5-Methyl-1.10-phenanthroline-iron complex

For mixtures of the two oxidation states, the contact shifts depend directly on the relative mole fractions of the two states, indicating that the system is in the limit of rapid exchange. From this and the concentrations of the two species, one can calculate that the second-order rate constant involving the electron transfer must be greater than 106 M l seer1 at 25°C. This limit applies not only to the phenanthroline iron(II)—(III) system but also the iron(II)—(III) complexes with the following methyl derivatives of phenanthroline ... 

A stopped flow technique coupled with spectrophotometric analysis of the iron (II) complex formed has been used to investigate - the reactions of some organic complexes of iron(III) with the ion Fe ". The iron(III) was complexed with 1,10-phenanthroline, various substituted 1,10-phenanthrolines (5-methyl-, 5-nitro-, 5-chloro-, 5-phenyl-, 5,6-dimethyl-, 4,7-diphenyl-, and 3,4,7,8-tetramethyl-) and 2,2 -dipyridine, 4,4 -dimethyl-2,2 -dipyridine, and 2,2, 2"-tripyridine. The wavelengths used for the analysis lay in the region 500-552 m/i. 

Its oxidized form (Phen)3Fe3+ is pale blue, while the reduced form (phen)3Fe2+ is red. The transition potential is about 1.11 V. Among the substituted derivatives of phenanthrolines, 5-methyl- and 5-nitro-1,10-phenanthroline complexes of iron have found wide applications in redox titrations. 

Charton (J52) has also applied the extended Hammett equation to the oxidation-reduction potentials of 5-substituted phenanthroline complexes of iron in various acidic media (95, 97, 651) and of bis-5- and 4,7-substituted phenanthroline complexes of copper in 50% dioxane (404). Thus, one should expect an overall similarity between the variations in pAa, stability constant, and oxidation-reduction potential data for the various ligands. The variations in a and )3 values found for various substitution positions and the tautomerism in the LH+ ions show that the correlation need not be good. A similar point may also be made about the comparison of data for the transoid bipyridylium ions and their cis complexes. Plots of A versus pA for various systems (95, 404) show a linear dependence to differing extents. As would be expected, the data for analogous complexes of iron (28), ruthenium (214, 217, 531), and osmium (111, 218, 220) show very good correlation. The assumption (152) that the effects of substituents are additive is borne out by these potential data, where the changes in potential on methyl substitution are additive (97). 

Iron(II) in sea water forms complexes with 2,4,6-tripyridyl-sym-triazine or 4,7-diphenyl- 1,10-phenanthroline which are readily extracted with propylene carbonate (4-methyl-l,3-dioxolane-2-one). This extractant is colorless, nonhygroscopic, chemically stable, and more dense than water, but slightly soluble therein. Prior to complexa-tion the iron(III) has to be reduced to its divalent state by adding hydroxylammo-nium hydrochloride 67). 

Electropolymerization of 4-Vinylpyridine Complexes. Investigations of Structural and Electronic Influences on Thin Film Formation. The recent discovery of the reductive polymerization of complexes containing vinylpyridyl ligands (lg), such as Ru -(bpy)2(vpy)22+ has led to the preparation of homogeneous thin layers of very stable electroactive polymers. This method has been extended to 4-vinyl-4 -methyl-2,2 -bipyridine (lg, 21a) and 4-vinyl-l,10-phenanthroline (21b) on both ruthenium and iron. In the following section we discuss our results on thin films derived from the polymerizable ligands BPE and the trans-4 -X-stilbazoles, (4 -X-stilb X - Cl, OMe, CN and H). 

Iron(ii) complexes of 2-methyl-l,10-phenanthroline (L) have been prepared. FeL2X2 (X = Cl, Br, NCS, N3, or malonate) are all high-spin, the CNS complex containing N-bonded anions in a cis arrangement. FeL2(CN)2 is low-spin, and it is concluded that the crossover point for FeL2X2 is exactly at the position of L in the spectrochemical series, in contrast to the analogous... 

There was no indication of the presence of two isomers in this case. However, the detection of mer- and fac- isomers has recently been described for the tris (4-methyl-1,10-phenanthroline) and tris (4-methyl-2,2 -bipyridyl) complexes of ruthenium(II) [M. J. Cook, A. P. Lewis, G. S. G. McAuliffe, and A. J. Thompson, Inorg. Chim. Acta 64, L25 (1982)]. The possibility of the presence of both isomers should always be borne in mind in kinetic studies of tris-unsymmetrical diimine complexes, as indeed was shown many years ago in relation to SchilT base complexes of iron(II) [P. Krumholz, Inorg. Chem. 4, 609 (1965)]. 

The first example of iron-activated nucleophilic aromatic substitution on solid phase has been presented by Ruhland et al. [141], who attached [(cyclopentadienyl)-benzene Fe(II)] PF6 to polymer-bound piperazine (Scheme 55). The complex 68 was subjected to a variety of nucleophiles using different protocols. The decomplexation was achieved by irradiation in the presence of phenanthroline, and in the final step the resin-bound products were cleaved with methyl chloroformate to give corresponding carbamates in good yields. 

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