The reaction of eremanthin and isoeremanthin with bromine. Unprecedented simultaneous addition of Br2 to two isolated but topographically related double bonds.

The reaction of $\text{1}$ with Br₂ in CHCl₃ proceeds with the simultaneous and stereospecific incorporation of two moles of Br₂ to give $\text{2}$ thus providing strong experimental evidence for the existence of Br₃.     

Preparation of halo-F-methanes via potassium fluoride-halogen cleavage of halo-F-methylphosphonium salts

Treatment of halo-$\text{F}$-methylphosphonium salts with potassium fluoride and halogen (I₂, Br₂, ICl, IBr) gives modest yields of halo-$\text{F}$-methanes. This method of preparation augments the classical Hunsdiecker approach to these materials.     

Thermal investigation of diamine complexes of Zn(II) in the solid state

The complexes [Zn(en)₃]X2·n H₂O, where en = ethylenediamine, X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄, n = 1 or 0.5, and [Zn(tn)₂]X₂·n H₂O, where tn=1,3-diaminopropane, X=Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄, n = 0 or 0.25, have been synthesized and their thermal investigations carried out. The complexes were characterized by elemental analysis and IR spectral data. These complexes have been observed to decompose through several isolable as well as non-isolable complex species as intermediates during heating. [Zn(tn)₂]SO₄ undergoes solid-state phase transition in the temperature range 126–145°C. ZnenSO₄ and ZntnX₂ (X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄) have been synthesized pyrolytically in the solid state from their corresponding mother diamine complexes. ZnenSO₄ and ZntnX₂ (X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄) complexes decompose through non-isolable hemidiamine species. ZnX₂ (X = Cl^? or Br^?) complexes of tn undergo melting after formation of the monodiamine species. In contrast, the corresponding en complexes undergo melting at non-stoichiometric composition. Diamine (en or tn) is found to be bridging in all monodiamine (en or tn) complexes; whilst their mother complexes possess chelated en or tn. The thermal stability sequence of en and tn complexes of Zn(II) is ZnCl₂ < ZnBr₂ < ZnSO₄. ΔH values are reported for some steps of decomposition. Possible mechanistic paths have been reported for each step of decomposition.     

The hydrolysis of dibromofluoromethyltriphenylphosphonium bromide

Hydrolysis of [Ph₃$\text{P}\text{+}$PCFBr₂]Br^? afforded a high yield of dibromofluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine gave evidence that the mechanism of this reaction proceeds $\text{via}$ the dibromofluoromethide ion and not $\text{via}$ a bromofluorocarbene intermediate.     

Collisional deactivation of laser-excited Br*(2P12) atoms with halogen and interhalogen molecules

Deactivation rates of spin-orbit excited Br*(²P_{$\text{1}\text{2}$}) atoms by halogens I₂, Br₂, and Cl₂ and interhalogens IBr, ICl and BrCl have been measured by laser-excited, time-resolved infrared emission techniques. The results are effectively explained in terms of a collision complex formation model.     

Some remarkable oxidations of 2,3,5,6-tetrachloro-p-phenylenediamine,and products therefrom

The oxidation of 2,3,5,6-tetrachloro-$\text{p}$-phenylenediamine with Cl₂ or Br₂ in CCl₄ containing I₂ affords unusual quinoniminium salts displaying remarkable chemical behaviour.     

Group IB organometallic chemistry: XVI. Complex formation between 2-(dimethylamino)-phenylcopper with copper(I) or silver halides. Synthesis and structural characterization of hexanuclear (2-Me2NC6H4)4Cu6-nMnX2 (M = Cu or Ag) cluster compounds

The $\text{2}\text{1}$ complexes (2RCu · MX) between 2-(dimethylamino)phenylcopper (RCu) and CuX (X = Cl, Br or I) or AgBr have been prepared in two ways (i) from the $\text{2}\text{3}$ reaction of 2-(dimethylamino)phenyllithium with cuprous halide and (ii) from the reaction of RCu with excess of the metalIB halide.The structure of bis[(2-dimethylamino)phenylcopper] cuprous bromide, which is dimeric (R₄Cu₆Br₂) in the solid state, has been determined by X-ray analysis. The bonding in this hexanuclear cluster (CuCu ranging from 2.48 to 2.70 Å, multicenter bonded aryl groups) is discussed. Molecular weight determinations and ¹H NMR spectroscopy reveal a similar hexanuclear structure for the R₄Cu₆X₂ complexes in benzene solution. NMR spectroscopy indicates that in solution the mixed-metal cluster compounds R₄Cu_6-nAg_nBr₂ are not stable but enter into interaggregate exchange reactions. A possible pathway involving trinuclear species R₂Cu_3-nAg_nX as intermediates is proposed.     

Preparation and synthetic utility of fluorinated phosphonium salts,bisphosphonium salts and phosphoranium salts

The synthesis and mechanism of formation of phosphonium salts of the type [R₃$\text{P}\text{+}$CFXY]Z^? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), $\text{bis}$-phosphonium salts of the type [R₃$\text{P}\text{+}$CF₂$\text{P}\text{+}$R₃]2Br^?, and phosphoranium salts of the type [R₃$\text{P}\text{+}$$\text{C}\text{?}$F$\text{P}\text{+}$R₃]X^? (X = Br, Cl) will be presented. The applicability of these substrates in the generation of useful nucleophilic or electrophilic synthetic intermediates will be discussed.     

Electronic-to-vibrational energy transfer from Br (42P12 to HF

Room temperature experiments have measured the rate of electronic-to-vibrational energy transfer between spin—orbit excited Br(4²P_{$\text{1}\text{2}$}) and HF. The Br^* + HF quenching rate is very fast, (1.1 ± 0.2) × 10⁶ s^?1 torr^?1, due to a near resonance between the spin—orbit splitting and the vibrational spacing. The majority of the Br^* spin—orbit energy goes directly into HF vibration.     

A practical synthesis of fluoromethyltriphenylphosphonium salts

A practical synthesis of [Ph₃$\text{P}\text{+}$CH₂F]BF₄^? is reported $\text{via}$ two routes, $\text{via}$ fluorination of [Ph₃$\text{P}\text{+}$CH₂OH]BF₄^? with DAST or $\text{via}$ hydrolysis of the phosphoranium salt, [Ph₃$\text{P}\text{+}$$\text{C}$F$\text{P}\text{+}$Ph₃]Br^?.     

The photodecomposition of platinacycloalkanes in solution: II. 1,4-butanediylplatinum(II) and (IV) compounds

The products of the photolysis of a number of platinacyclopentanes in solution at 25°C under a variety of conditions have been determined. With [I₂P$\text{tCH}{}_2\text{CH}{}_2\text{CH}{}_2\text{C}$H₂(L₂)] (L = PMe₂Ph, PPh₃) in CH₂Cl₂, CH₂Br₂ and (CH₃)₂SO the hydrocarbon products are exclusively ethylene and but-1-ene. Formation of the latter through a 1,3-hydrogen shift is preceded by phosphine ligand dissociation. The photolysis of [ICH₃P$\text{tCH}{}_2\text{CH}{}_2\text{C}$H₂(L₂)] gave methane, ethylene, but-1-ene and n-pentane together with a little n-butane, the methane being formed from internal hydrogen abstraction by the CH₃ group in the excited reactant molecule. Photodecomposition of the platinum(II) compounds [P$\text{tCH}{}_2\text{CH}{}_2\text{CH}{}_2\text{C}$H₂(L₂)] (L = (PMe₂Ph)₂, (PPh₃)₂, Ph₂PCH₂CH₂PPh₂) gave ethylene, but-1-ene, pent-1-ene (with the halogenated solvents) and with some systems appreciable yields of n-butane, the latter being the results of internal abstraction of two hydrogen atoms by the C₄H₈ moiety. The formation of pentene is probably preceeded by the addition of CH₂Cl₂ or CH₂Br₂ to the excited reactant molecule. Addition of diphenylphosphine promotes the production of n-butane.     

Coulometric titration of iodide and iodine with electrolytically generated hypobromite

Conditions for the quantitative coulometric titration of iodide and iodine with electrolytically generated hypobromite in the presence of borax buffer have been established. Iodide and iodine are oxidized to iodate. The method, with biamperometric indication of the equivalence point, was successfully applied for a wide range of iodide concentrations (6.21–2115μg with reliability intervals of ±0.21–±11μg) and iodine concentrations (24.26–3311μg with reliability intervals of ±0.36–±11.7μg). The determinations are accurate and sensitive even in the presence of large amounts of bromides and chlorides ($\text{Br}{}^{\mathrm{?}}\text{I}{}^{\mathrm{?}}$= 1.2·10⁶ and $\text{C}\text{l}$^?I^?=4.0·10^{3), as well as in the presence of oxidizing agents such as IO₃?, BrO₃? and CrO₄2? ($\text{I}\text{O}$₃?/I₂)=3.2·105, $\text{I}\text{O}$₃?/I₂=3.1·103, $\text{Br}\text{O}$-₃/I₂}=1.1·10⁴ and $\text{Cr}\text{O}$^2-₄/I₂=1.0·10⁴, as was confirmed by statistical tests. The oxidation mechanism under the conditions of coulometric titrations is discussed.     

The hydrolysis of bromodifluoromethyltriphenylphosphonium bromide [1]

Hydrolysis of [Ph₃$\text{P}\text{+}$CF₂Br]Br^? afforded a high yield of bromodifluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine or sodium iodide gave unequivocal evidence that the mechanism for this reaction proceeds through a difluorocarbene intermediate.     

X-ray study of Hg2Cl2Br2 and HgCl2HgBr2 reactions in solid state

The reactions (I) Hg₂Cl₂(s) + Br₂(g) and (II) HgCl₂(s) + HgBr₂(s) have been investigated by an X-ray method. Both the reactions yield two forms of the mixed halide HgClBr, designated as α-HgClBr and β-HgClBr. The cell parameters of the two are as follows:α-HgClBr: $\text{a = 6.196}\text{A}\text{?}$, $\text{b = 13.12}\text{A}\text{?}$, $\text{c = 4.37}\text{A}\text{?}$, z = 4, ? = 5.91 g/cm³. The powder pattern and cell parameters are similar to that of HgCl₂. Therefore it is probable that the chlorine atoms, in the linear halogenHghalogen molecules of HgCl₂ structure have been replaced by bromines, and since the radius of the bromine atom is larger than that of chlorine, the lattice is larger in this case.β-HgClBr: $\text{a = 6.78}\text{A}\text{?}$, $\text{b = 13.175}\text{A}\text{?}$, $\text{c = 4.17}\text{A}\text{?}$, z = 4, ? = 5.40. These parameters are the same as those reported in the literature for β-Hg(ClBr)₂, and its X-ray powder pattern is similar to HgCl₂. Therefore this phase also has linear halogenHghalogen molecules but the distribution of Cl and Br atoms is perhaps random.Heating the products (I) and (II) up to the melting point increases the amount of α phase and decreases the β phase, whereas crystallization increases the β phase. DTA study has supported the X-ray findings.     

A 29Si, 13C and 1H NMR study of the interaction of various halotrimethylsilanes and trimethylsilyl triflate with dimethyl formamide and acetonitrile,a comment on the nucleophile induced racemisation of halosilanes

The ²⁹Si, ¹³C and ¹H NMR spectra of $\text{1}\text{1}$ mixtures of Me₃SiI and Me₃SiOSO₂CF₃ with DMF in CD₂Cl₂ show signals that are consistent with the formation of Me₃SiO$\text{C}\text{+}$H(NMe₂)X^? but not with penta- or hexa-coordinate silicon species. The spectra of a $\text{1}\text{1}$ mixture of Me₃SiBr and DMF show a rapidly exchanging, equilibrium mixture of Me₃SiO$\text{C}\text{+}$H(NMe₂)Br^? and starting materials. No strong evidence for salt formation between DMF and Me₃SiCl was obtained. The spectra of Me₃SiX (X = I, Br, Cl, OSO₂CF₃) in CD₃CN indicate that neither adduct formation nor extra coordination at silicon is significant.     

Stereochemistry of nucleophilic additions to hexafluoro-2-butyne

Base-catalysed additions of alcohols to F-2-butyne (1) give mainly products of $\text{trans}$-addition while $\text{cis}$-addition predominates in uncatalysed additions of alcohols carried out in a diluent. The stereochemistry of addition of diethylamine is very dependent on the solvent used and $\text{cis}$- or $\text{trans}$-addition may predominate. Stepwise and concerted mechanisms are advanced to account for these observations. Nucleophilic addition of sulphur to (1) gives F-tetramethylthiophene (68%) and hydration gives CF₃CH₂COCF₃ (91%).     

Perfluoroalkyl derivatives of nitrogen. Part LI [1]. Reaction of the N-halogenobistrifluoromethylamines (CF3)2NX (X=Cl,Br) with norbornadiene

Reaction of the amines (CF₃)₂NX (X=Cl,Br) with norbornadiene either in solvent (CH₂Cl₂) at ?78 °C in the dark or in the vapour phase at 20 °C in daylight gives a mixture of 3-halogeno-5-($\text{NN}$-bistrifluoromethylamino)nortricyclene ($\text{exo}$, $\text{endo}$-and $\text{exo}$, $\text{exo}$-isomers) and $\text{exo}$-5-($\text{NN}$-bistrifluoromethylamino)- $\text{anti}$-7-halogenonorbornene in quantitative yield formed $\text{via}$ halonium ion addition to the diene. The reaction of the amine (CF₃)₂NBr in solvent Me₂O or Et₂O at ?78 °C in the dark gives the same products in low yield, together with 3-bromo-5-alkoxynortricyclene ($\text{exo}$, $\text{endo}$- and $\text{exo}$, $\text{exo}$-isomers) and the amine (CF₃)₂NR (R=Me, Et) in high yield.