Subtle role of counteranions in molecular construction: Structures and properties of novel Cu(II) coordination complexes with bis-(1-benzoimidazolymethylene)-(2,5-thiadiazoly)-disulfide

The direct self-assembly of bis-(1-benzoimidazolymethylene)-(2,5-thiadiazoly)-disulfide (L) with CuSO4, Cu(NO3)2 and CuCl2 affords three novel supramolecular complexes: 1-D ladder-like chain complex {[Cu(SO4)(L)] · (CH3OH)}n (1), dimer complexes {[Cu(L)(CH3O)]2(NO3)2} · 2H2O (2) and [Cu(L)(Cl)(N3)]2 · 2CH3OH (3). The nature of the anions is the underlying reason behind the differences in the structures of this series of complexes. Furthermore, utilizing the coordinatively unsaturated complexes 2 and 3 as precursor complexes, two new derivative complexes [Cu(L)(NCS)(CH3O)]2 · 2CH3OH (2A) and [Cu(L)(ClO4)(N3)]2 · 2CH3OH (3A) are obtained by the addition and exchange reactions of complexes 2 and 3 with anions. X-ray crystallographic analysis shows that the two derivatives retain the skeletons of their precursor complexes, and the anions with the stronger coordination capacity only bind to the active position of precursor complexes. In addition, different from the obvious effects on the structures in the direct self-assembly of the metal and ligand, the change of counteranions has no great impact on the structures in the anion exchange reactions. We also study the catalytic activities of the complexes 2, 2A, 3, and 3A, which have similar skeletons, for the oxidative coupling polymerization of 2,6-dimethylphenol (DMP). And we find that the introductions of different coordination counterions produce significant impacts on the catalytic properties of these complexes.