General synthesis of 'salicylaldehyde half-unit complexes': structural determination and use as synthon for the synthesis of dimetallic or trimetallic complexes and of 'self-assembling ligand complexes'

Template synthesis of the ligand resulting from the monocondensation of 1,2-diaminoethane with salicylaldehyde was realized successfully in the presence of copper(II) ions and nitrogen bases (imidazole, pyridine). This 'half-unit' ligand, named 4-(2-hydroxyphenyl)-3-aza-3 buten-1-amino or N-(2-aminoethyl)salicylaldimine, is abbreviated as SEH or SE in its deprotonated form. This reaction can be extended to other diamines. The complex [SECuImH]ClO4 crystallizes in the monoclinic space group P2(1)/c (no. 14) with 4 formula weights in the cell having dimensions a = 9.020(1), b = 21.293(2), c = 8.384(1) Angstrom and beta = 107.64(1)degrees. It presents several synthetic applications. Particular attention was paid to the dinuclear imidazole-bridged complexes, with imidazole bridges being free or included in a tetradentate Schiff base, via study of their magnetic properties. Some examples of self-assembling complexes are also given, along with [(SECu)(3)OH](ClO4)(2) . H2O for which magnetic results confirm the trinuclear structure. (C) 1998 Elsevier Science S.A. All rights reserved.