Facile oxygenation reactions of ruthenium acetylide complex containing substituted olefinic group

η6-Coordinated ruthenabenzenes from three-component assembly on a diruthenium μ-allenyl scaffold

The room temperature reactions with internal alkynes, RCCR, of the μ-allenyl acetonitrile complex [Ru₂Cp₂(CO)₂(NCMe){μ-η¹:η²-C¹HC²C³Me₂}]BF₄ (1-NCMe), freshly prepared from the tricarbonyl precursor [Ru₂Cp₂(CO)₃{μ-η¹:η²-C¹HC²C³Me₂}]BF₄, 1, proceeded with alkyne insertion into ruthenium-allenyl bond and allenyl-CO coupling, affording compounds [Ru₂Cp₂(CO)₂{μ-η²:η⁵-C(R)C(R)C¹HC²(C³MeCH₂)C(OH)}]BF₄ (R = Ph, 2; R = CO₂Me, 3; R = CO₂Et, 4) in 83-94% yields. Deprotonation of 2-4 by triethylamine gave [Ru₂Cp₂(CO)₂{μ-η²:η⁵-C(R)C(R)CHC(CMeCH₂)C(O)}] (R = Ph, 5; R = CO₂Me, 6; R = CO₂Et, 7) in 75-88% yields, and 2-4 could be recovered upon HBF₄·Et₂O addition to 5-7. All the products, 2-7, were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. The structure of 2 was ascertained by single crystal X-ray diffraction and investigated by DFT calculations, revealing a six-membered ruthenacycle with Shannon aromaticity index in line with related compounds. The formation of ruthenium-coordinated ruthenabenzenes from a preexistent diruthenium scaffold is a versatile but underdeveloped approach exploiting cooperative effects typical of a dimetallic core.

Reactions of Ruthenium Complexes Containing Pentatetraenylidene Ligand

Two ruthenium acetylide complexes [Ru]-C≡C-C≡C-C(OR)(C₃ H₅ )₂ (2, R=H and 2 a, R=CH₃ ; [Ru]=Cp(PPh₃ )₂ Ru) each with two cyclopropyl rings were synthesized from TMS-C≡C-C≡C-C(OH)(C₃ H₅ )₂ (1; TMS=trimethylsilyl). Treatments of 2 and 2 a with allyl halide in the presence of KPF₆ afforded the vinylidene complexes 3 and 3 a, respectively. When NH₄ PF₆ was used, instead of KPF₆ , additional ring-opening reaction took place on one of the three-membered ring. Treatment of [Ru]Cl with 1,3-butadiyne (6), bearing an epoxide ring, afforded acetylide complex 7 with a furyl ring. Treatment of 2 a with Ph₃ CPF₆ presumably afforded pentatetraenylidene complex {[Ru]=C=C=C=C=C(C₃ H₅ )₂ }[PF₆ ] (10), which was not isolated. Additions of various alcohols in a solution of 10 generated a number of disubstituted allenylidene complexes {[Ru]=C=C=C(OR)-C=C(C₃ H₅ )₂ }[PF₆ ] (11). Treatment of 11 with K₂ CO₃ afforded the acetylide complex 12 bearing a carbonyl group, characterized by single X-ray diffraction analysis. Addition of a primary amine to 10 caused cleavage of the farthermost C=C bond and several allenylidene complexes {[Ru]=C=C=C(Me)(NHR)}[PF₆ ] (18) were isolated.

The ruthenium-catalysed selective synthesis of mono-deuterated terminal alkynes

A highly efficient catalytic system is reported for chemoselective synthesis of mono-deuterated terminal alkynes using deuterium oxide in which the reaction proceeds via Ru–acetylide intermediates formed by selective activation of the sp-CH bond.