Four new metal-organic complexes of the formula [CrLCl2] (1), [CuLCl2] (2), [MnLCl2H2O] (3), and [NiL(OH)(2)2NO(3)] (4) [L=N-(1-Pyrazin-2-yl-ethylidene)-ethane-1,2-diamine, L-2=N,N-Bis-(1-pyrazin-2-yl-ethylidene)-ethane-1,2-diamine] have been synthesized and characterized by infrared method, elemental analysis, X-ray powder diffraction analysis, and single-crystal X-ray diffraction techniques. Their heat stability was tested by thermo gravimetric analyzer. X-ray structure analysis reveals that complexes 1-4 are all 0 D structure. The L ligand have many types of coordination modes that make these complexes as having different configuration - stackings and/or hydrogen bonding interactions, which seem to be effective in stabilizing these crystal structures.