Nitrous Lewis structure

Below are two different Lewis structures for nitrous acid (HN02). Which is foe better Lewis structure based only on formal charge ... 

Linus Pauling, Proc. Nat. Acad. Set., 18, 293 (1932). Examples of molecules which resonate among several Lewis structures are given in this paper. Further discussion of the nitrous oxide molecule is given in a later note, Linus Pauling, ibid., July, 1932. 

Let s work two examples illustrating the steps necessary to produce a good Lewis structure. We will take HN02 and XeF4 for these examples. The first molecule is nitrous acid. It is an example of an oxyacid. (Oxyacids are compounds containing hydrogen, oxygen, and one other element.) The other compound is xenon tetrafluoride. 

There is more than one way to arrange the atoms in nitrous acid. However, only one will lead to a good Lewis structure. You should avoid any arrangement that places identical atoms adjacent. Identical atoms, other than carbon, rarely bond... 

Probtom 1.6 Write Lewis structures for (a) hydrazine, N,H4 (6) phosgene, COCl (c) nitrous acid, HNOj. 

To return now to nitrous oxide. N,0. specifically structure 1, we have a Lewis structure ... 

Nitrous oxide is a good example of a molecule that shows resonance. The structure on the left in Figure 7.6 has two double bonds, with two lone pairs on each of the distal atoms. The structure on the right has a triple bond. Neither structure fully describes nitrous oxide, nor does either structure actually exist. The real nitrous oxide molecule is a resonance hybrid of the two Lewis structures. 

For many simple compounds having no more than one double bond, the modern picture may be quite adequately represented by the Lewis structures (although the Lewis rules are noncommittal about the shapes of molecules). For compounds such as butadiene, benzene, and nitrous oxide, where there is extensive delocalization of electron density, the Lewis structures are not as suitable as the x-electron structures or, better still, as the streamer structures. Both of the latter type, however, are more difficult to draw and, for more complex molecules, more difficult to visualize they become extremely unwieldy when one attempts to use them to represent the progress of a chemical reaction. 

Specify a possible cause for the instability of carbonic acid. Nitrous oxide (N20) has three possible Lewis structures ... 

The Lewis structure of linear nitrous oxide molecule is shown below. However, unlike similarly linear CO2 with which it is isoelectronic, NiO does not have a centre of symmetry. Therefore, the exclusion rule does not apply, and a band that is IR active can be Raman active as well. 

Determine the Lewis structures for nitrous acid, (HO)NO, and the nitrite ion, N02 . Does either exhibit resonance ... 

Nitrous oxide (N2O) has three possible Lewis structures ... 

PROBLEM 23.39 Reaction of A -phenylalanine (1) with nitrous acid affords A -nitroso amino acid (2), which on treatment with acetic anhydride yields sydnone (3). Sydnones belong to a class of compounds known as mesoionic compounds. These compounds cannot be satisfactorily represented by Lewis structures not involving charge separation. The name sydnone derives from the University of Sydney where the first examples were prepared in 1935. Reaction of 3 and dimethyl acetylenedicarboxylate (DMAD) gives pyrazole (4). Propose mechanisms for the formations of 2, 3, and 4. Hint. For the formation of 4, it may be helpful to consider the other possible Lewis structures for sydnone 3. 

Two known compounds have the formula HgNgOg. One of them is a weak acid and one is a weak base. The acid, called hyponitrous acid, has two O—H bonds. The base, called nit-ramide, has no O—H bonds. Draw Lewis structures for these compounds. Predict whether the acid is stronger or weaker than nitrous acid and whether the base is stronger or weaker than ammonia. 

Dinitrogen oxide (nitrous oxide, or "laughing gas") is sometimes used as an anesthetic. Here are some data about the N2O molecule N—N bond length = 113 pm N—O bond length = 119 pm. Use these data and other information from the chapter to comment on the plausibility of each of the following Lewis structures shown. Are they all valid Which ones do you think contribute most to the resonance hybrid ... 

PRACTICE EXAMPLE B A reference source on molecular structures lists the following data for dinitrogen monoxide (nitrous oxide), N2O Bond lengths N—N = 113 pm N—O = 119pm bond angle = 180°. Show that the Lewis structure of N2O is a resonance hybrid of two contributing structures, and describe a plausible hybridization and bonding scheme for each. 

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