Endo- and Exocyclic Coordination of a 20-Membered N2O2S2-Macrocycle and Cascade Complexation of a 40-Membered N4O4S4-Macrocycle.

A 20-membered N2O2S2-macrocycle (L1) and a 40-membered N4O4S4-macrocycle (L2) were employed as a [1:1] and a [2:2] cyclization product, respectively, for the preparation of diverse types of supramolecular complexes including a cascade complex. Six complexes (1-6) of the smaller macrocycle L1 including discrete to continuous forms, mono- to heteronuclear, and endo- to exo- and endo/exocoordination were prepared and their coordination modes were discussed systemically. First, the reaction of L1 with CuI in the presence of trifluoroacetic acid afforded an exocyclic 1-D coordination polymer {[(μ4-Cu4I4)(HL1)2](CF3COO)2} n (1). Meanwhile, the reaction of L1 with Cu(ClO4)2·6H2O afforded a typical endocyclic mononuclear complex [CuII(L1)](ClO4)2·H2O (2). In the reactions of L1 with CdX2 (X = Br and I), isostructural sandwich-type complexes [Cd(L1)2Br2] (3) and [Cd(L1)2I2] (4) were isolated. The treatment of L1 with Hg(ClO4)2 also afforded a sandwich-type complex [Hg(L1)2](ClO4)2 (5). One-pot reaction of L1 with a mixture of HgI2 and CdI2 afforded a dumbbell-type heteronuclear complex {[Cd(L1)]2(μ-Hg2I6)}[Hg2I6] (6), in which the Cd(II) ion occupies the macrocyclic cavity. Further, such two endocyclic Cd(II) complex units are bridged by a square-type (μ-Hg2I6)2- cluster remaining another same cluster separately. The comparative NMR data exhibited a higher affinity of Cd(II) over Hg(II) toward L1, in the parallel to the situation occurred in the solid state. Meanwhile, complexations of the extra-large macrocycle L2 is more challenging to afford some interesting dimercury(II) coordination products including a cascade complex. In solution, the dimercury(II) perchlorato complex of L2 as a metalloligand shows a preferential binding of dabco (1,4-diazabicyclo[2,2,2]octane), but its dimercury(II) iodo complex has a much smaller affinity for dabco. In order to explain these results, the solid dimercury(II) complexes with different anions [Hg2(L2)X4] (7: X = I, 8: X = ClO4) were prepared and characterized. Further, the dimercury(II) perchlorato complex 8 reacts with dabco to forms a cascade complex [Hg2(L2)(μ-dabco)(ClO4)2](ClO4)2·2DMF·2ether (9), exhibiting its formation being metal-driven and coordinated anion-regulated. The observed cascade complexation both in solution and solid states is an example of the adaptive guest binding.