Chemical shifts for proton signals of an imidazole ring coordinated to Co(III) move downfield as the total complex charge increases. However, the C(2) - H chemical shift of the imidazole ring in cis-[Co(en)2(N-mIm) OPO3H]°, which has no charge compared to those of cis-[Co(en)2(N-mIm) OPO3H]+ and cis}-[Co(en)2(N-mIm) OPO3H2]2 + , moves downfield. These unexpected phenomena could be attributed to an intramolecular interaction between the phosphate anion group and C(2) - H of the imidazole ligand.

Chemical shifts for proton signals of an imidazole ring coordinated to Co(III) move downfield as the total complex charge increases. However, the C(2) - H chemical shift of the imidazole ring in cis-[Co(en)2(N-mIm) OPO3H]°, which has no charge compared to those of cis-[Co(en)2(N-mIm) OPO3H]+ and cis}-[Co(en)2(N-mIm) OPO3H2]2 + , moves downfield. These unexpected phenomena could be attributed to an intramolecular interaction between the phosphate anion group and C(2) - H of the imidazole ligand.