Chrality Probing of Chlorotetrabutyratodiruthenium (II,III) Complexes with vic-amino Alcohols by Circular Dichroism Spectroscopy

The circular dichroism (CD) spectra of a variety of vic-amino alcohols in the presence of chlorotetrabutyratodiruthenium(II,III) as an auxiliary chromophore were measured in acetonitrile and chloroform. The method was tested in several model compounds containing acyclic and cyclic amino alcohols, and among them biologically important adrenergic drugs and amino sugars. The study demonstrated that the sign of the Cotton effects obtained is determined by the preferred helicity of the O-C-C-N unit in the chiral complex formed in situ. On this basis, a rule was formulated that correlates a positive (negative) sign of the O-C-C-N torsional angle with a positive (negative) Cotton effect arising around 350 nm and/or with negative (positive) signs of CD spectra bands occurring around 300 and 400 nm.