The fluxional behavior of [1-4-η4-exo-7-dipropylborylcyclohepta- 1,3,5-triene]tricarbonyliron (14) has been studied by dynamic NMR. The 2D 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 (E(A) = 71.2 ± 2.3 kJ mol-1, In 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.
|Number of pages||6|
|Journal||Angewandte Chemie - International Edition in English|
|Publication status||Published - 1996 Dec 1|
- NMR spectroscopy
- boron compounds
- iron complexes
ASJC Scopus subject areas