Controlled Synthesis of Racemic Indenyl Rare-Earth Metal Complexes via the Cooperation between the Intramolecular Coordination of Donor Atoms and a Bridge

Abstract

The reactions of Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>6</sub>CH<sub>2</sub>CH<sub>2</sub>-DG)<sub>2</sub> (DG = NMe<sub>2</sub> (<b>1</b>), CH<sub>2</sub>NMe<sub>2</sub> (<b>2</b>), OMe (<b>3</b>), and N­(CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>O (<b>4</b>)) with [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>3</sub>RE­(μ-Cl)­Li­(THF)<sub>3</sub> in toluene afforded a series of racemic divalent rare-earth metal complexes: {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>-DG)<sub>2</sub>}­RE (DG = NMe<sub>2</sub>, RE = Yb (<b>6</b>) and Eu (<b>7</b>); DG = CH<sub>2</sub>NMe<sub>2</sub>, RE = Yb (<b>8</b>), Eu (<b>9</b>), and Sm (<b>10</b>); DG = OMe, RE = Yb (<b>11</b>) and Eu (<b>12</b>); DG = N­(CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>O, RE = Yb (<b>13</b>) and Eu (<b>14</b>)). Similarly, the racemic divalent rare-earth metal complexes {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>OMe)}­RE (RE = Yb (<b>15</b>) and Eu (<b>16</b>)) were also obtained. The reaction of Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>OMe)<sub>2</sub>Li<sub>2</sub> with NdCl<sub>3</sub> gave a racemic dimeric neodymium chloride {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>OMe)<sub>2</sub>NdCl}<sub>2</sub> (<b>17</b>), whereas the reaction of Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)<sub>2</sub>Li<sub>2</sub> with SmCl<sub>3</sub> afforded a racemic dinuclear samarium chloride bridged by lithium chloride {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)<sub>2</sub>SmCl}<sub>2</sub>(μ-LiCl) (<b>18</b>). Further reaction of complex <b>18</b> with LiCH<sub>2</sub>SiMe<sub>3</sub> provided an unexpected rare-earth metal alkyl complex {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>:σ-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)­[(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>N­(CH<sub>2</sub>)­Me]}­Sm (<b>19</b>) through the activation of an sp<sup>3</sup> C–H bond α-adjacent to the nitrogen atom. Complexes <b>19</b> and {η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>:σ-Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)­[(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>N­(CH<sub>2</sub>)­Me]}Y (<b>20</b>) were also obtained by one-pot reactions of Me<sub>2</sub>Si­(C<sub>9</sub>H<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>)<sub>2</sub>Li<sub>2</sub> with RECl<sub>3</sub> followed by treatment with LiCH<sub>2</sub>SiMe<sub>3</sub>. All compounds were fully characterized by spectroscopic methods and elemental analysis. Complexes <b>6</b>–<b>10</b> and <b>14</b>–<b>20</b> were further characterized by single-crystal X-ray diffraction analysis. All of the prepared rare-earth metal complexes were racemic, suggesting that racemic organo rare-earth metal complexes could be controllably synthesized by the cooperation between a bridge and the intramolecular coordination of donor atoms

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