Spin State of the Cobalt(II) Complex with N,N'-Disubstituted 2,6-Bis(pyrazol-3-yl)pyridine

The reaction of a new N,N'-disubstituted 2,6-bis(pyrazol-3-yl)pyridine ligand (L) with Co(ClO4)2·6H2O gave cobalt(II) complex [Co(L)2](ClO4)2 (I), which was characterized by elemental analysis, mass spectrometry, NMR spectroscopy, and X-ray diffraction (CIF file CCDC no. 2121030). According to the Evans methods, NMR spectroscopy, and analysis of the temperature dependence of the NMR spectra, which are used to identify the spin state of paramagnetic compounds in solution, the cobalt(II) ion in complex I occurs in the high-spin state and does not undergo temperature-induced spin transition in the 235–345 K range.