Influence of the synthetic conditions on a formation of 1-D, 2-D and 3-D copper–chloride coordination polymers

Abstract

By means of electrochemical alternating current synthesis starting from a methanol solution of CuCl₂·2H₂O and dabco (dabco = 1,4-diazabicyclo[2.2.2]octane) titrated with HCl, a salt of (H₂dabco)Cu₂Cl₄ composition (I) was obtained. It consists of infinite chains composed from vertex-sharing Cu₂Cl₂ rhombs and diprotonated (H₂dabco)²⁺ cations. The use of ethanol as a solvent and a higher CuCl₂·2H₂O : dabco ratio lead to the formation of the (H₂dabco)Cu₃Cl₅ (II) salt. Its inorganic part consists of infinite corrugated ribbons in which each half-loop is closed by an additional chloride bridge. The decrease of the CuCl₂·2H₂O : dabco ratio leads to the appearance of the compound (H₂dabco)₅Cu₁₂Cl₂₂·H₂O (III), which contains unique anionic 2-D (Cu^I₁₂Cl₂₂)¹⁰⁻ networks. Syntheses carried out in aprotic solvents led to the formation of known (H₂dabco)CuCl₃ salt. Recrystallization of the compound III from dymethyl sulfoxide (DMSO) unexpectedly led to the appearance of two copper(I) chloride complexes with in situ formed dymethylsulfide (DMS): the already known CuCl·DMS and observed for the first time (CuCl)₇(DMS)₃ (IV). The latter contains two types of infinite copper–chloride columns, consisting of cubane-like Cu₄Cl₄ and prismane-like Cu₆Cl₆ clusters. μ-Sulfur (DMS) bridges connect the above columns to form a 3-D network. Crystallisation from the initial CuCl₂·2H₂O – dabco – HCl mixture yielded deep-red crystals of the unknown (H₂dabco)Cu₂^IICl₆ salt (V) among other products. Its structure consists of infinite cupro(II)-chloride chains and discrete (H₂dabco)²⁺ cations.