New members of an old family: isolation of IC(O)Cl and IC(O)Br and evidence for the formation of weakly bound Br*...CO

The photochemically induced reactions of a dihalogen, XY, with CO isolated together in an Ar matrix at about 15 K lead to the formation of carbonyl dihalide molecules XC(O)Y, where X and Y may be the same or different halogen atoms, Cl, Br, or I. In addition to the known compounds OCCl2, OCBr2, and BrC(O)Cl, the carbonyl iodide chloride, IC(O)Cl, and carbonyl iodide bromide, IC(O)Br, compounds have thus been identified for the first time as products of the reactions involving ICl and IBr, respectively. The first product to be formed in reactions with Cl2, BrCl, or ICl is the ClCO* radical, which reacts subsequently with a second halogen atom to give the corresponding carbonyl dihalide [OCCl2, BrC(O)Cl, or IC(O)Cl]. The analogous reaction with Br2 affords, in low yield, the unusually weakly bound BrCO* radical, better described as a van der Waals complex, Br*...CO. The changes have been followed and the products characterized experimentally by their infrared spectra, and the spectra have been analyzed in light of the results afforded by ab initio (Hartree-Fock and Moeller-Plesset second-order) and density functional theory calculations.     

Formation of new halogenothiocarbonylsulfenyl halides, XC(S)SY, through photochemical matrix reactions starting from CS2 and a dihalogen molecule XY (XY=Cl2, Br2, or BrCl)

Isolation of a dihalogen molecule XY (XY=Cl2, Br2, or BrCl) with CS2 in a solid Ar matrix at about 15 K leads, by broad-band UV-vis photolysis (200相似文献   

Matrix photochemistry of syn-(chlorocarbonyl)sulfenyl bromide, syn-ClC(O)SBr: precursor to the novel species anti-ClC(O)SBr, syn-BrC(O)SCl, and BrSCl

The vapor of (chlorocarbonyl)sulfenyl bromide, ClC(O)SBr, was isolated in solid Ar, Kr, N(2), and Ar doped with 5% CO at 15 K, and the matrix was subsequently irradiated with broad-band UV--visible light (200 < or = lambda < or = 800 nm), the changes being followed by reference to the IR spectrum of the matrix. The initial spectrum showed the vapor of ClC(O)SBr to consist of more than 99% of the syn form (with the C==O bond syn with respect to the S--Br bond) in equilibrium with less than 1% of the anti conformer. Irradiation caused various changes to occur. First, conformational randomization took place, leading to a roughly equimolar mixture of the two rotamers, and so affording the first spectroscopic characterization of an anti-ClC(O)S-containing compound. Simultaneously, the novel constitutional isomer syn-BrC(O)SCl was also formed. Continued photolysis resulted in the decay of all these species while revealing a third reaction channel, leading to the elimination of CO and the formation of the new triatomic sulfur halide BrSCl. The assignment of the IR bands to the different products was made on the basis of the usual criteria, taking account (i) of the effects of the naturally occurring isotopic pairs (35)Cl/(37)Cl and (79)Br/(81)Br, (ii) of the vibrational properties of related molecules, and (iii) of the properties predicted for the relevant molecules by quantum chemical calculations.     

Heterogeneous reactions of HOI, ICl and IBr on sea salt and sea salt proxies

The heterogeneous chemistry of HOI, ICl and IBr on sea salt and sea salt proxies has been studied at 274 K using two experimental approaches: a wetted wall flow tube coupled to an electron impact mass spectrometer (WWFT-MS) and an aerosol flow tube (AFT) coupled to a differential mobility analyser (DMA) and a chemical ionisation mass spectrometer (CIMS). Uptake of all three title molecules into bulk aqueous halide salt films was rapid and controlled by gas phase diffusion. Uptake of HOI gave rise to gas-phase ICl and IBr, with the latter being the predominant product whenever Br(-) was present. Only partial release of IBr was observed due to high solubility of dihalogens in the film. ICl uptake gave the same yield of IBr as HOI uptake. Uptake of ICl on NaBr aerosol was accommodation limited with alpha = 0.018 +/- 0.004 and gas phase IBr product has a yield of 0.6 +/- 0.3. The results show that HOI can act as a catalyst for activation of bromine from sea-salt aerosols in the marine boundary layer, via the reactions: HOI(aq) + Cl + H--> ICl(aq) + H(2)O(l) and ICl(aq) + Br--> IBr(aq) + Cl.     

31P CP-MAS NMR,Vibrational, and X-Ray Characterization of the Adducts of Triphenylphosphine Sulfide with ICl and IBr

The reactions between triphenylphosphine sulfide (Ph₃PS) and ICl in CCl₄ and IBr in CH₂Cl₂ in 1 : 1 molar ratio give the solid adducts Ph₃PS · ICl ( I ) and Ph₃PS · IBr ( II ) whose structures have been solved by X-ray diffraction. Compounds I and II consist of discrete molecule units and feature the S–I–Cl or S–I–Br linear group. The S–I bond distances in I , II (2.641(1), 2.665(1) Å respectively) and in compound 2 Ph₃PS · 3 I₂ ( III ) (2.729(2) Å) are correlable to the net increase in the I–X (X = Cl, Br, I) bond distance. The structural features of I , II and III are in accordance with ³¹P CP–MAS NMR, FT-Raman and FT-IR spectral data, and elucidate the nature of the donor (Ph₃PS)-acceptor (ICl, IBr, I₂) interaction.     

Reaction of Ba with ICl and IBr

The chemiluminescence from the reactions of Ba with ICl and IBr have been studied. Emission could be observed only from BaCl and BaBr. A broad emission in the near-IR could not be unambiguously assigned. The formation of IX-Ar (X = Cl, Br) van der Waals complexes quenched the chemiluminescence channel.     

Insights into the photochemical processes of ClC(O)SCl from ab initio calculations

All possible unimolecular processes upon photolysis of ClC(O)SCl in the UV-visible region have been characterized in the present paper through the optimized stationary structures and computed potential-energy profiles of the S0, S1, T2, and S2 states with the MP2, B3LYP, CASSCF, and MR-CI methods in conjugation with the cc-pVDZ basis set. Upon photoexcitation in the range of 300-400 nm, the ClC(O)SCl molecules are excited to the S1 state. From this state, the dissociation into ClC(O)S + Cl takes place immediately and subsequently Cl2 and SCO are formed. The C-Cl and C-S bond fissions that start from the S2 state are the dominant channels upon photodecomposition of ClC(O)SCl in the gas and condensed phases in the wavelength range of 200-248 nm. The formed Cl, C(O)SCl, ClCO, and SCl radicals are very reactive, and the Cl2, SCO, CO, and SCl2 molecules are subsequently produced as stable products in the condensed phase.     

Observation of adducts in the reaction of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) using cavity ring-down spectroscopy

The reactions of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) have been studied using cavity ring-down spectroscopy in 25-125 Torr total pressure of N2 diluent at 250 K. Formation of the XCH2I-Cl adduct is the dominant channel in all reactions. The visible absorption spectrum of the XCH2I-Cl adduct was recorded at 405-632 nm. Absorption cross-sections at 435 nm are as follows (in units of 10(-18) cm2 molecule(-1)): 12 for CH3I, 21 for CH3CH2I, 3.7 for CH2ICl, 7.1 for CH2IBr, and 3.7 for CH2I2. Rate constants for the reaction of Cl with CH3I were determined from rise profiles of the CH3I-Cl adduct. k(Cl + CH3I) increases from (0.4 +/- 0.1) x 10(-11) at 25 Torr to (2.0 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1) at 125 Torr of N2 diluent. There is no discernible reaction of the CH3I-Cl adduct with 5-10 Torr of O2. Evidence for the formation of an adduct following the reaction of Cl atoms with CF3I and CH3Br was sought but not found. Absorption attributable to the formation of the XCH2I-Cl adduct following the reaction of Cl atoms with XCH2I (X = H, CH3, Br, I) was measured as a function of temperature over the range 250-320 K.     

硫原子上亲核取代反应的密度泛函理论研究

在B3LYP/6-311 G(2df,p)的水平上,对反应X- CH3SCl(X=F,Cl,Br,I)进行了理论研究.计算结果表明:X-(X=Cl,Br,I)与CH3SCl作用时,实际发生的是在硫原子上而不是在碳原子上的亲核取代反应,而且属于加成-消去机理.但是F-与CH3SCl作用则容易发生脱质子反应.     

Matrix-isolated van der Waals complexes formed between CS2 and dihalogen molecules XY, Where XY = Cl2, Br2, BrCl, ICl, or IBr

Weakly bound 1:1 complexes formed between CS2 and a dihalogen molecule XY = Cl2, Br2, BrCl, ICl, or IBr have each been trapped in an Ar matrix and hence investigated experimentally by their IR spectra as well as theoretically by MP2 and density functional calculations. A planar structure, with an intermolecular angle close to 90 degrees , is expected for such a S=C=S...XY molecular complex. Moreover, for each system involving a heteronuclear dihalogen, two possible complexes exist, viz., S=C=S...XY and S=C=S...YX. The calculated structures, vibrational properties, and binding energetics of the complexes are analyzed, and the NBO formalism is used to interpret their bonding properties. The IR spectra of the complexes thus simulated provided vital guidance for the interpretation of the matrix spectra. For example, complexation was predicted and observed (i) to induce red shifts of the principal absorptions associated with both the CS2 and XY components and (ii) to result, through the change in symmetry, in activation of some modes that are IR-silent for the free components.     

Novel halogen and interhalogen adducts of nanoscale magnesium oxide

The difference in the adsorption properties of magnesium oxide in two different physical forms--large micron-sized crystals (CM-MgO) and nanoscale crystals (AP-MgO)--is described. The highly energetic surface of the nanoparticles is significantly more active than the bulk surface in adsorption of nonpolar halogens (Cl(2), Br(2), and I(2)) and dipole interhalogen molecules (ICl, IBr, and ICl(3)). The nanocrystalline and microcrystalline MgO adducts with halogens and interhalogens were characterized by thermogravimetric analysis (TGA), UV-vis and Raman spectroscopies, and transmission electron microscopy (TEM). The bonds of the adsorbates were considerably strained upon adsorption on the nanocrystalline MgO without a molecular dissociation. The results presented in the paper explain the enhanced reactivities of the nanoscale MgO, halogen adducts as halogenating agents of organic molecules and their noticeable biocidal activity.     

Additions electrophiles sur les esters acetyleniques et alleniques—IV : Addition des halogenes et des halogenures de sulfenyle sur le butyne-3 oate d'ethyle

Ethyl but-3-ynoate undergoes electrophilic additions of BrCl and of ICl to give CHXCClCH₂COOEt E (X = Br or I). The addition of sulfenyl halides RSY follows the opposite orientation and leads to CHYCSRCH₂COOEt E (Y = Cl or Br, R = Et or Ph). In the case of IBr, both CHICBrCH₂COOEt E and CHBrClCH₂;COOEt E are obtained.A mechanistic interprétation of these results is supported by both the orientation and the kinetic order of the addition: PhSCl reacts by an Ad_E2 process, whereas ICl addition involves a combination of Ad_E3 and Ad_E4 mechanisms.     

A study of the atmospherically important reactions of dimethylsulfide (DMS) with I2 and ICl using infrared matrix isolation spectroscopy and electronic structure calculations

The reactions of dimethylsulfide (DMS) with molecular iodine (I(2)) and iodine monochloride (ICl) have been studied by infrared matrix isolation spectroscopy by co-condensation of the reagents in an inert gas matrix. Molecular adducts of DMS + I(2) and DMS + ICl have also been prepared using standard synthetic methods. The vapour above each of these adducts trapped in an inert gas matrix gave the same infrared spectrum as that recorded for the corresponding co-condensation reaction. In each case, the infrared spectrum has been interpreted in terms of a van der Waals adduct, DMS?:?I(2) and DMS?:?ICl, with the aid of infrared spectra computed for their minimum energy structures at the MP2 level. Computed relative energies of minima and transition states on the potential energy surfaces of these reactions were used to understand why they do not proceed further than the reactant complexes DMS?:?I(2) and DMS?:?ICl. The main findings of this research are compared with results obtained earlier for the DMS + Cl(2) and DMS + Br(2) reactions, and the atmospheric implications of the conclusions are also considered.     

Synthesis and characterization of cyclopentadienyl transition metal halides,part I,vanadium halides

Summary Reactions between -Cp₂V and PX₃ (X=Cl, Br or I) yield the corresponding dihalogenated derivatives -Cp₂VX₂ (X=Cl, Br or I). The oxidative addition of ICl and IBr to -Cp₂V gives mixed halogenated derivatives -Cp₂VIX (X=Cl or Br). All the compounds have been characterized by elemental analyses, magnetic moment measurements and i.r. and e.p.r. spectra.     

Synthesis and characterization of cyclopentadienyl halides of transition metals: Part II,chromium halides

Summary -Cp₂Cr reacts with PX₃ (X = Cl, Br or I) to give monocyclopentadienylchromium(III) derivatives -CpCrX₂ (X = Cl, Br or I), while oxidative additions of IBr and ICl to -Cp₂Cr give the corresponding mixed halogenated derivatives, -Cp₂CrIX (X = Cl or Br). All products have been characterized by elemental analyses, magnetic moment measurements and by i.r. and e.p.r. spectra.     

Activation of C--H... Halogen (Cl, Br, and I) hydrogen bonds at the organic/inorganic interface in fluorinated tetrathiafulvalenes salts

The electrocrystallization of fluorinated bis(2,2'-difluoropropylenedithio)tetrathiafulvalene (1) in the presence of linear (ICl2-, IBr2-, I2Br-) or cluster ([Mo6Cl14]2-) anions affords 1:1 and 2:1 cation radical salts such as [1][ICl2] and [1]2[Mo6Cl14].(CH3CN)2. In both salts, the 1*+ radical ion adopts a boat conformation and envelops the anion through C-H...Hal(anion) (Hal(anion) = Cl, Br, I) hydrogen bonds. This demonstrates the activating role of the neighboring electron-withdrawing CF2 moieties in the stabilization of bi- or trimolecular neutral entities. With smaller linear anions, fluorine segregation controls the solid-state associations of the bimolecular [1]*+[X] entities, and gives rise to layered materials with a limited overlap interaction between the open-shell organic cations and magnetic spin chain behavior. With the larger [Mo6Cl14]2 ions, a strong overlap interaction between radical cations gives rise to diamagnetic [1]2(2+) dimers, which alternate with the cluster anions to form hybrid organic/inorganic ...[1]2(2+)[Mo6Cl14]2... chains. This behavior is also observed in [2]2(2+)[Mo6Cl14]2-.(CH2Cl2)2, in which compound 2 is the unsymmetrically substituted (ethylenedithio)(2,2'-difluoropropylenedithio)tetrathiafulvalene. On the other hand, the unsymmetrically substituted 2,2'-difluoropropylenedithiotetrathiafulvalene (3) affords a mixed-valence 4:1 salt with [Mo6Cl14]2, which is formulated as [3]4[Mo6Cl14].(CH3CN)2. This semiconducting salt is characterized by the coexistence of both the fluorine/fluorine segregation (with solvent inclusion) and the organic/inorganic segregation (with delocalized overlap interactions). Both Csp2-H...Cl and Csp3-H...Cl hydrogen bonds facilitate the stabilization of the organic/inorganic interface and the presence of conducting organic slabs.     

Interhalogens (ICl/IBr) and AgOTf in thioglycoside activation; synthesis of bislactam analogues of ganglioside GD3

The novel promoter system IX/AgOTf (X = Cl or Br) has been evaluated in the synthesis of two bislactam analogues of GD3. We have carried out two high-yielding galactosylations in 97% and 98% yield, respectively, using ICl/AgOTf, and four sialylations in 93%, 59%, 40%, and 44% yield, using IBr/AgOTf. The choice of interhalogen (IX) is determined by the donor type used in the glycosylation. We also report some mechanistic investigations leading to further optimization of the IX/AgOTf promoter system.     

A unique case of oxidative addition of interhalogens IX (X=Cl, Br) to organodiselone ligands: nature of the chemical bonding in asymmetric I-Se-X polarised hypervalent systems

The reactivity of the imidazoline-2-selone derivatives 1,1'-methylenebis(3-methyl-4-imidazoline-2-selone) (D1) and 1,2-ethylenebis(3-methyl-4-imidazoline-2-selone) (D2) towards the interhalogens IBr and ICl has been investigated in the solid state with the aim of synthesising "T-shaped" hypervalent chalcogen compounds featuring the extremely rare linear asymmetric I-E-X moieties (E=S, Se; X=Br, Cl). X-ray diffraction analysis and FT-Raman measurements provided a clear indication of the presence in the compounds obtained of discrete molecular adducts containing I-Se-Br and I-Se-Cl hypervalent moieties following a unique oxidative addition of interhalogens IX (X=Cl, Br) to the organoselone ligands. In all asymmetric hypervalent systems isolated, a strong polarisation was observed, with longer bond lengths at the selenium atom involving the most electronegative halogen. A topological electron density analysis on model compounds based on the quantum theory of atoms-in-molecules (QTAIM) and electron localisation function (ELF) established the three-centre-four-electron (3c-4e) nature of the bonding in these very polarised selenium hypervalent systems and new criteria were suggested to define and ascertain the hypervalency of the selenium atoms in these and related halogen and interhalogen adducts.     

Electronic Structure and Properties of Trihalogen Cations X(3)(+) and XY(2)(+) (X, Y = F, Cl, Br, I)

Electronic structures, charge distributions, geometries, valence force constants, and vibrational frequencies of the homoatomic clusters F(3)(+), Cl(3)(+), Br(3)(+), and I(3)(+) and of the heteroatomic clusters ClF(2)(+), BrF(2)(+), IF(2)(+), BrCl(2)(+), ICl(2)(+), and IBr(2)(+) were determined. The self-consistent field approach extended by MP2-correlation energy or density-functional corrections was applied using various basis sets. It was found that d- and f-type polarization functions play a crucial role as in some other halogen compounds. The MP2 approach yields the most satisfactory results. The effect of the crystalline environment surrounding the Cl(3)(+), Br(3)(+), and I(3)(+) species is successfully simulated by a Madelung potential. Frequencies calculated in the crystal field are in reasonable agreement with the more reliable ones among the experimental results. Coupling force constants were determined. They are not consistent with some empirical rules. Bonding and charge distributions of the formally mixed-valence systems X(+)Y(2)(0) are discussed. X(+) behaves like a divalent chalcogen with high electronegativity. Each of the X(+)-Y bonds in XY(2)(+) is very similar to the bond in X-Y. We predict the experimentally unknown F(3)(+) to be stable in vacuum but not in the solid state. Structures and frequencies of XY(2)(+) species, which are as yet unknown, are also predicted.     

Syntheses of isochromenes and naphthalenes by electrophilic cyclization of acetylenic arenecarboxaldehydes

Highly substituted 1H-isochromenes, isobenzofurans, and pyranopyridines can be prepared by allowing o-(1-alkynyl)arenecarboxaldehydes and ketones to react with I2, ICl, NIS, Br2, NBS, p-O2NC6H4SCl, or PhSeBr and various alcohols or carbon-based nucleophiles at room temperature. Naphthyl ketones and iodides are also readily prepared by the reaction of 2-(1-alkynyl)arenecarboxaldehydes with I2 and simple olefins or alkynes.