Influence of Compression on Magnetic Properties of Nickel Chloride Coordination Compound with 3-Amino-4-Ethoxycarbonylpyrazole

Abstract

This study devotes the influence of uniaxial compression on electron paramagnetic resonance (EPR) spectra of a polycrystalline coordination compound of nickel chloride with 3-amino-4-ethoxycarbonylpyrazole (L). After exposure to uniaxial compression, approximately 3 % of the compound was shown to turn into a new state characterized by the singlet ground state. The gap between high-lying triplet state and the ground state is 0.018 eV that ensures the former is populated at room temperature according to the Boltzmann distribution. The EPR parameters for the nickel containing centers in the triplet state at room temperature were calculated: g || = 2.18(1), g ⊥ = 2.17(2), D = 1300(100) G, and E = 0. There are two assumptions about the nature of these centers. First, the influence of uniaxial compression is supposed to lead to a tetrahedral distortion of the octahedral environment of nickel ions. Second, the formation of the dimer nickel containing center is due to closing the terminal groups of the nearest polymer chains.