The post-synthetic reaction between p-anisaldehyde and the spin-crossover compd. [Fe(NH2-trz)3](NO3)2 (NH2-trz = 4-amino-1,2,4-triazole) was explored, obtaining different degrees of transformation from 23% to full conversion by varying the reaction time. The post-synthetic SCO complexes obtained were studied by magnetometry, powder x-ray diffraction (PXRD), elemental anal., solid state NMR and IR and compared with the corresponding compds. obtained by direct synthetic routes, revealing new spin crossover properties.