Tetranuclear Zn(II) complexes with compartmental and dicyanamido ligands: synthesis, structure, and luminescent properties

Abstract

New tetranuclear compounds have been obtained by reacting binuclear complexes, [Zn2L n (μ-OH)(H2O)2](ClO4)2, with sodium dicyanamide (HL n are end-off bicompartmental ligands resulting from condensation between 2,6-diformyl-p-cresol with N,N-dimethyl-ethylenediamine or 2-aminomethyl-pyridine). The complexes, [{L1(μ-OH)Zn2}(μ 1,5-dca)2{Zn2(μ-OH)L1}](ClO4)2 (1) and [{Zn2L2(μ 3-OH)(dca)}2](ClO4)2 · 2H2O (2), have been characterized by single-crystal X-ray diffraction. The angular nature of the bridging dicyanamido induces the “M” shape of the tetranuclear cationic unit in 1. The tetranuclear cation, because of its particular shape, acts as a receptor toward one perchlorate ion, which is hydrogen bonded to the hydroxo groups. This tetranuclear unit in 2 has a defective heterocubane structure. The luminescence properties of the new tetranuclear complexes have been investigated.