Three coordination polymers, [ML 2 (H 2 O) 2 ] (M = Co (1), Ni (2), Mn (3)), were prepared from metal acetates (M(CH 3 COO) 2 ·4H 2 O) and 3−pyridinepropionic acid (HL = (3-py)-CH 2 CH 2 COOH) by solvent-layer methods. By contrast, a discrete molecular compound, trans-[Pd(HL) 2 Cl 2 ] (4), was synthesized by replacing benzonitrile (PhCN) ligands in trans-[Pd(PhCN) 2 Cl 2 ] with HL under microwave-heating conditions. Compounds 1-3 have a 2D framework, and compound 4 contains a square-planar Pd metal.