TiCl4 Dissolved in Ionic Liquid Mixtures from Аb Initio Molecular Dynamics Simulations

Abstract

To gain a deeper understanding of the TiCl4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]−, chloride [Cl]− both with and without water and titanium tetrachloride TiCl4. Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl4 not only compete with each other to interact mainly with [Cl]−, which strongly influences the cation-[BF4]− interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl4. Overall, the polar network of the IL mixture collapses by including water and TiCl4. In the case of [Cl]− chloride enters the water continuum, while [BF4]− remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network.

Ionic Liquid-Based Low-Temperature Synthesis of Crystalline Ti(OH)OF·0.66H2O: Elucidating the Molecular Reaction Steps by NMR Spectroscopy and Theoretical Studies

“…The main goal of our investigations was to get insight into the reaction mechanisms of the IL-based synthesis of Ti(OH)OF• 0.66H 2 O, especially the role of the BF 4 − anion and the formation of Ti complexes, on the basis of NMR spectra. To understand the interactions of the reactants with each other, the composition of mixtures of the involved compounds was systematically varied, and these solutions were subjected to 1 H, 13 C, 19 F, and 11 B NMR measurements. A scheme showing all measured solutions and the questions we tried to answer with different NMR measurements can be found in the Supporting Information (SI) (see Scheme S1).…”

“…In the past, NMR spectroscopy has already been successfully used to investigate IL-based syntheses. 13 Saihara et al investigated the hydrolysis process of the IL N,N-diethyl-Nmethyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEME BF 4 − ) in the presence of water by means of 19 F and 11 B NMR measurements. 14 They found that during the hydrolysis of BF 4 − , HF is generated and reacts with the surrounding glass container since SiF 6 2− was detected in the 19 F NMR spectrum.…”

“…− and a Ti complex, e.g., Ti(H 2 O) y (OH) 6−y y−2 . Hence, in the present study, we conducted 1 H, 13 C, 19 F, and 11 B NMR measurements on solutions containing different mixtures of the used reactants with the goal to elucidate intermediate products and interactions present in the solutions, to shed further light on the hydrolysis mechanism of BF 4 − in the mixture with Ti complexes. Since the heating step is crucial for the synthesis of Ti(OH)OF•0.66H 2 O, additional NMR measurements were performed on solutions heated in situ to 95 °C (standard reaction conditions, see Scheme 1).…”

Chemistry Dissolved in Ionic Liquids. A Theoretical Perspective

“…Traditionally, ionic liquids (and DESs) have been studied computationally mainly from classical molecular dynamics simulations based on force fields. − Car–Parrinello or Born–Oppenheimer ab initio molecular dynamics (AIMD) simulations based on the explicit description of the electronic structure concerning ionic liquids , and deep eutectic solvents ,− also appeared in the literature. Many contributions and clarifications came from static quantum chemical calculations. − As usual in static quantum chemistry, density functional theory (DFT) serves as workhorse for many calculations; , however, different methods were applied as well. − Polarizable force fields in all forms receive always special attention because they overcome many problems of traditional MD simulations. − …”

“…8 Traditionally, ionic liquids (and DESs) have been studied computationally mainly from classical molecular dynamics simulations based on force fields. 9−22 Car−Parrinello or Born−Oppenheimer ab initio molecular dynamics (AIMD) simulations 23 based on the explicit description of the electronic structure concerning ionic liquids 24,25 and deep eutectic solvents 8,26−30 also appeared in the literature. Many contributions and clarifications came from static quantum chemical calculations.…”