3.2. Solution Magnetic Susceptibility Measurements

The solution state molar magnetic susceptibility (χm) of 1, 2(ClO₄)₂ and 3(ClO₄)₂ was measured according to the Evans method [53,54]. This involves the placement of a coaxial insert containing sample solution (0.010 M) into a standard 5 mm NMR tube containing only solvent. CD₃CN containing one drop of benzene as internal reference was used as the solvent throughout. Based on the chemical shift difference of the benzene internal reference between inner and outer tubes, values of molar magnetic susceptibility (χm) and magnetic moment (μeff) were calculated using the equations shown below [66,67]:

where χm = molar magnetic susceptibility of the sample (m³ mol⁻¹); △f = difference of the chemical shift (Hz) between the internal references of inner and outer tubes; f = operating frequency of the NMR spectrometer (Hz); c = concentration of the metal complex (mol dm⁻³); T = probe temperature of the measurement (K).