Exploring the concept of aromaticity on complexes of a fourfold benzannulated cyclopentadienyl ligand.
The ligand dibenzo[c,g]fluorenide (Dbf(-)), combines a cyclopentadienide ligand and 1,1'-binaphthyl fragment in one molecule. Preliminary investigations confirmed the special electronic situation in this 6pi-electron donor by way of a series of novel transition-metal complexes. Herein, the electron delocalization was investigated in detail by means of DFT calculations in combination with calculations on the nucleus-independent chemical shifts (NICS). These results clearly prove that the Dbf(-) ion gains the largest aromatic stabilization among all benzannulated fluorenides, and there are two almost olefinic C=C bonds in this structure. These bonds undergo cyclopropanation when treated with ZnEt(2) and ClCH(2)I in a modified Simmons-Smith reaction.
Pammer
Frank
F
Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse Geb. 54, 67663 Kaiserslautern, Germany.
Sun
Yu
Y
Weismann
Daniel
D
Sitzmann
Helmut
H
Thiel
Werner R
WR