Hydrothermal synthesis, crystal structure, spectroscopic and magnetic properties of Mn-4(H2O)(3)(SeO3)(4) and Mn-3(H2O)(SeO3)(3)

摘要

Two new manganese(II) selenites with the formula Mn-4(H2O)(3)(SeO3)(4) (1) and Mn-3(H2O)(SeO3)(3) (2) have been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structure of both compounds has been solved from single crystal X-ray data. The structures consist of a three-dimensional framework formed by MnO6 octahedra and (SeO3)(2-) selenite anions with trigonal pyramidal geometry. Compound 1 shows the existence of sheets constructed from zig-zag chains linked to MnO6 octahedra. Compound 2 exhibits zig-zag chains formed by edge-sharing dimeric octahedra which are interconnected by Mn2O10 octahedra. The IR and Raman spectra show the characteristic bands of the selenite anion. Studies of luminescence at 6.0 K and diffuse reflectance spectroscopy have been carried out for both compounds. The Dq and Racah parameters are Dq = 715, B = 705 and C = 3420 cm(-1) for 1 and Dq = 710, B = 700 and C = 3425 cm(-1) for 2. The ESR spectra are isotropic with a g-value of 2.00(1), which remains unchanged with variation in temperature. Magnetic measurements indicate the presence of antiferromagnetic interactions in both phases. [References: 53]