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Novel Lanthanide Amides Incorporating Neutral Pyrrole Ligand in a Constrained Geometry Architecture: Synthesis, Characterization, Reaction, and Catalytic Activity
Abstract
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>NCH)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- Dataset
- Dataset
- Biophysics
- Biochemistry
- Cell Biology
- Immunology
- Cancer
- Hematology
- Chemical Sciences not elsewhere classified
- 2C
- 3Si
- lanthanide amido complexes
- Constrained Geometry Architecture
- Novel Lanthanide Amides Incorporating Neutral Pyrrole Ligand
- pyrrole
- 2 equiv
- 6H
- lanthanide bisamido complexes
- bisamido lanthanide complexes
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Last time updated on 12/02/2018
This paper was published in The Francis Crick Institute.
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