The configurations of the four geometric mer-isomers in a new [Co(3, 3-tri)(ibn)Cl]^2^+(3, 3-tri=N-(3-aminoethyl)-1, 3-propanediamine; ibn=1, 2-diamino-2-methylpropane) system were assigned by using 2D NMR techniques such as gCOSY and NOESY. Solvent used was Me~2So=d~6 with the central peak of the CD~3 septet as the reference (^1^3C, δ39.37; ^1H, δ2.49 relative to SiMe~4). Comparing to the eluates from the chromatographic column, cation exchange media used was Dowex 50 W×2 (H^+ form, 200～400 mesh; Biorad), the first band contains the m2, the second band contains the m4, the third band contains the m1, the fourth band contains the m3 and the last band contains the f3. An ab initio computational result (RHF/LANL2DZ level) suggests why the facial isomer has been isolated and the distribution of the four mer-isomers is not different from those of [Co(2, 2-tri)(diamine)Cl]^2^+.

Key words: COBALT COMPLEX, OXAZOLE P, AB INITIO CALCULATION, REGULARITIES OF DISTRIBUTION, ISOMER