Valence Topological Charge-Transfer Indices for Reflecting Polarity: Correction for Heteromolecules

Molecules

关键词: Charge distribution;    Dipole moment;    Heteroatom;    Isolelectroic series;    Valence topological charge-transfer index;   

DOI  :  10.3390/10020334

来源: mdpi

【 摘 要 】

Valence topological charge-transfer (CT) indices are applied to the calculation of dipole moments μ. The μ calculated by algebraic and vector semisums of the CT indices are defined. The model is generalized for molecules with heteroatoms and corrected for sp³-heteromolecules. The ability of the indices for the description of the molecular charge distribution is established by comparing them with μ of the valence-isoelectronic series of cyclopentadiene, benzene and styrene. Two CT indices, μ_vec (vector semisum of vertex-pair μ) and μ_vec^V (valence μ_vec) are proposed. The μ_vec^V behaviour is intermediate between μ_vec and μ_experiment. The correction is produced in the correct direction. The best results are obtained for the greatest group. Inclusion of the heteroatom in the π‑electron system is beneficial for the description of μ, owing to either the role of additional p and/or d orbitals provided by the heteroatom or the role of steric factors in the π‑electron conjugation. The steric effect is almost constant along the series and the dominating effect is electronic. Inclusion of the heteroatom enhances μ, which can improve the solubility of the molecule. For heteroatoms in the same group, the ring size and the degree of ring flattering are inversely proportional to their electronegativity.

【 授权许可】

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