High-nuclearity manganese and iron complexes with the anionic ligand methyl salicylimidate

The three novel clusters [Mn6O4(OMe)2(OAc)4(Mesalim)4] (3), [Mn8O2(OH)2(OMe)12(OAc)2(Mesalim)4] (4), and [Fe10O4(OMe)14Cl2(Mesalim)6] (5) have been synthesized from a simple bidentate ligand HMesalim (HMesalim = methyl salicylimidate). Starting from the mononuclear complex [Mn(Mesalim)2(OAc)(MeOH)].MeOH (1), either the hexanuclear complex 3 or the octanuclear complex 4 is obtained after recrystallization, depending upon the reaction conditions and solvents used. Similarly, starting from the purple-colored mononuclear complex [Fe(Mesalim)2Cl] (2), the orange-colored decanuclear iron(III) cluster 5 has been obtained upon recrystallization from methanol. Complex 3, which could also be prepared directly from manganese acetate and the ligand, has a face-sharing double-cubane [Mn6O6] core, unique in transition metal chemistry. Compounds 4 and 5 are composed of [M3O4] partial cubanes. All complexes belong to a class of oxo-bridged cubic close-packed molecular clusters resembling the metal oxide/hydroxide ores. Complex 4 exhibits intramolecular ferromagnetic interactions, as evidenced from dc magnetic susceptibility studies (1.8-300 K), resulting in a high-spin ground state, probably with S(T) = 8. Complex 4 displays single molecule magnet behavior as indicated by frequency and temperature dependences of its ac susceptibility. An Arrhenius plot gave relatively large experimental activation energy of 36.0 K. The magnetic properties of complexes 3 and 5 are dominated by antiferromagnetic interactions leading to zero-spin ground states.     

Gravimetric determination of beryllium with sodium oxinate

Sodium oxinate is found to precipitate Be(II) quantitatively in the pH range 7.5-8.2. The complex has the composition Be(2)O(C(9)H(6)NO)(2).2H(2)O, is stable and can be weighed directly after drying at 105-110 degrees . A method for the estimation of Be(II) and its separation from interfering elements is described. The monohydrate has been prepared from the dihydrate and characterized. The results show the presence of hydroxyl bridges in the monohydrate. Methods using various organic reagents for the direct estimation of beryllium in ores and alloys have been examined and it is found that 4-chloro-2,5-dimethoxyacetoacetanilide gives the best results. A method for the determination of be(II) in beryl without prior separation of Fe(III) and Al(III) is described.     

The role of 70-80% perchloric acid as oxygen donor and the oxidation potentials made available

A study has been made of the probable oxidation potentials provided by perchloric acid in the concentration range 70-80 %. The effect of acid concentration and temperature on the oxidation of chromium, vanadium, cerium, and manganese has been investigated. Available oxidation potentials appear to be 2.0-2.1 V or higher. The monohydrate of perchloric acid, HClO(4).H(2)O, containing 84.6% of perchloric acid, has been made commercially available and authorized for distribution by common carrier. It can be diluted to give acid concentrations from 73.6% (corresponding to HClO(4).2H(2)O) upwards. Perchloric acid mixed with sulphuric acid is equivalent to high concentrations of perchloric acid and can be used for dissolution of ores and destruction of organic matter.     

高钙镁铅锌矿中锌的交流示波极谱滴定

本文阐述了用交流示波极谱滴定法测定高钙镁铅锌矿中的锌。在NH_4Cl—NH_3H_2O(pH=10)支持电解质中采用微银汞膜电极进行实验。分别用NH_4F和铜试剂掩蔽钙、镁、铜、铅、镉及其它竽金属元素。铁和铝不干扰测定。用EDTA滴定锌获得令人满意的结果,对两种矿样分析,准标偏差为0.05%和0.07%。该法快速准确,适用于测定高钙镁的铅锌矿中锌。     

Estimation of chromium in ores and beneficiated products: an ultrasonic approach

Cr(III) slowly forms a violet complex with EDTA at pH 3.5 +/- 0.2 under normal conditions. The complex formation can be catalyzed by irradiating the reacting mixture with ultrasonic waves. Quantitative formation of the complex was possible with ultrasonic waves of 15 W/cm(2) intensity within 7.5 min of sonication. This method may be successfully applied to the determination of chromium in ores and beneficiated products containing 20-60% Cr(2)O(3) without separating the analyte from the matrix elements.     

钼矿石物相分析及催化极谱法测定钼

为测定钼矿中钼的总量,将矿样与盐酸加热后加硝酸-硫酸(8+2)混合酸蒸发冒烟至干。用150 g.L-1氢氧化钠溶液溶解残渣取代了常用的碱融熔法,在所得上清液中测定总钼量。为溶解钼矿中不同相态,另取一份矿样先用氨水处理以溶解钼华矿(MoO3),在每次分相溶解中所得的残渣先后用40 g.L-1酒石酸溶液和150 g.L-1碳酸钠溶液处理依次溶解出钼钨钙矿[Ca(W,Mo)O4]和钼酸铅矿(PbMnO4),在溶解分去钼酸铅矿后的残渣中存在有辉钼矿(MoS2)。将其在580℃灼烧后按测定总钼的溶解方法处理,在所得溶液中测定辉钼矿的钼量。采用催化极谱法测定上述各溶液中的钼量,所用底液为含有氯酸钾、二苯羟乙酸、二苯胍及硫酸的混合液。按所提方法分析了3个钼矿标准样品,所测得每一试样中各物相中钼量之和与该样品的总钼量测定值一致,其相对标准偏差(n=5)均小于3.5%。     

Beneficiation of borax by reverse flotation in boron saturated brine

Flotation is one of the plausible methods for recovering borax fines discharged as fine waste to the tailings dam in the Kirka borax processing plant. A literature review dealing with the flotation behavior of boron minerals reveals that clay minerals in the boron ores coat boron minerals and thus deteriorate the quality of boron concentrates produced by direct flotation. The main objective of this study is therefore to recover borax fines from the tailings of the concentrator by reverse flotation. A three-level-factor experimental design was used to determine the main and interaction effects of variables selected on the metallurgical performance of reverse flotation. An analysis of variance for experimental results indicates that interaction effects of the variables for concentrate quality and recovery of B2O3 is nonsignificant and the most important variable for grade of concentrate and recovery is the collector dosage. It is shown that a concentrate assaying 11.25% B2O3 with 89.90% B2O3 recovery could be produced by means of single-stage (rougher) reverse flotation. Additionally, in order to produce a sufficient-quality concentrate, a multistage reverse flotation scheme involving rougher, scavenger, and two cleaners was devised. A final concentrate containing 23.47% B2O3 with 81.78% B2O3 recovery was obtained from these tests. The reverse flotation method can be thus considered as an important option for the beneficiation of borax fines.     

碳质金矿中金的化学物相分析方法改进

为了解决碳质金矿金化学物相分析结果与选矿试验结果不符的问题,基于岩矿鉴定和测试结果对分析流程进行改进。方法改进后测试项目包括裸露金和半裸露金、有机碳石墨包裹金、碳酸盐包裹金、褐铁矿包裹金、黄铁矿包裹金、石英和硅酸盐包裹金6项。有机碳石墨包裹金选用Na_2S_2O_3–CuCl_2–NH_4OH–NH_4Cl体系为浸金剂,取代I_2–NH_4I体系,该体系中金的测定采用铜置换原子吸收法。裸露金半裸露金、有机碳石墨包裹金和黄铁矿包裹金的相和为82.34%,与选矿试验金精矿实际回收率(75.83%)基本吻合。改进后的方法适合碳质金矿金化学物相分析。     

Spectrophotometric determination of germaninm(IV) with bromopyrogallol red

A method is proposed for the spectrophotometric determination of germanium with Bromopyrogallol Red. A red-violet coloured complex is formed at pH 2-3, with a stoichiometry equivalent to Ge(BPR)(2), and a molar absorptivity of 20.5 x 10(3) at 550 mmu. Beer's law is obeyed over the range 0.2-3 ppm. Germanium in cupriferous ores has been determined by the method.     

AuCl4-H2O2化学发光体系研究

本文发现, AuCl4^-在KOH和H2O2存在下会产生弱化学发光信号; 在此基础上建立了AuCl4^-H2O2-KOH-CTMAB体系测定金的新的简单的化学发光分析法; 方法的检测限为5.5ppbAn; 线性范围为10-800pph; 测定100ppb金溶液的相对标准偏差为6.5%; 并初步探讨了AuCl4^-化学发光的可能过程及表面活性剂的影响作用。     

Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex.

The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores.     

Synthesis and characterization of high nuclearity iron(III) phosphonate molecular clusters

Three new phosphonic acid ligands (4- (t)butylphenyl phosphonic acid, 3,5-dimethylphenyl phosphonic acid, and diphenylmethylphosphonic acid) have been synthesized and employed in search of high molecularity iron(III) clusters. The cluster compounds are characterized by single crystal X-ray diffraction and magnetic measurements. The solvothermal reaction of FeCl 3.6H 2O with diphenylacetic acid and p- (t)butylphenyl phosphonic acid resulted in an unprecedented dodecanuclear cluster [Fe 12(mu 2-O) 4(mu 3-O) 4(O 2CCHPh 2) 14(4- (t)buPhPO 3H) 6]( 1) having a double butterfly like core structure. [Fe 12(mu 2-O) 4(mu 3-O) 4(O 2CPh) 14(C 10H 17PO 3H) 6]( 2), another dodecanuclear cluster having core structure similar to 1, has been synthesized in a reaction between [Fe 3O(O 2CPh) 6(H 2O) 3]Cl and camphylphosphonic acid in the presence of triethylamine at ambient condition. 3,5-Dimethylphenyl phosphonic acid on reacting solvothermally with an oxo-centered iron triangle [Fe 3O(O 2CCMe 3) 6(H 2O) 3]Cl gives a nonanuclear cluster [Fe 9(mu 3-O) 4(O 3PPh(Me) 2) 3(O 2CCMe 3) 13]( 3) having icosahedral type core structure where three positions of the iron atoms have been replaced by phosphorus. Another nonanuclear [Fe 9(O) 3(OH) 3(O 3PCHPh 2) 6(O 2CCMe 3) 6(H 2O) 9] ( 4), having a distorted cylindrical core structure, has been synthesized in a similar solvothermal reaction between [Fe 3O(O 2CCMe 3) 6(H 2O) 3]Cl and biphenylmethyl phosphonic acid. All compounds are characterized by IR spectra, elemental analysis, as well as single crystal X-ray analysis. Magnetic measurements for all the compounds reveal that there are antiferromagnetic interactions between the metal centers.     

Chemistry of borate in salt lake brine (XXXIV) ——Phase diagram of thermodynamic nonequilibrium state of MgO-B_2O_3-18%MgCl_2-H_2O system at 20℃

The crystallization processes of hydrated Mg-borates, boric, magnesium hydroxide and Mg-oxychloride from MgO-B2O3-18%MgCl2-H2O supersaturated solution at 20℃ have been studied by kinetic method. The crystallization solid phases were characterized by X-ray powder diffraction, IR spectra, thermal analysis and chemical analysis. The liquid-solid phase diagram of ther-modynamic nonequilibrium state has been given. In this phase diagram, there exist eight crystallization fields, boric acid(H3BO3), trigomagneborite(MgO · 3B2O3 · 7.5H2O, MgO · 3B2O3 · 7H2O), hungchaoite(MgO ·2B2O3 ·9H2O), inderite(2MgO ·3B2O3 · 15H2O), chloropinnoite(2MgO ·2B2O3 · MgCl2 · 14H2O), magnesium hydroxide(Mg(OH)2) and magnesium oxychloride (5Mg(OH)2 · MgCl2·8H2O).     

Structural variation within homometallic uranium(VI) carboxyphosphonates: in situ ligand synthesis, directed assembly, metal-ligand coordination and hydrogen bonding

Four 2D uranium(VI) carboxyphosphonates, (UO 2)(O 3PCH 2CO 2H) ( 1), (UO 2) 4(HO 3PCH 2CO 2)(O 3PCH 2CO 2) 2(H 2O) 4.3H 2O ( 2), (UO 2)(O 3PCH 2CO 2).NH 4.H 2O (3), and (UO 2) 3(O 3PCH(CH 3)CO 2) 2(O 3PCH(CH 3)CO 2H).2NH 4.H 2O (4) have been prepared using hydrothermal techniques. Their crystal structures have been determined by single-crystal X-ray diffraction, and structural features have been confirmed by infrared spectroscopy. 1, 2, and 3 are constructed from the UO 2 (2+) cation and phosphonoacetate, (O 3PCH 2CO 2), molecules, whereas 4 consists of U(VI) coordinated to 2-phosphonopropionate, (O 3PCH(CH 3)CO 2), units. The thermal and fluorescent behaviors of these materials have also been investigated. The organophosphonate linkers observed in 2 and 4 were produced via the in situ hydrolysis of trialkylphosphonate starting materials.     

Synthesis and characterization of octa- and hexanuclear polyoxomolybdate wheels: role of the inorganic template and of the counterion

Eight new compounds based on [O3PCH2PO3]4- ligands and {MoV2O4} dimeric units have been synthesized and structurally characterized. Octanuclear wheels encapsulating various guests have been isolated with different counterions. With NH4+, a single wheel was obtained, as expected, with the planar CO32- guest, (NH4)12[(MoV2O4)4(O3PCH2PO3)4(CO3)2].24H2O (1a), while with the pyramidal SO32- guest, only the syn isomer (NH4)12[(MoV2O4)4(O3PCH2PO3)4(SO3)2].26H2O (2a) was characterized. The corresponding anti isomer was obtained with Na+ as counterions, Na12[(MoV2O4)4(O3PCH2PO3)4(SO3)2]39H2O (2b), and with mixed Na+ and NH4(+) counterions, Na+(NH4)11[(MoV2O4)4(O3PCH2PO3)4(SO3)2].13H2O (2d). With [O3PCH2PO3]4- extra ligands, the octanuclear wheel Li12(NH4)2[(MoV2O4)4(O3PCH2PO3)4(HO3PCH2PO3)2].31H2O (4a) was isolated with Li+ and NH4+ counterions and Li14[(MoV2O4)4(O3PCH2PO3)4(HO3PCH2PO3)2].34H2O (4c) as a pure Li+ salt. A new rectangular anion, formed by connecting two MoV dimers and two MoVI octahedra via methylenediphosphonato ligands with NH4+ as counterions, (NH4)10[(MoV2O4)2(MoVIO3)2(O3PCH2PO3)2(HO3PCH2PO3)2].15H2)O (3a), and Li9(NH4)2Cl[(MoV2O4)2(MoVIO3)2(O3PCH2PO3)2]. 22H2O (3d) as a mixed NH4+ and Li+ salt have also been synthesized. The structural characterization of the compounds, combined with a study of their behavior in solution, investigated by 31P NMR, has allowed a discussion on the influence of the counterions on the structure of the anions and their stability. Density functional theory calculations carried out on both isomers of the [(MoV2O4)4(O3PCH2PO3)4(SO3)2]12- anion (2), either assumed isolated or embedded in a continuum solvent model, suggest that the anti form is favored by approximately 2 kcal mol(-1). Explicit insertion of two solvated counterions in the molecular cavity reverses this energy difference and reduces it to less than 1 kcal mol(-1), therefore accounting for the observed structural versatility.     

Study on the Reaction Behavior of Some Trinuclear Complexes of Transition Metals: [Fe_2M(μ_3-O) (μ-O_2CCH_3)_6(H_2O)_3]·xH_2O by the Method of Probe Reaction of Acetic Acid

INTRoDUCTIoNRecentlywehaveproposedamethodofchemicalprobereaction(l3forstudyingthereactionbehaviorsoftransitionmetalcomplexes.BythismethodtheserlalresultswereobtainedusingtheC,H, H,OandC2H2 H2astheprobereactions[1~53.Here-inisfurtherpresentedanotherkindoftheprobereaction--theacetoniaztionofaceticacidbydecarboxylationoverfourcomp1exeswithgeneralformula[Fe2M(p3-O)(p-O,CCH,),(H,O),j.xH,O,whereM=Fe(m),Mn(n),Co(I)andNi(n)'whichafterwardswillbedenotedas[Fe2M0AHjforsimplicity(N0te:inthe…     

Intra and intermolecular magnetic interactions in a series of dinuclear Cu(II)/hxta complexes [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: correlation of magnetic properties with geometry

Nine dinuclear copper(II) complexes with hxta5- ligands [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: [Cu2(MeO-hxtaH)(H2O)2] x 4H2O (1), [Na(micro-H2O)2(H2O)6][Cu2(Cl-hxta)(H2O)3]2 x 6H2O (2), [Cu(H2O)6][Cu2(Me-hxta)(H2O)2](NO3) x 2H2O (3), [Cu2(R-hxtaH)(H2O)3] x 3H2O [R = Cl (4), CH3 (5), and MeO (6)], [Cu2(MeO-hxtaH2)(micro-X)(CH3OH)] x 3CH3OH [X = Cl (7), Br (8)] and K5Na(micro-H2O)10[Cu2(micro-CO3)(Me-hxta)]2 x 4H2O (9), have been synthesized and structurally characterized. In complexes 4-7, the dinuclear units are linked via novel pairwise supramolecular interactions involving the ligand carboxylate groups. The intra- and intermolecular magnetic interactions have been quantified, and the coupling constants have been related to the structural geometries.     

高压覆膜制样X射线荧光光谱法测定多金属矿中的多种元素

采用新的制样技术——高压(1800 kN)覆膜(3.6μm Polyester Film)制样,波长色散X射线荧光光谱测定多金属矿中19种组分。该制样技术对高硅锌矿石GBW07237(SiO282.95%),不加黏结剂,也能制出理想的样片。测定结果显示1800 kN制备样品多数组分的灵敏度、精密度和检出限较400 kN制备的样品有所改善。15个多金属矿标准物质建立校准曲线,使用Rh Kα的瑞利散射线作内标测定Cu、Pb、Zn、As和Rh Kα的康普顿散射线作内标测定Sb、Ag、Sn、Bi、Mo及经验系数法校正基体效应。Cu、Pb、Zn、Mn、As、Sb、Ag、Sn、Bi、Mo的测定结果与化学法相符,可同时分析其中的Cd、S、Fe、SiO2、Al2O3、MgO、CaO、Na2O、K2O等成分。实现了固体直接进样测定多金属矿中的多种元素。高压覆膜制样技术是制样技术的突破,国内外尚未见报道。     

熔融制样–X射线荧光光谱法同时测定铀钼矿中主次成分

采用混合熔剂熔融制样,建立了同时测定铀钼矿中U,Mo,SiO_2,Fe_2O_3,Al_2O_3等的X射线荧光光谱法。以Li_2B_4O_7–LiBO_2作为熔融试剂,NH_4NO_3作为样品的氧化剂,样品与熔剂的质量比为1∶10。除使用铀矿石国家标准物质外,主要选取人工混合校准样品及历年实验室比对的铀钼矿校准样品绘制成工作曲线。采用理论系数法校正样品的基体效应,用Br Kα,Zr Kα,U Lα,Ba Lα,Zn Kα谱线扣除相应元素的谱线重叠干扰。该方法各组分测定结果的相对标准偏差均小于2.0%(n=10);用标准物质验证方法的准确度,测定值相对误差在0.00~8.00%之间,与标准值基本吻合。该法应用于生产实验中,可以满足对铀钼矿准确、快速的测量要求。     

Kinetics and mechanism of the reactions of CH3CO and CH3C(O)CH2 radicals with O2. Low-pressure discharge flow experiments and quantum chemical computations

The reactions CH(3)CO + O(2)--> products (1), CH(3)CO + O(2)--> OH +other products (1b) and CH(3)C(O)CH(2) + O(2)--> products (2) have been studied in isothermal discharge flow reactors with laser induced fluorescence monitoring of OH and CH(3)C(O)CH(2) radicals. The experiments have been performed at overall pressures between 1.33 and 10.91 mbar of helium and 298 +/- 1 K reaction temperature. OH formation has been found to be the dominant reaction channel for CH(3)CO + O(2): the branching ratio, Gamma(1b) = k(1b)/k(1), is close to unity at around 1 mbar, but decreases rapidly with increasing pressure. The rate constant of the overall reaction, k(2), has been found to be pressure dependent: the fall-off behaviour has been analysed in comparison with reported data. Electronic structure calculations have confirmed that at room temperature the reaction of CH(3)C(O)CH(2) with O(2) is essentially a recombination-type process. At high temperatures, the further reactions of the acetonyl-peroxyl adduct may yield OH radicals, but the most probable channel seems to be the O(2)-catalysed keto-enol transformation of acetonyl. Implications of the results for atmospheric modelling studies have been discussed.