Cations with drawing

The foregoing results indicate that a powerful anchimeric rate-accelerating effect (38) must operate in the transition state of the electrophilic substitutions of II which exceeds the electron-with drawing effect of the immonium form D in the mono-positive cation II ... 

X is NR R2. The substituent is converted to a Z substituent via the low-lying a orbital, and the ring is deactivated toward further electrophilic attack. The ortho and para channels lead to products. The interaction diagram for an X -substituted pentadienyl cation, substituted in the 1-, 2-, and 3-positions, as models of the transition states for the ortho, meta, and para channels, are too complex to draw simple conclusions. The HOMO and LUMO of the three pentadienyl cations with an amino substituent are shown in Figure 11.3. Notice that the LUMO of each is suitable to activate the C—H bond at the saturated site toward abstraction by the base. Curiously, the meta cation has the lowest LUMO and should most readily eliminate the proton. The stabilities of the transition states should be in the order of the Hiickel n energies. These are 6a — 8.7621/ , 6a — 8.499 / , and 6a — 8.718 / , respectively. Thus the ortho and para channels are favored over the meta channel, and the ortho route is slightly preferred over the para route. Experimentally, para substitution products are often the major ones in spite of there being two ortho pathways. The predominance of para products is usually attributed to steric effects. 

General Description of the Structures. The x-ray structural determinations of the four compounds revealed discrete anions and cations with normal interionic separations and with stoichiometries consistent with the analytical and spectral data. Shown in Figures 1 and 2 are ORTEP drawings of the... 

Look at Uie drawings accompanying Problem 3.6. Is it possible to superimpose the cube on the dodecahedron Castieman and coworfcers have recently detected a cation with mje = 28, identified as TigC. It b bebeved that the titanium atoms form a cube with the addition of twelve carbon atoms to complete a pentagonal dodecahedron. Draw the proposed structure. What e its point group symmetry ... 

Draw the frontier orbital interactions for the all-suprafacial cycloaddition of an allyl anion to an alkene and for an allyl cation to a diene showing that they match, and show that the alternatives, allyl cation with alkene and allyl anion with diene are symmetry-forbidden. 

Fig. 24. ORTEP drawing of the Os/ N2)(NH3 J.MeCN ),f cation with atomic numbering scheme. From Ref. (151).

Why draw the oxyallyl cation with this stereochemistry ... 

Draw one canonical form for each of the following aromatic compounds a three-membered carbocyclic cation with 2 electrons (n=0, 3 p sub-orbitals) a five-membered carbocyclic anion with 6 electrons (n= 1, 5 p sub-orbitals) and a six-membered neutral ring containing one nitrogen atom and five carbon atoms (n= 1, 6 p sub-orbitals). 

Although halides, particularly Cl, are strong like character, their n-donating ability... 

Rule I. You can draw a polyhedron of anions around every cation in a crystalline lattice, such that (i) the interionic separation can be determined as the sum of the ionic radii, according to Equation (12.10), and (ii) the coordination number of the cation can be determined using the radius ratio rule (vide infra). The radius ratio rule sets the minimum r+/r ratio that can exist for a cation with a given ccxjrdina-tion number. This ratio can be determined from a geometrical consideration of the minimum cationic radius necessary to keep the anions in a particular coordination geometry from just touching each other. 

Dry residue (solid residue) is a characteristic of soil salinity, it is determined by the ratio of anions and catiorts in the soil solution. In normal conditions it can t exceed 0.30%, in soil samples it is equal to 0.35%. Salinity is determined by salt content in soil solution. Salts ate need to be formed mostly sodiiun, calcium and magnesium cations with chloric and sirlfuric anions. Potash cations, bicarbonate, carbonate and nitrate anions can make insignificarrt part. Thrrs results by dry residue in soil, which were obtained in this experiment, allow drawing conclusion that anion and cation amount is optimal and they are the main compotrrtds of the soil in cirrrerrt agroclimatic conditions. 

Examine each of the following cations and draw a second structure with an X=X bond (resonance stabilized) where it is appropriate. If no X=X structure is possible, briefly explain why not ... 

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