Crystal structure of the new compound Co6(TeO3)2(TeO6)Cl2

The new compound Co₆(TeO₃)₂(TeO₆)Cl₂ has been isolated during an investigation of the system CoO:CoCl₂:TeO₂. The new compound is deep purple in color and crystallizes in the tetragonal system, space group P4₂/mbc, a=8.3871(7) Å, c=18.5634(19) Å, Z=4. The Co(II) ions have octahedral [Co1O₆] and tetrahedral [Co2O₃Cl] coordinations. Tellurium is present both as Te(IV) with a tetrahedral [Te1O₃E] coordination, where E is the 5s² lone-pair and as Te(VI) with an octahedral [Te2O₆] coordination. The structure is made up of intersecting layers of tetrahedra forming channels comprising octahedra chains that run along the c-axis. The new compound is the first cobalt tellurium oxochloride described.     

Crystal structure and magnetic properties of two new antiferromagnetic spin dimer compounds; FeTe3O7X (X = Cl, Br)

Two new isostructural layered oxohalides FeTe(3)O(7)X (X = Cl, Br) were synthesized by chemical vapor transport reactions, and their crystal structures and magnetic properties were characterized by single-crystal X-ray diffraction, Raman spectroscopy, magnetic susceptibility and magnetization measurements, and also by density functional theory (DFT) calculations of the electronic structure and the spin exchange parameters. FeTe(3)O(7)X crystallizes in the monoclinic space group P2(1)/c with the unit cell parameters a = 10.7938(5), b = 7.3586(4), c = 10.8714(6) ?, β = 111.041(5)°, Z = 4 for FeTe(3)O(7)Cl, and a = 11.0339(10), b = 7.3643(10), c = 10.8892(10) ?, β = 109.598(10)°, Z = 4 for FeTe(3)O(7)Br. Each compound has one unique Fe(3+) ion coordinating a distorted [FeO(5)] trigonal bipyramid. Two such groups share edges to form [Fe(2)O(8)] dimers that are isolated from each other by Te(4+) ions. The high-temperature magnetic properties of the compounds as well as spectroscopic investigations are consistent with an isolated antiferromagnetic spin dimer model with almost similar spin gaps of ~35 K for X = Cl and Br, respectively. However, deviations at low temperatures in the magnetic susceptibility and the magnetization data indicate that the dimers couple via an interdimer coupling. This interpretation is also supported by DFT calculations which indicate an interdimer exchange which amounts to 25% and 10% of the intradimer exchange for X = Cl and Br, respectively. The magnetic properties support the counterion character and a weak integration of halide ions into the covalent network similar to that in many other oxohalides.     

Lattice potential energies and thermochemical properties of triethylammonium halides (Et3NHX) (X = Cl,Br, and I)

A series of triethylammonium halides (Et₃NHCl, Et₃NHBr, and Et₃NHI) was synthesized. The crystal structures of the three compounds were characterized by X-ray crystallography. The lattice potential energies and ionic radius of the common cation of the three compounds were obtained from crystallographic data. Molar enthalpies of dissolution of the compounds at various values of molality were measured in the double-distilled water at T = 298.150 K by means of an isoperibol solution-reaction calorimeter. According to Pitzer’s theory, the values of molar enthalpies of dissolution at infinite dilution and Pitzer’s parameters of the compounds were obtained. The values of apparent relative molar enthalpies, relative partial molar enthalpies of the solvent and the compounds at different molalities were derived from the experimental values of molar enthalpies of dissolution of the compounds. Finally, hydration enthalpy of the common cation Et₃NH⁺ was calculated to be ΔH₊ = ?(150.386 ± 4.071) kJ · mol^?1 by designing a thermochemical cycle.     

Coupling of terminal alkynes by RuHXL2 (X = Cl or N(SiMe3)2, L = PiPr3)

The compounds RuL₂HX, where L = PⁱPr₃ and X = Cl or N(SiMe₃)₂, are catalyst precursors for dimerization of terminal alkynes to enynes and also to cumulenes at 23 °C; selectivity among these products is X-dependent, but not high. Conversion of Ru species onto the catalytic cycle was undetectably small, so alternative approaches to understanding the catalytic mechanism were employed: stoichiometric reactions, independent synthesis of candidate intermediates, and trapping with CO. These show the intermediacy of vinylidenes and vinyl compounds, and reveal conversion of cumulenes to the thermodynamically more stable enynes.     

Insight into the mechanism of diazocompounds transformation catalyzed by hetero cuboidal clusters [Mo3CuQ4(MeBPE)3X4]+, (Q = S,Se; X = Cl,Br): The catalytically active species

Two enantiomerically pure trinuclear compounds of formula (P)-[Mo₃S₄{(R,R)-Me–BPE}₃Br₃]Br and (P)-[Mo₃Se₄{(R,R)-Me–BPE}₃Cl₃]Cl, (P)-1b.Br and (P)-1c.Cl, respectively, have been synthesized in a good yield and a stereospecific manner by excision of polymeric [Mo₃Q₇X₄]_n (Q = S or Se, X = Cl or Br) phases with (R,R)-Me–BPE{1,2-bis[(2R,5R)-2,5-(dimethylphospholan-1-yl)]ethane}. They have been transformed into chiral hetereo cuboidal compounds [Mo₃S₄{(R,R)-Me–BPE}₃Br₃]PF₆, (P)-2b.PF₆, and [Mo₃Se₄{(R,R)-Me–BPE}₃Cl₃]PF₆, (P)-2c.PF₆, by reaction with copper salts. All these compounds have been characterized by ³¹P NMR, IR, UV–Vis, mass spectrometry, elemental analysis, and chiral dichroism. The catalytic potential of tetranuclear cuboidal compounds has been assessed in the paradigm intermolecular cyclopropanation reaction of styrene with ethyl diazoacetate. Results are compared with those obtained for the analogue [Mo₃S₄{(R,R)-Me–BPE}₃Cl₃]PF₆, (P)-2a.PF₆. The catalytic data demonstrate that the Se derivative (P)-2c.PF₆ is less reactive than the S analogues, but it leads to a similar product distribution as the sulfide analogue (P)-2a.PF₆. By contrast, exchange of chlorine by the bulky bromine gives rise to a catalyst which makes the carbene dimerization more competitive. These data agree with temporal breaking of one of the Cu–Q bonds to generate an active catalytic species.     

Isomerism in tetrahedral rhenium cluster complexes [Re4Q4(PMe2Ph)4X8]·nCH2Cl2 (Q = Se, X = Br; Q = Te, X = Cl, Br)

Three new tetrahedral rhenium cluster compounds [Re₄Se₄(PMe₂Ph)₄Br₈]·1.5CH₂Cl₂ (1), [Re₄Te₄(PMe₂Ph)₄Br₈]·CH₂Cl₂ (2), and [Re₄Te₄(PMe₂Ph)₄Cl₈]·CH₂Cl₂ (3) have been synthesized by the reaction of the corresponding precursor chalcohalide complexes [Re₄Q₄(TeX₂)₄X₈] (X = Br, Q = Se (for 1), Te (for 2); X = Cl, Q = Te (for 3)) with dimethylphenylphosphine in CH₂Cl₂. All compounds have been characterized by X-ray single-crystal diffraction and elemental analyses, IR and ³¹P NMR spectroscopy. ³¹P NMR spectroscopy indicates the formation of isomers in solution, confirmed by single-crystal X-ray analysis.     

Structural,electronic and magnetic properties of cementite-type Fe3X (X = B,C, N) by first-principles calculations

Using first-principles technique, the crystal structure of cementite-type Fe₃N is predicted. The average magnetic moment (Ms) of cementite-type Fe₃N is also predicted as 1.4929 μ_B/atom. The Ms of Fe₃N is bigger than that of Fe₃C, but smaller than that of Fe₃B. Fe Ms between two different Fe sites in Fe₃N are different (2.0541 and 2.0139 μ_B), which indicates that Fe Ms are sensitive to the local short-range order in the cementite-type crystal. The Ms of B, C and N are ?0.3525, ?0.2474 and ?0.1102 μ_B/atom in Fe₃X (X = B, C, N), respectively. The chemical bonds of Fe₃X (X = B, C, N) take on metallicity, covalence, and ionicity. The ionicity of Fe₃X (X = B, C, N) strengthens and the covalence of Fe–X weakens, going from Fe₃B, Fe₃C to Fe₃N.     

Electronic structure and molecular properties of the [Mo6X8L6]; X = Cl, Br, I; L = F, Cl, Br, I clusters

Relativistic TDDFT calculations including spin orbit interactions via the ZORA approximation and solvent effects were carried out on the [Mo₆X₈L₆]²⁻ X = Cl, Br, I ; L = F, Cl, Br, I clusters. These calculations indicate that the closely spaced lowest excited states are largely centered on the cubic [Mo₆X₈]⁴⁺ core. Thus, our calculations and the electronic similarities with the strongly luminescent [Mo₆Cl₈Cl₆]²⁻, [Mo₆Br₈Br₆]²⁻ and [Mo₆I₈I₆]²⁻ clusters, suggest that the clusters [Mo₆Cl₈F₆]²⁻, [Mo₆Br₈F₆]²⁻, [Mo₆I₈F₆]²⁻, [Mo₆I₈Cl₆]²⁻ and [Mo₆I₈Br₆]²⁻ studied here might be also luminescent. The calculated bond energies and reactivity indexes indicate that the most labile clusters are those with axial iodide ligands.     

Crystal structure and magnetic properties of FeTe2O5X (X=Cl, Br): a frustrated spin cluster compound with a new Te(IV) coordination polyhedron

A new layered transition metal oxohalide, FeTe2O5ClxBr1-x, has been identified. It crystallizes in the monoclinic space group P21/c. The unit cell for FeTe2O5Br is a = 13.3964(8), b = 6.5966(4), c = 14.2897(6) A, beta=108.118(6) degrees, and Z=8. The layers are built of edge sharing [FeO6] octahedra forming [Fe4O16]20- units that are linked by [Te4O10X2]6- groups. The layers have no net charge and are only weakly connected via van der Waals forces to adjacent layers. There are four crystallographically different Te atoms, and one of them displays a unique [TeO2X] coordination polyhedron (X=Cl, Br). Magnetic susceptibility measurements show a broad maximum typical for 4-spin clusters of coupled Fe(III) ions in the high-spin state. Evidence for magnetic instabilities exists at low temperatures, which have been confirmed with specific heat experiments. A theoretical modeling of the susceptibility concludes a frustration of the intra-tetramer anti-ferromagnetic exchange interaction.     

Synthesis and characterization of Li1.05Co1/3Ni1/3Mn1/3O1.95X0.05 (X = Cl,Br) cathode materials for lithium-ion battery

In order to improve the thermal stability and dynamic performance of LiCo_1/3Ni_1/3Mn_1/3O₂ materials, Cl-doped and Br-doped materials were synthesized via the co-precipitation method. The morphology, structure, electrochemical performance and thermal stability were characterized by environment scanning electron microscopy (ESEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), charge–discharge cycling and differential scanning calorimetry (DSC). Results show that all materials had a stable layered structure with α-NaFeO₂ and that Cl-doping slightly increased the size of grains. Both Cl-doping and Br-doping improved the high rate of discharge capacity, cycle-life performance and thermal stability, but Cl-doping was better than Br-doping in improving the material structure stability, dynamic performance and thermal stability.     

Direct syntheses,characterization and optical analysis of PbX2 (X = I,Br and Cl) nanoparticles without any additives

Lead iodide, bromide and chloride nanoparticles (NP-PbX₂, X = I, Br and Cl) with various morphologies were successfully prepared through a simple hydrothermal method without any additives or stabilizers. By treating the PbX₂ in EtOH/CH₂Cl₂ solution at 170 °C for 12 h, the corresponding PbX₂ nanoparticles were synthesized. The average sizes of PbX₂ nanoparticles were between 30 and 80 nm. The structure, morphology, surface and size of PbX₂ nanoparticles were determined by X-ray diffraction powder, Scanning Electron Microscopy, solid state Photo Luminescent, BET surface area and solid state UV.     

DFT studies on nonlinear optical properties of neutral nest-shaped heterothiometallic [MOS3Py5Cu3X] (M = Mo, W; X = F, Cl, Br, I) clusters

Theoretical calculations were carried out on some neutral nest-shaped heterothiometallic cluster compounds [MOS₃Py₅Cu₃X] (M = Mo, W; X = F, Cl, Br, I) with the high first static hyperpolarizabilities β values. The geometries of these cluster compounds were optimized by the restricted DFT method at B3LYP level with LanL2DZ base set without any constrains. In order to understand the relationship between the first static hyperpolarizabilities and the compositions of these clusters, the frontier orbital compositions and energy gaps between the HOMO and LUMO orbitals were calculated and analysed. In these clusters the HOMO orbitals are mainly composed of halogen atoms and the first static hyperpolarizability increases from F to I atom. The LUMO orbitals of clusters [MoOS₃Py₅Cu₃X] are comprised of Mo, O and S atoms while the LUMO orbitals of clusters [WOS₃Py₅Cu₃X] composed of W atom and pyridine ring. The energy gaps between the HOMO and LUMO orbitals of the clusters [MoOS₃Py₅Cu₃X] are smaller than those of the clusters [WOS₃Py₅Cu₃X]. As a result the first static hyperpolarizability values of the clusters [MoOS₃Py₅Cu₃X] are higher than those of the clusters [WOS₃Py₅Cu₃X].     

Potential energy surface and rate constant of the inversion substitution reactions CH3X + O2 → CH3O2• + X• (X = SH,NO2)

The temperature dependence of the rate constant of the inversion substitution reactions CH₃X + O₂ → CH₃O₂^? + X^? (X = SH, NO₂), can be expressed as k = 6.8 × 10^–12(T/1000)^1.49exp(–62816 cal mol^–1/RT) cm³ s^–1 (X = SH) and k = 6.8 × 10^–12(T/1000)^1.26 × × exp(–61319 cal mol^–1/RT) cm³ s^–1 (X = NO₂), as found with the use of high-level quantum chemical methods and the transition state theory.     

Synthesis,structure, and magnetic properties of bis (3-amino-2-chloropyridinium)tetrahalocuprate(II) [halide = Cl or Br]

The reaction of CuX₂ (X = Cl or Br) with 3-amino-2-chloropyridine in aqueous acids (HX; X = Cl or Br) yields bis(3-amino-2-chloropyridinium)tetrachlorocuprate(II) and bis(3-amino-2-chloropyridinium)tetrabromocuprate(II). Both compounds have been characterized by IR, powder X-ray diffraction, single-crystal X-ray diffraction and temperature dependent magnetic susceptibility. The compounds are isomorphous and exhibit weak antiferromagnetic interactions.     

Die Gadoliniumcarbidhalogenide Gd4C2X3 (X = Cl,Br)

The Gadolinium Carbide Halides, Gd₄C₂X₃ (X = Cl, Br) The compounds Gd₄C₂X₃ (X = Cl, Br) and Tb₄C₂Br₃ have been prepared by reaction of the metals (RE), REX₃, and C in sealed Ta capsules at 1 100° and 1 300°C, respectively. Monophasic samples of Gd₄C₂Br₃ and Tb₄C₂Br₃ were obtained by reacting stoichiometric mixtures of the starting materials for five days. The needle shaped crystals are bronze-coloured and sensitive to air and moisture. Gd₄C₂X₃ crystallizes in the space group Pnma (No. 62) with lattice constants a = 1 059.6(4), b = 368.4(1), c = 1 962.7(8) pm (Gd₄C₂Cl₃), a = 1 084.4(1), b = 373.0(1), c = 2 036.1(1) pm (Gd₄C₂Br₃). According to Guinier photographs, Tb₄C₂Br₃ is isotypic (a = 1 074.3(2), b = 370.6(1), c = 2 019.4(1) pm). In the crystal structure C is octahedrally coordinated by Gd. The Gd₆ octahedra are linked via common edges to form corrugated layers. The X-anions coordinate all free edges and corners of these layers and connect them via Xⁱ? Xⁱ contacts parallel [001]. Gd₄C₂Br₃ shows metallic conductivity. The magnetic susceptibility follows at high temperatures a Curie Weiss law with an effective moment of 7.95 μ_B. At temperatures below 50 K antiferromagnetic order is observed.     

A first-principle study of the stability and electronic properties of halide inorganic double perovskite Cs2PbX6 (X = Cl,I) for solar cell application

The problem of lead toxicity in perovskites materials that are currently performing with the most efficiency can be partially solved by choosing double perovskites compounds Cs₂PbX₆ (X = Cl,I), which have considerably reduced lead contents. These materials are slightly more stable, and substituting Cl and I with Br in small percentages further improves their mechanical stability and electronic properties. In this study, the properties of these promising materials were investigated in their pure and mixed forms.     

Crystal structure of Co(3-pic)2Cl2 and thermal behaviour of a new complex, Co(py)(3-pic)Cl2

A crystalline Co(3-pic)₂Cl₂ compound was obtained and its structure determined by X-ray diffraction. The structure is characterized by the presence of two conformationally different molecules. A new cobalt(II) complex of molecular formula Co(py)(3-pic)Cl₂ was also synthesized. It was characterized by spectroscopic methods (IR, FIR, Raman spectra), elemental analysis and thermogravimetry (TG, DTA, DTG) carried out in both the oxidative and inert atmosphere. Each of the thermal decomposition steps was interpreted and the influence of substituent position in the pyridine ring on the thermal stability of the complex was discussed.     

Syntheses,structures, and characterization of new lead(II)-tellurium(IV)-oxide halides: Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br)

The syntheses, structures, and characterization of four new lead(II)-tellurium(IV)-oxide halides, Pb(3)Te(2)O(6)X(2) and Pb(3)TeO(4)X(2) (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb(3)O(2)Cl(2) or Pb(3)O(2)Br(2) and TeO(2) as reagents. The compounds have three-dimensional structural topologies consisting of lead-oxide halide polyhedra connected to tellurium oxide groups. In addition, the Pb(2+) and Te(4+) cations are in asymmetric coordination environments attributable to their stereoactive lone pair. We also demonstrate that Pb(3)Te(2)O(6)X(2) and Pb(2)TeO(4)X(2) can be interconverted reversibly through the loss or addition of TeO(2). X-ray data: Pb(3)Te(2)O(6)Cl(2), monoclinic, space group C2/m (No. 12), a = 16.4417(11) A, b = 5.6295(4) A, c = 10.8894(7) A, beta = 103.0130(10) degrees, Z = 4; Pb(3)Te(2)O(6)Br(2), monoclinic, space group C2/m (No. 12), a = 16.8911(8) A, b = 5.6804(2) A, c = 11.0418(5) A, beta = 104.253(2) degrees, Z = 4; Pb(3)TeO(4)Cl(2), orthorhombic, space group Bmmb (No. 63), a = 5.576(1) A, b = 5.559(1) A, c = 12.4929(6) A, Z = 4; Pb(3)TeO(4)Br(2), orthorhombic, space group Bmmb (No. 63), a = 5.6434(4) A, b = 5.6434(5) A, c = 12.9172(6) A, Z = 4.     

Metal–metal bonding in metal–string complexes M3(dpa)4X2 (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) from resonance Raman and infrared spectroscopy

Infrared and Raman spectra for metal–string complexes M₃(dpa)₄X₂ (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) are studied. We assign the Ni₃ asymmetric stretching vibration to infrared lines at 304 and 311 cm⁻¹ for Ni₃(dpa)₂Cl₂ and Ni₃(dpa)₂(NCS)₂, respectively. A Raman shift at 242 cm⁻¹ is assigned to the Ni₃ symmetric stretching mode. For Co₃ complexes a line for the Co₃ asymmetric stretching mode appears at 313 and 331 cm⁻¹ for Co₃(dpa)₂Cl₂ and Co₃(dpa)₂(NCS)₂, respectively.     

A systematic computational study on the reactions of dimethyl sulfoxide with XO (X = NO2, Cl, Br and I)

The reactions of dimethyl sulfoxide (DMSO) with XO (X = NO₂, Cl, Br, I) have been studied at CCSD/6-311G(d,p)//B3LYP/6-311G(d,p) level. Two reaction channels have been considered: (1) the oxygen-atom transfer (OAT) from XO (X = NO₂, Cl, Br, I) to DMSO and (2) the hydrogen-abstraction by XO (X = NO₂, Cl, Br, I). The reaction mechanisms of DMSO with NO₃, ClO and BrO are similar: the OAT channel is the dominant channel and DMSO₂ is the primary product; the hydrogen-abstraction channel is not likely to be competitive with the OAT channel. The DMSO + IO reaction, because two reaction channels have the overall negative reaction activation energies and Gibbs free energies, the reaction could occur on both reaction channels. Furthermore, the formation of the stable complex may vary the yield rate of DMSO₂.