Nuclear Resonance Determination of the Magnetic Space Group of MnCl2·2H2O

The Cl and H nuclear magnetic resonance spectra have been used to study magnetic ordering in MnCl₂·2H₂O. It was found that the material orders antiferromagnetically with a Néel temperature of 6.8°K. The magnetic space group deduced from the Cl data was shown to be $C_{\text{2c}}\text{2\hspace{0.17em}/\hspace{0.17em}m}$ . The proton resonance data were shown to substantiate the magnetic space group assignment. The compound is isostructural with CoCl₂·2H₂O. Both compounds contain linear chains of magnetic ions running along the $c$ axis. However, in the Mn compound the chains are antiferromagnetically coupled while in the Co compound they are ferromagnetically coupled.