Tetra- and Pentacyclopropylcyclopentadiene—Two New Donor-Substituted Ligands for Metal Complexes Small Ring Building Blocks in Organic Synthesis: Part 74. This work was supported by the Fonds der Chemischen Industrie as well as the companies BASF AG and Chemetall GmbH (Chemicals). The authors are indebted to Prof. Burkhard König, Regensburg (Germany) and Prof. Pierre H. Dixneuf, Rennes (France), for measuring the oxidation potentials of the new ferrocenes, as well as to Dr. Burkhard Knieriem, Göttingen, for his careful proofreading of the final manuscript. Part 73: H. Nüske, M. Noltemeyer, A. de Meijere, Angew. Chem. 2001, 3509–3511; Angew. Chem. Int. Ed. 2001, 40, 3411–3413. Part 72: A. de Meijere, M. von Seebach, S. I. Kozhushkov, S. Cicchi, T. Dimoulas, A. Brandi, Eur. J. Org. Chem. 2001, 3789–3795.