Peng-Bo Jin, Qian-Cheng Luo, Gemma K. Gransbury, Richard E. P. Winpenny, David P. Mills and Yan-Zhen Zheng
{"title":"Rare earth benzene tetraanion-bridged amidinate complexes†","authors":"Peng-Bo Jin, Qian-Cheng Luo, Gemma K. Gransbury, Richard E. P. Winpenny, David P. Mills and Yan-Zhen Zheng","doi":"10.1039/D4SC05982D","DOIUrl":null,"url":null,"abstract":"<p >The benzene tetraanion-bridged rare earth inverse arene amidinate complexes [{Ln(κ<small><sup>1</sup></small>:η<small><sup>6</sup></small>-Piso)}<small><sub>2</sub></small>(μ-η<small><sup>6</sup></small>:η<small><sup>6</sup></small>-C<small><sub>6</sub></small>H<small><sub>6</sub></small>)] (<strong>2-Ln</strong>, Ln = Gd, Tb, Dy, Y; Piso = {(NDipp)<small><sub>2</sub></small>C<small><sup><em>t</em></sup></small>Bu}, Dipp = C<small><sub>6</sub></small>H<small><sub>3</sub></small><small><sup>i</sup></small>Pr<small><sub>2</sub></small>-2,6) were prepared by the reduction of parent Ln(<small>III</small>) bis-amidinate halide precursors [Ln(Piso)<small><sub>2</sub></small>X] (Ln = Tb, Dy; X = Cl, I) or [Ln(Piso)<small><sub>2</sub></small>I] (Ln = Gd, Y) with 3 eq. KC<small><sub>8</sub></small> in benzene, or by the reaction of the homoleptic Ln(<small>II</small>) complexes [Ln(Piso)<small><sub>2</sub></small>] (Ln = Tb, Dy) with 2 eq. KC<small><sub>8</sub></small> in benzene. The arene exchange reaction of <strong>2-Tb</strong> with toluene gave crystals of [{Tb(κ<small><sup>1</sup></small>:η<small><sup>6</sup></small>-Piso)}<small><sub>2</sub></small>(μ-η<small><sup>6</sup></small>:η<small><sup>6</sup></small>-C<small><sub>7</sub></small>H<small><sub>8</sub></small>)] (<strong>3-Tb</strong>), while no reactions were observed when C<small><sub>6</sub></small>D<small><sub>6</sub></small> solutions of <strong>2-Y</strong> were separately treated with biphenyl, naphthalene or anthracene. The reactivity study shows that <strong>2-Y</strong> can behave as a four-electron reductant to reduce 1,3,5,7-cyclooctatetraene (COT). Complexes <strong>2-Ln</strong> were characterized by single crystal X-ray diffraction, elemental analysis, SQUID magnetometry, UV-vis-NIR, ATR-IR, NMR, density functional theory (DFT) and <em>ab initio</em> calculations. These data consistently show that <strong>2-Ln</strong> formally contain Ln(<small>III</small>) centres with arene-capped inverse-sandwich Dipp–Ln(<small>III</small>)–(C<small><sub>6</sub></small>H<small><sub>6</sub></small>)<small><sup>4−</sup></small>–Ln(<small>III</small>)–Dipp configurations, and DFT calculations on a model of <strong>2-Y</strong> revealed strong Y–(C<small><sub>6</sub></small>H<small><sub>6</sub></small>)<small><sup>4−</sup></small> δ-bonding interactions between the filled π-orbitals of the benzene tetraanion and vacant 4d orbitals of the Y(<small>III</small>) ions. A strong intermolecular coupling interaction between the two Tb(<small>III</small>) centres in <strong>2-Tb</strong> (<em>J</em><small><sub>tot</sub></small> = −6.84 cm<small><sup>−1</sup></small>) was evidenced by a step in a magnetization <em>vs.</em> field plot of <strong>2-Tb</strong> at <em>ca</em>. 3.4 T at 2 K, which we attribute to an anti-ferromagnetic transition of the magnetic moment; we also determined an exchange coupling constant <em>J</em><small><sub>ex</sub></small> = −0.25(1) cm<small><sup>−1</sup></small> for <strong>2-Gd</strong>.</p>","PeriodicalId":9909,"journal":{"name":"Chemical Science","volume":" 4","pages":" 1907-1924"},"PeriodicalIF":7.6000,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/sc/d4sc05982d?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Science","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2025/sc/d4sc05982d","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 benzene tetraanion-bridged rare earth inverse arene amidinate complexes [{Ln(κ1:η6-Piso)}2(μ-η6:η6-C6H6)] (2-Ln, Ln = Gd, Tb, Dy, Y; Piso = {(NDipp)2CtBu}, Dipp = C6H3iPr2-2,6) were prepared by the reduction of parent Ln(III) bis-amidinate halide precursors [Ln(Piso)2X] (Ln = Tb, Dy; X = Cl, I) or [Ln(Piso)2I] (Ln = Gd, Y) with 3 eq. KC8 in benzene, or by the reaction of the homoleptic Ln(II) complexes [Ln(Piso)2] (Ln = Tb, Dy) with 2 eq. KC8 in benzene. The arene exchange reaction of 2-Tb with toluene gave crystals of [{Tb(κ1:η6-Piso)}2(μ-η6:η6-C7H8)] (3-Tb), while no reactions were observed when C6D6 solutions of 2-Y were separately treated with biphenyl, naphthalene or anthracene. The reactivity study shows that 2-Y can behave as a four-electron reductant to reduce 1,3,5,7-cyclooctatetraene (COT). Complexes 2-Ln were characterized by single crystal X-ray diffraction, elemental analysis, SQUID magnetometry, UV-vis-NIR, ATR-IR, NMR, density functional theory (DFT) and ab initio calculations. These data consistently show that 2-Ln formally contain Ln(III) centres with arene-capped inverse-sandwich Dipp–Ln(III)–(C6H6)4−–Ln(III)–Dipp configurations, and DFT calculations on a model of 2-Y revealed strong Y–(C6H6)4− δ-bonding interactions between the filled π-orbitals of the benzene tetraanion and vacant 4d orbitals of the Y(III) ions. A strong intermolecular coupling interaction between the two Tb(III) centres in 2-Tb (Jtot = −6.84 cm−1) was evidenced by a step in a magnetization vs. field plot of 2-Tb at ca. 3.4 T at 2 K, which we attribute to an anti-ferromagnetic transition of the magnetic moment; we also determined an exchange coupling constant Jex = −0.25(1) cm−1 for 2-Gd.
期刊介绍:
Chemical Science is a journal that encompasses various disciplines within the chemical sciences. Its scope includes publishing ground-breaking research with significant implications for its respective field, as well as appealing to a wider audience in related areas. To be considered for publication, articles must showcase innovative and original advances in their field of study and be presented in a manner that is understandable to scientists from diverse backgrounds. However, the journal generally does not publish highly specialized research.