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1.
混凝沉淀法处理工业含氟废水的工艺研究   总被引:4,自引:0,他引:4  
周霖  张彰  方瑜 《化学研究》2010,21(5):54-57,62
以半导体工业中的含氟废水为研究对象,采用混凝沉淀法对去除废水中氟离子进行了系统的工艺研究.以Ca(OH)2为沉淀剂,分别用聚合氯化铁(PFC)和聚合氯化铝(PAC)为混凝剂,并加入聚丙烯酰胺(PAM)助凝剂的方法,对药剂投加量、混凝剂种类、体系pH值、沉降时间等因素进行了实验探索.结果显示,PFC比PAC混凝效果好.当Ca(OH)2添加量为理论值的2.5倍,PFC用量为15mg/L,助凝剂PAM用量为4mg/L,体系的pH值在6~7时,其除氟效果最佳,此时废水中残留氟离子浓度可降低至5.5mg/L,远远低于国家规定的排放标准(10mg/L).  相似文献   

2.
聚合氯化铁的制备及其絮凝效果   总被引:1,自引:0,他引:1  
以赤铁矿和工业盐酸为原料,采用盐酸酸浸和加碱聚合等方法制取聚合氯化铁絮凝剂(PFC),将其用来处理造纸废水,并与市售聚合氯化铁和碱式氯化铝絮凝剂进行比较.结果表明,在碱化度为2∶1、聚合温度为40℃、陈化时间为24h时,自制聚合氯化铁絮凝剂对造纸废水具有较好的处理效果;投加量为1.4mL/L时,造纸废水的浊度降低了99%,化学需氧量(COD)降低了69.55%,优于市售絮凝剂对造纸废水的处理效果;且三种絮凝剂用量相同时,自制的聚合氯化铁絮凝剂形成絮体的速率和沉降速率都较快.  相似文献   

3.
近年来, 太阳能驱动的光电化学水分解作为一种高效、环保、可持续的技术, 已经引起了广泛的关注. 为了更好地使用光电化学技术将太阳能转化为化学能, 至关重要的是提高光电极材料的光吸收和光转化效率. BiVO4禁带宽度(Eg=2.4-2.5 eV)小, 具有很好的可见光响应能力, 因此BiVO4光电极材料引起了广泛关注. 但是, 当单独BiVO4作为光电阳极材料时, 电子-空穴对分离弱、载流子传输慢, 从而使BiVO4不能很好地在光电化学水分解中发挥作用. 为了缓解或解决此类限制性因素, 本课题组通过水热法合成了NiFe双氢纳米粒子, 并将其负载于BiVO4电极表面, 光电催化分解水实验表明其产氢效率得到大幅度提高. 同时制备了Ni(OH)2/BiVO4和Fe(OH)2/BiVO4电极并用于研究NiFe/BiVO4电极的反应机理. 在上文基础上, 本文采用电子扫描电镜(SEM)、高分辨投射电镜(HRTEM)、X射线衍射(XRD)、紫外可见漫反射(UV-Vis DRS)等表征手段和线性扫描伏安法(LSV)和电流时间(I-t)等对其光电化学活性进行了测试, 研究了NiFe/BiVO4电极在发生水氧化时的反应机理. SEM结果表明, Ni(OH)2是以纳米片组成的纳米球负载于多孔BiVO4表面; 而当Fe(OH)2负载于BiVO4表面时, BiVO4的纳米尺寸减小; NiFe-LDH纳米粒子负载于BiVO4表面时, 可以明显看见BiVO4纳米颗粒表面包裹着一层更小的纳米粒子.这证明了Ni(OH)2, Fe(OH)2和NiFe-LDH纳米粒子均成功负载于BiVO4表面. 这也得到HRTEM结果的确认. UV-Vis DRS结果表明NiFe-LDH纳米粒子能有效拓宽BiVO4的吸收边, 从而增加对可见光的吸收, 增加了对光的利用率. LSV测试结果表明, 暗反应条件下Ni(OH)2/BiVO4比NiFe/BiVO4和Fe(OH)2/BiVO4电极的起始电位更低, 说明Ni(OH)2有更好的传输电子性能; 而在光照条件下, 在同一电位时NiFe/BiVO4比Ni(OH)2/BiVO4和Fe(OH)2/BiVO4电极的光电流值更高. 值得注意的是, 此时Ni(OH)2/BiVO4比Fe(OH)2/BiVO4电极的光电流值低, 这又说明Fe(OH)2比Ni(OH)2对光更敏感. 因此当NiFe-LDH纳米粒子负载于BiVO4表面时, 不仅提高了BiVO4光电极的光吸收效率, 而且加速了载流子的传输从而抑制了光生电子-空穴的复合, 使反应过程中的量子效率得到提高.  相似文献   

4.
近年来,太阳能驱动的光电化学水分解作为一种高效、环保、可持续的技术,已经引起了广泛的关注.为了更好地使用光电化学技术将太阳能转化为化学能,至关重要的是提高光电极材料的光吸收和光转化效率.BiVO_4禁带宽度(Eg=2.4–2.5 eV)小,具有很好的可见光响应能力,因此BiVO_4光电极材料引起了广泛关注.但是,当单独BiVO_4作为光电阳极材料时,电子-空穴对分离弱、载流子传输慢,从而使BiVO_4不能很好地在光电化学水分解中发挥作用.为了缓解或解决此类限制性因素,本课题组通过水热法合成了NiFe双氢纳米粒子,并将其负载于BiVO_4电极表面,光电催化分解水实验表明其产氢效率得到大幅度提高.同时制备了Ni(OH)_2/BiVO_4和Fe(OH)2/BiVO_4电极并用于研究NiFe/BiVO_4电极的反应机理.在上文基础上,本文采用电子扫描电镜(SEM)、高分辨投射电镜(HRTEM)、X射线衍射(XRD)、紫外可见漫反射(UV-Vis DRS)等表征手段和线性扫描伏安法(LSV)和电流时间(I-t)等对其光电化学活性进行了测试,研究了NiFe/BiVO_4电极在发生水氧化时的反应机理.SEM结果表明,Ni(OH)_2是以纳米片组成的纳米球负载于多孔BiVO_4表面;而当Fe(OH)2负载于BiVO_4表面时,BiVO_4的纳米尺寸减小;NiFe-LDH纳米粒子负载于BiVO_4表面时,可以明显看见BiVO_4纳米颗粒表面包裹着一层更小的纳米粒子.这证明了Ni(OH)_2,Fe(OH)2和NiFe-LDH纳米粒子均成功负载于BiVO_4表面.这也得到HRTEM结果的确认.UV-Vis DRS结果表明NiFe-LDH纳米粒子能有效拓宽BiVO_4的吸收边,从而增加对可见光的吸收,增加了对光的利用率.LSV测试结果表明,暗反应条件下Ni(OH)_2/BiVO_4比NiFe/BiVO_4和Fe(OH)2/BiVO_4电极的起始电位更低,说明Ni(OH)_2有更好的传输电子性能;而在光照条件下,在同一电位时NiFe/BiVO_4比Ni(OH)_2/BiVO_4和Fe(OH)2/BiVO_4电极的光电流值更高.值得注意的是,此时Ni(OH)_2/BiVO_4比Fe(OH)2/BiVO_4电极的光电流值低,这又说明Fe(OH)2比Ni(OH)_2对光更敏感.因此当NiFe-LDH纳米粒子负载于BiVO_4表面时,不仅提高了BiVO_4光电极的光吸收效率,而且加速了载流子的传输从而抑制了光生电子-空穴的复合,使反应过程中的量子效率得到提高  相似文献   

5.
邻菲啰啉光度法常用于Fe(Ⅱ)测定,但受到试样中Fe(Ⅲ)对测定的影响,因此不能直接用于生物浸出样品中Fe(Ⅱ)和Fe(Ⅲ)的同时测定.为此,基于Fe(Ⅱ)邻菲啰啉特征吸收曲线以及混合铁中Fe(Ⅲ)对Fe(Ⅱ)测定的线性影响关系,建立了基于Fe(Ⅱ)和全铁同时测定Fe(Ⅱ)和Fe(Ⅲ)的计算光度法,并研究了生物浸出样品中典型金属离子(Cu2+、Ni2+、Cd2+、Co2+)以及试样溶解与储放对测定的影响.方法可准确地测定含铁次生矿物和生物浸出液中铁价态组成,应用于生物浸出矿渣、细胞表面中常量或微量的Fe(Ⅱ)和Fe(Ⅲ)组成分析,具有简便快速的特点.  相似文献   

6.
新型吡啶双亚胺铁催化乙烯聚合反应   总被引:1,自引:0,他引:1  
李彦国  刘三荣  刘靖宇 《应用化学》2009,26(9):1100-1103
合成与表征了一种新型吡啶双亚胺铁烯烃聚合催化剂2,6-二[1-(4-羟基-2,6-二甲基苯胺)乙基]吡啶氯化铁(1a)。结果表明,在亚胺环的对位引入羟基,可同时提高催化剂的活性和聚合物的分子量。在改性甲基铝氧烷(MMAO)的活化下,该催化剂引发乙烯聚合的活性(以单位时间(h)mol Fe引发乙烯聚合的PE质量(g)来表征)可达到6.78×106 g/(mol•h),明显高于已知催化剂2,6-二[1-(2,6-二甲基苯胺)乙基]吡啶氯化铁(1b),且能得到更高分子量的聚乙烯。  相似文献   

7.
季晓亮  王锦化 《化学教育》2009,30(11):65-66,68
为了从一种全新的视角和手段探讨新课程中锌与氯化铁溶液反应到底生成什么产物的问题,通过微波实验方法和正交实验设计,将影响该反应的各种因素和水平进行了科学、全面、均衡地安排,根据定量实验数据,得出了:7Zn+6FeCl3+6H2O=2Fe(OH)3+2Fe+7ZnCl2+2FeCl2+3H2↑的实验结论.  相似文献   

8.
刘荣森  赵文善 《分析试验室》2014,(11):1305-1307
建立了用K3[Fe(CN)6]—Fe(III)体系分光光度法测定头孢氨苄的方法。在0.25 mol/L Na OH溶液中,头孢氨苄在80℃降解为巯基化合物。巯基化合物中的巯基能将Fe(III)还原为Fe(II),Fe(II)与K3[Fe(CN)6]生成可溶性的普鲁士蓝,通过测定生成的普鲁士蓝的吸光度,间接测定了头孢氨苄的含量。头孢氨苄质量浓度在0.08~8.10μg/m L范围内呈现良好的线性关系,线性回归方程A=0.0203+0.2408ρ(μg/m L),相关系数R=0.9993.摩尔吸光系数ε=8.80×104L/(mol·cm)。相对标准偏差RSD为1.1%(n=11),检出限为10 ng/m L。方法可用于头孢氨苄胶囊含量的测定。  相似文献   

9.
本文从共聚物结晶的两种模型出发,总结了共聚物的熔点、熔化热与组成的关系,提出了从熔化曲线得到组成分布的方法。然后以全氟乙丙烯共聚物作为研究对象,用实验方法对上述关系进行了验证,再用来测定乳液及悬浮聚合试样的组成分布,得到了初步结果。发现乳液聚合试样的组成分布要比悬浮聚合为窄;对于平均组成相近的试样,组成分布宽的,其应力开裂性能较差。  相似文献   

10.
丁二烯聚合铁系催化剂的磁性分析   总被引:1,自引:1,他引:1  
丁二烯聚合铁系催化剂FeCl_3-Phen-Al(i-Bu)_3的磁化率和紫外可见光谱测定结果表明,三氯化铁与乙酸乙酯(EA)形成高自旋络合物FeCl_3·(EA)_2;FeCl_3·(EA)_2-Al(i-Bu)_3体系显强铁磁性;Phen有稳定Fe(Ⅱ)、显著降低铁磁性的作用。  相似文献   

11.
Pribil R  Horácek J 《Talanta》1969,16(6):750-752
Potentiometric determination of iron with DTPA at pH 1.6 (platinum and calomel electrodes) permits determination of iron in the presence of aluminium up to an Al:Fe ratio of 70. Aluminium is determined indirectly by addition of excess of DCTA, adjustment to pH 5, and back-titration with iron(III) chloride.  相似文献   

12.
Hydroxyl radicals were generated in the Fenton reaction at pH 4 (Fe(2+) + H(2)O(2) --> Fe(3+) + .OH + OH-, k approximately equal to 60 L mol(-1) s(-1)) and by pulse radiolysis (for the determination of kinetic data). They react rapidly with 1,3-dimethyluracil, 1,3-DMU (k = 6 x 10(9) L mol(-1) s(-1)). With H(2)O(2) in excess and in the absence of O(2), 1,3-DMU consumption is 3.3 mol per mol Fe(2+). 1,3-DMUglycol is the major product (2.95 mol per mol Fe(2+)). Dimers, prominent products of .OH-induced reactions in the absence of Fe(2+)/Fe(3+) (Al-Sheikhly, M.; von Sonntag, C. Z. Naturforsch. 1983, 31b, 1622) are not formed. Addition of .OH to the C(5)-C(6) double bond of 1,3-DMU yields reducing C(6)-yl 1 and oxidizing C(5)-yl radicals 2 in a 4:1 ratio. The yield of reducing radicals was determined with tetranitromethane by following the buildup of nitroform anion. Reaction of 1 with Fe(3+) that builds up during the reaction or with H(2)O(2) gives rise to a short-chain reaction that is terminated by the reaction of Fe(2+) with 2, which re-forms 1,3-DMU. In the presence of O(2), 1.1 mol of 1,3-DMU and 0.6 mol of O(2) are consumed per mol Fe(2+) while 0.16 mol of 1,3-DMU-glycol and 0.17 mol of organic hydroperoxides (besides further unidentified products) are formed. In the presence of O(2), 1 and 2 are rapidly converted into the corresponding peroxyl radicals (k = 9.1 x 10(8) L mol(-1) s(-1)). Their bimolecular decay (2k = 1.1 x 10(9) L mol(-1) s(-1)) yields approximately 22% HO(2)./O(2).(-) in the course of fragmentation reactions involving the C(5)-C(6) bond. Reduction of Fe(3+) by O(2).(-) leads to an increase in .OH production that is partially offset by a consumption of Fe(2+) in its reaction with the peroxyl radicals (formation of organic hydroperoxides, k approximately 3 x 10(5) L mol(-1) s(-1); value derived by computer simulation).  相似文献   

13.
The experimental and theoretical thermochemistry of the gaseous neutral and ionic iron oxides and hydroxides FeO, FeOH, FeO(2), OFeOH, and Fe(OH)(2) and of the related cationic water complexes Fe(H(2)O)(+), (H(2)O)FeOH(+), and Fe(H(2)O)(2)(+) is analyzed comprehensively. A combination of data for the neutral species with those of the gaseous ions in conjunction with some additional measurements provides a refined and internally consistent compilation of thermochemical data for the neutral and ionic species. In terms of heats of formation at 0 K, the best estimates for the gaseous, mononuclear FeO(m)H(n)(-/0/+/2+) species with m = 1, 2 and n = 0-4 are Delta(f)H(FeO(-)) = (108 +/- 6) kJ/mol, Delta(f)H(FeO) = (252 +/- 6) kJ/mol, Delta(f)H(FeO(+)) = (1088 +/- 6) kJ/mol, Delta(f)H(FeOH) = (129 +/- 15) kJ/mol, Delta(f)H(FeOH(+)) = (870 +/- 15) kJ/mol, Delta(f)H(FeO(2)(-)) = (-161 +/- 13) kJ/mol, Delta(f)H(FeO(2)) = (67 +/- 12) kJ/mol, Delta(f)H(FeO(2)(+)) = (1062 +/- 25) kJ/mol, Delta(f)H(OFeOH) = (-84 +/- 17) kJ/mol, Delta(f)H(OFeOH(+)) = (852 +/- 23) kJ/mol, Delta(f)H(Fe(OH)(2)(-)) = -431 kJ/mol, Delta(f)H(Fe(OH)(2)) = (-322 +/- 2) kJ/mol, and Delta(f)H(Fe(OH)(2)(+)) = (561 +/- 10) kJ/mol for the iron oxides and hydroxides as well as Delta(f)H(Fe(H(2)O)(+)) = (809 +/- 5) kJ/mol, Delta(f)H((H(2)O)FeOH(+)) = 405 kJ/mol, and Delta(f)H(Fe(H(2)O)(2)(+)) = (406 +/- 6) kJ/mol for the cationic water complexes. In addition, charge-stripping data for several of several-iron-containing cations are re-evaluated due to changes in the calibration scheme which lead to Delta(f)H(FeO(2+)) = (2795 +/- 28) kJ/mol, Delta(f)H(FeOH(2+)) = (2447 +/- 30) kJ/mol, Delta(f)H(Fe(H(2)O)(2+)) = (2129 +/- 29) kJ/mol, Delta(f)H((H(2)O)FeOH(2+)) = 1864 kJ/mol, and Delta(f)H(Fe(H(2)O)(2)(2+)) = (1570 +/- 29) kJ/mol, respectively. The present compilation thus provides an almost complete picture of the redox chemistry of mononuclear iron oxides and hydroxides in the gas phase, which serves as a foundation for further experimental studies and may be used as a benchmark database for theoretical studies.  相似文献   

14.
Complex formation equilibria in l-glutamic acid (H2Glu) and l-serine (HSer) +iron(III) ion systems have been studied by a combination of glass electrode potentiometric and visible spectrophotometric measurements in 0.5 mol dm–3 (Na)NO3 ionic medium at 25°C. In the concentration range 1.0[Fe3+]5.0; 3.0[Glu2–]30.0 mmol dm–3 ([Glu]/[Fe]=3:1 to 30:1) and pH between 1.5 and 4.5, iron(III) and glutamic acid form the Fe(Glu)–2, Fe(Glu)+, Fe(HGlu)2+, Fe(OH)Glu, Fe2(OH)2Glu2+, Fe(OH)Glu22– complexes: and several pure hydrolytic products. Iron(III) and l-serine, beside pure hydrolytic complexes of iron(III), form the Fe(HSer)3+, Fe(Ser)2+, Fe(OH)Ser+, Fe(OH)2- Ser0, Fe(OH)Ser2 and Fe2(OH)2(Ser)2+2 complexes, over a broad concentration range of serine to iron ([Ser]/[Fe]=5:1 to 500:1), from pH 1.5 to 4.0. The stability constants of the complexes are given and their formation mechanism is suggested. The possible structure of the complexes, in solution, is discussed.  相似文献   

15.
研究了硅藻土-TBP反相萃取层析-分光光度法分离和测定微量铁的新方法.以0.30mol/L盐酸做流动相,以负载有磷酸三丁酯(TBP)的硅烷化白色担体为固定相,反相萃取层析法分离微量Fe(Ⅲ)与Co(Ⅲ)、Ge(Ⅳ)、Al(Ⅲ)、Cr(Ⅲ)、Mn(Ⅱ)、Ni(Ⅱ)等.在4.0mol/L盐酸介质中,铁与多种金属离子都被萃取在TBP柱上.用2mol/L盐酸洗脱部分离子,用0.30mol/L盐酸可定量地洗脱铁,然后用0.010mol/L盐酸可将柱上的其它离子洗脱.洗脱液中的铁用分光光度法测定.此方法可将铁与绝大部分干扰离子分离,并用于中草药中微量铁的分离和测定.  相似文献   

16.
Regularities of formation of nanocrystalline iron(III) oxides and oxyhydroxides via oxidation of iron(II) compounds in an alkaline pH range (pH ≥ 12) were studied using pH and E h measurements, chemical analysis, electron microscopy, and X-ray diffraction. When the molar ratio [OH]/[FeII] ∼ 2 (pH ∼ 12–12.5), the oxidation process yields cube-shaped magnetite Fe3O4 particles. An excess of an alkaline agent with an overstoichiometric concentration equal to or higher than 0.5 mol/L (pH ≥ 13.5) induces the formation of anisotropic particles of nanocrystalline goethite α-FeOOH over the entire range of the synthesis parameters studied. Reaction products (Fe3O4 and/or α-FeOOH) are formed immediately as the initial Fe(OH)2 starts oxidizing by the dissolution-oxidation-precipitation mechanism near the surface of Fe(OH)2 precursor particles. Carbonate ions considerably change the structure and shape of newly formed α-FeOOH particles.  相似文献   

17.
《Analytical letters》2012,45(2):481-492
Abstract

A voltammetric method for the determination of iron at detection limit of 4 μg/l is described, using the catalytic current of the reduction of the Fe(III)-triethanolamine (TEA) complex in the presence of bromate ions. the determination was performed at a mercury hanging drop electrode without preconcentration, using the TEA alkaline solution as a supporting electrolyte and the differential pulse technique. A peak current for the Fe(III)-TEA catalytic reduction was observed at a potential of-1.0 V (Ag/AgCl saturated electrode). the influence of TEA, BrO3 and NaOH concentrations on the peak height was studied. It was found that a 100-fold excess of Mn, a 50-fold excess of Cr(VI) and Zn did not interfere in the determination. This method was applied to the determination of iron in water, snow and waste water samples.  相似文献   

18.
Divalent cobalt and iron removal from aqueous solutions by batch ion exchange with a synthetic Na-Y zeolite has been studied under competitive and noncompetitive conditions. The binary Co/Na and Fe/Na ion-exchange equilibrium isotherms, constructed at 291+/-2 K and a total solution positive charge concentration of 0.1 eq dm(-3), exhibited sigmoidal shapes that are attributed to an exchange site heterogeneity. The solution pH and the ratio of sorbate to sorbent are identified for which minimal imbibition of metal hydroxide and maintenance of zeolite structural integrity are ensured. An increase in Fe and Co concentration over the range 0.005-0.05 mol dm(-3) lowered the removal efficiency but the external Fe was preferred to the indigenous sodium over the entire concentration range; there was a switch in preference from Co to Na at [Co] in excess of 0.034 mol dm(-3). Exchange data for Cu(2+)/Na(+) and Ni(2+)/Na(+) binary systems are included for comparative purposes, and ion exchange affinity and Na-Y exchange capacity are discussed in terms of metal ion hydration and ion location. The effect of exchange temperature has been considered where the maximal Fe exchange was temperature independent while Co exchange was promoted with increasing temperature. A Co/Fe/Na-Y ternary exchange isotherm was constructed from 20 pairs of experimental points and is treated quantitatively in terms of ternary and pseudo-binary separation factors. The preference of the zeolite for exchange with iron over cobalt under noncompetitive conditions also extended to solutions containing both metals. Copyright 2000 Academic Press.  相似文献   

19.
采用超声浸渍法制备了Cu、Fe 双活性组元改性的双孔载体(M)催化剂, 采用N2物理吸附、H2程序升温 还原/脱附(H2-TPR/TPD)、X射线衍射(XRD)等表征手段考察了催化剂中Cu-Fe的相互作用, 并在固定床反应器 中评价了Cu/Fe摩尔比的改变对低碳醇合成反应性能的影响. 结果表明: 小孔硅溶胶浸渍在大孔硅凝胶中可形 成具有不同纳米孔径结构的双孔载体, 增加小孔硅溶胶的含量可促使双孔载体中小孔纳米结构尺寸变小. Fe/ Cu摩尔比的增加有利于铜物种在载体表面的分散, 促进了表层CuO和Fe2O3的还原, 加强了双孔载体内孔道 与铜铁氧化物之间的相互作用, 促使了单质铜的分散和铁碳化物的生成. CO加氢反应活性和低碳醇时空收率 随着Fe/Cu 摩尔比的逐渐增加呈现增加的变化趋势. 当Fe/Cu 摩尔比增加到30/20 时, Cu-Fe 基双孔载体催化 剂的CO转化率增加到46%, 低碳醇的时空收率增加到0.21 g·mL-1·h-1, C2+OH/CH3OH质量比达到1.96.  相似文献   

20.
Non-heme manganese and iron complexes with terminal hydroxo or oxo ligands are proposed to mediate the transfer of hydrogen atoms in metalloproteins. To investigate this process in synthetic systems, the monomeric complexes [M(III/II)H(3)1(OH)](-/2-) and [M(III)H(3)1(O)](2-) have been prepared, where M(III/II) = Mn and Fe and [H(3)1](3-) is the tripodal ligand, tris[(N'-tert-butylureaylato)-N-ethyl)]aminato. These complexes have similar primary and secondary coordination spheres, which are enforced by [H(3)1](3-). The homolytic bond dissociation energies (BDEs(O-H)) for the M(III/II)-OH complexes were determined, using experimentally obtained values for the pK(a)(M-OH) and E(1/2) measured in DMSO. This thermodynamic analysis gave BDEs(O-H) of 77(4) kcal/mol for [Mn(II)H(3)1(O-H)](2-) and 66(4) kcal/mol for [Fe(II)H(3)1(O-H)](2-). For the M(III)-OH complexes, [Mn(III)H(3)1(OH)]- and [Fe(III)H(3)1(OH)]-, BDEs(O-H) of 110(4) and 115(4) kcal/mol were obtained. These BDEs(O-H) were verified with reactivity studies with substrates having known X-H bond energies (X = C, N, O). For instance, [Fe(II)H(3)1(OH)](2-) reacts with a TEMPO radical to afford [Fe(III)H(3)1(O)](2-) and TEMPO-H in isolated yields of 60 and 75%, respectively. Consistent with the BDE(O-H) values for [Mn(II)H(3)1(OH)](2-), TEMPO does not react with this complex, yet TEMPO-H (BDE(O-H) = 70 kcal/mol) reacts with [Mn(III)H(3)1(O)](2-), forming TEMPO and [Mn(II)H(3)1(OH)](2-). [Mn(III)H(3)1(O)](2-) and [Fe(III)H(3)1(O)](2-) react with other organic substrates containing C-H bonds less than 80 kcal/mol, including 9,10-dihydroanthracene and 1,4-cyclohexadiene to produce [M(II)H(3)1(OH)](2-) and the appropriate dehydrogenated product in yields of greater than 80%. Treating [Mn(III)H(3)1(O)](2-) and [Fe(III)H(3)1(O)](2-) with phenolic compounds does not yield the product expected from hydrogen atom transfer but rather the protonated complexes, [Mn(III)H(3)1(OH)]- and [Fe(III)H(3)1(OH)]-, which is ascribed to the highly basic nature of the terminal oxo group.  相似文献   

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