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.
η6-Coordinated ruthenabenzenes from three-component assembly on a diruthenium μ-allenyl scaffold
M. Bortoluzzi;
2022-01-01
Abstract
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.
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