Copper co-ordination to thioether ligands. Spectroscopic studies of dimeric copper(II) complexes of 2-(3,3-dimethyl-2-thiabutyl)pyridine and the crystal structure of di-µ-bromo-bis{bromo[2-(3,3-dimethyl-2-thiabutyl)pyridine-NS]copper(II)}

Abstract

Dimeric complexes of the type [(CuLX₂)₂][X = Cl or Br, L = 2-(3,3-dimethyl-2-thiabutyl)pyridine] have been prepared and characterised by electronic, electron spin resonance, and far-i.r. spectroscopy. The structure of [(CuLBr₂)₂] has been determined by single-crystal X-ray diffraction techniques, from diffractometer data. Crystals are Triclinic, space group P, with a= 9.040(1), b= 13.100(2), c= 15.455(2)Å, α= 120.26(1), β= 92.80(1), γ= 111.31(1)°, and Z= 2. After full-matrix least-squares refinement, the final R value was 0.079 for 3 070 observed data. The complex consists of discrete, non-centrosymmetric, dibromo-bridged dimers. The co-ordination geometry of each copper(II) centre is distorted square pyramidal. A chelated ligand L [mean Cu–S = 2.352(6), Cu–N = 2.06(2)Å] and two bromide ions [mean Cu–Br = 2.372(3) and 2.415(3)Å] form the tetrahedrally distorted basal plane of each square pyramid, with a longer [mean 2.902(4)Å] apical Cu–Br bridging bond. The tetrahedral distortions are attributed to steric effects.