Thermodynamic Properties of Quaternary Aqueous Solutions of Chlorides Charge-type 1-1*1-1*2-1: NH4Cl + NaCl + YCl2 + H2O with Y ≡ Mg2+, Ca2+, and Ba2+

Thermodynamic properties of quaternary aqueous solutions of mixed chlorides of 1-1*1-1*2-1 charge type with the cations (Na⁺, NH₄ ⁺; Mg²⁺, Ca²⁺, Ba²⁺) were determined using the hygrometric method. The quaternary systems NH₄Cl + NaCl + MgCl₂ + H₂O, NH₄Cl + NaCl + CaCl₂+ H₂O, and NH₄Cl + NaCl + BaCl₂ + H₂O have been studied at 25 °C. The water activities were measured at total molalities from 0.44 mol⋅kg⁻¹ to saturation for different ionic-strength fractions y of NH₄Cl, y=(0.20,0.50,0.80), and different ionic strength ratios z for other solutes, z=(0.20,0.50 and 0.80) for each value of y. The obtained data allows the calculation of osmotic coefficients.     

Synthesis, structure, and properties of M[VO2(XO4)(H2O)2] · H2O (X = S, M = K, Rb, NH4, Tl; X = Se, M = K, Rb, NH4)

Keeping of MVO(XO₄)₂ under saturated vapor pressure at room temperature resulted in the synthesis of a number of isostructural complexes M[VO₂(XO₄)(H₂O)₂] · H₂O, where X = S, M = K, Rb, NH₄, Tl and X = Se, M = K, Rb, NH₄. The conclusion about the isostructural nature of the synthesized sulfate and selenate compounds was based on X-ray diffraction and vibrational spectroscopy data. Characteristic features of the thermal decomposition of M[VO₂(XO₄)(H₂O)₂] · H₂O on heating in air were identified. It was shown that K[VO₂(SeO₄)(H₂O)₂] · H₂O tends to undergo spontaneous dehydration under ambient conditions to give the monohydrate K[VO₂(SeO₄)(H₂O)].     

Magnetic properties of fullerene salts containing d- and f-metal cations (Co2+, Ni2+, Fe2+, Mn2+, Eu2+, Cd2+). Specific features of the interaction between C60·? and the metal cations

The interaction between the radical anions C₆₀ ^·− and divalent d- and f-metal (Co, Fe, Ni, Mn, Eu, Cd) cations in DMF and acetonitrile-benzonitrile (AN-BN) mixture was studied. Black solid polycrystalline salts (C₆₀ ^·−)₂{(M²⁺)(DMF) _x } (x = 2.4–4, 1–6) containing the radical anions C₆₀ ^·− and metal(ii) cations solvated by DMF were prepared for the first time and their optical and magnetic properties were studied. The salts containing Co²⁺, Fe²⁺, and Ni²⁺ are characterized by antiferromagnetic interactions between the radical anions C₆₀ ^·−, which result in unusually large broadening of the EPR signal of C₆₀ ^·− upon lowering the temperature (from 5.55–12.6 mT at room temperature to 35–40 mT at 6 K for Co²⁺ and Ni²⁺). The salts containing Mn²⁺ and Eu²⁺ form diamagnetic dimers (C₆₀ ⁻)₂, which causes a jumpwise decrease in the magnetic moment of the complexes and disappearance of the EPR signal of C₆₀ ^·− in the temperature range 210–130 K. A feature of salt 6 is magnetic isolation of the radical anions C₆₀ ^·− due to the presence of diamagnetic cation Cd²⁺. The salts prepared are unstable in air and decompose in o-dichlorobenzene or AN. Reactions of C₆₀ ^·− with metal(ii) cations in AN-BN mixture result in decomposition products of the salts that contain neutral fullerene dimers and metals solvated by BN. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1909–1919, September, 2008.     

Heterometallic complexes of Co2+, Ni2+, and Zn2+ with the [RuNO(NO2)4OH]2? anion and pyridine: Synthesis, crystal structure, and thermolysis

Three new heteronuclear complexes [Ru(NO)(NO₂)₄(OH)M(Py)₃] (M = Co²⁺, Ni²⁺, Zn²⁺) were synthesized and structurally characterized. In all compounds, the [Ru(NO)(NO²)⁴(OH)] fragment is coordinated to the M atom by a bridging OH and two bridging NO₂ groups. The coordination environment of the metal also includes three pyridine nitrogen atoms. Thermal decomposition of cobalt and nickel complexes in an inert atmosphere yields bimetallic solid solutions. Original Russian Text ? G.A. Kostin, A.O. Borodin, Yu.V. Shubin, N.V. Kurat’eva, V.A. Emelyanov, P.E. Plyusnin, M.R. Gallyamov, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 1, pp. 57–64.     

Effect of non-aqueous solvents on stoichiometry and selectivity of complexes formed between 4′-nitrobenzo-15-crown-5 with Fe3+, Y3+, Cd2+, Sn4+, Ce3+ and Au3+ metal cations

The complexation processes between Fe³⁺, Y³⁺, Cd²⁺, Sn⁴⁺, Ce³⁺ and Au³⁺ metal cations with macrocyclic ligand, 4′-nitrobenzo-15-crown-5 (4′NB15C5), were studied in acetonitrile (AN), methanol (MeOH) and nitromethane (NM) solvents at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between this macrocyclic ligand and Cd²⁺, Au³⁺ cations is 1: 1 (ML), but in the case of Fe³⁺, Y³⁺ and Ce³⁺ metal cations, 2: 1 (M₂: L) and 2: 2 [M₂: L₂] complexes are formed in nitromethane solutions. The results show, that the selectivity of 4’NB15C5 for the studied metal cations in methanol solutions at 15°C is: Sn⁴⁺ > Cd²⁺ > Y³⁺ > Fe³⁺ ∼ Ce³⁺ > Au³⁺, but in the case of acetonitrile, the stability order was found to be: Y³⁺ > Au³⁺ > Fe³⁺ > Cd²⁺. The values of stability constants of the 1: 1 [M: L] complexes were determined from conductometric data using a GENPLOT computer program. The values of thermodynamic parameter (ΔH _c ^o and ΔH _c ^o) for formation of the complexes were obtained from temperature dependence of the stability constants, using the van’t Hoff plots. The results show that the values of standard enthalpy (ΔH _c ^o) and standard entropy (ΔH _c ^o) change with the nature of the non aqueous solvents.     

Syntheses of the eight-coordinate NH4[ErIII(Cydta)(H2O)2] · 4.5H2O and (NH4)2[Er 2III (Pdta)2(H2O)2] · 2H2O complexes and their structural investigation

In this work, the title complexes, NH₄[Er^III(Cydta)(H₂O)₂] · 4.5H₂O (I) (H₄Cydta = trans-1,2-cyclo-hexanediamine-N,N,N′,N′-tetraacetic acid) and (NH₄)₂[Er₂^III(Pdta)₂(H₂O)₂] · 2H₂O (II) (H₄Pdta= propylene-diamine-N,N,N′,N′-tetraacetic acid), were prepared, respectively, and their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. Complex I selects a mononu-clear structure with pseudosquare antiprismatic geometry crystallized in the triclinic crystal system with space group $ P\bar 1 $ P\bar 1 and the central Er³⁺ ion is eight-coordinated by the hexadentate Cydta ligand and two water molecules. The crystal data are as follows: a = 8.568(3), b = 10.024(3), c = 14.377(4) ?, α = 88.404(4)°, β = 75.411(4)°, γ = 88.332(4)°, V = 1194.2(6) ?³, Z = 1, ρ _c = 1.793 g/cm³, μ = 3.586 mm⁻¹, F(000) = 648, R = 0.0257, and wR = 0.0667 for 4169 observed reflections with I ≥ 2σ(I). Complex II is eight-coordinated as well, which selects a binuclear structure with two pseudosquare antiprismatic geometry and crystallizes in the monoclinic crystal system with space group P2₁/n. The central Er³⁺ ion is coordinated by two nitrogens and four oxygens from one hexadentate Pdta ligand. Besides, two oxygens come from one carboxylic group of the neighboring Pdta ligand and one water molecule, respectively. The crystal data are as follows: a = 12.7576(8), b = 9.3151(6), c = 14.3278(9) ?, β = 96.1380(10)°, V = 1692.93(19) ?³, Z = 4, ρ _c = 2.054 g/cm³, μ = 5.015 mm⁻¹, F(000) = 1028, R= 0.0228, and wR = 0.0534 for 2984 observed reflections with I ≥ 2σ(I).     

A theoretical study of cation--π interactions: Li+, Na+, K+, Be2+, Mg2+ and Ca2+ complexation with mono- and bicyclic ring-fused benzene derivatives

DFT (B3LYP functional) and MP2 methods using 6-311+G(2d,2p) basis set have been employed to examine the effect of ring fusion to benzene on the cation--π interactions involving alkali metal ions (Li⁺, Na⁺, and K⁺) and alkaline earth metal ions (Be²⁺, Mg²⁺ and Ca²⁺). Our present study indicates that modification of benzene (π-electron source) by fusion of monocyclic or bicyclic (or mixture of these two kinds of rings) strengthens the binding affinity of both alkali and alkaline earth metal cations. The strength of interaction decreases in the following order: Be²⁺ > Mg²⁺ > Ca²⁺ > Li⁺ > Na⁺ > K⁺ for any considered aromatic ligand. The interaction energies for the complexes formed by divalent cations are 4–6 times larger than those for the complexes involving monovalent cations. The structural changes in the ring wherein metal ion binds are examined. The distance between ring centroid and the metal ion is calculated for all of the complexes. Strained bicyclo[2.1.1]hexene ring fusion has substantially larger effect on the strength of cation--π interactions than the monocyclic ring fusion for all of the cations due to the π-electron localization at the central benzene ring.     

Crystal structures of seven-coordinate (NH4)2[MnII(edta)(H2O)]·3H2O, (NH4)2[MnII(cydta)(H2O)]·4H2O and K2[MNII(hdtpa)]·3.5H2O complexes

The title compounds, (NH₄)₂[Mn^II(edta)(H₂O)]·3H₂O (H₄edta = ethylenediamine-N,N,N′,N′-tetraacetic acid), (NH₄)₂[Mn^II(cydta)(H₂O)]·4H₂O (H₄cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and K₂[Mn^II(Hdtpa)]·3.5H₂O (H₅dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), were prepared; their compositions and structures were determined by elemental analysis and single-crystal X-ray diffraction technique. In these three complexes, the Mn²⁺ ions are all seven-coordinated and have a pseudomonocapped trigonal prismatic configuration. All the three complexes crystallize in triclinic system in P-1 space group. Crystal data: (NH₄)₂[Mn^II(edta)(H₂O)]·3H₂O complex, a = 8.774(3) ?, b = 9.007(3) ?, c = 13.483(4) ?, α = 80.095(4)°, β = 80.708(4)°, γ = 68.770(4)°, V = 972.6(5) ?³, Z = 2, D _c = 1.541 g/cm³, μ = 0.745 mm⁻¹, R = 0.033 and wR = 0.099 for 3406 observed reflections with I ≥ 2σ(I); (NH₄)₂[Mn^II(cydta)(H₂O)]·4H₂O complex, a = 8.9720(18) ?, b = 9.4380(19) ?, c = 14.931(3) ?, α = 76.99(3)°, β = 83.27(3)°, γ = 75.62(3)°, V = 1190.8(4)?³, Z = 2, D _c = 1.426 g/cm³, μ = 0.625 mm⁻¹, R = 0.061 and wR = 0.197 for 3240 observed reflections with I ≥ 2σ(I); K₂[Mn^II(Hdtpa)]·3.5H₂O complex, a = 8.672(3) ?, b = 9.059(3) ?, c = 15.074(6) ?, α = 95.813(6)°, β = 96.665(6)°, γ = 99.212(6)°, V = 1152.4(7) ?³, Z = 2, D _c = 1.687 g/cm³, μ = 1.006 mm⁻¹, R = 0.037 and wR = 0.090 for 4654 observed reflections with I ≥ 2σ(I). Original Russian Text Copyright ? 2008 by X. F. Wang, J. Gao, J. Wang, Zh. H. Zhang, Y. F. Wang, L. J. Chen, W. Sun, and X. D. Zhang The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 753–759, July–August, 2008.     

Fe3+/Ba2+/Co2+/Zn2+/Cu2+在NH4HCO3-NH3·H2O和NaOH-Na2CO3体系中的热力学分析

通过对Fe3+/Ba2+/Co2+/Zn2+/Cu2+在NH4HCO3-NH3·H2O和NaOH-Na2CO3体系中的热力学分析,得到各金属离子总浓度(cMe)与pH值的关系,确定了2种体系中5种离子完全共沉淀的pH值范围.结果表明:在NH4HCO3-NH3·H2O体系中,Co2+、Zn2+、Cu2+3种离子和氨的配位能力很强,其中Cu2+与氨的配位能力最强,在相同的pH值条件下,Cu2+沉淀困难,5种金属离子的完全共沉淀区域由Cu2+决定.在NaOH-Na2CO3体系中,随总碳浓度(cc)的增加,Ba、Co、Zn、Cu的溶解度都随之减小,当cc=1.0 mol·L-1时,各金属离子完全共沉淀的pH值范围为7.5～11.在两种体系中,Fe的溶解度都是随pH值的增大而减小,最终达到平衡.以NaOH-Na2CO3 为沉淀剂.在pH=10.0的条件下,采用化学共沉淀法合成出了晶粒细小、粒度均匀的Y型纯相结构的平面六角铁氧体微粉.     

Synthesis and structure of gold and copper complexes: [Ph3PhCH2P]+[AuCl4]?, [NH(C2H4OH)3]+[AuCl4]? · H2O, and [Ph3EtP] 2+ [Cu2Cl6]2?

Triphenylbenzylphosphonium tetrachloroaurate (I) and triethanolammonium tetrachloroaurate hydrate (II) were prepared by reacting tetrachloroauric acid in acetone with triphenylbenzylphosphonium and triethanolammonium, respectively. Triphenylethylphosphonium hexachlorodicuprate (III) was synthesized from triphenylethylphosphonium chloride and copper chloride in acetone. The crystal structures of complexes I to III were determined by single-crystal X-ray diffraction. The phosphorus atoms in complex I have a nearly undistorted tetrahedral coordination (CPC, 108.3°–110.6°; P-C, 1.788–1.793 ?). The coordination of nitrogen atoms in the cations of complex II is a distorted tetrahedron (CNC, 111.7°–112.4°). The square coordination of aurum in I and II is only slightly distorted: the ClAuCl angles are 89.6°–90.3° (I) and 89.5°–90.6° (II) and the Au-Cl distances are 2.256–2.278 ? I) and 2.280–2.285 ? (II). The phosphorus atoms in complex III are tetracoordinated (CPC, 106.34°–111.73°; P-C, 1.790–1.795 ?). The copper atoms in III have a distorted tetrahedral coordination (ClCuCl, 98.48°–144.85°; Cu-Cl, 2.1999–2.3263 ?). The central fragment Cu₂Cl₂ in the anion of complex III is bent relative to the Cu₂ axis (the chlorine atom deviates from the Cu₂Cl plane by 0.27 ?).     

Syntheses, characterization, and structure determination of nine-coordinate Na[YIII(edta)(H2O)3]· 5H2O and eight-coordinate Na[YIII(cydta)(H2O)2]·5H2O complexes

Syntheses and structure determination of the Y^III complexes with ethylenediaminetetraacetic acid (H₄edta) and trans-1,2-cyclohexanediaminetetraacetic acid (H₄cydta) are reported. The crystal and molecular structures of the complexes, as well as their molecular formulas and compositions, were determined by single-crystal X-ray structure analyses, NMR, IR, thermogravimetric measurements, and elementary analyses. The crystal of the Na[Y^III(edta)(H₂O)₃]·5H₂O complex belongs to the orthorhombic crystal system and space group Fdd2. The crystal data are as follows: a = 19.355(5) Å, b = 35.431(11) Å, c = 12.122(3) Å, V = 8313(4) ų, Z = 16, M = 544.23, D_c = 1.739 g·cm⁻³, μ = 2.908 mm⁻¹ and F(000) = 4480. The final R and Rw are 0.0483 and 0.1172 for 3284 (I > 2σ(I)) unique reflections, R and Rw are 0.0678 and 0.1440 for all 8499 reflections, respectively. The Y^IIIN₂O₇ part in the [Y^III(edta)(H₂O)₃]⁻ complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure, in which the six coordinated atoms (two N and four O) from the edta ligand and three water molecules are coordinated to the central Y^III ion directly. The crystal of the Na[Y^III(cydta)(H₂O)₂]·5H₂O complex belongs to the triclinic crystal system and space group. The crystal data are as follows: a = 8.405(2) Å, b = 9.970(2) Å, c = 14.763(4) Å, α = 88.538(4)°, β = 76.193(4)°, γ = 88.100(4)°, V = 1200.6(5) Å ³, Z = 2, M = 580.31, D_c = 1.605 g·cm⁻³, μ = 2.519 mm⁻¹ and F(000) = 600. The final R and Rw are 0.0381 and 0.0911 for 4198 (I > 2σ(I)) unique reflections, R and Rw are 0.0530 and 0.1041 for all 6186 reflections, respectively. The Y^IIIN₂O₆ part in the [Y^III(cydta)(H₂O)₂]⁻ complex anion has a pseudo square antiprismatic eight-coordinate structure in which the six coordinated atoms (two N and four O) from the cydta ligand and two water molecules are coordinated to the central YIII ion directly. Original Russian Text Copyright ? 2005 by J. Wang, Y. Wang, Zh. H. Zhang, X. D. Zhang, J. Tong, X. Zh. Liu, X. Y. Liu, Y. Zhang, and Zh. J. Pan __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 5, pp. 928–938, September–October, 2005.     

Theoretical Study on Stereodynamics of Reactions of N(2D)+H2→NH+H and N(2D)+D2→ND+D

The vector correlations between products and reagents for the title reactions have been calculated by the quasi-classical trajectory method at a collision energy of 21.32 kJ/mol on an accurate potential energy surface of Ho et al. (J. Chem. Phys. 119, 3063 (2003)). The peaks of the product angular distribution are found to be in both backward and forward directions for the two title reactions. The product rotational angular momentum is not only aligned, but also oriented along the negative direction of y-axis. These theoretical results are in good agreement with recent experimental findings for the two title reactions. The isotopic effect is also revealed and primarily attributed to the difference of the mass factor in the two title reactions.     

Theoretical studies on N-loss predissociation mechanisms of N2O+ (A?2Σ+) in Cs symmetry

The N-loss predissociation mechanisms of the A ²Σ⁺ (2 ² A′) state of N₂O⁺ to the first and second dissociation limits were studied in the C _s symmetry. The potential energy curves (PECs) and minimum energy crossing points (MECPs) for the C _s states of N₂O⁺ were calculated at the CAS levels. On the basis of our CAS calculation results (CASPT2 energetic results and CASSCF spin orbit couplings), we suggest two processes for N-loss predissociation mechanisms of A ²Σ⁺ (2 ² A′) to the first and second limits. The first two steps in the two processes are the same: A ²Σ⁺ passes through the 2 ² A′/1 ⁴ A″ MECP and then reaches the 1 ⁴ A″ (1 ⁴Σ⁻) PEC. The 2 ² A′/1 ⁴ A″ MECP has a bent geometry and is slightly higher in energy than the transition state along the 1 ⁴ A″ PEC. Our mechanisms are different from the previously suggested mechanisms (via 1 ⁴Π).     

锂离子电池用新型MV3O8（M=Li+,Na+,NH4+）嵌锂材料

本文详细综述了近年来国内外关于锂离子电池三钒酸盐嵌锂电极材料的研究进展,重点对钒酸锂、钒酸钠和钒酸铵材料的晶体结构、充放电机制、合成及电化学性能研究等进行了介绍,并结合我们课题组的研究情况,对比分析了上述三种材料的优劣。钒酸锂是目前研究的热点,近年来随着新型制备工艺的引入以及包括掺杂包覆改性手段的应用,材料的循环性能得到明显改善,但是相对较差的结构属性限制了其进一步的研究与应用;钒酸钠有较稳定的层状结构,体现了优秀的循环稳定性能和倍率性能,在高功率长寿命有机电解液锂电池正极材料以及水溶液锂电池负极材料的应用中有广阔的前景;相比于钒酸锂,钒酸铵材料具有合成方法更简单、比容量相当、循环性能更优越的特点,分子内氢键的存在使得层状结构更加稳定,该材料有望成为钒系材料中新的研究热点。     

用离散-连续模型计算NH2-,NH3和NH4+的溶剂化自由能

通过理论计算推测NH2-,NH3和NH4+在水溶液第一溶剂化层中与之直接作用的水分子分别为2,4和4个,并采用离散-连续模型计算了NH2-,NH3,NH3和NH4+在水溶液中的溶剂化自由能.结果表明,由于离散-连续模型在从头算水平考虑了溶质分子与第一溶剂化层溶剂分子之间的作用,能更准确地描述溶剂化作用.此外,采用更加符合溶液中真实情况的溶剂化构型,能得到更准确的溶剂化性质.     

亚甲基蓝及NH4+,Na+,K+与SiO2的表面配位常数测定

采用动电位、等温吸附方法研究了不同pH条件下SiO2的表面电性和对有机染料-亚甲基蓝的吸附行为,运用WinSGW软件计算得出亚甲基蓝在SiO2颗粒表面配位常数.研究发现亚甲基蓝通过静电和氢键作用吸附,相应的化学反应模型和表面配位常数分别为≡Si2O-+MB+≡Si2OMB(lg K=4.48)和≡SiOH+MB+≡SiOHMB+(lg K=2.30).在此基础上研究了一价阳离子NH+4,Na+,K+对亚甲基蓝在SiO2表面吸附的影响,根据WinSGW软件模拟得到的NH+4,Na+,K+与SiO2表面的配位常数分别为:≡Si2O-+M+≡Si2OM[lg K=3.76,2.73,2.58(M+=NH+4,Na+,K+).在铵根离子浓度高时,还会在表面上发生≡SiOH+NH3+MB+≡SiOHNH3MB+(lg K=6.69)化学反应而生成包含有三种组分的≡SiOHNH3MB+表面三元配合物.研究结果可为了解有机染料和氨氮在被污染土壤和水体中的分布提供一定的理论依据.     

New nine-coordinate (NH4)3[YbIII(ttha)]·5H2O and eight-coordinate (NH4)[YbIII(pdta)(H2O)2]·5H2O complexes: Structural determination

The (NH₄)₃[Yb^III(ttha)]·5H₂O (I) (H₆ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (NH₄)[Yb^III(pdta)(H₂O)₂]·5H₂O (II) (H₄pdta = propylenediamine-N,N,N′,N′-tetraacetic acid) complexes are synthesized by heat-refluxing and acidity-adjusting methods, and their structures are determined by single crystal X-ray diffraction techniques. These two complexes are all mononuclear structures. The complex I crystallizes in ttha monoclinic crystal system with the P2₁/c space group. The central Yb^III ion is nine-coordinated only by one the ligand, and one non-coordinate carboxyl group is left. The crystal data are as follows: a = 10.321(4) ?, b = 12.744(5) ?, c = 23.203(9) ?, β = 91.082(6)°, V = 3051(2) ?³, Z = 4, D _c = 1.754 g/cm³, μ = 3.150 mm⁻¹, F(000) = 1636, R = 0.0357, and wR = 0.0672 for 6203 observed reflections with I ≥ 2σ(I). The YbN₄O₅ part in the [Yb^III(ttha)]³⁻ complex anion forms a pseudo-monocapped square antiprismatic polyhedron. The complex II is coordinated with one pdta ligand and two water molecules, which form an eight-coordinate structure, and crystallizes in the triclinic crystal system with the P[`1]P\bar 1 space group. The YbN₂O₆ part in the [Yb^III(pdta)(H₂O)₂]⁻ complex anion makes a pseudo-square antiprismatic polyhedron. The crystal data are as follows: a = 9.8923(9)?, b = 10.9627(10) ?, c = 12.2618(11) ?, α = 67.284(5)°, β = 70.956(6)°, γ = 68.741(5)°, V = 1115.97(18) ?³, Z = 2, D _c = 1.843 g/cm³, μ = 4.264 mm⁻¹, F(000) = 618, R = 0.0177, and wR = 0.0409 for 4036 observed reflections with I ≥ 2σ(I).     

Chemical bonding and properties in [Ni(N-heterocylic carbene)(NO)(R)] (R = H, Me, HC=CH2, and C≡CH) complexes: Theoretical insights

A series of N-heterocyclic carbene nickel complexes of the type [Ni(N-heterocylic carbene)(NO)(R)] (R = H, Me, HC=CH₂, and C≡CH) are examined to study the influence of a substituent on the molecular structure and bonding of these complexes. Geometrical and AIM analyses of the interaction between Ni and the carbene fragment reveal that for the metal-carbene bond donation is more important than back-donation. The NICS values suggest that aromaticity in the heterocyclic ring is less than in the free heterocycle.     

Syntheses and crystal structures of nine-coordinate K2[EuIII(dtpa)(H2O)]·5H2O and Na2[TbIII(Httha)]·6H2O complexes

The title complexes, K₂[Eu^III(dtpa)(H₂O)]·5H₂O (H₅dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), Na₂[Tb^III(Httha)]·6H₂O (H₆ttha = triethylenetetramine-N,N,N′,N′,N″,N″-hexaacetic acid), were prepared, and their compositions and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. The crystal of K₂[Eu^III(dtpa)(H₂O)]·5H₂O belongs to triclinic crystal system and $ P\bar 1 $ P\bar 1 space group. The crystal data are as follows: a = 8.3540(17), b = 10.147(2), c = 15.059(3) α = 84.63(3)?, β = 82.02(3)°, γ = 83.96(3)°, V = 1253.1(4)?³, Z = 2, R = 0.0325 and wR = 0.1013 for 4407 observed reflections with I ≥ 2σ(I). The [Eu^III(dtpa)(H₂O)]²⁻ has a nine-coordinate pseudo-monocapped square antiprismatic structure, in which the nine coordinate atoms, three N and six O are from one dtpa ligand and one water molecule. The crystal of the Na2[Tb^III(Httha)]·6H₂O belongs to monoclinic system and P2₁/c space group. The crystal data are as follows: a = 10.3976(10), b = 12.7908(13), c = 23.199(2) ? = 90.914(2)°, V = 3084.9(5)?³, Z = 4, R = 0.0309 and wR = 0.0704 for 5429 observed reflections with I ≥ 2σ(I). In the [Tb^III(Httha)]²⁻, the Tb³⁺ ion is nine-coordinated yielding a pseudo-monocapped square antiprismatic conformation, in which the ttha ligand coordinates to the central Tb³⁺ ion with four N atoms and five O atoms. There is a free non-coordinate carboxyl group (−CH₂COOH) that can be modified by some biological molecules having target function.     

Ab initio study of the structure and stability of ThF n(4?n)+ complexes (n = 1–8)

The structural and energetic characteristics of ThF _n ⁽⁴⁻ⁿ⁾⁺ (n = 1–8) complexes have been calculated by the ab initio RHF and MP2 methods.