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)
Abstract
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.
Citation
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
Publication
Inorganic Chemistry
Status
Peer reviewed
ISSN
0020-1669Type
Journal article
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