Magnetic properties of the anion-radical salts [M(bipy)3](TCNQ)4·X, where M = Co, Ni, Zn and X = H2O or (CH3)2CO

Abstract

An anion-radical salt (ARS) [Co(bipy)3](TCNQ)4·H2O was synthesized and its crystal structure was resolved. The experimental investigation of [Co(bipy)3](TCNQ)4·H2O and two ARS with similar crystal structure [Zn(bipy)3](TCNQ)4·H2O and [Ni(bipy)3](TCNQ)4·(CH3)2CO by the measurement of the temperature dependence of magnetic susceptibility at temperature from 1.8 K to 300 K, the field dependence of magnetization up to 7 T at different temperatures and EPR spectra in temperature range from 2 K to 300 K was performed. [Zn(bipy)3](TCNQ)4·H2O was used to estimate the contribution of the TCNQ radicals to the magnetic moment. In result, the compound [Co(bipy)3](TCNQ)4·H2O was characterized by the presence of Co2+ ions in spin-admixed state and low-temperature susceptibility, magnetization and specific heat of [Ni(bipy)3](TCNQ)4·(CH3)2CO was shown to be dominated by the contribution of single-ion anisotropy of Ni2+ ions.