A Stable Trinuclear Zinc Cluster Assembled from a Thiazolylazo Dye and Zinc Acetate: Preparation, Structural Characterization and Spectroscopic Studies

Abstract

AbstractA thiazolylazo dye, 5‐(diethylamino)‐2‐(2‐thiazolylazo)phenol (HL), containing potential tridentate binding sites was synthesized in high yield and well characterized. In solution, the reaction of zinc acetate and the deprotonated ligand, L–, results in the instantaneous formation of the supramolecular trinuclear species [Zn3L2(OAc)4] (1). UV/Vis and 1H NMR spectroscopic titration experiments in solution confirmed that the ligand and zinc salt interact spontaneously with each other and produce exclusively the polymetallic complex with the metal‐to‐ligand ratio of 3:2. The crystal structures of both the ligand and coordination complex are reported in this paper. The aromatic part of HL is planar and, significantly, the intermolecular C–H···π hydrogen bonds and thiazo ring‐S···π weak interactions observed here should be responsible for the orthorhombic space group P212121. The structure of 1 reveals a linear trinuclear zinc cluster. The two L– units are linked to three zinc atoms in an N2O tridentate mode, and the four acetate anions are chelated to three metal centers as bridges to result in two pentacoordinate and one hexacoordinate zinc centers. The resulting bridging Zn1–Zn2–Zn1A array is linear by symmetry, with a nonbonding Zn···Zn distance of 3.390 Å and a Zn1···Zn2···Zn1A angle of 180.0°. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)