The Syntheses, structures and properties of the complexes of 2-oxo- propionic acid (4-pyridinecarbonyl)-hydrazone with alkaline earth metals are reported in this paper. The crystal structures of Mg and Ba complex were determined by x-ray single crystal diffraction analysis, the results show that two complexes are monoclinic of space group P2~1/c; the cell parameters are as follows: MgL.4H~2O, a=1.053, b=1.1308, c=1.1948nm, β =103.24ⅲ, Z=4, Vc=1.3859nm^3, Dc=1.45g/cm^3, R=0.00379. Ba(HL)~2.9h~2O, a=1.4082, b=0.7263, c=2.7798nm, β=93.14ⅲ, Z=4, Vc=2.8389nm^3, Dc=1.67g/cm^3, R=0.0404. Besides, typical IR bands of the bonding in various forms and thermal stability are discussed in comparison with each other.

Key words: METHYLACETIC ACID P, CARBONYL COMPOUNDS, PYRIDINE P, HYDRAZONE P, CRYSTAL STRUCTURE, THERMAL STABILITY, CALCIUM COMPLEX, MAGNESIUM COMPLEX, STRONTIUM COMPLEX, BARIUM COMPLEX