Synthesis, structures, and spectral properties of biomimetic azomethine metal chelates with chromophores CuN2S2, CuN2O2, and CuN2Se2.: Crystal structure of bis[4-(benzyl)aldimino-3-methyl-1-phenyl-5-pyrazolothiolato]copper(II)

Copper(ii) chelates of composition CuL2 were synthesized based on 4-aminomethylene derivatives of 5-thiopyrazoles (LH). The complexes were studied by UV, IK, ESR, and EXAFS spectroscopy, magnetochemistry, and X-ray diffraction analysis. The coordination polyhedra in the complexes are pseudotetrahedra or octahedra of the types CuN2S2 or CuN4S2, respectively, which are distorted due to the Jahn-Teller effect. The UV and ESR spectra of copper chelates with a six-coordinate metallocycle formed by the N and S atoms of the azomethine ligand and the nitrogen atom of the quinoline substituent (R) of the C=N-R fragment are most similar to the spectra observed for metals involved in the active centers of natural metalloenzymes ("blue" copper proteins).