Exhaustive chlorination of [B12H12]2- without chlorine gas and the use of [B12Cl12]2- as a Supporting anion in catalytic hydrodefluorination of aliphatic C-F bonds

The fully chlorinated closo-dodecaborate salt Cs(2)[B(12)Cl(12)] was prepared in high yield from Cs(2)[B(12)H(12)] and SO(2)Cl(2) in acetonitrile at refluxing temperature. [Ph(3)C](2)[B(12)Cl(12)] was obtained by simple metathesis reactions. Catalytic hydrodefluorination of benzotrifluoride sp(3) C-F bonds was accomplished using [Ph(3)C](2)[B(12)Cl(12)] as a precatalyst and Et(3)SiH as a stoichiometric reagent. Full consumption of the sp(3) C-F bonds in p-FC(6)H(4)CF(3) and C(6)F(5)CF(3) with a turnover number up to 2000 was achieved.     

Polychloride monoanions from [Cl3]- to [Cl9]- : a Raman spectroscopic and quantum chemical investigation

Polychloride monoanions stabilized by quaternary ammonium salts are investigated using Raman spectroscopy and state-of-the-art quantum-chemical calculations. A regular V-shaped pentachloride is characterized for the [N(Me)(4)][Cl(5)] salt, whereas a hockey-stick-like structure is tentatively assigned for [N(Et)(4)][Cl(2)???Cl(3)(-)]. Increasing the size of the cation to the quaternary ammonium salts [NPr(4)](+) and [NBu(4)](+) leads to the formation of the [Cl(3)](-) anion. The latter is found to be a pale yellow liquid at about 40 °C, whereas all the other compounds exist as powders. Further to these observations, the novel [Cl(9)](-) anion is characterized by low-temperature Raman spectroscopy in conjunction with quantum-chemical calculations.     

Superelectrophilic Behavior of an Anion Demonstrated by the Spontaneous Binding of Noble Gases to [B12Cl11]−

It is common and chemically intuitive to assign cations electrophilic and anions nucleophilic reactivity, respectively. Herein, we demonstrate a striking violation of this concept: The anion [B₁₂Cl₁₁]⁻ spontaneously binds to the noble gases (Ngs) xenon and krypton at room temperature in a reaction that is typical of “superelectrophilic” dications. [B₁₂Cl₁₁Ng]⁻ adducts, with Ng binding energies of 80 to 100 kJ mol⁻¹, contain B−Ng bonds with a substantial degree of covalent interaction. The electrophilic nature of the [B₁₂Cl₁₁]⁻ anion is confirmed spectroscopically by the observation of a blue shift of the CO stretching mode in the IR spectrum of [B₁₂Cl₁₁CO]⁻ and theoretically by investigation of its electronic structure. The orientation of the electric field at the reactive site of [B₁₂Cl₁₁]⁻ results in an energy barrier for the approach of polar molecules and facilitates the formation of Ng adducts that are not detected with reactive cations such as [C₆H₅]⁺. This introduces the new chemical concept of “dipole-discriminating electrophilic anions.”     

Drei Wege zur Oxydation von [Ta6Cl12]2+ ([Ta6Br12]2+ und [Nb6Cl12]2+)

Three Oxidation Paths of [Ta₆Cl₁₂]²⁺ ([Ta₆Br₁₂]²⁺ and [Nb₆Cl₁₂]²⁺) [Ta₆Cl₁₂]²⁺ is oxidized autocatalytically to [Ta₆Cl₁₂]⁴⁺ by HNO₃. The titration of [Ta₆Cl₁₂]²⁺ with KBrO₃ (in HBr-containing solutions) or with Ce⁴⁺ or K₂Cr₂O₇ (in HNO₃-containing solutions) leads to a clear [Ta₆Cl₁₂]³⁺ step. The further titration leads beside [Ta₆Cl₁₂]⁴⁺ to the formation of Ta₂O₅(· xH₂O). [Ta₆Cl₁₂]²⁺ behaves with KBrO₃(+ HBr) equally, but the formation of [Ta₂O₅](· xH₂O) is only small. [Nb₆Cl₁₂]²⁺ (22°C) titrated with Ce(ClO₄)₄ in 2n HClO₄ gives the first potential step nearby exact ([Nb₆Cl₁₂]³⁺) and at a very slow titration in a second step a precipitation of Nb₂O₅(· xH₂O) occurs, which adsorbed Ce⁴⁺ additionally. At ?15°C with Ce(ClO₄)₄ the first potential step was exactly at [Nb₆Cl₁₂]^2+→3+, while the second step needs a distinct additional consumption of titer. (Formation of [Nb₆Cl₁₂]⁴⁺ and beside it [Nb₂O₅](· xH₂O)). From the titration curves and sections of its normal progress in all cases we get the normal potentials 2+/3+ and 3+/4+ with an accuracy of ± 0.01 volt. In alkaline solution the complexes are oxidized with air-oxygen to [M₆X₁₂](OH)₆^2?, while the Br-containing complexes suffer hydrolysis afterwards.     

Investigation of Large Polychloride Anions: [Cl11]−, [Cl12]2−, and [Cl13]−

For decades the chemistry of polyhalides was dominated by polyiodides and more recently also by an increasing number of polybromides. However, apart from a few structures containing trichloride anions and a single report on an octachloride dianion, [Cl₈]^2?, polychlorine compounds such as polychloride anions are unknown. Herein, we report on the synthesis and investigation of large polychloride monoanions such as [Cl₁₁]^? found in [AsPh₄][Cl₁₁], [PPh₄][Cl₁₁], and [PNP][Cl₁₁]?Cl₂, and [Cl₁₃]^? obtained in [PNP][Cl₁₃]. The polychloride dianion [Cl₁₂]^2? has been obtained in [NMe₃Ph]₂[Cl₁₂]. The novel compounds have been thoroughly characterized by NMR spectroscopy, single‐crystal Raman spectroscopy, and single‐crystal X‐ray diffraction. The assignment of their spectra is supported by molecular and periodic solid‐state quantum‐chemical calculations.     

Die Kristallstrukturen der Dicaesium-Dodekahalogeno-closo-Dodekaborate Cs2[B12X12] (X = Cl,Br, I) und ihrer Hydrate

The Crystal Structures of the Dicesium Dodecahalogeno-closo-Dodecaborates Cs₂[B₁₂X₁₂] (X = Cl, Br, I) and their Hydrates The perhalogenated derivatives Cs₂[B₁₂X₁₂] (X = Cl - I) have been synthesized by reaction of Cs₂[B₁₂H₁₂] with the respective elemental halogens (Cl₂, Br₂ and I₂). Upon recrystallization from aqueous solution colourless, face-rich single crystals of the dihydrates (Cs₂[B₁₂X₁₂] · 2 H₂O) are obtained first which can be dehydrated topotactically via the monohydrates (Cs₂[B₁₂X₁₂] · H₂O) leaving to the solvent-free compounds (Cs₂[B₁₂X₁₂]) behind without loss of their crystallinity. The ionic cesium salts were characterized by single crystal X-ray diffraction. All three halogenoborates are isostructural and they crystallize at room temperature in the trigonal space group (Cs₂[B₁₂Cl₁₂]: a = 959.67(3) pm, c = 4564.2(2) pm; Cs₂[B₁₂Br₁₂]: a = 997.92(3) pm, c = 4766.4(3) pm; Cs₂[B₁₂I₁₂]: a = 1047.05(4) pm, c = 5018.3(3) pm; Z = 6). The crystal structures consist of a cubic closest packed host lattice formed by two crystallographically inequivalent quasi-icosahedral [B₁₂X₁₂]^2- anions (Cs₂[B₁₂Cl₁₂]: d(B-B) = 178 - 179 pm, d(B-Cl) = 179 - 180 pm; Cs₂[B₁₂Br₁₂]: d(B-B) = 176 - 180 pm, d(B-Br) = 195 - 197 pm; Cs₂[B₁₂I₁₂]: d(B-B) = 177 - 182 pm, d(B-I) = 214 - 217 pm). By ordered occupation of half of the tetrahedral and formally all octahedral interstices in every intermediate layer with Cs⁺ cations, a structure emerges where (Cs1)⁺ is trigonally non-planar coordinated by three (CN = 9) and (Cs2)⁺ tetrahedrally coordinated by four (CN = 12) [B₁₂X₁₂]^2- anions. Thereby triangular faces of halogen atoms of the icosahedral clusters are coordinatively effective in both cases. In their mono- and dihydrates the incomplete coordination sphere of (Cs1)⁺ is completed by one and two water molecules, respectively. The thermal decomposition of the dicesium dodecahalogeno-closo-dodecaborate hydrates and their dehydration products was investigated using DTA/TG methods in a temperature range between room temperature and 1200 °C. Additionally the compounds were also characterized by ¹¹B-NMR spectroscopy in aqueous solution.     

[Li(12-Krone-4)]Cl: Kristallstruktur und IR-Spektrum

[Li(12-Crown-4)]Cl: Crystal Structure and I.R. Spectrum Colourless single crystals of [Li(12-crown-4)]Cl were obtained from acetonitrile solutions of LiCl in the presence of 12-crown-4. They were characterized by i. r. spectroscopy as well as by an X-ray structure determination. Space group P4/n, Z = 2, 1 080 observed unique reflections, R = 0.034. Lattice dimensions at ?50°C; a = 837.8(5), c = 752.0(2) pm. [Li(12-crown-4)]Cl forms ion pairs with tetragonal symmetry and bond lengths Li? O of 212.8 pm and Li? Cl of 229.0 pm.     

Synthesen,Eigenschaften und Kristallstrukturen der Cluster‐Salze Bi6[PtBi6Cl12] und Bi2/3[PtBi6Cl12]

Syntheses, Properties and Crystal Structures of the Cluster Salts Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂] Melting reactions of Bi with Pt and BiCl₃ yield shiny black, air insensitive crystals of the subchlorides Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂]. Despite the substantial difference in the bismuth content the two compounds have almost the same pseudo‐cubic unit cell and follow the structural principle of a CsCl type cluster salt. Bi₆[PtBi₆Cl₁₂] consists of cuboctahedral [PtBi₆Cl₁₂]^2? clusters and Bi₆²⁺ polycations (a = 9.052(2) Å, α = 89.88(2)°, space group P 1, multiple twins). In the electron precise cluster anion, the Pt atom (18 electron count) centers an octahedron of Bi atoms whose edges are bridged by chlorine atoms. The Bi₆²⁺ cation, a nido cluster with 16 skeletal electrons, has the shape of a distorted octahedron with an opened edge. In Bi_2/3[PtBi₆Cl₁₂] the anion charge is compensated by weakly coordinating Bi³⁺ cations which are distributed statistically over two crystallographic positions (a = 9.048(2) Å, α = 90.44(3)°, space group ). Bi₆[PtBi₆Cl₁₂] is a semiconductor with a band gap of about 0.1 eV. The compound is diamagnetic at room temperature though a small paramagnetic contribution appears towards lower temperature.     

Strukturelle Untersuchungen an Cs2[B12H12]

Structural Investigations on Cs₂[B₁₂H₁₂] The crystal structure of Cs₂[B₁₂H₁₂] has been determined from X‐ray single‐crystal data collected at room temperature. Dicesium dodecahydro‐closo‐dodecaborate crystallizes as colourless, face‐rich crystals (cubic, Fm 3; a = 1128.12(7) pm; Z = 4). Its synthesis is based on the reaction of Na[BH₄] with BF₃(O(C₂H₅)₂) via the decomposition of Na[B₃H₈] in boiling diglyme, followed by subsequent separations, precipitations (with aqueous CsOH solution) and recrystallizations. The crystal structure is best described as anti‐CaF₂‐type arrangement with the Cs⁺ cations in all tetrahedral interstices of the cubic closest‐packed host lattice of the icosahedral [B₁₂H₁₂]^2–‐cluster dianions. The intramolecular bond lengths are in the range usually found in closo‐hydroborates: 178 pm for the B–B and 112 pm for the B–H distance. Twelve hydrogen atoms belonging to four [B₁₂H₁₂]^2– icosahedra provide an almost perfect cuboctahedral coordination sphere to the Cs⁺ cations, and their distance of 313 pm (12 ×) attests for the salt‐like character of Cs₂[B₁₂H₁₂] according to {(Cs⁺)₂([B₁₂H₁₂]^2–)}. The ¹¹B{¹H}‐NMR data in aqueous (D₂O) solution are δ = –12,70 ppm (¹J_B–H = 125 Hz), and δ = –15,7 ppm (linewidth: δν_1/2 = 295 Hz) for the solid state ¹¹B‐MAS‐NMR.     

Diphenyldichlorophosphonium trichloride-chlorine solvate 1:1, [PPh2Cl2]+Cl(3)(-).Cl2: an ionic form of diphenyltrichlorophosphorane. Crystal structures of [PPh2Cl2]+Cl(3)(-).Cl2 and [(PPh2Cl2)+]2[InCl5](2-)

An ionic form of diphenyltrichlorophosphorane, namely, diphenyldichlorophosphonium trichloride isolated as a dichlorine solvate (1), was obtained by treating PPh(2)Cl(3) with excess chlorine. The identity of this species was established by single-crystal X-ray analysis and (31)P, (1)H, and (35)Cl NMR and Raman spectra. Bis(diphenyldichlorophosphonium) pentachloroindate (2) was obtained by the reaction of diphenyltrichlorophosphorane with indium trichloride in dichloromethane for comparison purposes. Its identity was determined by (31)P NMR spectra and single-crystal X-ray analysis.     

Zwei Chloridsilicate des Yttriums: Y3Cl[SiO4]2 und Y6Cl10[Si4O12]

Two Chloride Silicates of Yttrium: Y₃Cl[SiO₄]₂ and Y₆Cl₁₀[Si₄O₁₂] The chloride‐poor yttrium(III) chloride silicate Y₃Cl[SiO₄]₂ crystallizes orthorhombically (a = 685.84(4), b = 1775.23(14), c = 618.65(4) pm; Z = 4) in space group Pnma. Single crystals are obtained by the reaction of Y₂O₃, YCl₃ and SiO₂ in the stoichiometric ratio 4 : 1 : 6 with ten times the molar amount of YCl₃ as flux in evacuated silica tubes (7 d, 1000 °C) as colorless, strongly light‐reflecting platelets, insensitive to air and water. The crystal structure contains isolated orthosilicate units [SiO₄]^4– and comprises cationic layers {(Y2)Cl}²⁺ which are alternatingly piled parallel (010) with anionic double layers {(Y1)₂[SiO₄]₂}^2–. Both crystallographic different Y³⁺ cations exhibit coordination numbers of eight. Y1 is surrounded by one Cl^– and 7 O^2– anions as a distorted trigonal dodecahedron, whereas the coordination polyhedra around Y2 show the shape of bicapped trigonal prisms consisting of 2 Cl^– and 6 O^2– anions. The chloride‐rich chloride silicate Y₆Cl₁₀[Si₄O₁₂] crystallizes monoclinically (a = 1061,46(8), b = 1030,91(6), c = 1156,15(9) pm, β = 103,279(8)°; Z = 2) in space group C2/m. By the reaction of Y₂O₃, YCl₃ and SiO₂ in 2 : 5 : 6‐molar ratio with the double amount of YCl₃ as flux in evacuated silica tubes (7 d, 850 °C), colorless, air‐ and water‐resistant, brittle single crystals emerge as pseudo‐octagonal columns. Here also a layered structure parallel (001) with distinguished cationic double‐layers {(Y2)₅Cl₉}⁶⁺ and anionic layers {(Y1)Cl[Si₄O₁₂]}^6– is present. The latter ones contain discrete cyclo‐tetrasilicate units [Si₄O₁₂]^8– of four cyclically corner‐linked [SiO₄] tetrahedra in all‐ecliptical arrangement. The coordination sphere around (Y1)³⁺ (CN = 8) has the shape of a slightly distorted hexagonal bipyramid comprising 2 Cl^– and 6 O^2– anions. The 5 Cl^– and 2 O^2– anions building the coordination polyhedra around (Y2)³⁺ (CN = 7) form a strongly distorted pentagonal bipyramid.     

Crown compounds for anions: sandwich and half-sandwich complexes of cyclic trimetric perfluoro-o-phenylenemercury with polyhedral closo-[B10H10]2- and closo-[B12H12]2- anions

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively.     

Simple preparations of Pd6Cl12, Pt6Cl12, and Qn[Pt2Cl8+n], n=1, 2 (Q=TBA+, PPN+) and structural characterization of [TBA][Pt2Cl9] and [PPN]2[Pt2Cl10].C7H8

The hexanuclear Pd6Cl12, i.e., the crystal phase classified as beta-PdCl2, was obtained by reacting [TBA]2[Pd2Cl6] with AlCl3 (or FeCl3) in CH2Cl2. The action of AlCl3 on PtCl42-, followed by digestion of the resulting solid in 1,2-C2H4Cl2 (DCE), CHCl3, or benzene, produced Pt6Cl12.DCE, Pt6Cl12.CHCl3, or Pt6Cl12.C6H6, respectively. Treating [TBA]2[PtCl6] with a slight excess of AlCl3 afforded [TBA][Pt2Cl9], whose anion was established crystallographically to be constituted by two "PtCl6" octahedra sharing a face. Dehydration of H2PtCl6.nH2O with SOCl2 gave an amorphous compound closely analyzing as PtCl4, reactive with [Q]Cl in SOCl2 to yield [Q][Pt2Cl9] or [Q]2[Pt2Cl10], depending on the [Q]Cl/Pt molar ratio (Q=TBA+, PPN+). A single-crystal X-ray diffraction study has shown [PPN]2[Pt2Cl10].C7H8 to contain dinuclear anions formed by two edge-sharing PtCl6 octahedra.     

The Crystal Structure of Solvent‐Free Silver Dodecachloro‐closo‐dodecaborate Ag2[B12Cl12] from Aqueous Solution

Colourless octahedral single crystals of solvent‐free Ag₂[B₁₂Cl₁₂] (cubic, Pa3¯; a = 1238.32(7) pm, Z = 4) are obtained by the metathesis reaction of Cs₂[B₁₂Cl₁₂] with an aqueous solution of silver nitrate (AgNO₃) and recrystallization of the crude product from water. The crystal structure is best described as a distorted anti‐CaF₂‐type arrangement in which the quasi‐icosahedral [B₁₂Cl₁₂]^2— anions (d(B—B) = d(B—Cl) = 177—180 pm) are arranged in a cubic closest‐packed fashion. The tetrahedral interstices are filled with Ag⁺ cations which are strongly displaced from their ideal positions. Thereby each silver atom gets coordinated by six chlorine atoms from the edges of three [B₁₂Cl₁₂]^2— anions providing a distorted octahedral coordination sphere to the Ag⁺ cations (d(Ag—Cl) = 283—285 pm, CN = 6).     

Condensed two- and three-dimensional aromatic systems: a theoretical study on the relative stabilities of isomers of CB19H16+, B20H15Cl, and B20H14Cl2 and comparison to B12H10Cl22-, C6H4Cl2, C10H7Cl, and C10H6Cl2

DFT studies (B3LYP/6-31G) on mono- and dichloro derivatives of benzene, naphthalene, B12H12(2-), four-atom-sharing condensed systems B20H16, and monocarborane isomers of B20H16 are used to compare the variation of relative stability and aromaticity between condensed aromatics. The trends in the variation of the relative energies and aromaticity in these two- and three-dimensional systems are similar. Aromaticity, estimated by NICS values, does not change considerably with condensation or substitution. The minor variation in the relative energies of the isomers of chloro derivatives is explained by the topological charge stabilization rule of Gimarc. The compatibility of the cap and ring orbitals decides the relative stability of CB19H16+.