Halide Transfer Research Articles

ChemInform Abstract: Novel Aspects of η′‐Diiodine Coordination and Diiodine Oxidative Addition to Platinum(II) and Halide Transfer Oxidation Reactions of Organoplatinum(II) with CuIIX2

ChemInformVolume 21, Issue 47 Reviews ChemInform Abstract: Novel Aspects of η′-Diiodine Coordination and Diiodine Oxidative Addition to Platinum(II) and Halide Transfer Oxidation Reactions of Organoplatinum(II) with CuIIX2 G. VAN KOTEN, G. VAN KOTEN Dep. Metal Med. Synth., Univ., 3584 CH Utrecht, NetherlandsSearch for more papers by this author G. VAN KOTEN, G. VAN KOTEN Dep. Metal Med. Synth., Univ., 3584 CH Utrecht, NetherlandsSearch for more papers by this author First published: November 20, 1990 https://doi.org/10.1002/chin.199047278Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue47November 20, 1990 RelatedInformation

Silver ion-solvent complexing in acetylacetone and ionic Gibbs energies of transfer

For the purpose of elucidating ion-solvent interactions in acetylacetone (2,4-pentanedione, Hacac), the complex formation constants (β n ) of the silver ion in Hacac with some donor solvents have been determined at 298 K by potentiometry. The standard molar Gibbs energies of transfer (Δ G tr°) of silver, halide and tetraphenylborate ions from Hacac to 14 other solvents were also determined potentiometrically and correlated with some solvent parameters. The correlation between the β n and (Δ G tr°) values of the silver ion can be interpreted quantitatively on the basis of the coordination model of ionic solvation. Hacac was used as the reference solvent for silver ion complexing and ionic solvent transfer because it is a less basic and less acidic amphiprotic solvent.

Thermodynamics of transfer of hydrogen halides (hydrogen chloride, hydrogen bromide) in glycerol-dimethylformamide mixtures from electromotive force measurements

Les potentiels standard du couple Ag/AgX avec X=Cl − ou Br − dans un melange glycerol/DMF sont determines entre 25 et 35 o C par des mesures de force electromotrice

Novel aspects of η'-diiodine coordination and diiodine oxidative addition to platinum(II) and halide transfer oxidation reactions of organo-platinum(II) with CuIIX2

Abstract

Alkyl halide transfer from palladium(IV) to platinum(II) and a study of reactivity, selectivity, and mechanism in this and related reactions

Kinetic studies of the oxidative addition of MeI or PhCH2Br to [MMe2(L2)] (M = Pd or Pt, L2 = 2,2'-bipyridine or 1,lO-phenanthroline) indicate that the reactions occur by the SN2 mechanism, and the reactions occur 7-22 times faster when M = Pt over Pd and 1.2-2.2 times faster when L2 = phen over bpy. Reductive elimination from [PdBrMe2(CH2Ph)(L2)] in the solid state occurs to give both Me-Me and PhCH2Me, and there is a preference for methyl group loss. Thermochemical studies indicate that CH3-CH3 loss gives DH = -108 +/- 4 kJ mol-' but PhCH2-CH3 loss gives DH = -48 +/- 12 kJ mol-', indicating a relatively strong PhCH2-Pd bond. The complexes [PdIMe3(L2)] or [PdBrMe2(CH2Ph)(L2)] react rapidly with [PtMe2(L2)] by alkyl halide transfer. Kinetic studies have shown that the major route involves loss of halide from palladium(IV) in a preequilibrium step, followed by SN2 attack by [PtMe2(L2)] on an alkyl group of [PdMe3(L2)]+ or [PdMe2(CH2Ph)(L2)]+. In the latter case, benzyl group transfer is preferred over methyl group transfer.

ChemInform Abstract: Halide Redistribution Reactions of Rhodium(III) and Iridium(III) Complexes of the Type mer‐(MX3(PMe2Ph)3) (X: Cl or I).

Abstract Halide exchange between mer -[RhCl 3 L 3 ] and mer -[RhI 3 L 3 ] (L=PMe 2 Ph) in chloroform at room temperature gives an equilibrium mixture of these two compounds and one specific isomer each ( trans, mer ) of [RhCl 2 IL 3 ] and [RhClI 2 L 3 ] such that there is an approximately equal quantity of each species in solution after several hours. This exchange is catalysed by the aqua-complex [RhCl 2 (H 2 O)L 3 ][ClO 4 ] or by [(Ph 3 P) 2 N]Cl {[PPN]Cl}. The mechanism of exchange catalysed by the aqua-complex involves halide transfer via intermediates of the type [L 3 X 2 RhXRhX 2 L 3 ] + (X=Cl or I). Transfer is very rapid, rapid enough to give total 1 H NMR coalescence of PMe 2 Ph signals in mixtures of [RhCl 3 L 3 ] and [RhCl 2 (H 2 O)L 3 ] [ClO 4 ]. A further uncatalysed halide exchange occurs slowly to give a mixture of [RhCl 3 L 3 ], [RhI 3 L 3 ], and both possible isomers ( trans,mer and cis,mer ) of the two mixed halide complexes. The composition of the equilibrium mixture indicates a six-fold preference for chloride over iodide in the labile site trans to PMe 2 Ph. Possible mechanisms for this slow process are discussed. With iridium only the first process occurs at measurable rates.

Halide redistribution reactions of rhodium(III) and iridium(III) complexes of the type mer-[MX 3(PMe 2Ph) 3] (X = Cl or I)

Halide exchange between mer-[RhCl 3L 3] and mer-[RhI 3L 3] (L=PMe 2Ph) in chloroform at room temperature gives an equilibrium mixture of these two compounds and one specific isomer each ( trans, mer) of [RhCl 2IL 3] and [RhClI 2L 3] such that there is an approximately equal quantity of each species in solution after several hours. This exchange is catalysed by the aqua-complex [RhCl 2(H 2O)L 3][ClO 4] or by [(Ph 3P) 2N]Cl {[PPN]Cl}. The mechanism of exchange catalysed by the aqua-complex involves halide transfer via intermediates of the type [L 3X 2RhXRhX 2L 3] + (X=Cl or I). Transfer is very rapid, rapid enough to give total 1H NMR coalescence of PMe 2Ph signals in mixtures of [RhCl 3L 3] and [RhCl 2(H 2O)L 3] [ClO 4]. A further uncatalysed halide exchange occurs slowly to give a mixture of [RhCl 3L 3], [RhI 3L 3], and both possible isomers ( trans,mer and cis,mer) of the two mixed halide complexes. The composition of the equilibrium mixture indicates a six-fold preference for chloride over iodide in the labile site trans to PMe 2Ph. Possible mechanisms for this slow process are discussed. With iridium only the first process occurs at measurable rates.

Energy requirements for a chemical reaction. I. Halide ion transfer to antimony pentafluoride

Using crossed seeded nozzle beams we have examined the energy dependence of the cross section for the reaction SbF5+RX→SbF5X−+R+, where X is a halogen and R an organic radical. By using a range of carrier gases in the two beams and by varying the nozzle temperature and the beam intersection angle, we can separately vary the relative translational energy and the vibrational temperatures of the beams. Near the threshold, vibrational energy seems to play a very important role. At energies well above threshold, the reactive cross section appears to depend largely on translational energy. We explain this by assuming that the reaction takes place on two potential energy surfaces. By choosing RX properly, the R+ product will decompose. In two cases we observe that, although vibrational energy in RX has a minor effect on the halide abstraction, it is very important in the subsequent decomposition of R+.

Ionic solvation in water–cosolvent mixtures. Part 13.—Free energies of transfer of single ions from water into water–tetrahydrofuran mixtures

The free energy of transfer of the proton between water and water-rich mixtures of water and tetrahydrofuran (THF), ΔG°t(H+), has been found by examining spectrophotometrically the redistribution of solvent molecules around the aqua-proton after the latter charged sphere has been transferred into the mixture. Values for ΔG°t(HX) calculated from electrochemical data are combined with the new ΔG°t(H+) to produce ΔG°t(X–) for the transfer of halide ions and of OH– from water into water–THF mixtures. These ΔG°t(X–) are then used with values for ΔG°t(MX) derived from electrochemical and vapour-pressure measurements to give values for ΔG°t(M+) for alkali-metal ions and for Bun4N+ ions. pK values for two carboxylic acids and for a range of anilinium cations in water–THF mixtures are combined with ΔG°t(M+) to produce ΔG°t(i)e the free energy of transfer from water into water–THF of the charge on the carboxylate anion or the anilinium cation with the effect of transferring the molecular bulk of the ion removed.

Enthalpies of transfer of tetra-alkylammonium halides from water to water–propan-1-ol mixtures at 25 °C

The enthalpies of transfer of several tetra-alkylammonium halides in water–propan-1-ol mixtures have been measured. These data are analysed in terms of recently developed solvation theory. The results of this analysis indicate that solvation of the electrolytes involves a net breaking of solvent–solvent bonds at all solvent compositions. The extent of bond-breaking increases dramatically with the size of the tetra-alkylammonium ion in the highly aqueous solvent systems but is relatively insensitive to the size of the cation in solvents with higher alcohol content. The results for the propan-1-ol system are compared to those for t-butanol–water solvent systems.

The mechanism of electrical conductivity along polyhalide chains

A theoretical study of possible mechanisms for electrical conduction along polyhalide chains [X − 3 ] ∞ is presented. The proposed steps are the reduction of an X − 3 ion to X 2− 3 ; subsequent migration of a halide ion from the X 2− 3 unit to its nearest ne no substantial barrier; electron transfer from an elongated X 2− 3 to its neighboring X 2− 3 ; oxidation of an X 2− 4 species t the backmigration of a halogen atom. The non-existence of a barrier for the halide ion transfer in an isolated chain can be elucidated with the help of tight-binding band calculations on the bulk and by ab initio pseudopotential calculations in the local region, where species like X − 2,X 2− 4 and X − 4 might form as intermediates. The activation in the conduction process should therefor from the steps which take place at the electrodes or from interactions with the cationic sublattice in the solid.

Free energies and entropies of transfer of hydrogen halides from water to aqueous 2-methoxy ethanol and structuredness of the solvents

Standard free energies (ΔGt0) and entropies (ΔSt0) of transfer of HBr and HI from water to some aqueous solutions of 2-methoxy ethanol (ME) have been determined from emf measurements of the cells: Pt, H2 (g, 1 atm)/HBr (m), solvent/AgBr–Ag and Pt, H2 (g, 1 atm)/KOH (m1), KI (m2), solvent/AgI–Ag, respectively, at seven equidistant temperatures ranging from 15 to 45 °C. ΔGt0 values of HBr and HI as well as of HCl obtained from literature, and particularly that of the individual ions obtained by tetraphenylarsonium tetraphenylboron (TATB) assumption, suggest that while H+ is increasingly stabilized by cosolvent-induced larger "basicity", halide ions (X−) are increasingly destabilized by cosolvent-induced decreased "acidity" and the dielectric constant of the mixed solvents compared to that of water. Analysis of the variation of the observed TΔSt0(HX) and particularly of ΔY (= TΔSt0(H+) + TΔS0t.ch (X−), with composition, in the light of Kundu etal's semi-quantitative theory reveals that ME induces breakdown of three dimensional (3D) tetrahedral structures of water at water-rich compositions. This is being followed by an ordered region due to possible H-bonded cosolvent–water complexation and then the usual disordered region due to packing imbalance. Comparison of ΔY(HI)–composition profiles for aqueous mixtures of t-butanol (ButOH), ethylene glycol (EG), and 1,2-dimethoxy ethane (DME) also demonstrates that the remarkable enhancement of 3D water structures by the well known structure promoter ButOH gets succintly diminished when cosolvent ButOH is replaced by EG, ME, and DME, as is expected from structural and electronic considerations of the cosolvents.

Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part 21.—Free energies of transfer of alkali-metal halides in the acetone + water system to 60%(w/w) acetone with cation-selective electrodes

The failure of alkali-metal amalgam electrodes to function satisfactorily in acetone + water mixtures has dictated the use of cation-sensitive glass electrodes to determine ΔGz.ccsh;t, for transfer of alkali-metal halides from water to mixtures containing up to 60%(w/w) acetone. Data for fluorides have been obtained using LaF3 electrodes.

Free energies and entropies of transfer of hydrogen halides from water to aqueous solutions of tetrahydrofuran, dioxane, and 1,2-dimethoxyethane and the structuredness of the solvents

Standard free energies (ΔGt0) and entropies (ΔSt0) of transfer of hydrogen iodide from water to some aqueous solutions of tetrahydrofuran (THF), dioxane (D), and 1,2-dimethoxyethane (DME) have been determined by measuring the emf's of the cell: Pt, H2 (g, 1 atm)|KOH (m1), KI (m2), solvent|AgI, Ag at seven equidistant temperatures ranging from 5 to 35 °C. In each of these ethereal solvent systems ΔGt0 values of HI, as well as of HCl and HBr obtained from the literature, and particularly of the individual ions, suggest that while H+ is increasingly stabilized, halide ions are increasingly destabilized due to the influence of cosolvent-induced larger "basicity" and smaller "acidity" of the mixed solvents compared to that of water, and both conformed to the expected order: D < THF < DME. Moreover, the relative order: Cl− > Br− > I− in all the solvent systems is ascribable to the combined effects of "acid–base" and "soft–soft" interactions and the superimposed quadrupolar interactions in the case of D and the charge transfer to solvent (CTTS) complexation effect, especially on I− in the case of THF. Analysis of the entropie contributions, TΔSt0, and particularly of the relative order of ΔY (≡TΔSt0(H+) + TΔSt,ch0(X−)) for X = Cl, Br, and I, in the light of the semi-quantitative theory proposed earlier by Kundu et al., reveals that at initial compositions, while THF promotes 3D structures of water, both D and DME break down the same; at higher compositions all the cosolvents disrupt the structure as usual due to packing imbalance. The nature and relative positions of ΔY–composition profiles also suggest that while increase of hydrophobic groups of the cosolvents increases the stabilization, increase in hydrophilicity or H-bonding sites decreases the stabilization of the 3D structure of water.

Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part 20.—Enthalpies of transfer of alkali-metal halides in the methanol + water system from enthalpies of dilution

Enthalpies of transfer, ΔH0t, of the alkali-metal chlorides and of sodium bromide and sodium iodide from water to methanol + water mixtures over the whole range of solvent composition have been determined by measuring heats of dilution of concentrated aqueous solutions. Greater precision is achieved than when heats of solution are measured. A submarine calorimeter was used and the concentrated solutions injected with a dispensing pipette. This gave precise results rapidly.Results for sodium chloride obtained by measuring heats of solution were in good agreement with those from heats of dilution. There is fair agreement with the classical work of Slansky except for Li+Cl–.Comparison with ΔG0t and ΔS0t confirms that ΔG0t is the simplest function and suggests that structural effects compensate in ΔH0t and ΔS0t.

Thermodynamics of transfer of hydrogen halides from water to glycerol–water mixtures and the structuredness of the solvents

Standard free energies (ΔGt0) and entropies (ΔSt0) of transfer of HX (X = Br and I) from water to glycerol–water mixtures containing 10, 30, 50, and 70 wt.% glycerol have been determined from emf measurements on the cell: Pt, H2(g, 1 atm)/HX(m), solvent/AgX–Ag at seven equidistant temperatures ranging from 10–40°C. The observed ΔGt0–composition profiles of HBr, HI, and also of HCl obtained from the relevant literature data are essentially similar to those in aquo-alcoholic and aquo-glycolic systems. But the observed short maxima in TΔSt0(HX)–composition profiles with their relative order: HI > HBr > HCl in water-rich compositions and the reverse order at higher proportions of glycerol are indicative of the effect of small structure promoting propensity of glycerol. Comparison of TΔSt0(HI)–composition profiles of methanol, isopropanol, and tert-butyl alcohol on the one hand and that of methanol, ethylene glycol, and glycerol on the other, leads us to suggest that the structure promoting ability of hydrophobic —CH3 group is significantly reduced due to 'specific site hydration' effect when its one H-atom is being replaced by one hydrophilic —OH group. Also, the compositions at which the characteristic maxima appear, either in the former cases or in the latter, are, as expected, the size effect of the co-solvents.

Gas-phase organometallic chemistry. Reactions of Al + with alkyl halides

Gas-phase ion-molecule reactions of Al + with several alkyl halides have been examined using an ion beam appratus. Relative product ion abundances are reported as a function of collision energy over the range 0.5–5 eV. Three types of reactions are observed: (1) halide transfer, (2) dehydrohalogenation, and (3) oxidation. Halide transfer from dichloroalkanes yields chloronium ions, which may eliminate HCl to give allyl cations. Dehydrohalogenation results in elimination of HX with Al + remaining bound to either HX or the alkene which is concomitantly formed. The relative importance of the halide transfer and dehydrohalogenation products is dependent on the reaction thermodynamics and the collision energy. Reaction of Al + with CH 2ClCH 2Cl leads to AlCl 2 + and C 2H 4, a process in which the metal is formally oxidized from the +1 to the +3 state.

Positive and negative ion chemistry of sulfuryl halides

Ion cyclotron resonance techniques are employed in the investigation of positive and negative ion formation and ion-molecule reactions in sulfuryl halides SO 2XY (X, Y = Cl, F). Positive ion reactivity is discussed in terms of the relative Cl and F bond strengths in these species and possible structures of ionic intermediates and products. Electron attachment processes generate halide ion donors such as F 2 −, Cl 2 −, SO 2F − and SO 2Cl − from sulfuryl halides. Negative ion reactivity is dominated by halide transfer reactions. Halide transfer reactions in mixtures with HCN and HCl are examined in an attempt to quantify D(SO 2F −) and D(SO 2Cl −).

Free energies and entropies of transfer of hydrogen halides from water to aqueous alcohols and the structure of aquo-organic solvents

Free energies ΔG0t and entropies ΔS0t of transfer of HCl from water to ethanol + water and propan-2-ol + water mixtures have been determined from the standard potentials E0 of the cell Pt, H2(g, 1 atm)|HCl (m), solvent|AgCl–Ag. ΔG0t values for hydrogen and halide ions have been obtained by a simultaneous extrapolation procedure applied to ΔG0t(HCl), ΔG0t(HBr) and ΔG0t(HI), values of the last two being taken from previous papers. The chemical parts of the ionic ΔG0t values in these and two other aquo-alcoholic systems have been interpreted in terms of ion-solvent interactions of the acid–base type modified by solvent structural effects.

The gas-phase ion chemistry of carbonyl compounds: Formyl fluoride and a binary mixture of H 2CO [sbnd]F 2CO or H 2CO [sbnd]Cl 2CO

The gas-phase ion chemistry of formyl fluoride has been studied by ion cyclotron resonance mass spectrometry. The most abundant ions observed in the positive ion mass spectrum were: HFCO +, HCO +, FCO + and CO +. The main positive ion—molecule reactions in HFCO were the protonation of the neutral molecule by HFCO + and HCO + with rates of (2.5 ± 0.2) × 10 −9 and (0.7 ± 0.1) × 10 −9 cm 3 s −1, respectively. Tertiary ions formed by reactions of the protonated molecule are CH 3F 2O + and the protonated dimer (HFCO) 2H +, which either stabilized by collision or dissociated by ejection of hydrogen, oxygen or fluorine atoms. The only primary negative ion formed by electron impact was FCO −. Its ionization efficiency curve showed a peak arising from resonant dissociative electron attachment. A secondary ion COF 2H − was formed by the reaction of FCO − with HFCO. Ion—molecule reactions in mixtures of H 2CO and F 2CO or Cl 2CO were also studied. Proton and halide transfer reactions were observed in both mixtures, but formation of protonated mixed dimers was not observed. The limits of the heats of formation of the ions CO(H, F) 3 − and CO(H, Cl) 3 − were estimated.