Kinetics and mechanism of reaction between mercuric bromoiodide and silver iodide in solid state

Kinetics and the mechanism of the reaction between mercuric bromoidide and silver iodide in solid state were studied by X-ray, chemical analysis, thermal, and electrical conductivity measurements. HgBrI and AgI react in the molar ratio 1:3 to give AgBr and Ag₂HgI₄. The data for the lateral diffusion fit best in the equation X_iⁿ = kt. It has been established that the reaction proceeds via a vapor phase diffusion-controlled mechanism through counterdiffusion of Ag⁺ and Hg²⁺. There also seems to be some evidence for the formation of solid solutions between reactant and product phases.     

Studies on the intermolecular interactions of metal chelate complexesIX: On the interaction of copper(II) dithiocarbamate with some lewis acids

The intermediate products of the reaction between copper(II) dithiocarbamate complex and some Lewis acids (HgI₂, HgBr₂, GeCl₄, AsBr₃, CoCl₂, C(NO₂)₄) as well as some organometallic compounds (SnEt₄ and PbEt₄) were studied using EPR spectroscopy. In non-polar and non-coordinating solvents HgI₂, HgBr₂ and GeCl₄ formed adducts with Cu(dtc)₂, whereas in polar and coordinating solvents the mixed-ligand complexes of the type Cu(dtc)⁺…A^?(A = HgX₃) were obtained with a complex counterion in the second coordination sphere of copper(II). With C(NO₂)₄ the intermediate reaction product in non-polar solvents was assumed to be Cu(dtc)·NO₂ which dissociates to Cu(dtc)⁺…NO₂^? in polar solvents. Similar EPR spectra were obtained with SnEt₄ and PbEt₄. The reaction of Cu(dtc)₂ with CoCl₂, AsBr₃ and SbCl₃ yielded the mixed-ligand complexes of the type Cu(dtc)X_n (n = 1 or 2) exhibiting well resolved superhyperfine splitting from one or two halogen nuclei. The influence of the medium on the above interaction is also discussed.     

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.     

原子价壳层电子量子拓扑指数与元素电负性的关系

在基态原子价壳层电子隐核图的基础上, 基于拓扑化学原理以及原子价壳层电子结构特征, 构建了原子价壳层电子量子拓扑指数(AEI), 它对基态原子实现唯一性表征, 结合原子价壳层电子平均化能(∑n_iE_i/∑n_i)等参数, 建立了一套新的元素电负性标度: X_N＝－0.588710AEI₁＋0.761214AEI₂＋0.154982(∑n_iE_i/∑n_i)－0.080929. 该式给出了周期表中氢至镅共95种元素的电负性, 结果表明新电负性标度X_N与Pauling电负性标度颇为一致. 进一步从原子价轨道量子拓扑指数确定了sp, sp², sp³杂化轨道的电负性. 新标度在元素和物质的结构-性质研究中具有一定的适用性.     

Kinetics and mechanism of solid-state reaction between cyclooctasulfur and nickel oxide

The mechanism of reaction between sulfur and nickel oxide in the solid state was studied by chemical analysis, TGA, and capillary diffusion methods. Nickel oxide and sulfur react in the molar ratio 3 : 1 to give Ni₃S₅ · 3H₂O. The data for lateral diffusion fit best in the equation ξⁿ = kt. It has been also suggested by thermal analysis that S^?2 ions are formed which are exchanged by 0^?2 ions.     

Product distribution in preparative scale electrolysis: Part VI. Competition between dimerization and first-order deactivation

The dependence of product distribution from the various experimental parameters (rates, concentration diffusion layer thickness, current density) is analyzed for a reaction scheme involving the competition between dimerization and first-order deactivation of the intermediate resulting from the first electron uptake (or removal). Two cases are considered, corresponding to the product of the first-order deactivation being either electroinactive or undergoing a further electron transfer at the electrode or in the solution. It is shown that the dimer yield is not very sensitive to the further fate of the deactivation product. It is in all cases a function of the competition parameter σ=k₁k₂^?3/2D^1/2 c⁰ δ^?1 in potentiostatic conditions and σ^Δ=k₁k₂^?3/2D^?1/2(i⁰/FS) in galvanostatic conditions (k₁, k₂ rate constants of the dimerization and deactivation reactions respectively; D diffusion coefficient; c⁰ concentration of substrate; δ diffusion layer thickness; (i⁰/S) current density). The reduction of CO₂ in DMF with competitive formation of oxalate and formate is taken as an example illustrating the theoretical analysis.     

Penning ionization and photoionization electron spectrometry of hydrogen fluoride

An electron spectrometric study has been performed on HF using metastable helium and neon atoms as well as helium and neon resonance photons. High-resolution electron spectra were obtained for a pure He(2³ S) beam, a mixed He(2¹ S, 2³ S) beam, a mixed Ne(3s,³ P ₂,³ P ₀) beam, and for HeI and NeI VUV light. From the comparison of vibrational populations of HF⁺ (X ²£ _i ,v′) and HF⁺ (A ²Σ⁺,v′) produced by He(2³ S) metastables and HeI resonance photons, we conclude that there is only a slight perturbation of the HF (X ¹Σ⁺) potential in He(2³ S) Penning ionization; no perturbation is found for HF⁺ (X ²Π _i ,v′) formation from Ne(³ P _2,0) metastable ionization of HF. For He(2¹ S)+HF theX- andA-ionic state vibrational peak shapes are substantially broader than in the He(2³ S)+HF case pointing to an additional, charge exchanged interaction (He⁺+HF^?) in the entrance channel of the former system. The vibrational population found for NeI _α photoionization of HF for formation of HF⁺ (X ²Π _i ,v′) is found to differ considerably from that for NeI _β photoionization and from the Franck-Condon factors for unperturbed HF(X ¹Σ⁺) and HF⁺ (X ²Π _i ) potentials suggesting the presence of an autoionizing superexcited state of HF in the energy vicinity of the NeI _α resonance photons. The HF⁺ (X)²Π_3/2:²Π_1/2 fine-structure branching ratios vary significantly with the ionizing agent in a similar way as previously found in HCl and HBr.     

Synthesis and asymmetric catalytic application of chiral imidazolium–phosphines derived from (1R,2R)-trans-diaminocyclohexane

Reaction between a chiral imidazole–amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P¹Cl (where P¹ = PPh₂, P(1,3,5-Me₃C₆H₃)₂, P(2,2′-O,O′-(1,1′-biphenyl), P((R)-(2,2′-O,O′-(1,1′-binaphthyl))) and P((S)-(2,2′-O,O′-(1,1′-binaphthyl)))) followed by RX (where R = ⁿPr, ⁱPr, CHPh₂, X = Br; R = ⁱPr, X = I), respectively, gives a selection of chiral imidazolium–phosphine compounds. Deprotonation of the imidazolium salt gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium catalysed transfer hydrogenation.     

Electron affinity and substituent effects in radical anions

The first vertical electron affinities EA of 13 series of molecules and free radicals D(X _i ) _n are related to the inductive (σ _I ), resonance (σ _R ^? ), and polarization (σ_α) parameters of substituents X _i by the dependences EA = EA _H + aΣσ _I + bΣσ _R/? + cΣσ_α: In radical anions D^+·(X _i ) _n , compared to radical cations D^+·(X _i ) _n , the polarization interaction is weaker or similar in magnitude but has an opposite sign. The previously unknown resonance parameters σ _R ^? of substituents SiMe₃ and CH₂SiMe₃ bound to the radical anion center H₂C=CH^?· were calculated.     

Two-photon excitation of mercury atoms by photodissociation of mercury halides

Photodissociation of HgCl₂, HgBr₂, and Hgl₂ with an ArF laser at 193 nm produces strong fluorescence from highly excited Hg atoms. The experiments indicate that single photon dissociation of the mercuric halide, HgX₂, is followed by the two-photon dissociation of HgX (X² Σ) molecules to produce electronically excited Hg atoms.     

15N- und 19F-NMR-spektroskopischer Nachweis und Xa-Austauschreaktionen der Clusteranionen [(Mo6Cl)(15NCS) X]2−, Xa = F,Cl, Br,I; n = 1–6

¹⁵N and ¹⁹F NMR Spectra and X^a-Exchange Reactions of the Cluster Anions [(Mo₆Clⁱ₈)(¹⁵NCS)^a_nX^a_6?n]^2?, X^a = F, Cl, Br, I; n = 1–6 By intermolecular ligand exchange reaction of the new compound [(Mo₆Clⁱ₈)(¹⁵NCS)^a₆] ^2? with [(Mo₆Clⁱ₆)X^a₆]^2?, X^a = F, Cl, Br, I, in acetone, the outersphere mixed cluster ions [(Mo₆Clⁱ₈)(¹⁵NCS)^a₆X^a_6?n]^2?, n = 1–6, are formed and characterized by their distinct ¹⁵N nmr chemical shifts. The ambident SCN^? is exclusively N-bonded, indicated by ¹⁵N nmr and vibrational spectra. The mixed cluster ions containing X^a = F are identified in acetonitrile by ¹⁹F nmr measurement as well. The kinetic analysis reveals equilibration at room temperature within 10 hours to statistical distribution of all compounds, inclusive the ratios for the geometric isomers for each system at any time with n = 2,4 cis:trans = 4 : 1 and n = 3 fac:mer = 2 : 3, indicating the equivalence of all X^a positions with respect to exchange reactions. For [(Mo₆Clⁱ₈)X^a₆]^2? the reaction rates increase in the series X^a = Cl < Br < I < SCN < F. The ¹⁵N nmr chemical shifts are depending on the electronegativity and the number of the X^a ligands. Furthermore an antipodal influence working on ¹⁵N trans-positioned to X^a effects an additional highfield shift for X^a = F and an additional downfield shift for X^a = Cl, Br, I.     

X-ray crystal structure and spectral characterization of pseudo five-coordinate Hg(II) polymeric and four-coordinate binuclear complexes of an ambidentate sulfonium ylide

The reaction of ambidentate sulfonium ylide (Me)₂SCHC(O)C₆H₄-p-OCH₃(Y) with HgX₂ [X = Cl (1), Br (2) and I (3)] in equimolar ratios using methanol as the solvent leads to two types of products. Single-crystal X-ray diffraction analysis reveals (i) a two-dimensional polymer, [{HgCl₂(Y)}₄]_n, in which the mercury(II) atom is five-coordinated and ligand Y displays C-coordination as well as an additional interaction, including O-coordination to different mercury centers and (ii) an asymmetric halide-bridged binuclear structure of the type [HgBr₂(Y)]₂, in which the mercury(II) center is four-coordinate and ligand Y displays C-coordination to the metal. The characterization of these compounds by IR, ¹H- and ¹³C NMR spectroscopy confirms the coordination of the ylide to the metal through the carbon atom. Analytical data indicate a 1:1 stoichiometry between the ylide and the Hg(II) halide in all complexes.     

Stability of gold(I) glycinate complexes in aqueous solution

The stepwise substitution equilibrium AuCl ₂ ^? +iX^?=AuCl_2?i X _i ^? +iCl^?, β_i, where X^? is the glycinate ion (H₂N-CH₂-COO^?), i = 1 or 2, at 25°C in an aqueous solution with I = 1.0 mol/L (NaCl) has been studied pH-metrically. The corresponding constants are logβ₁ = 3.60 ± 0.10, and logβ₂ = 6.2 ± 0.2.     

Free-radical decarboxylation of carboxylic acids as a concerted abstraction and fragmentation reaction

Two variants of the reaction of radicals with the carboxyl group of carboxylic acids, namely, RO ₂ ^? + R _i COOH → ROOH + R _i CO ₂ ^? and RO _i ^? + R _j COOH → ROOH + R _i ^? + CO₂ are theoretically analyzed. It is demonstrated by the intersecting-parabolas method that if the reaction proceeded via the formation of an intermediate carboxyl radical, it would be much slower than is actually observed. Quantum-chemical calculations carried out by the density functional method using the nonempirical functional PBE have shown that the reactions of the methyl radical with the carboxyl group of acetic, butyric and vinylacetic acids include concerted H atom abstraction and C-C bond breaking. In the framework of the intersecting-parabolas model, an algorithm has been developed to calculate the activation energy and rate constant for X^? + R _i COOH → XH + CO₂ + R _i ^? reactions, where X = R^?, RO^?, HO^?, ArO^?, Ar₂N^? or H^?     

Molecular structures and supramolecular association of chlorodiorganotin(IV) complexes with bis- and tris-dithiocarbamate ligand

Two series of di and trinuclear chlorodiorganotin(IV) complexes derived from bis- and tris-dithiocarbamate ligands have been prepared and structurally characterized. The dinuclear complexes 1-2 of the composition {(R₂SnCl)₂(bis-dtc)} (1, R = Me; 2, R = ⁿBu) have been obtained from R₂SnCl₂ (R = Me, ⁿBu) and the triethylammonium salt of N,N′-dibenzyl-1,2-ethylene-bis(dithiocarbamate). The trinuclear complexes 3-9 with the general formula {(R₂SnCl)₃(tris-dtc)} 3, R = Me, tris-dtc = tris-dtc-Me; 4, R = Me, tris-dtc = tris-dtc-ⁱPr; 5, R = Me, tris-dtc = tris-dtc-Bn; 6, R = ⁿBu, tris-dtc = tris-dtc-Me; 7, R = ⁿBu, tris-dtc = tris-dtc- ⁱPr; 8, R = ⁿBu, tris-dtc = tris-dtc-Bn; 9, R = ^tBu, tris-dtc = tris-dtc-Me) were prepared from R₂SnCl₂ (R = Me, ⁿBu, ^tBu) and the potassium dithiocarbamate salts of (tris[2-(methylamino)ethyl]amine) (tris-dtc-Me), (tris[2-(isopropylamino)ethyl]amine) (=tris-dtc-ⁱPr) and (tris[2-(benzylamino)ethyl]amine) (=tris-dtc-Bn). Compounds 1-9 have been analyzed as far as possible by elemental analysis, FAB⁺ mass spectrometry, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy, and single-crystal X-ray diffraction analysis. The solid state and solution studies showed that the dtc ligands are coordinated to the tin atoms in the anisobidentate manner. In all cases the metal centers are five-coordinate. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal coordination polyhedra with τ-values in the range of 0.32-0.53. For the members of each series characterized in the solid state by X-ray diffraction analysis, different molecular conformations were found. The crystal structures show the presence of C-H?Cl, C-H?S, C-H?π, S?Cl, S?S, Cl?Sn and S?Sn contacts.     

Asymmetric nitrogen

Reactions of the Tröger base (1) with HgBr₂ and Mel proceed with the participation of only one N atom. According to the data of X-ray diffraction analysis, the complex [(±)-1]₂·HgBr₂ crystallizes in the achiral space groupP _n . Unlike the complex [(+)-1]₂·HgBr₂, methiodide of (+)-1 in MeOH undergoes racemization at 20°C. The virtual spin-spin coupling constants⁴ J _HH observed for the base (C ₂ symmetry) are transformed into the “usual” constants in the case of the desymmetrized methiodide system.     

Anodic reactions of the halides in dimethyl sulfoxide at the pyrolytic graphite electrode

The anodic reactions of the halide ions in dimethyl sulfoxide at the pyrolytic graphite electrode have been studied. The iodide ion demonstrates a 3-step oxidation; the bromide, a 2-step oxidation and chloride, a 1-step oxidation. The electrode reaction (X^-→$\text{1}\text{2}$ X₂ + e^-) is complicated by a catalytic reaction occurring after the electrode reaction. The catalytic reaction is important for only bromide and chloride causing a considerable diffusion current enhancement. The αn_a value for all 3 primary reactions is of the order of 0.5.     

Pseudotetrahedral cobaltate(II) anions with two and three different kinds of ligands

New complexes of the general types HCo(NCS)₃ ·nL, HCoX ₂(NCS) ·nL and HCo(NCS)₂I ·nL (whereX=Cl, Br, I;L=diethyl ether, pyridine, aniline;n=1.5, 2, 3, 3.5) have been prepared and characterized. The magnetic and spectroscopic data indicate that pseudotetrahedral [Co(NCS)₃ L]^?, [CoX ₂(NCS)L]^? and [Co(NCS)₂IL]^? anions are present in the solid pyridine and aniline compounds.     

PREPARATION AND REACTIONS OF METHYLTHIOMETHYL-SUBSTITUTED PHOSPHORUS HALIDES1

Abstract

Methylthiomethylphosphonous dichloride, MeSCH₂PCI₂ (1), is synthezised by the reaction of MeSCH₂SnBuⁿ, with phosphorus trichloride. Substitution reactions to give MeSCH₂PX₂ (X=NEt₂, OPrⁱ, F, Ph) are described. The phosphorus(III) compounds are readily converted to the corresponding phosphonyl and thiophosphonyl derivatives, MeSCH₂P(Z)X₂ (Z=O, S), and the phosphorane, MeSCH₂PF₄, respectively. Chlorination of the methylene group to give compounds of the type MeSCHCIP(O)X₂ and MeSCCI₂P(O)X₂ is reported.     

Synthesis, structural characterization, and properties of heavier alkaline earth complexes containing bis(pyrazolyl)borate or bis(3,5-diisopropylpyrazolyl)borate ligands

Treatment of a solid mixture of KBH₄ with six equivalents of 3,5-diisopropylpyrazole (iPr₂pzH) at 180 °C afforded KTp^iPr2(iPr₂PzH)₃ in 53% yield. KBp^iPr2 was synthesized in 56% yield by treatment of a 1:2 M ratio of KBH₄ and iPr₂PzH in refluxing dimethylacetamide. Treatment of MI₂ (M = Ca, Sr, Ba) with two equivalents of KBp or KBp^iPr2 in tetrahydrofuran afforded MBp₂(THF)₂ (M = Ca, 64%, M = Sr, 81%), BaBp₂(THF)₄ (32%), and M(Bp^iPr2)₂(THF)₂ (M = Ca, 63%; M = Sr, 61%, M = Ba, 48%) as colorless crystalline solids upon workup. These complexes were characterized by spectral and analytical techniques and by X-ray crystal structure determinations of all complexes except KBp^iPr2. KTp^iPr2(iPr₂PzH)₃ contains one κ³-N,N,N-Tp^iPr2 ligand and three κ¹-iPr₂pzH ligands, with overall distorted octahedral geometry about the K ion. The iPr₂PzH nitrogen-hydrogen bonds are engaged in intramolecular hydrogen bonding to the 2-nitrogen atoms of the Tp^iPr2 ligand. The solid state structures of MBp₂(THF)₂, BaBp₂(THF)₄, and M(Bp^iPr2)₂(THF)₂ contain κ³-N,N,H Bp and Bp^iPr2 ligands, which form through metal-nitrogen bond formation to the 2-nitrogen atoms of the pyrazolyl fragments and metal-hydrogen bond formation to one boron-bound hydrogen atom per Bp ligand. SrBp₂(THF)₂has the shortest metal-hydrogen interactions among the series. A combination of preparative sublimations, solid state decomposition temperatures, and thermogravimetric analysis demonstrated that MBp₂(THF)₂, BaBp₂(THF)₄, and M(Bp^iPr2)₂(THF)₂ undergo solid state decomposition at moderate temperatures.