The complex [Cp*RuCl(dippe)] reacts with 1-alkynes in MeOH in the presence of NaBPh4, yielding the metastable hydrido−alkynyl derivatives [Cp*Ru(H)(C⋮CR)(dippe)][BPh4] (R = COOMe, Ph or SiMe3), intermediates in the formation of the corresponding vinylidene complexes, to which these compounds rearrange both in solution and in the solid state. The X-ray crystal structures of the isomers [Cp*RuCCHCOOMe(dippe)][BPh4] and [Cp*RuH(C⋮CCOOMe)(dippe)][BPh4] have been determined. Kinetic studies show that the mechanism for this isomerization process seems to be dissociative and that it is inhibited in solution by strong acids. In contrast with this, no hydrido−alkynyl complex has been observed in the course of the reaction of 1-alkynes with [CpRuCl(dippe)]. Instead, the alkyne adducts have been detected, and isolated in some cases. Such species have only been observed in the Cp*Ru system for acetylene, and [Cp*Ru(η2-HC⋮CH)(dippe)]+ seems to be in equilibrium with the corresponding hydrido−alkynyl complex [Cp*RuH(C⋮CH)(dippe)]+, which isomerizes to [Cp*RuCCH2(dippe)]+ via the formation of the π-alkyne complex. The effects on these tautomerization processes of the phosphine, Cp*, and Cp ligands, as well as the R group of the alkyne, are discussed.

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The complexes [CpRuCl(dippe)] and [Cp*RuCl(dippe)] (Cp = C5H5; Cp* = C5Me5; dippe = 1,2-bis(diisopropylphosphino)ethane) react with H2 and Na[BPh4] in EtOH or MeOH to furnish the dihydrides [CpRuH2(dippe)][BPh4] (1) and [Cp*RuH2(dippe)][BPh4] (2). These compounds are deprotonated by KOBut to yield the monohydrides [CpRuH(dippe)] (3) and [Cp*RuH(dippe)] (4), which can be protonated back by HBF4·OEt2 at low temperatures to give the dihydrogen adducts [CpRu(H2)(dippe)][BF4] (5) and [Cp*Ru(H2)(dippe)][BF4] (6). These compounds rearrange irreversibly to the dihydride form as the temperature is raised. A kinetic study of these rearrangement processes suggests that the isomerization mechanism is different in each case. The dinitrogen complex [CpRu(N2)(dippe)][BPh4] (7) and the acetone adduct [CpRu(Me2CO)(dippe)][BPh4] (8) were obtained by reaction of [CpRuCl(dippe)] with Ag+ in acetone under dinitrogen or argon, respectively, followed by NaBPh4/EtOH. Both compounds react with atmospheric oxygen yielding [CpRu(η6-C6H5BPh3)] (9) and iPr2P(O)CH2CH2P(O)iPr2. The dinitrogen adduct [Cp*Ru(N2)(dippe)][BPh4] (10) was also obtained, but it reacts irreversibly with traces of O2 to give the dioxygen complex [Cp*Ru(O2)(dippe)][BPh4], previously known. A range of neutral donors L also react with [CpRuCl(dippe)] or [Cp*RuCl(dippe)] and NaBPh4 furnishing the corresponding complexes [CpRu(L)(dippe)][BPh4] (L = CO (11), CNBut (12), C2H4 (13)), or [Cp*Ru(L)(dippe)][BPh4] (L = CO (14), CNBut (15), C2H4 (16)). The ethylene adduct 16 is only stable under an ethylene atmosphere, whereas 13 is a stable species. The X-ray crystal structures of compounds 2, 12, and 13 are also reported.

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