Catalytic [2+2]-cycloaddition of 3,3-disubstituted cyclopropenes to norbornene and norbornadiene

Conclusions 3,3-Dialkyl(cycloalkyl)cyclopropenes react with norbornene and norbornadiene at –20°C in the presence of complexes of CuCl with (PhO)₃P or Ph₃P exclusively by [2 + 2]-cycloaddition, giving the corresponding exo,trans-tetracyclo[5.2.1.0^2,6.0^3,5]decanes (or decenes) in yields of 60–94%, the tricyclohexane cyclodimers being obtained in yields of 5–25%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1534–1540, July, 1987.     

Kinetics of base hydrolysis of trans-{Cr([15]aneN4)Cl2}+ ([15]aneN4 = 1,4,8,12-tetra-azacyclopentadecane)

Summary Reaction of CrCl₃(DMF)₃ with [15]aneN₄ (L; L = 1,4,8,12-tetra-azacyclopentadecane) gives the green trans-{Cr([15]-aneN ₄)Cl₂}Cl in high yield. The base hydrolysis kinetics of the cations [CrLCl₂]⁺ and [CrLCl(OH)] ⁺ have been investigated over a temperature range. For the dichloro complex, k _OH = 1.03 dm³ mol^–1 s^–1] at 25° C with H =30.4 kJmol^–1 and S _inf298 ^sup = -143 JK^–1 mol^–1. The substantial negative entropy of activation implies more association of water in the loss of Cl^– from the conjugate base in a D_CB mechanism. The kinetic parameters for the chlorohydroxo complex are k _OH = 1.9 × 10^–2dm³mol^–1 s^–1 at 25°C with H = 78.3kJmol^–1 and H _inf298 ^sup = -15 J K^–1 mol ^–1. The chlorohydroxo complex probably has the trans VI configuration with the chloride ligand on the same side of the equatorial plane as the four chiral sec-NH groups. The visible spectra of a variety of complexes trans-[Cr(L)XY] ⁿ⁺ (X = Y = Cl, OH, OH₂; X = Cl, Y = OH) have been determined.     

Reaction of diazoalkanes with unsaturated compounds. Report 4. Cyclopropanation of vinyl- and allylhalides with diazomethane in the presence of copper (I) chloride and triphenylphosphite

Conclusions Reaction of vinylhalides (vinylbromide, 1-chloro-1-cyclopropylethylenes) with CH₂N₂ in the presence of (PhO)₃P·CuCl leads to formation of the corresponding halocyclopropanes with 13–15% yields, while reaction of CH₈N₂ with alkylbromide under the same conditions gives the product of formal methylene introduction, 4-bromobut-1-ene (yield 58%) with insignificant formation (1%) of bromomethylcyclopropane.For Report 3 see [1].Translated from Izvestiya Akademii Nauk SSSR, Vol. 23, No. 1, pp. 135–138, January, 1987.     

Multinuclear macromolecule metal complexes 2. Preparation and characterization of Prussian blue and its analogs bonded to pofy(vinylamine hydrochloride)

Prussian blue and its analogs bonded to poly(vinylamine hydrochloride) (PVAm · HCl) containing Fe^II or Fe^III and M²⁺ (M=Fe, Co, Cu) in a 11 molar ratio were obtained by the reaction of [Fe(CN)₆] ^n– (n=3,4) with M²⁺ ion-PVAm · HCl mixture in aqueous solution. Under a limited polymer concentration (T_VAm/T_Fe over 10), these polymer complexes thus obtained were stable and soluble in water. By casting these solutions, colored films can be produced. The formation of Prussian blue and its analogs bonded to PVAm · HCl was also investigated by the Benesi-Hildebrand method. The molar extinction coefficients of intervalence charge transfer (Fe^IIFe^III, Co^IIFe^III, Fe^IICu^II) band for MFe(CN)₆]^(n–2)– bound to PVAm · HCl (M=Fe, Co, Cu) were found to be 10,100–9601 · mol^–1 · cm^–1 at 25 C. The formation constants were found to be in the range of 10⁷ to 10¹⁰ M^–1. The changes of enthalpy (H) and entropy (S) were found to be in the range of –10.4 to –22.5 kJ · mol^–1 and 5.7 to 52.9 J · K^–1 mol^–1 respectively, at 25C.     

Hydrolysis of [Pt(dien)H2O]2+ and [Pd(dien)H2O]2+ complexes in water

The hydrolysis of the [Pt(dien)H₂O]²⁺ and [Pd(dien)H₂O]²⁺ complexes has been investigated by potentiometry at 298 K, in 0.1 mol dm^–3 aqueous NaClO₄. Least-squares treatment of the data obtained indicates the formation of mononuclear and -hydroxo-bridged dinuclear complexes with stability constants: log ₁₁ = –6.94 for [Pt(dien)OH]⁺, log ₁₁ = –7.16 for [Pd(dien)OH]⁺, and also log ₂₂ = –9.37 for [Pt₂(dien)₂(OH)₂]²⁺ and log ₂₂ = –10.56 for [Pd₂(dien)₂(OH)₂]²⁺. At pH values > 5.5, formation of the dimer becomes significant for the Pt^II complex, and at pH > 6.5 for the Pd^II complex. These results have been analyzed in relation to the antitumor activity of Pt^II complexes.     

Metal ion catalysed aquation of carboxylatoamine cobalt(III) complexes. Kinetics of copper(II) catalysed aquation ofcis(diformato)bis(ethylenediamine)cobalt(III) ion

Summary The aquation ofcis-[(en)₂Co(CO₂H)₂]⁺ tocis-[(en)₂Co(OH₂)(CO₂H)]²⁺ is catalysed by Cu²⁺ and the rate equation, –d[complex]_t/dt=(k_Cu[Cu²⁺]+k_H [H⁺]) [complex)_T is valid at [Cu²⁺]_T=0.01–0.1, I=0.5 and [HClO₄]=0.005 mol dm^–3. The rate measurements are reported at 30, 35, 40 and 45°C and the rate and activation parameters for the Cu²⁺ and H⁺-catalysed paths are: k_H(35°C)=(2.44±0.09)×10^–2 dm³ mol^–1 s^–1, H=83±13 kJ mol^–1, S=–8±42 JK^–1 mol^–1, k _Cu (35°C)=(3.30±0.09)×10^–3 dm³ mol^–1 s^–1, H=73.2±6.1 kJ mol^–1, S=–55±20 JK^–1 mol^–1. The formate-bridged innersphere binuclear complex,cis-[(en)₂Co{(O₂CH)₂Cu}]³⁺ may be involved as the catalytically active intermediate in the copper(II)-catalysed path, just as the corresponding H⁺-bridged species presumed to be present in the acidcatalysed path.     

Kinetic and EPR studies on radical polymerization. Radical polymerization of di-2[2-(2-methoxyethoxy)ethoxy]ethyl itaconate

The polymerization of di-2[2-(2-methoxyethoxy)ethoxy]ethyl itaconate (1) with dimethyl 2,2-azobisisobutyrate (2) was studied, in benzene, kinetically and spectroscopically with the electron paramagnetic resonance (EPR) method. The polymerization rate (R _p) at 50°C is given by the equation:R _p=k[2]^0.48 [1]^2.4. The overall activation energy of polymerization was calculated to be 34 kJ·mol^–1. From an EPR study, the polymerization system was found to involve EPR-observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (k _p) and termination (k _t) were determined. With increasing monomer concentration,k _p(1.54.3 L·mol^–1·s^–1 at 50°C) increases andk _t (1.0·10⁴4.2·10⁴ L·mol^–1·s^–1 at 50°C) decreases, which seems responsible for the high dependence ofR _p on the monomer concentration. The activation energies of propagation and termination were calculated to be 11 kJ·mol^–1 and 84 kJ·mol^–1, respectively. For the copolymerization of 1(M ₁) and styrene (M ₂) at 50°C in benzene the following copolymerization parameters were found:r ₁=0.2,r ₂=0.53, Q₁=0.57, ande ₁=+0.7.     

Crystal Structure of 4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Semihydrate Oxonium Tribromide

The crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo-[8.8.8]hexacosane semihydrate oxonium tribromide, [H₂(2.2.2-Crypt)·0.55H₂O]²⁺·H₃O⁺·3Br⁻ (I) was determined by XRD analysis. The triclinic structure of I (space group P , a = 10.026 Å, b = 11.292 Å, c = 13.115 Å, α = 78.37°, β = 72.11°, γ = 77.50°, Z = 2) was solved by direct methods; full-matrix least-squares refinement in an anisotropic approximation converged to R = 0.055 for all 4057 independent reflections collected (CAD-4 automatic diffractometer, λCuK _α).Original Russian Text Copyright © 2004 by A. N. Chekhlov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1136–1141, November–December, 2004.     

The kinetics and mechanism of aquation and base hydrolysis of the cis-[Co(cyclen)Cl2]+ cation (cyclen=1,4,7,10-tetraazacyclododecane)

The aquation of cis-[Co(cyclen)Cl2]+ (cyclen=1,4,7,10-tetraazacyclododecane) has been studied over a range of temperatures with 0.1 mol dm–3 HNO3 as solvent. At 25°C, kaq=4.5×10–3 s–1 with H=78 kJ mol–1 and S298=–21 J K–1 mol–1. Base hydrolysis of cis-[Co(cyclen)Cl2]+ is extremely rapid with kOH=2.1×107 dm3 mol–1 s–1 at 25°C and I=0.1 mol dm–3. This is the largest rate constant so far reported for the base hydrolysis of a cis-dichloro-complex of a saturated macrocycle. The activation parameters, H=53 kJ mol–1 and S298=73 J K–1 mol–1 are consistent with a mechanism in which deprotonation of the substrate is rate-determining. This conclusion is confirmed by the observation of general base catalysis by formate ion. The Brønsted value for the reaction is ca. 0.72 and SN1(CB) and E2 mechanisms are considered to account for the kinetic results. Base hydrolysis of cis-[Co(cyclen)(OH)Cl]+ has also been studied in the pH range 6.5 to 8.7. The value of kOH=3.8×102 dm3 mol–1 s–1 at 25°C and I=0.1 mol dm–3 with H=110 kJ mol–1 and S298=171 J K–1 mol–1 are consistent with an SN1(CB) mechanism.     

Highly stable pseudo[2]rotaxanes co-driven by crown ether-ammonium and donor-acceptor interactions

Bis-p-phenylene-34-crown-10 derivatives 1 and 2, bearing one and two dibenzo[24]crown-8 units, respectively, and 4,4′-dipyridinium derivatives of 3·3PF₆ and of 4·4PF₆, bearing one and two ammonium groups, respectively, have been synthesized from readily available starting materials. ¹H NMR and UV-vis studies reveal that in polar acetonitrile 1 binds 3·3PF₆ to produce pseudo[2]rotaxane 1·3·3PF₆ by making use of one donor-acceptor and one electrostatic interaction, whereas 2 binds 4·4PF₆ to form pseudo[2]rotaxane 2·4·4PF₆ through one donor-acceptor and two electrostatic interactions. The association constants of the two pseudorotaxanes have been determined by the UV-vis titration method to be 9.1 (±1.0)×10³ M⁻¹ and 6.5 (±0.7)×10⁵ M⁻¹, respectively. The high stability of the new pseudo[2]rotaxanes has been ascribed to the cooperative interaction of the two different non-covalent forces.     

On the mechanism of racemisation of dichlorobis(ethylenediamine)-metal chlorides [metal = cobalt(III) or chromium(III)] in the solid state

Summary In the solid state l-cis-[M(en)₂Cl₂]Cl [M=cobalt(III) or chromium(III)] undergoes thermal racemisation smoothly at 158 °C without anycis-trans interconversion. The values of k_rac, H and S are 6 × 10^–6s^–1, 218 kJM^–1 and 156.1 JK^–1M^–1 for the cobalt(III) complex and 3.5 × 10^–5s^–1, 229.7 kJM^–1 and 197.9 JK^–1M^–1 for the chromium(III) complex, respectively. The results are only in accord with a rhombic twist mechanism of the type originally proposed by Ray and Dutt for [M(AA)₃] complexes.     

Yield ratio of [11C]-CO2, [11C]-CO and [11C]-CH4 from the irradiation of N2/H2-mixtures in a gas target

The¹⁴N/p, /¹¹C-reaction was studied in different N₂/H₂-mixtures. The products are [¹¹C]-CO₂, [¹¹C]-CO and [¹¹C]-CH₄. The yield ratio may be controlled by varying the bombardment conditions. High pressure, high H₂-content, high beam current and high proton energy shift the ratio towards [¹¹C]-CH₄. Lower beam current and lower proton energy increase the yield of [¹¹C]-CO₂. The production of [¹¹C]-CO is constant over a wide range of conditions /about 10%/. For the production of [¹¹C]-CH₄ in good yield a target gas holder for high pressures has been developed. Details are given in Fig. 7. This target gas holder was filled with 5% H₂ in N₂ at 3×10⁶ Pa. Proton irradiation of the mixture gives a typical yield of [¹¹C]-CH₄ of 400–500 mCi at a beam current of 15–20 A within 20 min. Only traces of other¹¹C-labelled compounds could be detected under these conditions.     

Crystal Structure of 4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Triaquachlorolithium Dichloride

The crystal adduct (1 :1) 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane triaquachlorolithium dichloride, [H₂(Crypt-222)]²⁺ · 2Cl^– · [LiCl(H₂O)₃] (I), was synthesized and studied using X-ray diffraction analysis. Structure I (space group R3, a = 7.922 Å, c = 37.207 Å, Z = 3) was solved by direct methods and anisotropically refined by the full-matrix least-squares method to R = 0.034 for 1363 independent reflections (CAD4 autodiffractometer, MoK ). Crystal I consists of disordered 2.2.2-cryptand dications, chloride anions, and tetrahedral [LiCl(H₂O)₃] complexes. All of them lie on threefold axes. There are tridentate ⁺N–H (···O)₃ hydrogen bonds in the [H₂(Crypt-222)]²⁺ dication. The crystal structure of adduct I contains a complex interionic hydrogen bonding system.     

Effect of the chemical nature of the support on the properties of platinum catalysts for the combined oxidation of CO and H2

The steady-state rate of hydrogen oxidation catalyzed by platinum on an inert support (corundum) is greater than the rate of oxidation of carbon monoxide, while the rate of hydrogen oxidation on a platinum-vanadium catalyst is less than the rate of oxidation of carbon monoxide. The conditions for the complete selective oxidation of the reaction mixture components were determined. Hydrogen is oxidized on the Pt/corundum cataljst at 273K in a non-steady-state mode, while CO is oxidized on the same catalyst at 273 K and on Pt/BaSO₄-V₂O₅ at 383–393K in a steady-state mode.Deceased.Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 31, No. 2, pp. 81–85, March–April, 1995.     

Die Kristallstruktur von Ge5O[PO4]6

Zusammenfassung Die Kristallstruktur der Verbindung Ge₅O[PO₄]₆ wurde auf Grund dreidimensionaler Einkristalldaten ausWeissenberg-Aufnahmen ermittelt und nach der Methode der kleinsten Quadrate verfeinert: Raumgruppe ;a=7,994±0,004 undc=24,87±0,01 Å;Z=3; 467 unabhängige Reflexe;R=0,086.Die Kristallstruktur wird aus singulären [GeO₆]-Oktaedern und [Ge₂O₇]-Doppeltetraedern aufgebaut, die über [PO₄]-Tetraeder zu einem dreidimensionalen Strukturverband vernetzt sind. Die mittleren Abstände betragen: Ge^[6]–O=1,863, Ge^[4]–O=1,704 und P–O=1,525 Å.

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The crystal structure of Ge₅O[PO₄]₆

The crystal structure of Ge₅O[PO₄]₆ has been determined and refined by least-squares, using three-dimensional x-ray data fromWeissenberg-photographs: space group ;a=7.994±0.004 andc=24.87±0.01 Å;Z=3; 467 independent reflections;R=0.086.The crystal structure consists of isolated [GeO₆] octahedra and [Ge₂O₇] double tetrahedra which are linked by [PO₄] groups forming a three-dimensional network. The average interatomic distances are: Ge^[6]–O=1.863, Ge^[4]–O=1.704 and P–O=1.525 Å.

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Mit 2 Abbildungen     

Synthesis,crystal structure and magnetic properties of a two-dimensional mixed-valence assembly [Fe(salen)]2[Fe(CN)5NO]

A cyanide-bridged Fe^III–Fe^II mixed-valence assembly, [Fe^III(salen)]₂[Fe^II(CN)₅NO] [salen = N,N-ethylenebis(salicylideneiminato)dianion], prepared by slow diffusion of an aqueous solution of Na₂[Fe(CN)₅NO] · 2H₂O and a MeOH solution of [Fe(salen)NO₃] in an H tube, has been characterized by X-ray structure analysis, i.r. spectra and magnetic measurements. The product assumes a two-dimensional network structure consisting of pillow-like octanuclear [—Fe^II—CN—Fe^III—NC—]₄ units with dimensions: Fe^II—C = 1.942(7) Å, C—N = 1.139(9) Å, Fe^III—N = 2.173(6) Å, Fe^II—C—N = 178.0(6)°, Fe^III—N—C = 163.4(6)°. The Fe^II—N—O bond angle is linear (180.0°). The variable temperature magnetic susceptibility, measured in the 4.8–300 K range, indicates the presence of a weak intralayer antiferromagnetic interaction and gives an Fe^III–Fe^III exchange integral of –0.033 cm^–1.     

Kinetics and mechanism of the interaction of azide with [(H2O)(tap)2RuORu(tap)2-(H2O)]2+ ion at physiological pH

The title reaction has been studied spectrophotometrically in aqueous medium as a function of [substrate complex], [ligand], pH and temperature at constant ionic strength. At the physiological pH (7.4) the interaction with azide shows two distinct consecutive steps, i.e., it shows a non-linear dependence on the concentration of N₃ ^–; both processes are [ligand]-dependent. The rate constant for the processes are: k ₁10^–3 s^–1 and k ₂10^–5 s^–1. The activation parameters calculated from Eyring plots are: H ₁ = 14.8 ± 1 kJ mol^–1, S ₁ = –240 ± 3 J K^–1 mol^–1, H ₂ = 44.0 ± 1.5 kJ mol^–1 and S ₂ = –190 ± 4 J K^–1 mol^–1. Based on the kinetic and activation parameters an associative interchange mechanism is proposed for the interaction process. From the temperature dependence of the outersphere association equilibrium constant, the thermodynamic parameters calculated are: H ₁ ⁰ = 4.4 ± 0.9 kJ mol^–1, S ₁ ⁰ = 64 ± 3 J K^–1 mol^–1 and H ₂ ⁰ = 14.2 ± 2.9 kJ mol^–1, S ₂ ⁰ = 90 ± 9 J K^–1 mol^–1, which gives a negative G ⁰ value at all temperatures studied, supporting the spontaneous formation of an outersphere association complex.