Orthophenanthroline complexes

Orthophenanthroline complexes. As azides exhibit greater chemical affinity for trivalent actinide ions, we tried to check this behavior with a bidentate ligand. We chose 1-10 ghenantro-line which has two nitrogen donors at 2.75 A from each... 

Certain orthophenanthrolines may be used instead of 1,10-phenanthroline. These include 5-nitro-l,10-phenanthroline, Erioglaucin A, and p-ethoxychiysoidine which form iron-II complexes of violet-red, yellow-green, and red colors, respectively. 

Dipyridyl and orthophenanthroline form particularly stable complexes with iron. The octahedral [Fe(phcn)3] + ion (Fig. 2C4) is blood-red but is oxidised to pale blue [Fe(phen)3] without any structural change. for the system = 1.14 V, making the compound, also known as ferroin, a most useful redox indicator for the oxidation of Fe + ion Fe +/Fe + = 0.77 V) by cerium(IV) ion (E Ce +/Ce + = 1.45 V). 

This paper reports the results of investigations of the complex formation between actinide or lanthanide ions and azide or orthophenanthroline. The aim of this work was first to confirm whether these relatively soft ligands give complexes of different stabilities with the trivalent lanthanide and actinide ions, as a consequence of the broader extension of 5f orbitals as compared with 4f. Secondly, we attempted to use the results in actinide chemical separation processes. 

We studied the complexes of lanthanides and Am (III] by potentiometry. This method is based on pH variations due to the competition between H+ and the metal ions for the coordination site of orthophenanthroline (pka - 5.2], as shown by equation (4]. 

The calculation results are shown in table II. We also report formation constants determined from spectrophotometry for Ho and Nd, and by solvent extraction for Er. Without going into detail for these two methods, it may be noted that the results show fair agreement. That fact points out the inner sphere character of orthophenanthrolinium lanthanous complexes. The main absorption band of Am (III] is modified by the presence of orthophenanthroline. We used these spectral variations to calculate the formation constants of Am (III], as described in the previous paragraph. As for azide complexes, we observed that Am monoorthophe-nanthroline is more stable than the equivalent lanthanide complex, and for the bis orthophenanthroline species, the difference... 

A class of organic compounds known as 1,10-phenanthrolines, or orthophenanthrolines, form stable complexes with iron(II) and certain other ions. The parent compound has a pair of nitrogen atoms located in such positions that each can form a covalent bond with the iron(II) ion. 

Three orthophenanthroline molecules combine with each iron ion to yield a complex with the structure shown in the margin. 

The dichromate is reduced to chromic ion while the ferrous ion is oxidized to ferric ion. When all of the CraO has been reduced, it is possible for Fe + to exist in solution. An indicator called orthophenanthroline is added, which forms a red complex with Fe " and thereby detects the presence of... 

Certain positively charged ion-exchangers can be used for anion-selective electrodes. Charged metal salts of appropriately substituted orthophenanthrolines— M(o-phen)3 —result in good electrodes for nitrate, fluoroborate, or perchlorate by forming ion-association complexes with these anions. The CIO " electrode, in particular, has few interferences and perchlorate is a difficult ion to measure by almost any other method. A dimethyl-distearyl-ammonium ion, R N, can be used as an ion-exchanger in an electrode that has fair selectivity for chloride. 

Iron (the lower limit of this photometric determination is 0.1 ppm as Fe) Iron is reduced to the ferrous condition where it forms an orange-red complex with 1,10-phe-nanthroline (orthophenanthroline) in an acetate-buffered solution at pH 5. Intensity of the color so formed is measured at 510 nm in a photometer calibrated with standard iron solutions. The color develops within 15 min, is very stable, and follows Beer s law. 

Phenanthroline is also called orthophenanthroline. It forms a very stable complex with Fe +, intensively colored dark red, called ferroin (Fig. 16.2). 

In a very oxidizing medium, the orthophenanthroline/Fe + complex of a pale blue color is formed from ferroin. The corresponding half-redox equilibrium is... 

Misra and Mehta (1991) described the pseudo-hypersensitivity in complexes of Nd " " with fluorinated nucleic bases and with fluorinated nucleosides. Pr complexes with haloacetate, fluorocarboxylate, / -diketonates, diols and orthophenanthroline derivatives have been considered by Misra and Mehta (1992). The fluorocarboxylates of Pr " tend to have lower intensities for the f-f transitions with the increased number of fluorine ligands. This is understandable in terms of the electron withdrawing capacity of different fluoroalkyl groups (lower covalency). The increase in intensity in the order butane-1,4-diol electron density of the multiple bond with some sort of linear combination of Pr 5d, 6s, 6p and 4f orbitals. Misra et al. (1994a) studied 27 Nd complexes with the identical chromophore NdOeN2 (CN 8) in methanol, DMF, acetonitrile, and isopropanol. 

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