Visible absorption spectra of copper-ethylene-diamine-bis(acetylacetone) in the crystalline State

For square planar copper complexes the crystal field theory predicts a splitting of the five-fold degenerate d-orbital energy-levels into four energetically different levels, d <SUB>xy</SUB>, d<SUB> z</SUB> <SUP>2</SUP>, d <SUB>x</SUB> <SUP>2</SUP>-y <SUP>2</SUP>, and d <SUB>zx</SUB>(d <SUB>yz</SUB>), in the order of diminishing energy<SUP>1</SUP>. The visible absorption in these systems is associated with the transitions from d <SUB>Zx</SUB> to d<SUB> xy</SUB> (w <SUB>1</SUB>, from d <SUB>x</SUB> <SUP>2</SUP>-y <SUP>2</SUP> to d xy (w <SUB>2</SUB>)and from d <SUB>z</SUB> <SUP>2</SUP>to d<SUB>xy</SUB> (w <SUB>3</SUB>), where w <SUB>1</SUB> is the shortest wave-length and w <SUB>3</SUB> the longest wave-length band with w <SUB>2</SUB> in between. The absorption spectra of square planar copper complexes in solution invariably consist of one broad absorption band in the visible region, which, however, could be resolved into three component bands by Gaussian analysis<SUB>2</SUB>. With the object of finding if these split levels could be detected in the absorption spectra of the single crystal of a square planar copper complex, the present investigation was undertaken on the absorption spectra of an elongated platelet of copper-ethylene-diamine-bis(acetylacetone)