Rational Synthesis,Structures and Properties of the Ionic Liquid Binary Iodine-Bromine Octahalide Series [InBr8−n]2− (n=0, 2, 3, 4)

A series of octanuclear iodine-bromine interhalides [I_nBr_8−n]²⁻ (n=0, 2, 3, 4) were prepared systematically in two steps. Firstly, addition of a dihalogen (Br₂ or IBr) to the triaminocyclopropenium bromide salt [C₃(NEt₂)₃]Br forms the corresponding trihalide salt with Br₃⁻ or IBr₂⁻ anions, respectively. Secondly, addition to Br₃⁻ of half an equivalent of Br₂ gives the octabromine polyhalide [Br₈]²⁻, whereas addition to IBr₂⁻ of half an equivalent of Br₂, IBr or I₂ gives the corresponding interhalides: [I₂Br₆]²⁻, [I₃Br₅]²⁻, and [I₄Br₄]²⁻, respectively. The four octahalides were characterized by X-ray crystallography, computational studies, Raman and Far-IR spectroscopies, as well as by TGA and melting point. All of the salts were found to be ionic liquids.     

Kinetic study of the reactions Br + IBr→I + Br2 and I + Br2→Br + IBr

The kinetics of the title reactions have been studied using the discharge-flow mass spectrometic method at 296 K and 1 torr of helium. The rate constant obtained for the forward reaction Br+IBr→I+Br₂ (1), using three different experimental approaches (kinetics of Br consumption in excess of IBr, IBr consumption in excess of Br, and I formation), is: k₁=(2.7±0.4)×10⁻¹¹ cm³ molecule⁻¹s⁻¹. The rate constant of the reverse reaction: I+Br₂→Br+IBr (−1) has been obtained from the Br₂ consumption rate (with an excess of I atoms) and the IBr formation rate: k₋₁=(1.65±0.2)×10⁻¹³ cm³molecule⁻¹s⁻¹. The equilibrium constant for the reactions (1,−1), resulting from these direct determinations of k₁ and k₋₁ and, also, from the measurements of the equilibrium concentrations of Br, IBr, I, and Br₂, is: K₁=k₁/k₋₁=161.2±19.7. These data have been used to determine the enthalpy of reaction (1), ΔH₂₉₈°=−(3.6±0.1) kcal mol⁻¹ and the heat of formation of the IBr molecule, ΔH_f,298°(IBr)=(9.8±0.1) kcal mol⁻¹. © 1998 John Wiley & sons, Inc. Int J Chem Kinet 30: 933–940, 1998     

Reaction of organochromium cations with iodine monobromide

Several members of the family of (H₂O)₅CrR²⁺ complexes have been shown to react cleanly with the interhalogen molecule IBr. Products of reaction are exclusively the organic iodide RI, Cr(H₂O)₆³⁺, and Br^?-; RBr and (H₂O)₅CrB²⁺ are not formed. Rates of the IBr reactions are comparable to those of bromine and much higher than those of iodine. These results are consistent with electrophilic reactions and suggest an S_E2 mechanism.     

Construction of Ternary Iodine–Bromine–Chlorine Octahalides

A series of five ternary octanuclear iodine-bromine-chlorine interhalides, [I₂Br₂Cl₄]²⁻ ( 1 ), [I₃BrCl₄]²⁻ ( 2 ), [I₄Br₂Cl₂]²⁻ ( 3 ), [I₂Br₄Cl₂]²⁻ ( 4 ) and [I₃Br₃Cl₂]²⁻ ( 5 ), have been rationally constructed in two steps. Firstly, addition of a dihalogen (ICl or IBr) to the triaminocyclopropenium chloride salt [C₃(NEt₂)₃]Cl forms the corresponding trihalide salt with [ICl₂]⁻ or [BrICl]⁻ anions, respectively. Secondly, addition of a half-equivalent of a second dihalogen, followed by crystallization at low temperature, gives the corresponding octahalide: addition of Br₂ and IBr to [ICl₂]⁻ gives 1 and 2 , respectively, whereas addition of I₂, Br₂ and IBr to [BrICl]⁻ gives 3 , 4 and 5 , respectively. The five octahalides were characterized by X-ray crystallography and far–IR spectroscopy.     

The Studies of the Resonance Raman Scattering and the Chemical Reactions Involved in the Gaseous Iodine Bromide Under Argon Ion Laser Light

The resonance Raman spectra of gaseous iodine bromide IBr have been studied with the excitation of various argon ion laser lines from 5017 to 4579Å. The fine structures of the fundamental and few overtones of IBr are also studied by various power of 4880Å laser line. The resonance Raman scattering is found to be strong as that of Br₂ and ICI. A new term “apparent spectroscopic temperature” is suggusted for the case of the resonance Raman scattering. The apparent spectroscopic temperatures measured in this cell show that the system is not in thermal equilibrium. Br₂ is the hottest and I₂ is the coldest. IBr is in the middle. Unfortunately, no chemical reaction enhanced phenomenon is found although there should be some chemical reactions occurring under the laser light. The initiating reaction is the photodissociation of the main component IBr which also has large absorptivity. Because of the non-crossing between the B³Π and the ¹Π states, the primary products of the photodissociation should be I and Br. The chemical reactions of I and Br with IBr follow. The reactions of I and IBr is endothermic but the reaction of Br with IBr is exothermic. Therefore vibrational hot Br₂ is produced and its apparent spectroscopic temperature should be higher. On the other hand, the apparent spectroscopic temperature of I₂ is lower.     

Experimental and Computational Probes of the Nature of Halogen Bonding: Complexes of Bromine‐Containing Molecules with Bromide Anions

The nature of halogen bonding is examined via experimental and computational characterizations of a series of associates between electrophilic bromocarbons R? Br (R? Br=CBr₃F, CBr₃NO₂, CBr₃COCBr₃, CBr₃CONH₂, CBr₃CN, etc.) and bromide anions. The [R? Br, Br^?] complexes show intense absorption bands in the 200–350 nm range which follow the same Mulliken correlation as those observed for the charge‐transfer associates of bromide anions with common organic π‐acceptors. For a wide range of the associates, intermolecular R? Br???Br^? separations decrease and intramolecular C? Br bond lengths increase proportionally to the Br^?→R? Br charge transfer; and the energies of R? Br???Br^? bonds are correlated with the linear combination of orbital (charge‐transfer) and electrostatic interactions. On the whole, spectral, structural and thermodynamic characteristics of the [R? Br, Br^?] complexes indicate that besides electrostatics, the orbital (charge‐transfer) interactions play a vital role in the R? Br???Br^? halogen bonding. This indicates that in addition to controlling the geometries of supramolecular assemblies, halogen bonding leads to electronic coupling between interacting species, and thus affects reactivity of halogenated molecules, as well as conducting and magnetic properties of their solid‐state materials.     

Transformation of spin-orbit excited states of halogen atoms in the chemical reactions F + Br2 → BrF + Br,I*+ Br2 → IBr + Br,and Br + IBr → Br2 + I

The small laser pulse gain method, based on photochemical Br and I lasers, is used to probe ²P_3/2 and ²P_1/2 states of iodine and bromine atoms in the reactions F + Br₂ → BrF + Br (I), I(²P_1/2) + Br₂ → IBr + Br (II), and Br + IBr → Br₂ + I (III). The results obtained are capable of formulating a conservation rule for the spin-orbit excited state.     

An XPS investigation of silver bromide-coated ion-selective electrodes

XPS data of AgBr-coated ion-selective electrodes exposed to high concentrations of Ag⁺, Cl⁻, Br⁻, I⁻, and NH₃ revealed a change in the surface properties of the original electrode. A 40 min to one week exposure of the silver bromide ion-selective electrode surface to solutions containing high concentrations of chloride ions leads to the formation of a mixed halide layer, as the chloride ions are incorporated in the surface. Exposure to high concentrations of iodide-containing solutions results in a new silver iodide layer on top of the original silver bromide laver. Silver ions diffuse to the newly formed layers. NH₃ results in the rapid degradation of the AgBr surface as the diamine complex, Ag(NH₃)⁺₂, is formed.     

Conductivity and Redox Potentials of Ionic Liquid Trihalogen Monoanions [X3]−, [XY2]−, and [BrF4]− (X=Cl,Br, I and Y=Cl,Br)

The ionic liquid (IL) trihalogen monoanions [N₂₂₂₁][X₃]⁻ and [N₂₂₂₁][XY₂]⁻ ([N₂₂₂₁]⁺=triethylmethylammonium, X=Cl, Br, I, Y=Cl, Br) were investigated electrochemically via temperature dependent conductance and cyclic voltammetry (CV) measurements. The polyhalogen monoanions were measured both as neat salts and as double salts in 1-butyl-1-methyl-pyrrolidinium trifluoromethane-sulfonate ([BMP][OTf], [X₃]⁻/[XY₂]⁻ 0.5 M). Lighter IL trihalogen monoanions displayed higher conductivities than their heavier homologues, with [Cl₃]⁻ being 1.1 and 3.7 times greater than [Br₃]⁻ and [I₃]⁻, respectively. The addition of [BMP][OTf] reduced the conductivity significantly. Within the group of polyhalogen monoanions, the oxidation potential develops in the series [Cl₃]⁻>[BrCl₂]⁻>[Br₃]⁻>[IBr₂]⁻>[ICl₂]⁻>[I₃]⁻. The redox potential of the interhalogen monoanions was found to be primarily determined by the central halogen, I in [ICl₂]⁻ and [IBr₂]⁻_, and Br in [BrCl₂]⁻. Additionally, tetrafluorobromate(III) ([N₂₂₂₁]⁺[BrF₄]⁻) was analyzed via CV in MeCN at 0 °C, yielding a single reversible redox process ([BrF₂]⁻/[BrF₄]⁻).     

Three-Electron Transfer-Based High-Capacity Organic Lithium-Iodine (Chlorine) Batteries

Conversion-type batteries apply the principle that more charge transfer is preferable. The underutilized electron transfer mode within two undermines the electrochemical performance of halogen batteries. Here, we realised a three-electron transfer lithium-halogen battery based on I⁻/I⁺ and Cl⁻/Cl⁰ couples by using a common commercial electrolyte saturated with Cl⁻ anions. The resulting Li||tetrabutylammonium triiodide (TBAI₃) cell exhibits three distinct discharging plateaus at 2.97, 3.40, and 3.85 V. Moreover, it has a high capacity of 631 mAh g⁻¹_I (265 mAh g⁻¹_electrode, based on entire mass loading) and record-high energy density of up to 2013 Wh kg⁻¹_I (845 Wh kg⁻¹_electrode). To support these findings, experimental characterisations and density functional theory calculations were conducted to elucidate the redox chemistry involved in this novel interhalogen strategy. We believe our paradigm presented here has a foreseeable inspiring effect on other halogen batteries for high-energy-density pursuit.     

Inhibition of chemical oscillations by bromide ion in the Briggs–Rauscher reaction

The addition of bromide ions to the component solutions of the Briggs– Rauscher oscillating system produces a variety of phenomena, depending on the sequence of the addition and on the initial bromide concentration. If the addition is made some minutes after the mixing of H₂O₂ and acidic IO₃⁻ and before adding malonic acid and Mn²⁺ ions, the oscillations last for five or six cycles, then suddenly ceases. If the addition is made immediately after the mixing of H₂O₂ and acidic IO₃⁻ and before adding malonic acid and Mn²⁺ ions, the oscillations do not start at all. The addition of bromide ions to an actively oscillating BR reaction causes a rapid suppression of the oscillations. Our observations may be accounted for by a mechanism involving the IBr species. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 641–646, 1998     

Kinetics of osmium(VIII) catalyzed oxidation of allyl alcohol by potassium bromate in aqueous acidic medium‐autocatalysis in catalysis

The kinetics of oxidation of allyl alcohol with potassium bromate in the presence of osmium(VIII) catalyst in aqueous acid medium has been studied under varying conditions. The active species of oxidant and catalyst in the reaction were understood to be Bro₃⁻ and H₂OsO₅, respectively. The autocatalysis exhibited by one of the products, that is, Br⁻, was attributed to complex formation between bromide and osmium(VIII). A composite scheme and rate law were possible. Some reaction constants involved in the mechanism have been evaluated. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 583–589, 1999     

Metal Oxide Nanostructures Generated from In Situ Sacrifice of Zinc in Bimetallic Textures as Flexible Ni/Fe Fast Battery Electrodes

An “in situ sacrifice” process was devised in this work as a room‐temperature, all‐solution processed electrochemical method to synthesize nanostructured NiO_x and FeO_x directly on current collectors. After electrodepositing NiZn/FeZn bimetallic textures on a copper net, the zinc component is etched and the remnant nickel/iron are evolved into NiO_x and FeO_x by the “in situ sacrifice” activation we propose. As‐prepared electrodes exhibit high areal capacities of 0.47 mA h cm⁻² and 0.32 mA h cm⁻², respectively. By integrating NiO_x as the cathode, FeO_x as the anode, and poly(vinyl alcohol) (PVA)‐KOH gel as the separator/solid‐state electrolyte, the assembled quasi‐solid‐state flexible battery delivers a volumetric capacity of 6.91 mA h cm⁻³ at 5 mA cm⁻², along with a maximum energy density of 7.40 mWh cm⁻³ under a power density of 0.27 W cm⁻³ and a maximum tested power density of 3.13 W cm⁻³ with a 2.17 mW h cm⁻³ energy density retention. Our room‐temperature synthesis, which only consumes minute electricity, makes it a promising approach for large‐scale production. We also emphasize the in situ sacrifice zinc etching process used in this work as a general strategy for metal‐based nanostructure growth for high‐performance battery materials.     

Coincidence studies of fluorescence and dissociation processes in electronic excited states of I2+, Br2+, IBr+ and ICl+

The PIFCO technique in which mass-selected photoion—fluorescence photon coincidences are counted, was used to investigate whether I₂⁺, IBr⁺ and ICl⁺ fluoresce. Measurements were made of lifetimes and fluorescence quantum yields of electronic excited states of these ions. Emission was discovered for I₂⁺ and IBr⁺, but ICl⁺ apparently does not fluoresce. Information on the radiative properties of Br₂⁺ was obtained as a by-product of the work on IBr⁺. Fragment ion kinetic energy releases were determined and provide information on dissociative ionization processes in the halogen and interhalogen ions studied.     

The double-layered hydro­xide 3CaO·Al2O3·0.5CaBr2·0.5CaCl2·10H2O

The title compound, calcium oxide–dialuminium trioxide–calcium dibromide–calcium dichloride hydrate (3/1/0.5/0.5/10), also formulated as Ca₂Al(OH)₆Br_0.478Cl_0.522·2H₂O (dicalcium aluminium hydro­xide hemibromide hemichloride dihydrate), is a double-layered hydro­xide which belongs to the solid solution Ca₂Al(OH)₆Br_xCl_1−x·2H₂O, where x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br_0.5Cl_0.5·2H₂O]⁻ share statistically the same crystallographic site. Al³⁺ and Ca²⁺ cations are coordinated by six and seven O atoms, respectively. All water mol­ecules are bonded to Ca²⁺ cations and assume the seventh coordination position. Anions in the interlayer are surrounded by ten H atoms. Br⁻ and Cl⁻ are therefore connected to the main layer by ten hydrogen bonds, six of 2.74 (2) Å and four of 2.52 (5) Å, where the donors are hydroxyl groups and water mol­ecules, respectively. Like the chloride equivalent, the title compound is a 6R polytype with trigonal space group Rc and lattice parameters a = 5.7537 (4) Å and c = 48.108 (4) Å.     

2,2′‐Bipyridinium(1+) bromide monohydrate

In the crystal structure of 2,2′‐bipyridinium(1+) bromide monohydrate, C₁₀H₉N₂⁺·Br⁻·H₂O, the cation has a cisoid conformation with an intramolecular N—H⋯N hydrogen bond. The cation also forms an N—H⋯O hydrogen bond to an adjacent water mol­ecule, which in turn forms O—H⋯Br⁻ hydrogen bonds to adjacent Br⁻ anions. In this way, a chain is formed extending along the b axis. Additional interactions (C—H⋯Br⁻ and π–π) serve to stabilize the structure further.     

The chloride,bromide and iodide salts of 1‐(diaminomethylene)thiouron‐1‐ium

Crystals of 1‐(diaminomethylene)thiouron‐1‐ium chloride, C₂H₇N₄S⁺·Cl⁻, 1‐(diaminomethylene)thiouron‐1‐ium bromide, C₂H₇N₄S⁺·Br⁻, and 1‐(diaminomethylene)thiouron‐1‐ium iodide, C₂H₇N₄S⁺·I⁻, are built up from the nonplanar 1‐(diaminomethylene)thiouron‐1‐ium cation and the respective halogenide anion. The conformation of the 1‐(diaminomethylene)thiouron‐1‐ium cation in each case is twisted. Both arms of the cation are planar and rotated in opposite directions around the C—N bonds involving the central N atom. The dihedral angles describing the twisted conformation are 22.9 (1), 15.2 (1) and 4.2 (1)° in the chloride, bromide and iodide salts, respectively. Ionic and extensive hydrogen‐bonding interactions join oppositely charged units into a supramolecular network. The aim of the investigation is to study the influence of the size of the ionic radii of the Cl⁻, Br⁻ and I⁻ ions on the dimensionality of the hydrogen‐bonding network of the 1‐(diaminomethylene)thiouron‐1‐ium cation. The 1‐(diaminomethylene)thiouron‐1‐ium system should be of use in crystal engineering to form multidimensional networks.     

Boosting Electroreduction of CO2 over Cationic Covalent Organic Frameworks: Hydrogen Bonding Effects of Halogen Ions

We present the first example of charged imidazolium functionalized porphyrin-based covalent organic framework (Co-iBFBim-COF-X) for electrocatalytic CO₂ reduction reaction, where the free anions (e.g., F⁻, Cl⁻, Br⁻, and I⁻) of imidazolium ions nearby the active Co sites can stabilize the key intermediate *COOH and inhibit hydrogen evolution reaction. Thus, Co-iBFBim-COF-X exhibits higher activity than the neutral Co-BFBim-COF, following the trend of F⁻<Cl⁻<Br⁻<I⁻. Particularly, the Co-iBFBim-COF-I⁻ showed nearly 100 % CO₂ selectivity at a low full-cell voltage of 2.3 V, and achieved a high CO₂ partial current density of 52 mA cm⁻² with a turnover frequency of 3018 h⁻¹ at 2.4 V in the anion membrane electrode assembly, which is 3.57 times larger than that of neutral Co-BFBim-COF. This work provides new insight into the importance of free anions in the stabilization of intermediates and decreasing the local binding energy of H₂O with active moiety to enhance CO₂ reduction reaction.     

Studies on the oxidation of α-amino acids by N-Bromo oxidants: Kinetics of the reaction of bromide ion with N-Bromoacetamide

The rate of oxidation of amino acids (AA) by N-Bromoacetamide (NBA) was studied in aqueous buffered medium at 35°C. The rate of disappearance of [NBA] is catalyzed by the Br⁻ produced from the reduction of NBA. Analysis of the autocatalyzed reaction gives the kinetic data for the oxidation of bromide ion by NBA. The results suggest that the protonated NBA reacts with Br⁻ to form Br₂ which rapidly oxidizes amino acids. The rate constant for the reaction between protonated NBA and Br⁻ at 35°C is estimated. © 1996 John Wiley & Sons, Inc.     

Quasi-Solid Sulfur Conversion for Energetic All-Solid-State Na−S Battery

The high theoretical energy density (1274 Wh kg⁻¹) and high safety enable the all-solid-state Na−S batteries with great promise for stationary energy storage system. However, the uncontrollable solid–liquid-solid multiphase conversion and its associated sluggish polysulfides redox kinetics pose a great challenge in tunning the sulfur speciation pathway for practical Na−S electrochemistry. Herein, we propose a new design methodology for matrix featuring separated bi-catalytic sites that control the multi-step polysulfide transformation in tandem and direct quasi-solid reversible sulfur conversion during battery cycling. It is revealed that the N, P heteroatom hotspots are more favorable for catalyzing the long-chain polysulfides reduction, while PtNi nanocrystals manipulate the direct and full Na₂S₄ to Na₂S low-kinetic conversion during discharging. The electrodeposited Na₂S on strongly coupled PtNi and N, P-codoped carbon host is extremely electroreactive and can be readily recovered back to S₈ without passivation of active species during battery recharging, which delivers a true tandem electrocatalytic quasi-solid sulfur conversion mechanism. Accordingly, stable cycling of the all-solid-state soft-package Na−S pouch cells with an attractive specific capacity of 876 mAh g_S⁻¹ and a high energy of 608 Wh kg_cathode⁻¹ (172 Wh kg⁻¹, based on the total mass of cathode and anode) at 60 °C are demonstrated.