Analysis of intramolecular hydrogen bonding in terms of the topological properties of the charge density. The protonated fluoroacetones

Abstract

. 64, 2042 (1986). A new method for the analysis of intramolecular hydrogen bonding is proposed and applied to the equilibrium structures of the protonated fluoroacetones. The method, based on a theory of molecular structure due to Bader, uses the topological properties of the charge density to elucidate the types of interactions within a molecule of interest. The calculations show a strong basis set dependence. In particular, the STO-3G optimized geometries exhibit intramolecular hydrogen bonding between a fluorine substituent and the carbonyl proton, whereas some calculations with geometries optimized at the 4-31G and 6-31G* levels indicate a direct bonding interaction between the fluorine and oxygen atoms. Two types of catastrophe point, namely conflict and bifurcation, are possible in protonated monofluoroacetone. Only the latter was located in the present calculations.

Differential reactivity of carbohydrate hydroxyls in glycosylations. I. Intramolecular interaction of the 5′-hydroxyl group with the heteroaromatic base in a model compound of 2′-deoxycytidine

“…This involves the topological analysis of the electronic density distribution, which can be used to analyze intramolecular hydrogen bonding between the hydroxyl group with the oxygen atom of the carbonyl group of model compound 2 to gain some insight into the reactivity of 5'-OH. Although the topic of intramolecular hydrogen bonding has been widely studied (5) experimentally and theoretically, it has only recently been analyzed by using Bader-type topological analysis of charge density distribution (28,40). The topological properties of the electronic density distribution are based on the gradient vector field of the electronic density Vp(r), and on the Laplacian of the electronic density Vlp(r).…”

Transition‐Metal Complexes with (C–C)→M Agostic Interactions

“…As examples of the first case, the QTAIM approach points to anion–anion bonding in a variety of halide salts, and to bonding between Cs + ions in CsSrF 3 or CsBaF 3 . Likewise, QTAIM bonds are found between oxygen atoms of adjacent nitro groups in the C(NO 2 ) 3 – ion and between hydrogen atoms forced to be in close proximity to one another, as in polycyclic aromatics,, as well as between halogen atoms in polyhalogenated organic molecules, between oxygen and fluorine atoms in protonated fluoroacetone compounds, and between nitrogen atoms in diaminoguanidinium cations . It may be that in these situations the systems work to reduce repulsions by having the interacting electron densities concentrate themselves more between the formally nonbonded pairs of atoms, thereby mimicking chemical bonds and generating the bond paths, despite the interaction being unfavorable.…”