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991.
An improved flow-injection system for spectrophotometric determination of molybdenum and tungsten in tool steels 总被引:1,自引:0,他引:1
A flow-injection procedure for simultaneous spectrophotometric determination of tungsten and molybdenum in steel alloys is proposed. The method exploits the catalytic effects of Mo(VI) and W(VI) on the rate of iodide oxidation by hydrogen peroxide under acidic conditions. A novel strategy for ion-exchange separation of the potential interfering species is proposed, and an AG50W-X8 cationic resin mini-column is used. The sample is injected twice, originating two sequential plugs, citrate being added to one of them in order to suppress the W(VI) catalytic activity thus providing the kinetic discrimination.The system handles 70 samples per hour and requires 1.6 mg KI per determination. A linear response is verified up to 10 mg l−1 Mo (or W) in the injectate, and signal additivity is 98-103%. Results are precise (R.S.D. < 0.04) and in agreement with ICP-OES. Running a standard reference material (IPT-50) assessed also accuracy. 相似文献
992.
Ankush V. Biradar 《Tetrahedron letters》2008,49(22):3616-3619
The molybdenum acetylide oxo-peroxo complex obtained in situ by the treatment of the corresponding molybdenum acetylide carbonyl complex, CpMo(CO)3(CCPh); Cp = η5-C5H5 with H2O2, has been used as an efficient catalyst for selective N-oxidation of primary amines to nitroso derivatives. Excellent amine conversion (up to 100%) and very high selectivity for nitroso compounds (99%) have been obtained using 30% hydrogen peroxide as an oxidant. The oxo peroxo Mo(VI) complex has also been found to be very active for the oxidation of various substituted primary aromatic amines with electron donating as well as electron withdrawing substituents on the aromatic ring. 相似文献
993.
两次双波长分光光度法同时测定钼和钨的研究 总被引:6,自引:0,他引:6
本文把等吸收双波长法和双峰双波长法结合起来。建立了一种新型高灵敏度的同时测定铝、钨的两次双波长光度法。测定Mo、W的摩尔吸光系数分别为1.9×10~5和1.7×10~5L·mol~(-1).cm~(-1),测定范围1.5~8.0μg/25ml和4.0~15μg/25ml,相互允许量Mo:W=2:1~1:10,该法用于合成水样及标准钢样中的Mo和W的同时测定,结果满意。 相似文献
994.
Abdelouahad El-Himri 《Journal of solid state chemistry》2004,177(9):3219-3223
The molybdenum bimetallic and trimetallic nitrides Pt2Mo3N and PdPtMo3N have been synthesized by ammonolysis of the stoichiometric amorphous precursor, obtained by freeze drying of aqueous solutions of the appropriate metal salts. These compounds have been characterized by elemental analysis, energy-dispersive analysis of X-rays, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetry analysis under an oxygen atmosphere. Pt2Mo3N and PdPtMo3N crystallize in the cubic space group P4132 (213), with lattice parameters of a=6.83586(4) and 6.82542(3) Å, respectively, and form with the unusual filled β-manganese structure. These compounds are stable under air up to 580 K, the oxidation being complete at 910 K. 相似文献
995.
本文研究了罗丹明B与硫氰酸钼形成红色络合物的问题,提出了分光光度法直接测定天然水中微量钼的新方法,方法灵敏(_600~ε=1.88×10~5)干扰少,相对标准偏差小于7%。检出限为2ppb。 相似文献
996.
Violaine Coué 《Journal of solid state chemistry》2006,179(12):3615-3627
Two new organic-inorganic hybrid compounds of molybdenum(VI) (HDBU)3(NH4)[β-Mo8O26]·H2O 1 and (HDBU)4[δ-Mo8O26] 2 have been synthesized and characterized by elemental analyses, FT-IR and UV-vis spectroscopies, and single-crystal X-ray diffraction (at 293 and 100 K, respectively). Compound 1 is obtained at room temperature by adding 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on aqueous molybdate solution at pH=5.7. Compound 2 is obtained hydrothermally from 1 (110 °C, 24 h, autogenous pressure). Compound 1 crystallizes in the triclinic crystal system, space group , with a=11.2492(9), b=14.1907(10), c=16.7498(10) Å, α=80.993(4), β=72.272(6), γ=71.696(7)°, V=2412.5(3) Å3 at T=20 °C and Z=2. The refinement of the structure leads to a residual factor R=0.0697 for 10234 independent observed reflections [I/σ(I)?2] and 623 parameters. Compound 2 crystallizes in the triclinic crystal system, space group , with a=11.3158(9), b=11.3773(8), c=13.2884(17) Å, α=92.110(8), β=112.127(9), γ=117.581(7)°, V=1357.4(3) Å3 at T=−173 °C and Z=2. The refinement of the structure leads to a residual factor R=0.0226 for 11812 independent observed reflections [I/σ(I)?2] and 354 parameters. The structure of 1 consists of β-[Mo8O26]4− anions with HDBU+ and NH4+ cations connected to the mineral parts by hydrogen bonds and the structure of 2 contains δ-[Mo8O26]4− anions with HDBU+ counter-cations. Both the thermal and chemical isomerizations of the two [Mo8O26]4− isomers are highlighted and discussed. Photochromic behaviors of compounds 1 and 2 are also reported. 相似文献
997.
A naked-eye detection method for a trace amount of arsenic in aqueous samples has been newly developed. The proposed method is based on the formation of a hetero poly acid in a chelating resin phase. Molybdenum loaded on a chelating resin having β-hydroxypropyl-di(β-hydroxyethyl) amino moiety reacts with arsenic(V) to form the hetero poly acid, which makes the resin beads greenish blue in the presence of a reducing agent under acidic conditions. It was also found that the intensity of the color of the resin depends on the concentration of arsenic(V) in the sample solutions. Since the development of the color occurs in 20 min by heating of the mixture at 40 °C, this system can provide a simple, rapid and low-cost detection method of a trace amount of arsenic(V) in an aqueous media. The detection limit of this method is 1 × 10−6 mol dm−3. A longer preconcentration time with the same resin gave the higher sensitivity of 1 × 10−7 mol dm−3 that is comparable with that of the instrumental analysis. The present method comprises both the concentration and detection step with the same solid material, and hence it gives higher sensitivity and easier handling than the ordinary colorimetric methods using a liquid medium. 相似文献
998.
Chi-Shian Chen 《Journal of organometallic chemistry》2011,696(7):1474-400
Reaction of Mo(CO)3(NCMe)3 and PPh2(o-C6H4)C(O)H (abbreviated as PCHO) at room temperature affords Mo(CO)2(η3-PCHO)2 (1), while compound 1 and the phosphine-imine complex Mo(CO)4(η2-PPh2(o-C6H4)CHNMe) (2) are obtained by using Mo(CO)3(η3-(MeNCH2)3) as the reactant. Thermal reaction of 1 with C60 products Mo(CO)2(η4-(PPh2(o-C6H4)CH)2)(η2-C60) (3) in low yield, apparently through coupling of the formyl moieties. The structures of 1 and 3 have been determined by an X-ray diffraction study. The two aldehyde groups of 1 and C60 ligand of 3 are coordinated to the molybdenum atom in a π-fashion. 相似文献
999.
Nigel T. Lucas Ian R. Whittall Mark G. Humphrey David C.R. Hockless M.P. Seneka Perera Michael L. Williams 《Journal of organometallic chemistry》1997,540(1-2):147-154
Reactions of CpMoIr3(μ-CO)3(CO)8 (1) with stoichiometric amounts of phosphines afford the substitution products CpMoIr3(μ-CO)3(CO)8−x (L)x (L = PPh3, x = 1 (2), 2 (3); L = PMe3, x = 1 (4), 2 (5), 3 (6)) in fair to good yields (23–54%); the yields of both 3 and 6 are increased on reacting 1 with excess phosphine. Products 2–5 are fluxional in solution, with the interconverting isomers resolvable at low temperatures. A structural study of one isomer of 2 reveals that the three edges of an MoIr2 face of the tetrahedral core are spanned by bridging carbonyls, and that the iridium-bound triphenyiphosphine ligates radially and the molybdenum-bound cyclopentadienyl coordinates axially with respect to this Molr2 face. Information from this crystal structure, 31P NMR data (both solution and solid-state), and results with analogous tungsten—triiridium and tetrairidium clusters have been employed to suggest coordination geometries for the isomeric derivatives. 相似文献
1000.
LU Shao-Fang HUANG Jian-Quan HUANG Xiao-Ying WU Qiang-JinState Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian China 《中国化学》1997,15(4):296-303
A new cluster compound {[Mo3(μ3-O)(μ-S)3(dtp)3(py)3][CdI(dtp)2]} (dtp=S2P(O-was obtained from the reaction of (Mo3OS3(dtp)4(H2O)] with a CdI2-Bu4NI mixture.The molecular structure is composed of a cluster cation [Mo3OS3(dtp)3(py)3]+ and the complex anion [CdI(dtp)2]-Crystal data:Triclinic,space group P1 with cell parameters a=1.4672(7),b=1.5356(5),c=1.6806(5) nm,α=74.59(3),β=67.89(4),7=78.86(3)°,V=3.364(2) nm3,and Z=2,least-squares refinement of 8941 reflections gives a final agreement factor of R=0.052,Rw=0.065. 相似文献