Polarized electronic absorption spectra of (ethylenediamine)dichloropalladium(II)

Optical absorption spectra of single crystals of Pd(en)Cl/sub 2/ are reported for temperatures of 300 and 5/sup 0/K from 18,000 to 34,000 cm/sup -1/. Spectra were recorded for linearly polarized light with the electric vector parallel to the molecular twofold symmetry axis (b) and parallel to the stacking of the nearly planar molecules (c). In contrast to the corresponding platinum compound, Pt(en)Cl/sub 2/, the spectra of the Pd(en)Cl/sub 2/ showed no intensity enhancement whatsoever in the stacking direction of the molecules. Also, there was no evidence in the palladium compound for the intermolecular electron-transfer transitions to ionic states that were observed for the platinum compound. The Pd(en)Cl/sub 2/ crystal spectra in the measured region were comprised primarily of ligand field bands. Shifts of d-d transition energies from the resolved bands in aqueous solution were determined to be similar to the shifts observed for PtCl/sub 4//sup 2 -/ in Magnus' green salt, (Pt(NH/sub 3/)/sub 4/)(PtCl/sub 4/).