A new synthetic route, characterization and vibrational studies of manganese hypophosphite monohydrate at ambient temperature

The manganese hypophosphite monohydrate (Mn(H2PO2)2·H2O) was synthesized by using the energy saving method in acetone medium for controlling the exothermic process of H2 gas releasing. The thermal analysis (TG/DTG/DTA), atomic absorption spectrophotometry (AAS) and X-ray powder diffraction (XRD) were employed to characterize this compound. These methods confirm the formula of the title compound. The SEM data in this work agree well with the previously reported work. The vibrational behavior was studied by using the FTIR and FT Raman methods. The correlation field splitting analysis of H2O in Mn(H2PO2)2·H2O symbolized as C2v-C1-C2h5 and C2v-Ci-C2h5 suggested the number of vibrational modes to be: Γ(vib,H2O) = 3Ag + 3Bg + 3Au + 3Bu. While the case of hypophosphite anion can be suggested to exhibit 16 (infrared) [Au(8) + Bu(8)] and 18 Raman [Ag(9) + Bg(9)] bands which agree well with the observed FT IR spectra. However, the Raman spectra could not be fully identified. The coupling between these modes with the appropriate vibrations of neighboring species at each sites in the unit cell can further influence the vibrational spectra.