Resonance assisted hydrogen bonds in open-chain and cyclic structures of malonaldehyde enol: A theoretical study

In 1989 Gilli, Bellucci, Ferretti and Bertolasi introduced the notion of Resonance Assisted Hydrogen Bonding (RAHB) one of the most fruitful concepts in structural chemistry. After reviewing our previous contributions to this topic, the present work analyzes theoretically this concept especially in non-cyclic structures. Geometries, electron densities and Laplacian at the bond critical points, cooperativity through many body interaction energies, deformation energies as well as NMR properties (chemical shifts and 2hJOO coupling constants) are used for the discussion.