ISOLATION AND CRYSTAL-STRUCTURE OF A DIMERIC OXOMOLYBDENUM(V) COMPLEX CONTAINING 2 ETHOXY BRIDGES AND ONE ETHANOL BRIDGE

Reaction of MoCl5 with EtOH in CHCl3 has given the complex (Cl2OMo(mu-OEt)2(mu-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, P2(1)2(1)2(1), a = 8.186(2), b = 8.319(2), c = 24.114(4) angstrom, 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, P2(1)/c, a = 8.449(1), b = 22.127(2), c = 19.526(2) angstrom, beta = 96.06(1)-degrees, 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, H-1 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 angstrom).