Reactivity of cis dichlorodiammineplatinum(II) (cisplatin) toward selected nucleophiles

Results are reported for the reaction of cis-dichlorodiammineplatinum(II) (“cisplatin”) with various nucleophiles in aqueous solution at constant ionic strength (μ = 0.5) and 30°C. The reactivity is described in terms of linear free energy relationships between the logarithm of the second order rate constants and two established indices of nucleophilicity, i.e. electrode potentials, E° and nucleophilic reactivity constants, n_Pt^o (based on reactivity of trans-[Pt(PY)₂Cl₂] in methanol). New nucleophilic reactivity constants, (n_Pt^o)′are reported based on “cisplatin” reactivity in water.     

Preparation of a Carbon-Coated SPME Fiber and Application to the Analysis of BTEX and Halocarbons in Water

A carbon-coated fiber for solid-phase microextraction (SPME) has been prepared from powdered activated carbon (PAC) and a fused-silica fiber. Scanning electron microscopy of the coating revealed the carbon particles were uniformly distributed on the surface of the fiber substrate. Efficient extraction of BTEX (benzene, toluene, ethylbenzene, p-xylene, and o-xylene) and halocarbons (chloroform, trichloroethylene, and carbon tetrachloride), with short extraction and desorption times, was achieved by use of the coated fiber. The maximum working temperature of the coated fiber was 300 °C and the lifetime was over 140 desorption operations at 260 °C. Limits of quantification (LOQ) of the SPME method for the eight analytes ranged from 0.01 to 0.94 μg L⁻¹, and relative standard deviations (RSD) were below 7.2% (n=6). Recoveries were 87.9–113.4% when the method was applied to the analysis of BTEX and the halocarbons in real aqueous samples. An erratum to this article is available at .     

Molecular structure of n-butane: calculation of vibrational shrinkages and an electron diffraction re-investigation

A normal coordinate analysis was carried out based on the force field of Schachtschneider and Snyder in order to calculate all amplitudes of vibration and shrinkage corrections for n-butane. The results are tabulated to aid diffraction analyses of related substances. A vapor-phase electron diffraction reinvestigation of n-butane led to experimental measurements of the principal amplitudes of vibration and to the following molecular parameters (± 3σ ): r_g(C-C) = 1.531(2)Å, r_g(C-H)= 1.117(5)Å, ∠CCC (trans. gauche average) = 113.8(4)°, ∠CCH (ave) = 111.0(5)° , gauche CCCC dihedral angle 65(6)°, % trans conformer = 54 ± 9%, and ΔG° (gauche— trans) = 497 ± 220 cal mol^?1.     

The structure of 1-chloro-1-silabicyclo(2.2.2)octane as determined by gas-phase electron diffraction

The structure of 1 -chloro-1 -si labicyclo( 2.2.2 )octane is determined by gas-phase electron diffraction. The molecule is found to have a large amplitude twisting motion with a double minimum quartic potential function of the form V(φ) = V_o[1 + (φ/φ_o)⁴ - 2(φ/φ_o)²]. Least-squares analysis of the experimental data gives values of 1.4(0.8) kcal mole^? for V_o and 17.5(2.5)° for φ_o. Other structural parameters for the “quasi-C_3v” cage-like molecule include: r_g(Si-Cl) = 2.061(3) Å, r_g(Si-C) = 1.863(3) Å, r_g(C-C_av) = 1.559(2) Å, and r_g(C-H_av) = 1.098(7) Å. Several valence angles exhibit large deviations from tetrahedral values, e.g. ∠Cl-Si-C₂ = 114.6(0.2)°, ∠Si-C₂-C₃ = 105.8(0.4)°, ∠C₂-C₃-C₄ = 114.2(1.2)°, ∠C-₃-C₄-C₅ = 111.4(0.8)° and ∠C₂-Si-C₆= 103.9(0.2)°. Many of the structural features in this strained polycyclic compound. Including the nature of the quartic potential function, can be rationalized in terms of a simple molecular mechanics model. A new method for the calculation of an analytical Jacobian of the intensity function with respect to parameters of the potential function is also discussed.     

The molecular structure of gaseous tetrachloro-p-benzoquinone and tetrachloro-o-benzoquinone by electron diffraction

The structures of tetrachloro-p-benzoquinone and tetrachloro-o-benzoquinone (p- and o-chloranil) have been investigated by gas electron diffraction. The ring distances are slightly larger and the carbonyl bonds slightly smaller than in the corresponding unsubstituted quinones. The molecules are planar to within experimental error, but small deviations from planarity such as those found for the para compound in the crystal are completely compatible with the data. Values for the geometrical parameters (r_a distances and bond angles) and for some of the more important amplitudes (l) with parenthesized uncertainties of 2σ including estimated systematic error and correlation effects are as follows. Tetrachloro-p-benzoquinone: D_2h symmetry (assumed); r(CO) = 1.216 Å(4), r(CC) = 1.353 Å(6), r(C-C) = 1.492 Å(3), r(C-Cl) = 1.701 Å(3), ∠C-C-C = 117.1° (7), ∠CC-C1 = 122.7° (2), l(CO)= 0.037 Å(5), l(CC) = l(C-C) - 0.008 Å(assumed) = 0.049 Å(7), and l(C-Cl) = 0.054 Å(3). Tetrachloro-o-benzoquinone: C_2v symmetry (assumed); r(CO) = 1.205 Å(5), r(CC) = 1.354 Å(9), r(C_cl-C_cl) = 1.478 Å(28), r(Co-C_cl) = 1.483 Å(24), r(C_o-C_o) = 1.526 Å(2), r(C-Cl)= 1.705 Å(3), <C_o-CO = 121.0° (22), ∠C-C-C = 117.2° (9), ∠C_co, ClC-Cl = 118.9° (22), ∠C_ccl, ClC-Cl = 122.2°(12), l(CO) = 0.039 Å(5), and l(C_cl-C_cl) = l(C_o-C_cl) = l( Co-Co) = l(CC) + 0.060 Å(equalities assumed) = 0.055 Å(9). Vibrational'shortenings (shrinkages) of a few of the long non-bond distances have also been measured.     

GC Analysis of Amino Acids Using Trifluoroacetylacetone and Ethyl Chloroformate as Derivatizing Reagents in Skin Samples of Psoriatic and Arsenicosis Patients

The separation and determination of 19 amino acids were examined using two stages derivatization with trifluoroacetylacetone and ethyl chloroformate from the column HP-5 (30 m × 0.32 mm id) with film thickness 0.25 ??m at an initial column temperature 100 °C for 2 min with ramping of 20 °C min^?1 up to 250 °C with nitrogen flow rate of 3 mL min^?1. The detection was performed by flame ionization detector. Total separation time was 10 min. The separation was repeatable with relative standard deviation (RSD) (n = 5) within 1.5?C1.9 and 1.3?C1.7% in terms of retention time and peak height/peak area, respectively. The method was applied for the determination of amino acids from skin samples of psoriatic patients (n = 6), arsenicosis patients (n = 5) and normal subjects (n = 9) and variation in the contents of the amino acids was noted. The RSDs for the determination were obtained within 3%.     

The structures of fluorides X. Neutron powder diffraction profile studies of UF6 at 193°K and 293°K

Neutron diffraction studies on polycrystalline UF₆ have been carried out at 193°K and 293°K. At both temperatures, UF₆ is orthorhombic with the space group Pnma (D¹⁶_2h) and Z = 4. Measured lattice parameters are a = 9.924 (10) Å, b = 8.954 (9) Å, c = 5.198 (5)Å at 293°K and a = 9.843 (11), b = 8.920 (10), c = 5.173 (6) Å at 193°K. The neutron diffraction patterns were analyzed by the least-squares profile-fitting technique. The final values of $\text{R =}\text{∑}\text{i}\text{(|I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}\text{? I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}\text{|)/∑ I}{}_{\mathrm{<mtext>o</mtext><mtext>i</mtext>}}$ over the pattern points, where I_oi is a background corrected measured intensity, were 0.081 at 193°K and 0.133 at 293°K.On cooling, the hexagonal close-packing tends to become more regular, and the FF distances external to a UF₆ octahedron contract. The octahedra are nearly regular with a mean UF distance of 1.98 Å, a mean FF edge of 2.80 Å, and a FUF angle of 90.0° at 193°K.     

Diffusion current at microdisk electrodes—application to accurate measurement of diffusion coefficients

Stationary electrodes (platinum and glassy carbon) were used for accurate measurement of diffusion coefficients. The theoretical diffusion current-time profile was calculated by digital simulation, by means of which the diffusion coefficient and the product of the charge number of electrode reaction n and the reactant concentration c^o were determined simultaneously from a single chronoamperogram. The feasibility of the method was demonstrated by measuring the diffusion coefficients of Tl(I) ions. When the nc^o value agreed with the corresponding known value, the diffusion coefficients were in good agreement with the standard values determined by the thin-walled hanging mercury drop electrode method. The diffusion coefficient of hexacyanoferrate(III) ions in 1 mol dm^?3 KCl at, 25°C was also determined.     

Étude thermodynamique de la protonation de dérivés diméthylés de la pipérazine

The thermodynamic functions ΔG^o_n, ΔH^o_n and ΔS^o_n of the two steps of proton ionization of N,N′-dimethylpiperazine, 2,6-dimethylpiperazine, 2,5-dimethylpiperazine (cis) and 2,5-dimethylpiperazine (trans) are determined at 25°C in water and water—ethanol (52%, w/w) solvents, including 0.1 M KNO₃ as ionic strength.Free energies are calculated from the ionisation constants obtained by pH-metric method; enthalpies are determined from calorimetric measurements.The comparison of these functions and of the corresponding entropies is discussed in terms of the position of CH₃ groups in each molecule and takes account of previous results relative to piperazine and its monomethyl derivatives.     

Hydrothermal synthesis and structure determination of Ag3(VVO2){O3PCH2PO3} or MIL-42: a new vanadium(V) methylendiphosphonate inserting silver cations

A new formulated compound, Ag₃(V^VO₂){O₃PCH₂PO₃} or MIL-42, was synthesized hydrothermally at 170 °C. It crystallizes in the monoclinic system (space group P2₁/n (n°14)) with lattice parameters a=8.9404(2) Å, b=8.0226(2) Å, c=11.7395(1) Å and β=100.720(1)°, V=827.32(3) ų, Z=4. Its structure was determined from single crystal X-ray diffraction data (R₁(F_o)=0.0231, wR₂(F_o²)=0.0588 for 2126 unique reflections with I≥2σ(I)). MIL-42 is three-dimensional with one-dimensional chains of corner linked trimeric units related by sheets of Ag⁺ in tetrahedral and five-fold coordination. The chains are built up from V^VO₅ trigonal bipyramids; one edge of their equatorial plane is chelated by one methylendiphosphonate group. The silver sheets are built up from corner-sharing hexamers in which silver exhibits tetrahedral and five-fold coordination.     

Synthesis and structure of bis(1,2-diaminoethane) copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-hydroxybenzoate) monohydrate and <Emphasis Type="Italic">trans</Emphasis>-diaquabis(1,2-diaminoethane)copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-aminobenzoate)

X-ray structural analysis has been performed for two complex compounds: Cu(en)₂(o-HB)₂H₂O (I) (a = 16.873(4) Å, b = 8.713(2) Å, c = 14.803(3) Å, β = 91.15(2)°, V = 2175.8(8) ų, C2/c, Z = 4, R(F) = 0.0263, 1516 reflections with I > 3σ (I)) and [Cu(en)₂(OH₂)₂]²⁺(o-AB^?)₂ (II) (a = 7.488(5) Å, b = 22.122(8) Å, c = 7.856(5) Å, β = 118.77(2)°, V = 1140.7(11) ų, P2₁/n, Z = 2, R(F) = 0.0432, 1684 reflections with I > 3σ(I)) synthesized under identical conditions (en is ethylenediamine, o-HB is o-hydroxybenzoate, and o-AB is o-aminobenzoate). Although the compounds were assumed to have similar structures and the Cu-Lig bond lengths and the cis and trans angles are acceptable for an octahedral structure, the geometric parameters of o-HB suggest that the copper atom has a plane square environment.     

Solubility of B-Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> and the Hydrolysis of Niobium(V) in Aqueous Solution as a Function of Temperature and Ionic Strength

B-Nb₂O₅ was recrystallized from commercially available oxide, and XRD analyses indicated that it is stable in contact with solutions over the pH range 0 to 9, whereas solid polyniobates such as Na₈Nb₆O₁₉?13H₂O(s) appear to predominate at pH>9. Solubilities of the crystalline B-Nb₂O₅ were determined in five NaClO₄ solutions (0.1≤I _m /mol?kg^?1≤1.0) over a wide pH range at (25.0±0.1)?°C and at 0.1 MPa. A limited number of measurements were also made at I _m =6.0 mol?kg^?1, whereas at I _m =1.0 mol?kg^?1 the full range of pH was also covered at (10, 50 and 70)?°C. The pH of these solutions was fixed using either HClO₄ (pH≤4) or NaOH (pH≥10) and determined by mass balance, whereas the pH on the molality scale was measured in buffer mixtures of acetic acid?+?acetate (4≤pH≤6), Bis-Tris (pH≈7), Tris (pH≈8) and boric acid?+?borate (pH≈9). Treatment of the solubility results indicated the presence of four species, \(\mathrm{Nb(OH)}_{n}^{5-n}\) (where n=4–7), so that the molal solubility quotients were determined according to:

$0\mathrm{.5Nb}_{2}\mathrm{O}_{5}\mathrm{(cr)+0}\mathrm{.5(2}n-5\mathrm{)H}_{2}\mathrm{O(l)}_{\leftarrow}^{\to}\mathrm{Nb(OH)}_{n}^{5-n}+(n-5)\mathrm{H}^{+}\quad (n=4\mbox{--}7)$

and were fitted empirically as a function of ionic strength and temperature, including the appropriate Debye-Hückel term. A Specific Interaction Theory (SIT) approach was also attempted. The former approach yielded the following values of log?₁₀ K _sn (infinite dilution) at 25?°C: ?(7.4±0.2) for n=4; ?(9.1±0.1) for n=5; ?(14.1±0.3) for n=6; and ?(23.9±0.6) for n=7. Given the experimental uncertainties (2σ), it is interesting to note that the effect of ionic strength only exceeded the combined uncertainties significantly in the case of log?₁₀ K _s6 to I _m =1.0 mol?kg^?1, such that these values may be of use by defining their magnitudes in other media. Values of Δ _f G ^o, Δ _f H ^o, S ^o and \(C_{p}^{\mathrm{o}}\) (298.15 K, 0.1 MPa) for each hydrolysis product were calculated and tabulated.

     

Molecular structure and conformation of gaseous chloroacetyl chloride as determined by electron diffraction

Chloroacetyl chloride is studied by gas-phase electron diffraction at nozzle-tip tempera- tures of 18, 110 and 215°C. The molecules exist as a mixture of anti and gauche confor- mers with the anti form the more stable. The composition (mole fraction) of the vapor with uncertainties estimated at 2σ is found to be 0.770 (0.070), 0.673 (0.086) and 0.572 (0.086) at 18, 110 and 215°C, respectively. These values correspond to an energy difference with estimated standard deviation ΔE^o = E^o_g -E^o_a = 1.3 ± 0.4 kcal mol^?1 and an entropy difference ΔS^o = S^o_g -S^o_a = 0.7 ± 1.1 cal mol^?1 K^?1. Certain of the diffraction results permit the evaluation of an approximate torsional potential function of the form 2V = V₁(1 - cos φ) + V₂(1 - cos 2φ) + V₃(1 - cos 3φ); the results are V₁ = 1.19 ± 0.33, V₂ = 0.56 ± 0.20 and V₃ = 0.94 ± 0.12, all in kcal mol^?1. The results for the distance (r_a), angle (_∠α) and r.m.s. amplitude parameters obtained at the three temperatures are entirely consistent. At 18°C the more important parameters are, with estimated uncertainties of 2σ, r(C-H) = 1.062(0.030) Å, r(CO) = 1.182(0.004) Å, r(C-C) = 1.521(0.009) Å. r(CO-Cl) = 1.772(0.016) Å, r(CH₂-Cl) = 1.782(0.018) Å, ∠C-C-0 = 126.9(0.9)°, ∠CH₂-CO-C1 = 110.0(0.7)°,∠CO-CH₂-C1 = 112.9(1–7)°, ∠H-C-H = 109.5° (assumed), ∠φ (gauche torsion angle relative to 0° for the anti form) = 116.4(7.7)°, δ (r.m.s. amplitude of torsional vibration in the anti conformer) == 17.5(4.2)°.     

Heat of immersion of iron(III) oxides in water at 25°C

The heat of immersion in water was measured at 25°C for three iron(III) oxides using a twin-type microcalorimeter. One of the samples was commercial α-Fe₂O₃ (sample C) and the other two (samples M and F) were prepared by calcining magnetite and iron(III) hydroxide in air at various temperatures, T_p, from 300 to 700°C. The samples were evacuated at outgassing temperature, T_o, between room temperature and 500°C at a pressure of 1 × 10^?2?2.7 × 10^?2N m^?2 for 6 h. The heat of immersion, h_i(J m^?2), of samples C and M increased with an increase in T_o and showed the maximum h_i at T_o =400°C, while sample F did not show the maximum up to T_o =500°C. The systematic correlation was not observed between h_i and T_p of sample F. The heat of reproduction of the surface hydroxyl group on sample F was approximately estimated as 6.6 × 10⁴ J mole^?1 H₂O.     

Facile synthesis of 5A zeolite from attapulgite clay for adsorption of <Emphasis Type="Italic">n</Emphasis>-paraffins

5A zeolites were facilely synthesized from attapulgite clay and sodium aluminate precursors. The optimum synthesis condition for 4A zeolite (Na-form) were H₂O/attapulgite ratio of 40:1 volume/mass, NaOH/attapulgite mass ratio of 2.35:1, the crystallization time was 4 h at 80–85 °C. The 4A zeolite was converted to related 5A zeolite (Ca-form) through ionic exchanges using calcium chloride solution with the Si/Al mole ratio of 1.3. SEM images demonstrated that as-synthesized 5A zeolites are ordered cubic crystals, average crystals length dimension is 1–2 μm. And the zeolites product had a specific surface area of 482 m² g^?1 and total pore volume of 0.274 cm³ g^?1. The static adsorption experiments showed that the equilibrium adsorption capacities of n-decane and n-pentadecane on produced 5A zeolite were 0.253 and 0.510 g g^?1, respectively. And the adsorption equilibrium time of n-decane and n-pentadecane on 5A zeolite were 45 and 60 min, respectively. The experimental adsorption data of n-decane and n-pentadecane on three zeolites could be properly fitted by the Langmuir–Freundlich isotherm model.     

Synthesis of hetero‐telechelic polymers by self‐polyaddition of monomers containing both oxetanyl and carboxyl groups

The synthesis and self‐polyaddition of new monomers, o‐, m‐, and p‐[(3‐ethyloxetane‐3‐yl)methoxyethyl]benzoic acid (o‐EOMB, m‐EOMB, and p‐EOMB) containing both oxetanyl groups and carboxyl groups were examined. The reactions of o‐EOMB, m‐EOMB, and p‐EOMB in the presence of tetraphenylphosphonium bromide as a catalyst in o‐dichlorobenzene at 150–170 °C resulted in self‐polyaddition to give the corresponding hetero‐telechelic polymers poly(o‐EOMB), poly(m‐EOMB), and poly(p‐EOMB) with M_ns = 14,500–33,400 in satisfactory yields. The M_n of poly(o‐EOMB) decreased at higher reaction temperatures than 150 °C, unlike those of poly(m‐EOMB) and poly(p‐EOMB), possibly due to inter‐ or intraester exchange side reactions. It was also found that the thermal properties and solubilities of these polymers were supposed with the proposed structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7835–7842, 2008     

The structure of the grignard reagent : IX. The crystal structure of the dimeric ethylmagnesium bromide/diisopropyl ether complex

The structure of the dimeric ethylmagnesium bromide/diisopropyl ether complex [C₂H₅MgBr - O(i-C₃H₇)₂]₂ was studied with s ingle crystal X-ray diffraction techniques. Crystals are monoclinic with spacegroup P2₁/n and two dimers per unit cell of dimensions a 7.85(1), b 14.43(2), c 11,31(2) °A, β 100.3(1)^o The structure was refined to a final R-value of 0.073. The magnesium is four coordinate; dimers are formed through bridging bromine atoms. p]This result is briefly discussed in the context of factors governing complex formation of Grignard reagents.     

Synthesis,structure, and antibacterial properties of ternary rare-earth complexes with <Emphasis Type="Italic">o</Emphasis>-methylbenzoic Acid and 1,10-phenanthroline

Ternary rare-earth complexes with o-methylbenzoic acid (o-MBA) and 1,10-phenanthroline (Phen) Ln₂(o-MBA)₆(Phen)₂ · nH₂O(n = 0, 1) (Ln = La, Pr, Y, Yb) were synthesized and characterized by elemental analysis, IR, X-ray diffraction, and TG-DTG means. The complex La₂(o-MBA)₆(Phen)₂ · H₂O (I) is composed of two species of binuclear molecules in which the La³⁺ ion is coordinated with two nitrogen atoms of Phen and seven oxygen atoms of carboxylate groups. The carboxylate groups were bonded to La³⁺ in three modes: chelating-bidentate, bridging-bidentate, and chelating-bridging tridentate. The La³⁺ ion adopted a vigorous distorted monocapped square antiprism geometry. Complex I belongs to the triclinic crystal system, P space group, lattice parameters: a = 13.058(3), b = 12.7584(11), c = 20.773(4) Å, α = 101.18(3)°, β = 93.88(3)°, γ = 115.82(3)°, V = 3283.0(11)ų, Z = 2, ρ_calcd = 1.484 mg/m³, M _r = 1467.06, F(000) = 1476, μ = 1.350 mm^-1. The structure was refined to R _l = 0.0631 and wR ₂ = 0.1504. The antibacterial activity test indicates that these complexes exhibit better antibacterial ability against Escherichia coli and Staphylococcus aureus than the corresponding rare-earth chloride or o-MBA.     

Polarography of o- and p-nitrophenyl acetic acids

Polarography of o- and p-nitrophenyl acetic acids has been carried out in aqueous buffers (pH 2.0 to 12.0) of constant ionic strength (1.0 M) at 30 ± 0.5 °C. The nitro group underwent a diffusion-controlled reduction (6e) over the whole pH range. The number of electrons involved in the reduction was found by incorporating the values of diffusion coefficients, obtained by using a McBain-Dawson cell, into the Ilkovic equation. Koutecky's method has been used to compute the kinetic parameters (αn_aand ?log k^o_f,h) for the reduction of the nitro group and a reduction mechanism is proposed.     

Preparation of highly selective zeolite ZSM-5 membranes by a post-synthetic coking treatment

Zeolite ZSM-5 membranes with high n-butane:isobutane selectivities, e.g., 322 at 185°C, are obtained by a selective deposition of coke into non-zeolitic pores. The zeolite membranes are prepared by in situ crystallization on either bare porous α-Al₂O₃ support disks or disks that are pretreated to include a diffusion barrier. The post-synthetic coking treatment is accomplished by impregnating these membranes with liquid 1,3,5-triisopropylbenzene (TIPB) for 24 h at room temperature and then calcining them in air at 500°C for 2 h. Calcination at 500°C for up to 30 h does not destroy the high n-butane:isobutane selectivity. Thermogravimetric analysis (TGA) experiments on two model pore systems ZSM-5 (5.5 Å) and Vycor glass (40–50 Å) suggest that micro-defects are selectively eliminated by the TIPB coking treatment while the intracrystalline pore space of the ZSM-5 is not affected. The elimination of non-zeolitic pores results in a large increase of n-butane:isobutane pure gas flux ratio (45 vs. 320 at 185°C) accompanied by a fourfold reduction of the n-butane flux. The permeation experiments reveal that the n-butane flux increases nonlinearly with the partial pressure in the feed while the n-butane:isobutane pure gas flux ratio remains relatively unchanged.