Binuclear copper(I) complexes of a 24-membered macrocycle (L1) derived from 2,5-diformylthiophene and 3-thiapentane-1,5-diamine. Crystal and molecular structure of [Cu2L1(NCS)][ClO4]; a unique example of a single end-to-end bridging thiocyanate between copper(I) atoms

Abstract

2,5- Diformylthiophene and 3-thiapentane-1,5-diamine in a metal-free non-template synthesis react to form a macrocycle L¹. A series of dicopper(I) complexes of L¹ have been prepared by reaction of copper salts with the macrocycle. Bridged complexes were isolated by adding an alkali-metal halide or pseudohalide to the reaction mixture. The dicopper(I) complexes were found to be remarkably stable, being unreactive towards both O₂ and CO. The crystal structure of one complex, [Cu₂L¹(NCS)][ClO₄], has been determined. Crystals are triclinic, space group P, with a= 9.735(8), b= 11.967(9), c= 13.859(11)Å, α= 76.0(1), β= 104.4(1), γ= 98.7(1)°, and Z= 2.2 024 Independent reflections above background were measured on a diffractometer and the structure refined to R 0.072. The two copper ions are bridged by a thiocyanate ion in an end-to-end 1,3-bridging mode. In addition each metal atom is bonded to two imine nitrogens and one thioether sulphur of the macrocycle and have very distorted tetrahedral environments.