Ab initio calculations on the interaction of oxygen containing ligands with alkali cations. The system H2CO/Li+

Ab initio calculations on formaldehyde/Li⁺ complexes are presented. The most stable arrangement is characterized by an energy of interaction of 43.2 kcal/mole, C_2v symmetry and an oxygen—lithium distance of R_OLi = 1.77 Å. A detailed analysis of the electron density function gives proof of the electrostatic nature of the complexes H₂O/Li⁺ and H₂Co/Li⁺ and shows extensive mutual polarization. The failure of the semi-empirical method to predict the changes in electron density at the Li⁺ cation correctly is explained.     

Homo‐ and Heterodinuclear Ir and Rh Imine‐functionalized Protic NHC Complexes: Synthetic,Structural Studies,and Tautomerization/Metallotropism Insights

The influence of the potentially chelating imino group of imine‐functionalized Ir and Rh imidazole complexes on the formation of functionalized protic N‐heterocyclic carbene (pNHC) complexes by tautomerization/metallotropism sequences was investigated. Chloride abstraction in [Ir(cod)Cl{C₃H₃N₂(DippN=CMe)‐κN3}] ( 1 a ) (cod=1,5‐cyclooctadiene, Dipp=2,6‐diisopropylphenyl) with TlPF₆ gave [Ir(cod){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 3 a ⁺[PF₆]^?). Plausible mechanisms for the tautomerization of complex 1 a to 3 a ⁺[PF₆]^? involving C2?H bond activation either in 1 a or in [Ir(cod){C₃H₃N₂(DippN=CMe)‐κN3}₂]⁺[PF₆]^? ( 6 a ⁺[PF₆]^?) were postulated. Addition of PR₃ to complex 3 a ⁺[PF₆]^? afforded the eighteen‐valence‐electron complexes [Ir(cod)(PR₃){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 7 a ⁺[PF₆]^? (R=Ph) and 7 b ⁺[PF₆]^? (R=Me)). In contrast to Ir, chloride abstraction from [Rh(cod)Cl{C₃H₃N₂(DippN=CMe)‐κN3}] ( 1 b ) at room temperature afforded [Rh(cod){C₃H₃N₂(DippN=CMe)‐κN3}₂]⁺[PF₆]^? ( 6 b ⁺[PF₆]^?) and [Rh(cod){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 3 b ⁺[PF₆]^?) (minor); the reaction yielded exclusively the latter product in toluene at 110 °C. Double metallation of the azole ring (at both the C2 and the N3 atom) was also achieved: [Ir₂(cod)₂Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 10 ) and the heterodinuclear complex [IrRh(cod)₂Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 12 ) were fully characterized. The structures of complexes 1 b , 3 b ⁺[PF₆]^?, 6 a ⁺[PF₆]^?, 7 a ⁺[PF₆]^?, [Ir(cod){C₃HN₂(DippN=CMe)(DippN=CH)(Me)‐κ²(N3,N_imine)}]⁺[PF₆]^? ( 9 ⁺[PF₆]^?), 10? Et₂O ? toluene, [Ir₂(CO)₄Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 11 ), and 12? 2 THF were determined by X‐ray diffraction.     

The sol–gel chromium-modified V<Subscript>6</Subscript>O<Subscript>13</Subscript> as a cathodic material for lithium batteries

A new V₆O₁₃-based material has been synthesized via the sol–gel route. This sol–gel mixed oxide has been obtained from an appropriate heat treatment of the chromium-exchanged V₂O₅ xerogel performed under reducing atmosphere. This new compound, with the chemical formula Cr_0.36V₆O_13.50, exhibits a monoclinic structure (C2/m) with the following unit cell parameters, a=11.89 Å, b=3.68 Å, c=10.14 Å, β=101.18°. The electrochemical characterization of this compound has been performed using galvanostatic discharge–charge experiments in the potential range 4–1.5 V and completed by ac impedance spectroscopy measurements. It exhibits a specific capacity of about 370 mAh g^?1, which makes the compound Cr_0.36V₆O_13.50 the best one in the V₆O₁₃-based system: 85% of the initial capacity (315 mAh g^?1) after the 35th cycle is still available at C/25 without any polarization. From impedance spectroscopy, a high kinetics of Li transport (D _Li=1.8×10^?9 cm² s^?1) is found at mid-discharge.     

Crystal Structures and Magnetic Properties of Charge-Transfer Salts: Cobaltocenium Bis(cis 1,2-diphenylethene-1,2-dithiolato)metalates (Metal = Ni,Pd, Pt)

Charge-transfer salts [Co(C₅H₅)₂][M(dpt)₂] (M = Ni and Pt; dpt = cis-1,2-diphenylethene-1,2-dithiolate) were synthesized and crystallographically characterized. [Co(C₅H₅)₂][Ni(dpt)2] crystallizes in the monoclinic space group C2/c with a = 25, 607(3) Å, b = 9.4151(11) Å, c = 14.407(4) Å, β = 101.373(22)°, V = 3405.3(10) Å₃ and Z = 4. [Co(C₅H₅)₂][Pt(dpt)₂] belongs to the triclinic space group $ {\rm P}\bar 1 $ with a = 9.4666(11) Å, b = 13.9869(12) Å, c = 14.2652(9) Å, α = 99.983(6)°, β = 90.034(7)°, γ = 109.751(7)°, V = 1747.2(3) ų and Z = 2. Both structures consist of ··· D⁺A^?D⁺A^?D⁺A^? ··· linear chains with the local C₅ axis of the eclipsed [Co(C₅H₅)₂]⁺ cation parallel to the best MS₄ plane of the [M(dpt)₂]^? anion. Magnetic susceptibility measurements show that χ_M T values of the complexes [Co(C₅H₅)₂][M(dpt)₂] (M = Ni, Pd, and Pt) remain nearly constant in the temperature range 15–300 K, but decrease rapidly with further decreasing of temperature, indicating weak antiferromagnetic interactions at low temperatures.     

Kinetic and galvanostatic studies of a polymer electrolyte for lithium-ion batteries

Quaternary polymer electrolyte (PE) based on poly(acrylonitrile) (PAN), 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid (EMImBF₄), sulfolane (TMS) and lithium hexafluorophosphate salt (LiPF₆) (PAN-EMImBF₄-sulfolane-LIPF₆) was prepared by the casting technique. Obtained PE films of ca. 0.2–0.3 mm in thickness showed good mechanical properties. They were examined using scanning electron microscopy (SEM), thermogravimetry (TGA, DSC), the flammability test, electrochemical impedance spectroscopy (EIS) and galvanostatic charging/discharging. SEM images revealed a structure consisting of a polymer network (PAN) and space probably occupied by the liquid phase (LiPF₆ + EMImBF₄ + sulfolane). The polymer electrolyte in contact with an outer flame source did not ignite; it rather underwent decomposition without the formation of flammable products. Room temperature specific conductivity was ca. 2.5 mS cm^?1. The activation energy of the conding process was ca. 9.0 kJ mol^?1. Compatibility of the polymer electrolyte with metallic lithium and graphite anodes was tested applying the galvanostatic method. Charge transfer resistance for the C₆Li → Li⁺ + e^? anode processes, estimated from EIS curve, was ca. 48 Ω. The graphite anode capacity stabilizes at ca. 350 mAh g^?1 after the 30th cycle (20 mA g^?1).     

Structural Characterization of the Solvate Complexes of the Lithium Salts of Diorganophosphides and Phosphinideneborates; A Pathway to Phosphorus-Boron Double Bonds

Abstract

The structures of several solvated lithium diorganophosphides are described. These may take a variety of structures including chain-like polymers with alternating Li⁺ and PR₂ ^? groups, dimeric species with PR₂ ^? groups bridging two Li⁺ ions or mononuclear species having terminal ^?PR₂ groups which have pyramidal geometries at phosphorus. The Li⁺ ions in all structures are solvated by either THF or Et₂O bases. Separation of the Li⁺ can be effected using 12-crown-4 to coordinate Li⁺ as [Li(12-crown-4)₂]⁺ affording free [PR₂]^? counterions. An extension of these techniques has led to the synthesis of the first compounds which have B-P double bonds. These are the compounds [Li(Et₂O)₂PRBMes₂] and [Li(12-crown-4)₂][PRBMes₂](R=Ph, C₆H₁₁,Mes) which have B-P bond lengths of 1.82 – 1.83Å.     

Mechanism of Dissolution of a Lithium Salt in an Electrolytic Solvent in a Lithium Ion Secondary Battery: A Direct Ab Initio Molecular Dynamics (AIMD) Study

The mechanism of dissolution of the Li⁺ ion in an electrolytic solvent is investigated by the direct ab initio molecular dynamics (AIMD) method. Lithium fluoroborate (Li⁺BF₄^?) and ethylene carbonate (EC) are examined as the origin of the Li⁺ ion and the solvent molecule, respectively. This salt is widely utilized as the electrolyte in the lithium ion secondary battery. The binding of EC to the Li⁺ moiety of the Li⁺BF₄^? salt is exothermic, and the binding energies at the CAM–B3LYP/6‐311++G(d,p) level for n=1, 2, 3, and 4, where n is the number of EC molecules binding to the Li⁺ ion, (EC)_n(Li⁺BF₄^?), are calculated to be 91.5, 89.8, 87.2, and 84.0 kcal mol^?1 (per EC molecule), respectively. The intermolecular distances between Li⁺ and the F atom of BF₄^? are elongated: 1.773 Å (n=0), 1.820 Å (n=1), 1.974 Å (n=2), 1.942 Å (n=3), and 4.156 Å (n=4). The atomic bond populations between Li⁺ and the F atom for n=0, 1, 2, 3, and 4 are 0.202, 0.186, 0.150, 0.038, and 0.0, respectively. These results indicate that the interaction of Li⁺ with BF₄^? becomes weaker as the number of EC molecules is increased. The direct AIMD calculation for n=4 shows that EC reacts spontaneously with (EC)₃(Li⁺BF₄^?) and the Li⁺ ion is stripped from the salt. The following substitution reaction takes place: EC+(EC)₃(Li⁺BF₄^?)→(EC)₄Li⁺?(BF₄^?). The reaction mechanism is discussed on the basis of the theoretical results.     

A Theoretical Study of Complex Formation between Formaldehyde and Lithium

Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH₂O/Li⁺, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH₂O^?/Li⁺, the C_2v-conformer of the ²A₁-state with the equilibrium bond distances of d(C? O) = 1.23 Å and d (O? Li) = 1.90 Å is calculated to be more stable than the ₂B₁-state with d (C? O) = 1.34 Å, and d (O? Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed.     

Synthese und Kristallstruktur von KMgCu4V3O13

Synthesis and Crystal Structure of KMgCu₄V₃O₁₃ . Single crystals of KMgCu₄V₃O₁₃ were prepared by supercooled melts. It crystallizes with monoclinic symmetry space group C–P2₁/m (Nr. 11), unit cell dimensions: a = 10.7144 Å, b = 6.0282 Å, c = 8.3365 Å, β = 98.075°, Z = 2. The crystal structure is closely related to the BaMg₂Cu₈O₆O₂₆ type. Cu²⁺ occurs in an unusual trigonal bipyramidal coordination.     

A green strategy for lithium isotopes separation by using mesoporous silica materials doped with ionic liquids and benzo-15-crown-5

Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C₈mim⁺PF₆ ^?, C₈mim⁺BF₄ ^? or C₈mim⁺NTf ₂ ^? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N₂ gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope ⁷Li was concentrated in the solution phase while the lighter isotope ⁶Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of ⁶Li–⁷Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li_0.5)₂(B15)₂(H₂O)]⁺ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L^?1 HCl and reused in the consecutive removal of lithium ion in five cycles.     

Conformational Studies of Dibenzo-30-crown-10 Complexes. Syntheses and Crystal Structures of Potassium and Ammonium Hexafluorophosphate Complexes

Abstract

Crown ether complexes formed by the dibenzo–30-crown–10 (DB30C10) with potassium and ammonium hexafluorophosphate have been prepared and their crystal structures have been determined by single crystal X-ray analyses. The potassium complex (compound 1) consists of [K(DB30C10)]⁺ cation and PF₆ ^? anion. Crystals are monoclinic, space group P2/n, with a = 11.9106(3), b = 9.8382(5), c = 14.3062(3) Å, β = 97.581(3)°, V = 1661.7(1) ų, D_c = 1.440 g cm^?3, Z = 4, R = 0.0675 for 2528 unique observed reflections. The potassium atom is coordinated to the ten oxygen atoms of the crown ligand at the distance from 2.859(3) to 2.930(3) Å. The ammonium complex (compound 2) has also 1:1 crown—cation ratio. Crystals are monoclinic, space group P2₁/n, with a = 12.5061(6), b = 19.3724(5), c = 14.2203(9) Å, β = 102.476(5)°, V = 3363.8(3) ų, D_c = 1.501 g cm^?3, Z = 4, R = 0.0677 for 4172 unique observed reflections. The ammonium cation is completely enclosed with crown oxygen atoms forming seven hydrogen bonds. The conformation of previously reported dibenzo-30-crown-10 complexes with potassium salts were investigated using polar coordinate maps.     

Supramolecular Formation of Li+@PCBM Fullerene with Sulfonated Porphyrins and Long‐Lived Charge Separation

Lithium‐ion‐encapsulated [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester fullerene (Li⁺@PCBM) was utilized to construct supramolecules with sulfonated meso‐tetraphenylporphyrins (MTPPS^4?; M=Zn, H₂) in polar benzonitrile. The association constants were determined to be 1.8×10⁵ M ^?1 for ZnTPPS^4?/Li⁺@PCBM and 6.2×10⁴ M ^?1 for H₂TPPS^4?/Li⁺@PCBM. From the electrochemical analyses, the energies of the charge‐separated (CS) states were estimated to be 0.69 eV for ZnTPPS^4?/Li⁺@PCBM and 1.00 eV for H₂TPPS^4?/Li⁺@PCBM. Upon photoexcitation of the porphyrin moieties of MTPPS^4?/Li⁺@PCBM, photoinduced electron transfer occurred to produce the CS states. The lifetimes of the CS states were 560 μs for ZnTPPS^4?/Li⁺@PCBM and 450 μs for H₂TPPS^4?/Li⁺@PCBM. The spin states of the CS states were determined to be triplet by electron paramagnetic resonance spectroscopy measurements at 4 K. The reorganization energies (λ) and electronic coupling term (V) for back electron transfer (BET) were determined from the temperature dependence of k_BET to be λ=0.36 eV and V=8.5×10^?3 cm^?1 for ZnTPPS^4?/Li⁺@PCBM and λ=0.62 eV and V=7.9×10^?3 cm^?1 for H₂TPPS^4?/Li⁺@PCBM based on the Marcus theory of nonadiabatic electron transfer. Such small V values are the result of a small orbital interaction between the MTPPS^4? and Li⁺@PCBM moieties. These small V values and spin‐forbidden charge recombination afford a long‐lived CS state.     

Brush‐First ROMP of poly(ethylene oxide) macromonomers of varied length: impact of polymer architecture on thermal behavior and Li+ conductivity

The properties of polymeric materials are dictated not only by their composition but also by their molecular architecture. Here, by employing brush‐first ring‐opening metathesis polymerization (ROMP), norbornene‐terminated poly(ethylene oxide) (PEO) macromonomers ( MM‐n , linear architecture), bottlebrush polymers ( Brush‐n , comb architecture), and brush‐arm star polymers ( BASP‐n , star architecture), where n indicates the average degree of polymerization (DP) of PEO, are synthesized. The impact of architecture on the thermal properties and Li⁺ conductivities for this series of PEO architectures is investigated. Notably, in polymers bearing PEO with the highest degree of polymerization, irrespective of differences in architecture and molecular weight (~100‐fold differences), electrolytes with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an Li⁺ source exhibit normalized ionic conductivities (σ_n) within only 4.9 times difference (σ_n = 29.8 × 10^?5 S cm^?1 for MM‐45 and σ_n = 6.07 × 10^?5 S cm^?1 for BASP‐45 ) at a concentration of Li⁺ r = [Li⁺]/[EO] = 1/12 at 50 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 448–455     

Li-NMR study of the stoichiometry, stability and exchange kinetics of Li ion with 12-Crown-4, 15-Crown-5 and cryptands C222, C221 and C211 in 50% ionic liquid-acetonitrile mixtures

⁷Li-NMR spectroscopy was used to study the complexation of Li⁺ ion with 12C4, 15C5, C222, C221, C211 in acetonitrile (AN) and its 50% (wt/wt) mixtures with two new room temperature ionic liquids, 1-ethyl-3-methylimidazolium hexafluorophosphate (EMim PF₆) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMim BF₄) at 298 K. Excluding the cases of Li⁺-C211 in all solvents and Li⁺-C221 in AN and 50% (wt/wt) AN-EMim PF₆, in other cases, the exchange between free and 1:1 complexed Li⁺ was fast on the NMR time scale and only a single population average ⁷Li signal was observed. Formation constants of the resulting 1:1 complexes were evaluated by computer fitting of the chemical shift-mole ratio data and integration of two ⁷Li signals. All complexes in EMim PF₆ were found to be more stable than those in EMim BF₄. ⁷Li-NMR line-shape analysis was used to determine the kinetic parameters and the mechanism for the chemical exchange of Li⁺ between the free and 1:1 complex with C221 in 50% (wt/wt) AN-EMim PF₆ mixtures solution. By comparing our study with the previous one, it is derived that, increasing the percentage of ion liquid in acetonitrile, changes the mechanism and decrease the exchange rate constant of Li⁺ ion between free and complex sites.     

Transferring Lithium Ions in Nanochannels: A PEO/Li+ Solid Polymer Electrolyte Design

A new category of crystalline polymer electrolyte prepared by the supramolecular self‐assembly of polyethylene oxide (PEO), α‐cyclodextrin (α‐CD), and LiAsF₆ is reported. The polymer electrolyte consists of the nanochannels formed by α‐CDs in which the PEO/Li⁺ complexes are confined. The nanochannels formed by α‐CD provide the pathway for the directional motion of Li⁺ ions and at the same time prevent the access of the anions by size exclusion, resulting in good separation of the Li⁺ ions and the anions. The conductivity of the reported material is 30 times higher than that of the comparable PEO/Li⁺ complex crystal at room temperature. By using state‐of‐art solid‐state NMR spectroscopy, the structure and dynamics of the material were investigated in detail. The dynamics of the Li⁺ ions was studied and correlated to the ionic conductivity of the material.     

1‐Methyl‐4‐nitraminopyridinium nitrate and 4‐nitraminopyridinium methanesulfonate

In the title compounds, C₆H₈N₃O₂⁺·NO₃^? and C₅­H₆­N₃­O₂⁺·­CH₃SO₃^?, respectively, the cations are almost planar; the twist of the nitr­amino group about the C—N and N—N bonds does not exceed 10°. The deviations from coplanarity are accounted for by intermolecular N—H?O interactions. The coplanarity of the NHNO₂ group and the phenyl ring leads to the deformation of the nitr­amino group. The C—N—N angle and one C—C—N angle at the junction of the phenyl ring and the nitr­amino group are increased from 120° by ca 6°, whereas the other junction C—C—N angle is decreased by ca 5°. Within the nitro group, the O—N—O angle is increased by ca 5° and one O—N—N angle is decreased by ca 5°, whereas the other O—N—N angle remains almost unchanged. The cations are connected to the anions by relatively strong N—H?O hydrogen bonds [shortest H?O separations 1.77 (2)–1.81 (3) Å] and much weaker C—H?O hydrogen bonds [H?O separations 2.30 (2)–2.63 (3) Å].     

Electrostatic,sequential bond energies and structures of Li+·(N2)n complexes: computational study

The MP2 and CCSD calculations of the geometries and binding energies of the Li⁺·(N₂)_n (n?=?1–4) complexes are obtained. The potential energy surface showed that these complexes exhibit one minimum state and one transition state. The mono- and di-ligated complexes exhibit linear configurations with a binding energy of 11.1 and 21.2 kcal mol^?1, respectively. Trigonal planar and tetrahedral configurations are obtained for tri- and tetra-ligated complexes, respectively. The computed sequential bond dissociation energies (BDEs) of Li⁺·(N₂)_n (n?=?1–4) complexes are also calculated in which the mono-ligated complex has the largest BDE value. The obtained trend is mainly dependent on the variation in the ion-quadrupole interaction of these ion complexes. These calculations predict that these complexes are of purely electrostatic nature.

     

One-pot synthesis of cis-bis(2,2′-bipyridine)carbonylruthenium(II) complexes from a carbonato precursor: X-ray crystal structures and electron transfer processes of the series complexes

The reaction of Brønsted acids with cis-[Ru(bpy)₂(CO₃)] (bpy?=?2,2′-bipyridine) under CO results in cleavage of the carbonato ligand and formation of cationic cis-[Ru(bpy)₂(CO)L] ^{n +} complexes [L?=?ONO₂ (1 ⁺), OH₂ (2 ²⁺), Cl (3 ⁺), OCOH (4 ⁺), and OCOCH₃ (5 ⁺)]. The structures of 1 ⁺ and 2 ²⁺ were confirmed by single-crystal X-ray diffraction. Crystal data for 1(PF₆): monoclinic, P2₁/c, a?=?10.5242(3), b?=?15.4727(3), c?=?14.6571(3) Å, β?=?92.3219(9)°, V?=?2384.77(9) ų, Z?=?4, D _calcd?=?1.806?g cm^?3, 5460 unique reflections (R _int?=?0.032), R ₁?=?0.0540 [I?>?2σ(I)], wR ₂?=?0.1642 (all reflections); crystal data for 2(ClO₄)₂?·?H₂O: monoclinic, C2/c, a?=?20.4247(7), b?=?10.0777(3), c?=?15.6039(5) Å, β?=?127.7569(8)°, V?=?2539.31(14) ų, Z?=?4, D _calcd?=?1.769?g cm^?3, 2895 unique reflections (R _int?=?0.036), R ₁?=?0.0343 [I?>?2σ(I)], wR ₂?=?0.0907 (all reflections). Except for 2(PF₆)₂ the complexes exhibit oxidation at 1.02–1.30?V versus Fc⁺/Fc in acetonitrile. Bipyridine-centered reductions are also observed; these redox potentials depend on the nature of L. This convenient synthesis will be useful for producing cis-[Ru(bpy)₂(CO)L] ^{n +}-type complexes in high yield.     

Some ring replacement and nucleophilic substitution reactions of η6-subsituted arene-η5-cylopentadienyliron hexafluorophosphates

A number of nitroarene and aminoarene complexes, including the PF₆^? salts of NO₂C₆H₅FeCp^p+, 0-, m- or p-CH₃(NO₂)C₆H₄FeCp⁺, NH₂C₆H₅FeCp^p+ and 0-, m-, orp-CH₃(NH₂)C₆H₄FeCp^p+, when heated with an excess of P(OC₂H₅)₃ all gave rise to the ring replacement product, CpFe(P(OC₂H₅)₃)₃⁺ PF₆^? (I). Similarly, the thermal reaction of NO₂C₆H₅Fe(CH₃)Cp⁺ PF₆^? or NH₂C₆H₅Fe(CH₃)Cp⁺ PF₆^? with P(OC₂H₅)₃ gave CH₃CpFe(P(OC₂H₅)₃)₃⁺ PF₆^? (VII). With m-CH₃(Cl)C₆H₄-FeCp⁺ PF₆^? (XIV), heating with P(OC₂H₅)₃ also gave rise to I, while the same treatment with P(OC₂H₅)₃ at room temperature in CH₂Cl₂ showed no nucleophilic substitution of the chlorine atom of XIV by P(OC₂H₅)₃. On the other hand, the chlorine atom of a number of chloroarene complexes could be readily displaced at room temperature with various amines acting as nucleophiles. Such nucleophilic substitutions were carried out on ClC₆H₅FeCp⁺ PF₆^? and 0-, m- or p-CH₃(CI)C₆H₄FeCp⁺ PF₆^? with methylamine, ethylenediamine, cyclohexylamine, benzylamine and pyrrolidine to give rise to 20N-substituted aminoarene complexes.     

Polyphosphonates as ionic conducting polymers

Polyphosphonates, a class of polymers with the generic formula –[P(R)(X)–OR'O]_n–, exhibit a high degree of modularity due to the range of R, R', and X groups that can be incorporated. As such, these polymers may be designed with a polyethylene oxide (PEO) backbone (R' group) and employed as solid polymer electrolytes (SPEs). Two PEO-containing polyphosphonate analogs (R = Ph; X = S or Se) were doped with LiPF₆ and their conductivities were measured. Conductivities were similar (X = S) to or exceeding (X = Se) those of standard PEO systems (just below 10⁻⁴ S/cm at 100°C). Binding models for Li⁺ were generated using ³¹P{¹H}NMR titration experiments. Binding of Li⁺ by these polyphosphonates followed a positive cooperativity model, and varying the X group (S or Se) affected the observed cooperativity (Hill coefficient = 1.73 and 4.16, respectively). The presence of Se also leads to an increase in conductivity as temperature is raised above the T_g, which is likely an effect of reduced Columbic interactions. Because of their modularity and ease with which cation binding can be evaluated using ³¹P{¹H} NMR titration experiments, polyphosphonates offer a unique approach for the modification of Li⁺ ion battery technology.