Density functional theory investigation of CN on Cu(1 1 1), Ni(1 1 1) and Ni(1 0 0)

The adsorption of CN on Cu(1 1 1), Ni(1 1 1) and Ni(1 0 0) has been investigated using density functional theory (DFT). While experimental studies of CN on Cu(1 1 1) show the molecular axis to be essentially parallel to the surface, the normally-preferred DFT approach using the generalised gradient approximation (GGA) yields a lowest energy configuration with the C-N axis perpendicular to the surface, although calculations using the local density approximation (LDA) do indicate that the experimental geometry is energetically favoured. The same conclusions are found for CN on Ni(1 1 1); on both surfaces bonding through the N atom is always unfavourable, in contrast to some earlier published results of ab initio calculations for Ni(1 1 1)/CN and Ni(1 0 0)/CN. The different predictions of the GGA and LDA approaches may lie in subtly different relative energies of the CN 5σ and 1π orbitals, a situation somewhat similar to that for CO adsorbed on Pt(1 1 1) which has proved challenging for DFT calculations. On Ni(1 0 0) GGA calculations favour a lying-down species in a hollow site in a geometry rather similar to that found experimentally and in GGA calculations for CN on Ni(1 1 0).     

Electron transfer reactions of nickel(III) and nickel(IV) complexes

This review narrates the electron transfer reactions of various nickel(III) and nickel(IV) complexes reported during the period 1981 until today. The reactions have been categorized mainly with respect to the type of nickel complexes. The reactivity of nickel(III) complexes of macrocycles, 2,2′-bipyridyl and 1,10-phenanthroline, peptides and oxime–imine, and of nickel(IV) complexes derived from oxime–imine, oxime and miscellaneous ligands with various organic and inorganic electron donors have been included. Kinetic and mechanistic features associated with such interactions have been duly analyzed. The relevance of Marcus cross-relation equations in the delineation of the electron transfer paths has also been critically discussed.     

Characterization of nonstoichiometric nickel manganite spinels NixMn3−x□3δ/4O4+δ by temperature programmed reduction

Cation deficient spinels Ni_xMn_3−x□_3δ/4O_4+δ (0≤x≤1) have been prepared by thermal decomposition of mixed oxalates Ni_x/3Mn_(3−x)/3(C₂O₄)·nH₂O in air at 623 K. They have been characterised by temperature programmed reduction (TPR) under H₂, the reaction being followed by gravimetric and powder X-ray diffraction measurements. It has been shown that TPR proceeds in several steps. The first steps correspond to the loss of nonstoichiometric oxygen leading to the formation of a stoichiometric oxide. During the following stages the manganese cations are reduced, causing the spinel structure to be destroyed, and the formation of solid solution of NiO in a cubic MnO. Subsequently, Ni²⁺ cations undergo a reduction to metallic nickel, and, finally, a mixture of nonstoichiometric MnO_1−δ and metallic nickel is formed. These oxides contain a high level of vacancies which vary with the nickel content with a maximum of δ≈1 near x=0.6. This nonstoichiometry is ascribed both to the presence of Ni³⁺ and excess of Mn⁴⁺.     

原子吸收光谱法测定铬基合金中钒

本文研究了用原子吸收光谱法，在笑气－乙炔火焰中，测定钒的最佳条件，不用任何分离手段，以铝盐做干扰抑制剂，消除铬，镍对测定钒的干扰，西方法用于铬基合金中钒的测定，方法简单准确，具有实用意义。     

Hybrid inorganic-organic 1-D and 2-D frameworks with {As8V14O42} clusters as building blocks

Three novel hetero-polyoxovanadates, [Cd(2,2′-bpy)₃]{[Cd(dien)]As₈V₁₄O₄₂(H₂O)} (1, 2,2′-bpy=2,2′-bipyridine, and dien=diethylenetriamine), [Zn(2,2′-bpy)₂]₂[As₈V₁₄O₄₂(H₂O)]·H₂O (2) and [Ni(en)₂]₃[As₈V₁₄O₄₂(HPO₃)]·4H₂O (3, en=ethlenediamine), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Crystal data: 1 monoclinic, P2(1)/n, a=15.1728(5), b=19.2863(5), , β=96.005(2)°, Z=4. 2, orthorhombic, P2(1)2(1)2(1), a=12.1270(3), b=15.8678(8), , Z=4. 3, triclinic, , a=12.9340(3), b=13.4130(3), , α=87.170(3)°, β=77.517(3)°, γ=68.480(3)°, Z=2. Compounds 1-3 are all made of the {As₈V₁₄O₄₂} shells linked by corresponding transition metal complexes into extended structures. Compound 1 and 2 present 1-D wave-like and tubular structures, respectively, while compound 3 exhibits a novel 2-D structure containing interwinding puckery layers. Variable temperature susceptibility measurements demonstrate the presence of antiferromagnetic interaction between V^IV cations in 1 and 2.     

高含量钒的钼钒磷杂多化合物的合成和性质研究

本工作改进了文献[4]报导的几种原料同时混合、加热煮沸合成的方法采用分步加入原料,控制反应温度、多次重结晶的方法合成了6、7、8个钒原子取代的钼钒磷杂多酸铵;并以铵盐为原料,用离子交换、冷冻分离和真空抽吸相结合的提纯方法制备了未见文献报导的相应的固体杂多酸;H₅[PMo₅V₇O_37.5]·xH₂O,H₆[PMo₄V₈O_37.5]·xH₂O。通过元素组成分析确定了它们的组成。这些杂多酸在水溶液、非水溶液中的电位滴定表明,杂多阴离子在分解前没有发生自电离、水解等情况,它们在水溶液中是稳定的。酸的碱度分别为5、5、6。通过纸上色谱实验,讨论了杂多酸的分解过程。由热重分析和溶解性实验得到它们的分解温度,本文还讨论了这些化合物的红外、紫外光谱,x光粉末衍射及极谱性质。光谱结果表明,它们可能具有Keggin结构,由导数脉冲极谱得到它们的峰电位。     

方波伏安法测定镍铜合金中的镍含量

在0.01mol·L-1的氨水-氯化铵缓冲溶液(pH 9.3)中,镍(Ⅱ)于-1.25V(vs.SCE)出现一灵敏的方波伏安峰。镍(Ⅱ)浓度在1.5×10-6～1.0×10-4mol·L-1与伏安峰高呈线性关系,线性方程为ip(μA)=2.1870+0.6328c(μmol·L-1),相关系数为0.9991。方法的标准偏差为0.7％。该法应用于镍铜合金样品中镍的测定,结果满意。