Diazapyrene

The classical Weitz-type redoxsystem If can be transformed into 11 or by formal insertion of one or two vinylene groups. Although the ir-system is considerably enlarged by this operation, Ej and E2 and therefore Ksem are hardly changed (Fig. 5). 

At first sight these results seem to be inconsistent with those of the corresponding hydrocarbons. These are more easily reduced with enlarged ir-systems, namely biphenyl (E2 -2.60V ), phenanthrene (E2 -2.44V ) and pyrene (E2 -2.08 Simple HMO-calculations demonstrate, however, that the high electron affinity of the N-atoms in If, 11 and 12 changes the sequence of the MO s in such a way that symmetry as well as energy of the LUMO s are altered only to a small extent  

The bisquatemary salts iiox of the isomeric phenanthrolines were also investigated in order to test the generality of structure A. Again, a reversible two step reduction of these isomers is only to be expected if the two N-atoms are connected by an even number of C-atoms, so that i REo could be formulated in a quinoid structure. 

This is the case for 11,13a-c, 13B2 and 13B3, but not for 13d and 13e Isomers with N—CH3 in position 1 had to be excluded because of rapid dimethylation even in organic solvents. In Table 2 results of rapid cyclic voltammetry are accumulated, which conespond to those obtained earlier by DC-polarography 

As can be seen from Table 2 the situation is more complex than anticipated. Except for the already discussed Uqx the electron transfer SEM/RED (E2) is not or poorly reversible. Thus reliable Ksem s can only be derived from some of these potentials. 

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Pyrimidine 1 is the lUPAC accepted name for 1,3-diazabenzene, while quinazoline 2 is the accepted name for benzo[r lpyrimidine or 1,3-diazanaphthalene. Perimidine 3 is the lUPAC accepted name for l//-benzo[r/ ]quinazoline or H -naphtho[l,8-r/i ]pyrimidine, while benzo. 4]perimidine 4 is also known as 1,3-diazapyrene. 

Coverage of perimidine chemistry can be found in two review articles <1981RCR816, 1995AQ151>, while benzo[g/5]perimidine chemistry is discussed in a review of diazapyrenes <2003CHE1417>. 

The question of whether 1 Ob, 1 Oc-diazapyrene (101) is capable of a finite existence has been the subject of theoretical considerations. According to HMO calculations, 100 was suggested to be the more stable valence tautomer."7 [2,2](2,6)Pyridinophane (99) was prepared in different reaction sequences by Baker et al. Their intention was to synthesize 100 however, owing to lack of material, it was impossible to investigate possible routes for converting 99 into 100.118... 

A six-membered ring is formed in the reduction of 2-nitrobiphenyl-2 -carboxylic acid68 or 6,6 -dinitrobiphenyl-2,2 -dicarboxylic acid.69 In the former case a phenanthridine is formed, in the latter a 4,9-diazapyrene. Similarly, a seven-membered ring is obtained when 2-nitro-2 -isothiocyano-biphenyl (15) is reduced in acidic solution with the formation of 6-mercapto-dibenzo[d/]-l,3-diazepine 3-oxide (16)70 [Eq. (28)]. 

The outer-sphere electron transfer reaction between [Fe(CN)6] and [Co(NH3)5H20] has been studied as a function of temperature and pressure in a variety of water-glycerol solvent mixtures. While AV remains essentially constant at 28 cm moP both A/f and A5 increase with an increase in the viscosity of the solvent. The intramolecular electron transfer processes in (NH3)5CoLFe(CN)5 complexes, where L is 3,3 -dimethyl-4,4 -bipyridine, 4,4 -bipyridylacetylene, 2,7-diazapyrene, and 3,8-phenathroline, have been studied. The activation free energies display an inverse dependence on the Fe-Co distance and, when corrected for solvent reorganization energies, are relatively constant at 14.0 0.5 kcal moP. ... 

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