Metal complexes of azomethine compounds bearing an azo group in the amine fragment: Syntheses, structures, and properties

Abstract

New complexes of Cu(II), Co(II), Ni(II), and Zn(II) with 1 phenyl 3 methyl 4 (4 phenyla zophenylaminomethylene)pyrazol 5 one (HL 1 ) and 1 phenyl 3 methyl 4 [4 methyl 2 (4 methylpheny lazo)phenylaminomethylene]pyrazol 5 one (HL 2 ) are synthesized using chemical and electrochemical methods and characterized by IR spectroscopy, 1 H NMR spectroscopy, X ray absorption spectroscopy, X ray diffraction analysis, and magnetic measurements. All complexes are mononuclear. The structures of HL 2 and related cobalt complex are determined by X ray diffraction analysis (CIF files CCDC nos. 1028957 and 1035847, respectively).

XAS Diagnostic of the Photoactive State in Co(II) Azobenzene Complex in Organic Solvents

“…The increased interest in this complex is due to its structure. In accordance with the results of single-crystal XRD, [5] the used ambidentate ligands occupy three crystallographic sites near the central metal atom, unlike bidentate ligands in previously studied complex bis{1-phenyl-3methyl-4-[4-methyl-2-(4-methyl-phenylazo)phenylamino-methylene]pyrazol-5-onate}cobalt(II) (II) containing an azo group in the para-positions of the amine fragment of ligand [5] (Scheme 1). The elongated bonds between the cobalt ion and the nitrogen atoms of the azobenzene groups (2.2510(14) Å, 2.2889(15) Å) indicate the possibility of their dissociation as a result of light irradiation.…”

“…The final state (blue experimental spectrum) has a lower intensity of peak A, and the higher intensity of peak B and peak C shifted to higher energies. This tendency is similar to the changes between octahedral and tetrahedral Co(II) species, [5] indicating a decrease of the cobalt coordination number in DMF.…”

“…high spin (HS) Co(II) 6-coordinated (complex I) and 4-coordinated complex phenylaminomethylene]pyrazol-5-onate}cobalt(II) containing an azo group in para-positions of the amine fragment [5] (see Scheme 1). XANES spectrum for the tetrahedral complex II has a smaller intensity of peak A, stronger peak B intensity, and the peak C shifted to the higher energies.…”

“…To further investigate the crystalline Co complex I structure and solvated forms in DMF and acetonitrile, we measured a series of reference samples characterized by different Co valence, spin state and coordination number. Pair (b) of spectra in figure 3 shows Co K‐edge XAS measured for the crystalline high spin (HS) Co(II) 6‐coordinated (complex I) and 4‐coordinated complex II ‐ bis{1‐phenyl‐3‐methyl‐4‐[4‐methyl‐2‐(4‐methyl‐phenylazo)phenylaminomethylene]pyrazol‐5‐onate}cobalt(II) containing an azo group in para ‐positions of the amine fragment [5] (see Scheme 1). XANES spectrum for the tetrahedral complex II has a smaller intensity of peak A, stronger peak B intensity, and the peak C shifted to the higher energies.…”

Study of E/Z isomerization of (arylamino)methylidenefuran‐2(3H)‐ones by 1H, 13C, 15N spectroscopy and DFT calculations in different solvents

“…Derivatives containing enamine moiety can be easily incorporated into methylene‐active substrates using an orthoester and an amine under mild conditions . The enamine derivatives of furan‐2‐ones may be of interest not only for the investigation of their properties but also for studying of the Z/E‐ tautomeric equilibrium, complexation with transition metal ions and the creation molecular switches. The first and the only example of the series was described earlier .…”