Two iron(III) spin crossover complexes [Fe(⁵Cl-L)(NCS)] (1) and [Fe(⁵Cl-L)(NCSe)] (2) were synthesized with the pentadentate Schiff base ligand ⁵Cl-L and thiocyanato and selenocyanato as coligands. ⁵Cl-L, as an asymmetric {N₃O₂} donor Schiff base, was synthesized by a condensation reaction of 5-chlorosalicyladehyde using the asymmetric N-(2-aminoethyl)-1,3-propanediamine. The complexes exhibited a spin crossover at 280 (1) and 293 K (2), respectively, and were subjected to electron spin resonance (ESR) and Mössbauer spectroscopy at 77, 295 and 325 K. Ab initio CASSCF calculations followed by the NEVPT2 method were applied for predicting the g-tensor components as well as Mössbauer parameters.