The conformation of some di-, tetra-, and hexa-hydropyridazines in the solid state

Abstract

The conformations of five hydropyridazines in the solid state have been determined from their crystal structures. The results are compared with the conformations of these compounds in solution as analysed by interpretation of their ¹H and ¹³C n.m.r. spectra Dihydropyridazine (1) adopts the twist-boat conformation in the solid state however, in accordance with the interpretation of ¹H n.m.r. spectra tetrahydropyridazines, (2) and (3) adopt the half-chair conformation in agreement with that found for (2) and in contrast to that found for (3) in solution. Hexahydropyridazine (4) was found to adopt the chair conformation both in solution and in the solid state.