Reactions of NNN′N′-tetra-alkylethylenediamines with copper(II)halides and the crystal structure of bis(NNN′N′-tetraethylethylenediammonium) hexa-µ-chloro-µ4-oxo-tetra[chlorocuprate(II)]

Abstract

Controlled addition of NNN′N′-tetraethylethylenediamine (teed) or NNN′N′-tetramethylethylenediamine(tmed) to concentrated ethanolic solutions of copper(II) chloride produce a series of colour changes and allow isolation of the following compounds: (I) yellow [teedH₂²⁺][CuCl₄^2–], (II) garnet red [teedH₂²⁺]²⁺[Cu₄OCl₁₀^4–], (III) CuCl₂(teed), (IV) yellow [tmedH₂²⁺][CuCl₄^2–], (V) CuCl₂(tmed), and (VI) an ill-defined red product. With copper bromide solution and teed the products were (VII) dark purple [teedH₂²⁺][CuBr₄^2–], (VIII) pale violet [teedH⁺][CuBr₃^–], and (IX) CuBr₂(teed).

On heating the solids or ethanolic solutions of them, compounds (III) and (IX) gave the compounds (NNN′-triethylethylenediamine)CuX₂(X = Cl or Br), with evolution of acetaldehyde.

A three-dimensional crystal structure analysis on compound (II) has been carried out. Full-matrix least-squares refinement on 1478 diffractometer observations gave R 0·06. In a monoclinic unit cell having a= 14·46(2), b= 15·23(2), c= 17·59(2)Å, β= 104·55(3)°, and space group C2/c, Z= 4. The [Cu₄OCl₁₀^4–] ion is tetrahedral with two bridging chlorines and the oxygen atom lying on the crystallographic two-fold axis. The copper atoms have trigonal bipyramidal environments, surrounded by four chlorines and one oxygen at mean distances Cu–Cl-(bridge) 2·40, Cu–Cl(terminal) 2·24, and Cu–O 1·92 Å. The quaternary nitrogen atoms are hydrogen-bonded to terminal chlorine atoms, N⋯Cl 3·14 and 3·17 Å.