The compound (dienH3)2(pydc)3, 1; dien: diethyltriamine, pydcH2: pyridine-2,6-dicarboxylic acid, as a proton transfer ligand was applied to synthesize (dienH3)2[Ce(pydc)3]316.75H2O, 2. The compounds were examined by elemental analysis, IR, UV and NMR spectroscopy. In addition, the compound 2 was studied by TG analysis, single crystal X-ray diffractometry and computational calculations. Geometry optimizations were carried out using B3PW91 hybrid density functional and quasirelativistic effective core potentials (ECP46MWB) to represent the atomic core of cerium and 6–311G(d, p) basis set that used to describe the electrons of oxygen, nitrogen, carbon and hydrogen atoms. Also, natural bond orbital (NBO) analysis at the B3 PW91/A level gives the natural electron population and the natural charge for each atom. Cerium atom in 2 is nine-coordinated with three (pydc)2- groups giving an anionic complex which is balanced by (dienH3)3? in the crystal structure. Several intermolecular interactions including O–HO and N–HO hydrogen bonds, face-to-face and edge-to-face stackings are responsible to stabilize the extended structure
