Search

The one-electron oxidation of Cp*(dppf)RuH, where Cp* = pentamethylcyclopentadienide; dppf = 1,1'-bis(diphenylphosphino)ferrocene, affords the formation of a meta-stable heterobimetallic mixed-valence ion, Fe(II),Ru(III). The results showed that the 17-electron Ru(III) hydride derivative is essential to the performance of Cp*(dppf)RuH as a redox switch catalyst.

Research has been conducted on dihydrogen complexes of Os (super)II amines. The authots describe the study of stability resulting from one electron oxidation of these complexes.

trans-[Os(en)[sub 2]pyH](Otf)[sub 2], 2, is recovered from an acidic solution of trans-[Os(en)[sub 2]py(H[sub 2])](OTf)[sub 2], 1, which has been subjected to one electron oxidation. The structures of both 1 and 2 have been determined by single crystal X-ray analysis. In cyclic voltammetry, 2 shows a one electron oxidation wave at 0.95 V and a one electron reduction wave at -1.2 V, neither accompanied by a signal for the reverse process. Reduction of 2 by Zn/Hg in methanol solution leads to quantitative formation of [Os(en)[sub 2](py)H[sub 2])][sup 2+], predominantly in the trans-form. In aqueous solution, species 2 reacts rapidly with N-methylacridium ion, [MAH][sup +], by hydride transfer. One electron chemical oxidation of 2 to the corresponding Os(IV) is slower than that of 1 to 2 owing to the increase in coordination number when Os(IV) is produced. Treatment of 1, or the cis-form, 1', in DMSO by sodium t-butoxide produces mainly the corresponding isomers of the monohydrides of Os[sup II], that derived from 1' is deep red in color while the transmonohydride is colorless. Both react with [MAH][sup +] to form [MAH][sub 2], and both disappear rapidly in acetone or acetonitrile, presumably by reducing the solvents. Reaction of trans-[Os(NH[sub 3])[sub 4](H[sub 2])H2O](BPh[sub 4])[sub 2], 4, in acetone-d[sub 6] as solvent with either CH[sub 3]CHO or styrene leads to hydrogenation of the substrate. Reactions which compete with trans-[Os(en)[sub 2](η²H[sub 2])(CF[sub 3]SO)[sub 3]]CF[sub 3]SO[sub 3] release of substrate from the trans-complex before isomerization to the cis-form, required for hydrogenation to occur, result in the trans-derivative of the added solute. When H[sub 2]C=CH-CH[sub 2]-SCH[sub 3] is the substrate, binding takes place at sulfur. Complete conversion to the cis-substrate isomer is observed, without hydrogenation occurring even though contact between dihydrogen and the double bond is possible. [ABSTRACT FROM AUTHOR]

Reports on the discovery of a heterobimetallic complex Cp*(dppf)RuH, an active and well-defined catalyst for performing one-electron reductions with H2. Preparation of the Ru(II) hydride; Ability to catalyze the one-electron reduction of MV2+ with H2; Characterization of its 17-electron Ru(III) counterpart as a delocalized mixed-valence metal hydride.