Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)₂Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC₆H₄)₃ and P(4-MeC₆H₄)₃. The products of the reaction, [CpFe(CO)(COMe)P(4-FC₆H₄)₃] (2a) and [CpFe(CO)(COMe)P(4-MeC₆H₄)₃] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) Å in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) Å in 2b, respectively.The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC₆H₄)₃ was observed when the solvent was changed from CH₂Cl₂ to MeCN. The kinetic data showed that P(4-MeC₆H₄)₃ reacts faster than P(4-FC₆H₄)₃.     

Flow injection on-line ultrasound-assisted extraction of iron in meat samples coupled to a flame atomic absorption spectrometric system

Iron was extracted on-line from solid meat samples by a simple and rapid continuous ultrasound-assisted extraction system (CUES). The CUES is connected to a flow injection manifold, which allows the on-line flame atomic absorption spectrometric determination of iron. A Plakett–Burman design was used for the optimisation of the CUES. The method achieved a total sampling frequency of 11 samples per hour with a relative standard deviation for the complete procedure of 0.4%. The detection limit was 0.6 g g^–1 (dry mass) for a sample amount of 30 mg. Accurate results were obtained by measuring the certified reference materials BCR-186 (pig kidney) and BCR-184 (bovine muscle). The analytical procedure was applied to different real meat samples with satisfactory results.     

4,5-二溴苯基荧光酮-溴化十六烷基三甲铵荧光熄灭法测定微量铁

本文利用DBPF为荧光试剂,在大量CTMAB存在下,用荧光熄灭法测定微量铁,λ_(ex)为362nm,λ_(em)560nm。线性范围为0.002～0.12μg/mL。三元络合物中,Fe:DBPF=1:3。     

Eastman-Kodak AQ膜修饰电极阴极溶出伏安法测定痕量铁

本文用热处理法成功地制备了性能稳定的Eastman-Kodak AQ/GC修饰电极,对Fe~(3+)/Fe~(2+)及其络合阳离子在该电极上的行为进行了研究。表明AQ膜对Fe~(3+)和Fe~(2+)具有相近的交换能力,可用于Fe~(3+)或Fe~(2+)及其总量的阴极溶出伏安法测定。线性范围分别为2.0×10~(-7)～2.2×10~(-5)mol/L(Fe~(3+))和5.0×10~(-7)～2.0×10~(-5)mol/L(Fe~(2+)),检出限为1.0×10~(-7)mol/L(Fe~(3+))。文中对电极反应和再生进行了探讨。     

一阶导数停流法测定药物和饮用水中的铁

本文利用Ｆｅ＾３＋离子催化Ｈ２Ｏ２氧化四甲基对苯二胺的反应，将采用停流技术获得的动力学曲线转换成一阶导数曲线，根据导数峰高值与Ｆｅ＾３＋离子浓度的线性关系测定药物和自来水中的含量，本方法的线性范围为４．０－４０．０ｎｇＦｅ＾３＋／ｍｌ，相对标准偏差小于２．５％，标准加入回收率在９８．７％－１０１％之间，检测限为１．９２ｎｇＦｅ＾３＋／ｍｌ。对照实验结果表明，导数动力学法比一般非导数动力学法具有线关     

金属离子对中位─四（4─N甲氧羰甲基吡啶）卟啉表面增强拉曼光谱的影响

研究了金属离子对吸附在银胶表面的中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉表面增强拉曼光谱的影响。结果表明，中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉可发生金属离子取代反应。金属离子嵌入卟啉大环，吸附在银胶表面的中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉转变为金属配合物。给出了各种金属配合物主要拉曼峰的经验式归属。金属离子的半径，ｄ电子对卟啉环的排斥作用，金属卟啉骨架模式频率随孔穴大小，大环的平面性和π－π相互作用而相应变化的特性，都可用来解释不同金属离子配合物的结构灵敏特征峰为何存在着差异。     

Chemical species produced in the reaction between ethanedial (glyoxal) and 5-amino-1,10-phenanthroline and their iron(II) complexes: preparation and some spectrometric studies

Chemical species obtained by reaction of 5-amino-1, 10-phenanthroline with ethanedial (glyoxal) are reported with regard to their preparation, chemical composition and spectrometric characterization (UV-visible, infrared and liquid secondary ion mass spectrometry). Products of the reaction are postulated to be a mixture of species with molecular weights of 339, 371,480 and 524 u. Chemical reactions leading to these products and possible structural formulas for each of these species are presented. The iron complexes of these ligands, because of their extremely low solubility in most solvents, find application as redox mediators when incorporated in carbon paste electrodes, particularly for sensing in continuous-flow systems.     

Simple and versatile operational fractionation of Fe and Zn in dietary products by solid phase extraction on ion exchange resins

A simple and versatile protocol, based on use of solid phase extraction on strong ion exchangers and off-line detection by flame atomic absorption spectrometry, was devised to fractionate iron and zinc in common dietary food and beverages products, i.e., bee honeys, fruit juices and tea infusions. In the procedure proposed, cation exchanger Dowex 50Wx4 and anion exchanger Dowex 1x4 were used separately for distinguishing broadly meant the cationic metal fraction and the fraction of stable anionic metal complexes, respectively, after retention of metal species and their exhaustive elution by means of a 4.0 mol l⁻¹ HCl solution. The third fraction, referred to the residual metal species, was retrieved by difference between total soluble metal contents and sum of metal quantities in separated cationic and anionic fractions. The fractionation pattern observed for both metals was described and discussed.     

Alkynylcyclohexadienyl tricarbonyliron complexes: A new directing effect for organoiron-mediated synthesis

The first example of an alkyne-substituted tricarbonyl(η⁵-cyclohexadienyl)iron(1+) complex has been prepared and the ω directing effect of the phenylethynyl substituent has been demonstrated in nucleophile addition reactions. Addition of NC⁻ also occurs at the a position to form an unusual η¹, η³-structure.     

微波溶样肉桂基荧光酮和表面活性剂连续荧光测定葡萄酒中铁和钴

观察到肉桂基荧光酮(略作CF)在pH≈8与Fc(Ⅲ)配位后荧光增强,CPB的加入使荧光更强,络合物与试剂荧光强度之比F_(FeR)/F_R随0～0.01μg/ml Fe(Ⅲ)线性变化,λ_(ex)=410nm,λ_(ex)=480nm;而CF在pH≈10与Co(Ⅲ)配位后荧光却减弱,乳化剂OP存在时使试剂荧光增强,若以荧光熄灭Co(Ⅲ)灵敏度便提高,试剂与络合物荧光强度之比F_R/F_(CoR)对0～0.016 μg/ml Co(Ⅲ)呈直线关系,λ_(ex)=300nm,L_(em)=352nm。控制化学条件和激发、发射波长,可不经分离测定葡萄酒(微波溶样)中铁和钴。