Osvaldo Ordoñez, Xiaojuan Yu, Megan A Schuerlein, Guang Wu, Jochen Autschbach, Trevor W Hayton
{"title":"An Actinide Complex with a Nucleophilic Allenylidene Ligand.","authors":"Osvaldo Ordoñez, Xiaojuan Yu, Megan A Schuerlein, Guang Wu, Jochen Autschbach, Trevor W Hayton","doi":"10.1021/jacs.4c09076","DOIUrl":null,"url":null,"abstract":"<p><p>The reaction of [Cp<sub>3</sub>Th(3,3-diphenylcyclopropenyl)] (Cp = η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(Et<sub>2</sub>O)<sub>2</sub>][Cp<sub>3</sub>Th(CCCPh<sub>2</sub>)] ([Li(Et<sub>2</sub>O)<sub>2</sub>][<b>1</b>]), in good yield. Additionally, deprotonation of [Cp<sub>3</sub>Th(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.2-cryptand, results in the formation of discrete cation/anion pairs, [Li(12-crown-4)(THF)][Cp<sub>3</sub>Th(CCCPh<sub>2</sub>)] ([Li(12-crown-4)(THF)][<b>1</b>]) and [Li(2.2.2-cryptand)][Cp<sub>3</sub>Th(CCCPh<sub>2</sub>)] ([Li(2.2.2-cryptand)][<b>1</b>]), respectively. Interestingly, the complex [Li(Et<sub>2</sub>O)<sub>2</sub>][<b>1</b>] undergoes dimerization upon standing at room temperature, resulting in the formation of [Cp<sub>2</sub>Th(μ:η<sup>1</sup>:η<sup>3</sup>-CCCPh<sub>2</sub>)]<sub>2</sub> (<b>2</b>), via loss of LiCp. The reaction of [Li(Et<sub>2</sub>O)<sub>2</sub>][<b>1</b>] with MeI results in electrophilic attack at the C<sub>γ</sub> carbon atom, leading to the formation of a thorium acetylide complex, [Cp<sub>3</sub>Th(C≡CC(Me)Ph<sub>2</sub>)] (<b>3</b>), which can be isolated in 83% yield upon workup, whereas the reaction of [Li(Et<sub>2</sub>O)<sub>2</sub>][<b>1</b>] with benzophenone results in the formation of 1,1,4,4-tetraphenylbutatriene (<b>4</b>) in 99% yield, according to integration against an internal standard. Density functional theory (DFT) calculations performed on [<b>1</b>]<sup>-</sup> and <b>2</b> reveal significant electron delocalization across the allenylidene ligand. Additionally, calculations of the <sup>13</sup>C NMR chemical shifts for the C<sub>α</sub>, C<sub>β</sub>, and C<sub>γ</sub> nuclei of the allenylidene ligand were in good agreement with the experimental shifts. The calculations reveal modest deshielding induced by spin-orbital effects originating at Th due to the involvement of the 5f orbitals in the Th-C bonds. According to a DFT analysis, the cyclopropenyl ring-opening reaction proceeds via [Cp<sub>3</sub>Th(η<sup>1</sup>-3,3-Ph<sub>2</sub>-<i>cyclo</i>-C<sub>3</sub>)]<sup>-</sup> (<b>IM</b>), which features a carbanion character at C<sub>β</sub>.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":null,"pages":null},"PeriodicalIF":14.4000,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the American Chemical Society","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/jacs.4c09076","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The reaction of [Cp3Th(3,3-diphenylcyclopropenyl)] (Cp = η5-C5H5) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(Et2O)2][Cp3Th(CCCPh2)] ([Li(Et2O)2][1]), in good yield. Additionally, deprotonation of [Cp3Th(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.2-cryptand, results in the formation of discrete cation/anion pairs, [Li(12-crown-4)(THF)][Cp3Th(CCCPh2)] ([Li(12-crown-4)(THF)][1]) and [Li(2.2.2-cryptand)][Cp3Th(CCCPh2)] ([Li(2.2.2-cryptand)][1]), respectively. Interestingly, the complex [Li(Et2O)2][1] undergoes dimerization upon standing at room temperature, resulting in the formation of [Cp2Th(μ:η1:η3-CCCPh2)]2 (2), via loss of LiCp. The reaction of [Li(Et2O)2][1] with MeI results in electrophilic attack at the Cγ carbon atom, leading to the formation of a thorium acetylide complex, [Cp3Th(C≡CC(Me)Ph2)] (3), which can be isolated in 83% yield upon workup, whereas the reaction of [Li(Et2O)2][1] with benzophenone results in the formation of 1,1,4,4-tetraphenylbutatriene (4) in 99% yield, according to integration against an internal standard. Density functional theory (DFT) calculations performed on [1]- and 2 reveal significant electron delocalization across the allenylidene ligand. Additionally, calculations of the 13C NMR chemical shifts for the Cα, Cβ, and Cγ nuclei of the allenylidene ligand were in good agreement with the experimental shifts. The calculations reveal modest deshielding induced by spin-orbital effects originating at Th due to the involvement of the 5f orbitals in the Th-C bonds. According to a DFT analysis, the cyclopropenyl ring-opening reaction proceeds via [Cp3Th(η1-3,3-Ph2-cyclo-C3)]- (IM), which features a carbanion character at Cβ.
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