Recent progress in the chemistry of osmium carbyne and metallabenzyne complexes

3.3.2. Half-Sandwich Complexes 3523 3.4. Group 9 Metals 3526 3.5. Group 10 Metals 3527 4. Preparation of Higher Cumulenylidene Complexes 3527 5. Reactivity of Allenylidene Complexes 3528 5.1. General Considerations 3528 5.2. Reactions of Allenylidene Complexes 3528 5.2.1. Group 6 Metals 3528 5.2.2. Group 7 Metals 3529 5.2.3. Group 8 Metals 3530 5.2.4. Group 9 Metals 3537 6. Reactivity of Higher Cumulenylidene Complexes 3538 6.1. Reactions of Butatrienylidene Complexes 3538 6.2. Reactions of Pentatetraenylidene Complexes 3539 7. Catalytic Reactions Involving Allenylidene Complexes 3539

Allenylidene and Higher Cumulenylidene Complexes

Osmium–carbon double bonds: Formation and reactions

C−C Coupling and C−H Bond Activation Reactions of Cyclopentadienyl−Osmium Compounds: The Rich and Varied Chemistry of Os(η5-C5H5)Cl(PiPr3)2 and Its Major Derivatives

The allenylidene−ruthenium complexes [(η6-arene)RuCl(CCCR2)(PR‘3)]OTf (R2 = Ph; fluorene, Ph, Me; PR‘3 = PCy3, PiPr3, PPh3) (OTf = CF3SO3) on protonation with HOTf at −40 °C are completely transformed into alkenylcarbyne complexes [(η6-p-cymene)RuCl(⋮CCHCR2)(PR3)](OTf)2. At −20 °C the latter undergo intramolecular rearrangement of the allenylidene ligand, with release of HOTf, into the indenylidene group in derivatives [(η6-arene)RuCl(indenylidene)(PR3)]OTf. The in situ-prepared indenylidene−ruthenium complexes are efficient catalyst precursors for ring-opening metathesis polymerization of cyclooctene and cyclopentene, reaching turnover frequencies of nearly 300 s-1 at room temperature. Isolation of these derivatives improves catalytic activity for the ring-closing metathesis of a variety of dienes and enynes. A mechanism based on the initial release of arene ligand and the in situ generation of the active catalytic species RuCl(OTf)(CH2)(PR3) is proposed.

Allenylidene-to-indenylidene rearrangement in arene-ruthenium complexes: a key step to highly active catalysts for olefin metathesis reactions.

A Four-Electron π-Alkyne Complex as Precursor for Allenylidene Derivatives: Preparation, Structure, and Reactivity of [Os(η5-C5H5)(CCCPh2)L(PiPr3)]PF6 (L = CO, PHPh2)

Adriana Asensio

Papers

A Four-Electron π-Alkyne Complex as Precursor for Allenylidene Derivatives: Preparation, Structure, and Reactivity of [Os(η5-C5H5)(CCCPh2)L(PiPr3)]PF6 (L = CO, PHPh2)