Preparation of optically active 1,3-diphenyl-1,3-propanediamine (dppn) and the circular dichroism of trans-[CoCl2(S,S-dppn)2]+ and [Co(S,S-dppn)3]3+.

1,3-Diphenyl-1,3-propanediamine (dppn) was prepared from 1,3-diphenyl-2-propen-1-one. The meso and racemic isomers were isolated. The racemate was resolved into enantiomers with (+)D-di-O-benzoyltartrate. The absolute configuration of the free diamine was determined by comparing the circular dichroism (CD) spectrum of trans-[CoCl2(S,S- or R,R-dppn)2]+ with that of trans-[CoCl2(R,R-2,4-pentanediamine)2]+. The absolute configurations of Δ- and Λ-[Co(S,S-dppn)3]3+ were also assigned on the basis of the CD spectra.