Jackson A. Reyna, V. Mahesh Krishnan, Roberto Silva Villatoro, Hadi D. Arman, Sebastian A. Stoian and Zachary J. Tonzetich
{"title":"Square-planar imido complexes of cobalt: synthesis, reactivity and computational study†","authors":"Jackson A. Reyna, V. Mahesh Krishnan, Roberto Silva Villatoro, Hadi D. Arman, Sebastian A. Stoian and Zachary J. Tonzetich","doi":"10.1039/D4DT01483A","DOIUrl":null,"url":null,"abstract":"<p >Treatment of [Co(N<small><sub>2</sub></small>)(<small><sup><em>t</em>Bu</sup></small>PNP)] (<small><sup><em>t</em>Bu</sup></small>PNP = anion of 2,5-bis(di-<em>tert</em>-butylphosphinomethyl)pyrrole) with one equivalent of an aryl azide generates the four-coordinate imido complexes [Co(NAr)(<small><sup><em>t</em>Bu</sup></small>PNP)] (Ar = mesityl, phenyl, or 4-<small><sup><em>t</em></sup></small>Bu-phenyl). X-ray crystallographic analysis of the compounds shows an unusual square-planar geometry about cobalt with nearly linear imido units. In the presence of the hydrogen atom donor, TEMPOH, [Co(NPh)(<small><sup><em>t</em>Bu</sup></small>PNP)] undergoes addition of the H atom to the imido nitrogen to generate the corresponding amido complex, [Co(NHPh)(<small><sup><em>t</em>Bu</sup></small>PNP)], whose structure and composition were verified by independent synthesis. Despite the observation of H atom transfer reactivity with TEMPOH, the imido complexes do not show catalytic activity for C–H amination or aziridination for several substrates examined. In the case of [Co(NPh)(<small><sup><em>t</em>Bu</sup></small>PNP)], addition of excess azide produced the tetrazido complex, [Co(N<small><sub>4</sub></small>Ph<small><sub>2</sub></small>)(<small><sup><em>t</em>Bu</sup></small>PNP)], whose bond metrics were most consistent with an anionic Ph<small><sub>2</sub></small>N<small><sub>4</sub></small> ligand. Density Functional Theory (DFT) investigations of the imido and tetrazido species suggest that they adopt a ground state best described as possessing a low-spin cobalt(<small>II</small>) ion ferromagnetically coupled to an iminyl radical.</p>","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Dalton Transactions","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/dt/d4dt01483a","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, INORGANIC & NUCLEAR","Score":null,"Total":0}
引用次数: 0
Abstract
Treatment of [Co(N2)(tBuPNP)] (tBuPNP = anion of 2,5-bis(di-tert-butylphosphinomethyl)pyrrole) with one equivalent of an aryl azide generates the four-coordinate imido complexes [Co(NAr)(tBuPNP)] (Ar = mesityl, phenyl, or 4-tBu-phenyl). X-ray crystallographic analysis of the compounds shows an unusual square-planar geometry about cobalt with nearly linear imido units. In the presence of the hydrogen atom donor, TEMPOH, [Co(NPh)(tBuPNP)] undergoes addition of the H atom to the imido nitrogen to generate the corresponding amido complex, [Co(NHPh)(tBuPNP)], whose structure and composition were verified by independent synthesis. Despite the observation of H atom transfer reactivity with TEMPOH, the imido complexes do not show catalytic activity for C–H amination or aziridination for several substrates examined. In the case of [Co(NPh)(tBuPNP)], addition of excess azide produced the tetrazido complex, [Co(N4Ph2)(tBuPNP)], whose bond metrics were most consistent with an anionic Ph2N4 ligand. Density Functional Theory (DFT) investigations of the imido and tetrazido species suggest that they adopt a ground state best described as possessing a low-spin cobalt(II) ion ferromagnetically coupled to an iminyl radical.
将 [Co(N2)(tBuPNP)](tBuPNP = 2,5-双(二叔丁基膦甲基)吡咯的阴离子)与一个等效的芳基叠氮化物处理,可生成四配位亚胺配合物 [Co(NAr)(tBuPNP)](Ar = 甲苯甲基、苯基或 4-tBu-苯基)。这些化合物的 X 射线晶体学分析表明,钴与近似线性的亚氨基单元呈不寻常的方形平面几何结构。在氢原子供体 TEMPOH 的存在下,[Co(NPh)(tBuPNP)] 会发生 H 原子与亚氨基氮的加成反应,生成相应的氨基复合物 [Co(NHPh)(tBuPNP)],其结构和组成已通过独立合成得到验证。尽管观察到了 H 原子与 TEMPOH 的转移反应性,但对于所研究的几种底物,亚氨基配合物并没有显示出 C-H amination 或叠氮化的催化活性。就[Co(NPh)(tBuPNP)]而言,加入过量叠氮化物会产生四氮配合物[Co(N4Ph2)(tBuPNP)],其键的度量最符合阴离子 Ph2N4 配体。密度泛函理论(DFT)研究表明,亚氨基和四氮杂羰基复合物的基态最适合描述为拥有一个与亚氨基自由基铁磁耦合的低自旋钴(II)离子。
期刊介绍:
Dalton Transactions is a journal for all areas of inorganic chemistry, which encompasses the organometallic, bioinorganic and materials chemistry of the elements, with applications including synthesis, catalysis, energy conversion/storage, electrical devices and medicine. Dalton Transactions welcomes high-quality, original submissions in all of these areas and more, where the advancement of knowledge in inorganic chemistry is significant.