High-electron-density C6H6 units: stable ten-pi-electron benzene complexes.
The first stable benzene molecule with ten pi electrons is predicted. Stability is achieved through barium atoms acting as an electron-donating "matrix" to C6H6 in the inverted sandwich complex [Ba2(C6H6)]. The bis(barium)benzene complex has been computed at the density functional level of theory by using the hybrid functional mPW1PW91. Ab initio calculations were performed by using the coupled-cluster expansion, CCSD(T). Nucleus independent chemical shift (NICS) indices imply distinct aromatic character in the benzene ring of bis(barium)benzene. The D6h-symmetric structure with a 1A(1g) electronic ground state represents a thermochemically stable, aromatic benzene molecule with four excess pi electrons, stabilised by two barium ions. A possible molecular wire, built up from Ba end-capped thorium-benzene "sandwiches", is discussed.
Diefenbach
Martin
M
Institute of Chemistry, Technical University Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.martin.diefenbach@mail.chem.tu-berlin.de
Schwarz
Helmut
H