The cyanamide stretching frequencies of the mixed-valence complexes [{Ru(NH
3)
5}
2(
-L)]
3+,
trans,
trans-[{Ru(NH
3)
4(py)}
2(
-L)]
3+ (py = pyridine), and
mer,
mer-[{Ru(NH
3)
3(bpy)}
2(
-L)]
3+ (bpy = 2,2'-bipyridine), where L is the 1,4-dicyanamidobenzene dianion and its substituted derivatives in nitromethane,acetonitrile, and dimethyl sulfoxide, were examined to determine the effects of inner- and outer-sphereperturbation on electron delocalization. The solvent-dependent infrared spectra of [{Ru(NH
3)
5}
2(
-Me
2dicyd)]
3+,where Me
2dicyd
2- is the 2,5-dimethyl-1,4-dicyanamidobenzene dianion, yield evidence for a transformationfrom localized to delocalized behavior and confirm the effect of outer-sphere perturbation on the mixed-valence state. The IR spectrum of
trans,
trans-[{Ru(NH
3)
4(py)}
2(
-Me
2dicyd)]
3+ in acetonitrile is consistentwith Class III properties, and this complex's properties can be regarded as benchmarks for delocalization inour systems. It is shown that this complex obeys the general condition for delocalization in symmetric mixed-valence complexes, 2
H =
, and possesses an experimental free energy of resonance exchange
Gr' = 1250cm
-1 and resonance exchange integral
H = 3740 cm
-1.
