Palladiu(II,IV) Mixed-valence Complexes of 1,2-Diaminoethane, 1,3-Diaminopropane, and Diethylenetriamine: Syntheses, Electronic, Infrared, Raman, and Resonance Raman Spectra and X-Ray Studies

Article abstract of DOI:10.1039/DT9850000815

The syntheses of the neutral, linear-chain mixed-valence complexes 2>4>, 2>4>, 2>4>, and a mixed-valence complex of empirical formula Pd₂(en)₂Br₃Cl₃, where en=1,2-diaminoethane and tn=1,3-diaminopropane, are reported, together with their electronic, infrared, Raman, and resonance Raman spectra.In addition, the synthesis and spectroscopic properties of the first palladium complex of the +1 charge type, 3>Br₂, where dien=diethylenetriamine, is reported.The electronic spectra of the complexes are characterised by intense, broad intervalence bands which decrease in wavenumber in the order Cl > Br.The resonance Raman spectra show overtone progressions (v₁ν₁) in the axial X-Pd^IV-X symmetric stretching mode (ν₁), which lies at ca. 260 cm^-1 for X=Cl and at ca. 145 cm^-1 for X=Br, and combination tones v₁ν₁ + ν_n, where ν_n is the ν(Pd-X) equatorial stretching mode, or ν₂, ν_asym(X-Pd^IV-X), the antisymmetric chain-stretching mode.The excitation profiles of the ν₁ and 2ν₁ bands of the neutral chain complexes do not reach maxima even with excitation of the lowest available wavenumber (12510 cm^-1).These complexes appear to be more delocalised than those of the +2 charge type.Powder diffraction data indicate that Pd₂(en)₂Br₃Cl₃ and 2>4> are isostructural and belong to space group Ama2.

Full text of DOI:10.1039/DT9850000815

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