Atomic and bond dipoles

It is interesting that the total dipole moment can be decomposed into atomic and pairwise contributions  

The molecular dipole moment can be represented as the sum of the individual atomic dipole moments and the pairwise atomic dipole contributions. 

The is large, when k and / belong to the aioms forming tue chemical bunds (if compared to two non-bonded atoms, see Appendix S, p. 1015), therefore the dipole moments related to pairs of atoms come practical unique fiom chemical bonds. The contribution of the lone pairs of the atom A is hidden in the second term of and may be quite large (cf. Appendix T on p. 1020). 

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Coordinate System Dependence Hartree-Fock Approximation Atomic and Bond Dipoles Within the ZDO Approximation How to Calculate the Dipole Polarizability (4[Pg.720]

As we have seen by comparing C02 and H20, the shape of a polyatomic molecule affects whether or not it is polar. The same is true of more complicated molecules. For instance, the atoms and bonds are the same in c/s-dichloroethene (28) and frans-dichloroethene (29) but, in the latter, the C—Cl bonds point in opposite directions and the dipoles (which point along the C—Cl bonds) cancel. Thus, whereas c/s-dichloroethene is polar, traws-dichloroethene is nonpolar. Because dipole momenrs are directional, we can treat each bond dipole moment as a vector. The molecule as a whole will be nonpolar if the vector sum of the dipole moments of the bonds is zero. 

In SIBFA, electrostatics is computed upon using distributed multipoles (monopoles, dipoles, quadupole) located on atoms and bond midpoints as ... 

Williams, D. E. 1988. Representation of the Molecular Electrostatic Potential by Atomic Multipole and Bond Dipole Models. J. Comp. Chem. 9, 745. 

Williams, D. E. 1990. Alanyl Dipeptide Potential-Derived Net Atomic Charges and Bond Dipoles, and Their Variation with Molecular Conformation. Biopolymers 29, 1367-1386. 

A similar reaction was not observed for 4-pentene-l-ol. It should be noted that a Pt(III) dimer complex is released after the reaction in Eq. (18), which is in contrast to the release of olefin and a Pt(II) dimer complex in aqueous solution by reductive elimination (Eq. (16)). The difference of such reactivity depending on the alkyl and the solvent would be caused by the difference of the electron density of the a-carbon atom and the dipole structure along the Pt-Pt bond in the solvents of different polarities. In aprotic organic solvent, the electron distribution along the Pt-Pt bond would be less polar, i.e., close to... 

Atomic Charges and Bond Dipoles, and Their Variation with Molecular Conformation. 

Table 12 Goodness-of-Fit of PD Atomic Multipole Expansions and Bond Dipole Models ...

D. E. Williams, /. Comput. Chem., 9, 745 (1988). Representation of the Molecular Electrostatic Potential by Atomic Multipole and Bond Dipole Models. See also, D. E. Williams, in Reviews in Computational Chemistry, Vol. 2, K. B. Lipkowitz and D. B. Boyd, Eds., VCH Publishers, New York, 1991, pp. 219-271. Net Atomic Charge and Multipole Models for the Ab Initio Molecular Electric Potential. 

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