Polystyrene‐immobilised imidazole ligands; synthesis and complex formation with transition metal salts

Abstract

AbstractThe modification of polystyrenes (1 – 8% cross‐linked) by imidazole ligands, via chloromethylation, is described. The resulting resins, having 10–40% of the phenyl groups substituted by a CH2(N)‐imidazolyl group, have been treated with first‐row transition metal salts under varying conditions. Upon reaction of the modified polymer with the transition metal salts in CHCl3, a shrinking of the polymer is observed which is explained by additional cross‐linking by the metal ions. The final products have the general formula Mt(PS‐Iz)m (NnBuIz)nX2, in which PS‐Iz stands for a polystyrene‐bound imidazole ligand, NnBuIz for N‐butylimidazole (a ligand used to solubilize the metal salts in CHCl3) and X for the anion (perchlorate, nitrate, tetrafluoroborate, chloride, bromide). Metal ions used are Co(II), Ni(II), Cu(II), and Zn(II); values of 2–6 have been found for m in most cases. The value of n usually is very small (0,2–1,0) in most cases. Spectroscopically the polymeric coordination compounds behave like the corresponding monomeric coordination compounds, Mt(N‐benzylimidazole)mX2, indicating that the imidazole ligands in the polymer are quite flexible in their coordination behaviour, except in case of very low degrees of substitution or high degrees of cross‐linking.