Comparative studies of vibrational properties and phase transitions in metal-organic frameworks of [NH4][M(HCOO)3] with M = Mg, Zn, Ni, Fe, Mn

Room temperature experimental infrared (IR) and Raman spectra of [NH4][M(HCOO)(3)] compounds with M = Mg, Zn, Ni, Fe, Mn were analyzed in order to propose the assignment of the experimental bands to the respective internal and lattice modes. We also report temperature-dependent IR studies of [NH4][Ni (HCOO)(3)] and [NH4][Fe(HCOO)(3)] in the temperature range 5-295 K, and compare them with the previously reported data for the Zn and Mg analogs. The temperature-dependent data provide deeper insight into mechanism of the phase transition and relationship between the phase transition temperature and chemical composition of the studied compounds. (C) 2015 Elsevier B.V. All rights reserved.