Identification and characterization of 1,2-BN cyclohexene using microwave spectroscopy

Abstract

1,2-BN cyclohexene has been produced from 1,2-BN cyclohexane through the loss of H 2 and characterized and identified using a pulsed-beam Fourier-transform microwave spectrometer. Microwave spectra were measured in the frequency range of 5.5-12.5 GHz, providing accurate rotational constants and quadrupole coupling strengths. Results of high level calculations allowed clear assignment ofthe spectra to1,2-BN Cyclohexene. Heating the initial compound, 1,2-BN Cyclohexane, to 60°C in a 1 atm. neon stream results in the loss of H 2 and conversion to 1,2-BN Cyclohexene and this appears to be the first characterization of this compound as the 1,2-BN Cyclohexene monomer.

Six-Membered Rings With Two or More Heteroatoms With at Least One Boron

“…53 The gas phase microwave spectroscopy was applied for the identification and the first characterization of 1,2-BN cyclohexene which was produced from 1,2-BN cyclohexane through the loss of H 2 (i.e., heating sample in a Ne gas stream prior to insertion into microwave cavity) (Scheme 1). 54 This work presented the opportunity to compare the rotational constants and quadrupole coupling strengths for 1,2-BN cyclohexene with the aromatic, planar 1,2-dihydro-1,2-azaborine. The high level calculations were also applied to estimate structural Fig.…”

Kinetics of −CH2CH2– Hydrogen Release from a BN-cyclohexene Derivative

“…On the other hand, prior to this work, a complementary kinetic analysis of dehydrogenation from the carbonaceous components of these CBN heterocycles remained elusive in our hands due to the lack of effective reaction conditions for this transformation. We had found that, at the elevated temperatures typically required for cycloalkane dehydrogenation, rapid BN hydrogen release occurs first to produce species that are isostructural and isoelectronic with cyclohexenes ( A ; Figure , top) . For all-carbon compounds, it is known that dehydrogenation of a cycloalkene is significantly more facile than that of the corresponding fully saturated cycloalkane.…”