HOEt)MoOCl2]1 with SbF3 in toluene followed by overlaying with light petroleum followed an unexpected course to give crystals of the complex [Mo8O8Cl6(µ3-O)4(OH)2(µ-OH)4(µ-OEt)4(HOEt)4]2 in low yield. The crystal structure of 2[triclinic, space group P, a= 10.803(5), b= 11.159(6), c= 11.659(6)A, α= 69.66(3), β= 64.06(3), γ= 66.258(24)°, Z= 1, R= 0.058, wR2= 0.143] has been determined and reveals a new structural type for an M8 cluster which is closely related to the distorted rutile structure adopted by MoO2. Incorporating two Mo4 layers connected with each other by a layer of four bridging oxygen atoms in a centrosymmetric arrangement, it serves as a model for intermediates in the sol–gel synthesis of molybdenum oxides.

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