Crystal growth, crystal structure determination, and computational studies of a new mixed (NH4)2Mn1–xZnx(SO4)2(H2O)6 Tutton salt

Abstract

Tutton salts have been extensively explored in recent decades due to their attractive physical and chemical properties, which make them potential candidates for thermochemical heat storage systems and optical technologies. In this paper, a series of new mixed Tutton salts with the chemical formula (NH4)2Mn1–xZnx(SO4)2(H2O)6 is reported. Crystals are successfully grown by the solvent slow evaporation method and characterized by powder X-ray diffraction (PXRD) with Rietveld refinement. In particular, the crystal structure of the mixed (NH4)2Mn0.5Zn0.5(SO4)2(H2O)6 crystal is solved through PRXD data using the DICVOL06 algorithm for diffraction pattern indexing and the Le Bail method for lattice parameter and spatial group determination. The structure is refined using the Rietveld method implemented in TOPAS® and reported in the Cambridge Structural Database file number 2104098. Moreover, a computational study using Hirshfeld surface and crystal void analyses is conducted to identify and quantify the intermolecular interactions in the crystal structure as well as to determine the amount of free space in the unit cell. Furthermore, 2D-fingerprint plots are generated to evaluate the main intermolecular contacts that stabilize the crystal lattice. Density functional theory is employed to calculate the structural, thermodynamic, and electronic properties of the coordination [Zn(H2O)6]2+ and [Mn(H2O)6]2+ complexes present in the salts. Molecular orbitals, bond lengths, and the Jahn–Teller effect are also discussed. The findings suggest that in Mn-Zn salts several properties dependent on the electronic structure can be tuned up by modifying the chemical composition.

Assessing the Novel Mixed Tutton Salts K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 for Thermochemical Heat Storage Applications: An Experimental–Theoretical Study

“…Secondly, electronegativity χ-metals with greater electronegativity (χ(Ni) = 1.91 and (χ(Cu) = 1.90) exhibit greater occupations of divalent sites due to the greater tendencies to attract electrons when compared to Mn (χ(Mn) = 1.55). Thirdly, intermolecular interactions-the Mn(II) hexa-aqua complexes are highly unstable; however, in some Tutton salts, this metal presents stability due to hydrogen bonds, as is true in the case of crystals of (NH 4 ) 2 Mn(SO 4 ) 2 (H 2 O) 6 [44] and (NH 4 ) 2 Mn 0.5 Zn 0.5 (SO 4 ) 2 (H 2 O) 6 [29]. On the other hand, weak interactions that destabilize [Mn(H 2 O) 6 ] 2+ complexes, such as ion-dipole and dispersion forces, are also observed in the atomic packing of potassium Tutton salts.…”

“…Several mixed Tutton salts, such as K 2 Ni x Co 1−x (SO 4 ) 2 (H 2 O) 6 [28], (NH 4 ) 2 Ni x Co 1−x (SO 4 ) 2 (H 2 O) 6 [15], (NH 4 ) 2 Mn 1−x Zn x (SO 4 ) 2 (H 2 O) 6 [29], K 2 Zn x Mg 1−x (SO 4 ) 2 (H 2 O) 6 [30], and (NH 4 ) 2 Ni x Cu 1−x (SO 4 ) 2 (H 2 O) 6 [31], have been explored as materials for ultraviolet light filters and solar-blind devices. Recently, there has been great interest in thermochemical applications, where materials can store energy in the heat form by heating water [2,3,[32][33][34].…”

Synthesis, Thermal Analysis, Spectroscopic Properties, and Degradation Process of Tutton Salts Doped with AgNO3 or H3BO3

“…Neto et al 19 concluded in a new and interesting study that these crystals can be applied in thermochemical systems for thermal energy storage and also evaluated the empty spaces present in the unit cells of their crystals through electronic density isosurfaces, showing that high percentage of empty spaces can cause a decrease in the energy of interactions affecting physicochemical parameters such as solubility, dissolution, and hardness of crystalline structures. On the other hand, these empty spaces can be filled by dopants in order to strengthen these intermolecular interactions in order to increase, for example, the thermal stability of the crystals.…”