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

Abstract

A template 2:2:4 condensation of 2,6-diformyl-4-methyl-phenol, triethylenetetramine and zinc acetate gave rise to the crystallisation of [{Zn 4(H 4L 1)(OAc) 4}{Zn(OAc) 3(H 2O)}(OAc)] · 7H 2O ( 1 · 7H 2O), being H 6L 1 a macrocyclic diphenolate Schiff base ligand. Changing some operation conditions, other template reactions yielded dinuclear complexes of the type Zn 2(L n )(OAc) · xH 2O, where H 3L n ( 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 Bu t , respectively) and triethylenetetramine. After recrystallisation, these two latter complexes could be X-ray characterised as Zn 2(L 2)(OAc) · 1.25H 2O · 0.5MeCN ( 2 · 1.25H 2O · 0.5MeCN), and Zn 2(L 3)(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 Zn 2(L 4)(OAc)(HOAc) · 2H 2O ( 4 · 2H 2O), where H 3L 4 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.