15N-CIDNP measurements and ab initio calculations on the nitration of dithieno[3,4-b:3′,4′-d]pyridine N-oxide

Abstract

¹⁵ N NMR studies indicate that radical ion coupling is involved in the nitration of the title compound. During the reaction under mildly acidic conditions at 40°C strong emission signals appear, while at 0°C signal enhancement is observed. Orientation effects of the ring system under mildly and strongly acidic conditions have been investigated by means of ab initio RHF/3-21G(*) and ROHF/3-21G(*) calculations.