No IVCT Transitions but Splitting of Redox Waves in Ruthenium Compounds with Flexible Saturated Phosphine Bridges

In this work, we synthesized and fully characterized two binuclear saturated phosphine‐bridged compounds and their one‐electron oxidation products, [CpRu( μ ‐modppe)Cl] 2 ( 1 ), [CpRu( μ ‐modppe)Cl] 2 [PF 6 ] ( 1 + ), [CpRu( μ ‐modppb)Cl] 2 ( 2 ), [CpRu( μ ‐modppb)Cl] 2 [PF 6 ] ( 2 + ) (Cp=cyclopentadienyl, modppe=1,2‐Bis(di(4‐methoxyphenyl)‐phosphino)ethane, modppb=1,4‐Bis(di(4‐methoxyphenyl)‐phosphino)butane). Electrochemical measurements show the redox splitting of 277 and 104 mV between the two Ru II centres of complexes 1 and 2 . But, the UV/vis‐NIR spectra of 1 + and 2 + show that the absorption peak in the NIR region should be the d‐d electronic transition of the Ru III centre. So, complexes 1 + and 2 + should be ascribed to class I mixed valence compounds. In addition, we obtained the single‐crystal structure of Class I mixed‐valence compound 1 + , while compound 2 + crystallizes into a special co‐crystal 2 + · 0.5 2 2+ .