X-Ray Diffraction Study of MgCl₂ in Methanol

Abstract

The structure of a concentrated solution of MgCl2 in methanol has been studied by X-ray diffraction. The parameters for the ion-solvent interactions are in good agreement with those found in aqueous solutions. Both for Mg2+ and Cl- the solvate shells are composed of 6 methanol molecules. An average octahedral arrangement of OH groups in the solvate shells of magnesium is probable. Octahedral symmetrical positions for CH3 groups proved to be unlikely

Genesis of MgCl2‐based Ziegler‐Natta Catalysts as Probed with Operando Spectroscopy

“…For each adduct we have defined six temperature steps, corre-sponding to the most relevant weight losses as determined by TGA (colored dots in Figure 1), at which we have been collecting XRPD patterns and DR UV-Vis spectra, while the DRIFT spectra were collected continuously during the temperature ramp. In the case of MgCl 2 -6MeOH (part a), pattern 1, collected at room temperature, is characteristic of a solid solution in which both the Mg 2 + cations and the Cl À anions are surrounded by six alcohol molecules in the first solvation shell, [79,80] thus confirming the stoichiometry resulting from the TGA. In the case of MgCl 2 -6MeOH (part a), pattern 1, collected at room temperature, is characteristic of a solid solution in which both the Mg 2 + cations and the Cl À anions are surrounded by six alcohol molecules in the first solvation shell, [79,80] thus confirming the stoichiometry resulting from the TGA.…”

“…Figure 2 shows the evolution of the XRPD patterns during the dealcoholation of the MgCl 2 -6ROH adducts under N 2 flow at increasing temperatures. In the case of MgCl 2 -6MeOH (part a), pattern 1, collected at room temperature, is characteristic of a solid solution in which both the Mg 2 + cations and the Cl À anions are surrounded by six alcohol molecules in the first solvation shell, [79,80] thus confirming the stoichiometry resulting from the TGA. In this sense, the structure of the solid MgCl 2 -6MeOH adduct can be considered as an arrangement of discrete octahedra with Mg 2 + ions in the centers and MeOH molecules in the corners, and with the chloride ions excluded from the Mg 2 + coordination sphere as counterions.…”

MD Simulation Studies of Selective Solvation in Methanol−Water Mixtures: An Effect of the Charge Density of a Solute

“…Such coincidence is in good agreement with the neutron scattering data. 38,40,41 The Cl --O distances of 0.31 and 0.33 nm were reported for aqueous and methanol solutions, respectively, whereas the separation between Cland hydrogen in these solutions was found to be 0.23 and 0.22 nm, Figure 2. Binding energies of the ion-water (solid lines) and ionmethanol (dashed) complexes versus the ion-oxygen distance calculated for the pair potential parameters from Table 1.…”

“…This shorter distance is in better accord with the experimental data. [38][39][40][41] In aqueous solution, the broad first peak of g Cl -O is noticeably worse pronounced compared to that obtained with the ab initio potentials. 17 The running integration number shows no plateau, and estimation of a hydration number is rather ambiguous.…”

“…38 In methanol solution the solvation number n M ∼ 6-7 for both types of the potentials is in good agreement with the experimental value n M ∼ 6. 41 The LJ-type potentials 20-25 are known to neglect non-Coulomb interaction between an ion and the hydroxyl hydrogen. Much better accord with experiment obtained for the methanol solution indicates that neglect of these terms is less important in methanol than in aqueous systems for which the ab initio potentials 17 occur to be more adequate.…”