A series of 2,6-bis(imidate)pyridine ligated Co(II) and Ni(II) complexes with general formula of [2,6-(2,6-iPr2C6H3N=COR)2C5H3N]MX2 (R=Me, M=Co, X=Cl (1a); R=Me, M=Ni, X=Br (2a); R=Et, M=Co, X=Cl (1b); R=Et, M=Ni, X=Br (2b); R=iPr, M=Co, X=Cl (1c); R=iPr, M=Ni, X=Br (2c); R=CH2CF3, M=Co, X=Cl (1d); R=CH2CF3, M=Ni, X=Br (2d); R=Ph, M=Co, X=Cl (1e); R=Ph, M=Ni, X=Br (2e); R=CH2Ph, M=Co, X=Cl (1f); R=CH2Ph, M=Ni, X=Br (2f)) were synthesized. Determined by single crystal X-ray analysis, complexes 1e and 2c with NNN tridentate ligands adopted approximate distorted square pyramidal configurations whereas complex 1f with tridentate NNO ligand displayed a distorted square pyramidal configuration. Activated by methylaluminoxane (MAO), these complexes exhibited high cis-1,4 selectivity towards 1,3-butadiene polymerization. The structure of substituent and polymerization conditions significantly influenced the catalytic behaviors of the complexes. The addition of PPh3 to the Co(II)-based systems enhanced the catalytic activity and switched the selectivity from cis-1,4 to 1,2 manner.