Bidentate complexes between [Mo-2(OAc)(4)] and 1,3-diols (1-16) show several CD bands in the 250 - 600 nm range. A previously published sector rule for the prediction of the sign of band II at ca. 400 nm for rigid cyclic 1,3-diols is extended to open-chain (7-12) as well as ''semi-rigid'' 1,3-glycols (1-6 and 14-16). Their absolute configuration can be correlated with the sign of this CD band. This in situ complexation needs minute amounts of substance and therefore is a very convenient tool for the determination of the absolute configuration of such class of compounds.