Xanes of the Pd and Pt atoms in square and octahedral chloride complexes

The fine structure near the ionization threshold in metal X-ray L-absorption spectra of the clusters PdCl²⁻₄, PtCl²⁻₄, PdCl²⁻₆ and PtCl²⁻₆ simulating solid complex compounds of the type K₂PdCl₄ and so on has been calculated using the SCF Xα SW method. Pt L₃ absorption spectra for the complexes K₂PtCl₄ and K₂PtCl₆ have been obtained using synchrotron radiation. The pre-edge white line and the near-edge fine structure (XANES) in Pd and Pt spectra of these square and octahedral chloride complexes have been shown to arise, respectively, from electron excitation to a vacant bound molecular orbital (e_g for octahedral and b_1g for square complexes) and from photoelectron resonance elastic scattering by the metal atom and its first coordination sphere. The calculations indicated no intense pre-edge transitions for the metal L₁ spectra of these complexes and the XANES was shown to be due to several intense narrow shape resonances of the t_1u and a_2u, e_u for octahedral and square complexes, respectively.