Copper‐Azide‐Thioarylazoimidazoles – Structure, Spectra, Redox Properties, Magnetism and Theoretical Interpretation

Azido‐copper(II) and ‐copper(I) complexes of 1‐alkyl‐2‐[(o‐thioalkyl)phenylazo]imidazole (SRaaiNR′) have been prepared and studied. Complex 2 [Cu(SRaaiNR′)(μ1,1‐N3)(N3)]2 dimerises via end‐to‐end (μ1,3)‐N3 to form a tetrameric structure. Azido‐copper(I) complexes of the ligands are obtained as MeOH‐bridged dimers, [Cu(SRaaiNR′)(N3)(μ‐OHMe)]2 (3). The electronic spectra suggest that a small reorganisation energy (0.08 eV) is associated with the change in electronic configuration, structure and oxidation state from CuII to CuI. Redox interconversion, CuII ↔ CuI, [Cu(SMeaaiNMe)(μ‐N3)(N3)]2 (2a) ↔ [Cu(SMeaaiNMe)(N3)(μ‐OHCH3)]2 (3a), has been performed in one case. The tetranuclear complex shows ferromagnetic and antiferromagnetic interactions. The spectra, redox chemistry and magnetism are explained by DFT studies.