The work summarizes the data on currently known dimeric boron cluster anions with the general formula [B 20 H 18 ] 2− . Their preparation, structure, and the methods of structural modification are considered. The data on the reactivity of boron dimeric clusters in redox, substitution, complexation, and condensation reactions are presented. The isomerism of dimeric polyhedral boron cluster anions associated with the formation of substituted derivatives and coordination compounds is considered. The methods of reversible transformation of isomers in salts and coordination compounds in solutions and single crystals are discussed.

В работе обобщены сведения о димерных кластерных анионах бора общей формулы [B20H18]2–, известных на настоящий момент. Рассмотрены пути их получения, описано строение и способы структурной модификации. Представлены сведения о реакционной способности димерных кластеров бора в реакциях окисления/восстановления, замещения, комплексообразования и конденсации. Рассмотрены вопросы изомерии димерных полиэдрических кластерных анионов бора при образовании замещенных производных и комплексных соединений, способы обратимой трансформации изомеров в солях и комплексных соединениях в растворе и монокристаллах.

Novel hydrophobic ionic liquids (ILs) with tris(perfluoroalkyl)trifluorophosphate anions (e.g. [(C2F5)(3)PF3](-); FAP anion), the bis[bis(pentafluoroethyl)phosphinyl]imide (FPI) anion, the tetracyanoborate (TCB) anion, the tricyanofluoroborate (MFB) anion and the dicyanodifluoroborate (DDB) anion have been developed. The properties of these ionic liquids, i.e. their thermal and electrochemical stabilities as well as their viscosities, densities and refractive indices were studied and will be discussed. FAP ionic liquids are more hydrolytically stable and less viscous compared to ionic liquids with the hexafluorophosphate ([PF6](-)) anion. The hydrophobicity of ionic liquids with the cyano- and fluoroborate anions [BFx(CN)(4-x)](-) (x = 0-4) strongly decrease in the order: EMIM[B(CN)(4)] > EMIM[BF(CN)(3)] > EMIM[BF2(CN)(2)] > EMIM[BF3(CN)] similar to EMIM[BF4]; EMIM[BF3(CN)] as well as EMIM[BF4] are miscible with water. The lowest viscosity for all ionic liquids composed of the EMIM cation and weakly coordinating anions as the ones presented herein was observed for EMIM[BF2(CN)(2)] (11.1 mPa.s at 20 degrees C). (C) 2015 Elsevier B.V. All rights reserved.

This article traces curriculum developments in language teaching since the mid-1970s. The 1970s were chosen because they denote a time of massive global movement of immigration and expatriation that carried with it a profound impact on language education. The time frame also coincides with an awakening of research in sociolinguistics, discourse analysis, and second-language acquisition. The article places language learning against a backdrop of these research thrusts as well as against global political, economic, and technological forces. Key themes discussed are notions of doing and meaning, proficiency orientations; content-based language instruction; and immersion models for language acquisition.

Homoleptic octahedral, superelectrophilic sigma-bonded metal carbonyl cations of the type [M(CO)(6)](2+) (M = Ru, Os) are generated in the Bronsted-Lewis conjugate superacid HF/SbF(5) by reductive carbonylation of M(SO(3)F)(3) (M = Ru, Os) or OsF(6). Thermally stable salts form with either [Sb(2)F(11)](-) or [SbF(6)](-) as anion, just as for the previously reported [Fe(CO)(6)](2+) cation. The latter salts are generated by oxidative (XeF(2)) carbonylation of Fe(CO)(5) in HF/SbF(5). A rationale for the two diverging synthetic approaches is provided. The thermal stabilities of [M(CO)(6)][SbF(6)](2) salts, studied by DSC, range from 180 degrees C for M = Fe to 350 degrees C for M = Os before decarbonylation occurs. The two triads [M(CO)(6)][SbF(6)](2) and [M(CO)(6)][Sb(2)F(11)](2) (M = Fe, Ru, Os) are extensively characterized by single-crystal X-ray diffraction and vibrational and (13)C NMR spectroscopy, aided by computational studies of the cations. The three [M(CO)(6)][SbF(6)](2) salts (M = Fe, Ru, Os) crystallize in the tetragonal space group P4/mnc (No. 128), whereas the corresponding [Sb(2)F(11)](-) salts are monoclinic, crystallizing in space group P2(1)/n (No. 14). In both triads, the unit cell parameters are nearly invariant of the metal. Bond parameters for the anions [SbF(6)](-) and [Sb(2)F(11)](-) and their vibrational properties in the two triads are completely identical. In all six salts, the structural and vibrational properties of the [M(CO)(6)](2+) cations (M = Fe, Ru, Os) are independent of the counteranion and for the most part independent of M and nearly identical. Interionic C...F contacts are similarly weak in all six salts. Metal dependency is noted only in the (13)C NMR spectra, in the skeletal M-C vibrations, and to a much smaller extent in some of the C-O stretching fundamentals (A(1g) and T(1u)). The findings reported here are unprecedented among metal carbonyl cations and their salts.

As the first examples of homoleptic, sigma-bonded superelectrophilic metal carbonyl cations with tetrafluoroborate [BF(4)](-) as the counter anions three thermally stable salts of the composition [M(CO)(6)][BF(4)](2) (M = Fe, Ru, Os) have been synthesized and extensively characterized by thermochemical, structural, and spectroscopic methods. A common synthetic route, the oxidative carbonylation of either Fe(CO)(5) (XeF(2) as the oxidizer) or M(3)(CO)(12) (M = Ru, Os) (F(2) as the oxidizer) in the conjugate Bronsted-Lewis superacid HF/BF(3), was employed. The thermal behavior of the three salts, studied by differential scanning calorimetry (DSC) and gas-phase IR spectroscopy of the decomposition products, has been compared to that of the corresponding [SbF(6)](-) salts. The molecular structures of [M(CO)(6)][BF(4)](2) (M = Fe, Os) were obtained by single-crystal X-ray diffraction at 100 K. X-ray powder diffraction data for [M(CO)(6)][BF(4)](2) (M = Ru, Os) were obtained between 100 and 300 K in intervals of 50 K. All three salts are isostructural and crystallized in the tetragonal space group I4/m (No. 87). As for the corresponding [M(CO)(6)][SbF(6)](2) salts (M = Fe, Ru, Os), similar unit cell parameters and vibrational fundamentals were also found for the three [BF(4)](-) compounds. For the structurally characterized salts [M(CO)(6)][BF(4)](2) (M = Fe, Os), very similar bond parameters for both cations and anions were found. Hence, the invariance of structural and spectroscopic properties of [M(CO)(6)](2+) cations (M = Fe, Ru, Os) extended from the fluoroantimonates [Sb(2)F(11)](-) and [SbF(6)](-) as counteranions also to [BF(4)](-).

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].

A two step synthesis to the isocyanotris(trifluoromethyl)borate anion, [(CF3)3BNC]-, and its isomerization to the cyanotris(trifluoromethyl)borate anion, [(CF3)3BCN]-, at temperatures above 150 degrees C are presented. In the first step (CF3)3BNCH was obtained by reacting (CF3)3BCO with hydrogen cyanide followed by deprotonation of the HCN adduct with Li[N(SiMe3)2] in toluene. The thermal behavior of K[(CF3)3BNC] and K[(CF3)3BCN] were investigated by differential scanning calorimetry (DSC), and K[BF4] was identified as a major solid decomposition product. The enthalpy of the isocyanide-cyanide rearrangement, deltaH(iso) = -35 +/- 4 kJ mol(-1), was obtained from DSC measurements, and the activation energy, E(a) = 180 +/- 20 kJ mol(-1), from kinetic measurements. The isomerization was modeled as an intramolecular reaction employing DFT calculations at the B3LYP/6-311+G(d) level of theory yielding a reaction enthalpy of deltaH(iso) = -36.1 kJ mol(-1) and an activation energy of E(a) = 155.7 kJ mol(-1). The solid-state structures of K[(CF3)3BNC] and K[(CF3)3BCN] were determined by single-crystal X-ray diffraction. Both salts are isostructural and crystallize in the orthorhombic space group Pnma (no. 62). In the crystals the borate anions possess C(s) symmetry, while for the energetic minimum C3 symmetry is predicted by DFT calculations. The borate anions have been characterized by IR and Raman spectroscopy as well as by NMR spectroscopy. The assignment of the IR and Raman bands is supported by their calculated wavenumbers and intensities. The spectroscopic and structural properties of both borate anions are compared to the properties of the isoelectronic borane carbonyl (CF3)3BCO and the [B(CF3)4]- anion as well as to those of other related species.

A series of tetracyanoborate salts M[B(CN)4] with the singly charged cations of Li+, Na+, Rb+, Cs+, [NH4]+, Tl+, and Cu+ as well as the THF solvate tetracyanoborates Na[B(CN)4] x THF and [NH4][B(CN)4] x THF were synthesized and their X-ray structures, vibrational spectra, solubilities in water, and thermal stabilities determined and compared with already known M[B(CN)4] salts. Crystallographic data for these compounds are as follows: Na[B(CN)4], cubic, Fd3m, a = 11.680(1) A, Z= 8; Li[B(CN)4], cubic, P43m, a = 5.4815(1) A, Z= 1; Cu[B(CN)4], cubic, P43m, a = 5.4314(7) A, Z= 1; Rb[B(CN)4], tetragonal, /4(1)/a, a = 7.1354(2) A, c= 14.8197(6) A, Z= 4; Cs[B(CN)4], tetragonal, /4(1)/a, a = 7.300(2) A, c = 15.340(5) A, Z= 4; [NH4][B(CN)4], tetragonal, /4(1)/a, a = 7.132(1) A, c = 14.745(4) A, Z= 4; Tl[B(CN)4], tetragonal, /4(1)/a, a = 7.0655(2) A, c = 14.6791(4) A, Z= 4; Na[B(CN)4] x THF, orthorhombic, Pnma, a = 13.908(3) A, b = 9.288(1) A, c = 8.738(1) A, Z= 4; [NH4][B(CN)4] x THF, orthorhombic, Pnma, a = 8.831(1) A, b = 9.366(2) A, c = 15.061(3) A, Z= 4. The cubic Li+, Na+, and Cu+ salts crystallize in a structure consisting of two interpenetrating independent tetrahedral networks of M cations and [B(CN)4]- ions. The compounds with the larger countercations (Rb+, Cs+, Tl+, and [NH4]+) crystallize as tetragonal, also with a network arrangement. The sodium and ammonium salts with the cocrystallized THF molecules are both orthorhombic but are not isostructural. In the vibrational spectra the two CN stretching modes A1 and T2 coincide in general and the band positions are a measure for the strength of the interionic interaction. An interesting feature in the Raman spectrum of the copper salt is the first appearance of two CN stretching modes.

First examples for the syntheses of trifluoromethyl transition metal complexes by conversion of a cyano into a trifluoromethyl ligand are described. The fluorination of [(Bu4N)-Bu-n][Au(CN)(4)] with OF in CH2Cl2 leads to the formation of a mixture of gold complexes of the type [AuFxCly(CF3)(4-x-y)](-) (x = 0-4, y = 0-2). Ligand exchange reactions of [AuFxCly(CF3)(4-x-y)](-) (x = 0-4, y = 0-2) with (CH3)(3)SiY (Y = Cl, CN) are performed resulting in anions of the type [AuYx(CF3)(4-x)](-) (X = 0-4). All products are characterised by C-13- and F-19 NMR spectroscopy. (C) 2004 Elsevier B.V. All rights reserved.

Short-lived (CF(3))(3)B and (CF(3))(3)BCF(2) are generated as intermediates by thermal dissociation of (CF(3))(3)BCO and F(-) abstraction from the weak coordinating anion [B(CF(3))(4)](-), respectively. Both Lewis acids cannot be detected because of their instability with respect to rearrangement reactions at the B-C-F moiety. A cascade of 1,2-fluorine shifts to boron followed by perfluoroalkyl group migrations and also difluorocarbene transfer reactions occur. In the gas phase, (CF(3))(3)B rearranges to a mixture of linear perfluoroalkyldifluoroboranes C(n)()F(2)(n)()(+1)BF(2) (n = 2-7), while the respective reactions of (CF(3))(3)BCF(2) result in a mixture of linear (n = 2-4) and branched monoperfluoroalkyldifluoroboranes, e.g., (C(2)F(5))(CF(3))FCBF(2). For comparison, the reactions of [CF(3)BF(3)](-) and [C(2)F(5)BF(3)](-) with AsF(5) are studied, and the products in the case of [CF(3)BF(3)](-) are BF(3) and C(2)F(5)BF(2) whereas in the case of [C(2)F(5)BF(3)](-), C(2)F(5)BF(2) is the sole product. In contrast to reports in the literature, it is found that CF(3)BF(2) is too unstable at room temperature to be detected. The decomposition of (CF(3))(3)BCO in anhydrous HF leads to a mixture of the new conjugate Brønsted-Lewis acids [H(2)F][(CF(3))(3)BF] and [H(2)F][C(2)F(5)BF(3)]. All reactions are modeled by density functional calculations. The energy barriers of the transition states are low in agreement with the experimental results that (CF(3))(3)B and (CF(3))(3)BCF(2) are short-lived intermediates. Since CF(2) complexes are key intermediates in the rearrangement reactions of (CF(3))(3)B and (CF(3))(3)BCF(2), CF(2) affinities of some perfluoroalkylfluoroboranes are presented. CF(2) affinities are compared to CO and F(-) affinities of selected boranes showing a trend in Lewis acidity, and its influence on the stability of the complexes is discussed. Fluoride ion affinities are calculated for a variety of different fluoroboranes, including perfluorocarboranes, and compared to those of the title compounds.

The first syntheses of trifluoromethyl-complexes of platinum through fluorination of cyanoplatinates are reported. The fluorination of tetracyanoplatinates(II), K-2[Pt(CN)(4)], and hexacyanoplatinates(IV), K-2[Pt(CN)(6)], with CIF in anhydrous HF leads after working up of the products to K-2[(CF3)(2)F2Pt(mu-OH)(2)PtF2(CF3)(2)].2H(2)O. The structure of the salt is determined by a X-ray structure analysis, P2(1)/c (Nr. 14), a = 11.391(2), b = 11.565(2), c = 13.391(3) Angstrom, beta = 90.32(3)degrees, Z = 4, R-1 = 0.0326 (I > 2sigma(I)). The reaction of [Bu4N](2)[Pt(CN)(4)] with CIF in CH2Cl2 generates mainly cis-[Bu4N](2)[PtCl2(CF3)(4)] and fac-[Bu4N](2)[PtCl3(CF3)(3)], but in contrast that of [Bu4N](2)[Pt(CN)(6)] with CIF in CH2Cl2 results cis-[Bu4N](2)[PtX2(CF3)(4)], [Bu4N](2)[PtX(CF3)(5)] (X = F, Cl) and [Bu4N](2)[Pt(CF3)(6)]. In the products [Bu4N](2)[PtXn(CF3)(6-n)] (X = F, Cl, n = 0-3) it is possibel to exchange the fluoroligands into chloro- and cyano-ligands by treatment with (CH3)(3)SiCl and (CH3)(3)SiCN at 50 degreesC. With continuing warming the trifluoromethyl-ligands are exchanged by chloro- and cyanoligands, while as intermediates CF2Cl and CF2CN ligands are formed. The identity of the new trifluoromethyl-platinates is proved by Pt-195- and F-19-NMR-spectroscopy.

Make mine a triple: The tetraphenyl phosphonium salts of [(CF3)3BCX]− (X=P, As) are stable even well above room temperature. The synthesis of these first phospha- and arsaethynyl complexes of boron from (CF3)3BCO is carried out in two steps (see scheme). The complex [(CF3)3BCAs]− is the first stable anionic arsaalkyne. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z54034_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

AbstractÜber erste Synthesen von Trifluormetylkomplexen des Platins durch Fluorierung von Cyanoplatinaten wird berichtet. Die Fluorierung des Tetracyanoplatinates(II), K2[Pt(CN)4], und Hexacyanoplatinates(IV), K2[Pt(CN)6], mit ClF in wasserfreier HF führt nach Aufarbeitung der Produkte zu K2[(CF3)2F2Pt(μ‐OH)2PtF2(CF3)2]·2H2O. Der Aufbau des Salzes ist durch eine Röntgenstrukturanalyse abgesichert, P21/c (Nr. 14), a = 11.391(2), b = 11.565(2), c = 13.391(3)Å, β = 90.32(3)°, Z = 4, R1 = 0.0326 (I > 2σ(I)). Bei der Reaktion von [Bu4N]2[Pt(CN)4] mit ClF in CH2Cl2 entstehen hauptsächlich cis‐[Bu4N]2[PtCl2(CF3)4] und fac‐[Bu4N]2[PtCl3(CF3)3], dagegen führt die Umsetzung von [Bu4N]2[Pt(CN)6] mit ClF in CH2Cl2 zu cis‐[Bu4N]2[PtX2(CF3)4], [Bu4N]2[PtX(CF3)5] (X = F, Cl) und [Bu4N]2[Pt(CF3)6]. In den Produkten [Bu4N]2[PtXn(CF3)6‐n] (X = F, Cl, n = 0—3) lassen sich mit (CH3)3SiCl und (CH3)3SiCN bei 50 °C die Fluoroliganden gegen Chloro‐ bzw. Cyanoliganden austauschen. Bei weiterem Erwärmen werden außerdem die Trifluormethylliganden stufenweise gegen Chloro‐ bzw. Cyanoliganden ersetzt, wobei sich intermediär CF2Cl‐ bzw. CF2CN‐Liganden bilden. Der Aufbau der neuen Trifluormethylplatinate wird durch die Analyse der 195Pt‐ und 19F‐NMR‐Spektren eindeutig belegt.

Structures, relative energies, vibrational spectra, and ESR parameters of the 17e(-) molecule V(CO)(6) in O-h, D-3d, D-4h, and D-2h symmetry have been computed with density functional and high-level ab initio methods. At all theoretical levels applied, the same energetic order is obtained, D-3d < D-2h < D-4h < O-h, with the D-2h structure as a transition state connecting equivalent D-3d species. At the RCCSD(T)/AE2 level using UBP86/AE2 geometries, the energies of the D-2h, D-4h and O-h species relative to that of D-3d minimum are predicted to be 210, 535, and 731 cm(-1), respectively. According to molecular dynamics simulations on the UBP86/AE1 potential energy surface, the D3d minimum is preserved at very low temperatures (around 16 K), whereas at 300 K the molecule is highly fluxional with an averaged structure indistinguishable from that of [V(CO)6](-) with its O-h symmetric ground state. Nearly complete IR and Raman spectra Of V(CO)(6) and V((CO)-C-13)(6) have been recorded at 300 K for the first time in the gas phase, in solution, and at cryogenic temperatures in Ne and Ar matrices. The spectra show a pronounced temperature dependence, especially for the Jahn-Teller active modes, E-g and T-2g. The observed infrared matrix spectra generally agree well with the calculated spectrum (BP86/AE2 level) for the D-3d structure and much less with that of the D-4h isomer. The A(1g) modes in the Raman spectra are reasonably well reproduced computationally in the harmonic approximation, whereas this approximation breaks down for the E-g and T-2g bands, as expected. Further evidence for the D-3d symmetry Of V(CO)(6) is obtained from a reanalysis of the experimental ESR spectrum that is reported in the literature. The observed ordering of the hyperfine coupling constants A(\\) and A(perpendicular to) is reproduced theoretically only when distortion to D-3d symmetry is assumed. In addition, the bonding properties Of V(CO)(6) are compared to those Of [V(CO)6](-) and Cr(CO)(6).

Nucleophilic addition of fluoride ions at the carbonyl carbon atom in (CF3)3BCO in liquid sulfur dioxide leads to the formation of the boron acyl fluoride ion [(CF3)3BC(O)F]− (see structural formula), the first example of a compound with a BC(O)F group and an anionic acyl fluoride. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z50303_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Metathetical processes were used to convert N5SbF6 into N5[B(CF3)4] and (N5)2SnF6. The latter salt is especially noteworthy because it contains two N5+ ions per anion, thus demonstrating that salts with touching polynitrogen cations can be prepared. This constitutes an important milestone towards our ultimate goal of synthesizing a stable, ionic nitrogen allotrope. The stepwise decomposition of (N5)2SnF6 yielded N5SnF5. Multinuclear NMR spectra show that in HF the SnF5- ion exists as a mixture of Sn2F(10)(2-) and Sn4F(20)(4-) ions. Attempts to isolate FN5 from the thermolysis of (N5)2SnF6 were unsuccessful, yielding only the expected decomposition products, FN3, N2, trans-N2F2, NF3, and N2.

AbstractEs wird eine neue effiziente Synthese für Tetracyanoborate im molaren Maßstab ausgehend von den leicht zugänglichen Reagenzien K[BF4], LiCl und KCN beschrieben. Das nach dem Sinter‐Prozess und Aufarbeitung erhaltene Tetracyanoborat ist im Gegensatz zu den Produkten der bisher bekannten Reaktionen ein weißer Feststoff, der frei von Verunreinigungen ist. Das thermische Verhalten der gemischten Cyanofluoroborate, K[BFx(CN)4—x] (x = 1—3), wurde näher untersucht, um den Mechanismus des Ligandenaustausches bei der K[B(CN)4]‐Synthese aufzuklären. Weiterhin werden einige Metathese‐Reaktionen für die Herstellung unterschiedlicher Tetracyanoborate beschrieben.