Zinc and cadmium complexes with versatile hexadentate Schiff base ligands. The supramolecular self-assembly of a 3-D cage-like complex

摘要

Mono- and poly-nuclear neutral complexes have been obtained by electrochemical reaction of zinc or cadmium anodes with potentially hexadentate ligands H_4L~n (n = 1-3). The ligands were prepared by 2:1 condensation of 3-hydroxysalicylaldehyde and 1, 2-diaminopropane, 1, 3-diaminopropane or 1, 4-diaminobutane, respectively. They can act either as N_2O_2 dianionic in mononuclear complexes or as N_2O_4 tetraanionic in polynuclear complexes, where metal ions are held together by #mu#-phenoxo bridges. X-Ray diffraction study of self-assembled [Zn_8(L~3)_4(H_2O)_3]·H_2O·1/4MeCN shows a 3-D cage-like crystal structure, where the ligand units display O_2 + N_2O_2 + O_2 polynucleating behaviours.