The Bond Localization Energies in the Aromatic Bismethano[14]annulenes

1997 ◽  
Vol 36 (7) ◽  
pp. 748-750 ◽  
Author(s):  
Maja Nendel ◽  
Kendall N. Houk ◽  
L. M. Tolbert ◽  
Emanuel Vogel ◽  
Haijun Jiao ◽  
...  
Keyword(s):  
Bond Localization

On the Reaction of 2,5-Dihydroxy-[1,4]-benzoquinone with Diamines – Strain-induced Reactivity Effects

2020 ◽  
Vol 24 ◽  
Author(s):  
Hubert Hettegger ◽  
Andreas Hofinger ◽  
Thomas Rosenau
Keyword(s):  
Nucleophilic Substitution ◽  
Product Structure ◽  
Carbonyl Groups ◽  
Reaction Products ◽  
Double Bonds ◽  
Oh Groups ◽  
Natural Geometry ◽  
Quinoid Structure ◽  
Bond Localization

: The regioselectivity of the reaction of 2,5-dihydroxy-[1,4]-benzoquinone (DHBQ) with diamines could not be explained satisfactorily so far. In general, the reaction products can be derived from the tautomeric ortho-quinoid structure of a hypothetical 4,5-dihydroxy-[1,2]-benzoquinone. However, both aromatic and aliphatic 1,2-diamines form in some cases phenazines, formally by diimine formation on the quinoid carbonyl groups, and in other cases the corresponding 1,2- diamino-[1,2]-benzoquinones, by nucleophilic substitution of the OH groups, the regioselectivity apparently not following any discernible pattern. The reactivity was now explained by an adapted theory of strain-induced bond localization (SIBL). Here, the preservation of the "natural" geometry of the two quinoid C–C double bonds (C3=C4 and C5=C6) as well as the N–N distance of the co-reacting diamine are crucial. A decrease of the annulation angle sum (N–C4–C5 + C4–C5–N) is tolerated well and the 4,5-diamino-ortho-quinones, having relatively short N–N spacings are formed. An increase in the angular sum is energetically unfavorable, so that diamines with a larger N–N distance afford the corresponding ortho-quinone imines. Thus, for the reaction of DHBQ with diamines, exact predictions of the regioselectivity, and the resulting product structure, can be made on the basis of simple computations of bond spacings and product geometries.

Bond localization approach to the carbon analog of the Claisen rearrangement. Thermolysis of 4-aryl-1-butenes

1979 ◽  
Vol 44 (9) ◽  
pp. 1480-1485 ◽  
Author(s):  
Joseph B. Lambert ◽  
Dietrich M. Fabricius ◽  
Julie Ann Hoard
Keyword(s):  
Claisen Rearrangement ◽  
Localization Approach ◽  
Bond Localization

Bond Localization Energy. I. Definition, Methods of Computation, and Relation to Bond Order

1949 ◽  
Vol 2 (4) ◽  
pp. 564
Author(s):  
RD Brown
Keyword(s):  
Bond Order ◽  
Theoretical Discussion ◽  
Localization Energy ◽  
Resonance Energies ◽  
The Relationship ◽  
Bond Localization ◽  
Activated Complex ◽  
Mobile Order

A new quantity-the bond localization energy-which has some advantages in the theoretical discussion of the chemical reactivities of various bonds, is introduced. Its relationship to the activated complex is indicated. It is shown to be expressible in terms of the resonance energies of certain molecules related to the molecule being considered. The various methods available for computing resonance energies by the LCAO method are outlined and some of these are used to derive numerical values for the localization energies of particular bonds. The relationship between bond localization energy and mobile order is investigated, and the significance of the relations thus found is indicated.

Bond localization in aromatic-iron carbonyl complexes

1970 ◽  
Vol 92 (3) ◽  
pp. 716-717 ◽  
Author(s):  
Raymond Edward. Davis ◽  
R. Pettit
Keyword(s):  
Iron Carbonyl ◽  
Carbonyl Complexes ◽  
Bond Localization

Fluctuating Double-Bond Localization and Charge Migration in ? Systems

1992 ◽  
Vol 75 (2) ◽  
pp. 539-556 ◽  
Author(s):  
Edgar Heilbronner ◽  
Sason Shaik
Keyword(s):  
Double Bond ◽  
Charge Migration ◽  
Bond Localization

Reducing zirconium(iv) phthalocyanines and the structure of a Pc4−Zr complex

2015 ◽  
Vol 44 (31) ◽  
pp. 13955-13961 ◽  
Author(s):  
Wen Zhou ◽  
Rachel H. Platel ◽  
Thiago Teixeira Tasso ◽  
Taniyuki Furuyama ◽  
Nagao Kobayashi ◽  
...  
Keyword(s):  
Reducing Agents ◽  
Bond Localization

Reduced Zirconium(iv) phthalocyanines were prepared from a variety of reducing agents (KC8, KEt3BH or LiCp*) and a reduced Pc4−Zr(iv) species was isolated and structurally characterized; it shows partial bond localization consistent with a reduction of the Pc ring.

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