A Diruthenium‐Based Mixed Spin Complex Ru₂⁵⁺(S=1/2)‐CN‐Ru₂⁵⁺(S=3/2)

Abstract

An unusual tetra‐nuclear linear cyanido‐bridged complex [Ru2(μ‐ap)4‐CN‐Ru2(μ‐ap)4](BPh4) (1) (ap=2‐anilinopyridinate) has been synthesized and well characterized. The crystallographic data, magnetic measurement, IR, EPR and theoretical calculation results demonstrate that complex 1 is the first example of mixed spin Ru25+‐based complex with uncommon electronic configurations of S=1/2 for the cyanido‐C bound Ru25+ and S=3/2 for the cyanido‐N bound Ru25+. This phenomenon can be understood by the theoretical calculation results that from the precursor Ru2(μ‐ap)4(CN) (S=3/2) to complex 1 the energy gap between π* and δ* orbitals of the cyanido‐C bound Ru25+ core increases from 0.57 to 1.61 eV due to the enhancement of asymmetrical π back‐bonding effect, but that of the cyanido‐N bound Ru25+ core is essential identical (0.56 eV). Besides, the analysis of UV/Vis‐NIR spectra suggests that there exists metal to metal charge transfer (MMCT) from the cyanido‐N bound Ru25+ (S=3/2) to the cyanido‐C bound Ru25+ (S=1/2), supported by the TDDFT calculations.

Influence of Fine Ligand Substitution Modification of the Isocyanidometal Bridge on Metal‐to‐Metal Charge Transfer Properties in Class II–III Mixed Valence Complexes

“…Mixed valence complexes consisting of two redox sites as the electron donor and acceptor across a bridge are classical experimental models [5] . To explore the electron transfer process and its influencing factors in mixed valence complexes, a large number of mixed valence complexes with charge transfer between redox sites have been synthesized so far [5a,f,6] . According to Robin and Day, mixed valence complexes can be made up of three diverse categories: Class I, non‐interacting or very weakly interacting; Class II, intermediate interacting, but electron localized; Class III, strong interacting, and electron delocalized [7] .…”

Electronic Structure of Ru26+ Complexes with Electron-Rich Anilinopyridinate Ligands

“…Only the ortho H atoms are not observed for Ru 2 6+ compounds. Assignments were again made through a combination of 1 H COSY and comparison with [5][SbCl 6 ] (Figures S3 and S4).…”

Investigation of the electron transfer properties between metal centers in binuclear and trinuclear cyanido-bridged mixed valence complexes with cis/trans-configuration

“…Polynuclear cyanido-bridged mixed valence complexes are ideal research models for the investigation of electron transfer properties between metal centers, which is one of the most fundamental processes in chemical, physical, material and biological systems, 1–6 due to the excellent electron transfer and coordination abilities of the cyanide bridges, 7 the relatively simple structures of these complexes and their potential applications in molecular electronics, 8,9 molecular magnetism, 10,11 molecular devices, 12 and so on. So far, a large number of polynuclear cyanido-bridged mixed valence complexes have been synthesized and characterized.…”