Syntheses and characterization of novel tri- and hexa-nuclear zinc complexes with biomimetic chelate ligands

Abstract

Reaction of Zn(ClO₄)₂·6H₂O with pentadentate 1,3-bis(salicylidenamino)propan-2-ol (H₂hsalpn) and the tridentate 4-methyl-2,6-bis(morpholinomethyl)phenol (Hbmmp) yielded the trinuclear zinc complex [Zn₃(O₂CPh)₂(hsalpn)₂]·2MeOH 1 and the hexanuclear zinc compound [Zn₆(OH)₆(bmmp)₃][ClO₄]₃2. The complexes were characterized by single-crystal X-ray diffraction analyses. Both structures were solved using direct methods and refined on F by full-matrix least squares. Complex 1 consists of one central zinc ion which is octahedrally co-ordinated and two terminal metals surrounded by five donor atoms in the form of a square pyramid. The left and right wing zinc ions are connected to the central metal atom via two phenolate oxygens of the dinucleating ligand and the oxygens of the benzoate ion. The six equivalent tetrahedrally co-ordinated zinc ions in 2 are arranged in form of a regular trigonal prism. Three dinuclear subunits are connected to each other by hydroxide groups. Both compounds display a new type of structure for homotri- and homohexanuclear zinc complexes.