Highly Oxidized Ruthenium Organometallic Compounds. The Synthesis and One-Electron Electrochemical Oxidation of [CpRuIVCl2(S2CR)] (Cp = η5-C5Me5, R = NMe2, NEt2, O i Pr)

• Published in: Organometallics Vol. 25; no. 26; pp. 6134 - 6141
• Main Authors: Kuan, Seah Ling, Tay, Elaine Phuay Leng, Leong, Weng Kee, Goh, Lai Yoong, Lin, Ching Yeh, Gill, Peter M. W, Webster, Richard D
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18.12.2006
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om060866z

[Cp*RuIVCl2(S2CR)] (R = NMe2, NEt2, and O i Pr) were synthesized by the reaction of [Cp*RuIIICl2]2 with [RC(S)S]2. One-electron electrochemical oxidation of [Cp*RuCl2(S2CR)] produces paramagnetic [Cp*RuCl2(S2CR)]+, which are stable in CH2Cl2 solution for at least several hours at 233 K. EPR experiments performed at 293 K show isotropic signals (g ≈ 2.035) with clearly defined hyperfine coupling to 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 spin density in [Cp*RuCl2(S2CNMe2)]+ is located on the ruthenium, although there is an increase of only 0.06 in the positive charge of the metal ion as a result of the oxidation. The high spin density on Ru supports the assignment of a formally Ru(V) oxidation state, which is unprecedented in organometallic chemistry. Chemical oxidation of Cp*RuIVCl2(S2CNMe2) with NO(PF6) in CH3CN resulted in the isolation of [Cp*RuIV(MeCN)2(S2CNMe2)]+2 (4), while oxidation with [(4-Br-C6H4)3N](SbCl6) in CH2Cl2 resulted in the formation of chloro-bridged dimeric [Cp*RuIVCl(S2CNMe2)]2 +2 (5). When 5 is dissolved in CD3CN/CH3CN, it immediately converts to 4. Cyclic voltammetric experiments confirmed that in both solvents the chemical oxidation process occurred through the [Cp*RuVCl2(S2CNMe2)]+ intermediate.