2- Methyl-l,10-phenanthrolines

Irving, Cabell, and Mellor found that 2-methyl-l,10-phenanthroline is a stronger base than 1,10-phenanthroline yet it forms weaker complexes with Fe(II). The relative instability of the Fe(III) complex with 1,10-phenanthroline compared with the Fe(n) complex also seems to be due, at least in part, to steric hindrance. Steric hindrance plays an important role in the use of the reagent 2-methyl-8-hydroxy-quinoline, which precipitates zinc and magnesium but not aluminum. ... 

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... 

Fig. 6 2,6-Bis(triazol-3-yl)pyridine, 2-triazolyl-l,10-phenanthroline, and their methyl-substituted derivatives...

Structure determinations of several Fe(II) compounds of 2-triazolyl-l,10-phenanthroline and its methyl-substituted derivatives proved that in addition to the two nitrogen donor atoms of the 1,10-phenanthroline entity, the N-4 of the 1,2,4-triazole ring participates in coordination, even when a methyl substituent occupies the position adjacent to this donor atom [15, 16]. All compounds obtained exhibit Fe(II) spin crossover behaviour, its extent depending on the nature of the anionic groups and the solvent content. 

Methyl-l,10-phenanthroline [3002-78-6] M 194.2, m 113 (anhydr). Crystd from benzene/pet ether. 

Not many reduction potentials are known for copper complexes. That of the Cu2+/Cu+ couple is 0.16 V Since lo(Cu+/Cu°) is 0.52 V, the disproportionation of Cu+ to Cu° and Cu2+ is favourable. This reaction does indeed occur, which makes is impossible to study stable copper(I) solutions. Reduction potentials of copper(II)-/copper(I)-(l,10-phenanthroline)2 and a few derivatives have been calculated from a kinetic analysis of appropriate rate constants values range from 108 mV for the 5-methyl-l, 10-phenanthroline complex to 219 mV for the complex with a nitro group at the 5 position [52], Values of 0.17 V and 0.12 V are given by Phillips and Williams [53] for the phenanthroline and bipyridine complexes, respectively. Such complexes can thermodynamically catalyse both the superoxide dismutation and the one-electron reduction of hydrogen peroxide (see below). 

Recently, we reported a terbium complex Tb(PMIP)3(PhCN) (Tb-29, PMIP= 1-phenyl-3-methyl-4-isobutyl-5-pyrazolone PhCN = pyrazino[2,3-/][l,10] phenanthroline-2,3-dicarbonitrile, Figure 13.13) as a reagent for anions [50]. Interestingly, the luminescent... 

The first phenanthroline to be prepared was 1,7-phenanthroline by Skraup and Vortmann in 1882, followed one year later by the synthesis of 4,7-phenanthroline. 2-Methyl-1,10-phenanthroline was the first 1,10-phenanthroline to be reported, the parent compound being synthesized 9 years later by Blau. 1,8-Phenanthroline was prepared in 1945. The synthesis of the 3,8-isomer was claimed in 1940, but there is doubt about the structure of the product. The remaining isomers, 1,9-, 2,7-, 2,8-, 2,9-, 3,7-, and authentic 3,8-phenanthroline, were not obtained until 1966, when Perkampus and Kassebeer formed all the phenanthrolines by irradiation of appropriate l,2-di(pyridyl)ethylenes. A derivative of 2,8-phenanthroline had, however, been synthesized 2 years earlier. ... 

Improvements in the double Skraup synthesis of 1,7-phenanthroline from m-phenylenediamine now enable a yield of 70% to be achieved. The Skraup reaction continues to be used for the synthesis of 1,7-phen-anthrolines starting from the substituted 5-aminoquinolines. 5-Chloro-6-hydroxy-1,7-phenanthroline (18) has been prepared in this way, and an improved synthesis of 6-hydroxy-1,7-phenanthroline was reported. As expected, the Skraup reaction on 5-aminoquinaldine affords 8-methyl-l,7-phenanthroline, not 2-methyl-l,7-phenanthroline as it was previously named. The extension of the Skraup reaction using methyl vinyl ketone instead of glycerol has been applied to 5-aminoquinoline to afford 4-methyl-l,7-phenanthroline. A related condensation using 2-hydroxymethylenecyclohexanone provides a route to benzo-substituted l,7-phenanthrolines. 7-Aminoquinoline with mesityl oxide in the presence of iodine gives 8,8,10-trimethyl-7,8-dihydro-l,7-phenanthroline (19)168... 

On the right side of Figure 2 we depict the formation of complex molecular orbitals in the [IrCL>(phen) (4,7-mephen)] ion. As before, tta and 7TB represent molecular orbitals on 1,10-phenanthroline and 4,7-di-methyl-l,10-phenanthroline, respectively, as do tta and ttb. The 4,7-dimethyl-1,10-phenanthroline orbitals are again placed above those of... 

Methyl-l,10-phenanthroline [3002-78-6] M 194.2, m 67 (monohydrate), 113 (anhydrous), pK 5.28. Crystallise it from berrzene/petroleum ether or from H2O as the monohydrate. It complexes with many metals. [Beilstein 23III/IV 1714.]... 

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