The complexes [Ru(1-C
C-1,10-C
2B
8H
9)(dppe)Cp*] (
3a), [Ru(1-C
C-1,12-C
2B
10H
11)(dppe)Cp*] (
3b), [{Ru(dppe)Cp*}
2{
-1,10-(C
C)
2-1,10-C
2B
8H
8}] (
4a) and [{Ru(dppe)Cp*}
2{
-1,12-(C
C)
2-1,12-C
2B
10H
10}] (
4b), which form a representative series of mono- and bimetallic acetylide complexesfeaturing 10- and 12-vertex carboranes embedded within the diethynyl bridging ligand, have been preparedand structurally characterized. In addition, these compounds have been examined spectroscopically (UV-vis-NIR, IR) in all accessible redox states. The significant separation of the two, one-electron anodic wavesobserved in the cyclic voltammograms of the bimetallic complexes
4a and
4b is largely independent of thenature of the electrolyte and is attributed to stabilization of the intermediate redox products [
4a]
+ and [
4b]
+through interactions between the metal centers across a distance of ca. 12.5 Å. The mono-oxidized bimetalliccomplexes [
4a]
+ and [
4b]
+ exhibit spectroscopic properties consistent with a description of these speciesin terms of valence-localized (class II) mixed-valence compounds, including a unique low-energy electronicabsorption band, attributed to an IVCT-type transition that tails into the IR region. DFT calculations withmodel systems [
4a-H]
+ and [
4b-H]
+ featuring simplified ligand sets reproduce the observed spectroscopicdata and localized electronic structures for the mixed-valence cations [
4a]
+ and [
4b]
+.