Influence of some reaction conditions on the obtaining of tetra- and dinuclear zinc complexes of some Schiff bases derived from 2,6-diformyl-4-alkyl-phenols

A template 2:2:4 condensation of 2,6-diformyl-4-methyl-phenol, triethylenetetramine and zinc acetate gave rise to the crystallisation of [{Zn4(H4L1)(OAc)4}{Zn(OAc)3(H2O)}(OAc)] · 7H2O (1 · 7H2O), being H6L1 a macrocyclic diphenolate Schiff base ligand. Changing some operation conditions, other template reactions yielded dinuclear complexes of the type Zn2(Ln)(OAc) · xH2O, where H3Ln (n = 2, 3) are podant triphenolate Schiff base ligands derived from a 3:1 condensation of the corresponding 2,6-diformyl-4-alkyl-phenol (alkyl = Me or But, respectively) and triethylenetetramine. After recrystallisation, these two latter complexes could be X-ray characterised as Zn2(L2)(OAc) · 1.25H2O · 0.5MeCN (2 · 1.25H2O · 0.5MeCN), and Zn2(L3)(OAc) (3). Furthermore, after addition of a 3:1 molar ratio of 2-amino-4-methyl-phenol to 3, this underwent imidazolidine hydrolysis and a double imine condensation, yielding Zn2(L4)(OAc)(HOAc) · 2H2O (4 · 2H2O), where H3L4 is an acyclic pentadentate Schiff base derived from the 1:2 condensation of 2,6-diformyl-4-tert-butyl-phenol and 2-amino-4-methyl-phenol.

Graphical abstractThe influence of the reaction conditions employed in the obtaining of di- and tetranuclear complexes derived from condensation of 2,6-diformyl-4-alkyl-phenol, triethylenetetramine, and zinc acetate have been studied.Figure optionsDownload full-size imageDownload as PowerPoint slide