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A catalyst to electrochemically decompose lithium fluoride (LiF), which is abound in the electrode of the spent LiBs, was studied to develop a Li reproduction technology. Since the oxidizing activity of halogen I₂, Br₂, Cl₂, or F₂, increases, the reaction I₂ + 2LiF → F₂ + 2LiI cannot proceed. We examined the catalytic activity of interhalogens such as iodine monobromide (IBr) and iodine chloride (ICl) for LiF decomposition in specific organic solvents. We observed the chemical decomposition of LiF in IBr and ICl dimethyl sulfoxide (DMSO) solutions. This decomposition was induced by an increase in solution acidity, accompanied by a large deviation in the electric charge between two halogen elements due to the complex formation of interhalogen with DMSO. A double-chamber-type cell for Li recovery from LiF was constructed by combining this LiF decomposition behavior with redox coupling of IBr or ICl operated by electrical charging. The cell was first demonstrated to be chargeable due to the continuous decomposition of LiF.

A panoramic view of photodissociation As light pulses get shorter in time, they correspondingly get broader in frequency. Kobayashi et al. take advantage of both properties of attosecond pulses to elucidate iodine monobromide (IBr) photodissociation by detecting ultrafast bromine and iodine spectral shifts simultaneously. A preliminary burst of light weakens the I–Br bond. Then, as the atoms fly apart, they reach a configuration where the bond vibration can couple ground and excited electronic states. The broadband probe pulse reveals rapid changes in each atom's electronic structure at this juncture. Science , this issue p. 79

A simple and efficient method for regioselective synthesis of 3-arylquinolines is described from α-aminoacetophenones and trans-β-nitrostyrenes using 20 mol% iodine monobromide as a catalyst in acetonitrile solvent at 80 °C. The present method involves tandem reaction of α-aminoacetophenones and trans-β-nitrostyrenes, formation of two new C-C bonds and cleavage of one C-C bond in a single step. The salient features of the protocol are metal- and oxidant-free reaction conditions, broad substrate scope, and good yields.

Significance Recycling of reactive iodine from heterogeneous processes on sea-salt aerosol was hypothesized over two decades ago to play an important role in the atmospheric cleansing capacity. However, the understanding of this mechanism has been limited to laboratory studies and has not been confirmed in the atmosphere until now. We present atmospheric measurement of gas-phase iodine interhalogen species and show that their production via heterogeneous processing on marine aerosols is remarkably fast. These observations reveal that the atmospheric recycling of atomic iodine through photolysis of iodine interhalogen species is more efficient than previously thought, which is ultimately expected to lead to higher ozone loss and faster new particle formation in the marine environment., Reactive iodine plays a key role in determining the oxidation capacity, or cleansing capacity, of the atmosphere in addition to being implicated in the formation of new particles in the marine boundary layer. The postulation that heterogeneous cycling of reactive iodine on aerosols may significantly influence the lifetime of ozone in the troposphere not only remains poorly understood but also heretofore has never been observed or quantified in the field. Here, we report direct ambient observations of hypoiodous acid (HOI) and heterogeneous recycling of interhalogen product species (i.e., iodine monochloride [ICl] and iodine monobromide [IBr]) in a midlatitude coastal environment. Significant levels of ICl and IBr with mean daily maxima of 4.3 and 3.0 parts per trillion by volume (1-min average), respectively, have been observed throughout the campaign. We show that the heterogeneous reaction of HOI on marine aerosol and subsequent production of iodine interhalogens are much faster than previously thought. These results indicate that the fast formation of iodine interhalogens, together with their rapid photolysis, results in more efficient recycling of atomic iodine than currently considered in models. Photolysis of the observed ICl and IBr leads to a 32% increase in the daytime average of atomic iodine production rate, thereby enhancing the average daytime iodine-catalyzed ozone loss rate by 10 to 20%. Our findings provide direct field evidence that the autocatalytic mechanism of iodine release from marine aerosol is important in the atmosphere and can have significant impacts on atmospheric oxidation capacity.

Purified commercially available carbon nanotube (CNT) sheet and yarn materials were chemically doped in solutions of IBr using varying solvents to enhance the CNT bulk electrical conductivity. Time-dependent optical absorption spectroscopy was employed to quantify IBr adsorption onto the CNT samples, and results correlate dopant adsorption with CNT conductivity enhancement. Two independent solvent systems were evaluated (hexanes and ethanol) leading to 40% greater conductivity for CNTs doped with IBr in hexanes compared to CNTs doped with IBr in ethanol. A comparative analysis of IBr in nine solvents with varying polarities at 2.1 g of IBr per liter of solvent was employed to evaluate CNT doping efficacy and supports a mechanism whereby saturated solutions in hexanes and water favor dopant–CNT interactions that shift the equilibrium in favor of dopant adsorption and yield the highest CNT electrical conductivity. Saturated dopant solution loadings of 10–20 g IBr/L hexanes resulted in the maximum electrical...

Thermal reaction of phthalonitrile with hafnium powder under iodine monobromide (IBr) yields a new type molecule: bis(hafnium(IV) stapled phthalocyanine) derivative complex. X-ray single crystal analysis shows that the complex molecule consists of two hafnium phthalocyanine units bridged by the unique internal ligand that stapled by two carbon–carbon [Formula: see text] bonds to both HfPc-units. The internal dianionic ligand consists of two fragments, each of them present the three fourth part of phthalocyaninate ring. Both fragments are linked together through the bridging 1,2-di[amine(imine)methyl]benzene. The X-ray conformation of the bis(hafnium(IV) stapled phthalocyanine) derivative complex cation is confirmed by DFT calculations. An absence of the Q-band in the UV-vis spectrum, the typical band for the fully delocalized [Formula: see text]-electron aromatic phthalocyaninato(2-) ring system, indicates on drastic modification of the chromophore in this Hf-phthalocyanine complex that was confirmed by TD DFT calculations.

Iodonium ions have been developed for activating glycosyl bromides in the coupling to glycosyl acceptors. The iodonium ions are generated from N-iodosuccinimide and a protic acid such as camphorsulfonic acid or triflic acid, where the latter gives the most reactive promoter system. The couplings occur with the release of iodine monobromide, and the best results are obtained with benzoylated glycosyl donors and acceptors. In this way, disarmed glycosyl bromides can serve as glycosyl donors without the use of heavy-metal salts.

The electronic properties of carbon nanostructures such as carbon nanotubes (CNTs) or graphene can easily be tuned by the action of various doping agents. We present an experimental study and numerical analysis of how and why metallic and semiconductive CNTs can be p-doped by exposing them to two interhalogens: iodine monochloride and iodine monobromide. Simple application of these compounds was found to reduce the electrical resistance by as much as 2/3 without causing any unfavorable chemical modification, which could disrupt the highly conductive network of sp2 carbon atoms. To gain better insight into the underlying mechanism of the observed experimental results, we provide a first principles indication of how interhalogens interact with model metallic (5,5) and semiconductive (10,0) CNTs.

Herein, we present some aspects regarding the iodination/bromination of 4-hydroxycoumarin or its O-methyl or O-acetyl derivatives with iodine monochloride or iodine monobromide as halogenation reagents. Also, the investigation of photochemical transformation of the three 3-iodocoumarins was investigated for the first time.

Poly(amidoamine) dendrimers are very interesting macromolecules with highly branched structures and globular-shaped branched polymeric architectures. They are widely used for drug and gene delivery applications. In order to provide important insight into the interactions of poly(amidoamine) dendrimers with some organic acceptors, the binding of small molecules to 4-hexylamino-1,8-naphthalimide-labelled PAMAM dendrimer (PD) have been studied by spectrophotomeric method. The acceptors used in this research include chloranilic acid (CLA), p-chloranil (CHL), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), 7,7ʹ,8,8ʹ-tetracyanoquinodimethane (TCNQ), picric acid (PA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and iodine monobromide (IBr). The spectrophotometric measurements proved that all the charge-transfer (CT) complexes are formed via a stoichiometry (PD: acceptor) of 1:2 (except for IBr acceptor). Accordingly the obtained complexes could be formulated as [(PD)(CLA)2], ...

Iodine monobromide (IBr) and its cation (IBr+), which play an important role in the stratospheric ozone depletion, have received much attention. However, the electronic states of IBr/IBr+ have not been well understood. In this paper, the potential energy curves (PECs) of low-lying electronic states for IBr/IBr+ were computed with high-level multireference configuration interaction (MRCI) method. The spin–orbit coupling effect was taken into account via the state interaction method with the full Breit–Pauli Hamiltonian. For IBr, the PECs of 12 Λ–S states correlated with the lowest dissociation limit of IBr molecule and 23Ω states generated from those Λ–S states were calculated. The spectroscopic constants of the bound states were obtained, which are consistent with previous experimental results. The two avoided crossing points between (2)0+/(3)0+ and (3)0+/(4)0+ were interpreted by analysis of Λ–S compositions of Ω states at various bond lengths. Based on potential energy curves and transition dipole moments, the radiative lifetime of 13Π1 was evaluated. For IBr+, the PECs of 12 Λ–S states and 4 low-lying Ω states were calculated, from which the spectroscopic constants were evaluated. Finally, the ionization energies from the neutral ground state (X1Σ+) to different ionic states (X2Π3/2, X2Π1/2, A2Π3/2 and A2Π1/2) were obtained.

Chemical Physics As light pulses get shorter in time, they correspondingly get broader in frequency. Kobayashi et al. take advantage of both properties of attosecond pulses to elucidate iodine monobromide (IBr) photodissociation by detecting ultrafast bromine and iodine spectral shifts simultaneously. A preliminary burst of light weakens the I–Br bond. Then, as the atoms fly apart, they reach a configuration where the bond vibration can couple ground and excited electronic states. The broadband probe pulse reveals rapid changes in each atom's electronic structure at this juncture. Science , this issue p. [79][1] [1]: /lookup/doi/10.1126/science.aax0076

Iodonium ions have been developed for activating glycosyl bromides in the coupling to glycosyl acceptors. The iodonium ions are generated from N-iodosuccinimide and a protic acid such as camphorsulfonic acid or triflic acid, where the latter gives the most reactive promoter system. The couplings occur with the release of iodine monobromide, and the best results are obtained with benzoylated glycosyl donors and acceptors. In this way, disarmed glycosyl bromides can serve as glycosyl donors without the use of heavy-metal salts.

The interaction of halogen molecules of varying electron affinity, such as iodine monochloride (ICl), bromine (Br2), iodine monobromide (IBr) and iodine (I2) with single-walled carbon nanotubes (SWNTs) and graphene has been investigated in detail. Halogen doping of the two nanocarbons has been examined using Raman spectroscopy in conjunction with electronic absorption spectroscopy and extensive theoretical calculations. The halogen molecules, being electron withdrawing in nature, induce distinct changes in the electronic states of both the SWNTs and graphene, which manifests with a change in the spectroscopic signatures. Stiffening of the Raman G-bands of the nanocarbons upon treatment with the different halogen molecules and the emergence of new bands in the electronic absorption spectra, both point to the fact that the halogen molecules are involved in molecular charge-transfer with the nanocarbons. The experimental findings have been explained through density functional theory (DFT) calculations, which suggest that the extent of charge-transfer depends on the electron affinities of the different halogens, which determines the overall spectroscopic properties. The magnitude of the molecular charge-transfer between the halogens and the nanocarbons generally varies in the order ICl > Br2 > IBr > I2, which is consistent with the expected order of electron affinities.

Interhalide ion formation resulting from the freezing of dilute solutions containing components found in natural sea salt are investigated as a potential mechanism for the release of interhalogens to the polar atmosphere. Acidified solutions containing iodide, bromide, and nitrite ions have been frozen and then thawed, with changes in speciation analyzed using UV-visible spectrophotometry. The freezing process is shown to induce the formation of the important interhalide ion, IBr(2)(-). This species has previously been predicted to be a precursor of iodine monobromide, IBr, and represents a potentially important source of halogen atoms in the polar marine boundary layer. The reaction mechanisms that lead to the formation of IBr(2)(-) under freezing conditions are explored using both experimental and computational methodologies. The chemistry involved was subsequently modified in order to mimic naturally occurring conditions more closely and also incorporated the use of hydrogen peroxide as an oxidant. In contrast to previous studies, the freeze-induced production of IBr(2)(-) was thereby observed to occur up to pH5.1, where the acidity levels are comparable to those found in the polar snowpack.

Dissociation dynamics of iodine monobromide has been theoretically investigated at numerous excitation wavelengths in the visible wavelength region (450–540 nm) by an accurate time-dependent dynamical simulation technique. The interatomic potential energy curves are derived from ab initio methods which are then employed in a Landau–Zener treatment to calculate the spin-orbit branching ratios in the two halogen products. The extinction coefficients, in arbitrary units, for the discrete electron transition are obtained through a numerical algorithm. Based on these elastic scattering calculations, the results of Br*: Br branching ratios are determined at several simulation wavelengths. Also the electronic properties are evaluated to elucidate the mechanism of chemical dynamics of the system. It is found that the branching dynamics can be clarified via the Landau–Zener model, which treats an avoided crossing between two states of a given nature and evaluates a nonadiabatic effect relevant to the dissociation of IBr molecule.

Summary Of the methods available for ascorbic acid assay the one normally recommended is based on its reduction of the blue dye 2,6-dichlorophenolindophenol to give a colourless product (Nicholls, 1945; Pearson, 1962). Another procedure depends on the reduction of iodine generated by the action of standard iodate on excess iodide in 0.25 M sulphuric acid (Nicholls, 1945; Ballentine, 1941). Iodine monobromide prepared by mixing equimolar quantities of iodine and bromine in hydrobromic acid has also been employed to determine ascorbic acid among other compounds (Nazrullaev, Gengrinovich & Murtazaev, 1963).

The silanol (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH has been shown to isomerize to (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) when it was kept at room temperature for 10 h in 0.2 M NaOMe/MeOH. Corresponding isomerizations of the above silanol (to give (Me 3 Si) 2 CHSi(C 6 H 4 Me- p ) (Me)(OSiMe 3 )) are complete after 26 h under reflux in pyridine. The reaction involve 1,3-migration from carbon to oxygen within a silanolate ion to give a carbanion, which rapidly acquires a proton from the solvent. Treatment of (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH with MeLi in Et 2 O/THF give, by the same rearrangement, the organolithium reagent (Me 3 Si) 2 CLiSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) which on treatment with Me 2 SiHCl gives (Me 3 Si) 2 C(SiMe 2 H)Si(C 6 H 4 Me- p )(Me)(OSiMe 3 ) and (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). When the experiment was repeated, but with Me 3 SiCl in place of Me 2 SiHCl, it gives exclusively (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). Treatment of the organolithium reagent (Me...

The synthesis, X-ray structure [monoclinic, P21/n, a = 12.1690(1), b = 7.8360(1), c = 14.4250(1) A, β = 113.808(2)°], spectroscopic and electrochemical characterization of a new powerful reagent based on the iodine monobromide adduct of the N,N′-dimethylperhydrodiazepine-2,3-dithione (Me2dazdt) ligand, able to oxidize gold metal in a one-step reaction under mild conditions, is reported. The gold metal dissolution has been performed on gold powder, wires and Au/Ti thin layers. The oxidation product has been isolated and structurally characterised as [Au(Me2dazdt)Br2]IBr2 [monoclinic, C2/c, a = 26.523(8), b = 10.191(6), c = 14.549(7) A, β = 111.57(2)°]. The metal is essentially within a square planar geometry, Me2dazdt acts as an S,S chelating ligand and two bromide ligands complete the geometry around the metal. The IBr2− counteranion is essentially linear and shows I–Br bond lengths slightly asymmetric [Br(4)–I(1) 2.742(3), Br(3)–I(1) 2.682(2) A]. A comparison with the gold removal from Si/SiO2/Au/Ti thin layers of comparable thickness to that found in microelectronic devices, by using THF solutions of IBr and I2 adducts of the Me2dazdt donor, as well as the currently used I2/I− aqueous solutions, shows that these dihalogens-adducts produce a quantitative gold removal in shorter times and leaving the underlying layer perfectly clean, and are thus highly desirable as new etching agents in the gold-based technology of semiconductor devices.

USP/NF 2000 [The United States Pharmacopeia, Rockville USA, 24th ed., 2000, p. 1868, The National Formulary, 19th ed. 2000] and PH. EUR. 1997 [European Pharmacopoeia, third ed., Council of Europe, Strasbourg, 1997, pp. 63–64] determine the iodine values according to Hanus with iodine monobromide in glacial acetic acid. This reagent can be replaced by a solution of 1,3-dibromo-5,5-dimethylhydantoin (DBH) and potassium iodide or iodine in the same solvent. Both reagents yield equivalent results by means of method comparison according to Passing and Bablok [J. Clin. Chem. Clin. Biochem. 21 (1983) 709; 22, (1984) 431] in relation to the official method of PH. EUR.

Tetraphenylphosphonium triiodotetrabromide [PPh4][I3Br4] is obtained by the reaction of tetraphenylphosphonium bromide with iodine monobromide. It is the first example of an iodine rich, seven-membered polybromide. [PPh4][I3Br4] crystallizes triclinic in the space group P1 with a = 10.947(1) A, b = 11.945(1) A, c = 12.896(1) A, alpha = 66.80(1) degrees, beta = 77.21(1) degrees, gamma = 85.73(1) degrees, and two formula units per unit cell. The final R indices [I4 sigma(I)] are R1 = 0.0362 and wR2 = 0.0944.

A high-resolution (1–11 meV) threshold photoelectron spectroscopic study of ICl has been performed using synchrotron radiation and a penetrating-field electron spectrometer over the valence ionization region of the molecule. Accurate vibrational constants have been obtained for both spin–orbit components of the ICl+ (X 2 Π i ) state through the observation of extended vibrational bands in the Franck–Condon gap regions of the molecular ion. The appearance of these vibrational bands is attributed to resonant autoionization of Rydberg states residing in this energy region of the ionic state. The adiabatic (v+=0) ionization potentials for formation of the ground state of the ICl+ ion are found to be 10.076±0.002 eV for (X 2 Π 3/2 ) and 10.655±0.002 eV for (X 2 Π 1/2 ) yielding a spin–orbit splitting in this state of 0.579±0.002 eV. The adiabatic (v+=0) ionization potential for formation of the (A 2 Π i ) state of ICl+ is estimated to be at ∼12.5 eV. Additional autoionization effects are noted in the formation of the (A 2 Π i ) and (B 2 Σ + ) band systems in ICl+.

c-axis thermoelectric power (TEP) S c of stage-2 graphite intercalation compound with iodine monobromide (IBr-GIC) was measured below the room temperature, and the calculation was carried out by our theory. The major part of S c comes from the diffusion TEP S c-d. However, a slight deviation exists between S c-d and the experimental result S c and it can be removed in consideration of phonon drag TEP S c-p. This situation was different from the case of graphite intercalation compound with iodine monochrolide (ICI-GICs). Above the room temperature, we attempted to measure the TEP of stage-2 IBr-GIC. It shows the phase transition similar to the case in ICI-GICs.

Treatment of ‘armed’ methyl thiogalactosides with iodine in the absence of an acceptor alcohol results in thioglycoside epimerisation, whereas there is no effect on the corresponding ‘disarmed’ methyl thioglycosides. In contrast, iodine–hexamethyldisilane (which generates iodotrimethylsilane in situ) brings about epimerisation of ‘disarmed’ thioglycosides, ultimately giving rise to the corresponding α-glycosyl iodides on extended exposure. Cross-over experiments show the former iodine-promoted epimerisation process to be intermolecular, whereas the latter iodine–hexamethyldisilane-promoted epimerisation is intramolecular. Treatment of the same methyl thiogalactosides with iodine monobromide gives rise to the thermodynamically favoured α-glycosyl bromides, whereas reaction with iodine monochloride initially gives the kinetic β-glycosyl chlorides, which slowly epimerise to the thermodynamic α-linked products. Differences in the outcome of thioglycoside activation by I–I, I–Br and I–Cl suggest there may be scope for influencing the stereochemical course of thioglycoside-based glycosylation reactions through careful choice of promoter.

The reactions of the thioamides thiourea, tu, 1-ethyl-2-thiourea, etu, 1,3-dimethyl-2-thiourea, dmtu, 1,3-diethyl-2-thiourea, detu, 3-methylbenzothiazole-2-thione, mbtt and 3-methylrhodanine, mrh, with one equivalent of diiodine have been studied; attempts have been made to characterise the resultant 1∶1 addition products using FT-Raman spectroscopy. It has been shown that these materials lie on a CT–ionic borderline. The crystal structure of dmtu·I2 has been determined and is shown to be ionic and of the form [(dmtu)2I]+I3−, an arrangement previously only rarely found in crystallographic reports. The reactions of etu and dmtu with iodine monobromide and iodine monochloride and of mbtt with iodine monobromide give 1∶1 interhalogen addition products; initial FT-Raman investigations point to these adopting a CT ‘spoke’ structure. The reaction of tu with two equivalents of diiodine to give a bulk material of stoichiometry tu·I4 has been studied in detail and shown to lead to a variety of novel polyiodide arrangements, the crystal structures of two of which are reported, (tu)2(I2)3 and (tu)3(I2)5, and compared to each other, the previously reported (tu)2I2 and to tu itself. These two structures represent further, previously unreported, structural motifs available for these highly complicated systems.

Iodine monobromide in dichloromethane―methanol or acetonitrile constitutes an effective reagent for the deprotection of O-trityl and O-dimethoxytrityl ethers of carbohydrates and nucleosides. Acid-labile functionalities (acetals, O-p-methoxybenzyl ethers, etc.) as well as base-labile groups (esters and amides) are stable under these conditions; and the method has been found to be superior to the hitherto known literature methods.

c -axis thermoelectric power (TEP) of stage-2 IBr-GIC exhibits a linear temperature dependence at low temperature, which ascribed to the diffusion term. Around 80 K its slop becomes gently. This im...

The synthesis of the new halogenated alcohol BrCF 2 CFClCH 2 CHICH 2 OH as a precursor of 4,5,5 trifluoro-4-ene pentanol F 2 CCFC 3 H 6 OH is based on a two-step process. First, the radical addition of iodine monobromide to chlorotrifluoroethylene (CTFE) led to the expected BrCF 2 CFClI (I) and ICF 2 CFClBr (II), but also to BrCF 2 CFClBr (III) and ICF 2 CFClI (IV), the amount of which determined by 19 F NMR depended on the reaction conditions: by feeding CTFE into IBr continuously or in batches; photochemical or thermal initiations, and with various initial [IBr] 0 /[CTFE] 0 molar ratios. In most cases, isomer (I) was mainly produced. The second step concerned the addition of such a mixture to allyl alcohol yielding the polyhalogenoalcohol with a quantitative conversion of (I). The reactivity of different halogeno end-groups of these isomers toward the allyl alcohol was discussed. Reduction of the iodine atom into hydrogen and the halogenated alcohol was accompanied by that of the bromine atom leading to BrCF 2 CFClC 3 H 6 OH and HCF 2 CFClC 3 H 6 OH (V). Dehalogenation of the former alcohol in the presence of zinc led to F 2 CCFC 3 H 6 OH while dehydrochlorination of (V) into trifluorovinyl hydroxy monomers was achieved in the presence of potassium hydroxide but in poor yields. Strategies starting from the radical additions of iodine monochloride and of iodine monobromide were compared showing that the former led to better overall yields of trifluorovinyl alcohol than the latter.

Two 1∶1 interhalogen adducts of N-methylbenzothiazole-2-selone (mbts) have been prepared and crystallographically characterised: mbts·IBr (1) and mbts·ICl (2). Both exhibit the charge transfer ‘spoke’ structure consisting of a linear Se–I–X arrangement (X = Br or Cl) where d(C–Se) increases from that seen for mbts by 0.058(5) and 0.062(8) A (1 and 2 respectively); d(C–N) decreases by 0.019(4) and 0.019(9) A. This indicates electron density moves towards the Se–I–X moiety upon co-ordination, causing a partial positive charge to reside on the nitrogen atom. The I–X bond lengthens with respect to the unco-ordinated species for both molecules. The addition of two equivalents of ICl to mbts gave a dark purple material of stoichiometry C8H7Cl2.9I1.1NSSe 3; the fractional stoichiometry for iodine and chlorine may be indicative of ‘halogen scrambling’. An additional product from this reaction was examined crystallographically and found to consist of the ion pair [C8H7NSCl]+[ICl2]–4, i.e. the C–Se double bond has been completely cleaved and replaced by a C–Cl single bond. The positive charge is again supported mostly by the nitrogen atom; d(C–N) decreases to 1.294(10) A indicating a double bond.

Reaction of 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione 1 with diiodine or iodine monobromide in CH2Cl2 resulted in the formation of molecular charge-transfer complexes 1·I2 and 1·IBr respectively. Both complexes have been characterised crystallographically and contain a linear S–I–X (X = I or Br) moiety with the sulfur adopting a tetrahedral geometry taking into account the stereochemically active lone pairs. The S–I [2.716(3)] and I–I [2.808(3) A] bond lengths in 1·I2 are similar to those reported for diiodine complexes of related thione donors. The adduct 1·IBr is the first crystallographically characterised thione–iodine monobromide charge-transfer complex. The S–I distance [2.589(2) A] is shorter than that in 1·I2, consistent with IBr being a stronger acceptor than I2. The I–Br distance [2.7138(11) A] is lengthened with respect to that in unco-ordinated IBr, but within bonding distance when compared to the sum of the van der Waals radii for iodine and bromine (3.75 A). Treatment of 1 with dibromine under identical conditions resulted in the formation of the adduct 1·Br2 and the dithiolylium salt [C5H6S4Br][Br3]·½Br2 2. Treatment of 1 with Br2 in toluene led to the isolation of 1·Br2 only. The crystal structure of 1·Br2 shows the compound to contain a linear Br–S–Br moiety with the sulfur in a T-shaped or Ψ-trigonal bipyramidal environment (taking into account the stereochemically active lone pairs). The structure of 2 reveals a three component system consisting of the [C5H6S4Br]+ cation, the [Br3]– anion and a molecule of Br2 in a 2∶2∶1 ratio. These components are held in the lattice by a series of weak intermolecular interactions which link the tribromide ions and dibromine molecules into zigzag chains.

We present the high resolution two-photon one-colour photoelectron (ZEKE-PFI) spectrum of IBr excited via a repulsive intermediate state. Both spin–orbit components ( X 2 Π 3/2 and X 2 Π 1/2 ) of the ground electronic state have been observed. The adiabatic ionisation energies have been determined to be 79 018±1 cm −1 for the X 2 π 3/2 state and 83 680±1 cm −1 for the X 2 Π 1/2 state, giving a spin–orbit splitting of 4662±2 cm −1 . An extended progression allowed resolution of the vibrational isotope shift and vibrational constants have been determined for both isotopomers (I 79 Br and I 81 Br) in the X 2 Π 3/2 state: ω e =303±1 cm −1 and ω e x e =1.0±0.1 cm −1 for I 79 Br + and ω e =300±1 cm −1 and ω e x e =0.9±1 cm −1 for I 8 1 BR + . The vibrational progression in the ( X 2 Π 1/2 ) state extended only as far as v + =3 and, as a result, the isotope shift was not resolved. The vibrational constants for the upper spin–orbit component were determined as ω e =300±1 cm −1 and ω e x e =2.0±0.2 cm −1 . The role of repulsive intermediate states, at the one photon level, in the formation of extended vibrational progressions, is discussed.

The adsorption of monoenergetic IBr molecules on the Si(111)-7×7 surface has been studied using scanning tunneling microscopy, mass spectrometry, Auger electron spectroscopy, and supersonic molecular beam techniques. The adsorption proceeds predominantly via the direct abstractive adsorption mechanism and preferentially occurs at the center Si adatoms. The IBr abstraction probabilities at the incident energies of 0.15 and 0.82 eV have been determined to be 0.90±0.03 and 0.77±0.03, respectively. The minor dissociative adsorption channel of IBr can be enhanced at the expense of the abstractive adsorption channels by raising the incident energy. Most importantly, no atomic selectivity for iodine or bromine was observed. A reaction mechanism involving two types of transition states, Si⋯I⋯Br(s) and Si⋯Br⋯I(s), has been proposed to interpret the experimental observations. The attractive interaction between the nearly symmetric highest occupied molecular orbitals (HOMO, π* antibond) of IBr and the partially-fill...

The half-thickness and mass absorption coefficient of 13.0 keV x-rays, 46.5 keV γ-rays, and 1.16 MeV βƟ particles have been measured for pristine, bromine intercalated, and iodine monobromide intercalated pitch-based graphite fiber composites. Since these materials have been proposed to replace aluminum structures in spacecraft, the results were compared to aluminum. Pristine graphite epoxy composites were found to have about 4.0 times the half-thickness, and 40% of the mass absorption of aluminum for ionizing radiation. Bromine intercalation improved performance to 90% of the half-thickness, and 1.7 times the mass absorption coefficient of aluminum. Iodine monobromide extended the performance to 70% of the half-thickness and 3.0 times the mass absorption of aluminum. Thus, intercalation not only makes up the deficiency conventional composites have in shielding components from ionizing radiation, but actually confers advantages in mass and thickness over aluminum. The βƟ particle shielding of all the materials tested was found to be very effective. The shielding of all of the materials was found to have nearly the same mass absorption coefficient of 17.8 ± 0.9 cm2/g. Inelastic scattering processes were found to be important in βƟ particle shielding; however, the extent of inelastic scattering and thus the distribution of energies of the transmitted electrons did not vary with material.

laser operating on the 1001-1000 transition at λ=4.3 μm and pumped by E –V energy transfer from Br(2P1/2) has been demonstrated. The dynamics and performance of this device were characterized by observing the time-resolved stimulated emission and the steady-state spontaneous side fluorescence after photolysis of IBr or Br2 by a frequency-doubled Nd:YAG laser or Ar+ laser, respectively. Although the E –V excitation kinetics are favorable, rapid vibrational relaxation limits laser action to CO2 pressures of less than 1 Torr. Numerical modeling of laser pulse shapes and the dependence on IBr and CO2 pressure and photolysis energy establish a relatively high gain of 0.33%/cm, a CO2-pressure-dependent optical loss of 0.04–0.06%/cm, and an efficiency of 2×10-5 4.3-μm-laser photons per incident photolysis photon. The CO2 fluorescence after photolysis of a fixed Br2/CO2 gas mixture decreases as a function of photolysis time by about 30%/h, indicating the photolytic production of an important quencher.

Iodine monobromide has been found to be an efficient reagent for the conversion of both ‘armed’ and ‘disarmed’ thioglycosides (SMe, SPr i , SPh) into glycosyl bromides. This reagent is compatible with most common protecting groups, and O -glycosidic linkages. The additional potency of IBr, compared to iodine, as an iodonium ion source also permits the glycosylation of sugar alcohols by ‘disarmed’ glycosyl bromides and thioglycosides.

P1/2 – 42P3/2 transition at λ=2.71 μm and pumped by photolysis of IBr with a frequency-doubled Nd:YAG laser has been demonstrated. The dynamics and performance of this device were characterized by observing the temporal dependence of the stimulated emission for various laser photolysis energies (20–125 mJ/pulse) and IBr pressures (0.7–6.7 torr). The gain is directly proportional to the number of absorbed photolysis photons, with a value of 0.9 %/cm over 41 cm at an IBr pressure of 5 torr. The inversion is quenched rather slowly, with a pulse duration of greater than 2 μs, after short-pulse (10 ns) excitation. The laser energy is maximized at 2.5 torr of iodine monobromide in a photolysis cell of 90 cm. A numerical solution to the rate equations for the laser pulse shapes provides a threshold inversion of Δth=2.9×1013 atoms/cm3. The energy efficiency of this device is limited principally by the low quantum efficiency, poorly matched pump and cavity mode volumes, and the photolysis yield of a single isotope hyperfine component of Br(2P1/2). A nitric oxide, NO(v=2→v=1), laser at λ=5.4 μm pumped by electronic-to-vibrational energy transfer from the photolytically produced Br(2P1/2) has also been demonstrated. The output energy and gain of this NO laser is adversely affected by rapid V-V relaxation.

The reaction of R2Se (R = Ph or Me) with iodine monobromide in diethyl ether solution produced the charge-transfer complexes R2SeI–Br. In the case of Ph2Se, Ph2SeIBr was produced quantitatively. However, for Me2Se, both Me2SeIBr and the ionic product [Me3Se][IBr2] were produced indicating ease of methyl migration for Me2SeIBr and that it lies close to the ionic/covalent structural borderline. The other product from this autoionisation is believed to be Me2Se2I2, although this was not extensively characterised. The compounds Ph2SeIBr and Me2SeIBr show markedly different d(I–Br) 2.640(2) and 2.797(5) A, respectively, illustrating how the R groups on the selenium affect its donor power towards iodine monobromide. The three compounds Ph2SeIBr, Me2SeIBr and [Me3Se][IBr2] have been characterised by single-crystal X-ray diffraction.

Microwave irradiation accelerates the bromination of 1, 4-quinones and coumarins with (i) bromine adsorbed on neutral alumina in “dry media” and (ii) with iodine monobromide in acetic acid as compared to the reactions run at room temperature. Bromination takes place selectively at active quinonoid position in 1,4-quinones and at α, β-double bond in coumarins.

It was found by 13 C-NMR that the doping of iodine monobromide (IBr) into C 60 solid changes significantly the electronic states of C 60 , indicating chemical reaction between C 60 and halogen atoms, such as charge transfer and bonding. On the other hand, no significant change in 13 C-NMR characteristics was observed in C 60 solids doped by iodine (I 2 ) and iodine tricloride (ICl 3 ). A possibility of metallic states at C 60 sites was suggested by spin-lattice relaxation time measurement in IBr-doped C 60 .

Sticking point in the formation of the 1,3-thiazeto[3,2-a]quinoline skeleton is a cyclization step using the system vicinal dihaloalkane / potassium iodide as a controlled source of iodine monobromide which halogenates the carbon α to the thiol.

La famille des composés halogènes et inter-halogènes représentent des solides moléculaires adoptant des phases denses communes avec des solides moléculaires diatomiques comme l’azote et l’hydrogène. Parmi les transformations structurales et électroniques induites sous haute pression et observées dans ces solides, on note, entre autres, la dissociation moléculaire et la métallisation. De plus, l’étude des phases denses de l’iode a permis récemment l’observation d’une structure cristalline possédant une modulation dite incommensurable, c’est-à-dire une modulation possédant une périodicité différente de celle de la structure cristalline, jetant ainsi une lumière nouvelle sur le processus de dissociation moléculaire dans les solides halogènes. Dans ce mémoire, on propose d’étudier les changements structuraux dans monobromure d’iode (IBr), un composé inter-halogène possédant des propriétés structurales semblables à celles de deux composés halogènes, soit l’iode (I2) et le brome (Br2) sous leur forme solide. Des expériences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont été réalisées à température ambiante sur l’IBr en variant la pression jusqu’aux environs de 60 GPa. La nature chimique particulière du composé IBr a nécessité la mise au point de techniques de chargement d’échantillon destinées à préserver l’intégrité chimique de la substance utilisée. On rapporte également l’observation d’une phase de l’IBr présentant une modulation incommensurable. Les phases observées dans l’IBr permettent d’établir des parallèles avec les phases denses rapportées dans I2 et Br2 par le biais d’un modèle phénoménologique décrivant la séquence structurale des solides halogènes sous forme condensée.

The iodine value (iodine number) is an important analytical characteristic of fats and oils. Leading pharmacopeias determine it using iodine monobromide (Hanus method). We used methyl oleate as a simple analog of unsaturated triacylglycerols to identify the products. After performing the reaction in deuterated solvents under pharmacopeial conditions, NMR spectroscopy revealed the presence of the 9, 10-diiodo, 9, 10-dibromo, and 9, 10-bromoiodo adducts, leaving no educt olefin. The prescribed subsequent addition of potassium iodide led to the formation of methyl 9, 10-diiodo and bromoiodo stearate in equal amounts.

Iodine monobromide affords superior distereoselectivity in low-temperature electrophilic cyclizations of homoallylic carbonates. Solvent and temperature effects and the scope and limitations of the method are discussed; optimal selectivity is obtained in toluene at -80 to -85 o C. The latter protocol generally furnishes significantly enhanced selectivity, vis-a-vis the original procedure employing I 2 in acetonitrile at -20 o C; for example, the IBr-induced cyclization of 14 affords a 25.8:1 mixture of 15 and 16, whereas I 2 gives an 8.4:1 ratio. An equilibration experiment established that the diastereoselectivity derives primarily or exclusively from kinetic control of the cyclization process

The high-resolution infrared spectrum of iodine monobromide was recorded in absorption by Fourier transform spectroscopy. About 400 rovibrational transitions were observed near 260 cm −1 . The lines were assigned to the v = 1 ← 0 and v = 2 ← 1 bands of the X 1 Σ + electronic state of I 79 Br and I 81 Br. The infrared data were combined with millimeter-wave data from the literature to give improved molecular constants.