Syntheses and Crystal Structures of Mercury(II) and Copper(II) Complexes of an 18-Membered NS4-Macrocycle

An 18-membered NS4-macrocycle was employed, and its complexation behaviors with hard and soft metal ions were investigated. Reactions of L with mercury(II) nitrate and thiocyanate afforded endocyclic mononuclear complexes [Hg(L)(NO3)(2)] (1) and [Hg(L)(SCN)(2)] (2), respectively, with anion coordinations. In the nitrato complex 1, the mercury(II) center is six-coordinate, being bound to three S donors and one pyridine N atom in L, and the coordination sphere is completed by two monodentate nitrate ions from both sides of the macrocyclic plane adopting a distorted octahedral geometry. The thiocyanato complex 2, which contains two crystallographically independent but almost isostructural complex units is five-coordinate, being bound to NS2 donors in L and two monodentate thiocyanate ions on the same side of the bound macrocycle unlike 1, adopting a distorted square pyramidal geometry. Reaction of L with CuCl2 center dot 2H(2)O yielded a dark-green bis(macrocycle) trinuclear complex, [Cu-3(L)(2)Cl-6]center dot 0.5CH(2)Cl(2) (3), in which two endocyclic monocopper (II) complex units are linked by an exocyclic one Cu and two bridging Cl atoms. In 3, interestingly, the local coordination environments of the three copper(II) atoms are different, with four, five, or six coordination, adopting a distorted square pyramidal, tetrahedral, or octahedral geometry, respectively. From these results, it is found that the ditopic ligand L reacts with both soft and hard metal-ion species to give diverse types of endocyclic complexes whose structures are also dependent on the anions used.