title: Interaction of copper with dinitrogen tetroxide in 1-butyl-3-methylimidazolium-based ionic liquids.
abstract: Ionic liquids that are stable toward oxidation and nitration and are based on the 1-n-butyl-3-methylimidazolium cation (BMIm+) can be used as solvents and reaction media for copper dissolution in liquid dinitrogen tetraoxide N2O4. The ionic liquid not only favors the dissociation of N2O4into NO+and NO3-, but also takes part in the formation of different crystalline products. Thus, NO[BF4], NO[Cu(NO3)3] and (BMIm)2[Cu2(CF3COO)6] were prepared using (BMIm)A, A-= [BF4]-, (CF3SO2)2N-, CF3COO-, respectively. The formation of a certain product is determined by the nature of the anion A-and the relative solubility of the reaction products in the ionic liquid. Crystals of NO[BF4] were also prepared directly from a mixture of N2O4and BMImBF4. According to XRD single-crystal structure analysis, the structure of NO[BF4] consists of tetrahedral [BF4]-anions and nitrosonium NO+cations; the formation of these ions prove the heterolytic dissociation of N2O4dissolved in the ionic liquid. The crystal structure of the earlier unknown binuclear copper trifluoroacetate (BMIm)2[Cu2(CF3COO)6] were determined by X-ray diffraction. The peculiarity of this dimer compared to the majority of known dimeric copper(ii) carboxylates is the unusually long CuCu distance (3.15 Å), with Cu(ii) ions demonstrating an atypical coordination of a distorted trigonal bipyramid formed by five O atoms of five trifluoroacetate groups.
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia.
authors.forename: I V
authors.initials: IV
authors.lastname: Morozov
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia.
authors.forename: E B
authors.initials: EB
authors.lastname: Deeva
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia.
authors.forename: T Yu
authors.initials: TY
authors.lastname: Glazunova
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia.
authors.forename: S I
authors.initials: SI
authors.lastname: Troyanov
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia and National University of Science and Technology MISiS, Leninsky prosp. 4, Moscow, Russia. lmk@ioc.ac.ru.
authors.forename: F I
authors.initials: FI
authors.lastname: Guseinov
authors.affiliation: Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, 1-3, Moscow 119991, Russia and National University of Science and Technology MISiS, Leninsky prosp. 4, Moscow, Russia. lmk@ioc.ac.ru.
authors.forename: L M
authors.identifier: http://orcid.org/0000-0003-2312-3583
authors.initials: LM
authors.lastname: Kustov