Iodide-bridged dinuclear copper(I) complex with cyanopyrazine and its conversion into bis(tetrazolato)copper(II) complex via [3 + 2] cycloaddition: synthesis, structure and self-assembly

A copper(I) complex [Cu(L1)2I]2 (1) [L1 = 2-cyanopyrazine] has been prepared by the reduction of copper(II) with iodide in the presence of L1. This complex is made to undergo [2 + 3] cycloaddition with sodium azide to prepare a copper(II) complex, [Cu(L2)2(H2O)2]·H2O (2) [HL2 = 5-pyrazinyltetrazole]. Both the complexes have been characterized by elemental and spectral analysis and single-crystal X-ray diffraction studies. Copper(I) centre has tetrahedral geometry in complex 1, whereas copper(II) centre assumes octahedral geometry in complex 2. Supramolecular interactions in both complexes were also explored.