136379-20-9Relevant articles and documents
Oxidative transformation of [RCp(CO)2MnSR]? Radicals into inidene compounds [RCp(CO)2Mn]2SR+
Lau, Patrizia,Braunwarth, Horst,Huttner, Gottfried,Günauer, Diethelm,Evertz, Kaspar,Imhof, Wolfgang,Emmerich, Christiane,Zsolnai, Laszlo
, p. 3861 - 3873 (2008/10/08)
Stable radical compounds [RCp(CO)2MnSR]? (RCp = Cp, Cp′, Cp*; 1?) have been obtained by air oxidation of the primary products formed from RSH and RCp(CO)2Mn(THF) for a wide variety of alkyl and aryl substituents R. EPR spectra and bulk susceptibility measurements together with solution and solid-state UV/vis spectra show that compounds 1? are stable monomeric radicals. Preparative oxidation of 1? by AgPF6 yields the binuclear species [RCp(CO)2Mn]2SR+PF6 - ([2+] [PF6-]). The cations 2+ exist either as inidene -type compounds LnM..-S(R)..-MLn (LnM = RCp(CO)2Mn) with a trigonal-planar coordination at the bridging sulfur or in the ring-closed isomeric form [LnM-S(R)-MLn]+ with a metal-metal bond and a pyramidal sulfur. The two isomeric forms of 2+ are easily distinguished by their UV/vis spectra. Intense long-wavelength π-π* absorptions are characteristic of the inidene-type isomers. Cyclic voltammetry reveals reversible one-electron redox reactions for 1?as well as for 2? corresponding to 1- ? 1? ? 1+ and 2- ? 2? ? 2+, respectively. It is observed that the reduction of 1+ is about 500 mV less negative as compared to the reduction of 2+ throughout. This finding corresponds to the relative stability of the LUMO's of 1+ (olefinic type π-system) versus those of 2+ (allylic type π-system) as visualized by qualitative MO reasoning. X-ray structural data are presented for [RCp(CO)2MnSR]? (RCp = Cp, R = Ph, 1a?; RCp = Cp′, R = C6F5, 1f?) and [RCp(CO)2Mn]2SR+PF6 - (RCp = Cp, R = pNO2-C6H4, [2b+][PF6-]; RCp = Cp′, R = iPr, [2H+][PF6-]; RCp = Cp′, R = tBu, [2i+][PF6-]).