X-ray absorption spectral investigations on mixed-valence copper complexes of penicillamine and cysteamine

The X-ray K-absorption spectra of copper in some of its complexes involving ligands like penicillamine (known detoxicating agent for heavy metal poisoning) and cysteamine (a known radiation protector) have been investigated using a 40 cm curved crystal spectograph. These complexes are described in the literature as being mixed-valence 1, 2]. The copper-penicillamine complex shows two distinct edges, K₁ and K₂, indicating mixed-valency in the complex. The cysteamine complexes do not show any splitting of the edges. In one of the cysteamine complexes, which is said to involve molecular oxygen, the magnitudes of shifts of the main edge and principal absorption maximum fall close to copper (II) compounds whereas in the other complex, these shifts are in the range of copper (I) compounds. The probable reasons for the observed deviations have been discussed.