5 research outputs found

    Novel Lanthanide Amides Incorporating Neutral Pyrrole Ligand in a Constrained Geometry Architecture: Synthesis, Characterization, Reaction, and Catalytic Activity

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    The first series of lanthanide amido complexes incorporating a neutral pyrrole ligand in a constrained geometry architecture were synthesized, and their bonding, reactions, and catalytic activities were studied. Treatment of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Ln­(μ-Cl)­Li­(THF)<sub>3</sub> with 1 equiv of (<i>N</i>-C<sub>6</sub>H<sub>5</sub>NHCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N) (<b>1</b>) afforded the first example of bisamido lanthanide complexes having the neutral pyrrole η<sup>5</sup>-bonded to the metal formulated as [η<sup>5</sup>:η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]­Ln­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub> (Ln = La (<b>2</b>) and Nd (<b>3</b>)). Reaction of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Sm­(μ-Cl)­Li­(THF)<sub>3</sub> with 2 equiv of <b>1</b> produced the complex [η<sup>5</sup>:η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]­[η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]]­SmN­(SiMe<sub>3</sub>)<sub>2</sub> (<b>4</b>). Treatment of <b>3</b> with 2 equiv of <b>1</b> gave the sandwich neodymium complex [η<sup>5</sup>:η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]<sub>2</sub>Nd­[η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)] (<b>5</b>), in which two neutral pyrroles bonded with metal in an η<sup>5</sup> mode. Complex <b>5</b> could also be prepared by reaction of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Nd­(μ-Cl)­Li­(THF)<sub>3</sub> with 3 equiv of <b>1</b>. Reactivities of the lanthanide bisamido complexes were further investigated. Reaction of complex <b>2</b> with pyrrolyl-functionalized imine [2-(2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>NCH)­C<sub>4</sub>H<sub>3</sub>NH] afforded a mixed η<sup>5</sup>-bonded neutral pyrrole and η<sup>1</sup>-bonded anionic pyrrolyl lanthanum complex [η<sup>5</sup>:η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]­{η<sup>1</sup>-2-[(2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)­NCH]­C<sub>4</sub>H<sub>3</sub>N}­La­[N­(SiMe<sub>3</sub>)<sub>2</sub>] (<b>6</b>). Reactions of complexes <b>2</b> and <b>3</b> with pyrrolyl-functionalized secondary amine afforded the mixed η<sup>5</sup>-bonded neutral pyrrole and the η<sup>1</sup>-bonded anionic pyrrolyl lanthanide complexes [η<sup>5</sup>:η<sup>1</sup>-(<i>N</i>-C<sub>6</sub>H<sub>5</sub>NCH<sub>2</sub>CH<sub>2</sub>)­(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)]­[(η<sup>1</sup>-2-<sup><i>t</i></sup>BuNCH)­C<sub>4</sub>H<sub>3</sub>N]<sub>2</sub>Ln (Ln = La (<b>7</b>), Nd (<b>8</b>)) with dehydrogenation of the secondary amine. Investigation of the catalytic properties of complexes <b>2</b>–<b>8</b> indicated that all complexes exhibited a high activity with a high chemo- and regioselectivity on the addition of dialkyl phosphite to α,β-unsaturated carbonyl derivatives. An interesting result was found that 1,2-hydrophosphonylation substrates could be catalytically converted to 1,4-hydrophosphinylation products when the substrates are the substituted benzylideneacetones by controlling the reaction conditions

    Lanthanide Amido Complexes Incorporating Amino-Coordinate-Lithium Bridged Bis(indolyl) Ligands: Synthesis, Characterization, and Catalysis for Hydrophosphonylation of Aldehydes and Aldimines

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    Two series of new lanthanide amido complexes supported by bis­(indolyl) ligands with amino-coordinate-lithium as a bridge were synthesized and characterized. The interactions of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Ln<sup>III</sup>(μ-Cl)­Li­(THF)<sub>3</sub> with 2 equiv of 3-(CyNHCH<sub>2</sub>)­C<sub>8</sub>H<sub>5</sub>NH in toluene produced the amino-coordinate-lithium bridged bis­(indolyl) lanthanide amides [μ-{[η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-3-(CyNHCH<sub>2</sub>)­Ind]<sub>2</sub>Li}­Ln­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub>] (Cy = cyclohexyl, Ind = Indolyl, Ln = Sm (<b>1</b>), Eu (<b>2</b>), Dy (<b>3</b>), Yb (<b>4</b>)) in good yields. Treatment of [μ-{[η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-3-(CyNHCH<sub>2</sub>)­Ind]<sub>2</sub>Li}­Ln­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub>] with THF gave new lanthanide amido complexes [μ-{[η<sup>1</sup>:η<sup>1</sup>-3-(CyNHCH<sub>2</sub>)­Ind]<sub>2</sub>Li­(THF)}­Ln­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub>] (Ln = Eu (<b>5</b>), Dy (<b>6</b>), Yb (<b>7</b>)), which can be transferred to amido complexes <b>2</b>, <b>3</b>, and <b>4</b> by reflux the corresponding complexes in toluene. Thus, two series of rare-earth-metal amides could be reciprocally transformed easily by merely changing the solvent in the reactions. All new complexes <b>1</b>–<b>7</b> are fully characterized including X-ray structural determination. The catalytic activities of these new lanthanide amido complexes for hydrophosphonylation of both aromatic and aliphatic aldehydes and various substituted aldimines were explored. The results indicated that these complexes displayed a high catalytic activity for the C–P bond formation with employment of low catalyst loadings (0.1 mol % for aldehydes and 1 mol % for aldimines) under mild conditions. Thus, it provides a convenient way to prepare both α-hydroxy and α-amino phosphonates

    Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

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    A series of lanthanide amido complexes incorporating a neutral pyrrole ligand were synthesized and characterized, and their catalytic activities were studied. Treatment of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>­Ln­(μ-Cl)­Li­(THF)<sub>3</sub> with 1 equiv of [(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)­CH<sub>2</sub>CH<sub>2</sub>] <sub>2</sub>NH (<b>1</b>) in toluene afforded the corresponding lanthanide amides with the formula [η<sup>5</sup>:η<sup>1</sup>-(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)­CH<sub>2</sub>CH<sub>2</sub>]<sub>2</sub>­NLn­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub> (Ln = La (<b>2</b>), Nd (<b>3</b>)). Reaction of <b>2</b> or <b>3</b> with <i>N</i>,<i>N</i>′-dicyclo­hexyl­carbo­diimide (CyNCNCy) gave the carbodiimide selectively inserted into the appended Ln–N bond products formulated as CyNC­{[<i>N</i>,<i>N</i>-(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)­CH<sub>2</sub>CH<sub>2</sub>]<sub>2</sub>N}­NCyLn­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub> (Ln = La (<b>4</b>), Nd (<b>5</b>)). Reactions of the lanthanide amides with Me<sub>3</sub>SiCN were also examined. A mixed reaction of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>­La­(μ-Cl)­Li­(THF)<sub>3</sub>, [(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N)­CH<sub>2</sub>CH<sub>2</sub>]<sub>2</sub>NH (<b>1</b>), and Me<sub>3</sub>SiCN in toluene at room temperature produced the novel cyano bridged dinuclear lanthanum complex η<sup>5</sup>:η<sup>1</sup>:η<sup>3</sup>-[(2,5- Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>N­CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>N]­La­[N­(SiMe<sub>3</sub>)<sub>2</sub>]­(μ-CN)­La­[N­(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub> (<b>6</b>). The stoichiometric reactions of lanthanide amides <b>2</b> or <b>3</b> with Me<sub>3</sub>SiCN produced the novel trinuclear lanthanum and neodymium complexes {(η<sup>5</sup>:η<sup>1</sup>-[(2,5-Me<sub>2</sub>C<sub>4</sub>H<sub>2</sub>­NCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>N]­Ln­[N­(SiMe<sub>3</sub>)<sub>2</sub>]­(μ-CN)}<sub>3</sub> (Ln = La (<b>7</b>), Nd (<b>8</b>)) through selective σ-bond metathesis reaction of the terminal Ln–N (N­(SiMe<sub>3</sub>)<sub>2</sub>) bond with the Si–C bond of Me<sub>3</sub>SiCN. On the basis of the stoichiometric reactions of complexes <b>2</b>, or <b>3</b> with Me<sub>3</sub>SiCN, complexes <b>2</b>, <b>3</b>, <b>4</b>, <b>5</b>, <b>7</b>, and <b>8</b> as catalysts for cyanosilylation of ketones were investigated. Results indicated that these complexes displayed a high catalytic activity on addition of Me<sub>3</sub>SiCN to ketones, and the activity of the complexes has the order of <b>7</b> ∼ <b>8</b> > <b>2</b> ∼ <b>3</b> ∼ <b>4 ∼ <b>5</b></b>. Thus, complex <b>7</b> or <b>8</b> was proposed as the active catalyst in the catalytic reaction for the precatalysts of <b>2</b> and <b>3</b>

    Synthesis and Characterization of Organolanthanide Complexes with a Calix[4]-pyrrolyl Ligand and Their Catalytic Activities toward Hydrophosphonylation of Aldehydes and Unactivated Ketones

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    The alkali metal salt free dinuclear trivalent lanthanide amido complexes (η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Et<sub>8</sub>-calix­[4]-pyrrolyl)­{LnN­(SiMe<sub>3</sub>)<sub>2</sub>}<sub>2</sub> (Ln = Nd (<b>2</b>), Sm (<b>3</b>), Gd (<b>4</b>)) were prepared through the silylamine elimination reactions of calix[4]-pyrrole [Et<sub>2</sub>C­(C<sub>4</sub>H<sub>2</sub>NH)]<sub>4</sub> (<b>1</b>) with 2 equiv of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Ln­(μ-Cl)­Li­(THF)<sub>3</sub> (Ln = Nd, Sm, Gd) in toluene at 110 °C. The complexes were fully characterized by elemental, spectroscopic, and single-crystal X-ray analyses. Studies on the catalytic activity of the new lanthanide amido complexes revealed that these complexes can be used as efficient catalysts for hydrophosphonylation of aldehydes and unactivated ketones, affording the products in high yields by employing a low catalyst loading (0.1 mol %) at room temperature in a short time (20 min). Noteworthy is that it is the first application of calix[4]-pyrrolyl-supported lanthanide amides as catalysts to catalyze the hydrophosphonylation of aldehydes and unactivated ketones under mild conditions

    Synthesis and Characterization of Organolanthanide Complexes with a Calix[4]-pyrrolyl Ligand and Their Catalytic Activities toward Hydrophosphonylation of Aldehydes and Unactivated Ketones

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    The alkali metal salt free dinuclear trivalent lanthanide amido complexes (η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Et<sub>8</sub>-calix­[4]-pyrrolyl)­{LnN­(SiMe<sub>3</sub>)<sub>2</sub>}<sub>2</sub> (Ln = Nd (<b>2</b>), Sm (<b>3</b>), Gd (<b>4</b>)) were prepared through the silylamine elimination reactions of calix[4]-pyrrole [Et<sub>2</sub>C­(C<sub>4</sub>H<sub>2</sub>NH)]<sub>4</sub> (<b>1</b>) with 2 equiv of [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>Ln­(μ-Cl)­Li­(THF)<sub>3</sub> (Ln = Nd, Sm, Gd) in toluene at 110 °C. The complexes were fully characterized by elemental, spectroscopic, and single-crystal X-ray analyses. Studies on the catalytic activity of the new lanthanide amido complexes revealed that these complexes can be used as efficient catalysts for hydrophosphonylation of aldehydes and unactivated ketones, affording the products in high yields by employing a low catalyst loading (0.1 mol %) at room temperature in a short time (20 min). Noteworthy is that it is the first application of calix[4]-pyrrolyl-supported lanthanide amides as catalysts to catalyze the hydrophosphonylation of aldehydes and unactivated ketones under mild conditions
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