H<sub>2</sub> addition to (<sup>Me4</sup>PCP)Ir(CO): studies of the isomerization mechanism

Lekich, Travis T.; Gary, J. Brannon; Bellows, Sarina M.; Cundari, Thomas R.; Guard, Louise M.; Heinekey, D. Michael

doi:10.1039/c8dt02861c

“…The successive conformational transformation of 9′‐ cis into 9′‐ trans , changing the side of H‐Rh bond relative to the H−Si bond, proceeds through the formation of μ‐hydride (O=Si←H−Rh) complex as intermediate . Then, the reverse 1,2‐hydrogen migration from Si to Rh center affords the corresponding trans ‐isomer 7′‐ trans . All transformations in the cis / trans isomerization process cost little energy and the trans ‐isomer is only slightly more stable than the cis ‐isomer, which explains the formation of 7‐ trans as the major isomer.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of a Stable N‐Hetero‐Rh^I‐Metallacyclic Silanone

Takahashi

¹

,

Nakaya

²

,

Frutos

³

et al. 2020

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A novel N‐hetero‐RhI‐metallacyclic silanone 2 has been synthesized. The silanone 2, showing an extremely large dimerization energy (ΔG=+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5. The exceptional stability of 2, related to the unusual electronic and steric effects of RhI‐substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII‐dihydride complex 7 and it undergoes a cis/trans‐isomerization via a particular mechanism, demonstrating that addition‐elimination processes can also happen for silanones just like for their carbon analogues!

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“…[21] Then, the reverse 1,2-hydrogen migration from Si to Rh center affords the corresponding trans-isomer 7'-trans. [26] All transformations in the cis/trans isomerization process cost little energy and the trans-isomer is only slightly more stable than the cis-isomer, which explains the formation of 7-trans as the major isomer. Despite the intervention of transition metal moiety, this cis/trans-isomerization (hydride attack on the silanone to form a silanolate intermediate 9/eliminationreaddition of Rh to change sides of RhÀH bond/reverse hydrogen migration to reform the silanone) [21] demonstrates that the addition-elimination process, which is one of the most important reactions of the carbonyl group, can also happen for silanones.…”

Section: Angewandte Chemiementioning

confidence: 99%

Synthesis of a Stable N‐Hetero‐Rh^I‐Metallacyclic Silanone

Takahashi

¹

,

Nakaya

²

,

Frutos

³

et al. 2020

View full text Add to dashboard Cite

A novel N‐hetero‐RhI‐metallacyclic silanone 2 has been synthesized. The silanone 2, showing an extremely large dimerization energy (ΔG=+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5. The exceptional stability of 2, related to the unusual electronic and steric effects of RhI‐substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII‐dihydride complex 7 and it undergoes a cis/trans‐isomerization via a particular mechanism, demonstrating that addition‐elimination processes can also happen for silanones just like for their carbon analogues!

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