Synthese und Charakterisierung von Fluorenylgallaten und Fluorenylindaten

Synthesis and Characterization of Fluorenyl Gallates and Fluorenyl Indates GaCl₃ reacts with Fluorenyllithium (LiFl) in the ratio 1:4 in Et₂O to [Li(THF)₄][GaFl₄] ( 1 ). The addition of DME (1,2-dimethoxyethane) to solutions of 1 in THF leads to [Li(DME)₃][GaFl₄] ( 2 ) under replacement of THF molecules by DME molecules in the coordination sphere of the Li⁺ ions. Treatment of InCl with LiFl in Et₂O and recrystallization from THF gives [Li(THF)₄][ClInFl₃] ( 3 ), which is formed by an disproportionation reaction. 3 can also be obtained by the reaction of InCl with FlZnCl/LiCl in Et₂O and recrystallization from THF. 1 and 2 crystallize from THF and THF/DME as [Li(THF)₄][GaFl₄] · THF ( 1 · THF) and [Li(DME)₃][GaFl₄] · THF ( 2 · THF), respectively. Crystalline 3 is isolated from the reaction of InCl and FlZnCl/LiCl, while the reaction mixture of InCl and LiFl gives after recrystallization in THF 3 · 1,5 THF. The gallate ions in 1 and 2 differ mainly in the position of the fluorenyl ligands. The unit cells of 3 and 3 · 1,5 THF contain two crystallographic unique ion pairs of [Li(THF)₄][ClInFl₃].     

Syntheses and X-Ray Crystal Structures of Novel Oxonium Ion-12-Crown-4 Complexes Isolated From Liquid Clathrate Media

Abstract

The reactions of Mo(CO)₆ and W(CO)₆ with HCl_(g) in the presence of 12-crown-4 and H₂O have been investigated in toluene. For both reactions, two products were isolated, depending on the oxidation of the metal center. For molybdenum, the Mo^III species, [H₃O⁺ · 12-crown-4]₃[Mo₂Cl₉ ^3-], 1, was obtained from the liquid clathrate layer in the reaction mixture. Upon air oxidation of the reaction mixture, the Mo^v complex, [H₇O₃ ^? · H₄O₂ ⁺ · (12-crown-4)₂][MoOCl₄(H₂O)^?]₂, 2, rapidly formed. For tungsten, the W^II species, [(H₅O₂ ⁺)₂ · 12-crown-4][W(CO)₄Cl^? ₃]₂, 3, deposited from the liquid clathrate layer which upon oxidation formed the W^v complex, [H₃O⁺· 12-crown-4][WOCl₄(H₂O)^?], 4. These reactions were promoted by UV radiation and formed liquid clathrates almost immediately upon reaction. X-ray crystal structures were performed on each compound. Complexes 1 and 4 have H₃O⁺ oxonium ions involved in complex hydrogen bonded arrays with the 12-crown-4 acceptor molecules. The H₅O₂ ⁺ oxonium ions in 2 and 3 contain extremely short O…O separations, equivalent to the shortest O-H…O bonds known. Also isolated in complex 2 was the H₇O₃ ⁺ oxonium ion which contains an unusual linear O…O…O core.     

A DFT Study on the Selective Extraction of Metallic Ions by 12-Crown-4

In order to predict the extraction ability of 12-crown-4 for different metallic ions, the complexes [M(12-crown-4)] and [M(H₂O)₄] (where M=Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, Ca²⁺, Cu²⁺ and Zn²⁺) were investigated by the density functional theory without restrictions for their geometry. The metal binding capability was evaluated using the binding energy, and the effect of nature of the metal on the binding properties was also studied. The results of the calculations showed that the coordination ability of a donor molecule towards different metal ions increased in proportion to their ionization potential. In addition, based on the extraction distribution coefficient, we found that 12-crown-4 can selectively extract Cu²⁺ and Be²⁺ ions from aqueous solutions of mixed cations. Obviously, the stability of complexes and the extraction power of extractants depend greatly on the nature of the metal ions. Calculation results from our study could be used to predict the extraction power of this crown ether and could play a guiding role in planning experiments.     

Diphenylberyllium Reinvestigated: Structure,Properties, and Reactivity of BePh2, [(12-crown-4)BePh]+, and [BePh3]−

The first synthesis of BePh₂ was accomplished almost a century ago. However, its structure has remained unknown so far, while the corresponding aryls of the elements adjacent to beryllium in the periodic table are well investigated. Herein, we present an improved synthesis for diphenylberyllium and show by X-ray diffraction that it forms a trinuclear complex in the solid state. NMR spectroscopy revealed that this structure is also retained in solution but exhibits dynamic behavior. Its stability against heat and coordinating solvents is discussed and the possible obstacles to the synthesis of BePh₂ from BeCl₂ are examined. In the process of this study two ether adducts, BePh₂⋅Et₂O and Be₂Ph₄⋅Et₂O, have been characterized as well as the previously unknown triphenylberyllate anion. From the latter several single-crystal structures were obtained under various conditions, in which [BePh₃]⁻ is either isolated or acts as a ligand for Li⁺. Furthermore, the crown ether induced selfionization of BePh₂ is described and the resulting [(12-crown-4)BePh]⁺ cation was isolated, which shows an unusual 4+1 coordination around the Be atom.     

Tetramer structure of a lithium thiocyanate complex in triethylamine

The density functional theory B3LYP/6-31+G(d,p) method in the framework of the discrete-continuum model has been applied to study the tetramer structure of a lithium thiocyanate complex in triethylamine (Et₃N) with the use of experimental and calculated manifestations of ion association in the vibrational spectrum of the anion. Analysis of topological characteristics of the electron density distribution at critical point (3,–1) of the [Li⁺NCS^?]₄ and [Li⁺NCS^?]₄Et₃N complexes has been performed.     

Water-rich molybdotellurates: Preparation and crystal structure of Li6[TeMo6O24] · 18 H2O and Li6[TeMo6O24] · Te(OH)6 · 18 H2O

Li₆[TeMo₆O₂₄] · 18 H₂O is triclinic (space group P1 , a = 1 041.7(1), b = 1 058.6(1), c = 1 070.8(1) pm, α = 61.08(1), β = 60.44(1), γ = 73.95(1)°). Single crystal X-ray structure analysis (Z = 1, 295 K, 317 parameters, 3 973 reflections, R_g = 0.0250) revealed an infinite branched chain of edge-sharing Li coordination polyhedra to be the prominent structural feature. One of the four crystallographically independent Li⁺ is coordinated octahedrally. The coordination polyhedra of the remaining Li⁺ are distorted trigonal bipyramids. Only three unique oxygen atoms (O(9), O(10), O(12)) of the centrosymmetric [TeMo₆O₂₄]^6? anion are bound to Li⁺. The further positions in the coordination spheres of the Li⁺ are occupied by water molecules. Intermolecular hydrogen bonds involve mainly oxygen atoms of the [TeMo₆O₂₄]^6? anion as nearly equivalent proton acceptors without regard to their different bonding modes to Te and Mo, respectively. Li₆[TeMo₆O₂₄] · Te(OH)₆ · 18 H₂O crystallizes monoclinically in space group P2₁/n with Z = 4, a = 994.1(3), b = 2 344.8(10), c = 1 764.9(4) pm, and β = 91.36(4)°. Single crystal structure analysis with least squares refinement of 627 parameters (5 900 reflections, 295 K) converged to R_g = 0.0324. There are six unique Li⁺ cations. The coordination polyhedra of Li(1), Li(2), Li(3), and Li(4) are linked by common edges to yield an eight membered centrosymmetric strand. The coordination polyhedra of the remaining two Li⁺ sites (Li(5), Li(6)) are connected to a dimeric unit via a common corner. All oxygen atoms of the Te(OH)₆ molecule are involved in the coordination of Li⁺. However, only three oxygen atoms (O(13), O(18), O(23)) of the [TeMo₆O₂₄]^6? anion which lacks crystallographic symmetry are involved in the coordination of Li⁺. The oxygen atoms of the anion act as proton acceptors in hydrogen bonds of predominantly medium strength. Te(OH)₆ molecules and [TeMo₆O₂₄]^6? anions connected by strong hydrogen bonds form an infinite chain.     

Divide and Stack Up: Boron‐Based Sandwich Cluster as a Subnanoscale Propeller

Typical salts are composed of positive and negative ions that appear alternatively, whereas decorated layered materials normally have ions anchored on the polygonal sites. In this way, the ions are spatially fixed and the system is stabilized on electrostatic grounds. Here we report on a unique boron‐lithium cluster, B₇Li₄^?, which contains a disk‐like B₇ core, being sandwiched by a Li₃ ring and an isolated Li atom. All Li centers are stacked exactly on the B atoms from top or bottom, rather than being anchored on triangular B₃ sites. The cluster shows dynamic fluxionality, whose Li₃ ring rotates freely on the B₇ disk even at below room temperature (200 K), akin to a subnanoscale propeller. The rotation barrier is only 0.37 kcal mol^?1 at the single‐point CCSD(T) level. The sandwich shape facilitates intramolecular charge‐transfers, leading to a [Li₃]⁺[B₇]^3?[Li]⁺ salt complex. The [Li₃]⁺ layer has 2σ aromaticity, while [B₇]^3? core is robust with both π and σ sextets. Three‐fold π/σ aromaticity collectively stabilizes the system, as well as underlies its dynamic fluxionality. The interlayer bonding turns out to be strong, dominated by ionic interactions (of the order of 3–4 eV per Li₃/Li unit). The work demonstrates a propeller at the subnanoscale, which is dynamically fluxional despite strong covalent and ionic bonding.     

Morpholin als ambidenter Ligand

Morpholine as Ambident Ligand The reaction of MeInCl₂ with Li‐morpholinate [Li(Morph)] at 20 °C in THF gave after work‐up and recrystallization from diglyme the salt [Li(Diglyme){In₃Me₂Cl₄(Morph)₄}]·Diglyme ( 1 ). The treatment of the reaction mixture of MesInCl₂/Li(Morph) with wet THF yield as only isolated compound the coordination polymer [Li₆Cl₆(HMorph)₃] ( 2 ). Under similar conditions the reaction of InCl₃ with Li(Morph) led after work‐up in wet THF to [Li(Diglyme)₂][InCl₄(HMorph)₂] ( 3 ). 1 – 3 were characterized by NMR and IR spectroscopy as well as by X‐ray analysis. According to this, 1 contains the trinuclear anion [In₃Me₂Cl₄(Morph)₄]^? in which one of the morpholinate ligands is coordinated via N atom to the In³⁺ ions, while the O atom belongs to the coordination sphere of the Li⁺ ion. In 2 , LiCl forms a hexagonal heteroprismn, in which the morpholine molecules are responsible for a 3d network via coordination of both Lewis‐basic heteroatoms. 3 contains trans‐[InCl₄(Hmorph)₂]^? ions, connected by hydrogen bonding along [011].     

Solvation of electrosprayed ions in the accumulation/collision hexapole of a hybrid Q-FTMS

In an effort to spectroscopically determine the structures of solvated ions composed of nucleic acid bases and amino acids, methods for their gas-phase synthesis have been studied. Ions were electrosprayed and solvated in the accumulation cell of a hybrid Q-FTICR filled with methanol or water vapor at ∼10⁻² bar. There were subsequently transferred to the FTICR cell at 10⁻¹⁰ mbar. Following their isolation in the FTICR, they can be investigated by studying their unimolecular blackbody infrared radiative dissociation (BIRD) or infrared multiple photon dissociation (IRMPD) spectroscopy. The IRMPD spectra for (Ade)₂Li⁺ and (Ade)₂Li(H₂O)⁺ are reported and compared as well as BIRD rate constants for multiply solvated and metalated adenine ions.     

Guanidinium-selective PVC membrane electrodes based on crown ethers

Guanidinium-selective membrane electrodes were constructed with dibenzo-24-crown-8, dibenzo-27-crown-9, tribenzo-27-crown-9 or dibenzo-30-crown-10. The detection limits and selectivity coefficients towards different interfering ions, such as Li⁺, Na⁺, K⁺, NH⁺₄, Mg²⁺ and Ca²⁺ were determined. The electrode with dibenzo-27-crown-9 shows linear response over the range 10^?1–10^?4 M, with selectivity coefficients about 10^?2 for most alkali and alkaline earth metal ions.     

Solvation effect of the cation of the supporting electrolyte in hexamethylphosphoramide

Polarographic reductions of sodium and potassium ions in hexamethylphosphoramide (HMPA) have been examined in various supporting electrolytes. The supporting electrolytes, which have much the same solvated radii and much the same electrocapillary curves, sometimes have a significantly different influence on the polarographic reductions of metal ions. The Li⁺ and Hex₄N⁺ ions provide a typical example. Their effective radii are seen to have much the same characteristics. However, the polarographic reduction of the sodium ion shows a difference in shape between that occurring in Li⁺ solution and that in Hex₄N⁺ solution. Another example is found in the case of Et₄N⁺, Me₄N⁺ and 5N6⁺, whose r_eff and the electrocapillary curves are much the same. However, the polarographic reductions of the sodium and potassium ions are different in these solutions. The solvation number of the solvent molecule of the supporting electrolyte cation seems to exert a great influence on these reductions. The electrocapillary curves were also examined with the tetradodecylammonium ion, tetradecylammonium ion and tetraphenylphosphonium ion used as the supporting electrolytes. The inhibition of the reduction of metal ion for these cations is evidence for their lack of solvation. The effects of the solvated asymmetrical tetraalkylammonium ions on the polarographic behaviour were also examined. When some methyl groups cooperate with the tetraalkylammonium ion, the chemical character is between that of the Et₄N⁺ ion and that of the Me₄N⁺ ion.     

Die Kristallstrukturen von {Li3(12-Krone-4)2[HC(CN)2]3}, {Na(15-Krone-5)-[HC(CN)2]} und {Na[N(nBu)4][HC(CN)2]2 · THF}

The Crystal Structures of {Li₃(12-crown-4)₂[HC(CN)₂]₃}, {Na(15-crown-5)[HC(CN)₂]}, and {NaN(nBu)₄[HC(CN)₂]₂ · THF} The preparation and the crystal structures of the title compounds 1 — 3 are described. 1 forms a polymeric chain structure, in which one of the lithium ions is linked by Li…NCC(H)CN… bridges. The remaining lithium ions form (12-crown-4)Li[NCC(H)CN] units, which are coordinated by one of the nitrogen atoms of the dicyanomethanide ions with the lithium ions of the chain. 2 forms an ion pair, in which the sodium ion is coordinated by the five oxygen atoms of the crown ether molecule and by one nitrogen atom of the dicyanomethanide ion. 3 has a threedimensional network, in which the sodium ions are coordinated in a distorted tetrahedral manner by the nitrogen atoms of the dicyanomethanide ions. In the cavities of the network the tetrabutylammonium ions and the THF molecules are found.     

A comparison of the unimolecular decomposition pathways of some C7 and C8 ions in the gas phase

[CnH_2n?3]⁺ and [C_nH_2n?4]⁺·(n = 7, 8) ions have been generated in the mass spectrometer from C_nH_2n?3 Br (n = 7, 8) precursors and from two steroids. The relative abundances of competing ‘metastable transitionss’ indicate (partial) isomerization to a common structure (or mixture of structures) prior to decomposition in most examples of all four types of ions. In contrast, [C₈H₁₀O]⁺· and [C₈H₁₂O]⁺· ions, generated from different sources as molecular ions and by fragmentation of steroids, do not decompose through common-intermediates.     

Quantum and Classical Molecular Dynamics of Ionic Liquid Electrolytes for Na/Li‐based Batteries: Molecular Origins of the Conductivity Behavior

Compositional effects on the charge‐transport properties of electrolytes for batteries based on room‐temperature ionic liquids (RTILs) are well‐known. However, further understanding is required about the molecular origins of these effects, in particular regarding the replacement of Li by Na. In this work, we investigate the use of RTILs in batteries, by means of both classical molecular dynamics (MD), which provides information about structure and molecular transport, and ab initio molecular dynamics (AIMD), which provides information about structure. The focus has been placed on the effect of adding either Na⁺ or Li⁺ to 1‐methyl‐1‐butyl‐pyrrolidinium [C₄PYR]⁺ bis(trifluoromethanesulfonyl)imide [Tf₂N]^?. Radial distribution functions show excellent agreement between MD and AIMD, which ensures the validity of the force fields used in the MD. This is corroborated by the MD results for the density, the diffusion coefficients, and the total conductivity of the electrolytes, which reproduce remarkably well the experimental observations for all studied Na/Li concentrations. By extracting partial conductivities, it is demonstrated that the main contribution to the conductivity is that of [C₄PYR]⁺ and [Tf₂N]^?. However, addition of Na⁺/Li⁺, although not significant on its own, produces a dramatic decrease in the partial conductivities of the RTIL ions. The origin of this indirect effect can be traced to the modification of the microscopic structure of the liquid as observed from the radial distribution functions, owing to the formation of [Na(Tf₂N)_n]^(n?1)? and [Li(Tf₂N)_n]^(n?1)? clusters at high concentrations. This formation hinders the motion of the large ions, hence reducing the total conductivity. We demonstrate that this clustering effect is common to both Li and Na, showing that both ions behave in a similar manner at a microscopic level in spite of their distinct ionic radii. This is an interesting finding for extending Li‐ion and Li‐air technologies to their potentially cheaper Na‐based counterparts.     

Synthesis and Photocatalytic Activity of Poly(triazine imide)

Poly(triazine imide) was synthesized with incorporation of Li⁺ and Cl^? ions (PTI/Li⁺Cl^?) to form a carbon nitride derivative. The synthesis of this material by the temperature‐induced condensation of dicyandiamide was examined both in a eutectic mixture of LiCl–KCl and without KCl. On the basis of X‐ray diffraction measurements of the synthesized materials, we suggest that a stoichiometric amount of LiCl is necessary to obtain the PTI/Li⁺Cl^? phase without requiring the presence of KCl at 873 K. PTI/Li⁺Cl^? with modification by either Pt or CoO_x as cocatalyst photocatalytically produced H₂ or O₂, respectively, from water. The production of H₂ or O₂ from water indicates that the valence and conduction bands of PTI/Li⁺Cl^? were properly located to achieve overall water splitting. The treatment of PTI/Li⁺Cl^? with [Pt(NH₃)₄]²⁺ cations enabled the deposition of Pt through ion exchange, demonstrating photocatalytic activity for H₂ evolution, while treatment with [PtCl₆]^2? anions resulted in no Pt deposition. This was most likely because of the preferential exchange between Li⁺ ions and [Pt(NH₃)₄]²⁺ cations.     

Synthesis and crystal structure of 18-crown-6 <Emphasis Type="Italic">E</Emphasis>-2-phenylethenylphosphonic acid diaqua(18-crown-6)sodium <Emphasis Type="Italic">E</Emphasis>-2-phenylethenylphosphonate

New complex compound, diaqua(18-crown-6)sodium E-2-phenylethenylphosphonate 18-crown-6 E-2-phenylethenylphosphonic acid, [Na(18-crown-6)(H₂O)₂]⁺·HO ₃ ^? PCH=CHPh·18-crown-6·H₂O₃PCH=CHPh, was obtained and its crystal and molecular structures were studied by the X-ray structural analysis. In this structure the complex cation [Na(18-crown-6)(H₂O)₂]⁺ is of guest-host type. The coordination polyhedron of its Na⁺ cation is a slightly screwed hexagonal bipyramid with the base consisting of all 6 O atoms of 18-crown-6 ligand and with two opposite apexes at two O atoms of two ligand water molecules. In the studied crystal structure the alternating complex cations and 18-crown-6 molecules as well as the molecules of acid and its anion HO ₃ ^? PCH=CHPh form by means of hydrogen bonds the infinite chains of two different types.     

The heats of formation of some protonated olefinic carbonyl compounds: [C5H9O]+ and [C4H7O2]+ ions

The proton transfer equilibrium reactions involving 3-penten-2-one, 3-methyl-3-buten-2-one, crotonic acid and methacrylic acid were carried out in an ion cyclotron resonance (ICR) spectrometer. The semiempirical method MNDO, used to estimate the heats of formation for 14 protonated [C₅H₉O]⁺ and [C₄H₇O₂]⁺ ions and the energetic aspect of the fragmentations of metastable [C₆H₁₂O]^+. and [C₆H₁₂O₂]^+. ions, leads to the conclusion that the ions corresponding to protonation at the carbonyl oxygen are the most stable. Thus the experimentally determined heats of formation of protonated olefinic carbonyl compounds can be attributed to the following structures: [CH₃COHCHCHCH₃]⁺ (δH_f = 490 KJ mol^?1), [CH₃COHC(CH₃)CH₂]⁺ (δH_f = 502 KJ mol^?1), [HOCOHCHCHCH₃]⁺ (δH_f = 330 KJ mol^?1) and [HOCOHC(CH₃)CH₂]⁺ (δH_f = 336 KJ mol^?1).     

Syntheses and structures of two new lithium-heptamolybdates

The synthesis, crystal structures, IR, UV–vis, ⁷Li NMR spectra, electrochemical investigations, and conductivity studies of two new lithium-heptamolybdates, (NH₄)₄[Li₂(H₂O)₇][Mo₇O₂₄]·H₂O (1) and (NH₄)₃[Li₃(H₂O)₄(μ₆-Mo₇O₂₄)]·2H₂O (2), are reported. In 1 the (NH₄)⁺ and [Li₂(H₂O)₇]²⁺, cations are charge balanced by the heptamolybdate anion. In 2, the [Mo₇O₂₄]^6? anion is coordinated to three unique Li⁺ ions via a μ₆-hexadentate-binding mode resulting in the formation of a two-dimensional (2-D) [Li₃(H₂O)₄(μ₆-Mo₇O₂₄)]^3? anionic complex, charge neutralized by three (NH₄)⁺ ions. The cations, anions, and the lattice water molecules in 1 and 2 are linked by weak H-bonding interactions.     

Formation of Organolithium Hetero‐Aggregates [Li4Ar2(nBu)2] (Ar=C6H4CH(Me)NMe2‐2) during the Directed ortho‐Lithiation of [1‐(Dimethylamino)ethyl]benzene

(R)‐[1‐(Dimethylamino)ethyl]benzene reacts with nBuLi in a 1:1 molar ratio in pentane to quantitatively yield a unique hetero‐aggregate ( 2 a ) containing the lithiated arene, unreacted nBuLi, and the complexed parent arene in a 1:1:1 ratio. As a model compound, [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂] ( 2 b ) was prepared from the quantitative redistribution reaction of the parent lithiated arene Li(C₆H₄CH(Me)NMe₂‐2) with nBuLi in a 1:1 molar ratio. The mono‐Et₂O adduct [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂(OEt₂)] ( 2 c ) and the bis‐Et₂O adduct [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂(OEt₂)₂] ( 2 d ) were obtained by re‐crystallization of 2 b from pentane/Et₂O and pure Et₂O, respectively. The single‐crystal X‐ray structure determinations of 2 b – d show that the overall structural motifs of all three derivatives are closely related. They are all tetranuclear Li aggregates in which the four Li atoms are arranged in an almost regular tetrahedron. These structures can be described as consisting of two linked dimeric units: one Li₂Ar₂ dimer and a hypothetical Li₂nBu₂ dimer. The stereochemical aspects of the chiral Li₂Ar₂ fragment are discussed. The structures as observed in the solid state are apparently retained in solution as revealed by a combination of cryoscopy and ¹H, ¹³C, and ⁶Li NMR spectroscopy.     

catena‐Poly­[[di­aqua­lithium(I)]‐μ‐[9H‐purine‐2,6(1H,3H)‐dionato‐O2:N7]]

In the title compound, [Li(C₅H₃N₄O₂)(H₂O)₂]_n, the coordinate geometry about the Li⁺ ion is distorted tetrahedral and the Li⁺ ion is bonded to N and O atoms of adjacent ligand mol­ecules forming an infinite polymeric chain with Li—O and Li—N bond lengths of 1.901 (5) and 2.043 (6) Å, respectively. Tetrahedral coordination at the Li⁺ ion is completed by two cis water mol­ecules [Li—O 1.985 (6) and 1.946 (6) Å]. The crystal structure is stabilized both by the polymeric structure and by a hydrogen‐bond network involving N—H?O, O—H?O and O—H?N hydrogen bonds.