Solvent extraction of lanthanide ions with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP)

The solvent extraction of Er(III), Yb(III) and Lu(III) by 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP or HL) in carbon tetrachloride has been studied as a function of thepH of the aqueous phase and the concentration of the extractant in the organic phase. The equation for the extraction reaction has been suggested as: $$Ln^{3 + } + 3HL_{(0)} \rightleftharpoons LnL_{3(0)} + 3H^ + \left( {Ln^{3 + } = Er,Yb, Lu} \right)$$ The extraction equilibrium constants (K _ex ) and two-phase stability constants (β ₃ ^x ) for theLnL ₃ complexes have been evaluated.     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

Extraction of lutetium(III) and erbium(III) with 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous solutions was examined. The composition of the complex extracted was determined and it was found that the extraction process can be described by the following equation (Ln ³⁺=Lu, Er): $$Ln(H_2 O)_m^{3 + } + 3 HL_{(0)} \mathop \rightleftharpoons \limits^{K_{ex} } LnL_{3(0)} + 3 H^ + + mH_2 O$$ The extraction constants (K _ex ) and two-phase stability constants (β ₃ ^x ) forLnL ₃ complexes have been evaluated.     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The solvent extraction of Yb(III) and Ho(III) by 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous-methanol phase has been studied as a function ofpH ^× and the concentration ofPAN or methanol (MeOH) in the organic phase. When the aqueous phase contains above ～25%v/v of methanol the synergistic effect was increased. The equation for the extraction reaction has been suggested as: $$\begin{gathered} Ln(H_2 0)_{m(p)}^{3 + } + 3 HL_{(o)} + t MeOH_{(o)} \mathop \rightleftharpoons \limits^{K_{ex} } \hfill \\ LnL_3 (MeOH)_{t(o)} + 3 H_{(p)}^ + + m H_2 0 \hfill \\ \end{gathered} $$ where:Ln ³⁺=Yb, Ho; $$\begin{gathered} t = 3 for C_{MeOH in.} \varepsilon \left( { \sim 25 - 50} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon }; \hfill \\ t = 0 for C_{MeOH in.} \varepsilon \left( { \sim 5 - 25} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon } \hfill \\ \end{gathered} $$ . The extraction equilibrium constants (K _ex ) and the two-phase stability constants (β ₃ ^× ) for theLnL ₃(MeOH)₃ complexes have been evaluated.     

Solvent extraction of certain rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The solvent extraction of Yb(III) by 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous—ethanol phase has been investigated as a function of thepH ^X of the polar phase and the concentrations ofPAN or ethanol (EtOH) in the organic phase. It was confirmed that the addition of ethanol to the aqueous phase causes an increase of the Yb(III) distribution coefficient. The equation for the extraction reaction has been suggested as: $$Yb(H_2 O)_{m(^p )}^{3 + } + 3H L_{(o)} + t Et OH_{(o)} \rightleftharpoons Yb L_3 \left( {EtOH} \right)_{t(o)} + 3H_{(^p )}^ + + mH_2 O$$ wheret changes from 0 to 3. The extraction equilibrium constant (K _ex ) and two-phase stability constants (β ₃ ^× ) for the YbL ₃ (EtOH)₃ complex have been evaluated. The formation of solvates YbL ₃ (EtOH) _t is probably the main reason of the synergistic effect which was observed.     

Kinetics and mechanism of oxidation of cis-diaquabis(glycinato)chromium(III) by periodate ion in aqueous solutions

The kinetics of oxidation of cis-[Cr^III(gly)₂(H₂O)₂]⁺ (gly = glycinate) by $ {\text{IO}}_{ 4}^{ - } $ has been studied in aqueous solutions. The reaction is first order in the chromium(III) complex concentration. The pseudo-first-order rate constant, k _obs, showed a small change with increasing $ \left[ {{\text{IO}}_{ 4}^{ - } } \right] $ . The pseudo-first-order rate constant, k _obs, increased with increasing pH, indicating that the hydroxo form of the chromium(III) complex is the reactive species. The reaction has been found to obey the following rate law: $ {\text{Rate}} = 2k^{\text{et}} K_{ 3} K_{ 4} \left[ {{\text{Cr}}\left( {\text{III}} \right)} \right]_{t} \left[ {{\text{IO}}_{ 4}^{ - } } \right]/\left\{ {\left[ {{\text{H}}^{ + } } \right] + K_{ 3} + K_{ 3} K_{ 4} \left[ {{\text{IO}}_{ 4}^{ - } } \right]} \right\} $ . Values of the intramolecular electron transfer constant, k ^et, the first deprotonation constant of cis-[Cr^III(gly)₂(H₂O)₂]⁺, K ₃ and the equilibrium formation constant between cis-[Cr^III(gly)₂(H₂O)(OH)] and $ {\text{IO}}_{ 4}^{ - } $ , K ₄, have been determined. An inner-sphere mechanism has been proposed for the oxidation process. The thermodynamic activation parameters of the processes involved are reported.     

Isosaccharinate Complexes of Fe(III)

Prior to this study there were no thermodynamic data for isosaccharinate (ISA) complexes of Fe(III) in the environmental range of pH (>~4.5). This study was undertaken to obtain such data in order to predict Fe(III) behavior in the presence of ISA. The solubility of Fe(OH)₃(2-line ferrihydrite), referred to as Fe(OH)₃(s), was studied at 22?±?2?°C in: (1) very acidic (0.01?mol·dm^?3 H⁺) to highly alkaline conditions (3?mol·dm^?3 NaOH) as a function of time (11?C421?days), and fixed concentrations of 0.01 or 0.001?mol·dm^?3 NaISA; and (2) as a function of NaISA concentrations ranging from approximately 0.0001 to 0.256?mol·dm^?3 and at fixed pH values of approximately 4.5 and 11.6 to determine the ISA complexes of Fe(III). The data were interpreted using the SIT model that included previously reported stability constants for $ {{\text{Fe(ISA}})_{n}}^{3 - n} $ (with n varying from 1 to 4) and Fe(III)?COH complexes, and the solubility product for Fe(OH)₃(s) along with the values for two additional complexes (Fe(OH)₂(ISA)(aq) and $ {\text{Fe(OH)}}_{ 3} ( {{\text{ISA}})_{2}}^{2 - } $ ) determined in this study. These extensive data provided a log₁₀ K ⁰ value of 1.55?±?0.38 for the reaction $ ({\text{Fe}}^{ 3+ } + {\text{ISA}}^{-} + 2 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH}})_{ 2} {\text{ISA(aq}}) + 2 {\text{H}}^{ + } ) $ and a value of ?3.27?±?0.32 for the reaction $ ({\text{Fe}}^{ 3+ } + 2 {\text{ISA}}^{-} + 3 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH)}}_{ 3} ( {\text{ISA}})_{2}^{2 - } + 3 {\text{H}}^{ + } ) $ and show that ISA forms strong complexes with Fe(III) which significantly increase the Fe(OH)₃(s) solubility at pH?<~12. Thermodynamic calculations show that competition of Fe(III) with tetravalent ions for ISA does not significantly affect the solubilities of tetravalent hydrous oxides (e.g., Th and Np(IV)) in ISA solutions.     

Prediction and correlations between the stability constants of mono- and polynuclear chromium(III) and iron(III) complexes

Correlations between the experimentally determined stability constants of mono- and polynuclear chromium(III) and iron(III) complexes are discussed. An equation to evaluate the stability constants of mono- and polynuclear chromium(III) complexes is obtained: \(\log \beta [Cr_p^{3 + } (L_i )_{q_i } ] = 0.84\log \beta [Fe_p^{3 + } (L_i )_{q_i } ]\) .     

Kinetics and mechanism of Am(III) extraction with TODGA

In the present paper, N,N,N’,N’-tetraoctyl diglycolamide (TODGA) as the extractant and n-dodecane as the diluent, the extraction kinetics behavior of Am(III) in TODGA/n-dodecane–HNO₃ system were studied, including stirring speed, the interfacial area, extractant concentration in n-dodecane, extracted ions concentration, acidity of aqueous phase and temperature. The results show that: the extraction process is controlled by diffusion mode under 130 rpm of stirring speed and by chemical reaction mode above 150 rpm. The extraction rate equation and the apparent extraction rate constant of Am(III) by TODGA/n-dodecane in 170 rpm and at 25 °C are followed as: $$ \begin{aligned} r_{0} = \left. {\frac{{{\text{d}}[{\text{M}}]_{{{\text{org}} .}} }}{{{\text{d}}{{t}}}}} \right|_{t = 0} & = k\,\frac{S}{V}\left[ {\text{Am}} \right]_{{{\text{aq}} . ,0}}^{0.94} \left[ {{\text{HNO}}_{3} } \right]_{{{\text{aq}} . ,0}}^{1.05} \left[ {\text{TODGA}} \right]_{{{\text{org}} . ,0}}^{1.19} \\ & \quad k = \left( {24.17 \pm 3.43} \right) \times 10^{ - 3} \,{\text{mol}}^{ - 2.18} \,L^{2.18} \,{ \hbox{min} }^{ - 1} \,{\text{cm}},\;E_{\text{a}} \left( {{\text{Am}}\left( {\text{III}} \right)} \right) = 25.94 \pm 0.98\;{\text{kJ/mol}} .\\ \end{aligned} $$      

The Oxidation of Iron(II) with Oxygen in NaCl Brines

The oxidation of nanomolar levels of iron(II) with oxygen has been studied in NaCl solutions as a function of temperature (0 to 50?°C), ionic strength (0.7 to 5.6 mol?kg^?1), pH (6 to 8) and concentration of added NaHCO₃ (0 to 10 mmol?kg^?1). The results have been fitted to the overall rate equation: $$\mathrm{d}\mbox{[Fe(II)]}/\mathrm{d}t=-k_{\mathrm{app}}\mbox{[Fe(II)]}[\mbox{O}_{2}]$$ The values of k _app have been examined in terms of the Fe(II) complexes with OH^? and CO ₃ ^2? . The overall rate constants are given by: $$k_{\mathrm{app}}=\alpha_{\mathrm{Fe}2+}k_{\mathrm{Fe}}+\alpha_{\mathrm{Fe(OH)}+}k_{\mathrm{Fe(OH)}+}+\alpha_{\mathrm{Fe(OH)}2}k_{\mathrm{Fe(OH)}2}+\alpha_{\mathrm{Fe(CO3)}2}k_{\mathrm{Fe(CO3)}2}$$ where α _i is the molar fraction and k _i is the rate constant of species i. The individual rate constants for the species of Fe(II) interacting with OH^? and CO ₃ ^2? have been fitted by equations of the form: $$\begin{array}{l}\ln k_{\mathrm{Fe}2+}=21.0+0.4I^{0.5}-5562/T\\[6pt]\ln k_{\mathrm{FeOH}}=17.1+1.5I^{0.5}-2608/T\\[6pt]\ln k_{\mathrm{Fe(OH)}2}=-6.3-0.6I^{0.5}+6211/T\\[6pt]\ln k_{\mathrm{Fe(CO3)}2}=31.4+5.6I^{0.5}-6698/T\end{array}$$ These individual rate constants can be used to estimate the rates of oxidation of Fe(II) over a large range of temperatures (0 to 50?°C) in NaCl brines (I=0 to 6 mol?kg^?1) with different levels of OH^? and CO ₃ ^2? .     

0-aminophenol and 8-hydroxyquinoline as ligands of Cu(II) in 1M-Na(ClO4) at 25°C

The complex formation between Cu(II) and 8-hydroxyquinolinat (Ox) was studied with the liquid-liquid distribution method, between 1M-Na(ClO₄) and CHCl₃ at 25°C. The experimental data were explained by the equilibria: $$\begin{gathered} \operatorname{Cu} ^{2 + } + Ox \rightleftharpoons \operatorname{Cu} Ox \log \beta _1 = 12.38 \pm 0.13 \hfill \\ \operatorname{Cu} ^{2 + } + 2 Ox \rightleftharpoons \operatorname{Cu} Ox_2 \log \beta _2 = 23.80 \pm 0.10 \hfill \\ \operatorname{Cu} Ox_{2aq} \rightleftharpoons \operatorname{Cu} Ox_{2\operatorname{org} } \log \lambda = 2.06 \pm 0.08 \hfill \\ \end{gathered} $$ The equilibria between Cu(II) and o-aminophenolate (AF) were studied potentiometrically with a glass electrode at 25°C and in 1M-Na(ClO₄). The experimental data were explained by the equilibria: $$\begin{gathered} \operatorname{Cu} ^{2 + } + AF \rightleftharpoons \operatorname{Cu} AF \log \beta _1 = 8.08 \pm 0.08 \hfill \\ \operatorname{Cu} ^{2 + } + 2AF \rightleftharpoons \operatorname{Cu} AF_2 \log \beta _2 = 14.60 \pm 0.06 \hfill \\ \end{gathered} $$ The protonation constants ofAF and the distribution constants between CHCl₃?H₂O and (C₂H₅)₂O?H₂O were also determined.     

Kinetics and mechanism of the oxidation of formic acid by thallium(III). Reinvestigation of hydrogen ion dependence

The rate of the oxidation of formic acid by thallium(III) in (Li, H)ClO₄ solutions is not affected by variation in hydrogen ion concentration and the experimental rate law, $$\frac{{ - d\left[ {T\left( {III} \right)} \right]}}{{d t}} = \frac{{k_1 K\left[ {T\left( {III} \right)} \right]\left[ {HCOOCH} \right]}}{{1 + K\left[ {HCOOH} \right]}}$$ is consistent with the mechanism which requires the formation of intermediate complex [HCOOHTl]³⁺ in a rapid preequilibrium followed by its slow decomposition to yield the final products. At 75°,k ₁ andK have the values of 16±1×10^?5 sec^?1 and 7.3±0.5M ^?1 resp.     

Die Ionisation von Triphenylchlormethan durch Metallchloride in Acetonitril

In acetonitrile (AN) solutions the gross constants are determined for the reactions $$Ph_3 CCl + MCl_n ANPh_3 C^ + MCl_{n + 1}^ - + AN$$ (MCl _n =SbCl₅, GaCl₃, InCl₃, and FeCl₃). The relaxation spectra are interpreted for the reactions of metal(III) chlorides according to the equilibria $$\begin{gathered} 2 MCl_3 AN + 6AN \rightleftharpoons [MCl_2 (AN)_4 ]^ + [MCl_4 ]^ - + 4 AN \rightleftharpoons \hfill \\ 2 [MCl_2 (AN)_4 ]^ + Cl - \hfill \\ \end{gathered} $$      

Molecular magnets based on chain polymer complexes of copper(II) bis(hexafluoroacetylacetonate) with isoxazolyl-substituted nitronyl nitroxides

First isoxazolyl-substituted nitronyl nitroxides (L and $L^{Me_2 }$ ) were synthesized and characterized. Their reactions with Cu(hfac)₂ and Mn(hfac)₂ (hfac is hexafluoroacetylacetonate) afford the heterospin complexes [Cu(hfac)₂L] _n , [Cu₂(hfac)₄L] _n , $\left[ {Cu_2 (hfac)_4 L^{Me_2 } } \right]_n$ , $\left[ {Cu(hfac)_2 L^{Me_2 } } \right]_n$ , $\left[ {Cu(hfac)_2 L^{Me_2 } _2 } \right]$ , $\left[ {Cu(hfac)_2 L^{Me_2 } (MeCN)} \right]$ , [Mn(hfac)₂]₃L₄, and $\left[ {Me(hfac)_2 L^{Me_2 } } \right]_2$ . In the ligand L, the N atom of the isoxazole ring (NIz) has weak electron-donating properties. For example, the paramagnetic ligand in the chain polymer complex [Cu(hfac)₂L] _n acts as a bidentate bridging ligand coordinated through both O atoms of the nitronyl nitroxide group (O_N-O); the N_Iz and O_Iz atoms are not involved in the coordination. The introduction of Me groups into the isoxazole substituent results in an increase in the electron density on the N_Iz atom and enables the synthesis of the chain polymer complex $\left[ {Cu(hfac)_2 L^{Me_2 } } \right]_n$ , in which the bidentate bridging ligand $L^{Me_2 }$ is coordinated through the O_N-O and N_Iz atoms. In the mononuclear complexes $\left[ {Cu(hfac)_2 L^{Me_2 } _2 } \right]$ and $\left[ {Cu(hfac)_2 L^{Me_2 } (MeCN)} \right]$ , the paramagnetic ligand is coordinated only through the N_Iz atom. The solid heterospin Mn complexes [Mn(hfac)₂]₃L₄ and $\left[ {Mn(hfac)_2 L^{Me_2 } } \right]_2$ have a molecular structure. In these complexes, strong antiferromagnetic intracluster exchange interactions arise. The residual magnetic moments of the exchange clusters in the complex [Mn(hfac)₂]₃L₄ are ferromagnetically coupled, resulting in the increase in the effective magnetic moment (??_eff) of the complex with decreasing temperature in the range of 300??30 K. The thermomagnetic study of the complexes [Cu(hfac)₂L] _n , [Cu₂(hfac)₄L] _n , and $\left[ {Cu_2 (hfac)_4 L^{Me_2 } } \right]_n$ in the range of 2?C300 K revealed the ferromagnetic ordering at temperatures below 5 K. The ESR study of the solid complex $\left[ {Cu(hfac)_2 L^{Me_2 } } \right]_n$ showed that the decrease in its ??_eff in the temperature range of 30?C300 K is associated with the direct exchange interaction between the unpaired electrons of the nitronyl nitroxides of adjacent chains, whereas at temperatures below 30 K, only Cu²⁺ ions contribute to the magnetic susceptibility of the complex.     

Thermochemical properties of the coordination complex of 8-hydroxyquinolinato-bis-(salicylato) praseodymium (III)

The product, [Pr(C₇H₅O₃)₂(C₉H₆NO)], which was formed by praseodymium nitrate hexahydrate, salicylic acid (C₇H₆O₃), and 8-hydroxyquinoline (C₉H₇NO), was synthesized and characterized by elemental analysis, UV spectra, IR spectra, molar conductance, and thermogravimetric analysis. In an optimalizing calorimetric solvent, the dissolution enthalpies of [Pr(NO₃)₃·6H₂O(s)], [2 C₇H₆O₃(s) + C₉H₇NO(s)], [Pr(C₇H₅O₃)₂(C₉H₆NO)(s)], and [solution D (aq)] were measured to be, by means of a solution-reaction isoperibol microcalorimeter, $ \begin{gathered}\Updelta_{\text{s}} H_{\text{m}}^{\theta}\left[ {{ \Pr }\left( {{\text{NO}}_{ 3} } \right)_{ 3} \cdot 6{\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right), 2 9 8. 1 5{\text{ K}}} \right] \, = - ( 20. 6 6 { } \pm \, 0. 29)\,{\text{kJ}}\,{\text{mol}}^{ - 1} , \\\Updelta_{\text{s}} H_{\text{m}}^{\theta } \left[ { 2 {\text{C}}_{7} {\text{H}}_{ 6} {\text{O}}_{ 3} \left( {\text{s}} \right) +{\text{ C}}_{ 9} {\text{H}}_{ 7} {\text{NO}}\left( {\text{s}}\right),{ 298}. 1 5 {\text{ K}}} \right] \, = \, ( 4 2. 2 7 { }\pm \, 0. 3 1)\,{\text{kJ}}\,{\text{mol}}^{ - 1} , \\\Updelta_{\text{s}} H_{\text{m}}^{\theta } \left[ {{\text{solutionD }}\left( {\text{aq}} \right), 2 9 8. 1 5 {\text{ K}}} \right] \,= - \left( { 8 9. 1 5 { } \pm \, 0. 4 3}\right)\,{\text{kJ}}\,{\text{mol}}^{ - 1} , \\\end{gathered} $ Δ s H m θ [ Pr ( NO 3 ) 3 · 6 H 2 O ( s ) , 2 9 8.1 5 K ] = ? ( 20.6 6 ± 0.2 9 ) kJ mol ? 1 , Δ s H m θ [ 2 C 7 H 6 O 3 ( s ) + C 9 H 7 NO ( s ) , 298.1 5 K ] = ( 4 2.2 7 ± 0.3 1 ) kJ mol ? 1 , Δ s H m θ [ solution D ( aq ) , 2 9 8.1 5 K ] = ? ( 8 9.1 5 ± 0.4 3 ) kJ mol ? 1 , and $ \Updelta_{\text{s}} H_{\text{m}}^{\theta } \left\{ {\left[ {{\Pr }\left( {{\text{C}}_{ 7} {\text{H}}_{ 5} {\text{O}}_{ 3} }\right)_{ 2} \left( {{\text{C}}_{ 9} {\text{H}}_{ 6} {\text{NO}}}\right)} \right]\left( {\text{s}} \right),{ 298}. 1 5 {\text{ K}}}\right\} \, = - \left( { 4 1.0 4 { } \pm \, 0. 3 3}\right)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ Δ s H m θ { [ Pr ( C 7 H 5 O 3 ) 2 ( C 9 H 6 NO ) ] ( s ) , 298.1 5 K } = ? ( 4 1.0 4 ± 0.3 3 ) kJ mol ? 1 , respectively. Through an improved thermochemical cycle, the enthalpy change of the designed coordination reaction was calculated to be $\Updelta_{\text{r}} H_{\text{m}}^{\theta} = \, ( 2 1 3. 1 8\pm0. 6 9)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ Δ r H m θ = ( 2 1 3.1 8 ± 0.6 9 ) kJ mol ? 1 , the standard molar enthalpy of the formation was determined as $ \Updelta_{\text{f}} H_{\text{m}}^{\theta} \left\{ {\left[ {{\Pr }\left( {{\text{C}}_{ 7} {\text{H}}_{ 5} {\text{O}}_{ 3} }\right)_{ 2} \left( {{\text{C}}_{ 9} {\text{H}}_{ 6} {\text{NO}}}\right)} \right]\left( {\text{s}} \right), 2 9 8. 1 5 {\text{K}}}\right\} \, = \, - \, ( 1 8 7 5. 4\pm 3.1)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ Δ f H m θ { [ Pr ( C 7 H 5 O 3 ) 2 ( C 9 H 6 NO ) ] ( s ) , 2 9 8.1 5 K } = ? ( 1 8 7 5.4 ± 3.1 ) kJ mol ? 1 .     

Inner-sphere oxidation of a ternary dipicolinatochromium(III) complex involving a malonic acid co-ligand

The oxidation of a ternary complex of chromium(III), [Cr^III(DPA)(Mal)(H₂O)₂]^?, involving dipicolinic acid (DPA) as primary ligand and malonic acid (Mal) as co-ligand, was investigated in aqueous acidic medium. The periodate oxidation kinetics of [Cr^III(DPA)(Mal)(H₂O)₂]^? to give Cr(VI) under pseudo-first-order conditions were studied at various pH, ionic strength and temperature values. The kinetic equation was found to be as follows: \( {\text{Rate}} = {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} \mathord{\left/ {\vphantom {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}}} \right. \kern-0pt} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}} \) where k ₆ (3.65 × 10^?3 s^?1) represents the electron transfer reaction rate constant and K ₄ (4.60 × 10^?4 mol dm^?3) represents the dissociation constant for the reaction \( \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)_{2} } \right]^{ - } \rightleftharpoons \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)\left( {\text{OH}} \right)} \right]^{2 - } + {\text{H}}^{ + } \) and K ₅ (1.87 mol^?1 dm³) and K ₆ (22.83 mol^?1 dm³) represent the pre-equilibrium formation constants at 30 °C and I = 0.2 mol dm^?3. Hexadecyltrimethylammonium bromide (CTAB) was found to enhance the reaction rate, whereas sodium dodecyl sulfate (SDS) had no effect. The thermodynamic activation parameters were estimated, and the oxidation is proposed to proceed via an inner-sphere mechanism involving the coordination of IO₄ ^? to Cr(III).     

Kinetic Study of the Interaction of Three Glycine-Containing Dipeptides with Hydroxopentaaquarhodium(III) Ion in Aqueous Medium

The kinetics of the interaction of three glycine-containing dipeptides, namely, glycyl-L-valine (L¹-L??H), glycyl-glycine (L²-L??H) and glycyl-L-glutamine (L³-L??H), with [Rh(H₂O)₅OH]²⁺ has been studied spectrophotometrically in aqueous medium as a function of the Rh(H₂O)₅OH²⁺ and dipeptide concentrations, pH and temperature, at constant ionic strength. At pH = 4.3, the substrate complex exists predominantly as the hydroxopentaaqua species and dipeptides as zwitterions. The reaction has been found to proceed via two parallel paths: both processes are ligand dependent. The rate constants for the processes are of the order: k ₁??10^?3 s^?1 and k ₂??10^?5 s^?1. The activation parameters for both steps were evaluated from Eyring plots. Based on the kinetic and activation parameters an associative interchange mechanism is proposed for both of the interaction processes. The low $\Delta H_{1}^{\neq}$ and $\Delta H_{2}^{\neq}$ values and large negative values of $\Delta S_{1}^{\neq}$ and $\Delta S_{2}^{\neq}$ support the associative mode of activation for both processes. The product of the reaction has been characterized using IR and ESI-mass spectroscopic analysis.     

Relation générale entre l'indice de liaison et la distance interatomique dans les molécules conjuguées,planes et linéaires

Two general relation between bond orderl and bond distance d (Å) are proposed:

1. between atomssp ₂-hybridised of second and third row: $$d_{PQ} = \left[ {0,731 + 0,3181\left( {n_P + n_Q } \right) - 0,1477\left( {\zeta _P + \zeta _Q } \right)} \right] - 0,020 + 0,0523\left( {\zeta _P + \zeta _Q } \right)l_{PQ} $$ ,ζ=Z/n,Z=Slater's effective nuclear charge of theπ-orbital).
2. between atomssp-hybridised of the second row: $$d_{PQ} = \left[ {1,904 - 0,123\left( {\zeta _P + \zeta _Q } \right)} \right] - \left[ {0,075 + 0,023\left( {\zeta _P + \zeta _Q } \right)} \right]l_{PQ} $$ (l=total bond orderπ+π′).

     

Lumineszenzspektren von ein- und zweikernigen Chrom(III)-Glycin-Komplexverbindungen

The luminescence spectra of the polycrystalline compounds [Cr(CH₂NH₂COO)₃ · H₂O] and [Cr₂(OH)₂(CH₂NH₂COO)₄] are investigated in the temperature range of 120K – 4.2K. From the known crystal structure (P2_1/c =D _2h ^/5 ) of the mononuclear compound assignment of the zero-phonon bands based on crystal field theory becomes possible. Both of the highly intense phosphorescence transitions are observed at \(P_1 = 14493 cm^{ - 1} ({}^2A'' \xrightarrow{{0.0}} {}^4A) and P_2 = 14428 cm^{ - 1} ({}^2A' \xrightarrow{{0.0}} {}^4A)\) . Assignment of the accompanying vibronic bands is made from the measured infrared data. Crystal field parameters Dq, B and C are determined from the luminescence and reflectance spectra. In the case of the binuclear compound the Cr³⁺-Cr³⁺ interaction via hydroxyl brides may be described by an axchange operator \(H_{ex} = - 2 \sum\limits_{ij} {J_{ij} S_i^a \cdot S_j^a } \) and from this the energy level diagram is calculated. Both observed strong phosphorescence bands at 14369 cm^?1 and 14184 cm^?1 are assigned to \(\left| {{}^2E \cdot {}^4A_2 \rangle _{s = 2} \xrightarrow{{0.0}}} \right| {}^4A_2 \cdot {}^4A_2 \rangle _{s = 2} and \left| {{}^2E \cdot {}^4A_2 \rangle _{s = 1} \xrightarrow{{0.0}}} \right| {}^4A_2 \cdot {}^4A_2 \rangle _{s = 1} \) transitions.     

Solvation state of iron(III) in aqueous solutions of dimethyl sulfoxide. Complex formation ability of iron(III) with respect to derivatives of <Emphasis Type="Italic">sym</Emphasis>-triazine and bis(hydrazinocarbonylmethyl) sulfoxide

Parameters of the solvation equilibria \({\left[ {Fe{{\left( {{H_2}O} \right)}_6}} \right]^{3 + }} + nDMSO \rightleftarrows {\left[ {Fe{{\left( {{H_2}O} \right)}_{6 - n}}{{\left( {DMSO} \right)}_n}} \right]^{3 + }} + n{H_2}O\) have been determined in aqueous-dimethyl sulfoxide solutions (0–90 vol% DMSO) by means of spectrophotometry and mathematical modeling of equilibria. Iron(III) is not involved in the complex formation with derivatives of sym-triazine: 2,4-diamino-6-(carbamoylmethylsulfinylmethyl)-1,3,5-triazine and 2,4-diamino-6-(acetohydrazidomethylsulfinylmethyl)-1,3,5-triazine in aqueous DMSO medium (40 vol % DMSO). Bis(hydrazinocarbonylmethyl) sulfoxide forms two complexes with iron(III), with 1: 1 and 1: 2 compositions; in contrast to the Cu(II) and Ni(II) complexes, in the iron complexes the ligand exists in the amide form. The most probable structures of the complexes have been revealed by molecular mechanics simulation and (in selected cases) using the DFT/B3LYP/6-31++G(d,p) density functional theory method.     

Bemerkung zur Rayleigh-Schrödinger-Störungstheorie

The time-independent Hamiltonians ? ₀ and ?=? ₀ + V have a discrete spectrum, eigenvalues, and eigenvectors E _s ^(o) , ¦s〉^(o) resp. E _s, ¦s〉. If the RS perturbation theory can be applied here then an operator \(\mathfrak{p}\) with the property $$\left| s \right\rangle ^{(n + 1)} = \frac{1}{{n + 1}}\mathfrak{p}\left| s \right\rangle ^{(n)} , E_s^{(n + 1)} = \frac{1}{{n + 1}}\mathfrak{p}E_s^{(n)} $$ exists where ¦s〉⁽ⁿ⁾ and E _s ⁽ⁿ⁾ denote the n-th order corrections of perturbation theory if E _s ^(o) is nondegenerate. In the case of degeneracy the operation \(\mathfrak{p}\) remains defined and can always be used todetermine perturbation corrections of quantum mechanical expressions which are invariant in zerothorder under transformations of the basis in degenerate subspaces of ? ₀. The equations $$\left| s \right\rangle = \sum\limits_n^{0,\infty } {\left| s \right\rangle ^{(n)} = e^\mathfrak{p} \left| s \right\rangle ^{(0)} } , E_s = \sum\limits_n^{0,\infty } {E_s^{(n)} } = e^\mathfrak{p} E_s^{(0)} $$ correspond to a basis transformation where nondegenerate eigenvectors ¦s∝> ^(o) and eigenvalues E _s ^(o) of ? ₀ transform into eigenvectors ¦s∝> and eigenvalues E _s of ?. Examples show the usefulness of this formulation.