MARTINEZ fernando Ariel
Magnetic descriptors of hydrogen bonds in malonaldehyde and its derivatives
MONTERO, MARCOS DAVID ALEJANDRO ; MARTINEZ, FERNANDO; AUCAR, GUSTAVO ADOLFO
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
ROYAL SOC CHEMISTRY
The nature of the hydrogen bond, HB, as such is still unknown, though few of its most fundamental features has been uncovered during the last decades. At the moment it is possible to get reliable results of few of its broadest properties, like magnetic properties. They could give new insights about the physics underlying the strength and features of HBs. In this article we analize the electronic origin of NMR spectroscopic parameters of malonaldehyde, MA, and some substituted MAs. These substituted MAs are such that the H-bond are assisted by one of the two phenomena: resonance assisted, RAHB or charge assisted, CAHB. We have studied the dependence of those parameters with two of the main factors which most contribute to both phenomena, the geometrical and the electronic factors, and found out how can they be used to characterize the RAHB or the CAHB by means of reliable theoretical calculations. We show that, in the set of compounds analized here: i) the shielding of the proton of the H-bond can be used as a measure of the strength of the HB, and ii) the relation between contact and non-contact mechanisms of J-couplings between donor and acceptor atoms is a reliable descriptor of whether the H-bond is resonance assisted or charge assisted.