Hydride Abstraction Reactivity of Haloruthenoceniums and Haloosmoceniums

Abstract

[Cp2RuCl]PF6 reacts with benzylruthenocene in acetonitrile with a 1:1 stoichiometry to produce Cp2Ru and phenylruthenocenyl methylium cation. Similar hydride abstraction reactivity has also been observed with diruthenocenylmethane, ethylruthenocene, and benzylferrocene. The complexes [Cp2MX]+ (M = Ru, Os; X = Cl, Br, I) also react with leuco crystal violet and leuco malachite green to give the corresponding carbenium ions but do not exhibit any detectable reactivity with triphenylmethane, cycloheptatriene, or xanthene. On the basis of these observations, the pK R + values for the [Cp2MX]+ species are estimated to be between +4.7 and +6.9.

Thermodynamic Studies of [HPt(EtXantphos)2]+ and [(H)2Pt(EtXantphos)2]2+

“…In fact, their name is derived from this property. A number of studies have addressed the issue of kinetic hydricity of metal hydrides, − but only recently have studies of the thermodynamic hydricities begun to appear. − If the metal complex resulting from deprotonation of a transition metal hydride can be oxidized reversibly by two electrons, then free energies for the heterolytic cleavage of the M−H bond to form H - and the corresponding metal complex can be calculated using a simple thermodynamic cycle. This method has been used previously to determine the hydride donor abilities of a number of platinum hydrides of the type [HPt(diphosphine) 2 ] + , and the reliability of this method has been established by cross-checking these values with those obtained for the same complexes from the heterolytic cleavage of hydrogen …”

“…In fact, their name is derived from this property. A number of studies have addressed the issue of kinetic hydricity of metal hydrides, [18][19][20][21][22][23] but only recently have studies of the thermodynamic hydricities begun to appear. [24][25][26][27][28][29][30][31][32] If the metal complex resulting from deprotonation of a transition metal hydride can be oxidized reversibly by two electrons, then free energies for the heterolytic cleavage of the M-H bond to form Hand the corresponding metal complex can be calculated using a simple thermodynamic cycle.…”