Synthesis, X-ray and NMR characterisation of cobalt(III) coordination compounds with 2-guanidinobenzimidazole

The synthesis and characterisation of cobalt(III) coordination compounds with 2-guanidinobenzimidazole (2gb), namely [Co(2gb)3]Cl2(NO3)·H2O, [Co(2gb)3]Cl(NO3)2·H2O, [Co(2gb)3]Cl3·3H2O and [Co(2gb)3](Cl3CCOO)3·H2O, are presented. The compounds with the 2-guanidinobenzimidazole ligand were synthesised from [Co(NH3)4CO3]NO3 or Na3[Co(CO3)3]·3H2O or from cobalt(II) chloride. 1H, 13C and 2D NMR spectra together with the X-ray diffraction data for the distorted octahedral [Co(2gb)3]3+ cation showed that only the mer isomer was formed.