Coffinet Anaïs, Zhang Dan, Vendier Laure, Bontemps Sébastien, Simonneau Antoine
LCC-CNRS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, BP44099, F-31077 Toulouse cedex 4, France.
Dalton Trans. 2021 Apr 28;50(16):5582-5589. doi: 10.1039/d1dt00317h.
The borylation of ligated dinitrogen by 1,3-B-H bond addition over a W-N[triple bond, length as m-dash]N unit using various hydroboranes has been examined. In a previous study, we have shown that Piers' borane (1) reacted with the tungsten dinitrogen complex 2 to afford a boryldiazenido-hydrido-tungsten species. The ease and mildness of this reaction have encouraged us to extend its scope, with the working hypothesis that 1 could potentially catalyse the 1,3-B-H bond addition of other hydroboranes. Under productive reaction conditions, dicyclohexylborane (HBCy2) and diisopinocampheylborane (HBIpc2) underwent retro-hydroboration to give cyclohexylborane (H2BCy) or isopinocampheylborane (H2BIpc), respectively; these monoalkylboranes act as N2-borylating agents in the presence of a catalytic amount of 1. Under similar conditions, 9-borabicyclononane (9-BBN) slowly adds over the W-N[triple bond, length as m-dash]N unit without rearrangement to a monoalkylborane. Catecholborane (HBcat) undergoes the 1,3-B-H bond addition without the need for a catalyst. We were not able to build more than one covalent B-N bond between the terminal N of the N2 ligand and the boron reagent with this methodology.
使用各种硼烷通过1,3 - B - H键加成在W - N≡N单元上对连接的二氮进行硼氢化反应已被研究。在先前的研究中，我们已经表明皮尔斯硼烷（1）与钨二氮配合物2反应生成硼基二氮烯基 - 氢 - 钨物种。该反应的简便性和温和性促使我们扩展其范围，基于1可能潜在地催化其他硼烷的1,3 - B - H键加成这一工作假设。在有效的反应条件下，二环己基硼烷（HBCy₂）和二异松莰基硼烷（HBIpc₂）分别进行逆硼氢化反应生成环己基硼烷（H₂BCy）或异松莰基硼烷（H₂BIpc）；这些单烷基硼烷在催化量的1存在下作为N₂硼化剂。在类似条件下，9 - 硼双环壬烷（9 - BBN）缓慢加成到W - N≡N单元上而不重排为单烷基硼烷。儿茶酚硼烷（HBcat）无需催化剂即可进行1,3 - B - H键加成。使用这种方法，我们无法在N₂配体的末端N与硼试剂之间形成超过一个共价B - N键。
