Isolation and crystal structure of a dimeric oxomolybdenum(V) complex containing two ethoxy bridges and one ethanol bridge

Abstract

Reaction of MoCl₅ with EtOH in CHCl₃ has given the complex [Cl₂OMo(µ-OEt)₂(µ-HOEt)MoOCl₂]1 in essentially quantitative yield. Slow removal of the volatile material from the reaction mixture gives orange crystals of an unsolvated orthorhombic phase [C₆H₁₆Cl₄Mo₂O₅, P2₁2₁2₁, a= 8.186(2), b= 8.319(2), c= 24.114(4)Å, Z= 4, R= 0.0809, R′= 0.0784], while recrystallisation from CH₂Cl₂ gives a monoclinic phase incorporating partially occupied disordered CH₂Cl₂ of crystallisation and containing two molecules of 1 in the asymmetric unit [C₁₂H₃₂Cl₈Mo₄O₁₀·0.45CH₂Cl₂, P2₁/c, a= 8.449(1), b= 22.127(2), c= 19.526(2)Å, β= 96.06(1)°, Z= 4, R= 0.0427, R′= 0.0452]. Compound 1 is of structural interest because it exhibits the unusual feature of two Mo^V centres bridged by three oxygen atoms, while at the same time furnishing the first example of a bridging ethanol molecule. Compound 1 has been further characterised by IR, ¹H NMR and chemical analyses, while magnetic susceptibility measurements showed it to be diamagnetic. This result is consistent with the crystal structures which imply the presence of a Mo–Mo single bond (length ca. 2.69 Å).