Solvation of Manganese(III) Ion in Water and in Ammonia

Abstract

In this work, we have studied the solvation of manganese­(III) ion in water and in ammonia using three levels of theory: MP2, MN15, and ωB97XD associated with the aug-cc-pVDZ basis set. The studied systems are constituted of Mn3+(H2O)6 and Mn3+(NH3)6 in gas and solvent phases as well as Mn3+(H2O)18 and Mn3+(NH3)18 in the gas phase. Four aspects of the solvation of manganese­(III) ion have been examined for the aforementioned systems at the three levels of theory. First, we started by locating the Jahn–Teller elongated and compressed configuration in Mn3+(H2O)6 and Mn3+(NH3)6. Second, we calculated the spin state energies and the spin state free energies for temperatures ranging from 50 to 400 K to look at possible spin crossover in the studied systems. Third, we carried out a quantum theory of atoms in molecules (QTAIM) analysis, and we determined the ionic radii of manganese­(III) ion in water and in ammonia. Fourth, we calculated the solvation free energies and the solvation enthalpies of manganese­(III) ion in water and in ammonia using the cluster continuum solvation model. For these four aspects of the solvation of manganese­(III) ion, most of the reported properties are provided in this work for the first time. We particularly found that the calculated solvation enthalpy of the manganese­(III) ion in water is in good agreement with an experimental estimate.

Unique Hexanuclear Mixed Bimetallic MnIII2NiII4 Complex Possessing Both Jahn–Teller Tetragonally Elongated and Compressed MnIII Ions: Spin Frustration

“…Our calculations determine the following ground state electronic configuration for the JT compressed Mn1 ion: (d xy ) 1 , (d yz ) 1 , (d xz ) 1 , (d x 2 –y 2 ) 1 , and (d z 2 ) 0 , and for the JT elongated Mn2 ion: (d xy ) 1 , (d yz ) 1 , (d xz ) 1 , (d z 2 ) 1 , and (d x 2 – y 2 ) 0 (see Figure a). These configurations support the axially elongated Mn ion possessing the empty d x 2 – y 2 orbital, resulting in the zfs parameter D < 0, , , and in the axially compressed Mn ion possessing the empty d z 2 orbital, resulting in D > 0, same as previously reported. − , Furthermore, in the elongated case, the energy gap between the empty magnetic orbital and other orbitals is large, but it is modest in the compressed case.…”

“…The Mn–O/N bond lengths of Mn1 center of 1 clearly suggest that Mn1 with O 6 donor set center has undergone a JT tetragonal compression − (Mn–O axial 1.867/1.864 Å; Mn–O equatorial 2.182, 2.021, 1.993, 2.139 Å) while the Mn2 center with a N 2 O 4 donor set possesses a JT Mn–N bond elongation (Mn–N axial 2.323/2.347 Å; Mn–O equatorial 1.881, 1.881, 1.967, 1.948 Å) (Table ). ,, This structural feature is unprecedented in the literature, although there have been reports of a plethora of Mn and Mn–Ni complexes to date.…”

“…The Mn III ion may undergo either JT elongation or JT compression of the axial bond lengths, which has significant and captivating effects on its spin relaxation at low temperatures. The occurrence of the former phenomenon is quite frequent due to the population of d z 2 orbital, while the number of the latter contains only a handful of examples in Mn III complexes. − It has been established by spectroscopic, magnetic studies, and theoretical calculations that Mn III ions having tetragonal JT elongation contribute negative D (zero-field splitting; zfs) while Mn III ions with JT axial compression possess positive D , which is remarkable from the point of view of molecular magnetism ,, having a significant implication on the physical properties of complexes containing Mn III ions. SMM behavior of Mn III -containing complexes largely depends on the negative D value of Mn III ions .…”

Quantum cluster equilibrium theory applied to liquid ammonia

“…The ABCluster parameters used to generate clusters successfully explored molecular systems like thiophene, ethanol, acetonitrile, and furan. 11,[39][40][41] From the generated geometries, the 10 structures with the lowest energies were automatically set aside to be optimized later on at the chosen level of theory. In addition, all other geometries that differed from the 10 selected ones were also selected for further optimizations.…”

“…9,10 Since the first works using the QCE theory, some improvements have been made for more accurate results. 11 We can enumerate the treatment of binary systems, 12,13 the anharmonicity effects, 14 the modified partition function by treating the low energy vibration frequencies as hindered rotations as suggested by Grimme. 15,16 Besides, a new method of determining some parameters of the QCE theory was developed by Kuo et al 17 and applied to liquid methanol.…”