Microwave spectra of [ 13C] and [ 15N] pyridine N-oxides and a preliminary ring structure

Abstract

Pyridine N-oxide and the four ring substituted pyridine N-oxides were prepared. The microwave spectrum of the parent species was reinvestigated to high J-values ( J max = 40) and centrifugal distortion constants determined. The microwave spectra of the four isotopic species were investigated, and selected lines were measured and corrected for centrifugal distortion. A preliminary substitution structure of the ring is derived and compared to the ring structure in pyridine. Significant differences were found in the CNC part of the ring, whereas C(3)C(4)C(5) is almost unaffected by the N-oxide formation.