Hydrothermal Syntheses and Structural Characterizations of Two ML-Containing Polyoxomolybdates:[Cu~Ⅱ_2(HL)_3]_2[Mo_8O_(26)]·(H_2O)_4 and [Ni~Ⅱ(HL)_3]_2(Mo_8O_(26))·(H_2O)_3(HL=3-(2-Pyridyl)pyrazole)

Two new polyoxomolybdate compounds,namely CuII2(HL)3]2[Mo8O26]·(H2O)4(1) and [NiII(HL)3]2(Mo8O26)·(H2O)3(2)(HL = 3-(2-pyridyl)pyrazole),were designed and synthesized under hydrothermal conditions.X-ray diffraction analyses reveal that compound 1 consists of one β-Mo8O264-cluster and a Cu2 dimer which is built from two Cu(II) ions linked by three 3-(2-pyridyl)pyrazole ligands.Compound 2 is generated by two kinds of polyoxomolybdate clusters of α-[Mo8O26]4-and β-[Mo8O26]4-.In complexes 1 and 2,the multi-dimensional frameworks are con-structed with the help of hydrogen-bonding links between the terminaloxygen atoms of [Mo8O26]4-,water molecules,and 3-(2-pyridyl)pyrazole ligands.Crystal data of 1:C24H25Cu2Mo4N9O15,Mr = 1190.37,monoclinic,space group P21/c,a = 10.850(2),b = 18.510(4),c = 17.230(3) ,β = 100.57(3)°,V = 3401.6(12) 3,Z = 4,Dc = 2.324 g/cm3,F(000) = 2312,μ = 2.742 mm-1,R = 0.0302 and wR = 0.0775(Ⅰ 2σ(Ⅰ));Crystal data for 2:C48H48Mo8N18Ni2O29,Mr = 2225.98,monoclinic,space group P21/n,a = 20.799(2),b = 14.7970(13),c = 23.141(2) ,β = 91.6180(10)°,V = 7119.0(11) 3,Z = 4,Dc = 2.077 g/cm3,F(000) = 4344,μ = 1.968 mm-1,R = 0.0309 and wR = 0.0696(Ⅰ 2σ(Ⅰ)).     

An investigation of the Nd2O3-MoO3 phase system: Thermal decomposition of Nd2Mo4O15 and formation of Nd6Mo10O39

A new neodymium molybdate, Nd₆Mo₁₀O₃₉, has been identified in the Nd₂O₃-MoO₃ phase system. Nd₆Mo₁₀O₃₉ appears to be a metastable phase, which does not form directly from a stoichiometric mixture of Nd₂O₃ and MoO₃ oxides. Instead, it can be obtained by thermal decomposition of Nd₂Mo₄O₁₅. Nd₂Mo₄O₁₅ usually decomposes into Nd₂(MoO₄)₃, and the formation of Nd₆Mo₁₀O₃₉ critically depends on the heating regime used.The structure of Nd₆Mo₁₀O₃₉ has been determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group C2/c, with unit cell parameters of , , , β=100.767(2)°, at 120 K. Nd atoms are seven and eight coordinate, and pairs of coordination polyhedra share edges and faces, respectively, to form Nd₂O₁₂ and Nd₂O₁₃ groups. All Mo atoms are in tetrahedral coordination environments, with some of the tetrahedra sharing corners to form pyromolybdate groups.     

An open-framework cobalt molybdate possessing {Mo2O7} building block: hydrothermal synthesis and structural characterization of [CoMo2O7(4,4′-bipy)1.5]

The hydrothermal reaction of Co(COO)₂?·?4H₂O, MoO₃, H₃PO₄ and 4,4′-bipyridine yields bipyridine-ligated cobalt dimolybdate [CoMo₂O₇(4,4′-bipy)_1.5] (1) (4,4′-bipy?=?4,4′-bipyridine) in the triclinic system with space group of P 1 and cell parameters of a?=?7.1951(8)?Å, b?=?11.1708(17)?Å, c?=?11.4514(11)?Å, α?=?98.545(7)°, β?=?90.315(2)°, γ?=?105.777(5)°, V?=?874.88(19)?ų, and Z?=?2. Its structure consists of Co/Mo/O bimetal oxide layers with {Mo₂O₇} building blocks, linked by the coordination of 4,4′-bipy ligand with Co and Mo atoms, into a 3D porous hybrid framework.     

An Improved Spectrophotometric Method for Determination of Penicillins Alone and in Pharmaceutical Dosage Forms

Abstract

A new spectrophotometric method for determining penicillins has been developed. A known volume of the penicillin solution is heated at 95[ddot]C for 70 min with ammonium molybdate, in sulphuric acid medium and the absorbance of the blue species formed is measured at 670 nm. The method has been successfully applied for the determination of thirteen commercially available penicillins. Beer's law is valid for up to 35-90 μg/ml of antibiotic (according to the penicillin). The procedure has been used for analysing some pharmaceutical preparations for these drugs, e.g., injections and capsules. The sensitivity of the method is largely increased with respect to the vanadate method previously described.     

Determination of Phosphorus in Chlorosilanes) And High Purity Silica By Atomic Absorption Spectrophotometer

Abstract

Determination of traces of impurities in chloro-silanes and high purity silica are important in the preparation of semiconductor grade silicon. The author have developed an indirect method for the determination of phosphorus in these materials. Phosphorus is extracted as phosphoantimonyl molybdate complex in methyl isobutyl ketone. The concentration of phorphorus is calculated by determining the concentration of antimony by atomic absorption spectrophotometer as antimony and phosphorus are present in 1:1 molar ratio in the complex. The method is selective and enables the determination of 0.1 ppm of phosphorus.     

钼酸铵分光光度法测定绿茶中的茶多酚

采用钼酸铵分光光度法测定茶叶中的茶多酚含量。它是基于茶多酚在酸性条件下能与钼酸铵反应生成黄色钼酸酯,此物质在341nm处有最大吸收,用分光光度法测其吸光度,从而间接测定茶多酚含量。方法的线性范围为4×10-6～36×10-5g mL,ε=2.1×105L mol·cm,RSD=1 3%(茶多酚含量8×10-6g mL,n=11)。测定结果与标准法基本一致。     

钌（Ⅲ）－钼酸盐－耐尔蓝－PVA＿（124）体系缔合显色反应的研究

在聚乙烯醇存在下，钌与铜酸盐和耐尔蓝（ＮＢ）形成离子缔合物，缔合物的λ＿（ｍａｘ）为５８５ｎｍ，ε为１．３２×１０￣６Ｌ·ｍｏｌ·ｃｍ￣（－１），符合比耳定律范围０～１．２μｇ／２５ｍＬＲｕ，检测限为２．６ｎｇ／ｍＬ（ｎ＝１１），用平衡移动法测定缔合物的摩尔比为Ｒｕ：ＮＢ＝１：２。考察了４３种共存离子的影响，仅Ｏ＿ｓ（Ⅲ）、、Ａｓ（Ⅲ）、Ｓｂ（Ⅲ）、Ｇｅ（Ⅳ）有干扰，需用蒸馏分离。本法已用于某些岩矿和冶金产品中钌的测定，结果满意。     

用钼酸盐和罗丹明B光度法测定铂

本文研究了在聚乙烯醇（ＰＶＡ）存在下用钼酸盐和罗丹明Ｂ（ＲＢ）光度法测定铂，铂（Ⅳ）与相酸铵和罗丹明Ｂ形成离子缔合物，它的最大吸收波长位于５７０ｎｍ处；摩尔吸光系数６值为６．８３×１０￣５Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１），铂量在０～３．５μｇ／２５ｍＬ范围内服从比耳定律，缔合物至少稳定１月。报告了４１种共存离子的影响，除生成杂多酸元素和Ａｕ（Ⅲ）、Ｏｓ（Ⅷ）、Ｒｕ（Ⅲ）外，大多数元素不干扰。测定铂（Ⅳ）的适宜条件为［ＨＣｌＯ＿４］＝０．９３ｍｏｌ／Ｌ，［ＲＢ］＝４．２×１０￣（－５）ｍｏｌ／Ｌ，ＰＶＡ０．８ｇ／Ｌ，本法已用于催化剂和某些铂矿中铂的测定，结果满意。缔合物的摩尔比为Ｐｔ（Ⅳ）：ＲＢ＝１：２，初步探讨了反应机理。     

Ln2Mo3O9的制备,结构及电磁性质

Ｌｎ＿２Ｍｏ＿３Ｏ＿９的制备、结构及电磁性质史发年，任玉芳，孟建（中国科学院长春应用化学研究所稀土化学与物理开放实验室长春１３００２２）关键词稀土钼酸盐，结构，电学性质，磁学性质高氧化态Ｍｏ￣（６＋）与稀土的复合氧化物研究得较多￣［１～４］，而低氧化...     

用罗丹明B和钼酸铵水相光度法测定痕量锇

本研究在聚乙烯醇存在下，锇与钼酸铵形成络阴离子，继而与罗丹明Ｂ（ＲＢ）形成离子缔合物，该缔合物的摩尔吸光系数ε值为２．６２×１０＾６Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，性范围０－１．２μｇ／２５ｍＬ，检测限为１．３ｎｇ／ｍＬ（ｎ＝８），ＲＳＤ为２．２％（ｎ＝７），缔合物稳定４周，考察了３０多种共存离子的影响，除贵金属和能形成杂多酸的元素外，大多数贱金属不干扰。方法已用于测定某些催化剂和岩矿中的锇，结果