Ortho-phenanthroline

One important group of colour indicators is derived from 1 10 phenantholine ortho-phenanthroline) which forms a 3 1 complex with iron(II). The complex known as ferroin undergoes a reversible redox reaction accompanied by a distinct colour change... 

Ferroverdin can be crystallized following chromatography on alumina. C3oH2o08N2Fe-H20. No decomp. <300°. Moderately soluble in alcoholic solvents, sparingly soluble in ether and practically insoluble in water. Rf in n-butanol-pyridine-water 60 40 30, 0.91. Rt values known in three other solvents. Absorption peaks in the visible at approximately 4300 and 6750 A with amM = 8.2 and 8.8, respectively. Iron is diamagnetic (36) and resistant to EDTA, dipyridyl, ortho-phenanthroline and l-nitroso-2-napthol-3,6-disulfonic acid. The color is discharged with Na2S204 and other reductants but is unaffected by various oxidative treatments. 

Assay With the aid of about 25 mL of water, transfer about 125 mg of sample, accurately weighed, into a 300-mL Erlenmeyer flask. Add 50.0 mL of 0.5 A potassium dichromate, mix, then carefully add 100 mL of sulfuric acid, and heat to boiling. Remove the flask from the heat, allow the solution to stand at room temperature for 15 min, cool it in a water bath, and transfer the solution to a 250-mL volumetric flask. Dilute with water almost to volume, cool to 25°, dilute to volume with water, and mix. Titrate a 50-mL aliquot with 0.1 A ferrous ammonium sulfate, using 2 or 3 drops of ortho-phenanthroline TS. Perform a blank determination (see General Provisions), and make any necessary correction. Calculate the normality, A, of the ferrous ammonium sulfate solution by the formula... 

Figure 2 Comparison of ion-exchanger phase and solution phase spectral patterns obtained from the same species, the Fe(II)-ortho-phenanthroline complex (from Ref. 29) A Fe(phen)3 sorbed in Dowex 50W-X2 B Fe(phen) in aqueous solution.

For this purpose it was necessary to have, in the organic phase, a reagent able to neutralize the tripositive charge of the orthophenanthroline metallic species. We chose nonanoic acid which has poor solubility in aqueous phases. Nitrobenzene is suitable as a diluent because it solubilizes orthophenanthroline. The results of Eu [III] and Am (III) extraction in the nitrobenzene/ortho-phenanthroline/nonaoic acid mixture are given in Table III. 

COMPLEX TRI(ORTHO-PHENANTHROLINE)NICKEL(II) PATH LENGTH 1 DECIMETER SOLVENT WATER TEMPERATURE 23° C. CONCENTRATIONS COMPLEX - 0.02 MOLAR... 

Fig. 6. Design of the LB film spin-transition complex, [(OP3)2Fe (NCS)2l, where OP = substituted ortho-phenanthrolines (1,2, 3).

When silver nitrate is reacted with the molecular base ortho-phenanthroline, colorless crystals form that contain the transition-metal complex shown below, (a) What is the coordination geometry of silver in this complex (b) Assuming no oxidation or reduction occurs during the reaction, what is charge of the complex shown here (c) Do you expect any nitrate ions will be present in the crystal (d) Write a formula for the compound that forms in this reaction, (e) Use the accepted nomenclatiu e to write the name of this compoimd. 

The Pfeiffer Effect (1) is the change in optical rotation of a racemic mixture of an optically labile complex when it is placed into a solution containing one enantiomer of an optically active compound (known as the "environment substance"). For example, if an aqueous solution of /evo-malic acid is added to a solution of a racemic mixture of an optically labile complex, such as D,L-[Ni(phen)3]Cl2 (phen = ortho-phenanthroline), a marked change in optical rotation of the system is observed (the "Pfeiffer Effect"), and this rotation continues to undergo change over a period of about 120 hours. It should also be noted here that if the same malic acid solution is added to a racemic mixture of an optically stable complex, e.g., [Co(en)3]Cl3 (en = ethylenediamine), no such change in optical rotation is observed. 

The nature of the halide binding sites in LADH have been in dispute. Ward and Happe (74) assumed that Cl did coordinate directly to the zinc atom at the active site. On the other hand Lindman et al. (73,76,77) concluded that halide coordination to the zinc, if it occurs, has no influence on the halide ion relaxation rate. Their conclusions were based on results from halogen NMR studies in the presence of ligands believed or known to coordinate to the zinc in the active site. Thus neither oxy-quinoline nor ortho-phenanthroline affect the chloride ion relaxation. 

Diphenyl-lead dichloride complexes with such ligands as pyridine (1 2), dimethylsul-phoxide (1 2), l,l -dipyridyl (1 1), and ortho-phenanthroline(1 1) to produce octahedral... 

The two ligands that have been most extensively studied are ortho-phenanth-roline and 2,2 -bipyridyl. Both of these ligands are bidentate and are only weakly basic. With ortho-phenanthroline the maximum number of bound ligands is four when the anion is the perchlorate ion (Krishnamurthy and Soundararajan, 1966). The tris-complex with one coordinated perchlorate ion (as indicated by the infrared spectrum) has also been obtained (Grandey and Moeller, 1970). There do not appear to have been any dipyridyl complexes with the lanthanide perchlorates prepared at the present time, although there does not seem to be any reason they would not form. 

For both of these ligands the complexes formed when the acetates, chlorides, nitrates, and thiocyanates are used as the starting materials have a smaller number of organic ligands, coordination of some or all of the anions (the structure of the ten-coordinate complex [La(o-phen)2(N03)3] has been discussed earlier, section 3.9), and perhaps may be solvated as well (Forsberg, 1973). Most of the preparations can be carried out in aqueous or anhydrous ethanol. The existence of the lanthanide-nitrogen bond is clearly implied in these compounds and the infrared spectra (Sinha, 1964) and ultimately, complete structure determination, have verified that this interaction does take place. It should also be noted that both of these molecules form adducts with the tris-j8-diketone complexes and the structures of two of these with ortho-phenanthroline have been determined (Watson et al., 1972 Cunningham, 1973). 

The terdentate ligand, terpyridyl, follows the same pattern as bipyridyl and ortho-phenanthroline (Durham et al., 1969). The maximum number of coordinated ligands (three) occurs with the perchlorate. Since only ionic perchlorate was observed in the infrared spectrum, the molecule was presumed to be nine-coordinate. The emission spectrum of the europium complex was consistent with the expected D3 symmetry with a very slight distortion and this has been confirmed by a complete structure determination (Frost et al., 1969). 

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