N-苄叉基-1-氨基-萘及其类似物的构象与分子扭曲的共轭 驱动力

确定了N-[(4-二甲基氨基)-苄叉基]-2-氨基苯并咪唑(1)，N-[(4-二甲基氨基)-苄叉基]-2-氨基苯并噻唑(2)和N-苄叉基-1-氨基-萘(3)的晶体结构。利用AM1，RHF，DFT方法和STO-3G,4-31G,6-311G及6-311G基组，优化每个分子的23个扭曲构象(θ=0°～-89°)。尽管不同方法得到的最优构象的扭角不同，分子扭曲的驱动力总是起因于电子作用，在任一分子、任何电子态中，离域的π体系总是失稳定的，全平面构象不是π体系最稳定的构象。π电子的离域是分子扭曲的驱动力之一，与经典观点相反，非键原子间的核排斥作用是分子扭曲的阻力，而不是动力。

The Conformation of N- (phenylmethylene)-2-Naphthaleneamine-Like Species and the π-Driving Force for Distorting Geometry

The crystal structures of N-{[4-(dimethylamino)phenyl] methylene}-2- benzoimidazoleamine(1), N-{[4-(dimethylamino) phenyl]methylene}-2- benzothiazoleamine (2) and N-(phenylmethylene)-2-naphthaleneamine (3) were determined. Twenty-three rotational eometries (θ=0°～-89°) of each of the molecules were optimized using AM1, RHF/STO-3G, 4-31G, 6- 311G, 6-311G and B3LYP/4-31G, 6-311G, 6-311G. The torsional angles of the preferential geometries of compound 1, 2 and 3 are close to the experimental values (1, θ=-10.69°; 2, θ=-11.99°; 3, θ=-52.88°) in the case of any optimized method. Although different optimized methods provide a specific molecule with different preferential geometries, the electron interaction always favors a twisted geometry and the nuclear repulsion is, practically, a resistance for distortion of th emolecule, which is not an artifact of a specific optimized method. The π system in the geometry with θ=0° is most destabilized no matter whether it is delocalized or not. It appears that the π system always prefers a twisted geometry.