Synthesis and properties of ms- and β-substituted Pt(II) and Pt(IV) tetraphenylporphyrinates

The interaction of 5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetra-(4-chlorophenyl)porphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with platinum(II) chloride in boiling phenol has been studied. The corresponding platinum(II) porphyrinates have been synthesized; their subsequent treatment with bromine in chloroform resulted in platinum(IV) porphyrinates. The Pt(II) and Pt(IV)(Br)₂ porphyrinates have been identified by elemental analysis, electron absorption, IR, and ¹H NMR spectroscopy.     

Studies of surface processes of electrocatalytic reduction of CO_2 on Pt(210), Pt(310) and Pt(510)

Surface processes of CO2 reduction on Pt(210), Pt(310), and Pt(510) electrodes were studied by cyclic voltammetry. Different surface structures of these platinum single crystal electrodes were obtained by various treatment conditions. The experimental results illustrated that the electrocatalytic activity of Pt single crystal electrodes towards CO2 reduction is decreased in an order of Pt(210)>Pt(310)>Pt(510), i.e., with the decrease of (110) step density on well-defined surfaces. When the surfaces were reconstructed due to oxygen adsorption, the catalytic activity of all the three electrodes has been enhanced to a cer- tain extent. Although the activity order remains unchanged, the electrocatalytic activity has been en- hanced more significantly as the density of (110) step sites is more intensive on the Pt single crystal surface. It has revealed that the more open the surface structure is, the more active the Pt single crystal electrode will be, and the easier for the electrode to be transformed into a surface structure that exhib- its higher activity under external inductions. However, the relatively ordered surfaces of Pt single crystal electrode are comparatively stable under the same external inductions. The present study has gained knowledge on the interaction between CO2 and Pt single crystal electrode surfaces at a micro- scopic level, and thrown new insight into understanding the surface processes of electrocatalytic re- duction of CO2.     

High-pressure synthesis and local structure of corundum-type In(2-2x)Zn(x)Sn(x)O(3) (x ≤ 0.7)

The corundum-type In(2-2x)Zn(x)Sn(x)O(3) solid solution (cor-ZITO, x ≤ 0.7) was synthesized at 1000 °C under a high pressure of 70 kbar. cor-ZITO is a high-pressure polymorph of the transparent conducting oxide bixbyite-In(2-2x)Zn(x)Sn(x)O(3) (x ≤ 0.4). Analysis of the extended X-ray absorption fine structure suggests that significant face-sharing of Zn and Sn octahedra occurs, as expected for the corundum structure type. In contrast to the ideal corundum structure, however, Zn and Sn are displaced and form oxygen bonds with lengths that are similar to those observed in high-pressure ZnSnO(3). Powder X-ray diffraction patterns of cor-ZITO showed the expected unit cell contraction with increased cosubstitution, but no evidence for ilmenite-type ordering of the substituted Zn and Sn. A qualitative second harmonic generation measurement, for the solid solution x = 0.6 and using 1064 nm radiation, showed that Zn and Sn adopt a polar LiNbO(3)-type arrangement.     

Synthesis and molecular structure of (NBu4)x[Pt(C6Cl5)2(μ-Cl)2Aglx: A novel chain polymeric compound

The reaction of the NBu⁺₄ salt of trans-[PtCl₂(C₆Cl₅)₂]²⁻ with AgNo in acetone-methanol affords polymeric [Pt(C₆Cl₅)₂(μ-Cl)₂Ag]^x−_x, as the NBu⁺₄ salt. The chain anion consists of planar Pt(C₆Cl₅)₂Cl₂ units linked by Ag atoms, in which there are AgCl bonds of two types: those which result in Pt(μ-Cl)Ag links and those in which ortho-Cl atoms of C₆Cl₅ units make close approaches (3.01 and 3.09 Å) to Ag atoms.     

F+ and F⁻ affinities of simple N(x)F(y) and O(x)F(y) compounds

Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for the neutral and ionic N(x)F(y) and O(x)F(y) systems using coupled cluster theory with single and double excitations and including a perturbative triples correction (CCSD(T)) method with correlation consistent basis sets extrapolated to the complete basis set (CBS) limit. To achieve near chemical accuracy (±1 kcal/mol), three corrections to the electronic energy were added to the frozen core CCSD(T)/CBS binding energies: corrections for core-valence, scalar relativistic, and first order atomic spin-orbit effects. Vibrational zero point energies were computed at the CCSD(T) level of theory where possible. The calculated heats of formation are in good agreement with the available experimental values, except for FOOF because of the neglect of higher order correlation corrections. The F(+) affinity in the N(x)F(y) series increases from N(2) to N(2)F(4) by 63 kcal/mol, while that in the O(2)F(y) series decreases by 18 kcal/mol from O(2) to O(2)F(2). Neither N(2) nor N(2)F(4) is predicted to bind F(-), and N(2)F(2) is a very weak Lewis acid with an F(-) affinity of about 10 kcal/mol for either the cis or trans isomer. The low F(-) affinities of the nitrogen fluorides explain why, in spite of the fact that many stable nitrogen fluoride cations are known, no nitrogen fluoride anions have been isolated so far. For example, the F(-) affinity of NF is predicted to be only 12.5 kcal/mol which explains the numerous experimental failures to prepare NF(2)(-) salts from the well-known strong acid HNF(2). The F(-) affinity of O(2) is predicted to have a small positive value and increases for O(2)F(2) by 23 kcal/mol, indicating that the O(2)F(3)(-) anion might be marginally stable at subambient temperatures. The calculated adiabatic ionization potentials and electron affinities are in good agreement with experiment considering that many of the experimental values are for vertical processes.     

Synthesis and Structural Characterization of Na(x)Si(136) (0 < x ≤ 24) Single Crystals and Low-Temperature Transport of Polycrystalline Specimens

Na(x)Si(136) clathrate-II single crystals with x = 2.9, 5.1, 8.2, and 14.7 were prepared by a two-step process. In the first step, Na(24)Si(136) single crystals were grown from the precursor Na(4)Si(4) by reaction of the vapor phase with spatially separated graphite in a closed volume. In the second step, the Na(24)Si(136) single crystals were subjected to thermal decomposition in a nitrogen atmosphere at 10 Torr and 405 °C. The Na content was controlled by the duration of thermal decomposition. The structural properties were investigated using single-crystal X-ray diffraction and compared with those of single-crystal Na(24)Si(136). The quality of the obtained products also allowed for low-temperature transport property measurements on agglomerates of crystals allowing for an investigation into the low-temperature electrical and thermal properties as a function of Na content.     

Synthesis and characterization of sodium vanadium oxide gels: the effects of water (n) and sodium (x) content on the electrochemistry of Na(x)V2O5·nH2O

Sodium vanadium oxide gels, Na(x)V(2)O(5)·nH(2)O, of varying sodium content (0.12 < x < 0.32) were prepared by careful control of an ion exchange process. The water content (0.23 > n > 0.01) and interlayer spacing were found to be inversely proportional to the sodium level (x), thus control of sodium (x) content provided a direct, chimie douce approach for control of hydration level (n) and interlayer spacing, without the need for high temperature treatment to affect dehydration. Notably, the use of high temperatures to modify hydration levels can result in crystallization and collapse of the interlayer structure, highlighting the distinct advantage of our novel chimie douce synthesis strategy. Subsequent to synthesis and characterization, results from an electrochemical study of a series of Na(x)V(2)O(5)·nH(2)O samples highlight the significant impact of interlayer water on delivered capacity of the layered materials. Specifically, the sodium vanadium oxide gels with higher sodium content and lower water content provided higher capacities in lithium based cells, where capacity delivered to 2.0 V under C/20 discharge ranged from 170 mAh/g for Na(0.12)V(2)O(5)·0.23H(2)O to 300 mAh/g for Na(0.32)V(2)O(5)·0.01H(2)O. The capacity differences were maintained as the cells were cycled.     

Synthesis and Ionic Conductivity of LiZr2(VO4)x(PO4)3 – x

Russian Journal of Electrochemistry - Vanadate phosphates LiZr2(VO4)x(PO4)3 – x are synthesized by the sol-gel technique with subsequent annealing and studied using X-ray diffraction...     

Chemical pressure and rare-earth orbital contributions in mixed rare-earth silicides La(5-x)Y(x)Si4 (0 ≤ x ≤ 5)

A crystallographic study and theoretical analysis of the structural and La/Y site preferences in the La(5-x)Y(x)Si(4) (0 ≤ x ≤ 5) series prepared by high-temperature methods is presented. At room temperature, La-rich La(5-x)Y(x)Si(4) phases with x ≤ 3.0 exhibit the tetragonal Zr(5)Si(4)-type structure (space group P4(1)2(1)2, Z = 4, Pearson symbol tP36), which contains only Si-Si dimers. On the other hand, Y-rich phases with x = 4.0 and 4.5 adopt the orthorhombic Gd(5)Si(4)-type structure (space group Pnma, Z = 4, Pearson symbol oP36), also with Si-Si dimers, whereas Y(5)Si(4) forms the monoclinic Gd(5)Si(2)Ge(2) structure (space group P2(1)/c, Z = 4, Pearson symbol mP36), which exhibits 50% "broken" Si-Si dimers. Local and long-range structural relationships among the tetragonal, orthorhombic, and monoclinic structures are discussed. Refinements from single crystal X-ray diffraction studies of the three independent sites for La or Y atoms in the asymmetric unit reveal partial mixing of these elements, with clearly different preferences for these two elements. First-principles electronic structure calculations, used to investigate the La/Y site preferences and structural trends in the La(5-x)Y(x)Si(4) series, indicate that long- and short-range structural features are controlled largely by atomic sizes. La 5d and Y 4d orbitals, however, generate distinct, yet subtle effects on the electronic density of states curves, and influence characteristics of Si-Si bonding in these phases.     

Crystal structure of Ag2TeS3 and Na(Na1−x Ag x )TeS3 (x≈0.5) and the geometry of Te(IV)S3 polyhedra

Summary Structural data determined by single crystal X-ray experiments (T=300 K) are reported for Ag₂TeS₃ (monoclinic, Cc-C _s ⁴ ;a=6.783(1),b=11.567(2),c=7.693(1) Å; =114.44(1)°;Z=4;R=0.044) and for Na(Na_1–x Ag _x )TeS₃ x0.5; monoclinic, P2₁/c-C _2h ⁵ ;a=5.761(9),b=12.171(8),c=8.342(4) Å; =92.26(6)°;Z=4;R=0.030). In both compounds the atomic arrangements are characterized by isolated trigonal pyramidal TeS₃ polyhedra, irregularly coordinated Ag and Na atoms forming AgS₄ and (Na, Ag)S₄ polyhedra, and slightly distorted NaS₆ octahedra. Crystals of both compounds were synthesized under moderate hydrothermal conditions from an equimolar mixture of the elements in concentrated aqueous ammonia and 5N NaOH solution, respectively.

---

Kristallstruktur von Ag₂TeS₃ und Na(Na_1–x Ag _x )TeS₃ (x0.5) nebst einem Vergleich der Geometrie von TeS₃-Gruppen

Zusammenfassung Es wird über die mittels Röntgenbeugungsexperimenten an Einkristallen bei 300 K bestimmten Strukturen von Ag₂TeS₃ (monoklin Cc-C _s ⁴ ;a=6.783(1),b=11.567(2),c=7.693(1) Å; =114.44(1)°;Z=4;R=0.044) und Na(Na_1–x Ag _x )TeS₃ (x0.5; monoklin, P2₁/c-C _2h ⁵ ;a=5.761(9),b=12.171(8),c=8.342(4)Å; =92.26(6)°;Z=4;R=0.030) berichtet. In beiden Verbindungen ist die Atomanordnung durch isolierte trigonal-pyramidale TeS₃-Polyeder, unregelmäßig koordinierte Ag- und Na-Atome, AgS₄- und (Na, Ag)S₄-Polyeder bildend, sowie leicht verzerrte NaS₆-Oktaeder charakterisiert. Kristalle der beiden Verbindungen wurden unter moderaten Hydrothermalbedingungen aus einem equimolaren Gemenge der Elemente und konzentrierter wäßriger Ammoniaklösung bzw. 5N NaOH-Lösung gezüchtet.

     

Preparation, Characterization of Solid SolutionLa_4BaCu_(5- x)Mn_xO_(13 λ)(x= 0—5) and ItsCatalytic Activity in the Reduction of NO by CO

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｉｓｃｏｖｅｒｙｏｆｔｈｅｓｕｐｅｒｃｏｎｄｕｃｔｉｖｉｔｙｏｆｔｈｅＢａ－Ｌａ－Ｃｕ－Ｏｓｙｓｔｅｍａｔｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｈａｓｇｒｅａｔｌｙｓｔｉｍｕｌａｔｅｄｔｈｅｉｎｖｅｓｔｉｇａｔｉｏｎｏｆｃｕｐｒａｔｅｓ［１］．Ｃｕｐｒａｔｅｓｈａｖｅｂｅｅｎｆｏｕｎｄｔｏｂｅａｃｔｉｖｅｃａｔａｌｙｓｔｓｆｏｒｓｅｖｅｒａｌｒｅａｃｔｉｏｎｓ，ｉｎｃｌｕｄｉｎｇｔｈｅｒｅｄｕｃｔｉｏｎａｎｄｄｅｃｏｍｐｏｓｉｔｉｏｎｏｆＮ２Ｏ，ＮＯａｎｄＮＯ２，ｔｈｅ…     

Determination of the stability constants of Pb–(DIPSO)x–(OH)y and Pb–(AMPSO)x–(OH)y systems

In this work, complexation between lead ion and the ligands 3-[N,N-bis(2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) and N-(1,1-dimethyl-2-hydroxyethyl)-3-amino-2-hydroxypropanesulfonic acid (AMPSO), which are commercial pH buffers, is presented. Both ligands form complexes with lead in their pH buffer range (between pH 6.5 and 8.5 for DIPSO and between pH 8.0 and 9.0 for AMPSO). The final models and the overall stability constants, which are reported here, were determined by direct current polarography and glass electrode potentiometry [only for the Pb–(DIPSO)_x–(OH)_y system] at 25.0 °C and 0.1 M KNO₃ ionic strength. For the Pb–(DIPSO)_x–(OH)_y system, the proposed final model contains PbL, PbL₂, PbL₂(OH), and PbL₂(OH)₂ with stability constants, as log β, of 3.4 ± 0.1, 6.35 ± 0.15, 12.8 ± 0.2, and 18.0 ± 0.3, respectively. For the Pb–(AMPSO)_x–(OH)_y system, the species observed are PbL, PbL(OH), and PbL(OH)₂ with stability constants, as log β, of 2.9 ± 0.5, 9.4 ± 0.1, and 14.5 ± 0.2, respectively. For AMPSO, the possible adsorption of the ligand at the mercury electrode surface was evaluated by alternating current polarography through calculation of the capacitance of the double layer.     

Cluster synthesis 37—Platinum-ruthenium carbido-cluster complexes: The syntheses and structural characterizations of PtRu5(C)(CO)16, Pt2Ru5(C)(CO)13(COD)2, and Pt3Ru5(C)(CO)14(COD)2

From the reaction of [Ru₅(C)(CO)₁₄]^2– with Pt(COD)Cl₂, COD=1, 5 cyclooctadiene, the new platinum-ruthenium carbido cluster complex PtRu₅ (C)(CO)₁₄(COD),1, was obtained in 41% yield. When1 was allowed to react with carbon monoxide (25°C/1 atm), the new complex PtRu₅(C)(CO)₁₆,2, was obtained almost quantitatively (97% yield). Compound2 was characterized by IR and single-crystal X-ray diffraction analysis. The six metal atoms are arranged in the form of an octahedron with the carbide ligand located in the center. Compound1 is believed to have a similar structure to2 except for a COD ligand coordinated to the platinum atom. When activated by treatment with Me₃NO, compound2 reacts with Pt(COD)₂ at 25°C to yield two higher nuclearity cluster complexes, Pt₂Ru₅C(CO)₁₃(COD)₂.3, and Pt₃Ru₅C(CO)₁₄(COD)₂,4. The structure of3 is similar to that of1, but contains a Pt(COD) grouping capping one Ru₃ triangle of the PtRu₅ octahedron. The structure of4 consists of a PtRu₅ octahedron with two Pt(COD) capping groups, one on an Ru₃ triangle and the other on a PtRu₂ triangle of the octahedron. Crystal data: for2, space group=P2₁/n,a=9.341 (2) Å,b=14.957 (3) Å,c=36.80 (1) Å, =90.38 (2) °,Z=8, 4034 reflections,R=0.030, for3, space group=P2₁/c,a=14.998 (3) Å,b=10.288 (3) Å,c=26.581 (7) Å, =102.75 (2) °,Z=4, 2917 reflections,R=0.028. for4, space group=P2₁/n,a=13.412 (4) Å,b=16.252 (4) Å,c=20.107 (4) Å, =106.13 (2) °,Z=4, 2745 reflections,R=0.032.     

Structural and electrical properties of sol–gel grown (1 − x) (ZnO) + (x) (SnO2) (x = 0, 0.25, 0.5) nanocomposites

Journal of Sol-Gel Science and Technology - Semiconducting oxide nanocomposites of ZnO/SnO2 with different weight ratio, i.e. (i) ZnO:SnO2?=?100:0 (ZnO0), (ii)...     

Synthesis and crystal structure of Mo6−x Nb x I11 (x = 1–1.5)

A solid solution Mo_{6 ? x} Nb _x I₁₁ (x = 1.1–1.5) containing cluster cores {Mo₅NbI₈} is obtained by the high-temperature reaction of molybdenum, niobium, and iodine (550°C, 70 h, quartz ampule). According to the X-ray diffraction data, heating at 800°C in a molybdenum container results in the decomposition of the solution to Mo₆I₁₂ and Nb₆I₁₁. According to the X-ray structure analysis data, the compounds are isostructural to the high-spin modification Nb₆I₁₁ (space group Pccn). The presence of Nb atoms in the structure changes the structural type from the layered (Mo₆I₁₂) to framework structure, noticeably increases the metalmetal distances (2.661–2.716 Å, 2.695 Å) Mo₆ octahedron with the retention of the distance from the metal (M) to the μ₃-“capped” I atoms, and strongly elongates the M₆-I-M₆ bridges almost to the value observed in Nb₆I₁₁.     

Structures of Pd(CN)2 and Pt(CN)2: intrinsically nanocrystalline materials?

Analysis and modeling of X-ray and neutron Bragg and total diffraction data show that the compounds referred to in the literature as "Pd(CN)(2)" and "Pt(CN)(2)" are nanocrystalline materials containing small sheets of vertex-sharing square-planar M(CN)(4) units, layered in a disordered manner with an intersheet separation of ~3.44 ? at 300 K. The small size of the crystallites means that the sheets' edges form a significant fraction of each material. The Pd(CN)(2) nanocrystallites studied using total neutron diffraction are terminated by water and the Pt(CN)(2) nanocrystallites by ammonia, in place of half of the terminal cyanide groups, thus maintaining charge neutrality. The neutron samples contain sheets of approximate dimensions 30 ? × 30 ?. For sheets of the size we describe, our structural models predict compositions of Pd(CN)(2)·xH(2)O and Pt(CN)(2)·yNH(3) (x ≈ y ≈ 0.29). These values are in good agreement with those obtained from total neutron diffraction and thermal analysis, and are also supported by infrared and Raman spectroscopy measurements. It is also possible to prepare related compounds Pd(CN)(2)·pNH(3) and Pt(CN)(2)·qH(2)O, in which the terminating groups are exchanged. Additional samples showing sheet sizes in the range ~10 ? × 10 ? (y ~ 0.67) to ~80 ? × 80 ? (p = q ~ 0.12), as determined by X-ray diffraction, have been prepared. The related mixed-metal phase, Pd(1/2)Pt(1/2)(CN)(2)·qH(2)O (q ~ 0.50), is also nanocrystalline (sheet size ~15 ? × 15 ?). In all cases, the interiors of the sheets are isostructural with those found in Ni(CN)(2). Removal of the final traces of water or ammonia by heating results in decomposition of the compounds to Pd and Pt metal, or in the case of the mixed-metal cyanide, the alloy, Pd(1/2)Pt(1/2), making it impossible to prepare the simple cyanides, Pd(CN)(2), Pt(CN)(2), or Pd(1/2)Pt(1/2)(CN)(2), by this method.     

Insertion reactions of [Pt(PPh3)2] fragments into the four-membered ring complex [W(CO)5PPhC(OEt)CPhCHPh]. Crystal and molecular structures of [Pt(dppe)PPh(W(CO)5)C(OEt)CPhCHPh] and [Pt(PPh3)2((W(CO)5)PhPC(OEt)CPhCHPh)(η2-PC))]

Insertion of platinum bis(phosphane) fragments into a 1,2-dihydrophosphete ring lead to complexes derived from a 1-phosphabuta-1,3-diene species.     

Phase Evolution and Magnetic Properties of Sn_(1-2x)Fe_xNb_xO_2(0.45≤x≤0.50)

Sn1-2xFexNbxO2(0.45≤x≤0.50) samples were prepared at 1000 ℃ via a simple chemical co-precipitation method.The effects of the concentrations of Sn doped on the structures and magnetic properties of the samples have been investigated.A systematic variation from monoclinic to orthorhombic FeNbO4 structure was observed with increasing Sn content.The phase evolutions were observed from monoclinic structure with x=0.50 to the coexistence of monoclinic and orthorhombic structures with x=0.48,0.47,0.46,and then to orthorhombic structure with x=0.45.Antiferromagnetic behavior was observed for all the samples,and the magnetic ordering temperatures decrease with increasing Sn concentration,which further indicated the sequence of phase transitions.The results suggest that the incorporation of Sn can stabilize the orthorhombic FeNbO4.