Synthesis and structures of trifluoromethyl-, fluoro-, and azido-substituted hexabenzylhexaazaisowurtzitanes and isolation of a novel hexaazaisowurtzitane-based polycycle

The first hexabenzylhexaazaisowurtzitane cage compounds with trifluoromethyl and azide groups, as well as those with fluorine atoms in the 3- and 4-positions, have been prepared and fully characterized. A study of the substituent influence on the benzene ring regarding the formation of the hexaazaisowurtzitane polycycle in either the 2- or 4-position with CF(3), F, and N(3) revealed an interesting difference. In all cases with CF(3), F, and N(3) substituents in the 4-position, the corresponding hexabenzylhexaazaisowurtzitanes were isolated. The corresponding hexabenzylhexaazaisowurtzitanes were also formed when these substituents were in the 2-position; however, in addition with azide in 2-position a novel type of polycycle was isolated and identified. (15)N NMR data and crystal structures of hexabenzylhexaazaisowurtzitane derivatives were obtained and are discussed in detail.     

Preparation, crystal structures and rapid hydration of P2- and P3-type sodium chromium antimony oxides

Two new Na_x[Cr_(1+x)/2Sb_(1−x)/2]O₂ compounds have been prepared by solid-state reactions in argon. Their structures have been determined by the X-ray Rietveld method. Both new phases together with NaCrO₂-based solid solution comprise brucite-like layers of edge-shared (Cr,Sb)O₆ octahedra but differ by packing mode of the layers and coordination of the interlayer Na⁺ ions. A P3 phase exists at x≈0.5-0.58. It is rhombohedral (R3?m), a=2.966, c=16.937 Å at x≈0.58, with 29% Na⁺ occupancy of trigonal prisms. A P2 phase exists at x≈0.6-0.7. It is hexagonal (P6₃/mmc), a=2.960, c=11.190 Å at x≈0.7, with 37% and 33% Na⁺ occupancy of two non-equivalent trigonal prisms. Both P2 and P3 phases rapidly absorb moisture in air; packing mode is preserved, the a parameter changes slightly but c increases by 24-25%. Very high sodium ion conductivity is predicted for both P2 and P3 anhydrous phases.     

A Persistent α‐Fluorocarbanion and Its Analogues: Preparation,Characterization, and Computational Study

Fluoro power : In agreement with theoretical studies on α‐fluorocarbanions an X‐ray crystal structure shows the α‐fluorobis(phenylsulfonyl)methide anion adopts a pyramidal configuration (see picture). High‐level calculations and NMR spectroscopy studies demonstrate that electron‐withdrawing substituents play a crucial role in modulating the properties of bis(phenylsulfonyl)methide anions.

     

Preparation and Characterization of Alkenyl Aryl Tetrafluoro‐λ6‐sulfanes

Substituted alkenyl aryl tetrafluoro‐λ⁶‐sulfanes have been prepared by the direct addition of readily accessible chlorotetrafluorosulfanyl arenes to primary alkynes. Substitution of an apical fluorine of the pentafluorosulfanyl group enables modulation of the reactivity of this little explored functional group while at the same time facilitating the direct investigation of aryl substituent effects on the aryl tetrafluorosulfanyl‐substituted products.     

The Bis(pentafluoroethyl)germylene Trimethylphosphane Adduct (C2F5)2Ge⋅PMe3: Characterization,Ligand Properties,and Reactivity

The synthesis of the germylene phosphane adduct (C₂F₅)₂Ge?PMe₃ is described. Starting from (C₂F₅)₃GeH in an excess of PMe₃, heating was applied, whereupon reductive elimination of C₂F₅H occurred. The molecular structure was ascertained by X‐ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)₃{Ge(C₂F₅)₂(PMe₃)}] in the CO region. (C₂F₅)₂Ge?PMe₃ turned out to be a π‐accepting ligand comparable to PMe₃, in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3‐dimethyl‐1,3‐butadiene, and σ‐bond insertion reactions were recorded. Activation of the C?Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C₂F₅)₂Cl₂Ge‐CH₂PMe₃], which was fully characterized by X‐ray diffraction.     

Trip2C6H3SeF: the first isolated selenenyl fluoride

Joining the stable: The first examples of the highly instable selenenyl fluorides RSeF are prepared from the reaction on the tin selenide RSeSnMe(3) with XeF(2). Through the use of extremely large protecting groups (m-terphenyl ligands) which stabilizes the RSeF units against disproportionation, the compounds could be isolated and characterized by NMR spectroscopy and single-crystal structure analysis (see structure).     

The chemical bond in polyphosphides: crystal structures, the electron localization function, and a new view of aromaticity in P4(2-) and P5(-)

The incongruent solvation of M(I)4P6 species (M(I) = K, Rb, Cs) in liquid ammonia leads to a broad variety of polyphosphides such as P7(3-), P11(3-), and the putatively aromatic P4(2-) and P5(-), which we investigated by using NMR spectroscopy and single-crystal X-ray structure analysis. The structures of Cs2P4 x 2 NH3, (K@[18]crown-6)3K3(P7)2 x 10 NH3, Rb3P7 x 7 NH3, and (Rb@[18]crown-6)3P7 x 6 NH3 are discussed and compared. The electron localization function ELF is used in a comparison of the chemical bonding of various phosphorus species. The variances of the basin populations provide a well-established measure for electron delocalization and therefore aromaticity. While comparable variance is calculated for P4(2-) and P5(-) it is observed in the lone pairs rather than in the basin populations of the bonds as in the prototypical aromatic hydrocarbons such as benzene or the cyclopentadienide anion. For this behavior, the term "lone pair aromaticity" is proposed.     

(Z)-1-[2-(Triarylstannyl)vinyl]-1-cycloheptanols: Synthesis, characterization, halodemetallation and crystal structures

The synthesis and characterization by ¹H, ¹³C, ¹¹⁹Sn NMR and ¹¹⁹Sn Mössbauer spectroscopy of (Z)-1-[2-(triphenylstannyl)vinyl]-1-cycloheptanol,

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(1), and (Z)-1-[2-tri-p-tolylstannyl)vinyl-1-cycloheptanol,

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(2), are described, together with their halodemetallation by I₂, Br₂ and ICIl to yield derivatives of the types

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(Ar = phenyl or p-tolyl, N = 1, 2; X = I, Br, Cl, respectively). The solid-state structures of four compounds have been determined by X-ray diffraction analysis. In the crystals of

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(1) and

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(2) the Sn atom has a tetrahedral geometry distorted towards trigonal bipyramid as a consequence of a close intramolecular contact with the hydroxyl O(1) atom of 2.742(3) Å and 2.768(3) Å, respectively. A trigonal bipyramidal geometry is found in

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(12) and

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(4), in which significant Sn---O(1) interactions are noted [2.437(8) Å and 2.407(8) Å, respectively].     

Ba2[Ni3N2]: a low-valent nitridonickelate-synthesis, crystal structure, and physical properties

The ternary alkaline-earth nitridonickelate Ba2[Ni3N2] (Ba2[NiI2Ni0N2]) was prepared by the reaction of mixtures of Ba2N and Ni in nitrogen gas of ambient back-pressure at 1173 K. The crystal structure determined by X-ray single-crystal and powder diffraction methods as well as from neutron diffraction data at various temperatures between 2 and 298 K is orthorhombic (Cmca (no. 64), 298 K: a=715.27(18) pm, b=1032.99(21) pm, c=740.12(20) pm) and provides the first example of a nitridonickelate with a two-dimensional complex anion. The Ni2 atom is described with a split position and the corresponding superstructure variants are investigated by theoretical full-potential nonorthogonal local-orbital calculations (FPLO). The average oxidation state of Ni in Ba2[Ni3N2] is +0.67, the lowest average value observed in nitridonickelates so far. Investigations of the physical properties demonstrate that Ba2[Ni3N2] acts as a "poor" metal with a large resistivity of approximately 2.7 mOmega cm at 300 K and exhibits low-dimensional magnetism with antiferromagnetic ordering at T approximately 90 K. XAS spectra correspond with low-valent Ni states.     

Syntheses, crystal and solution structures, ligand-exchange, and ligand-coupling reactions of mixed pentaarylantimony compounds

All possible combinations of mixed pentaarylantimony compounds bearing p-methylphenyl and p-trifluoromethylphenyl groups were synthesized; ArnTol5-nSb (n=0-5: Ar=p-CF3C6H4, Tol=p-CH3C6H4): Tol5Sb (1), ArTol4Sb (2), Ar2Tol3Sb (3), Ar3Tol2Sb (4), Ar4TolSb (5), and Ar5Sb (6). Compounds 2-5 are the first well-characterized examples of mixed acyclic pentaarylantimony species. The structures of 2-6 were determined by X-ray crystallography to feature trigonal-bipyramidal (TBP) geometry with the more electronegative p-trifluoromethylphenyl substituents selectively occupying the apical positions. Consideration of the chemical shifts of the ipso carbons of the aryl and tolyl groups suggested that the solution structures of 1-6 were also TBP, although their pseudorotation could not be frozen even at -80 degrees C. Ligand-exchange reactions (LERs) took place between 1 and 6 at approximately 60 degrees C in [D6]benzene and all six species 1-6 were found in the equilibrium mixture. The relative stabilities of 1-6 were determined quantitatively by comparison of the observed molar ratios of 1-6 in equilibrium with calculated statistical molar ratios, and Ar2Tol3Sb (3) was found to be the most stable. The ligand-coupling reactions (LCRs) of 2-5 in solution were greatly accelerated by adding Cu(acac)2 or Li+TFPB- (TFPB: [3,5-(CF3)2 C6H3]4 B), whereby the rate becomes comparable to the LER. The use of flash vacuum thermolysis (FVT) allowed the LCR to occur with very little ligand-exchange; the exception ArTol4Sb had very fast ligand-exchange. The selectivities of the LCRs were calculated from the yield of the biaryls synthesized by using FVT. These results were highly consistent with reactions catalyzed in solution, in which bitolyl was not obtained at all. The experimental results suggested that the LCR of pentaarylantimony compounds proceeds in the manner of apical-apical coupling.     

The Protonation of HSO3F: Preparation and Characterization of Fluorodihydroxyoxosulfonium Hexafluoroantimonate [H2SO3F]+[SbF6]−

Sulfurtrioxide reacts with the superacidic solutions XF/SbF₅ (X=H, D) to form the corresponding salts [X₂SO₃F]⁺[SbF₆]^?, which are the protonated forms of fluorosulfuric acid. The salts have been characterized by vibrational spectroscopy and a single‐crystal structure analysis. [H₂SO₃F]⁺[SbF₆]^? crystallizes in the monoclinic space group P2₁/n (no. 14) with four formula units in the unit cell. The crystal structure possesses a distorted tetrahedral O₃SF skeleton of the cations, which are linked with two strong hydrogen bridges to [SbF₆]^? anions and forms a one‐dimensional chain. The crystal structure and the vibrational spectra are compared to the quantum‐chemical‐calculated free [H₂SO₃F]⁺ cation. Additionally, an [H₂SO₃F(HF)₂]⁺ unit was calculated at the RHF/6‐311⁺⁺G(d,p) level to simulate H???F hydrogen bridges found in the solid state.