Ferrocene-Containing Pseudorotaxanes in Crystals: Aromatic Interactions with Hammett Correlation.

Single crystals of pseudorotaxanes, [(FcCH 2 NH 2 CH 2 Ar)(DB24C8)][PF 6 ] (DB24C8 = dibenzo[24]crown-8, Fc = Fe(C 5 H 4 )(C 5 H 5 ), Ar = -C 6 H 3 -3,4-Cl 2 , -C 6 H 3 -3,4-F 2 , -C 6 H 4 -4-F, -C 6 H 4 -4-Cl, -C 6 H 4 -4-Br, -C 6 H 3 -3-F-4-Me, -C 6 H 4 -4-I) and [(FcCH 2 NH 2 CH 2 C 6 H 4 -4-Me)(DB24C8)][Ni(dmit) 2 ] (dmit = 1,3-dithiole-2,4,5-dithiolate), were obtained from solutions containing DB24C8 and ferrocenylmethyl(arylmethyl)ammonium. X-ray crystallographic analyses of the pseudorotaxanes revealed that the aryl ring of the axle moiety and the catechol ring of the macrocyclic component were at close centroid distances and parallel or tilted orientation. The structures with parallel aromatic rings showed correlation of the distances between the centroids to Hammett substituent constants of the aryl groups.