Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and Thermal Studies

[Image: see text] Three, PO(4)(3–)/HPO(4)(2–) and AsO(4)(3–)-incorporated, new tetranuclear complexes of copper(II) and zinc(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H(3)cpdp (H(3)cpdp = N,N′-Bis[2-carboxybenzomethyl]-N,N′-Bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper(II) chloride in the presence of either NaOH/Na(2)HPO(4)·2H(2)O or KOH/Na(2)HAsO(4)·7H(2)O lead to the isolation of the tetranuclear complexes Na(3)[Cu(4)(cpdp)(2)(μ(4)-PO(4))](OH)(2)·14H(2)O (1) and K(2)[Cu(4)(cpdp)(2)(μ(4)-AsO(4))](OH)·16(2)/(3)H(2)O (2), respectively. Similarly, the reaction of H(3)cpdp with zinc(II) chloride in the presence of NaOH/Na(2)HPO(4)·2H(2)O yields a tetranuclear complex, Na(H(3)O)(2)[Zn(4)(cpdp)(2)(μ(4)-HPO(4))]Cl(3)·12(1)/(2)H(2)O (3). All complexes are characterized by single-crystal X-ray diffraction and other analytical techniques, such as Fourier transform infrared and UV−vis spectroscopy, thermogravimetric and electrochemical studies. The solid-state molecular framework of each complex contains two monocationic [M(2)(cpdp)](+) (M = Cu, Zn) units, which are exclusively coordinated to either phosphate/hydrogen phosphate or arsenate groups in a unique mode. All three complexes exhibit a μ(4):η(1):η(1):η(1):η(1) bridging mode of the PO(4)(3–)/HPO(4)(2–)/AsO(4)(3–) groups, with each bridging among four metal ions. The thermal properties of all three complexes have been investigated by thermogravimetric analysis. Low-temperature magnetic studies of complexes 1 and 2 disclose moderate antiferromagnetic interactions mediated among the copper centers through alkoxide and phosphate/arsenate bridges. Electrochemical studies of complexes 1 and 2 in dimethylformamide using cyclic voltammetry reveal the presence of a fairly assessable one-electron metal-based irreversible reduction and one quasireversible oxidation couple.