Electron localization function study on intramolecular electron transfer in the QTTFQ and DBTTFI radical anions

摘要

The unsymmetrical distribution of the unpaired electron in the ground state of the DBTTFI~(?-) radical anion (bi(6-n-butyl-5,7-dioxo-6,7- dihydro-5H-[1,3]dithiolo[4,5-f]isoindole-2-ylidene) is theoretically predicted using the M06-2X/6-31+G(d,p) level of calculations. The results are additionally confirmed by single point calculations at B3LYP/aug-cc-pVTZ, LC-ωPBE/aug-cc-pVTZ, and M06-2X/aug-cc-pVTZ levels. DBTTFI, containing the TTF (tetrathiafulvalene) fragment, may be used in the construction of organic microelectronic devices, similarly to the radical anion of QTTFQ. The unsymmetrical distribution of spin density in (QTTFQ)~(?-) has been confirmed using M06-2X/aug-cc-pVTZ calculations, with subsequent study using topological analysis of electron localization function (ELF). The reorganization of the chemical bonds during intramolecular electron transfer in (QTTFQ) ~(?-) and (DBTTFI)~(?-) has been analyzed using bonding evolution theory (BET). The reaction path has been simulated by the IRC procedure, and the evolution of valence basins has been described using catastrophe theory. The simple mechanisms: (QTTFQ)~(?-): η-1 - 3-CC~+-0: ~(-?)(QTTFQ) and (DBTTFI)~(?-): η-1 - 3-[F]_4[F~+]_4-0: ~(-?)(DBTTFI), each consisting of three steps, have been observed. Two cusp or 4-fold catastrophes occur immediately after the TS. Our study shows that potential future microelectronic devices, constructed on the basis of the (QTTFQ)~(?-) and (DBTTFI)~(?-) systems, should exploit the properties of the C≥C bond.