Ultrahigh chiral anisotropy factors in quasi-one-dimensional platinum compounds

Optically active, quasi-one-dimensional Pt-based compounds of the Magnus’ green salt type [Pt(NH2R)4][PtCl4] where R denotes (S)-3,7-dimethyloctyl or (R)-2-ethylhexyl were synthesized. The optically active side groups in the corresponding complexes were found to induce circular dichroism (CD) in the dz 2–pz transition between platinum atoms of adjacent coordination units. Interestingly, a bisignate Cotton effect was observed, indicative of a helical structure of [Pt(NH2R)4][PtCl4]. The absolute values of the chiral anisotropy factors were of the order of 0.1, which is among the highest values reported for metal complexes.