Cyclooctatetraenyl di--propyl borane

The NMR spectra of cyclononatetraenyl(di- -propyl)borane 39 are temperature dependent indicating the occurrence of an intramolecular rearrangement 

The activation parameters for this rearrangement (A// = 58.7 0.8 kJ mol AS = -32 5 J mol K AG (298) = 67.7 0.1 kJ mor ) are close to those for the reversible double bond fluctuations in other monosub-stituted cyclooctatetraenes [40]. It was concluded that the interaction of the empty 2p-AO of boron atom with the cyclic -ir-system of the double bonds in 39 does not notably affect the bond shifting process. 

REARRANGEMENTS IN CYCLONONATETRAENYL-(DI- -PROPYL)BORANE. COMPARISON WITH THE DYNAMIC PROPERTIES OF CYCLONONATETRAENYL(TRIMETHYL)TIN 

1 Synthesis of Cyclononatetraenyl(di-R-propyl)borane 22 and Mechanism of Borotropic Migrations in this Borane. Selection Rules for the Sigmatropic Migrations of Dialkylboryl Groups 

In cyclononatetraenyl(di-H-propyl)borane 22 the [1,3]-B shift is the fastest rearrangement, whereas in the irontricarbonyl complex of cycloheptatrienyl(di- -propyl)borane 38 the [1,7]-B shift is faster than the [ 1,3]-B migration. This observation corresponds to the modified least motion principle, which is recently 

---