Coordination behaviour of 1-(4,2':6',4''-terpyridin-4'-yl)ferrocene and 1-(3,2':6',3''-terpyridin-4'-yl)ferrocene: predictable and unpredictable assembly algorithms

The reaction of 1-(4,2':6',4''-terpyridin-4'-yl)ferrocene ( 2 ) with ZnI 2 leads to [{ZnI 2 ( 2 )} 4 . 1.4MeOH . 0.8H 2 O] which contains a discrete [4+4] metallocycle. Crystal growth experiments demonstrate that reactions of 2 with Zn(OAc) 2 or CuCl 2 result in the formation of single- or double-stranded 1D-polymer chains, respectively, the latter facilitated by the formation of {Cu 2 Cl 4 } dinuclear nodes. Whilst both 2 and its isomer 1-(3,2':6',3''-terpyridin-4'-yl)ferrocene ( 3 ) present V-shaped donor sets, rotation about interannular bonds in 3 generates flexible vectorial properties associated with limiting convergent and divergent orientations of the nitrogen donors. The synthesis and characterization of 3 are described as are reactions of 3 with ZnCl 2 or ZnBr 2 which lead, respectively, to a metallosquare in [{ZnCl 2 ( 3 )} 4 . 3CHCl 3 . 3MeOH] or a helical polymer in [{ZnBr 2 ( 3 )} . MeOH] n . The tight pitch of the helix in the latter (8.7879(9) Å) is controlled by a combination of the orientations of the N,N ''-donor sets in 3 , and intra-chain π-stacking interactions involving ferrocenyl and pyridine units.