Synthesis, crystal structure and thermal properties of di-μ-iodido-bis­[bis­(2-chloro­pyrazine-κN)copper(I)]

Reaction of copper(I) iodide in pure 2-chloro­pyrazine leads to the formation of a few crystals of the title compound, [Cu(2)I(2)(C(4)H(3)ClN(2))(4)] or (CuI)(2)(2-chloro­pyrazine)(4), which was characterized by single-crystal X-ray diffraction. In its crystal structure, the Cu(I) cations are each tetra­hedrally coordinated by two iodide anions and two 2-chloro­pyrazine ligands and are linked into binuclear complexes consisting of (CuI)(2) rings located on centers of inversion. PXRD investigations of a few crystals obtained from the suspension indicate that the title compound is contaminated with a small amount of the 2-chloro­pyrazine-deficient compound CuI(2-chloro­pyrazine) already reported in the literature. PXRD investigations prove that the title compound immediately decomposes at room temperature into CuI(2-chloro­pyrazine) and this might be the reason why no pure samples can be obtained. TDA–TG–MS investigations shows two mass losses, the first of which corresponds to the formation of CuI(2-chloro­pyrazine), whereas in the second mass loss CuI is formed.