Fonctions autocohérentes et intégrales radiales pour les ions de la série du fer

The radial integrals 3d¦r ^k ¦3d, k=–3, –1, 2, 4 and 4p¦r ^k ¦3d, k= 1, 3 for first-row transition-metal ions have been computed from analytical self-consistent field wave functions. The expressions 4p¦r ^k ¦3d allow to compute the oscillator strengths of dipolar electric transitions for an trapped in a crystalline matrix iron group ion. Les intégrales 3d¦r ^k ¦3d, k=–3, –1, 2, 4 et 4p¦r ^k ¦3d, k=1, 3, relatives aux ions de la première série de transition, sont calculées à l'aide de fonctions radiales _3d et _4p , autocohérentes. Les expressions 4p¦r ^k ¦3d permettent d'évaluer les forces d'oscillateur de transitions dipolaires électriques relatives à un ion du groupe du fer engagé dans une matrice cristalline.     

Spectra and structure of small ring compounds. Part L VIII: Structural parameters for chlorocyclobutane from combined microwave data and ab initio calculations

The structural parameters of chlorocyclobutane,c-C₄H₇Cl, have been obtained fromab initio Hartree-Fock calculations employing the 6–31G^* basis set for both the more stable equatorial and the high energy axial conformers. The determined carbonhydrogen distances were adjusted by 0.010 Å and held fixed while a weighted least-squares adjust was used to obtain all of the heavy atom parameters for the equatorial conformer by fitting the rotational constants of nine isotopic species. The determinedr ₀ parameters are:r(C - C) = 1.535(8) År(C - C) = 1.548(3) År(C - Cl) = 1.788(9) Å CCC, - CL = 132.0(2)°; CCC, = 89.7(6)°; CCC, = 87.1(2)°, and CCC, = 88.7(2)°. These results are compared to the calculated values as well as those obtained earlier from electron diffraction and microwave studies.For Part LVII, seeJ. Raman Spectrosc.,1990,21, 591.Taken in part from the thesis of M. J. Lee which will be submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree.     

Molecular structure and conformational composition of 1-Chlorobutane, 1-Bromobutane,and 1-Iodobutane as determined by gas-phase electron diffraction and ab initio calculations

Gas-phase electron diffraction (ED), together with ab initio molecular orbital calculations, have been used to determine the structure and conformational composition of 1-chlorobutane, 1-bromobutane, and 1-iodobutane. These molecules may in principle exist as mixtures of five different conformers, but only three or four of these were observed in gas phase at temperatures of the ED experiments, 18C, 18C, and 23C, respectively. The observed conformational compositions (1-chlorobutane, 1-bromobutane, and 1-iodobutane) were AA (13 ± 12%, 21 ± 14%, 19 ± 17%), GA (60±13%, 33±32%, 17±31%), AG (12±16%, 8±12%, <1%), and GG (12 ±16%, 38± 34%, 64±31%). A and G denotesanti andgauche positions for the X-C₁-C₂-C₃ (X=Cl, Br, I), and the C₁-C₂-C₃-C₄ torsion angles. The results for the most important distances (r _g) and angles () from the combined ED/ab initio study for the GA conformer of 1-chlorobutane, with estimated 2 uncertainties, arer(C₁-C₂)=1.519(3)å,r (C₂-C₃)=1.530(3) å,r (C₃-C₄)=1.543(3) å,r (C₁-Cl)=1.800(4) å, <C₁C₂C₃=114.3(6), <C₂C₃C₄=112.0(6), <CCCl=112.3(5). The results for the GA conformer of 1-bromobutane arer (C₁-C₂)=1.513(4) å,r (C₂-C₃)=1.526(4) å,r (C₃-C₄)=1.540(4) å,r(C₁-Br)=1.959(8) å, <C₁C₂C₃=115.3(11), <C₂C₃C₄=112.8(11),<CCBr=112.1(14). The results for 1-chlorobutane and 1-bromobutane are compared with those from earlier electron diffraction investigations. The results for the GA conformer of 1-iodobutane arer (C₁-C₂)=1.506(5) å,r (C₂-C₃)=1.518(5) å,r (C₃-C₄)=1.535(5) å,r (C₁-I)=2.133(11) å, <C₁C₂C₃=116.8(15), <C₂C₃C₄=115.3(15), <CCI=110.2(14). Differences in length between the different C-H bonds in each molecule, between the different C-C bonds, between the different CCH angles, and between the different CCC angles were kept constant at the values obtained from the ab initio calculations.     

Molecular structure of aniline in the gaseous phase: A concerted study by electron diffraction and ab initio molecular orbital calculations

The molecular structure of free aniline has been investigated by gas-phase electron diffraction and ab initio MO calculations at the HF and MP2 levels of theory, using the 6-31G^*(6D) basis set. Least-squares refinement of a model withC _s symmetry, with constraints from MP2 calculations, has led to an accurate determination of the C-C-C angle at theipso position of the benzene ring, =119.0±0.2 (where the uncertainty represents total error). This parameter provides information on the extent of the interaction between the nitrogen lone pair and the system of the benzene ring, and could not be determined accurately by microwave spectroscopy. The angles at theortho, meta, andpara positions of the ring are 120.3±0.1, 120.7±0.1, and 119.0±0.3, respectively. Important bond distances are r _g(C-C)=1.398±0.003 å andr _g(C-N) =1.407±0.003 å. The effective dihedral angle between the H-N-H plane and the ring plane, averaged over the large-amplitude inversion motion of the amino group, is ¦¦=44±4. The equilibrium dihedral angle is calculated to be 41.8 at the HF level and 43.6 at the MP2 level, in agreement with far-infrared spectroscopic information. The MO calculations predict that the differencer(C_ortho-C_meta) -r(C_ipso-C_ortho) is 0.008–0.009 å. They also indicate that the nitrogen atom is displaced from the ring plane, on the side opposite to the amino hydrogens. The displacement is 0.049 å at the HF level and 0.072 å at the MP2 level. The two calculations, however, yield very different patterns for the minute deviations from planarity of the ring carbons.     

Synthesis and crystal structure of a cubane-like molybdenum copper sulphur bromide cluster [MoCu3S3Br(SCH2CH2S)(PPh3)3]·MeCN

Summary [MoCu₃S₃Br(SCH₂CH₂S)(PPh₃)₃]·MeCN, MW=1382.78, space group Pl, has the triclinic cell parametersa=12.272(11),b=13.172(7),c=20.363(3)Å, =106.26(3)^o, =95.64(5)^o, =65.79(6)^o; Z=2, V=2881.4ų. Dc=1.55 g cm^–3. MoK radiation. =0.71073Å, =22.8 cm^–1. F(000)=1348. R=0.69 for 4964 observed unique reflections [I>3(I)]. There are some distortions in the cubane-like MoCu₃S₃Br core, with three form Mo–Cu bonds. The Mo atom is bound by chelating SCH₂CH₂S and three ₃-S atoms.     

Synthesis and structure of new arylnickel(II) malonato-complexes

Summary Interaction of malonate anions with chloro(aryl)bis(organophosphine)nickel(II) complexes leads to the formation of stable (aryl)(malonato)(organophosphine)nickel(II) species, as shown by i.r. and¹H n.m.r. data. The crystal and molecular structure of (diethylmalonato-O,O)(-naphthyl)(triphenylphosphine)nickel(II), determined by x-ray methods (space group P¯1,a=10.767(9),b=16.253(16),c=9.835(13)Å, =108.97(10)⁰, =106.08(10)⁰, =89.11(7)⁰,Z= 2;R= 0.070 for 3650 independent observed reflections), shows distorted square-planar O₂PC coordination about the nickel with bond distances: Ni-P, 2.142(2)Å; Ni-O, 1.888(5) and 1.936(5)Å; Ni-C, 1.887(8)Å. The parameters and bonding of the triphenylphosphine-nickel and naphthyl moieties in the complex are normal, whereas considerable electron-delocalisation occurs in the planar ethylmalonate moiety. The -naphthyl ligand is oriented almost perpendicularly to the NiO₂CP core-malonate plane.     

[3]Ferrocenophanes with a tetramethyldisiloxane bridge: Synthesis and molecular structure

Summary 6,6,8,8-Tetramethyl-7-oxa-6,8-disila[3]ferrocenophane2 was obtained from the di(alkoxysilyl) ferrocene (H₄C₅SiMe₂OR)₂Fe (R=CH₂CH₂OCH₂CH₂OCH₂CH₂OMe) by hydrolysis and subsequent intramolecular disiloxane formation. 2,2,3,3,4,4,5,5,6,6,8,8-Dodecamethyl-7-oxa-6,8-disila-[3]ferrocenophane3 was formed by air oxidation of 2,23,3,4,4,5,5,6,6,7,7-dodecamethyl-6,7-disila[2]ferrocenophane. The crystal structures of both compounds were determined by single-crystal X-ray diffraction (2:a=8.5330(10),b=15.610(3),c=18.774(5)Å, =70.68(2), =77.94(2), =75.150(10)°,V=2259.8(8)ų,Z=6, space group P ,R=0.045,R _w =0.044;3:a=12.388(3),b=9.924(3),c=19.136(10)Å, =105.11(3)°,V=2271.2(15)ų,Z=4, space group P2₁/c,R=0.076,R _w =0.060). Owing to the flexibility of the disiloxane bridge,2 and3 are unstrained molecules.

---

[3]Ferrocenophane mit Tetramethyldisiloxan-Brücke: Synthese und Molekülstruktur

Zusammenfassung 6,6,8,8-Tetramethyl-7-oxa-6,8-disila[3]-ferrocenophan2 entsteht aus dem Di(alkoxysilyl)ferrocen (H₄C₅SiMe₂OR)₂Fe (R=CH₂CH₂OCH₂CH₂OCH₂CH₂OMe) durch Hydrolyse und anschließende intramolekulare Disiloxan-Bildung. 2,2,3,3,4,4,5,5,6,6,8,8-Dodecamethyl-7-oxa-6,8-disila[3]ferrocenophan3 wurde durch Luftoxidation von 2,2,3,3,4,4,5,5,6,6,7,7-Dodecamethyl-6,7-disila[2]ferrocenophan erhaeten. Die Kristallstrukturen beider Verbindungen wurden durch Einkristall-Röntgenstrukturanalyse bestimmt (2:a=8.5330(10),b=15.610(3),c=18.774(5)Å, =70.68(2), =77.94(2), =75.150(10)°,V=2259.8(8)ų,Z=6, Raumgruppe P ,R=0.045,R _w =0.044;3:a=12.388(3),b=9.924(3),c=19.136(10)Å, =105.11(3)°,V=2271.2(15)ų,Z=4, Raumgruppe P2₁/c,R=0.076,R _w =0.060). Wegen der Flexibilität der Disiloxan-Brücke sind2 und3 ungespannte Moleküle.

     

Viscosity B coefficients of polyethyleneglycols in water

The viscosity B coefficients of polyethylene glycols (M=62–1000) are determined at 25 °C. The B coefficient increases non-linearly with the number of ethyleneoxide (EO) units. The increase of the B coefficient per EO(0.111 dm³/mole) is less than the B value for two methylene groups (0.160 dm³/mole). This is discussed in terms of changes in the configurations of polyethylene glycols with long EO chains.Molecular size is the major factor that contributes to B at shorter chains, but solvation (hydration) becomes dominant as the number of ethyleneoxide groups increases. The hydration parameter,(gH₂O/g ethyleneglycol), shows a linear dependence on B at low mass followed by a non-linear increase at high molecular mass and the viscosity C coefficient accounts for the solute-solute interactions.Symbols absolute viscosity - _d absolute viscosity of dispersion medium - _r relative viscosity - _sp specific viscosity - ¦ _o ¦ intrinsic viscosity at infinite dilution - ¦ _c ¦ intrinsic viscosity as a function of solute concentration - partial specific volume - volume fraction - hydration (weight of H₂O hydrating 1 g of polyethylene glycol) - _c hydration as a function of solute concentration - K shape function - K _c shape function as a function of solute concentration     

Macrocyclic amidophosphoryl polyethers: Biological activity,molecular structure,and structure of the complex with calcium thiocyanate

The antihypoxic and anticonvulsant activity of eight new amidophosphoryl derivatives of crown ethers was investigated. It was found that some of them exhibit pronounced antihypoxic activity. The results of an x-ray structural and IR spectroscopic study of dibenzo-N-phenylphosphonyl-14-crown-5 (a=9.818,b=16.062,c=15.925 Å; =124.90°;V=2072 ų;M=417.2;d=1.33 g/cm³ forZ=4, 1955 independent reflections [I>3(I)] in a DAR-UM inCuK radiation,P2 ₁/b space group,R=5.2%) and dibenzo-N-adamantylphosphonyl-14-crown-5 compounds (a=11.077,b=15.936,c=16.771 Å; =56.05°;V=2456 ų;M=486.3;d=1.31 g/cm³ forZ=4, 2164 independent reflections [I>3(I)] in a DAR-UM inCuK radiation,P2₁/b space group,R=5.1%) are reported. Some details of the structure of the dibenzo-N-phenylphosphonyl-14-crown-5-complex with calcium thiocyanate and water are discussed; a polyhedron with a coordination number of six was found for the first time for calcium complexes with macrocyclic ligands. The combined examination of the results of the biological, x-ray structural, and IR spectroscopic study of macrocyclic, 14-member ligands suggested that the nature of the substituents at phosphorus affect the conformational state of the macrocycle, which remains unchanged in complexation in the investigated conditions.Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences, 142432 Chernogolovka. Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Institute of Organic Chemistry, Ukrainian Academy of Sciences, 252660 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2784–2790, December, 1992.     

Hexa(isothiocyanato)chromate(III) Hydro-Bis(Pyridine N-Oxide) Complex: Synthesis and Crystal Structure

A new complex of hexa(isothicyanato)chromate(III) hydro-bis(pyridine N-oxide) [(Py)₂H]₃[Cr(NCS)₆] was synthesized and studied by X-ray diffraction analysis. The coordination polyhedra of Cr atoms are the perfect octahedra that form the layered structure. Molecules of pyridine N-oxide form bimolecular cationic associates that compensate the charge on the complex anions. The crystals are triclinic: a = 11.559(2) Å; b = 12.644(3) Å; c = 16,110(4) Å; = 90.02(2)°; = 95.15(2)°; = 98.23(2)°; V = 2320.6(9) ų; _calcd = 1.394 g/cm³. Z = 2, space group P1¯.     

The crystal structure of Fe(SeO2OH)(SeO4)·H2O

Summary The crystal structure of the hydrothermally synthesized compound Fe(SeO₂OH) (SeO₄) · H₂O was determined by single crystal diffraction methods:a=8.355(2) Å,b=8.696(2) Å,c=9.255(2) Å, =93.72(1)°,V=670.95 ų;Z=4, space group P2₁/c,R=0.029,R _w=0.027 for 2430 independent reflections (sin /0.76 Å^–1). Isolated FeO₅(H₂O)-octahedra share five corners with [SeO₂OH] and [SeO₄] groups to form sheets parallel to (100). These sheets are interconnected via hydrogen bonds only.

---

Die Kristallstruktur von Fe(SeO₂OH)(SeO₄)·H₂O

Zusammenfassung Die Kristallstruktur der hydrothermal dargestellten Verbindung Fe(SeO₂OH) (SeO₄)·H₂O wurde mittels Einkristallbeugungsmethoden bestimmt:a=8.355(2) Å,b=8.696(2) Å,c=9.255(2) Å, =93.72(1)°,V=670.95 ų;Z=4, Raumgruppe P2₁/c,R=0.029,R _w=0.027 für 2 430 unabhängige Reflexe (sin / 0.76 Å^–1). Isolierte FeO₅(H₂O)-Oktaeder teilen fünf Ecken mit [SeO₂OH]- und [SeO₄]-Gruppen, wobei sie Schichten parallel (100) bilden. Diese Schichten sind nur über Wasserstoffbrücken miteinander verbunden.

     

The Molecular Structure and the Puckering Potential Function of Octamethylcyclotetrasilane,Si4Me8, Determined by Gas Electron Diffraction and Relaxation Constraints from Ab Initio Calculations

Gas electron diffraction data are applied to determine the geometrical parameters of the octamethylcyclotetrasilane molecule using a dynamic model in which the ring puckering is treated as a large amplitude motion. The structural parameters and parameters of the potential function were refined, taking into account the relaxation of the molecular geometry estimated from ab initio calculations at the Hartree–Fock level of theory using a 6-311G** basis set. The potential function has been described as V() = V ₀[(/ _e )² – 1]² with V ₀ = 1.0 ± 0.5 kcal/mol and _e = 28.3 ± 1.9°, where is the puckering angle of the ring. The geometric parameters at the minimum of V() (r _a in Å, in degrees and errors given as three times the standard deviations including a scale error) are as follows: r(Si—C)_av = 1.894(3), r(Si—Si) = 2.363(3), r(C—H) = 1.104(3), CSiC = 109.5(6), SiSiSi = 88.2(2), SiCH = 111.7(6), C = 4.1, where the tilt C was estimated from ab initio constraints. The structural parameters are compared with those obtained for related compounds.     

X-Ray Diffraction Analysis of Aluminum Hexamolybdenocobaltate(III) and Hexamolybdenocromate(III)

Isostructural crystals of aluminum hexamolybdenocobaltate(III) and hexamolybdenocromate(III) Al[MMo₆O₁₈(OH)₆] · 16H₂O (M = Co(III) and Cr(III)) were studied using X-ray diffraction analysis. These compounds crystallize in the triclinic system: space group P , Z = 1, (calcd) = 2.665 and 2.611 g/cm³, respectively. The unit cell parameters were determined: for aluminum hexamolybdenocobaltate(III), a = 6.796(1) Å, b= 11.248(2) Å, c = 11.568(2) Å; = 101.36(2)°, = 96.95(2)°, = 102.23(2)°; for aluminum hexamolybdenocromate(III), a = 6.838(1) Å, b = 11.312(2) Å, c = 11.605(2) Å; = 101.29(3)°, = 97.13(3)°, = 102.15(3)°.     

Nuclear magnetic resonance study of the ligand interchange of Ba2+-18-crown-6 complex in methanol solution

Exchange kinetics of Ba²⁺-18-crown-6 complex in deuterated methanol solution was studied by proton NMR line-shape analysis of a series of solutions containing equal population of free and complexed 18-crown-6, but varying concentration of the macrocycle, at various temperatures. From –33 to 37°C, the predominant mechanism for the exchange of the ligand between the two sites is a bimolecular pathway which is characterized by the following activation parameters:E _a=47±2 kJ-mol^–1; H =45±2 kJ-mol^–1; S =–8±4 J-mol^–1-K^–1. However, the contribution of a dissociative mechanism with activation parametersE _a=36±5 kJ-mol^–1, H =33±5 kJ-mol^–1 and S =104±18 J-mol^–1-K^–1 becomes more important at higher temperatures.     

The synthesis and crystal structure of a cubane-like tungsten copper sulphur cluster, [W4CuS4 2P(OEt)2 3(I)(μ2-PhCO2)(MeCN)]

Summary The title compound [W₃C₃S₄{S₂P(OEt)₂}₃(I)(₂ ^–PhCO₂)(MeCN)] crystallized in triclinic system with space group P1 and cell dimensiona=11.645(6),b=18.565(2),c=11.292(7)Å, =96.15(3)°, =113.65(3)°, =93.77(3)°, V=2207.6ų, Z=2, Mr=1588.09, D_c=2.39 g cm^–3. MoK radiation, =0.71073 Å, =97.3 cm^–1, F(000)=1488, R=0.042 for 5588 observed unique reflections I3(I). There are some distortions in the cubane-like W₃CuS₄ core, with three W-W bonds and three weak W-Cu bonds. Two W atoms are coordinated by PhCO₂ bridge ligand, the other W atom is coordinated to the N atom of MeCN.     

On the reliability of equilibrium data of the charge-transfer complex between 2,3-dichloro-1,4-naphthoquinone and hexamethylbenzene

In view ofHammond's warning⁶ about the Conspiracy of errors, found in the case of low values of equilibrium constants of charge-transfer complexes a case is made out for redetermining the values for the system hexamethylbenzene—2,3-dichloro-1,4-naphthoquinone. Uncertainties in the parameters were estimated using theLiptay ⁸ matrix procedure. The solvent used was dichloromethane. The following data were obtained at 25°C: vC T = 22,220 cm^–1;E _A=0.99 eV;K =2599±57 l²·cm^–1·mol^–2. _max= 1020 ± 148 cm^–1··1;K=2.55±0.37 l·mol^–1; –H=2.7±0.3 kcal·mol^–1.With 1 Figure     

On the crystal chemistry of three copper(II)-arsenates: Cu3(AsO4)2-III,Na4Cu(AsO4)2, and KCu4(AsO4)3

The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu₃(AsO₄)₂-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å^–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)^[4+1] atom in Cu₃(AsO₄)₂-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu₄(AsO₄)₃ the Cu(1)^[4]O₄ square and the As(1)O₄ tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO₄ square and the AsO₄ tetrahedron. The two Na atoms in Na₄Cu(AsO₄)₂ are [6] coordinated, the K atom in KCu₄(AsO₄)₃ is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu₃(AsO₄)₂-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å^–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)^{[4 + 1]}-Atom in Cu₃(AsO₄)₂-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu₄(AsO₄)₃ haben das Cu(1)^[4]O₄-Quadrat und das As(1)O₄-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO₄-Quadrat und AsO₄-Tetraeder bedingt. Die zwei Na-Atome in Na₄Cu(AsO₄)₃ sind durch O-Atome [6]-koordiniert, das K-Atom in KCu₄(AsO₄)₃ ist [8]-koordiniert.

---

Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu₃(AsO₄)₂-III, Na₄Cu(AsO₄)₂ und KCu₄(AsO₄)₃

     

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

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

Verfeinerung der Kristallstruktur von Kupfer(II)-hydroxichlorid,Cu(OH)Cl

The crystal structure of Cu(OH)Cl [a=5.555 (2) Å,b=6.671 (4) Å,c=6.127 (2) Å, =114.88 (3)°, space group P2_I/a,Z=4] was refined for 810 observed reflections with sin /0.80 Å^–1 toR=0.035. Crystals were synthesized under hydrothermal conditions. The copper atom is planar four coordinated by three oxygen atoms and one chlorine atom; two further chlorine atoms complete its coordination. The copper polyhedra share edges to build up sheets, which are connected by hydrogen bonds to the chlorine atoms of adjacent sheets.

     

Coordination chemistry of alkali and alkaline earth cations: Synthesis and crystal structure of potassium(benzo-15-crown-5)2 [3,5-dinitrobenzoate(3,5-dinitrobenzoic acid)2]

The interaction of K(35-Dnb) (35-Dnb=3,5-dinitrobenzoate) with benzo-15-crown-5 (B15C5) in ethanol yields a charge-separated sandwich structured complex [K(B15C5)₂]⁺[35-Dnb(35-DnbH)₂]^– even when equimolar amounts of reactants were used and no external 35-DnbH was added to the reaction mixture. The complex (KC₄₉H₅₁O₂₈N₆, FW=1211.1), is monoclinic,P2₁/c,a=11.063(2),b=10.680(1),c=46.548(8) Å, =91.629(2)⁰,Z=4,D ₀=1.485 g/cm³,D _c=1.468 g/cm³, CuK =1.5418 Å, =17.01 cm^–1, 2<130⁰,F(000)=2520,T=298 K. FinalR for the 6618 observed reflections was 0.071. In the sandwich moiety, the K⁺ is 10-coordinated through all the oxygens of the crown molecules (K⁺–O, 2.76–3.11 Å). The 35-Dnb anion lies 5.3 Å below the lower crown mean plane and is charge separated with respect to K⁺ (K⁺–O^–>7 Å) but undergoes strong hydrogen bonding (2.59 and 2.49 Å) through each carboxylate oxygen with the carboxylic protons of two separate 35-DnbH molecules. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82014 (52 pages).