Multiple MMCT properties of the diruthenium-based cyanido-bridged complex Ru VI2-NC-RuII-CN-Ru VI2

Abstract

The diruthenium-based linear mixed valence complex trans-[Ru₂(ap)₄-NC-Ru(DMAP)₄-CN-Ru₂(ap)₄][PF₆]₂ (1²⁺[PF₆]₂) (ap = 2-anilinopyridinate, DMAP = 4-dimethylaminopyridine) and its two-electron oxidation product 1⁴⁺[PF₆]₄ have been synthesized and fully characterized. The investigation reveals that complex 1²⁺ displays a single MMCT transition, whereas complex 1⁴⁺ has three identified MMCT transitions (MMCT-1, MMCT-2 and MMCT-3) upon oxidation. Interestingly, MMCT-2 in complex 1⁴⁺ might result from the transition from the Ru^III-NC-Ru^II-CN-Ru^III component, which is composed of the central Ru^II and its two neighboring Ru^III atoms from the cluster Ru^VI₂ units, to both the terminal Ru^III atoms of the same cluster Ru^VI₂ units, which is supported by the TDDFT calculations.