Halogen-mediated electron transfer between metallocenes of ruthenium and osmium in the oxidation states 4+ and 2+

Abstract

The rates of self-exchange for several systems of the class MCp2X+/Cp2, where M is Ru or Os and X is Cl, Br, or I, have been measured by the NMR line-broadening method. For each metal, the rates increase along the halogen series as given above and are more rapid for = Ru than for the osmium analogues. In consideration of these data, the possibility is raised that these 2e self-exchange reactions and those of other metal ions take place by le steps.

Hydride Abstraction Reactivity of Haloruthenoceniums and Haloosmoceniums

“…All reactions are, however, complete within 20 min. The ruthenoceniums are better two-electron oxidants than the corresponding osmoceniums …”

“…All materials were obtained from commercial sources and used as received unless otherwise indicated. [Cp 2 MX]PF 6 (M = Ru, Os; X = Cl, Br, I), [CpRu(C 5 H 4 )COOH], and [CpRu(C 5 H 4 CH 2 Ph)] were prepared according to literature methods.…”

“…In particular, the possibility of multiple reactivity pathways paralleling those of metal oxo complexes has not been fully established. The halometallocenium species [Cp 2 MX] + (M = Ru, Os; X = Cl, Br, I) have been shown to undergo self-exchange or net chemical reactions with metallocenes − as shown in eq 1: …”

Characterization of the Inorganic/Organometallic Osmium(IV) Compound [Cp2 OsIVCl]2 [OsIVCl6] as Formed by the Reaction of OSCI3 with Pentamethylcyclopentadiene in Air

“…Extensive addition and substi tution reactivity yields an ionic product consisting of the w ell-know n hexachloroosm ate(IV ) dianion and two equivalents of the [Cp*2 0 sIVC l]+ cation, a less com m on representative o f an im portant class o f organom etallic species [8,10]. Incidentally, the related [Cp2 0 sCl]+ ion was obtained through oxi dation of osm ocene with F eC^/H C l [11].…”

Ruthenocenes and Osmocenes

“…The [OsBrCp 2 ]7OsCp 2 system is more strongly oxidizing than ruthenium by 0.036 V; oxidation may take place by successive one-electron steps, depending on the stability of M n -M lv vs. M III -M HI . 96 The kinetics of RuCp 2 /[RuBrCp 2 ] + electron self-exchange, originally considered to involve a composite of free ion and ion-paired pathways, 95 102 Although this suggests that [MCp* 2 ] + * acts as a proton acceptor, there is also ready dimerization of the osmium cation to form a dimer. The cation readily adds amines, phenols and hydroxide to give Rc*X (X = NR 2 , OR, OH) quantitatively.…”