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Restricted Rotation of an Unsubstituted η 5 ‐Cyclopentadienyl Group in Solution Demonstrated by 13 C NMR Spectroscopy
Author(s) -
Mynott Richard,
Lehmkuhl Herbert,
Kreuzer EvaMaria,
Joussen Eckhard
Publication year - 1990
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199002891
Subject(s) - steric effects , chemistry , cyclopentadienyl complex , ethylene , carbon 13 nmr , ligand (biochemistry) , nuclear magnetic resonance spectroscopy , nmr spectra database , styrene , ring (chemistry) , crystallography , carbon 13 nmr satellite , rotation (mathematics) , spectroscopy , spectral line , stereochemistry , fluorine 19 nmr , organic chemistry , physics , copolymer , receptor , biochemistry , polymer , geometry , mathematics , astronomy , catalysis , quantum mechanics
The barrier ΔG ≠ for the rotation of the Cp ring in 1 has been estimated from 13 C‐NMR spectra to be 34.2 ± 1.5 kJmol −1 at −90 °C. The other sterically very bulky ligands may be the reason for the rotation about the CpM bond in 1 and 2 being so strongly hindered that it is slow on the NMR time scale below ca. −100 °C. When the styrene ligand in 1 is replaced by an ethylene ligand the Cp‐ 13 C‐NMR signal does not change significantly up to −95 °C.