One-pot synthetic approach to isolate a single isomer of bis(diethylenetriamine)cobalt(III) cation in bulk using benzoates and the isomeric effects of the cation on ion association with anions

Herein, we report the syntheses and characterization of three complexes of composition mer -[Co(dien) 2 ]Cl( p -BBz) 2 ·H 2 O ( 1 ), s - fac -[Co(dien) 2 ]( o , p -DNBz) 3 ·H 2 O ( 2 ) and mer -[Co(dien) 2 ]Cl( p -MBz) 2 ·4H 2 O ( 3 ) in the continuation of our earlier work, where benzoate (Bz), p -chlorobenzoate (CBz), p -nitrobenzoate (NBz) and p -aminobenzoate (ABz) were used.

The isomeric identification of complex cation was initially made on the basis of spectroscopic characterization (UV–visible, IR and NMR). The binding properties of [Co(dien) 2 ] 3+ with benzoates ( p -BBz, o , p -DNBz, p -MBz, Bz, CBz, NBz or ABz) have been studied using standard UV–visible spectroscopic titrations in aqueous medium and comparison indicate ion association constants of s - fac > mer . The single-crystal X-ray diffraction structure analysis of 3 reveals the presence of discrete ions ([Co(dien) 2 ] 3+ , chloride, p -MBz) along with four lattice water molecules.