Dipole Correlation of the Electronic Structures of the Conformations of Water Molecule Evolving Through the Normal Modes of Vibrations Between Angular (C2v) to Linear (Dµh) Shapes

International Journal of Molecular Sciences

Dulal C. Ghosh¹ 

关键词: Atomic dipole;    hybridization;    lone pair;    localized orbitals;    energy partitioning;    barrier to inversion.;   

DOI  :  10.3390/i7030071

来源: mdpi

【 摘 要 】

In order to settle the issue of equivalence or non-equivalence of the two lone pairs of electrons on oxygen atom in water molecule, a quantum chemical study of the dipole correlation of the electronic structure of the molecule as a function of conformations generated following the normal modes of vibrations between the two extreme conformations, C_2v (ÐHOH at 90º) and D_µh (ÐHOH at 180º), including the equilibrium one, has been performed. The study invokes quantum mechanical partitioning of molecular dipoles into bond moment and lone pair moment and localization of delocalized canonical molecular orbitals, CMO’s into localized molecular orbitals, LMO’s. An earlier suggestion, on the basis of photoelectron spectroscopy, that one lone pair is in p-type and the other is in s-type orbital of O atom of water molecule at its equilibrium shape, and also the qualitative “Squirrel Ears” structure are brought under serious scrutiny. A large number of conformations are generated and the charge density matrix, dipole moment of each conformation is computed in terms of the generated canonical molecular orbitals, CMO’s and then Sinanoğlu’s localization method is invoked to localize the CMO’s of each conformation and the quantum mechanical hybridizations of all the bonds and lone pairs on O center are evaluated in terms of the localized molecular orbitals. Computed data demonstrate that the electronic structures i.e. two bond pairs and two lone pairs and its hybridization status of all conformations of water molecule are straightforward in terms of the LMO’s. It is further revealed that the pattern of orbital hybridization changes continuously as a function of evolution of molecular shape. The close analysis of the generated LMO’s reveals that one lone pair is accommodated in a pure p orbital and another lone pair is in a hybrid orbital in almost all conformations.

【 授权许可】

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