Only one fac isomer was synthesized in the [Co(pema) (amp) Cl]2+ system (pema= yV-pyridin-2-ylmethyl-ethane-1,2-diamine, amp = 2- aminomethylpyridine). This isomer was assigned by using 2D NMR technique and single crystal X-ray diffraction analysis. The results show that C-H…π interaction exists in the title isomer. A computational result of RHF/LANL2DZ optimized structure and total energy shows that the isomers with C H…π structure have lower total energy, and that stability and isomeric preference of isomer are related to the C H…π interaction in the isomer.

Key words: COBALT COMPLEX, ISOMER, PYRIDINE P, NMR, XRD, ETHANEDIAMINE P, STABILITY