Pentafoil knot 2 is
isolated and used with a chloride anion bound in the central
cavity. The Star of David [2]catenane 3 was treated with
Na4EDTA to generate the demetalated link 4.
Reagents and conditions:
(a) FeCl2, dimethyl sulfoxide, 60 °C, 24 h followed
by excess saturated aqueous KPF6 solution; (b) Hoveyda-Grubbs
second-generation catalyst (H2IMes)Cl2RuCH(o-OiPrC6H4), 1,2-dichloroethane/MeNO2 (1:1), 60 °C, 24 h followed
by excess saturated aqueous KPF6 solution; (c) FeSO4·7H2O, ethylene glycol, 170 °C, 24 h
followed by excess saturated KPF6 in methanol; (d) Na4EDTA (EDTA = ethylenediaminetetraacetic acid), H2O/MeCN (1:1), 80 °C, 4 h.