Correlation between stereochemistry and sign of cotton effects for degenerate transitions in spectra of binuclear clusters of molybdenum(II)

A correlation between the stereochemistry and sign of the Cotton effect for π → δ* transition in the spectra of dimolybdenum tetracarboxylates and related compounds has been accomplished by constructing, within the framework of a one-electron model of optical activity, a 32-sector rule based on data from x-ray structure analysis and circular dichroism for dimolybdenum tetra-(R)-mandelate. It has been shown that a positive value of the pseudoscalar function xyz(x2−y2)(a2-z2) corresponds to a negative Cotton effect for the π → δ* transition in the case in which the dominant contribution to this effect comes from Rx components of the rotator strength of the transition.