Theoretical Study on Pyramidal C7N6–H3R3 Molecules

2019 ◽  
Vol 72 (7) ◽  
pp. 501 ◽  
Author(s):  
Bing He ◽  
Bingke Li ◽  
Hongwei Zhou

The pyramidal molecule C7N6H6 and its nine symmetric tri-substituted derivatives C7N6–H3R3 (R=OH, F, CN, N3, NH2, NO2, N=NH, N2H3, and C≡CH) were investigated computationally using the GAUSSIAN 09 program package. Natural bond orbital and atoms in molecules analyses, as well as valence bond theory were applied to investigate the bonding properties. In comparison to their well known analogues C6N7–R3, i.e. generic heptazines, it is found that these 10 molecules are all reactive. Further studies on the topological structures and ionization energy values indicate that the reactive site of the molecules is located at the carbon atom of the core frame. Even though C7N6–H3R3 are neutral molecules, the structures and properties of some are consistent with those of a carbanion, and indeed, they act like carbanions, or so-called carbanionoids. These carbanionoids may have an extensive impact in organic chemistry and organometallic chemistry.

This and two of three parts to be published subsequently are concerned mainly with the so-called valence-bond theory of conjugated and aromatic molecules. An improvement to the method is described, which consists in adding to the usual set of structures some extra ones which are ‘polar’ in the sense that they show two of the π-electrons on one centre, and none on another centre, making these two centres carry respectively negative and positive charges. This adds a certain flexibility to the description of molecular states which is lacking when the electrons are supposed to be distributed one to each centre throughout. In this part a preliminary question is treated which bears on getting the new empirical parameters needed for including polar structures in the theory. This question is the assignment of the long wave-length bands in the spectrum of ethylene. The assignment is made with the help of a theoretical study of the ethylene energy levels in an approximation using antisymmetric molecular orbitals. Using this calculation as a guide, two transitions are assigned. A weak band, appearing at about 2000 Å, is taken to be 1 A g - 1 A g9 and a strong one, having its maximum at about 1630 Å, is taken to be 1 A g – 1 B lu .


2021 ◽  
Vol 23 (5) ◽  
pp. 3327-3334
Author(s):  
Remco W. A. Havenith ◽  
Ana V. Cunha ◽  
Johannes E. M. N. Klein ◽  
Francesca Perolari ◽  
Xintao Feng

Valence bond theory reveals the nature of the OC–C bond in carbon suboxide and related allene compounds.


ChemInform ◽  
2010 ◽  
Vol 26 (7) ◽  
pp. no-no
Author(s):  
E. C. DA SILVA ◽  
J. GERRATT ◽  
D. L. COOPER ◽  
M. RAIMONDI

1987 ◽  
Vol 87 (3) ◽  
pp. 1666-1676 ◽  
Author(s):  
David L. Cooper ◽  
Joseph Gerratt ◽  
Mario Raimondi ◽  
Maurizio Sironi

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