In this study, we focus on the substituent effect of the diketone ligands on the structural variation of £]- diketonato metal complexes containing N,N-dimethyl formamide (DMF). Three £]-diketones (hfac, bztf, bzbz) were used, and six-, five-, four- coordinated complexes were found accordingly. It is surprising to find that all six metal-oxygen bonds in the M(hfac)2(DMF)2 complexes are of equal length, seemly in violation of Jahn-Teller theorem. Possible reasons for this observation were discussed in this thesis.