Demercuriation reactions of the complexes [(PPh3)2RPtHgR′] containing platinum-mercury bonds

The compounds [(PPh₃)₂,RPtHgR′] (R = CH₃, R′= 2,5-C₆H₃Cl₂, 2,3,4- and 2,4,6-C₆H₂Cl₃, 2,3,4,5-, 2,3,4,6- and 2,3,5,6-C₆HCl₄, C₆Cl₅; R = Et, R′ = 2,5-C₆H₃Cl₂, 2,4,6-C₆H₂Cl₃; R = 2-C₆H₄Cl, R′=2-C₆H₄(CH₃)) have been prepared by the reactions of RHgR′ with Pt(PPh₃)₃, in order to study their possible use as intermediates in the preparation of diorganoplatinum complexes with different organic ligands. The dependence of J(³¹P-¹⁹⁵Pt) on slight differences in the electronic character of the ligand R′ in the series of compounds [(PPh₃)₂(CH₃)Pt-HgR′] has been studied.     

Shock tube and modeling study of 1,3-butadiene pyrolysis

1,3-Butadiene (1,3-C₄H₆) was heated behind reflected shock waves over the temperature range of 1200–1700 K and the total density range of 1.3 × 10⁻⁵ −2.9 × 10⁻⁵ mol/cm³. Reaction products were analyzed by gas-chromatography. The concentration change of 1,3-butadiene was followed by UV kinetic absorption spectroscopy at 230 nm and by quadrupole mass spectrometry. The major products were C₂H₂, C₂H_4, C₄H₄, and CH₄. The yield of CH₄ for a 0.5% 1,3-C₄H₆ in Ar mixture was more than 10% of the initial 1.3-C₄H₆ concentration above 1500 K. In order to interpret the formation of CH₄ successfully, it was necessary to include the isomerization of 1,3-C₄H₆ to 1,2-butadiene (1,2-C₄H₆) and to include subsequent decomposition of the 1,2-C₄H₆ to C₃H₃ and CH₃. The present data and other shock tube data reported over a wide pressure range were qualitatively modeled with a 89 reaction mechanism, which included the isomerizations of 1,3-C₄H₆ to 1,2-C₄H₆ and 2-butyne (2-C₄H₆). © 1996 John Wiley & Sons, Inc.     

Quasi-two-dimensional organic metals with differently oriented conducting layers

New layered organic conductors based on selenium- and sulfur-containing donor molecules of bis(ethylenedithio)tetraselenafulvalene (BETS) and deuterated bis(ethylenedithio)-tetrathiafulvalene (ET) with tetrahedral anions of divalent metals of the general formula (BETS)₄HgBr₄(1,2-C₆H₄Cl₂), (ET-d₈)₄HgBr₄(C₆H₄Cl₂) and (ET-d₈)₄HgBr₄(C₆H₅X) (where X = Cl, Br) were synthesized using halobenzenes as solvents. The crystal structure of (BETS)₄HgBr₄(C₆H₄Cl₂) was studied at room temperature. A distinctive feature of the crystal structures of the compounds is the alternation of the conducting layers, which differ in direction of the radical cation stacks. The conductivity along the layers is of metallic character with the temperature decrease down to 4.3 K for (BETS)₄HgBr₄(C₆H₄Cl₂) and down to 40—105 K for ET-d₈-based compounds, while in the direction perpendicular to the conducting layers the conductivity is semiconducting. A comparative analysis of the temperature dependence of the resistivity for the compounds (ET)₄HgBr₄(Solvent) (Solvent is 1,2-C₆H₄Cl₂, C₆H₅X), which are based on ET and its deuterated analog, allows one to suggest that the metal—metal phase transitions observed in the 220—285 K range are of different origin: in the compounds containing 1,2-C₆H₄Cl₂ they are due to the ordering of solvent molecules, whereas in the compounds containing C₆H₅X the transitions are associated with rearrangements of the terminal ethylene groups.     

Gas-chromatographic determination of impurities of organic and chlorinated organic compounds and carbon monoxide and dioxide in high-purity hydrogen chloride

A gas-chromatographic procedure was developed for determining impurities (CH₄, C₂H₆, C₃H₈, C₄H₁₀, iso-C₄H₁₀, C₅H₁₂, iso-C₅H₁₂, neo-C₅H₁₂, CH₃Cl, C₂H₅Cl, CH₂Cl₂, CHCl₃, CO, and CO₂) in hydrogen chloride using two columns and a column switching technique in an isothermal mode with a flame ionization detector; the detection limits were 0.01–0.1 ppm. The matrix was separated in a precolumn packed with urea. CO and CO₂ were determined by reaction gas chromatography with their conversion into methane.     

Chlorinated organic derivatives containing MoHg and WHg bonds: Importance of the steric effects in their stabilization

A series of MoHg and WHg bonded complexes [RHgM(CO)₃Cp], (R = 2,4,6-C₆H₂Cl₃,2,3,5,6-C₆,HCl₄ and C₆Cl₅) have been prepared from ClHgR and the salts Na[M(CO)₃)Cp]. When R contains only one ortho chlorine atom (R = 2,5-C₆H₃Cl₂, 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄) a symmetrisation process occurs to give the corresponding HgR₂ and Hg[M(CO)₃Cp)₂2. These results indicate that steric effects are very important in the formation of compounds containing molybdenum- or tungsten—mercury bonds. Complexes of the type [(C₆Cl₅)HgM(CO)₂(PPh₃)Cp] (M = Mo and W) are obtained from [(C₆Cl₅)HgM(CO)₃Cp] and PPh₃ in boiling ethanol.     

Reactivity of polychlorophenylmercury compounds with 1,10-phenanthroline

The action of 1,10-phenanthroline (phen) on the THF solutions of RHgCl (R = 2,5-C₆H₃Cl₂; 2,3,4? and 2,4,6-C₆H₂Cl₃; 2,3,4,5?, 2,3,4,6?, and 2,3,5,6-C₄HCl₄ and C₆Cl₅) gives RHgCl (phen) when R contains two chlorine substituents in ortho (R = 2,4,6-C₆H₂Cl₃; 2,3,4,6?, and 2,3,5,6-C₆HCl₄ and C₆Cl₅), but the symmetrisation reaction occurs when R = 2,5-C₆H₃Cl₂; 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄. The action of phen on HgR₂ only gives HgR₂ (phen) when R = 2,3,4,5-C₆HCl₄. Compounds of the type RHgMe do not react with phen. These results indicate that steric citects are as important as the electronegativity of R in the formation of tetracoordinated mercury compounds.     

Addition–substitution competition in liquid-phase chlorinations

The rate constants of liquid-phase hydrogen abstraction by chlorine atoms from 1,2-C₂H₄Cl₂ relative to those of addition to C₂HCl₃ and to C₂Cl₄ and to that of hydrogen abstraction from cyclohexane have been measured between 250 and 345°K. Assuming a zero activation energy for the addition reactions permits one to calculate the corresponding values for the liquid-phase hydrogen abstraction from the chlorinated ethanes. These values are discussed and compared with the gas-phase data.     

Photochemical arene exchange in the naphthalene complex [CpRu(η<Superscript>6</Superscript>-C <Subscript>10</Subscript>H<Subscript>8</Subscript>)]<Superscript>+</Superscript>

The cation [CpRu(η⁶-C₁₀H₈)]⁺ was shown to exchange naphthalene for other arenes under visible-light irradiation to form the complexes [CpRu (η⁶-arene)]⁺ (arene = C₆H₆, 1,4-C₆H₄Me₂, 1,3,5-C₆H₃Me₃, or 1,2,4,5-C ₆H₂Me₄) in 70–95% yields. The reaction rate of exchange decreases in the series arene = 1,4-C₆H₄Me₂ > C₆H₆ > 1,3,5-C₆H₃Me₃ > 1,2,4,5-C ₆H₂Me₄ >> C₆Me₆ and increases with the coordinating ability of the solvent in the order CH₂Cl₂ < THF—CH₂Cl₂ mixture (1: 1) < acetone.     

Primary processes in the 147-nm photolysis of 1,1-dichloroethane

The room temperature photolysis of 1,1-dichloroethane at 147 nm in the pressure range of 1.34-196.2 torr is characterized almost entirely by the molecular elimination of HCl, Cl₂, and small quantities of H₂. Acetylene is also produced. While it is possible that the C₂H₂ arises, in part, from the decomposition of vibrationally excited ground states of C₂H₃Cl and/or C₂H₄, in this particlar case serious consideration has to be given to alternative explanations where the products of the primary processes are formed in electronically excited states. The ±, elimination of molecular chlorine is not inconsistent with an increased degree of Cl? Cl interaction predicted for a «Rydberg «state of 1,1-C₂H₄Cl₂. Varying small yields of CH₄ are observed in the presence and absence of NO. The effect of large pressures of CF₄ on the quantum yields of the major products is extremely small. The extinction coefficient for 1,1-C₂H₄Cl₂ at 147 nm and 296°K is 246 ± 29 cm^?1 ± atm^?1.     

Synthesis of some new mono- and di-substituted o-carborane derivatives with thiolate and carbamate moieties: crystal structure of 1-(SNC5H4)-1,2-C2B10H11

Some new o-carborane derivatives of stoichiometry 1,2-(SR)₂-1,2-C₂B₁₀H₁₀ [SR=S₂NC₇H₄, S₂CNEt₂] have been synthesised by reaction of 1,2-Li₂-1,2-C₂B₁₀H₁₀ with the corresponding disulfide derivatives RSSR (RSSR=(C₇H₄NS₂)₂, 2,2′-dithiobis(benzothiazole); (Et₂NCS₂)₂, tetraethylthiuram disulfide) in molar ratio 1:2. The reaction of 1-Li-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ with RSSR (RSSR=(C₅H₄NS)₂, 2,2′-dithiodipyridine; (C₇H₄NS₂)₂) in molar ratio 1:1 has afforded the new mixed di-substituted compounds 1-SR-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ (SR=SNC₅H₄; S₂NC₇H₄). The reaction of 1-SNC₅H₄-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ with NBu₄F in THF in molar ratio 1:2 has afforded the mono-substituted derivative 1-SNC₅H₄-1,2-C₂B₁₀H₁₁, whereas the treatment of 1,2-(C₇H₄NS₂)₂-1,2-C₂B₁₀H₁₀ with NBu₄F in THF in molar ratio 1:5 has led to the partially degraded derivative NBu₄[7,8-(S₂NC₇H₄)₂-7,8-C₂B₉H₁₀]. The crystal structure of 1-SNC₅H₄-1,2-C₂B₁₀H₁₁ has been determined by X-ray diffraction.     

Aryl–Aryl Interactions in (Aryl-Perhalogenated) 1,2-Diaryldisilanes

Three 1,2-diaryltetramethyldisilanes X₅C₆-(SiMe₂)₂-C₆X₅ with two C₆H₅, C₆F₅, or C₆Cl₅ groups were studied concerning the importance of London dispersion driven interactions between their aryl groups. They were prepared from 1,2-dichlorotetramethyldisilane by salt elimination. Their structures were determined in the solid state by X-ray diffraction and for free molecules by gas electron-diffraction. The solid-state structures of the fluorinated and chlorinated derivatives are dominated by aryl–aryl interactions. Unexpectedly, Cl₅C₆-(SiMe₂)₂-C₆Cl₅ exists exclusively as an eclipsed syn-conformer in the gas phase with strongly distorted Si-C₆Cl₅ units due to strong intramolecular interactions. In contrast, F₅C₆-(SiMe₂)₂-C₆F₅ reveals weaker interactions. The contributions to the total interaction energy were analyzed by SAPT calculations.     

Determination of hydrazides and 1,2-diacylhydrazines of aliphatic carboxylic acids by conductometric titration

A procedure is developed for the conductometric titration of hydrazides and 1,2-diacylhydrazines of aliphatic carboxylic acids with HCl or KOH in nonaqueous and water-alcohol solutions. The procedure is suitable for the determination of the major substance in hydrazides of C₅H₁₁-C₁₂H₂₅ aliphatic carboxylic acids and CH₃-C₇H₁₅ 1,2-diacylhydrazines and for the analysis of reaction mixtures containing N₂H₄, RCOOH, and RCOOH · N₂H₄ along with the major substance.     

Kinetics and mechanism of the addition of trichloromethyl radicals to chloroethylenes. The addition to CIS-C2Cl2H2, trans-C2Cl2H2, and C2Cl3H

The addition reactions of CCl₃ radicals with cis-C₂Cl₂H₂, trans-C₂Cl₂H₂, and C₂Cl₃H in liquid cyclohexane–CCl₄ mixtures were studied between 323 and 448 K. The Arrhenius parameters of these reactions were competitively determined versus H-atom transfer from cyclohexane and addition to C₂Cl₄. The present data and the data obtained in previous liquid and gas phase studies show that the reactivities displayed in addition reactions of different radicals with chloroethylenes reflect primarily variations in activation energies rather than in A factors. The activation energies for the addition of CCl₃, CF₃, and CH₃ radicals to chloroethylenes appear, to a large extent, to be determinedby the stability of the adduct radicals. Comparison of the reactivity trends in the addition reactions of chloro- and fluoro-substitutedethylenes indicates that these two electron-withdrawing substituentshave a converse effect on the reactivity of electrophilic radicals. This behavior is ascribed to the strong mesomeric effect of vinylic chlorosubstituents.     

Thermodynamic interactions in rubbery polymer/gas systems

The Flory–Huggins interaction parameters χ for 23 gases (He, Ne, Ar, Kr, Xe, H₂, N₂, O₂, N₂O, CO₂, CH₄, C₂H₄, C₂H₆, C₃H₆, C₃H₈, 1,3-C₄H₆, four C₄H₈'s, n-C₄H₁₀, iso-C₄H₁₀, and n-C₅H₁₂) in five rubbery polymers (1,2-polybutadiene (PB), poly(ethylene-co-vinyl acetate)) (EVAc), polyethylene (PE), polypropylene (PP), and poly(dimethyl siloxane) (PDMS) were determined from either literature data on Henry's law coefficient and partial molar volume or those on sorptive dilation for each polymer/gas system. Values of χ for the gases increased in the order of PDMS < PP ≡ PB < EVAc ≡ PE. Among the gases except He and H₂ whose χ values are not reliable, Ne and Xe have respectively the highest and the lowest values of χ for the polyolefins. The χ values of the hydrocarbons were compared together with previously reported χ values of n-alkanes C₃-C₁₀. The dependencies of χ upon concentration and temperature were discussed on the basis of the literature data. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1049–1053, 1997     

Synthesis and studies of new organic conductors based on ET and EDT-TTF with the [ZnBr4]2− anions

New layer organic conductors based on bis(ethylenedithio)tetrathiafulvalene (ET)₄ZnBr₄Solv (Solv stands for solvent) were synthesized in various halobenzenes as solvents (C₆H₅X, X = Cl, Br, F and C₆H₄Y₂, Y = Cl, Br), as well as based on ethylenedithiotetrathiafulvalene (EDT-TTF)₄MBr₄(1,1,2-C₂H₃Cl₃) (M = Zn, Mn) and (EDT-TTF)₉(ZnBr₄)₂. The crystal structure of (ET)₄ZnBr₄(C₆H₄Cl₂) at room temperature was established. It was found to be composed of alternating conducting layers with various structure of stacks formed of the ET radical cations. Their conductivity and ESR spectra were measured. The ET compounds obtained are organic metals up to the temperatures of 4.2, 72, 80, or 183 K (depending on the solvent: C₆H₄Cl₂, C₆H₅Cl, C₆H₅Br, or C₆H₅F, respectively); the replacement of the solvent with more bulky 1,2-dibromobenzene led to the formation of a semiconductor. The compounds (EDT-TTF)₄MBr₄(C₂H₃Cl₃) with M = Zn, Mn and (EDT-TTF)₉(ZnBr₄)₂ retain metallic character of conductivity up to the temperatures of 260, 280, and 210 K.     

Oxidative addition of boron–boron, boron–chlorine and boron–bromine bonds to platinum(0)

The synthesis and spectroscopic characterisation of the new diborane(4) compounds B₂(1,2-O₂C₆Cl₄)₂ and B₂(1,2-O₂C₆Br₄)₂ are reported together with the diborane(4) bis-amine adduct [B₂(calix)(NHMe₂)₂] (calix=Bu^tcalix[4]arene). B–B bond oxidative addition reactions between the platinum(0) compound [Pt(PPh₃)₂(η-C₂H₄)] and the diborane(4) compounds B₂(1,2-S₂C₆H₄)₂, B₂(1,2-O₂C₆Cl₄)₂ and B₂(1,2-O₂C₆Br₄)₂ are also described which result in the platinum(II) bis-boryl complexes cis-[Pt(PPh₃)₂{B(1,2-S₂C₆H₄)}₂], cis-[Pt(PPh₃)₂{B(1,2-O₂C₆Cl₄)}₂] and cis-[Pt(PPh₃)₂{B(1,2-O₂C₆Br₄)}₂] respectively, the former two having been characterised by X-ray crystallography. In addition, the platinum complex [Pt(PPh₃)₂(η-C₂H₄)] reacts with XB(1,2-O₂C₆H₄) (X=Cl, Br) affording the mono-boryl complexes trans-[PtX(PPh₃)₂{B(1,2-O₂C₆H₄)}] as a result of oxidative addition of the B–X bonds to the Pt(0) centre; the chloro derivative has been characterised by X-ray crystallography.     

Transmetallation reactions involving phenylenemercurials

When heated with Group V and Group VI elements, the phenylenemercurials (C₆H₄Hg)₃, (C₆F₄Hg)₃ and (C₆Cl₄Hg)₃ form heterocycles of formulae (M₂(C₆X₄)₃ and M′₂(C₆X₄)₂ where M = As, Sb, Bi and M′ = S, Se, Te. The compounds Te₂(C₆Cl₄)₂ and M₂(C₆Cl₄)₃ (M = As, Sb, Bi) were also obtained by heating the elements with 1,2-I₂C₆Cl₄, which was prepared by mercuration of 1,2-H₂C₆Cl₄ followed by iododemercuration. Octachlorothianthrene has been obtained by heating sulphur with Te₂(C₆Cl₄)₂, C₆Cl₆ or C₆Cl₅I, and from the reaction between 1,2-H₂C₆Cl₄, AlCl₃, and S₂Cl₂.     

Double-ionization energies of fluorinated benzene molecules

Results are reported of an experimental determination by double-charge transfer spectroscopy of the previously unknown double-ionization energies of the fluorinated benzene molecules C₆H₅F, l,2-C₆H₄F₂, 1,3-C₆H₄F₂, 1,4-C₆H₄F₂, 1,2,3-C₆H₃F₃, 1,2,4-C₆H₃F₃, 1,3,5-C₆H₃F₃, 1,2,3,4-C₆H₂F₄, 1,2,3,5-C₆H₂F₄, 1,2,4,5-C₆H₂F₄, and C₆HF₅. The data are remarkably similar; the lowest double-ionization energies for all the molecules are within ±0.5 of 25.7 eV, and the data for higher energies suggest that the distributions of electronic state energies for the dications of the molecules show only small variations.     

The mechanism of ethylene pyrolysis at small conversions

Kinetic modelling is used in conjunction with measurements of product yields to develop a mechanism for the pyrolysis of ethylene at 896K and ethylene pressures ranging from approximately 3 to 78 kPa. An induction period was observed for all products except H₂, and was followed by a steady rate, which was of second-order for all products except 1,3-C₄H₆, the most abundant product. The mechanism quantitatively accounts for the yields of H₂, CH₄, C₂H₆, C₃H₆, 1-C₄H₈ and 1,3-C₄H₆. The reaction is initiated by disproportionation of C₂H₄ and the product 1,3-C₄H₆ results from decomposition of the C₄H₇ radical, formed by addition of C₂H₃ to C₂H₄. The other organic products that were measured are formed as a result of reactions involving the C₂H₅ radical. The hydrogen is produced by abstraction from C₂H₄ by atomic hydrogen and its rate is controlled by the reaction C₂H₅ → C₂H₄ + H which is nearly equilibrated. The main termination reaction is recombination of C₂H₅. The auto-acceleration which is evident particularly in the yields of H₂, CH₄, C₂ H₆, and C₃H₆ is accounted for by the decomposition of 1-C₄H₈. © 1996 John Wiley & Sons Inc.     

Highly fluorous zirconocene(IV) complexes and their catalytic applications in the polymerization of ethylene

The catalytic activities of the highly fluorous systems formed by the zirconocene(IV) complexes [Zr{η⁵-C₅H₄SiMe₂C₂H₄R_F}₂Cl₂] (R_F = C₆F₁₃ (4a), C₁₀F₂₁ (4b)) or [Zr-{η⁵-C₅H₃(SiMe₂C₂H₄C₆F₁₃)₂}₂Cl₂] (5a) and MMAO in toluene have been studied and compared with analogous nonfluorous systems generated from [Zr{η⁵-C₅H₄SiMe₃}₂Cl₂] and [Zr{η⁵-C₅H₅}₂Cl₂]. Although less active than the reference systems, the fluorous catalysts are stable over prolonged polymerization times, giving rise to polymers with similar molecular weights to those obtained with [Zr{η⁵-C₅H₄SiMe₃}₂Cl₂].