Nitrogen bond order

Their combination implies a highly delocalized n system and an uranium-nitrogen bond order between two and three. 

In general, the metal-nitrogen bond orders of metal-nitrosyl complexes are larger (i.e., the M-N bonds are stronger) than the metal-carbon bond orders for the corresponding... 

T system, the PPP a—-tt method (133). The -tt and a net charges and bond orders of thiophene and thiazole are compared in Table 1-5. Whatever the method considered the variation of the indices occurs in the same sense when passing from thiophene to thiazole the replacement in the 3-position of a carbon atom by a nitrogen induces... 

Summarizing, the introduction of nitrogen at the place of C-3 in thiophene does not deeply disturb the electronic environment of the sulfur atom, but it induces in the rest of the molecule some alternating modification of the electronic density (Figs. 1-3 and 1-4). The perturbations induced by the nitrogen in the tt bond order of thiophene are... 

Typical coupling constants for isothiazoles are given in Table 5. The electronegative nitrogen atom reduces 3,4 and V3.5 from the values of 3.50 Hz and 0.27 Hz, respectively, in thiophene. The V values correlate quite well with rr-bond orders calculated by MO methods (74CJC833). 

There are only a few fimctional groups that contain an unpaired electron and yet are stable in a wide variety of structural environments. The best example is the nitroxide group, and numerous specific nitroxide radicals have been prepared and characterized. The unpaired electron is delocalized between nitrogen and oxygen in a structure with an N—O bond order of 1.5. 

Some of the scatter within the groups is undoubtedly due to differences in bond order and also to whether or not the nitrogens are located in the same ring. Nevertheless, some striking exceptions are apparent in which the pA values are much higher than expected. These include quinazoline, 1,3,5-, 1,3,7-, 1,3,8-, and 1,4,6-triazanaph-thalene, pteridine, and 1,4,5,8-tetraazanaphthalene. In all these cases, covalent hydration of the cation has been shown to occur, so the measured pA values are, in fact, equilibrium values involving both hydrated and anhydrous species. The hydrated species are, without... 

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