ISSN:
0947-6539
Keywords:
boron compounds
;
fluxionality
;
iron complexes
;
NMR spectroscopy
;
rearrangements
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The fluxional behavior of [1-4-η4 - exo - 7 - dipropylborylcyclohepta - 1,3,5-triene]tricarbonyliron (14) has been studied by dynamic NMR. The 2 D 1H and 13C EXSY NMR experiments carried out at various temperatures revealed that three independent fluxional processes occur in 14. The fastest rearrangement is a [1,7] B sigmatropic shift accompanied by [1,2] Fe migration (EA = 71.2±2.3 kJ mol-1, ln A = 32±1). Two other rearrangements also take place: [1,3] B sigmatropic and [1,3] Fe haptotropic migrations. The analysis of the observed selectivity towards [1,j] B sigmatropic shifts ([1,3] and [1,7] B shifts are observed, but [1,5] B shifts are not) in terms of theoretical predictions gives reason to assume that the [1,j] boron migrations occur with inversion of configuration at the migrating atom.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19960021122
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