Circular dichroism spectra of 2-substituted propionatopentaaminocobalt(II) complexes

Abstract

The preparations of a series of optically active complexes with the general formula Co(NH₃)₅(OCOCH(X)CH₃)²⁺ are reported for X = NH₃⁺, OH, F, Cl, Br, C₂H₅, and C₆H₅. The circular dichroism spectra of the complexes have been measured in aqueous solution, in the presence of salts of polarizable anions, and in KBr disks. The spectra have been analysed in terms of three Cotton effects under the ¹A_1g → ¹T_1g cubic absorption band and found to be consistent with a +, -, - sign pattern for the L- isomer, corresponding to the two components of the ¹A_1g → ¹E_g (D_4h) and to the ¹A_1g → A_2g (D_4h) transition, respectively.