Crystallographic insights into the behavior of highly acidic metal cations in ionic liquids from ractions of titanium tetrachloride with [1-butyl-3-methylimidazolium][X] ionic liquids (X = chloride, bromide, tetrafluoroborate)
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Highly charged metal ions are difficult to investigate in weakly coordinating ionic liquids (ILs) because of the insolubility of their solid forms, but the molecular liquid TiCl4 offers a way to react tetravalent metal ions in an IL. Reactions of TiCl4 with 1-butyl-3-methylimidazolium ([C4mim]+)-based ILs containing chloride or bromide lead to mixtures of highly metastable amorphous solids and small amounts of crystalline chlorotitanate salts including [C4mim]2[TiCl6] and two polymorphs of [C4mim]2[Ti2Cl10] in a manner not well correlated with stoichiometry or anion identity. The reaction of TiCl4 with [C4mim][BF4] yields crystals of the mixed fluoro-chloro complex [C4mim]2[Ti4F6Cl12], indicating spontaneous reaction of the IL ions to generate HF in situ. These unusual behaviors are explained in terms of the exceptionally high acidity of Ti4+ and the unusual behavior of TiCl4 among metal halides as a nonpolar molecular compound.
Mishra , M K , Kelley , S P , Dilip , M , Vaid , T P , Cordes , D B , Griffin , S T & Rogers , R D 2019 , ' Crystallographic insights into the behavior of highly acidic metal cations in ionic liquids from ractions of titanium tetrachloride with [1-butyl-3-methylimidazolium][X] ionic liquids (X = chloride, bromide, tetrafluoroborate) ' , Inorganic Chemistry , vol. 58 , no. 3 , pp. 1764-1773 . https://doi.org/10.1021/acs.inorgchem.8b00524
Copyright © 2019 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1021/acs.inorgchem.8b00524
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