Ferrocene-containing [1]-, [2]-, [3]- and [4]rotaxanes synthesized from a common precursor

The Cu-catalyzed reaction of a dialkylammonium, having ferrocenyl and hexynyl end groups, FcCH 2 NH 2 CH 2 C 6 H 4 -4-O(CH 2 ) 4 C&z.tbd;CH]PF 6 (Fc = Fe(C 5 H 4 )(C 5 H 5 )), with a crown ether having an azidemethyl side-arm yields a [1]rotaxane composed of a single molecule. The crystal structure of the [1]rotaxane suggests an arrangement where the 1,4-phenylene ring is tilted at 22° close to the catechol ring rather than in a parallel alignment. Another dialkylammonium with ferrocenyl and alkynyl terminal groups, [FcCH 2 NH 2 CH 2 C 6 H 4 -4-O(CH 2 ) 4 C&z.tbd;CH]PF 6 , reacts with aromatic compounds with one to three azide groups in the presence of dibenzo[24]crown-8-ether (DB24C8) and [Cu(MeCN) 4 ]PF 6 catalyst, to afford the corresponding [2]-[4]rotaxanes. The products contain DB24C8 molecules as the cyclic components which are bound to the ammonium group of the axle component with NH O hydrogen bonding. The [3]rotaxane having two triazole groups on the axle component reacts with PdCl 2 (MeCN) 2 to yield mono- and di-palladium complexes with different conformations of the axle component. [1]-, [2]-, [3]- and [4]rotaxanes were synthesized by reaction of azide compounds with dialkylammonium with ferrocenyl and alkynyl terminal groups.