in case of organic ligand there r several techniques for purification,but in case of metal complex(Cr,Mn,Fe,Co) with schiff base , i have not seen any literature for the purification of them except recrystallization. give some suggestion
There are a lot of reasons why silica and alumina can damage a compound: they are not neutral, they contain 12-15% water, they have a huge specific area (typically 550 m2/g) which greatly enhances interactions between the compound and the stationary phase, they can sort of "chelate" metals... Furthermore, in your case, imines (Schiff bases) are usually not stable to chromatography.
Although your metal complexes will likely not be stable enough, you can give it a try on 2D TLC to check for decomposition. Maybe adding 2-5% TEA in the eluent can limit damaging your compounds. If oxygen is a problem, you can manage to remove it from the solvents and carry out your column chromatography under argon.