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71.
The dehydration of molybdic acid, MoO3---H2O, was studied by thermal analysis, X-ray diffractometry and FTIR spectroscopy. The results show that an intermediate phase, MoO3-2/3H2O is formed at 216 °C and the monoclinic form of MoO3 is grown above 350 °C. The mechanism of dehydration and structural rearrangement were confirmed by the features of the infrared spectra showing formation of corner-shared MoO6 octahedra. 相似文献
72.
Emma Thorn-Cs nyi J rg Ulrich Zilles 《Journal of molecular catalysis. A, Chemical》2002,190(1-2):85-100
The structure/property relationship of Schrock-type alkylidene complexes with tungsten and molybdenum as central atoms was investigated. Terminal and, E and Z internal olefins as well as double bond substituted and unsubstituted unsaturated polymers served as metathesis substrates. According to the results obtained, it is possible to choose the optimal catalyst depending on the metathesis substrate and temperature, the central atom plays a decisive role. Examples concerning equilibrium polymerization demonstrate the practical utilization. 相似文献
73.
火焰原子吸收分析中表面活性剂的增感和抑制干扰作用的机理研究 总被引:9,自引:0,他引:9
证实和补充了文献[1]建立的FAAS分析中表面活性剂的增感机理模型,并对FAAS分析中表面活性剂抑制共存元素干扰的作用和机理作了探讨。表面活性剂能抑制共存元素干扰的主要原因是其胶团能和被测元素的离子或干扰离子形成胶团化物;表面活性剂在火焰中中的不完全燃烧使火焰气体还原性增强,温度升高也是其抑制干扰的因素之一。 相似文献
74.
Resasco D.E. Alvarez W.E. Pompeo F. Balzano L. Herrera J.E. Kitiyanan B. Borgna A. 《Journal of nanoparticle research》2002,4(1-2):131-136
Existing single-walled carbon nanotube synthesis methods are not easily scalable, operate under severe conditions, and involve high capital and operating costs. The current cost of SWNT is exceedingly high. A catalytic method of synthesis has been developed that has shown potential advantages over the existing methods. This method is based on a catalyst formulation that inhibits the formation of undesired forms of carbon; it can be scaled-up and may result in lower production costs. 相似文献
75.
二溴羟基苯基荧光酮荧光熄灭法测定微量钼 总被引:9,自引:0,他引:9
本文用荧光熄灭法研究了十溴羟基苯基荧光酮(DBH-PF)-溴化十六烷基三甲铵(CTMAB)-Mo(Ⅵ)体系的测定方法及条件。在0.002~0.008mol/L的H_3PO_4介质中,在CTMAB存在下,钼(Ⅵ)与试剂形成1:2的桔红色络合物,其最大激发波长为470nm和502nm,最大发射波长为520nm。钼在0.03~0.50μg/25ml范围内具有线性关系,检出限为0.03μg/25ml。本法灵敏度高,选择性好,用于检测合金钢中的微量钼,结果满意。 相似文献
76.
本文报导了傅里哀变换红外发射光谱法研究多相氧化物催化剂的实验装置的建立及实验条件的考察。设计加工了一个温度范围宽,可在各种气氛和真空条件下原位研究氧化物催化剂的红外发射池。以MoO_3为例,考察了样品厚度,测试温度对发射光谱的影响。当样品量小于1mm·cm~(-2)时,随样品量增加,谱峰强度线性增加,但峰形不发生变化。当样品量高于1mg.cm~(-2)时,随样品量增加,谱图严重畸变。随样品温度升高,谱峰强度近似线性增加。并用该方法研究了MoO_3在还原和再氧化过程中表面氧物种的变化。结果表明桥式MO?O?Mo物种比端基Mo=O物种较易还原,再氧化时,Mo=O物种比Mo?O?Mo物种优先形成。 相似文献
77.
《Analytical letters》2012,45(7):1807-1817
Abstract A new selective and sensitive method for extraction of yellow Mo (VI)-caffeic acid complex with a liquid ion exchanger, Aliquat 336 from 4.0 pH, and spectrophotometric determination of molybdenum in trace amounts is described. the molar absorptivity of the complex is 1.1 × 105 1 mol?1 cm?1 at 340 nm and the colour system obeys Beer's law in the range 0.04–0.99 ppm of Mo(VI). the molybdenum is also determined with AAS and the method is applied for its determination in steel and environmental samples. 相似文献
78.
The reaction of Ph3SnCl, (R4N)2[Mo6O19] and (R4N)OH in a molar ratio of 6:1:10 leads to the formation of (R4N)[(Ph3Sn)MoO4] (R = nPr ( 1 ), nBu ( 2 )). Compounds 1· CH3CN and 2 have been charactarized by IR spectroscopy and single crystal X‐ray diffraction. 1· CH3CN forms orthorhombic crystals, space group P212121 with a = 1339.9(2), b = 1508.9(2), c = 1733.2(3) pm. 2 crystallizes in the monoclinic space group P21 with a = 1342.6(2), b = 2280.3(4), c = 1344.0(2) pm, β = 118.34(1). Both compounds 1 and 2 consist of isolated R4N+ cations and polymeric $\rm^{1}_{\infty}$ [(Ph3Sn)MoO4]– chains with an alternating arrangement of Ph3Sn+ and MoO42– groups. Treatment of (Ph3Sn)2MoO4 with bis(ethylenediamine)copper(II) succinate yields [Cu(en)2(Ph3Sn)2(MoO4)2] ( 3 ). The zinc derivative [Zn(en)2(Ph3Sn)2(MoO4)2] ( 4 ) is obtained similarly by reaction of (Ph3Sn)2MoO4 with bis(ethylenediamine)zinc(II) formiate. Compounds 3· 2DMF · EtOH and 4· 2DMF · EtOH crystallize in the monoclinic space group P21/n with a = 1998.0(2), b = 1313.3(1), c = 2181.6(2) pm, β = 90.97(1)° for 3 and a = 2015.4(1), b = 1316.7(1), c = 2157.0(1) pm, β = 90.40(1)° for 4 . Like in the cases of 1 and 2, polymeric $\rm^{1}_{\infty}$ [(Ph3Sn)MoO4]– chains are observed. The [M(en)2]2+ units (M = Cu, Zn) act as linkers between the $\rm^{1}_{\infty}$ [(Ph3Sn)MoO4]– chains to give 2D layer structures with (6, 3) net topology. 相似文献
79.
《Journal of Coordination Chemistry》2012,65(16):1375-1381
Interaction of bis-(salicylaldehyde)ethylenediimine, salenH2, with M(CO)6 (M = Cr, Mo) in air gave M(O)(salen) complexes. Magnetic studies show that the metal exists in the +4 oxidation state. Cr(CO)6 reacted with salenH2 under reduced pressure to yield the dicarbonyl derivative Cr(CO)2(salenH2). Reactions of M(CO)6 with salenH2 in the presence of a secondary ligand L (L = H2O, pyridine) resulted in the formation of the square pyramidal complex M(L)(salenH2). UV-Vis spectra of the complexes exhibited visible bands due to metal-to-ligand charge transfer. Structures for the complexes are proposed on the basis of spectroscopic studies. 相似文献
80.
《Journal of Coordination Chemistry》2012,65(4):289-300
Abstract In a template synthesis from ethanolic solution of MoOCl3, 2,6-diacetylpyridine (dap), and semioxamazide (sox), in the molar ratio 1:1:2, a dimeric molybdenum(V) complex [Mo2O2(H2dapsox)2]Cl6 · 4H2O (where H2dapsox = 2′,2″′-(2,6-pyridinediyldiethylidenedioxa-mohydrazide) was obtained. In a similar reaction, starting from La(NO3)3 · 6H2O, the complex [La(H2dapsox)(NO3) x ](NO3)3-x · 1/2EtOH (x = 1,2), having coordination number 9, was obtained. In the latter complex two NO3 Groups were bidentately coordinated in the solid state, but only one in the solution. Besides [Mo2O2(TPP)2] (TPP = tetraphenylporphyrin), the molybdenum(V) complex [Mo2O2 (H2dapsox)2]Cl6 · 4H2O is the only other known example of a dimeric μ-oxodimolybdenum(V) species that is paramagnetic (μ = 0.95 BM). One of the Mo atoms has pentagonal bipyramidal coordination, and the other pentagonal pyramidal coordination. In aqueous solution a rare example of a pentagonal pyramidal ion [MoO(dapsox)]+ is presumably present. Solution EPR spectra (at 77K) cannot be related to either of the two known types of Mo(V) species based on the extent of g anisotropy. The substances also were characterized by IR and electronic spectroscopy, and by thermal analysis. 相似文献