title: How big is a Cp? Novel cycloheptatrienyl zirconium complexes with tri-, tetra- and pentasubstituted cyclopentadienyl ligands.
abstract: The new bulky cyclopentadienyl anions 1,2,4-tri(cyclopentyl)cyclopentadienide and 2,3-diisopropyl-1,4-dimethyl-5-trimethylsilyl-cyclopentadienide were prepared. These and the already known 1,2,4-tri(cyclohexyl)-, 1,2,4-tri(isopropyl)-, 2,3-diisopropyl-1,4-dimethyl-, 1,3,4-triisopropyl-2,5-dimethyl-, pentaphenyl-, and p-butylphenyl-tetraphenyl-cyclopentadienide as well as tert-butylindenide were coordinated to the cycloheptatrienylzirconium fragment [(CHT)ZrCl(tmeda)]. The nine zirconium complexes of the [(CHT)Zr(Cp)] type were characterized by elemental analysis and NMR spectroscopy. For five of the sandwich complexes X-ray crystal structure determination could be carried out; structures of the four others were obtained by DFT calculations. The data serve as a basis for cone angle measurements of cyclopentadienyl ligands to evaluate the steric demand of these ligands.
authors.affiliation: Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schroedinger Strasse, 67663 Kaiserslautern, Germany. sitzmann@chemie.uni-kl.de.
authors.forename: Heiko
authors.initials: H
authors.lastname: Bauer
authors.forename: Andreas
authors.initials: A
authors.lastname: Glöckner
authors.forename: Alain C
authors.initials: AC
authors.lastname: Tagne Kuate
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schäfer
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.forename: Matthias
authors.initials: M
authors.lastname: Freytag
authors.forename: Matthias
authors.initials: M
authors.lastname: Tamm
authors.forename: Marc D
authors.initials: MD
authors.lastname: Walter
authors.forename: Helmut
authors.initials: H
authors.lastname: Sitzmann