Crystal structure and electronic properties of ammine[tris(2-aminoethyl)amine]copper(II) diperchlorate and potassium penta-amminecopper(II) tris(hexafluorophosphate)

Abstract

The crystal structure of the title compounds [Cu(tren)(NH₃)][ClO₄]₂(1) and K[Cu(NH₃)₅][PF₆]₃(2) have been determined by X-ray diffraction methods using three-dimensional diffractometer data; the structures were solved by heavy-atom techniques and successive Fourier synthesis. Compound (1) crystallises in a cubic unit cell, space group P2₁3, with dimensions a= 11.626(3)Å and Z= 4, and (2) crystallises in the orthorhombic unit cell, space group Imma with dimensions, a= 14.90(1), b= 11.79(1), c= 10.57(1)Å, and Z= 4. The cation in (1) has a trigonal-bipyramidal molecular structure with strict C₃ symmetry while that in (2) has a square-based pyramidal molecular structure with strict C_2v symmetry. The polycrystalline and single-crystal electronic properties for these two σ-bonding CuN₅ chromophores are reported and related to the one-electron energy levels for the two stereochemistries, using extended-Hückel molecular-orbital calculations, and correlated with earlier data on high-symmetry five-co-ordinate CuN₅ chromophores.