Abstract: The equilibrium constants and coordination numbers for axial reaction of cobalt(Ⅱ)tetrakis(4-trimethylamino phenyl)-porphyrin iodide hydrate(abb. Co(Ⅱ)TMAPPI)withnitrogen containing organic bases were measured by spectral technique. The results showthat Co(Ⅱ)TMAPPI forms 1:2 adducts with imidazoline(Im)and benzimidazoline(PhIm),but 1:1 adducts with pyridine(Py)and n-propylaniline(P₁NH₂). The mechanism of the auxi-liary catalytic effect of nitrogen containing organic bases on the electrocatalytic reductionof CO₂ with Co(Ⅱ)TMAPPI was discussed.

Key words: cobalt tetrakis(trimethylamino phenyl)-porphyriniodide, organic base, coordination reaction