Resonance Raman spectra of the polynuclear complexes ruthenium red, ruthenium brown, and the related 1,2-diaminoethane substituted complexes

Abstract

The resonance Raman spectra of salts of ruthenium red, [Ru₃O₂(NH₃)₁₄]⁶⁺, and ruthenium brown, [Ru₃O₂(NH₃)₁₄]⁷⁺, in their normal, ²H-, ¹⁵N-, and ¹⁸O-substituted forms have been measured using excitation in the 417–647 nm range. Similar measurements were carried out for the 1,2-diaminoethane-substituted analogues [Ru₃O₂(NH₃)₁₀(en)₂]⁶⁺, [Ru₃O₂(NH₃)₁₀(en)₂]⁷⁺, and their deuteriates. The a_1g and some of the a_2u fundamentals of these cations have been assigned and force-constant calculations on these modes carried out. The excitation profiles of the a_1g fundamentals have maxima close to the intense peaks, which lie between 18 400 and 21 800 cm^–1, in the electronic absorption spectra of these ions, and this information, together with Raman depolarisation data, lead to assignments for the resonant electronic transition in each case.