The Structural Side of Conjugation in Some Stable Primary Enamines and Related Systems

Stable Conjugated Prim ary Enamines, ^-C onjugation , oand .T-Effects in Conjugated Systems The structures of l,6-diam ino-l,6-diphenyl-1.3,5-hexatriene (2) and its l,6-bis(N,N-bistrim ethylsilylam ino)-derivative (3) are com pared. The X-ray crystal structure analyses of 2 and 3 show that turning off the conjugation with the nitrogen lone pairs by orthogonal orientation of the R2N-plane has no m easurable effect on the structural features of the framework of the central planar carbon jr-system. In a rela ted substituent-stabilized prim ary enam ine (4) a slightly elongated C=C bond is found by X-ray diffraction.