Synthesis and crystal structures of novel copper(I) co-ordination polymers and a hexacopper(I) cluster of quinoline-2-thione

Abstract

Quinoline-2-thione (C₉H₇NS) reacted with [Cu(MeCN)₄]⁺ in tetrahydrofuran to give infinite-chain copper(I) complexes [{[Cu(C₉H₇NS)₂]X}_∞](X = ClO₄1 or PO₂F₂2) and [Cu₆(C₉H₆NS)₆]3. The crystal structures of all three have been determined. Complexes 1 and 2 are isomorphous and crystallize in space group P4₂/m, Z= 8 with a= 16.697(1), c= 6.438(2)Å, and a= 16.713(5), c= 6.412(2)Å, respectively. Only the thione sulfur is involved in co-ordination to copper(I), in a bridging mode. Each copper has a distorted-tetrahedral geometry, resulting in an infinite linear-chain framework of (CuS₂)_∞. Two types of chain–chain interactions exist, leading to a three-dimensional structure; stacking of the planar thione between the nearest neighbours with distances of 3.219(1) and 3.206(1)Å for 1 and 2, respectively; hydrogen bonding between the counter anion X and the NH parts of the thione bridges the two ligands, and the neighbouring chains are linked. The visible spectra of the solids exhibited are different from those in solution, and are characteristic of the former. Complex 3 crystallizes in space group P, with a= 13.524(3), b= 13.547(2), c= 8.2106(9)Å, α= 99.18(1), β= 101.01(1), γ= 118.26(1) and Z= 2. The copper core is a distorted octahedron, each copper having a trigonal geometry with two thionate sulfurs and a nitrogen donor from a µ₃-thionate ligand. With the quinoline-2-thione ligand, the polymeric complex is preferred to the hexanuclear complex.