Quantum chemical calculation of aminosubstituted but-2-yne dications: Distonic and gitonic character?

摘要

The tetrakis-dimethylamino substituted but-2-yne dication 1 and related model cations are investigated by DFT, MP2, CCSD and CCSD(T)) quantum chemical calculations to elucidate structural and electronic details, energy barriers and conformational preferences in order to rationalize experimental NMR-spectra and crystallographic structural data of tetrafluoroborate and tetraphenylborate salts of 1. Very small energy differences (<2 kJ mol~(-1)) between different conformations are caused by electronic and steric effects in the cation. In addition, solid-state effects such as anion cation interactions may lead to conformational differences in the salts. In dication 1 and analogous model cations, the distonic arrangement of the charges is preferred over a gitonic configuration.