Facile Preparation of a Scandium Terminal Imido Complex
Supported by a Phosphazene Ligand
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Abstract
The
scandium bis(alkyl) complex bearing the phosphazene ligand
L<sup>1</sup>Sc(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub> (<b>1</b>) (L<sup>1</sup> = N(PPh<sub>2</sub>NPh)<sub>2</sub>) reacted with an equimolar amount of 2,6-diisopropylaniline to afford
the corresponding mixed alkyl/anilido complex L<sup>1</sup>Sc[NHC<sub>6</sub>H<sub>3</sub>(<sup><i>i</i></sup>Pr)<sub>2</sub>](CH<sub>2</sub>SiMe<sub>3</sub>) (<b>2</b>). Under mild conditions
(20 °C, 4 h or 0 °C, 12 h), complex <b>2</b> could
be swiftly transformed to the terminal imido complex L<sup>1</sup>ScN[C<sub>6</sub>H<sub>3</sub>(<sup><i>i</i></sup>Pr)<sub>2</sub>](DMAP)<sub>2</sub> (<b>4</b>) in the presence
of DMAP (DMAP = 4-<i>N,N</i>-dimethylaminopyridine). Correspondingly,
treatment of the yttrium and lutetium bis(alkyl) complexes L<sup>2</sup>Ln(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub> (L<sup>2</sup> = N[Ph<sub>2</sub>PNC<sub>6</sub>H<sub>3</sub>(<sup><i>i</i></sup>Pr)<sub>2</sub>]<sub>2</sub>; Ln = Y (<b>7</b>), Lu (<b>8</b>)) with equimolar amounts of 2,6-diisopropylaniline gave
the mixed alkyl/anilido complexes L<sup>2</sup>Ln[NHC<sub>6</sub>H<sub>3</sub>(<sup><i>i</i></sup>Pr)<sub>2</sub>](CH<sub>2</sub>SiMe<sub>3</sub>) (Ln = Y (<b>9</b>), Lu (<b>10</b>)),
which, however, underwent dealkylation of the Ln–CH<sub>2</sub>SiMe<sub>3</sub> species at temperatures of 60 °C for <b>9</b> and 100 °C for <b>10</b> to afford bis(anilido)
complexes L<sup>2</sup>Ln[NHC<sub>6</sub>H<sub>3</sub>(<sup><i>i</i></sup>Pr)<sub>2</sub>]<sub>2</sub> (Ln = Y (<b>11</b>), Lu (<b>12</b>)) as redistribution products. All these complexes
have been characterized by <sup>1</sup>H, <sup>13</sup>C{<sup>1</sup>H}, and <sup>31</sup>P{<sup>1</sup>H} NMR spectroscopy and X-ray
diffraction analyses, and clear structural insight into the behavior
of an imido functionality on a lanthanide metal center was provided
