Temperature-dependent IR and Raman studies of metal–organic frameworks [(CH3)2NH2][M(HCOO)3], M = Mg and Cd

• Temperature-dependent Raman scattering and IR measurements for [(CH3)2NH2][Mg(HCOO)3] and [(CH3)2NH2][Cd(HCOO)3] were performed.
• The phase transition in Mg-compound at 270 K is driven by ordering of the dimethylammonium cations.

Two metal–organic frameworks of [(CH3)2NH2][M(HCOO)3], where M = Mg and Cd, have been investigated by temperature-dependent IR and Raman methods in order to determine the nature of the phase transition. Our results indicate that phase transition in the Mg-compound is driven by ordering of the dimethylammonium cations. Additional X-ray diffraction and spectroscopic studies on Cd-compound as the function of temperature reveal that this compound does not undergo any structural phase transition. We attribute this behavior to the large size of the cavity occupied by the dimethylammonium cations and thus weak hydrogen bonding between these cations and formate ions.

Temperature-dependent IR and Raman studies of metal–organic frameworks [(CH3)2NH2][M(HCOO)3], M = Mg and Cd.Figure optionsDownload as PowerPoint slide