Proton and Chlorine Nuclear Magnetic Resonance in Antiferromagnetic MnCl2·4H2O

The magnetic structure of the antiferromagnetic phase of Mn${\mathrm{Cl}}_2$·4${\mathrm{H}}_2$O has been examined using proton and chlorine NMR. By combining observations on the symmetry and number of proton internal magnetic fields with x-ray and neutron-diffraction data, one is led to three possible magnetic structures. However, only one of these ($\frac{P{2}_1}{a^{\prime }}$) predicts fields at the proton sites whose orientation and magnitude is in reasonable agreement with the experimentally observed fields. The chlorine resonance data corroborate the proton-resonance results and provide information on the transferred hyperfine interaction.