Dibenzo[c,g]fluorene: The Combination of Cyclopentadiene

and 1,1’-Binaphthyl in one Ligand

F. Pammer, Y. Sun, W. R. Thiel

Fachbereich Chemie, TU Kaiserslautern, Erwin-Schrödinger Str., Geb. 54, 67663 Kaiserslautern, Germany


The discovery of ferrocene in 1951 is one of the central milestones in organometallic chemistry1. During the last 60 years a multitude of cyclopentadienide (Cp -1) compounds have been synthesized and characterized.

We recently reported the synthesis of the first transition metal complexes of dibenzo[c,g]fluorenide (Dbf-1)2, an h5 -coordinating Cp -1 analogue ligand enclosing a 2,2’-bridged 1,1’-binaphthyl system. It therefore possesses axial chirality with the axis of chirality included in the Cp fragment (Figure 1), although its barrier of racemisation is low. Due to its chemical reactivity, its spectroscopic features and due to DFT calculations, the electronic structure of the anion Dbf-1 is more related to cyclopentadienide than to fluorenide. These results will be summarized in the presentation.

1.- a) T. J. Kealy, P. L. Paulson, Nature 1951, 168, 1039-1040; b) E. O. Fischer, W. Pfab, Z. Naturforsch. 1952 , 7b, 377-379; c) S. A. Miller, J. A.; Tebboth, J. F. Tremaine, J. Chem. Soc. 1952, 632-635.

2.- a) F. Pammer, Y. Sun, C. May, G. Wolmershäuser, H. Kelm, H.-J. Krüger, W. R. Thiel, Angew. Chem. Int. Ed. 2007, 46, 1270-1273. b) F. Pammer, Y. Sun, W. R. Thiel, Organometallics 2008, 27, 1015-1018. c) F. Pammer, Y. Sun, M. Pagels, D. Weismann, H. Sitzmann, W. R. Thiel, Angew. Chem. Int. Ed. 2008, 47, 3271-3274. d) F. Pammer, Y. Sun, D. Weismann, H. Sitzmann, W. R. Thiel, Chem. Eur. J. 2010, 16, 1265-1270. e) F. Pammer, Y. Sun, M. Sieger, J. Fiedler, B. Sarkar, W. R. Thiel, Organometallics 2010, 29, 6165-6168.