Structures of Quino[7,8‐<i>h</i>]quinoline and Quino[8,7‐<i>h</i>]quinoline

Abstract

The two title compounds 1 and 2 are almost planar in the crystalline state. The decades-old uncertainties concerning the synthesis and structural assignment have now been resolved by X-ray structure analyses of the two compounds. A striking feature in the case of the extremely strongly and also kinetically active base 1 is the large central external angle of the “naphthalene unit” (125.4°), which results in a relatively large N ⃛N distance of 272.8 pm.