Ambiphilic boryl groups in a neutral Ni(ii ) complex: a new activation mode of H2
| Autor: | Amor Rodríguez, Giuseppe Sciortino, Francisco Fernández de Córdova, Agustí Lledós, Pablo Ríos, Javier Borge |
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| Přispěvatelé: | Ministerio de Economía y Competitividad (España), Universidad de Sevilla. Departamento de Química orgánica, Ministerio de Economia, Industria y Competitividad (MINECO). España |
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Scopus RUO. Repositorio Institucional de la Universidad de Oviedo Universidad de las Islas Baleares idUS. Depósito de Investigación de la Universidad de Sevilla instname Digital.CSIC. Repositorio Institucional del CSIC |
| ISSN: | 2041-6539 2041-6520 |
| DOI: | 10.1039/d0sc06014c |
| Popis: | The concept of metal–ligand cooperation opens new avenues for the design of catalytic systems that may offer alternative reactivity patterns to the existing ones. Investigations of this concept with ligands bearing a boron center in their skeleton established mechanistic pathways for the activation of small molecules in which the boron atom usually performs as an electrophile. Here, we show how this electrophilic behavior can be modified by the ligand trans to the boron center, evincing its ambiphilic nature. Treatment of diphosphinoboryl (PBP) nickel–methyl complex 1 with bis(catecholato)diboron (B2Cat2) allows for the synthesis of nickel(II) bis-boryl complex 3 that promotes the clean and reversible heterolytic cleavage of dihydrogen leading to the formation of dihydroborate nickel complex 4. Density functional theory analysis of this reaction revealed that the heterolytic activation of H2 is facilitated by the cooperation of both boryl moieties and the metal atom in a concerted mechanism that involves a Ni(II)/Ni(0)/Ni(II) process. Contrary to 1, the boron atom from the PBP ligand in 3 behaves as a nucleophile, accepting a formally protic hydrogen, whereas the catecholboryl moiety acts as an electrophile, receiving the attack from the hydride-like fragment. This manifests the dramatic change in the electronic properties of a ligand by tuning the substituent trans to it and constitutes an unprecedented cooperative mechanism that involves two boryl ligands in the same molecule operating differently, one as a Lewis acid and the other one as a Lewis base, in cooperation with the metal. In addition, reactivity towards different nucleophiles such as amines or ammonia confirmed the electrophilic nature of the Bcat moiety, allowing the formation of aminoboranes. MINECO (Projects CTQ2016-76267-P, CTQ2017-87889-P, PID2019- 109312GB-IOO and RED2018-102387-T) |
| Databáze: | OpenAIRE |
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