Nuclear magnetic resonance parameters in water dimer

Teemu Sakari Pennanen, Perttu Lantto, Mikko Oskari Hakala, Juha Vaara

Tutkimustuotos: ArtikkelijulkaisuArtikkeliTieteellinenvertaisarvioitu


The changes in the computed nuclear magnetic
resonance (NMR) parameters of the water dimer with
respect to their monomer values were monitored as the
geometry of the dimer was systematically varied. Nuclear
magnetic shielding constants, shielding tensor anisotropies,
nuclear quadrupole coupling constants and spin–spin coupling
constants for the hydrogen bond donor and acceptor
molecules were calculated at hybrid density-functional
theory level. The dimer geometry was specified through
the intermolecular oxygen–oxygen distance ROO and the
hydrogen bond angle a. A grid of 120 geometries was
selected by systematically varying these two parameters.
The other geometrical parameters of the dimer were allowed
to relax, keeping the two parameters fixed. As the dimer
geometry was varied, all NMR parameters were observed to
be smoothly behaving. Characteristic changes as a function
of the intermolecular geometry were observed. These
include, besides the well-known deshielding of the donor
hydrogen shielding constant, also influences on the donor
deuterium quadrupole coupling constant, as well as the
shielding anisotropy of the donor and acceptor oxygens. We
discuss the contributions to the total dimerisation effect
from, on the one hand, the dominant direct interaction effect
at a fixed geometry and, on the other hand, from the quantitatively
relevant indirect, geometric effect. A fundamental
ambiguity of this partitioning is demonstrated. By forging
the general, smooth trends in all the studied NMR parameters
into a specific geometric definition, we find our data
to be in agreement with the widely used distance criterion for
hydrogen bonding in water, ROO B 3.5 A ° .
LehtiTheoretical Chemistry Accounts
DOI - pysyväislinkit
TilaJulkaistu - 2011
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä, vertaisarvioitu


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