Acid–Base Properties of the \mathrm{Fe}(\mathrm{CN})_{6}^{3-}/\mathrm{Fe}(\mathrm{CN})_{6}^{4-} Redox Couple in the Presence of Various Background Mineral Acids and Salts

The acid?Cbase behavior of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ was investigated by measuring the formal potentials of the $\mathrm{Fe}(\mathrm{CN})_{6}^{3-}$ / $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ couple over a wide range of acidic and neutral solution compositions. The experimental data were fitted to a model taking into account the protonated forms of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ and using values of the activities of species in solution, calculated with a simple solution model and a series of binary data available in the literature. The fitting needed to take account of the protonated species $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ and $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ , already described in the literature, but also the species $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ (associated with the acid?Cbase equilibrium $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}\rightleftharpoons \mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-} + \mathrm{H}^{+}$ ). The acidic dissociation constants of $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ , $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ and $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ were found to be $\mathrm{p}K^{\mathrm{II}}_{1}= 3.9\pm0.1$ , $\mathrm{p}K^{\mathrm{II}}_{2} = 2.0\pm0.1$ , and $\mathrm{p}K^{\mathrm{II}}_{3} = 0.0\pm0.1$ , respectively. These constants were determined by taking into account that the activities of the species are independent of the ionic strength.     

Electrochemistry of Interaction Between Flavin Mononucleotide (FMN) and PM-17 as Antitumoral ε-Keggin Core Compound, \left[ {{\text{H}}_{ 2} {\text{Mo}}_{ 1 2}^{\text{V}} {\text{O}}_{ 2 8} \left( {\text{OH}} \right)_{ 1 2} \left( {{\text{Mo}}^{\text{VI}} {\text{O}}_{ 3} } \right)_{ 4} } \right]^{ 6- } at pH 7.5

In order to obtain a clue to the antitumor mechanism of $\left[ {{\text{Me}}_{ 3} {\text{NH}}} \right]_{ 6} \left[ {{\text{H}}_{ 2} {\text{Mo}}_{ 1 2}^{\text{V}} {\text{O}}_{ 2 8} \left( {\text{OH}} \right)_{ 1 2} \left( {{\text{Mo}}^{\text{VI}} {\text{O}}_{ 3} } \right)_{ 4} } \right]$ ·2H₂O (PM-17), the interaction of PM-17 with flavin mononucleotide (FMN) as a prosthetic group of the flavoprotein has been investigated by both polarographic analysis and isothermal titration calorimetry (ITC) technique at the physiological solution pH (7.5). The half-wave potential (?0.50 V vs. Ag/AgCl) of the d.c. polarogram for the quasi-reversible one-electron reduction of FMN was shifted by PM-17 toward a more positive potential with a resultant deviation from one-electron reduction to formally more than one-electron reduction waves. The PM-17 effect on the d.c. polarogram could be explained by a variety of FMN···(PM-17)_n (n > 0) aggregates with multiple conformations which was supported by the thermodynamic parameters (ΔH = ?29.7 kJ mol^?1, ΔS = ?28.2 J mol^?1 K^?1, ΔG = ?21.5 kJ mol^?1, and number of FMN in the binding with PM-17 (N) = 0.053 at 20 °C) estimated by the ITC technique. A large conformational change of the FMN domain by the FMN···(PM-17)_n aggregates is suggested to prevent the movement of the FMN centers into close proximity with nicotinamide adenine dinucleotide (NADH) with a resultant depression of the electron transport in NADH dehydrogenase.     

A mathematical approach to chemical equilibrium theory for gaseous systems—III: \hbox {Q}_\mathrm{p}, \hbox {Q}_\mathrm{c}, and \hbox {Q}_{\mathrm{x}}

The reaction quotient Q can be expressed in partial pressures as $\hbox {Q}_\mathrm{P}$ or in mole fractions as $\hbox {Q}_{\mathrm{x}}$ . $\hbox {Q}_\mathrm{P}$ is ostensibly more useful than $\hbox {Q}_{\mathrm{x}}$ because the related $\hbox {K}_{\mathrm{x}}$ is a constant for a chemical equilibrium in which T and P are kept constant while $\hbox {K}_{\mathrm{P}}$ is an equilibrium constant under more general conditions in which only T is constant. However, as demonstrated in this work, $\hbox {Q}_{\mathrm{x}}$ is in fact more important both theoretically and technically. The relationships between $\hbox {Q}_{\mathrm{x}}$ , $\hbox {Q}_\mathrm{P}$ , and $\hbox {Q}_{\mathrm{C}}$ are discussed. Four examples of applications are given in detail.     

Coating of $$\hbox {C}_{60}$$ by para-$$\hbox {H}_2$$H2 and ortho-$$\hbox {D}_2$$D2: revisiting the solvation shell—CMMSE

The solvation of Buckminsterfullerene \(\hbox {C}_{60}\) by para-hydrogen and ortho-deuterium clusters has been modeled using a dedicated potential and path-integral molecular dynamics simulations at low temperature (2 K). The solvation shell obtained from the distribution of radial distances is found to be complete near 50 molecules, in agreement with recent mass spectrometry measurements. Deuteration increases the shell size by one, indicating a denser shell owing to less prominent vibrational delocalization for this heavier isotope.     

Study of Complex Formation of Dibenzo-18-Crown-6 with Ce3+, Y3+, $\mathrm{UO}_{2}^{2 +}$ and Sr2+ Cations in Acetonitrile–Dioxane Binary Solvent Mixtures

The complexation reactions of dibenzo-18-crown-6 (DB18C6) with Ce³⁺, Y³⁺, UO₂^{2 +}\mathrm{UO}_{2}^{2 +} and Sr²⁺ cations were studied in acetonitrile–dioxane (AN–dioxane) binary solvent solutions at different temperatures by the conductometric method. The stability constants of the resulting 1:1 complexes were determined from computer fitting of the conductance–mole ratio data. The results show that dibenzo-18-crown-6 does not exhibit selectivity for the cation whose ionic size is closest to the cavity size of this macrocyclic ligand in AN–dioxane binary solvent solutions. A nonlinear relationship was observed between the stability constants (log ₁₀ K _f) of these complexes with the composition of the AN–dioxane binary solvent. Values of thermodynamic parameters (DH_c^°, DS_c^°\Delta H_{\mathrm{c}}^{\circ}, \Delta S_{\mathrm{c}}^{\circ}) for complexation reactions were obtained from the temperature dependence of the stability constants. The results show that the values along with the sign of these parameters are influenced by the nature and composition of the mixed solvent.     

Unimolecular reactions of \documentclass{article}\pagestyle{empty}\begin{document}$ ^ \cdot {\rm CH}_2 {\rm CH}_2 \mathop {\rm O}\limits^ + {\rm HCH}_2 {\rm CH}_2 {\rm CH}_3 $\end{document} β?distonic ion

The β-distonic ion $ ^ \cdot {\rm CH}_2 {\rm CH}_2 \mathop {\rm O}\limits^ + {\rm HCH}_2 {\rm CH}_2 {\rm CH}_3 $ has been shown previously to be an intermediate in the fragmentation of ionized ethyl propyl ether. The reactions of this ion (generated by fragmentation in the ion source of alkyl propyl ethers of glycol) were studied in this work. Labelling showed that this ion undergoes competing hydrogen transfers leading to a series of isomeric distonic ions. Each of them was submitted to an isotope effect.     

Synthesis of Calcium Phosphates by PO(OH)x(OBut)3−x and CaO2C2H4

In this work, an alkoxide solution route to synthesize Ca phosphates was developed. For the precursors, a CaO₂C₂H₄ solution was prepared by dissolving Ca metal powder into ethylene glycol, and a PO(OH)_x(OBut)_3–x solution was prepared by dissolving P₂O₅ inton -butanol under reflux conditions. In order to obtain a mixed solution of the two precursors, acetic acid was used as an additive. The experimental results show that (1) -2CaO · P₂O₅, -3CaO · P₂O₅, and hydroxyapatite can be easily synthesized by converting the corresponding mixed solutions to powder products in a hot plate, and calcining the as prepared products at 1100°C; (2) acetic acid behaves as a good agent for controlling the reactions between the two precursors by modifying the CaO₂C₂H₄ species in solution and decreasing the reactivity of the PO(OH)_x(OBut)_3–x species.     

Synthesis and Structure of Ruthenium Complexes $$\rm[{Ph_{3}PR]_2^+[RuCl_6]^{2-}}$$ (R = C2H5, CH=CHCH3, CH2CH=CHCH3, CH2OCH3), and $$\rm[{Ph_{3}PCH_2CH=CHCH_2{PPh_3}]_2^{2+}[Ru_2Cl_{10}O]^{4-}}$$[Ph3PCH2CH=CHCH2PPh3]22+[Ru2Cl10O]4−· 4H2O

Complexes \(\rm[{Ph_{3}PR]_2^+[RuCl_6]^{2-}}\), where R = C₂H₅ (I), CH=CHCH₃ (II), CH₂CH=CHCH₃ (III), and CH₂OCH₃ (IV), have been prepared by the reaction between ruthenium(III) chloride hydrate and triphenylorganylphosphonium chlorides in dimethylsulfoxide in the presence of hydrochloric acid. A hydrochloric acid solution of ruthenium(III) chloride hydrate when mixed with an aqueous solution of 2-butylene-1,4- bis(triphenylphosphonium dichloride) followed by recrystallization from dimethylsulfoxide results in complex \(\rm[{Ph_{3}PCH_2CH=CHCH_2{PPh_3}]_2^{2+}[Ru_2Cl_{10}O]^{4-}}\)· 4H₂O (V). According to X-ray diffraction data, phosphorus atoms in mono- and binuclear cations have slightly distorted tetrahedral coordination (CPC 105.54(13)°?113.00(8)°, P?C 1.758(9)?1.839(7) Å). In slightly distorted octahedral anions [RuCl₆]^2? of complexes I–IV, the Ru?Cl bond lengths vary in the range 2.3222(6)?2.340(2) Å; the cis-ClRuCl and trans-ClRuCl angles are 89.133(18)°–90.867(18)° and 179.53(13)°–180°, respectively. In the binuclear [(RuCl₅)₂O]^4? anion of complex V, RuCl₅ fragments are bonded by a bridging oxygen atom. The Ru–Cl bond lengths fall in the range 2.3375(8)?2.3957(8) Å; the Ru–O bond length is 1.7832(2) Å. The cis-ClRuCl, trans-ClRuCl, cis-ORuCl, and trans-ORuCl angles are 86.67(3)°?91.28(3)°, 174.60(3)°?174.83(3)°, 91.49(2)°?93.65(2)°, and 178.39(2)°, respectively. In crystals I–V, interionic hydrogen bonds Cl···H_cation (2.63?2.95 Å), Cl··· \({\rm{H}_{{H_2}O}}\) (2.35?2.79 Å), and H_cation···\({\rm{O}_{{H_2}O}}\) (1.72?1.93 Å) (for V) are found.     

Tris(pyrazolyl)borate half-sandwich complexes of trivalent uranium incorporating the [C8H6{SiiPr3-1,4}2]2− and [C8H4{SiiPr3-1,4}2]2− ligands

The reaction of UI₃ in THF with KTp^Me2 and the subsequent addition of [K₂(C₈H₆{SiⁱPr₃-1,4}₂)] or [K₂(C₈H₄{SiⁱPr₃-1,4}₂)] yields dark red [U(κ³-Tp^Me2)(C₈H₆{SiⁱPr₃-1,4}₂)] 1 and purple [U(κ³-Tp^Me2)(C₈H₄{SiⁱPr₃-1,4}₂)] 2, respectively. The ¹H NMR of 1 at room temperature suggests a rigid structure, whereas 2 is fluxional in solution on the NMR timescale. 1 is unreactive towards CO, CO₂ and MeNC under mild conditions; density functional calculations were used to compare the electronic and steric effects of the Tp^Me2 vs. Cp* ligands in mixed sandwich complexes of the type [U(L)(C₈H₆{SiH₃-1,4}₂)] (L = Cp* or (κ³-Tp^Me2)). On heating at 80 °C, 1 reacts with excess MeNC to yield [U(C₈H₆{SiⁱPr₃-1,4}₂)(κ²-dmpz)₂(η¹-CNMe)] 3. The structures of 1–3 have been determined by single crystal X-ray diffraction.     

Thermodynamic Model for SnO2(cr) and SnO2(am) Solubility in the Aqueous Na+–H+–OH−–Cl−–H2O System

The solubility of SnO₂(cassiterite) was studied at 23±2?°C as a function of time (7 to 49 days) and pH (0 to 14.5). Steady state concentrations were reached in <7 days. The data were interpreted using the SIT model. The data show that SnO₂(cassiterite) is the stable phase at pH values of 10 K ⁰ value of ?64.39±0.30 for the reaction (SnO₂(cassiterite) +2H₂O?Sn⁴⁺+4OH^?) and values of 1.86±0.30, ≤?0.62, ?9.20±0.34, and ?20.28±0.34 for the reaction ( $\mathrm{Sn}^{4+} + n\mathrm{H}_{2}\mathrm{O} \rightleftarrows \mathrm{Sn}(\mathrm{OH})_{n}^{4 - n} + n\mathrm{H}^{+}$ ) with values of “n” equal to 1, 4, 5, and 6 respectively. These thermodynamic hydrolysis constants were used to reinterpret the extensive literature data for SnO₂(am) solubility, which provided a log?₁₀ K ⁰ value of ?61.80±0.29 for the reaction (SnO₂(am)+2H₂O?Sn⁴⁺+4OH^?). SnO₂(cassiterite) is unstable under highly alkaline conditions (NaOH concentrations >0.003 mol?dm^?3) and transforms to a double salt of SnO₂ and NaOH. Although additional well-focused studies will be required for confirmation, the experimental data in the highly alkaline region (0.003 to 3.5 mol?dm^?3 NaOH) can be well described with log?₁₀ K ⁰ of ?5.29±0.35 for the reaction Na₂Sn(OH)₆(s)?Na₂Sn(OH)₆(aq).     

新型杂多化合物[(CH3CH2)4N]4H3O· {Na[(HMo2O5)3(HPO4)(H2PO4)3]2}·(H2PO4)2·10H2O的水热合成与晶体结构

杂多化合物在催化、医药、材料及光化学等方面具有广泛的应用前景 [1～ 4 ] ,其中钼磷多金属氧酸盐具有优异的氧化催化性能 [5,6 ] .近年来合成的新奇结构的钼磷多金属氧酸盐中已测定结构的有含帽[7,8] 和非帽[9～ 12 ] 系列 .本文利用水热法合成了未见文献报道的结构新颖的夹心型磷钼多金属氧酸盐[( CH3CH2 ) 4N]4 H3O{Na[( HMo2 O5) 3( HPO4 ) ( H2 PO4 ) 3]2 }· ( H2 PO4 ) 2 · 1 0 H2 O,并测定了其晶体结构 .1　实验与晶体结构分析1 .1　仪器与试剂　元素 Na用美国原子吸收分光光度计测定 ;C,H和 N用 Perkin- Elmer 2 4 0…     

CRYSTAL STRUCTURE OF {Mo_3(μ_3-S)(μ-S)_3 [S_2P(OEt}_2]_4·PhCH_2CN}

<正> Mr=2548.12, Triclinic, P1, a=15.941(5), b=15.957(2),c=20.240(6)A, α=76.41(2),β=83.87(2),γ=74.41(2)°,V=4814.6A3, Z=4, Dc=1.757g.cm-3, Final R=0.053 for 11867 reflections. There are two crystallographically independent M1 type trinuclear Mo cluster molecules with 'loose coordination site', A and B, in an asymmetric unit of the title crystal. They are formulated as {Mo3S4(u-dtp)(dtp)3.PhCH2CN}(dtp=[S2P(OEt)2]-) and have essentially identical cluster molecular configuration, but differ from each other in the conformations for the phenyl rings of the ligands PhCH2CN. The lengths of the Mo-Mo bonds are 2.750(1), 2.753(1),and 2.768(1)A for molecule A and 2.742(1), 2.756(1), and 2.764(1)A for molecule B, while the dihedral angles betweem the phenyl ring and the {Mo3} triangle are 25.0° and 94.9° for A and B respectively.     

Synthesis and Crystal Structure of a Novel Heptanuclear Ruthenium- and Sodium-containing Polyoxomolybdate [{Na(H_2O)_3}_2{Ru(dmso)_3}_2(MoO_4)_3]·_3H_2O

1 INTRODUCTION Polyoxomolybdates have been of great interest due to their unique structural varieties, associated multitude of properties and applications as catalysis, medicine and material[1, 2]. One of the most impor- tant aspects is the synthesis and investigation of the materials on polyoxomolybdates containing organo- metallic groups[3～5]. Such materials can provide molecular models for heterogeneous catalysis and display cooperative effects or bifunctional catalytic activity[6]. O…     

(2)(∞)[Co{1,4-C6H4(CN)2}2{NTf2}2][SnI{Co(CO)4}3](2)--a 2D coordination network with an intercalated carbonyl cluster

Dark red transparent crystals of [Co{1,4-C(6)H(4)(CN)(2)}(2){NTf(2)}(2)][SnI{Co(CO)(4)}(3)](2) are obtained by reacting SnI(4), Co(2)(CO)(8) and 1,4-C(6)H(4)(CN)(2) in the ionic liquid [EMIm][NTf(2)] (EMIm: 1-ethyl-3-methylimidazolium; NTf(2): bis(trifluoromethylsulfonyl)imide). According to X-ray structure analysis based on single crystals, the title compound crystallizes in a triclinic manner and contains the novel (2)(∞)[Co{1,4-C(6)H(4)(CN)(2)}(2){NTf(2)}(2)] coordination network. This infinite 2D network is composed of Co(2+) ions that are planarily interlinked by four 1,4-dicyanobenzene ligands. As a non-charged 2D network, Co(2+) is furthermore coordinated by two [NTf(2)](-) anions. The (2)(∞)[Co{1,4-C(6)H(4)(CN)(2)}(2){NTf(2)}(2)] layers are stacked on top of each other with SnI[Co(CO)(4)](3) molecules intercalated in distorted cubic gaps between the layers. The title compound is furthermore characterized by energy dispersive X-ray (EDX) analysis, thermogravimetry (TG), infrared spectroscopy (FT-IR) and optical spectroscopy (UV-Vis).     

Bis[tetraruthenium(IV)]-containing polyoxometalates: [{Ru(IV)4O6(H2O)9}2Sb2W20O68(OH)2]4- and [{Ru(IV)4O6(H2O)9}2{Fe(H2O)2}2{β-TeW9O33}2H]-

The reaction of [Sb(2)W(22)O(74)(OH)(2)](12-) and [Fe(4)(H(2)O)(10)(β-TeW(9)O(33))(2)](4-) with (NH(4))(2)[RuCl(6)] in aqueous solution resulted in the novel ruthenium(IV)-containing polyanions [{Ru(IV)(4)O(6)(H(2)O)(9)}(2)Sb(2)W(20)O(68)(OH)(2)](4-) and [{Ru(IV)(4)O(6)(H(2)O)(9)}(2){Fe(H(2)O)(2)}(2){β-TeW(9)O(33)}(2)H](-), exhibiting two cationic, adamantane-like, tetraruthenium(IV) units {Ru(4)O(6)(H(2)O)(9)}(4+) bound to the respective polyanion in an external, highly accessible fashion.     

SYNTHESIS AND STRUCTURE OF SALTS OF THE N,N′,N″-TRIS(4-(PHENYLDIAZENYL)PHENYL) IMIDOSULFITE ANION – AN ORGANIC ANALOGUE OF $$\mathbf{SO}_{\mathbf{3}}^{\mathbf{2}-}$$

Journal of Structural Chemistry - Reduction of 4,4′-bis-(phenyl azo)-diphenyl thiodiimide S(=N–C6H4–N=N–C6H5)2 (1) in tetrahydrofuran (ТHF) with potassium-intercalated...     

Direct chemiluminescence determination of fenbufen by the enhancement of the {\text{Ru}}\left( {{\text{phen}}} \right)_3^{2 + } –cerium(IV) system

A method is described for determination of fenbufen that is based on the chemiluminescence (CL) reaction of the ${\text{Ru}}\left( {{\text{phen}}} \right)_3^{2 + } $ –cerium(IV)–fenbufen system. An enhanced CL reaction was developed, and optimum conditions for CL were investigated. The CL was linearly dependent on fenbufen concentration in the range 4.0?×?10^?8–9.0?×?10^?6 mol L^?1. The detection limit was 2.0?×?10^?8 mol L^?1. The relative standard deviation (RSD) was 2.8% for eleven measurements of 6.0?×?10^?7 mol L^?1 fenbufen standard solution. The new method enables simple, sensitive, and rapid determination of fenbufen and has been used for determination of fenbufen in pharmaceutical preparations in capsule, spiked serum and urine samples.     

Bismuth(Ⅲ) Complexes with N,N-Di(2-hydroxylethyl)amino-dithiocarboxylate: Synthesis and Crystal Structure of {Bi[S_2CN(C_2H_4OH)_2]_2[1,10-Phen]_2(NO_3)}·3H_2O and {Bi[S_2CN(C_2H_4OH)_2]_3}_2

Introduction The chemistry of organotin(IV) dithiocarbamate complexes was extensively studied due to their biological activities.1-5 To date, a large number of transition-metal complexes with dithiocarbamate have been synthesized and structurally characterized,6-9 including Ni(S2CNC4H8O)2, Cu(S2CNC4H8)2, Zn(S2CNC4H8O)2 and Fe(S2CNC4H8O)2(DMF). However, the chemistry of main-group metal complexes with dithiocarbamate has been scarcely studied, and few reports have appeared on the s…     

{Cu[H_2NC(CH_2OH)_3]_2}{Pic}_2·H_2O的合成与晶体结构

三羟甲基氨基甲烷与苦味酸(Pic)铜在乙醇水混合液中反应,制得少见的不对称氢键连接的超分子化合物{Cu[H2NC(CH2OH)3]2}{Pic}2?H2O。晶体属三斜晶系,空间群为P ,晶胞参数为a = 6.894(1),b = 8.219(1),c = 13.543(3) ? ?= 79.290(1),?= 8 3.36(2), ?= 84.590(1)埃轿狢20H30CuN8O22,V = 746.9(2) 3,Z = 1,Dc = 1.774 g/cm3,F(000) = 411,?= 0.844 mm-1,R = 0.0334,Rw = 0.0863。在配合物的结构单元中, Cu2+位于对称中心,分别与2个四齿配体(三羟甲基氨基甲烷)中的2个OH,1个NH2,三齿配位,呈笼状螯合。而另一个OH,因配体和中心离子构型的限制,不参与配位。     

Phase equilibria in the system Rb3PO4–Ba3(PO4)2

The system Rb₃PO₄–Ba₃(PO₄)₂ was investigated by thermoanalytical methods, X-ray powder diffraction, ICP, and FT-IR. On the basis of the obtained results its phase diagram was proposed. For this system with one intermediate compound, BaRbPO₄, we found that this compound melts congruently at 1700 °C, exhibits a polymorphic transition at 1195 °C and is high-temperature unstable. Also, the intermediate compound was subject to gradual decomposes to Ba₃(PO₄)₂ (the solid phase) and vaporization (with conversion of phosphorus and rubidium oxides into vapor phase). We also found that Rb₃PO₄ melts congruently at 1450 °C and shows a polymorphic transition at 1040 °C. Regarding Ba₃(PO₄)₂, we have confirmed that it melts congruently at 1605 °C and exhibits a polymorphic transition at 1360 °C.