pi-H...O hydrogen bonds: multicenter covalent pi-H interaction acts as the proton-donating system.

The MP2 method and the Pople-style basis sets 6-311++G(d,p), 6-311++G(2df,2pd), and 6-311++G(3df,3pd) were used to perform calculations on H3O+...

Hydrogen bonds with pi and sigma electrons as the multicenter proton acceptors: high level ab initio calculations.

Pi-electrons of acetylene and sigma-electrons of molecular hydrogen were investigated as Lewis bases in different complexes. Hence high level ab initio calculations were performed up to the MP2/6-311++G(3df,3pd) level of approximation. It was found that species analyzed possess characteristics typical for H-bonded systems.

Intramolecular H-bonds: DFT and QTAIM studies on 3-(aminomethylene)pyran-2,4-dione and its derivatives.

Intramolecular N-H...