Unusual physical and chemical properties of ionic liquids (ILs) open up prospects for various applications. We report the first observation of density/rigidity heterogeneities in a series of ILs near the glass transition temperature ( T) by means of pulse electron paramagnetic resonance (EPR). Unprecedented suppression of molecular mobility is evidenced near the glass transition, which is assigned to unusual structural rearrangements of ILs on the nanometer scale. Indeed, pulse and continuous wave EPR clearly indicate the occurrence of heterogeneities near T, which exist in a rather broad temperature range of ∼50 K. The two types of local environments are evidenced, being drastically different by their stiffness. The more rigid one suppresses molecular mobility, whereas the softer one instead promotes diffusive molecular rotation. Such properties of ILs near T are of general importance; moreover, the observed density/rigidity heterogeneities controlled by temperature might be considered as a new type of tunable reaction nanoenvironment.

Polyfluorinated phenyl(dihydroxy)boranes C 6 H 5-n F n B-(OH) 2 (n ϭ 3 Ϫ 5) underwent hydrodeboration (formal replacement of the (dihydroxy)boryl group by hydrogen) in the presence of bases (MeOH, 33 % H 2 OϪMeOH, KOH (1 equiv.)/33 % H 2 OϪMeOH, pyridine and 9 % D 2 OϪpyridine) and formed the fluoroaromatic compounds ArH or ArD, respectively. The rate of Polyfluororganische Bor-Sauerstoff Verbindungen. 2 [1] Die Hydrodeborierung von Polyfluorphenyl(dihydroxy)boranen unter basischen Bedingungen.Inhaltsübersicht. Polyfluorierte Phenyl(dihydroxy)borane C 6 H 5-n F n B-(OH) 2 (n ϭ 3 Ϫ 5) unterliegen in Gegenwart von Basen (MeOH, 33 % H 2 OϪMeOH, KOH (1 Äquiv.)/33 % H 2 OϪMeOH, Pyridin und 9 % D 2 OϪPyridin) einer Hydrodeborierungsreaktion (formaler Ersatz der (Dihydroxy)borylgruppe durch Wasserstoff) und bil-* Prof. reaction depends on the number of fluorine atoms in the phenyl group and on the position of the fluorine atoms, relative to the B(OH) 2 substituent.

Intriguing nanostructuring anomalies have been recently observed in imidazolium ionic liquids (ILs) near their glass transition points, where local density around a nanocaged solute progressively grows up with temperature. Herewith,...

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Currently, the chemistry of organofluorine compounds is a leading and rapidly developing area of organic chemistry. Fluorine present in a molecule largely determines its specific chemical and biological properties. This thematic issue covers the trends of organofluorine chemistry that have been actively developed in Russia the last 15 – 20 years. The review describes nucleophilic substitution and heterocyclization reactions involving fluorinated arenes and quinones and skeletal cationoid rearrangements in the polyfluoroarene series. The transformations involving CF3-substituted carbocations and radical cations are considered. Heterocyclization and oxidative addition reactions of trifluoroacetamide derivatives and transformations of the organic moiety in polyfluorinated organoboranes and borates with retention of the carbon – boron bond are discussed. Particular attention is devoted to catalytic olefination using freons as an efficient synthetic route to fluorinated compounds. The application of unsymmetrical fluorine-containing N-heterocyclic carbene ligands as catalysts for olefin metathesis is demonstrated. A variety of classes of organofluorine compounds are considered, in particular, polyfluorinated arenes and 1,2-diaminobenzenes, 1-halo-2-trifluoroacetylacetylenes, α-fluoronitro compounds, fluorinated heterocycles, 2-hydrazinylidene-1,3-dicarbonyl derivatives, imines and silanes. The potential practical applications of organofluorine compounds in fundamental organic chemistry, materials science and biomedicine are outlined. The bibliography includes 1019 references.

Unusual physicochemical properties of ionic liquids (ILs) open vistas for a variety of new applications. Herewith, we investigate the influence of microviscosity and nanostructuring of ILs on spin dynamics of the dissolved photoexcited molecules. We use two most common ILs [Bmim]PF6 and [Bmim]BF4 (with its close analogue [C10mim]BF4) as solvents and photoexcited Zn tetraphenylporphyrin (ZnTPP) as a probe. Time-resolved electron paramagnetic resonance (TR EPR) is employed to investigate spectra and kinetics of spin-polarized triplet ZnTPP in the temperature range 100-270 K. TR EPR data clearly indicate the presence of two microenvironments of ZnTPP in frozen ILs at 100-200 K, being manifested in different spectral shapes and different spin relaxation rates. For one of these microenvironments TR EPR data is quite similar to those obtained in common frozen organic solvents (toluene, glycerol, N-methyl-2-pyrrolidone). However, the second one favors the remarkably slow relaxation of spin polarization, being much longer than in the case of common solvents. Additional experiments using continuous wave EPR and stable nitroxide as a probe confirmed the formation of heterogeneities upon freezing of ILs and complemented TR EPR results. Thus, TR EPR of photoexcited triplets can be effectively used for probing heterogeneities and nanostructuring in frozen ILs. In addition, the increase of polarization lifetime in frozen ILs is an interesting finding that might allow investigation of short-lived intermediates inaccessible otherwise.

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A general preparative procedure for polyfluorinated aryl-(dihydroxy)boranes C 6 H 5-n F n B(OH) 2 (n ϭ 3 Ϫ 5) is described. Polyfluorinated aryl(dihydroxy)boranes are easily dehydrated to the corresponding tri(aryl)boroxins (C 6 H 5-n F n BO) 3 by thermal or chemical treatment. The property of the acids C 6 H 5-n F n B(OH) 2 to condensate depends on the number and on the position of the fluorine atoms in the aryl group. Examples of both classes of boron Polyfluororganische Bor-Sauerstoff Verbindungen. 1 Polyfluorierte Aryl(dihydroxy)borane und Tri(aryl)boroxineInhaltsübersicht. Es wird ein allgemeiner Weg für die Darstellung polyfluorierter Aryl(dihydroxy)borane beschrieben. Polyfluorierte Aryl(dihydroxy)borane lassen sich thermisch und chemisch leicht dehydratisieren und gehen dabei in die entsprechenden Tri(aryl)boroxine über. Die Neigung zur Kondensation hängt sowohl von der