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η 4 ‐Complexes of 4,7‐Dihydroacepentalene: Facile Degenerate Haptotropic Rearrangement of (η 5 ‐Cyclopentadienyl)(η 4 ‐4,7‐dihydroacepentalene)cobalt(I) in Contrast to its Tricarbonyliron Counterpart
Author(s) -
Schröder Günter,
Butenschön Holger,
Boese Roland,
Lendvai Tomas,
Meijere Armin De
Publication year - 1991
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19911241108
Subject(s) - chemistry , cyclopentadienyl complex , ligand (biochemistry) , cobalt , stereochemistry , crystallography , crystal structure , cyclooctatetraene , derivative (finance) , ring (chemistry) , cyclobutadiene , medicinal chemistry , molecule , inorganic chemistry , organic chemistry , receptor , financial economics , economics , catalysis , biochemistry
The (cyclopentadienyl)cobalt(I) complex 4 of the 4,7‐dihydroacepentalene The numbering of the ring system corresponds to the tricyclo‐decatetraene nomenclature used in the Exp. Part. Thus, 4,7‐substitution would be 2a,4a‐substitution in acepentalene numbering. derivative 2b has been prepared by the reaction of the ligand with (cyclopentadienyl)bis(ethene)cobalt(I). NOE experiments indicate a complexation at the convex face of the polyolefinic ligand. 1 H‐NMR spectra establish a degenerate haptotropic rearrangement with CpCo migration from one diene unit to the adjacent one. The activation energy of this process is estimated to be 15 kcal/mol. An X‐ray crystal structure determination of (η 4 ‐4,7‐dihydroacepentalene)tricarbonyliron derivative 3a shows a distorted coordination of Fe(CO) 3 at the convex face of the ligand, too.