Conformational behaviour of non-fused biheterocycles. Part 11. 2,2′-Bi-imidazolyl

Abstract

The torsional potential of 2,2′-bi-imidazolyl has been analysed by means of ab-initio computations making use of minimal and split valence basis sets. The most significant geometrical parameters have been optimized, but the potential energy curve is essentially insensitive to geometry optimization. Only minor energy variations are involved in large amplitude motions between cis and perpendicular conformations, transoid-structures being significantly more stable. The general shape of the curve is not modified upon enlarging the basis set, but the relative stabilities of cisoid- and transoid-structures are increased by about 20%.