CLOPPA-IPPP Analysis of Electronic Mechanisms of Intermolecular ^1hJ(A,H) and ^2hJ(A,D) Spin−Spin Coupling Constants in Systems with D−H···A Hydrogen Bonds

Abstract

The electronic origin of intermolecular (2h)J(A,D) and (1h)J(A,H) couplings is discussed by means of the CLOPPA-IPPP approach in several model complexes with D-H...A hydrogen bonds. It is found that the origin of these couplings is mainly due to the interaction between the acceptor sigma lone pair and vacant molecular orbitals localized in the D-H...A moiety, regardless of the donor and acceptor nuclei. The problem of the larger absolute value of (2h)J(A,D) compared to (1h)J(A,H) is also addressed.

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

“…As an example, Contreras et al have developed a method known as inner projection of the polarization-propagator contributions from localized orbitals within the polarization-propagator approach (IPPP-CLOPPA) [214]. Among the recent applications of this method, we note an analysis of spin-spin coupling constants across hydrogen bonds [215]. In another approach, natural bond orbitals (NBOs) are used to analyze coupling constants [216].…”

IPPP-CLOPPA Analysis of the Influence of the Methylation on the Potential Energy and the Molecular Polarizability of the Hydrogen Bonds in the Cytosine–Guanine Base Pair

“…Unless explicitly stated, the vacant LMOs localized in each HB zone are joined together and indistinctly referred to as HB* LMOs, σ or π. As it was shown before, − they are physically significant in the hydrogen bond formation.…”

Theoretical developments and applications of polarization propagators

“…During the last few decades the CLOPPA model was applied to the study of different response properties, searching for a deeper understanding of the electronic mechanisms that underlies them …”

“…During the last few decades the CLOPPA model was applied to the study of different response properties, searching for a deeper understanding of the electronic mechanisms that underlies them. [18,132,133] In this section, we shall show two applications of the last development of such model, named as Loc-SOPPA due to it refers to the use of localized MOs at second order level of approach of polarization propagators. [40,52,53,134] Our aim is to show how the information of the main coupling pathways, described by LMOs, can be used to understand the way two external perturbations are transmitted through the electronic mechanism of molecules.…”