Lewis-base adducts of Group 11 metal(I) compounds. Part 58. Syntheses, X-ray structures, and far-infrared spectra of the novel [CuX2(bidentate ligand)]–(X = Cl or Br) anion salts of the [Cu(dpa)2]+ cation and the dimeric iodide [(dpa)Cul2Cu(dpa)][dpa = di(2-pyridyl)amine]

Abstract

Reaction of copper(I) halides (CuX, X = Cl, Br, or I) in acetonitrile solution with di(2 pyridyl)amine(dpa) yields 1 : 1.5 adducts with the chloride and bromide, a 1 : 1 adduct with the iodide, and a 1 : 2 adduct with the chloride. The compounds have been characterized by spectroscopic and single-crystal X-ray methods. The 1 : 1 iodide is a dimer, [(dpa)Cul₂Cu(dpa)], of a type familiar with other bidentate nitrogen base ligands, but the l : 1.5 complexes are ionic, formulated as [Cu(dpa)₂]⁺[Cu(dpa)X₂]^–, containing the first structurally characterized [Cu(dpa)₂]⁺ cations and [CuX₂(bidentate ligand)]^– anions, while the 1 : 2 chloride is [Cu(dpa)₂]⁺Cl^–. In the [Cu(dpa)²]⁺ cation mean Cu–N is ca. 2.00 Å, while in the [Cu(dpa)X₂]^– anions Cu–N is ca. 2.05 Å and Cu–Cl and Cu–Br 2.369(2), 2.302(2) and 2.490(6), 2.439(6)Å respectively. The dpa ligand in all cases is essentially planar. The far i.r. spectra of the anions show bands at 214 cm^–1(chloride) and 160 cm^–1(bromide) which can be assigned to the asymmetric stretching mode of the CuX₂ unit.