New coordination compounds of copper(II) and cobalt(II) with 5-amino-2-chloro-3-methylpyridine (L1) and 3-amino-2-chloro-5-methylpyridine (L2) of the following composition: (HL1)2[CuCl4] (1), (HL1)2[CoCl4]·HCl·H2O (2), (HL2)2[CuCl4]·H2O (3), (HL2)2[CuCl4]·2H2O (4) and (HL2)2[CoCl4] (5), have been synthesized. In an acetone environment, L1 may undergo a Schiff condensation reaction and the product of its complexation [CuL1*Cl3] (6) was also obtained. The compounds have been investigated by single-crystal X-ray diffraction, simultaneous TG–DSC analysis, IR and diffuse reflectance spectroscopy, and temperature-dependent magnetic susceptibility measurements. Exchange interactions between the unpaired electrons of the metal ions have a different character depending on the composition of the complexes. For the Cu(II) compounds: 1, 2D-ferromagnetic layer, J = 13.53(15) K; 3, strong-rung ladder, Jrung = −7.26(1) K, Jrail = −1.87(2) K; 4, uniform chain, J = −4.1(1) K. The magnetic properties of the Co(II) compounds are dominated by single-ion anisotropy with D = −22(1) K (2) and −8.7(2) K (5). The copper(II) complexes show thermochromic behavior.