[Cp*Ru
IVCl
2(S
2CR)] (R = NMe
2, NEt
2, and O
iPr) were synthesized by the reaction of [Cp*Ru
IIICl
2]
2with [RC(S)S]
2. One-electron electrochemical oxidation of [Cp*RuCl
2(S
2CR)] produces paramagnetic[Cp*RuCl
2(S
2CR)]
+, which are stable in CH
2Cl
2 solution for at least several hours at 233 K. EPRexperiments performed at 293 K show isotropic signals (
g 2.035) with clearly defined hyperfine couplingto
99Ru and
101Ru of 25 G and with peak-to-peak line widths of 15 G. At temperatures below 153 K,axial-shaped EPR spectra were obtained with
g-values close to 2 (2.050-2.008) and narrow peak-to-peak line widths (15 G). Results from DFT calculations indicate that approximately 70% of the spindensity in [Cp*RuCl
2(S
2CNMe
2)]
+ is located on the ruthenium, although there is an increase of only0.06 in the positive charge of the metal ion as a result of the oxidation. The high spin density on Rusupports the assignment of a
formally Ru(V) oxidation state, which is unprecedented in organometallicchemistry. Chemical oxidation of Cp*Ru
IVCl
2(S
2CNMe
2) with NO(PF
6) in CH
3CN resulted in the isolationof [Cp*Ru
IV(MeCN)
2(S
2CNMe
2)]
+2 (
4), while oxidation with [(4-Br-C
6H
4)
3N](SbCl
6) in CH
2Cl
2 resultedin the formation of chloro-bridged dimeric [Cp*Ru
IVCl(S
2CNMe
2)]
2+2 (
5). When
5 is dissolved in CD
3CN/CH
3CN, it immediately converts to
4. Cyclic voltammetric experiments confirmed that in both solventsthe chemical oxidation process occurred through the [Cp*Ru
VCl
2(S
2CNMe
2)]
+ intermediate.