Heat capacity and thermodynamic functions of CsCrCl3 and RbCrCl3. Structural phase transitions

We present the heat capacities measured by adiabatic calorimetry from 6 to 350 K, and by differential scanning calorimetry from 300 to 500 K, of CsCrCl₃ and RbCrCl₃. A first-order transition at T_c = (171.1±0.1) K was detected for CsCrCl₃. The RbCrCl₃ showed at T_c = (193.3±0.1) K a transition with thermal hysteresis at temperatures just below the maximum. At T₁ = (440±10) K a continuous transition was also detected. Furthermore, at T_N ≈ 16 K, and for both compounds, a small bump due to magnetic long-range ordering was observed. The thermodynamic functions at 298.15 K are

     

2.

Cesium chromate,Cs2CrO4: heat capacity and thermodynamic properties from 5 to 350 K     

William G. Lyon  Darrell W. Osborne  Howard E. Flotow 《The Journal of chemical thermodynamics》1975,7(12):1189-1194

The heat capacity of a sample of Cs₂CrO₄ was determined in the temperature range 5 to 350 K by aneroid adiabatic calorimetry. The heat capacity at constant pressure C_p^o(298.15 K), the entropy S^o(298.15 K), the enthalpy {H^o(298.15 K) - H^o(0)} and the function $\text{? {G}{}^{\mathrm{o}}\text{(298.15}\text{K}\text{) - H}{}^{\mathrm{o}}\text{(0)}}\text{298.15}\text{K}$ were found to be (146.06 ± 0.15) J K^?1 mol^?1, (228.59 ± 0.23) J K^?1 mol^?1, (30161 ± 30) J mol^?1, and (127.43 ± 0.13) J K^?1 mol^?1, respectively. The heat capacity C_p^o(298.15 K) and entropy S^o(298.15 K) and entropy S^o(298.15 K) of Rb₂CrO₄ are estimated to be (146.0 ± 1.0) J K^?1 mol^?1 and (217.6 ± 3.0) J K^?1 mol^?1, respectively.     

3.

Mutual solubility of n-butanol + water under high pressures     

Yasuhiro Aoki  Takashi Moriyoshi 《The Journal of chemical thermodynamics》1978,10(12):1173-1179

The mutual solubilities of {xCH₃CH₂CH₂CH₂OH+(1-x)H₂O} have been determined over the temperature range 302.95 to 397.75 K at pressures up to 2450 atm. An increase in temperature and pressure results in a contraction of the immiscibility region. The results obtained for the critical solution properties are: T_o(U.C.S.T.) = 397.85 K and x_o = 0.110 at 1 atm; $\text{(}\text{dT}{}_{\mathrm{o}}\text{d}\text{p}\text{) = ?(12.0±0.5)×10}{}^{\mathrm{?3}}\text{K atm}{}^{\mathrm{?1}}$ at p < 400 atm and $\text{(}\text{dT}{}_{\mathrm{o}}\text{d}\text{p}\text{) = ?(7.0±0.7)×10}{}^{\mathrm{?3}}\text{K atm}{}^{\mathrm{?1}}$ at 800 atm < p < 2500 atm; $\text{(}\text{dx}{}_{\mathrm{o}}\text{d}\text{T}\text{) = ?(4.0±0.5)×10}{}^{\mathrm{?4}}\text{K}{}^{\mathrm{?1}}$.     

4.

Synthesis of homoleptic tris(organo-chelate)iridium(III) complexes by spontaneous ortho-metallation of electronrich olefin-derived N,N′-diarylcarbene ligands and the X-ray structures of fac-[Ir{CN(C6H4Me-p) (CH2)2NC6H3Me-p}3] and mer-Ir{CN(C6H4Me-p)(CH2)2NC6H3Me-p}2 {CN(C6H4Me-p)(CH2)2NC6H4Me-p}Cl (a product of HCl cleavage)     

Peter B. Hitchcock  Michael F. Lappert  Pilar Terreros 《Journal of organometallic chemistry》1982,239(2):C26-C30

Treatment of [{Ir(COD)(μ-Cl)}₂] with excess of the electron-rich olefin [$\text{CN(Ar)(CH}{}_2\text{)}{}_2\text{N}$Ar]₂ (abbreviated as (L^Ar)₂, Ar = C₆H₄Me-p or C₆H₄OMe-p) affords the ortho-metallated tricycle [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₃], which for Ar = C₆H₄Me-p (Ia) with HCL yields [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₂(L^Ar)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir?C(o-aryl) contact (2;52(1) Å) involving the “free” L^Ar which compares with an IrC(o-aryl) distance of 2.09(3) Å in Ia or 2.07(3) Å in the ortho-metallated L^Ar ligand of complex IV.     

5.

Determination of the vapour pressures of o-, m-, and p-dinitrobenzene by the torsion-effusion method     

D. Ferro  V. Piacente  R. Gigli  G. D&#x;Ascenzo 《The Journal of chemical thermodynamics》1976,8(12):1137-1143

The vaporization of o-, m-, and p-dinitrobenzenes was investigated by means of the torsion-effusion method and the selected equations for vapour pressure p as a function of temperature T are:

$\text{o-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(7.03±0.34)?(4270±120)}\text{K}\text{T}\text{,m-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(7.66±0.28)?(4400±100)}\text{K}\text{T}\text{,p-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(8.34±0.34)?(4860±120)}\text{K}\text{T}$

The sublimation enthalpies ΔH^o(o-, 298.15 K) = (21.0 ± 0.5) kcal_th mol^?1, ΔH^o(m-, 298.15 K) = (20.8 ± 0.2) kcal_th mol^?1, and ΔH^o(p-, 298.15 K) = (23.0 ± 0.6) kcal_th mol^?1, are also derived by means of the second- and third-law treatments of the results.     

6.

Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen XX. Darstellung,eigenschaften und kristallstruktur von λ4-thia-λ5-phospha-h2-metallabicyclo[2.2.1]heptadienen und ihre verwendung zur synthese von metallorganischen und organischen verbindungen     

Ekkehard Lindner  Axel Rau  Sigurd Hoehne 《Journal of organometallic chemistry》1981,218(1):41-60

The novel λ⁴-thia-λ⁵-phospha-h²-manganabicyclo[2.2.1]heptadienes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{PR}{}^1{}_2\text{S}$] (R¹ = CH₃, C₆H₅; R² = CO₂CH₃, CO₂C₂H₅, CO₂C₆H₁₁) are formed by action of the activated alkynes R²C  CR² on the heterocycles [(OC)₄MnPR¹₂S]₂ via the isolable, five-membered heterometallacyclopentadienes (OC)₄$\text{MnSPR}{}^1{}_2\text{C(R}{}^2\text{)C}$(R²). The compound with R¹ = CH₃ and R² = CO₂CH₃ crystallizes in the triclinic space group P$\text{1}$ with Z = 2 and separates quantitatively the thiophene derivative $\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{S}$ under CO pressure or by reaction with (NH₄)₂Ce(NO₃)₆. The use of various acetylenes and of acetylenes with different alkyl groups yields the unsymmetric substituted manganabicycloheptadienes (OC)₃Mn[$\text{CR}{}^4\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P(CH}{}_3\text{)}{}_2\text{S}$] (R² = CO₂CH₃, R³ = R⁴ = CO₂C₂H₅; R² = R⁴ = CO₂CH₃, R³ = H). With propionic acid methylester the alkyne insertion proceeds regiospecifically. With Raney nickel selective S elimination under ring contraction and formation of the λ⁴-phospha-h²-manganabicyclo[2.1.1]hexenes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$R¹₂] (R¹ = CH₃: R² = R³ = CO₂CH₃, CO₂C₂H₅; R² = CO₂CH₃, R³ = H; R¹ = C₆H₅: R² = R³ = CO₂C₂H₅) occurs. (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$(CH₃)₂] (R² = R³ = CO₂CH₃) crystallizes in the monoclinic space group P2₁/m with Z = 2. The IR and NMR spectra of the heterocycles are discussed in detail.     

7.

Thermophysics of alkali and related azides II. Heat capacities of potassium,rubidium, cesium,and thallium azides from 5 to 350 K     

Robert W Carling  Edgar F Westrum 《The Journal of chemical thermodynamics》1978,10(12):1181-1200

The heat capacities of potassium, rubidium, cesium, and thallium azides were determined from 5 to 350 K by adiabatic calorimetry. Although the alkali-metal azides studied in this work exhibited no thermal anomalies over the temperature range studied, thallium azide has a bifurcated anomaly with two maxima at (233.0±0.1) K and (242.04±0.02) K. The associated excess entropy was 0.90 cal_th K^?1 mol^?1. The thermal properties of the azides and the corresponding structurally similar hydrogen difluorides are nearly identical. Both have linear symmetrical anions. However, thallium azide shows a solid-solid phase transition not exhibited by thallium hydrogen difluoride. At 298.15 K the values of C_p^o, S^o, and $\text{?{G}{}^{\mathrm{o}}\text{(T)?H}{}^{\mathrm{o}}\text{(0)}}\text{T}$, respectively, are 18.38, 24.86, and 12.676 cal_th K^?1 mol^?1 for potassium azide; 19.09, 28.78, and 15.58 cal_th K^?1 mol^?1 for rubidium azide; 19.89, 32.11, and 18.17 cal_th K^?1 mol^?1 for cesium azide; and 19.26, 32.09, and 18.69 cal_th K^?1 mol^?1 for thallium azide. Heat capacities at constant volume for KN₃ were deduced from infrared and Raman data.     

8.

Extraction of indium(III) from chloride medium with 1-phenyl-3-methyl-4-acylpyrazol-5-ones. Synergic effect with high molecular weight ammonium salts.     

J.P. Brunette  M. Taheri  G. Goetz-Grandmont  M.J.F. Leroy 《Polyhedron》1982,1(5):457-460

The extraction of In(III) from 1M (Na,H)(Cl,ClO₄) media with 4-acylpyrazol-5-ones (HL) in toluene at 25°C is described by equilibria In ³⁺ + 3 $\text{HL}$ ? $\text{InL}{}_3$ + 3 H⁺ (log K = 1.48, 1.03, 0.87 with acyl = benzoyl, lauroyl, 2-thenoyl), InCl ²⁺ + 2 $\text{HL}$ ? $\text{InClL}{}_2$ + 2 H⁺ (log K = 0.26, ?0.45, ?0.35 respectively) and In³⁺ + m Cl^? ? InCl_m^(3-m)+ (log β_m available from literature). The extraction from 1M (Na,H)(Cl,NO₃) medium is enhanced by addition of aliquat (TOMA⁺,Cl^?) and the following synergic equilibrium takes place : $\text{InCl}{}_2$ + $\text{(TOMA}{}^{\mathrm{+}}$,Cl^?) ? $\text{(TOMA}{}^{\mathrm{+}}$, InCl₂L₂^? (log K = 5.49, 5.25, 5.21 respectively). Cl^? of (TOMA⁺,Cl^?) is exchanged by NO₃^? with the equilibrium constant log K = 1.50. If (TOMA⁺,Cl^?) is replaced by tri-n-octylammonium chloride, the synergic effect is largely reduced (log K = 4.17 with acyl = benzoyl). The extraction from chloride solutions containing ClO₄^? remains unchanged by addition of ammonium salts.     

9.

Etude comparative des structures type K₄NiF₄ et pérovskite par la méthode des invariants     

Paul Poix 《Journal of solid state chemistry》1981,40(2):175-179

The study of K₂NiF₄ and perovskite structure type by the “method of invariants” leads to the relationship: $\text{(A-X)}{}_9\text{2}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? (A-X)}{}_{12}\text{=}\text{constant}$, where (A-X)₉ and (A-X)₁₂ are the invariant values associated with cation A in coordination number 9 and 12. In the case where A = K⁺ and X = F^?, we propose the relationship:

$\text{(K}{}^{\mathrm{+}}\text{?F)}{}_{\mathrm{R}}\text{= 2.832 R}{}^{\mathrm{<mtext>1</mtext><mtext>11.4</mtext>}}$

where R is the coordination number.     

10.

Thermodynamic properties of two metal-rich tantalum sulfides: Ta₂S and Ta₆S     

B.U. Harbrecht  S.R. Schmidt  H.F. Franzen 《Journal of solid state chemistry》1984,53(1):113-119

The incongruent vaporization reactions of Ta₂S and Ta₆S have been investigated by mass-loss effusion in the temperature range 1576 to 1902 K. By extrapolation of P_S(obs) to equilibrium the enthalpies of the reactions $\text{3}\text{2}\text{Ta}{}_2\text{S(s)}\text{=}\text{1}\text{2}\text{Ta}{}_6\text{S(s) + S(g)}$ and Ta₆S = 6 Ta(s) + S(g) were found to be $\text{ΔH}{}^0{}_{298}\text{R}\text{= 53.0(0.3) · 10}{}^3\text{K}$ and $\text{ΔH}{}^0{}_{298}\text{R}\text{= 58.1(0.4) · 10}{}^3\text{K}$, respectively. Comparison between the above values, determined by a 2nd law treatment, and 3rd law values was used to derive fef (“free energy function”) values for Ta and S in the compounds. These postulated fef's, which apply only to the elements as present in the compounds measured, are compared to tabulated quantities for the pure solid elements to provide a criterion for 2nd and 3rd law evaluation.     

11.

Determination of temperature dependence of limiting activity coefficients for a group of moderately hydrophobic organic solutes in water     

《Fluid Phase Equilibria》2002,201(1):135-164

     

12.

Standard enthalpy of solution and formation of cesium chromate. Derived thermodynamic properties of the aqueous chromate,bichromate, and dichromate ions,alkali metal and alkaline earth chromates,and lead chromate     

P.A.G. O&#x;Hare  Juliana Boerio 《The Journal of chemical thermodynamics》1975,7(12):1195-1204

Calorimetric measurements of the enthalpy of solution of cesium chromate gave ΔH_soln = (7622 ± 24) cal_th mol^?1 for a dilution of Cs₂CrO₄·21128H₂O. This result, along with the enthalpy of dilution gave the standard enthalpy of solution, ΔH_soln^o = (7512 ± 31) cal_th mol^?1, whence the standard enthalpy of formation, ΔH_f⁰(Cs₂CrO₄, c, 298.15 K), was calculated to be ?(341.78 ± 0.46) kcal_th mol^?1. Recomputed thermodynamic data for the formation of the other alkali metal chromates have been tabulated. From their solubilities and enthalpies of solution, the standard entropies, S⁰(298 K), of BaCrO₄ and PbCrO₄ were estimated to be (38.9 ± 0.9) and (43.7 ± 1.2) cal_th K^?1 mol^?1, respectively. There is evidence that ΔH_f⁰(SrCrO₄, c, 298.15 K) may be in error. Thermochemical, solubility, and equilibrium data, have been combined to update the thermodynamic properties of the aqueous chromate (CrO₄^2?), bichromate (HCrO₄^?), and dichromate (Cr₂O₇^2?) ions. The new values at 298.15 K are as follows:

	$\text{C}{}_{\mathrm{<mtext>p,</mtext><mtext>m</mtext>}}\text{R}$	$\text{S}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{R}$	$\text{{H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(T)?H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(0)}}\text{R}\text{K}$	$\text{?{G}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(T)?H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(0}}\text{RT}$
CsCrCl3	15.38	26.49	3503.2	14.735
RbCrCl3	15.76	25.99	3556.8	14.384

     

13.

Dilute solution properties of poly(N-vinyl-3,6-dibromo carbazole)—III. Phase equilibrium studies     

J. M. Barrales-Rienda  P. A. Galera Gmez 《European Polymer Journal》1984,20(12):1213-1221

The phase relationships of poly(N-vinyl-3,6-dibromo carbazole) (PVK-3, 6-Br₂) were examined for four solvents, viz, o-chlorophenol, p-chloro-m-cresol, o-dichlorobenzene and bromobenzene. Upper critical solution temperatures (UCST) have been determined for solutions of PVK-3,6-Br, fractions in o-chlorophenol and p-chloro-m-cresol over the molecular weight range $\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{× 10}{}^{\mathrm{?4}}\text{= 125.0}\text{to}\text{4.8}$. The Flory temperature, θ, obtained from UCST for the PVK-3,6-Br₂/o-chlorophenol and PVK-3,6-Br₂/p-chloro-m-cresol systems are 66.0 and 112.9°C, respectively. The θ-temperatures were checked against molecular weight and viscosity data to determine the Mark-Houwink equations for these two theta solvents, with satisfactory agreement. The relations are

$\text{[ν] = 27.5}{}_4\text{× 10}{}^{\mathrm{?10}}\text{×}\text{M}{}^{0.50}{}_{\mathrm{<mtext>w</mtext>}}\text{(o-}\text{chlorophenol}\text{, 60.0°}\text{C}$

$\text{[ν] = 30.2}{}_4\text{× 10}{}^{\mathrm{?10}}\text{×}\text{M}{}^{0.50}{}_{\mathrm{<mtext>w</mtext>}}\text{(p-}\text{chloro}\text{-m}\text{cresol}\text{, 112.9°}\text{C}$

The characteristic ratio C_∞ = 〈R²〉₀/nl² was found to be 16.6 in o-chlorophenol at 60.0°C and 17.6 in p-chloro-m-cresol at 112.9°C. The value of the characteristic ratio C_∞ of PVK-3,6-Br₂ is of the same order of that for poly(N-vinyl carbazole). This indicates that the bromine atoms at the 3 and 6 (meta) positions have only an inappreciable effect on the hindering potential for rotation about the CC bond. This agreement of C_∞ for both polymers may also be taken as indicating that the effect of interaction between polar groups at the m-position on the hindering potential for rotation is small. The phase diagrams of PVK-3,6-Br₂ obtained in o-dichlorobenzene and bromobenzene seem to be characteristic of organized phase structures such as those found in systems exhibiting thermoreversible gelation. Light scattering measurement on PVK-3,6-Br₂ dissolved in o-dichlorobenzene, a gelation promoting solvent, and tetrahydrofuran, a very good solvent, strongly indicate that the macromolecular species in o-dichlorobenzene contain some extent supermolecular structures (aggregates, association of chain segments, etc.). These characteristic structures of PVK-3,6-Br₂ in o-dichlorobenzene and bromobenzene at 25°C are also characterized by high values of the Huggins' constant k′; for tetrahydrofuran solutions, the k′ values were in the range normally found for many good solvent-polymer systems.     

14.

Cyclopentadienyl-ruthenium and -osmium chemistry: XXIV. Some complexes containing the olefinic tertiary phosphine 2-CH2CHC6H4PPh2 (sp): X-ray structures of one isomer of OsBr(sp)(η-C5H5), and of Ru(η3-S2CCHMeC6H4PPh2-2)(η-C5H5), containing an η3-dithiocarboxylato group     

Michael I. Bruce  Trevor W. Hambley  Michael R. Snow  A.Geoffrey Swincer 《Journal of organometallic chemistry》1984,273(3):361-376

Reactions between MX(PPh₃)₂(η-C₅H₅) (M = Ru, X = Cl; M = Os, X = Br) and 2-CH₂CHC₆H₄PPh₂ afford $\text{MX(η}{}^2\text{-CH}{}_2\text{CHC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅); the Os complex is obtained in two isomeric forms. The X-ray structure of the major isomer shows the CC double bond (OsC, 2.214, 2.195 Å; CC, 1.57 Å) is almost coplanar with the OsBr vector, with the terminal C cis to Br; the minor isomer is assumed to have the alternative, more sterically congested conformation, with the β-C cis to Br. The chlororuthenium complex reacts with NaOMe/MeOH to give the corresponding hydrido complex, which also exists as two isomers in solution; reaction of this complex with CS₂ gives the expected dithio acid derivative $\text{Ru(S}{}_2\text{CCHMeC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅), together with small amounts of a complex assumed to be $\text{Ru[S}{}_2\text{C(CH}{}_2\text{)}{}_2\text{C}{}_6\text{H}{}_4\text{P}$Ph₂](η-C₅H₅). The X-ray structure of the major product reveals an unusual η³-S₂C mode of coordination of the dithio acid fragment (RuS, 2.418, 2.426(1) Å; RuC 2.175(4) Å). Crystals of OsBr(η²-CH₂CHC₆H₄P)Ph₂)( η-C₅H₅) are monoclinic, space group P2₁/n, with a 12.696(2), b 21.719(6), c 15.929(3) Å, β 79.77(2)°, Z = 8; 2867 data (I > 2.5σ(I)) were refined to R = 0.040, R_w = 0.044. Crystals of $\text{Ru(η}{}^3\text{-S}{}_2\text{CCHMeC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅) are orthorhombic, space group Pbca, with a 8.921(2), b 15.982(9), c 32.216(5) Å, Z = 8; 1685 data (I > 2.5σ(I)) were refined to R = 0.027, R_w = 0.030.     

15.

Nonstoichiometry and defect structure of the perovskite-type oxides La_1−xSr_xFeO_3−°     

Junichiro Mizusaki  Masafumi Yoshihiro  Shigeru Yamauchi  Kazuo Fueki 《Journal of solid state chemistry》1985,58(2):257-266

In order to elucidate the defect structure of the perovskite-type oxide solid solution La_1?xSr_xFeO_3?δ (x = 0.0, 0.1, 0.25, 0.4, and 0.6), the nonstoichiometry, δ, was measured as a function of oxygen partial pressure, P_O2, at temperatures up to 1200°C by means of the thermogravimetric method. Below 200°C and in an atmosphere of P_O2 ≥ 0.13 atm, δ in La_1?xSr_xFeO_3?δ was found to be close to 0. With decreasing log P_O2, δ increased and asymptotically reached $\text{x}\text{2}$. The value corresponding to $\text{δ =}\text{x}\text{2}$ was about ?10 at 1000°C. With further decrease in log P_O2, δ slightly increased. For LaFeO_3?δ, the observed δ values were as small as <0.015. It was found that the relation between δ and log P_O2 is interpreted on the basis of the defect equilibrium among Sr′_La (or V?_La for the case of LaFeO_3?δ), V^··_O, Fe′_Fe, and Fe^·_Fe. Calculations were made for the equilibrium constants K_ox of the reaction

$\text{1}\text{2}\text{O}{}_2\text{(g) + V}{}^{\mathrm{··}}{}_{\mathrm{o}}\text{+ 2Fe}{}^{\mathrm{x}}{}_{\mathrm{Fe}}\text{= O}{}^{\mathrm{x}}{}_{\mathrm{o}}\text{+ 2Fe}{}^{\mathrm{·}}{}_{\mathrm{Fe}}$

and K_i for the reaction

$\text{2Fe}{}^{\mathrm{x}}{}_{\mathrm{Fe}}\text{= Fe}{}^{\mathrm{\prime }}{}_{\mathrm{Fe}}\text{+ Fe}{}^{\mathrm{·}}{}_{\mathrm{Fe·}}$

Using these constants, the defect concentrations were calculated as functions of P_O2, temperature, and composition x. The present results are discussed with respect to previously reported results of conductivity measurements.     

16.

Kinetics and mechanism of the interaction of hexaaquochromium(III) with octacyanomolybdate(IV) ions     

S.I. Ali  Zakir Murtaza 《Polyhedron》1985,4(3):463-466

The kinetics of the interaction of hexaaquochromium(III) ion with potassium octacyanomolybdate(IV) have been studied using conductance and spectrophotometric data. The mechanism of the reaction is discussed and the effect of H⁺ ion and the ionic strength on the rate of the reaction determined. The reaction is found to be pseudo-first order with respect to potassium octacyanomolybdate(IV) and inverse first order with [H₃O⁺]. The rate of the reaction increases with increase in ionic strength and temperature. Activation parameters have been calculated using the Arrhenius equation and have the values ΔE^* = 1.3 × 10² kJ mol^?1, ΔH^* = 129 kJ mol^?1, ΔS^* = ?315 e.u., ΔF^* = 2.3 × 10² kJ and A = 1.5 × 10^?3. The mechanism proposed is based on ion-pair formation and the rate equation obtained is given by: k_obs=$\text{[}{}_{\mathrm{kK}}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k′K′k}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k}{}_{\mathrm{<mtext>h</mtext>}}\text{+[}\text{K}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{K′}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}$     

17.

An analysis of the rare earth contribution to the magnetic anisotropy in RCo5 and R2Co17 compounds     

J.E. Greedan  V.U.S. Rao 《Journal of solid state chemistry》1973,6(3):387-395

An attempt has been made to treat the rare earth contribution to the magnetocrystalline anisotropy in RCo₅ and R₂Co₁₇ compounds with a single ion model using a Hamiltonian of the form:

$\text{H=}\text{B}{}_2{}^0\text{O}{}_2{}^0\text{+gμ}{}_{\mathrm{B}}\text{J·H}{}_{\mathrm{<mtext>ex</mtext>}}$

H_ex is regarded as arising mainly from the cobalt sublattice. Eigenvalues and eigenfunctions for the above Hamiltonian were obtained when the exchange field is perpendicular to the c-axis and compared with those when it is parallel to the c-axis. For values of H_ex estimated from experiment it is found that the sign of B₂⁰ determines the direction preference of the rare earth sublattice magnetization. Comparison of theory with experiment shows that the correct sign of B₂⁰ can be predicted on the point charge model considering only the effect of rare earth nearest neighbors. The calculations also predict that the quantity |K_1R(0) + K_2R(0)| is nearly equal to the crystal field overall splitting (CFOAS) determined in the absence of exchange and is independent of the magnitude of the exchange field, provided that the exchange field is sufficiently large. The temperature dependence of |K_1R + K_2R| has also been calculated and found to agree semiquantitatively with available experimental results.     

18.

Unusual effects of anisotropic bonding in Cu(II) and Ni(II) oxides with K2NiF4 structure     

K.K. Singh  P. Ganguly  J.B. Goodenough 《Journal of solid state chemistry》1984,52(3):254-273

Geometric constraints present in A₂BO₄ compounds with the tetragonal-T structure of K₂NiF₄ impose a strong pressure on the BO_IIB bonds and a stretching of the AO_IA bonds in the basal planes if the tolerance factor is $\text{t ?}\text{R}{}_{\mathrm{<mtext>AO</mtext>}}\text{√2 R}{}_{\mathrm{<mtext>BO</mtext>}}\text{< 1}$, where R_AO and R_BO are the sums of the AO and BO ionic radii. The tetragonal-T phase of La₂NiO₄ becomes monoclinic for Pr₂NiO₄, orthorhombic for La₂CuO₄, and tetragonal-T′ for Pr₂CuO₄. The atomic displacements in these distorted phases are discussed and rationalized in terms of the chemistry of the various compounds. The strong pressure on the BO_IIB bonds produces itinerant bands and a relative stabilization of localized d_z² orbitals. Magnetic susceptibility and transport data reveal an intersection of the Fermi energy with the d²_z² levels for half the copper ions in La₂CuO₄; this intersection is responsible for an intrinsic localized moment associated with a configuration fluctuation; below 200 K the localized moment smoothly vanishes with decreasing temperature as the d²_z² level becomes filled. In La₂NiO₄, the localized moments for half-filled d_z² orbitals induce strong correlations among the electrons above $\text{T}{}_{\mathrm{<mtext>d</mtext>}}\text{? 200}\text{K}$; at lower temperatures the electrons appear to contribute nothing to the magnetic susceptibility, which obeys a Curie-Weiss law giving a μ_eff corresponding to $\text{S =}\text{1}\text{2}$, but shows no magnetic order to lowest temperatures. These surprising results are verified by comparison with the mixed systems La₂Ni_1?xCu_xO₄ and La_2?2xSr_2xNi_1?xTi_xO₄. The onset of a charge-density wave below 200 K is proposed for both La₂CuO₄ and La₂NiO₄, but the atomic displacements would be short-range cooperative in mixed systems. The semiconductor-metallic transitions observed in several systems are found in many cases to obey the relation $\text{E}{}_{\mathrm{<mtext>a</mtext>}}\text{? kT}{}_{\mathrm{<mtext>min</mtext>}}$, where $\text{? = ?}{}_0\text{exp}\text{(}\text{?E}{}_{\mathrm{<mtext>a</mtext>}}\text{kT}\text{)}$ and T_min is the temperature of minimum resistivity ?. This relation is interpreted in terms of a diffusive charge-carrier mobility with $\text{E}{}_{\mathrm{<mtext>a</mtext>}}\text{? ΔH}{}_{\mathrm{<mtext>m</mtext>}}\text{? kT}$ at T = T_min.     

19.

A theory of viscosity of dilute and moderately concentrated polymer solutions     

V.P. Budtov 《European Polymer Journal》1981,17(2):191-195

A model theory of viscosity η for moderately concentrated polymer solutions is based on the assumption of a “local viscosity” effect and intermolecular hydrodynamic and thermodynamic interactions. It is shown that η is given by

$\text{η = η}{}_{\mathrm{o}}\text{{1 + γc[η]}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{·}\text{exp}\text{H}{}_{\mathrm{o}}\text{RT}\text{aø}\text{1 ? aø}$

where γ is 0–0.4 and depends on the quality of the solvent, a varies between 0,4 and 0.8 and depends on the fraction of the “free volume” of the systems, H₀ is the activation energy of the solvent and π is the polymer volume concentration. The dependence of η and “activation energy” of π and T for various molecular weights and qualities of solvents is described quantitatively. Anomalous dependences of [η] and of η on M for low polymer are obtained. An expression for η is proposed:

$\text{η}\text{η}{}_{\mathrm{o}}{}^{\mathrm{<mtext>1\; ?\; 2</mtext><mtext>K</mtext>}}\text{= {1 + (1 ? 2K)c[η]}F(π)}$

where K is the Huggins-Martin coefficient and F(π) = 1 for most solutions when T is > T_g. For poor solvents the H vs c curve (where H is the activation energy of η of solution) has a minimum value at moderate concentrations. For good solvents, H depends slightly on the molecular weight according to an empirical equation:

$\text{H = H}{}_{\mathrm{o}}\text{+}\text{660}\text{α}{}^3\text{1}\text{n}\text{η}\text{η}{}_{\mathrm{o}}$

Expressions are given from the viscosities of solutions of miscible and also solutions of immiscible polymers.     

20.

Thermochemical determination of the enthalpies of combustion and formation of fullerene C70     

《The Journal of chemical thermodynamics》2003,35(1):189-193

     

	$\text{S}{}^0\text{/}\text{cal}{}_{\mathrm{th}}\text{K}{}^{\mathrm{?1}}\text{mol}{}^{\mathrm{?1}}$	$\text{ΔH}{}_{\mathrm{f}}{}^0\text{/kcal}{}_{\mathrm{th}}\text{mol}{}^{\mathrm{?1}}$	$\text{ΔG}{}_{\mathrm{f}}{}^0\text{/kcal}{}_{\mathrm{th}}\text{mol}{}^{\mathrm{?1}}$
CrO42?(aq)	(13.8 ± 0.5)	?(210.93 ± 0.45)	?(174.8 ± 0.5)
HCrO4?(aq)	(46.6 ± 1.8)	?(210.0 ± 0.7)	?(183.7 ± 0.5)
Cr2O72?(aq)	(67.4 ± 3.9)	?(356.5 ± 1.5)	?(312.8 ± 1.0)

Cesium chromate,Cs2CrO4: heat capacity and thermodynamic properties from 5 to 350 K

The heat capacity of a sample of Cs₂CrO₄ was determined in the temperature range 5 to 350 K by aneroid adiabatic calorimetry. The heat capacity at constant pressure C_p^o(298.15 K), the entropy S^o(298.15 K), the enthalpy {H^o(298.15 K) - H^o(0)} and the function $\text{? {G}{}^{\mathrm{o}}\text{(298.15}\text{K}\text{) - H}{}^{\mathrm{o}}\text{(0)}}\text{298.15}\text{K}$ were found to be (146.06 ± 0.15) J K^?1 mol^?1, (228.59 ± 0.23) J K^?1 mol^?1, (30161 ± 30) J mol^?1, and (127.43 ± 0.13) J K^?1 mol^?1, respectively. The heat capacity C_p^o(298.15 K) and entropy S^o(298.15 K) and entropy S^o(298.15 K) of Rb₂CrO₄ are estimated to be (146.0 ± 1.0) J K^?1 mol^?1 and (217.6 ± 3.0) J K^?1 mol^?1, respectively.     

Mutual solubility of n-butanol + water under high pressures

The mutual solubilities of {xCH₃CH₂CH₂CH₂OH+(1-x)H₂O} have been determined over the temperature range 302.95 to 397.75 K at pressures up to 2450 atm. An increase in temperature and pressure results in a contraction of the immiscibility region. The results obtained for the critical solution properties are: T_o(U.C.S.T.) = 397.85 K and x_o = 0.110 at 1 atm; $\text{(}\text{dT}{}_{\mathrm{o}}\text{d}\text{p}\text{) = ?(12.0±0.5)×10}{}^{\mathrm{?3}}\text{K atm}{}^{\mathrm{?1}}$ at p < 400 atm and $\text{(}\text{dT}{}_{\mathrm{o}}\text{d}\text{p}\text{) = ?(7.0±0.7)×10}{}^{\mathrm{?3}}\text{K atm}{}^{\mathrm{?1}}$ at 800 atm < p < 2500 atm; $\text{(}\text{dx}{}_{\mathrm{o}}\text{d}\text{T}\text{) = ?(4.0±0.5)×10}{}^{\mathrm{?4}}\text{K}{}^{\mathrm{?1}}$.     

Synthesis of homoleptic tris(organo-chelate)iridium(III) complexes by spontaneous ortho-metallation of electronrich olefin-derived N,N′-diarylcarbene ligands and the X-ray structures of fac-[Ir{CN(C6H4Me-p) (CH2)2NC6H3Me-p}3] and mer-Ir{CN(C6H4Me-p)(CH2)2NC6H3Me-p}2 {CN(C6H4Me-p)(CH2)2NC6H4Me-p}Cl (a product of HCl cleavage)

Treatment of [{Ir(COD)(μ-Cl)}₂] with excess of the electron-rich olefin [$\text{CN(Ar)(CH}{}_2\text{)}{}_2\text{N}$Ar]₂ (abbreviated as (L^Ar)₂, Ar = C₆H₄Me-p or C₆H₄OMe-p) affords the ortho-metallated tricycle [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₃], which for Ar = C₆H₄Me-p (Ia) with HCL yields [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₂(L^Ar)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir?C(o-aryl) contact (2;52(1) Å) involving the “free” L^Ar which compares with an IrC(o-aryl) distance of 2.09(3) Å in Ia or 2.07(3) Å in the ortho-metallated L^Ar ligand of complex IV.     

Determination of the vapour pressures of o-, m-, and p-dinitrobenzene by the torsion-effusion method

The vaporization of o-, m-, and p-dinitrobenzenes was investigated by means of the torsion-effusion method and the selected equations for vapour pressure p as a function of temperature T are:

$\text{o-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(7.03±0.34)?(4270±120)}\text{K}\text{T}\text{,m-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(7.66±0.28)?(4400±100)}\text{K}\text{T}\text{,p-dinitrobenzene: log}{}_{10}\text{(}\text{p}\text{atm}\text{)=(8.34±0.34)?(4860±120)}\text{K}\text{T}$

The sublimation enthalpies ΔH^o(o-, 298.15 K) = (21.0 ± 0.5) kcal_th mol^?1, ΔH^o(m-, 298.15 K) = (20.8 ± 0.2) kcal_th mol^?1, and ΔH^o(p-, 298.15 K) = (23.0 ± 0.6) kcal_th mol^?1, are also derived by means of the second- and third-law treatments of the results.     

Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen XX. Darstellung,eigenschaften und kristallstruktur von λ4-thia-λ5-phospha-h2-metallabicyclo[2.2.1]heptadienen und ihre verwendung zur synthese von metallorganischen und organischen verbindungen

The novel λ⁴-thia-λ⁵-phospha-h²-manganabicyclo[2.2.1]heptadienes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{PR}{}^1{}_2\text{S}$] (R¹ = CH₃, C₆H₅; R² = CO₂CH₃, CO₂C₂H₅, CO₂C₆H₁₁) are formed by action of the activated alkynes R²C  CR² on the heterocycles [(OC)₄MnPR¹₂S]₂ via the isolable, five-membered heterometallacyclopentadienes (OC)₄$\text{MnSPR}{}^1{}_2\text{C(R}{}^2\text{)C}$(R²). The compound with R¹ = CH₃ and R² = CO₂CH₃ crystallizes in the triclinic space group P$\text{1}$ with Z = 2 and separates quantitatively the thiophene derivative $\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{S}$ under CO pressure or by reaction with (NH₄)₂Ce(NO₃)₆. The use of various acetylenes and of acetylenes with different alkyl groups yields the unsymmetric substituted manganabicycloheptadienes (OC)₃Mn[$\text{CR}{}^4\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P(CH}{}_3\text{)}{}_2\text{S}$] (R² = CO₂CH₃, R³ = R⁴ = CO₂C₂H₅; R² = R⁴ = CO₂CH₃, R³ = H). With propionic acid methylester the alkyne insertion proceeds regiospecifically. With Raney nickel selective S elimination under ring contraction and formation of the λ⁴-phospha-h²-manganabicyclo[2.1.1]hexenes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$R¹₂] (R¹ = CH₃: R² = R³ = CO₂CH₃, CO₂C₂H₅; R² = CO₂CH₃, R³ = H; R¹ = C₆H₅: R² = R³ = CO₂C₂H₅) occurs. (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$(CH₃)₂] (R² = R³ = CO₂CH₃) crystallizes in the monoclinic space group P2₁/m with Z = 2. The IR and NMR spectra of the heterocycles are discussed in detail.     

Thermophysics of alkali and related azides II. Heat capacities of potassium,rubidium, cesium,and thallium azides from 5 to 350 K

The heat capacities of potassium, rubidium, cesium, and thallium azides were determined from 5 to 350 K by adiabatic calorimetry. Although the alkali-metal azides studied in this work exhibited no thermal anomalies over the temperature range studied, thallium azide has a bifurcated anomaly with two maxima at (233.0±0.1) K and (242.04±0.02) K. The associated excess entropy was 0.90 cal_th K^?1 mol^?1. The thermal properties of the azides and the corresponding structurally similar hydrogen difluorides are nearly identical. Both have linear symmetrical anions. However, thallium azide shows a solid-solid phase transition not exhibited by thallium hydrogen difluoride. At 298.15 K the values of C_p^o, S^o, and $\text{?{G}{}^{\mathrm{o}}\text{(T)?H}{}^{\mathrm{o}}\text{(0)}}\text{T}$, respectively, are 18.38, 24.86, and 12.676 cal_th K^?1 mol^?1 for potassium azide; 19.09, 28.78, and 15.58 cal_th K^?1 mol^?1 for rubidium azide; 19.89, 32.11, and 18.17 cal_th K^?1 mol^?1 for cesium azide; and 19.26, 32.09, and 18.69 cal_th K^?1 mol^?1 for thallium azide. Heat capacities at constant volume for KN₃ were deduced from infrared and Raman data.     

Extraction of indium(III) from chloride medium with 1-phenyl-3-methyl-4-acylpyrazol-5-ones. Synergic effect with high molecular weight ammonium salts.

The extraction of In(III) from 1M (Na,H)(Cl,ClO₄) media with 4-acylpyrazol-5-ones (HL) in toluene at 25°C is described by equilibria In ³⁺ + 3 $\text{HL}$ ? $\text{InL}{}_3$ + 3 H⁺ (log K = 1.48, 1.03, 0.87 with acyl = benzoyl, lauroyl, 2-thenoyl), InCl ²⁺ + 2 $\text{HL}$ ? $\text{InClL}{}_2$ + 2 H⁺ (log K = 0.26, ?0.45, ?0.35 respectively) and In³⁺ + m Cl^? ? InCl_m^(3-m)+ (log β_m available from literature). The extraction from 1M (Na,H)(Cl,NO₃) medium is enhanced by addition of aliquat (TOMA⁺,Cl^?) and the following synergic equilibrium takes place : $\text{InCl}{}_2$ + $\text{(TOMA}{}^{\mathrm{+}}$,Cl^?) ? $\text{(TOMA}{}^{\mathrm{+}}$, InCl₂L₂^? (log K = 5.49, 5.25, 5.21 respectively). Cl^? of (TOMA⁺,Cl^?) is exchanged by NO₃^? with the equilibrium constant log K = 1.50. If (TOMA⁺,Cl^?) is replaced by tri-n-octylammonium chloride, the synergic effect is largely reduced (log K = 4.17 with acyl = benzoyl). The extraction from chloride solutions containing ClO₄^? remains unchanged by addition of ammonium salts.     

Etude comparative des structures type K4NiF4 et pérovskite par la méthode des invariants

The study of K₂NiF₄ and perovskite structure type by the “method of invariants” leads to the relationship: $\text{(A-X)}{}_9\text{2}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? (A-X)}{}_{12}\text{=}\text{constant}$, where (A-X)₉ and (A-X)₁₂ are the invariant values associated with cation A in coordination number 9 and 12. In the case where A = K⁺ and X = F^?, we propose the relationship:

$\text{(K}{}^{\mathrm{+}}\text{?F)}{}_{\mathrm{R}}\text{= 2.832 R}{}^{\mathrm{<mtext>1</mtext><mtext>11.4</mtext>}}$

where R is the coordination number.     

Thermodynamic properties of two metal-rich tantalum sulfides: Ta2S and Ta6S

The incongruent vaporization reactions of Ta₂S and Ta₆S have been investigated by mass-loss effusion in the temperature range 1576 to 1902 K. By extrapolation of P_S(obs) to equilibrium the enthalpies of the reactions $\text{3}\text{2}\text{Ta}{}_2\text{S(s)}\text{=}\text{1}\text{2}\text{Ta}{}_6\text{S(s) + S(g)}$ and Ta₆S = 6 Ta(s) + S(g) were found to be $\text{ΔH}{}^0{}_{298}\text{R}\text{= 53.0(0.3) · 10}{}^3\text{K}$ and $\text{ΔH}{}^0{}_{298}\text{R}\text{= 58.1(0.4) · 10}{}^3\text{K}$, respectively. Comparison between the above values, determined by a 2nd law treatment, and 3rd law values was used to derive fef (“free energy function”) values for Ta and S in the compounds. These postulated fef's, which apply only to the elements as present in the compounds measured, are compared to tabulated quantities for the pure solid elements to provide a criterion for 2nd and 3rd law evaluation.     

Standard enthalpy of solution and formation of cesium chromate. Derived thermodynamic properties of the aqueous chromate,bichromate, and dichromate ions,alkali metal and alkaline earth chromates,and lead chromate

Calorimetric measurements of the enthalpy of solution of cesium chromate gave ΔH_soln = (7622 ± 24) cal_th mol^?1 for a dilution of Cs₂CrO₄·21128H₂O. This result, along with the enthalpy of dilution gave the standard enthalpy of solution, ΔH_soln^o = (7512 ± 31) cal_th mol^?1, whence the standard enthalpy of formation, ΔH_f⁰(Cs₂CrO₄, c, 298.15 K), was calculated to be ?(341.78 ± 0.46) kcal_th mol^?1. Recomputed thermodynamic data for the formation of the other alkali metal chromates have been tabulated. From their solubilities and enthalpies of solution, the standard entropies, S⁰(298 K), of BaCrO₄ and PbCrO₄ were estimated to be (38.9 ± 0.9) and (43.7 ± 1.2) cal_th K^?1 mol^?1, respectively. There is evidence that ΔH_f⁰(SrCrO₄, c, 298.15 K) may be in error. Thermochemical, solubility, and equilibrium data, have been combined to update the thermodynamic properties of the aqueous chromate (CrO₄^2?), bichromate (HCrO₄^?), and dichromate (Cr₂O₇^2?) ions. The new values at 298.15 K are as follows:

Dilute solution properties of poly(N-vinyl-3,6-dibromo carbazole)—III. Phase equilibrium studies

The phase relationships of poly(N-vinyl-3,6-dibromo carbazole) (PVK-3, 6-Br₂) were examined for four solvents, viz, o-chlorophenol, p-chloro-m-cresol, o-dichlorobenzene and bromobenzene. Upper critical solution temperatures (UCST) have been determined for solutions of PVK-3,6-Br, fractions in o-chlorophenol and p-chloro-m-cresol over the molecular weight range $\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{× 10}{}^{\mathrm{?4}}\text{= 125.0}\text{to}\text{4.8}$. The Flory temperature, θ, obtained from UCST for the PVK-3,6-Br₂/o-chlorophenol and PVK-3,6-Br₂/p-chloro-m-cresol systems are 66.0 and 112.9°C, respectively. The θ-temperatures were checked against molecular weight and viscosity data to determine the Mark-Houwink equations for these two theta solvents, with satisfactory agreement. The relations are

$\text{[ν] = 27.5}{}_4\text{× 10}{}^{\mathrm{?10}}\text{×}\text{M}{}^{0.50}{}_{\mathrm{<mtext>w</mtext>}}\text{(o-}\text{chlorophenol}\text{, 60.0°}\text{C}$

$\text{[ν] = 30.2}{}_4\text{× 10}{}^{\mathrm{?10}}\text{×}\text{M}{}^{0.50}{}_{\mathrm{<mtext>w</mtext>}}\text{(p-}\text{chloro}\text{-m}\text{cresol}\text{, 112.9°}\text{C}$

The characteristic ratio C_∞ = 〈R²〉₀/nl² was found to be 16.6 in o-chlorophenol at 60.0°C and 17.6 in p-chloro-m-cresol at 112.9°C. The value of the characteristic ratio C_∞ of PVK-3,6-Br₂ is of the same order of that for poly(N-vinyl carbazole). This indicates that the bromine atoms at the 3 and 6 (meta) positions have only an inappreciable effect on the hindering potential for rotation about the CC bond. This agreement of C_∞ for both polymers may also be taken as indicating that the effect of interaction between polar groups at the m-position on the hindering potential for rotation is small. The phase diagrams of PVK-3,6-Br₂ obtained in o-dichlorobenzene and bromobenzene seem to be characteristic of organized phase structures such as those found in systems exhibiting thermoreversible gelation. Light scattering measurement on PVK-3,6-Br₂ dissolved in o-dichlorobenzene, a gelation promoting solvent, and tetrahydrofuran, a very good solvent, strongly indicate that the macromolecular species in o-dichlorobenzene contain some extent supermolecular structures (aggregates, association of chain segments, etc.). These characteristic structures of PVK-3,6-Br₂ in o-dichlorobenzene and bromobenzene at 25°C are also characterized by high values of the Huggins' constant k′; for tetrahydrofuran solutions, the k′ values were in the range normally found for many good solvent-polymer systems.     

Cyclopentadienyl-ruthenium and -osmium chemistry: XXIV. Some complexes containing the olefinic tertiary phosphine 2-CH2CHC6H4PPh2 (sp): X-ray structures of one isomer of OsBr(sp)(η-C5H5), and of Ru(η3-S2CCHMeC6H4PPh2-2)(η-C5H5), containing an η3-dithiocarboxylato group

Reactions between MX(PPh₃)₂(η-C₅H₅) (M = Ru, X = Cl; M = Os, X = Br) and 2-CH₂CHC₆H₄PPh₂ afford $\text{MX(η}{}^2\text{-CH}{}_2\text{CHC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅); the Os complex is obtained in two isomeric forms. The X-ray structure of the major isomer shows the CC double bond (OsC, 2.214, 2.195 Å; CC, 1.57 Å) is almost coplanar with the OsBr vector, with the terminal C cis to Br; the minor isomer is assumed to have the alternative, more sterically congested conformation, with the β-C cis to Br. The chlororuthenium complex reacts with NaOMe/MeOH to give the corresponding hydrido complex, which also exists as two isomers in solution; reaction of this complex with CS₂ gives the expected dithio acid derivative $\text{Ru(S}{}_2\text{CCHMeC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅), together with small amounts of a complex assumed to be $\text{Ru[S}{}_2\text{C(CH}{}_2\text{)}{}_2\text{C}{}_6\text{H}{}_4\text{P}$Ph₂](η-C₅H₅). The X-ray structure of the major product reveals an unusual η³-S₂C mode of coordination of the dithio acid fragment (RuS, 2.418, 2.426(1) Å; RuC 2.175(4) Å). Crystals of OsBr(η²-CH₂CHC₆H₄P)Ph₂)( η-C₅H₅) are monoclinic, space group P2₁/n, with a 12.696(2), b 21.719(6), c 15.929(3) Å, β 79.77(2)°, Z = 8; 2867 data (I > 2.5σ(I)) were refined to R = 0.040, R_w = 0.044. Crystals of $\text{Ru(η}{}^3\text{-S}{}_2\text{CCHMeC}{}_6\text{H}{}_4\text{P}$Ph₂)(η-C₅H₅) are orthorhombic, space group Pbca, with a 8.921(2), b 15.982(9), c 32.216(5) Å, Z = 8; 1685 data (I > 2.5σ(I)) were refined to R = 0.027, R_w = 0.030.     

Nonstoichiometry and defect structure of the perovskite-type oxides La1−xSrxFeO3−°

In order to elucidate the defect structure of the perovskite-type oxide solid solution La_1?xSr_xFeO_3?δ (x = 0.0, 0.1, 0.25, 0.4, and 0.6), the nonstoichiometry, δ, was measured as a function of oxygen partial pressure, P_O2, at temperatures up to 1200°C by means of the thermogravimetric method. Below 200°C and in an atmosphere of P_O2 ≥ 0.13 atm, δ in La_1?xSr_xFeO_3?δ was found to be close to 0. With decreasing log P_O2, δ increased and asymptotically reached $\text{x}\text{2}$. The value corresponding to $\text{δ =}\text{x}\text{2}$ was about ?10 at 1000°C. With further decrease in log P_O2, δ slightly increased. For LaFeO_3?δ, the observed δ values were as small as <0.015. It was found that the relation between δ and log P_O2 is interpreted on the basis of the defect equilibrium among Sr′_La (or V?_La for the case of LaFeO_3?δ), V^··_O, Fe′_Fe, and Fe^·_Fe. Calculations were made for the equilibrium constants K_ox of the reaction

$\text{1}\text{2}\text{O}{}_2\text{(g) + V}{}^{\mathrm{··}}{}_{\mathrm{o}}\text{+ 2Fe}{}^{\mathrm{x}}{}_{\mathrm{Fe}}\text{= O}{}^{\mathrm{x}}{}_{\mathrm{o}}\text{+ 2Fe}{}^{\mathrm{·}}{}_{\mathrm{Fe}}$

and K_i for the reaction

$\text{2Fe}{}^{\mathrm{x}}{}_{\mathrm{Fe}}\text{= Fe}{}^{\mathrm{\prime }}{}_{\mathrm{Fe}}\text{+ Fe}{}^{\mathrm{·}}{}_{\mathrm{Fe·}}$

Using these constants, the defect concentrations were calculated as functions of P_O2, temperature, and composition x. The present results are discussed with respect to previously reported results of conductivity measurements.     

Kinetics and mechanism of the interaction of hexaaquochromium(III) with octacyanomolybdate(IV) ions

The kinetics of the interaction of hexaaquochromium(III) ion with potassium octacyanomolybdate(IV) have been studied using conductance and spectrophotometric data. The mechanism of the reaction is discussed and the effect of H⁺ ion and the ionic strength on the rate of the reaction determined. The reaction is found to be pseudo-first order with respect to potassium octacyanomolybdate(IV) and inverse first order with [H₃O⁺]. The rate of the reaction increases with increase in ionic strength and temperature. Activation parameters have been calculated using the Arrhenius equation and have the values ΔE^* = 1.3 × 10² kJ mol^?1, ΔH^* = 129 kJ mol^?1, ΔS^* = ?315 e.u., ΔF^* = 2.3 × 10² kJ and A = 1.5 × 10^?3. The mechanism proposed is based on ion-pair formation and the rate equation obtained is given by: k_obs=$\text{[}{}_{\mathrm{kK}}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k′K′k}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k}{}_{\mathrm{<mtext>h</mtext>}}\text{+[}\text{K}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{K′}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}$     

An analysis of the rare earth contribution to the magnetic anisotropy in RCo5 and R2Co17 compounds

An attempt has been made to treat the rare earth contribution to the magnetocrystalline anisotropy in RCo₅ and R₂Co₁₇ compounds with a single ion model using a Hamiltonian of the form:

$\text{H=}\text{B}{}_2{}^0\text{O}{}_2{}^0\text{+gμ}{}_{\mathrm{B}}\text{J·H}{}_{\mathrm{<mtext>ex</mtext>}}$

H_ex is regarded as arising mainly from the cobalt sublattice. Eigenvalues and eigenfunctions for the above Hamiltonian were obtained when the exchange field is perpendicular to the c-axis and compared with those when it is parallel to the c-axis. For values of H_ex estimated from experiment it is found that the sign of B₂⁰ determines the direction preference of the rare earth sublattice magnetization. Comparison of theory with experiment shows that the correct sign of B₂⁰ can be predicted on the point charge model considering only the effect of rare earth nearest neighbors. The calculations also predict that the quantity |K_1R(0) + K_2R(0)| is nearly equal to the crystal field overall splitting (CFOAS) determined in the absence of exchange and is independent of the magnitude of the exchange field, provided that the exchange field is sufficiently large. The temperature dependence of |K_1R + K_2R| has also been calculated and found to agree semiquantitatively with available experimental results.     

Unusual effects of anisotropic bonding in Cu(II) and Ni(II) oxides with K2NiF4 structure

Geometric constraints present in A₂BO₄ compounds with the tetragonal-T structure of K₂NiF₄ impose a strong pressure on the BO_IIB bonds and a stretching of the AO_IA bonds in the basal planes if the tolerance factor is $\text{t ?}\text{R}{}_{\mathrm{<mtext>AO</mtext>}}\text{√2 R}{}_{\mathrm{<mtext>BO</mtext>}}\text{< 1}$, where R_AO and R_BO are the sums of the AO and BO ionic radii. The tetragonal-T phase of La₂NiO₄ becomes monoclinic for Pr₂NiO₄, orthorhombic for La₂CuO₄, and tetragonal-T′ for Pr₂CuO₄. The atomic displacements in these distorted phases are discussed and rationalized in terms of the chemistry of the various compounds. The strong pressure on the BO_IIB bonds produces itinerant bands and a relative stabilization of localized d_z² orbitals. Magnetic susceptibility and transport data reveal an intersection of the Fermi energy with the d²_z² levels for half the copper ions in La₂CuO₄; this intersection is responsible for an intrinsic localized moment associated with a configuration fluctuation; below 200 K the localized moment smoothly vanishes with decreasing temperature as the d²_z² level becomes filled. In La₂NiO₄, the localized moments for half-filled d_z² orbitals induce strong correlations among the electrons above $\text{T}{}_{\mathrm{<mtext>d</mtext>}}\text{? 200}\text{K}$; at lower temperatures the electrons appear to contribute nothing to the magnetic susceptibility, which obeys a Curie-Weiss law giving a μ_eff corresponding to $\text{S =}\text{1}\text{2}$, but shows no magnetic order to lowest temperatures. These surprising results are verified by comparison with the mixed systems La₂Ni_1?xCu_xO₄ and La_2?2xSr_2xNi_1?xTi_xO₄. The onset of a charge-density wave below 200 K is proposed for both La₂CuO₄ and La₂NiO₄, but the atomic displacements would be short-range cooperative in mixed systems. The semiconductor-metallic transitions observed in several systems are found in many cases to obey the relation $\text{E}{}_{\mathrm{<mtext>a</mtext>}}\text{? kT}{}_{\mathrm{<mtext>min</mtext>}}$, where $\text{? = ?}{}_0\text{exp}\text{(}\text{?E}{}_{\mathrm{<mtext>a</mtext>}}\text{kT}\text{)}$ and T_min is the temperature of minimum resistivity ?. This relation is interpreted in terms of a diffusive charge-carrier mobility with $\text{E}{}_{\mathrm{<mtext>a</mtext>}}\text{? ΔH}{}_{\mathrm{<mtext>m</mtext>}}\text{? kT}$ at T = T_min.     

A theory of viscosity of dilute and moderately concentrated polymer solutions

A model theory of viscosity η for moderately concentrated polymer solutions is based on the assumption of a “local viscosity” effect and intermolecular hydrodynamic and thermodynamic interactions. It is shown that η is given by

$\text{η = η}{}_{\mathrm{o}}\text{{1 + γc[η]}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{·}\text{exp}\text{H}{}_{\mathrm{o}}\text{RT}\text{aø}\text{1 ? aø}$

where γ is 0–0.4 and depends on the quality of the solvent, a varies between 0,4 and 0.8 and depends on the fraction of the “free volume” of the systems, H₀ is the activation energy of the solvent and π is the polymer volume concentration. The dependence of η and “activation energy” of π and T for various molecular weights and qualities of solvents is described quantitatively. Anomalous dependences of [η] and of η on M for low polymer are obtained. An expression for η is proposed:

$\text{η}\text{η}{}_{\mathrm{o}}{}^{\mathrm{<mtext>1\; ?\; 2</mtext><mtext>K</mtext>}}\text{= {1 + (1 ? 2K)c[η]}F(π)}$

where K is the Huggins-Martin coefficient and F(π) = 1 for most solutions when T is > T_g. For poor solvents the H vs c curve (where H is the activation energy of η of solution) has a minimum value at moderate concentrations. For good solvents, H depends slightly on the molecular weight according to an empirical equation:

$\text{H = H}{}_{\mathrm{o}}\text{+}\text{660}\text{α}{}^3\text{1}\text{n}\text{η}\text{η}{}_{\mathrm{o}}$

Expressions are given from the viscosities of solutions of miscible and also solutions of immiscible polymers.