Synthesis, Structural Characterization, and Reactivity
of Mono(amidinate) Rare-Earth-Metal Bis(aminobenzyl) Complexes
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Abstract
Three kinds of solvated lithium amidinates
with different coordination
models were obtained via recrystallization of [PhC(NC<sub>6</sub>H<sub>4</sub><sup><i>i</i></sup>Pr<sub>2</sub>-2,6)<sub>2</sub>]Li(THF) (<b>1a</b>) in different solvents. Treatment of <i>o</i>-Me<sub>2</sub>NC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>Li with LLnCl<sub>2</sub>(THF)<sub><i>n</i></sub> (<b>2</b>; L = [PhC(NC<sub>6</sub>H<sub>4</sub><sup><i>i</i></sup>Pr<sub>2</sub>-2,6)<sub>2</sub>]<sup>−</sup> (NCN<sup>dipp</sup>), [<i>o</i>-Me<sub>2</sub>NC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>C(NC<sub>6</sub>H<sub>4</sub><sup><i>i</i></sup>Pr<sub>2</sub>-2,6)<sub>2</sub>]<sup>−</sup> (NCN<sup>dipp</sup>′)) formed in situ from reaction of LnCl<sub>3</sub>(THF)<sub><i>x</i></sub> with LLi(THF) gave the rare-earth-metal
bis(aminobenzyl) complexes LLn(CH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)<sub>2</sub> (L = NCN<sup>dipp</sup>, Ln = Sc (<b>3a</b>), Y (<b>3b</b>), Lu (<b>3c</b>); L = NCN<sup>dipp</sup>′, Ln = Sc (<b>3d</b>), Lu
(<b>3e</b>)) in high yields. Reactions of complexes <b>3</b> with CO<sub>2</sub>, PhNCO, 2,6-diisopropylaniline, and S have been
explored. CO<sub>2</sub> inserted into each Ln–C bond of complexes <b>3a</b>–<b>c</b> to form the dual-core complexes [(NCN<sup>dipp</sup>)Sc(μ-η<sup>1</sup>:η<sup>1</sup>-O<sub>2</sub>CCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)<sub>2</sub>]<sub>2</sub> (<b>4a</b>) and [(NCN<sup>dipp</sup>)Ln(μ-η<sup>1</sup>:η<sup>2</sup>-O<sub>2</sub>CCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)(μ-η<sup>1</sup>:η<sup>1</sup>-O<sub>2</sub>CCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)]<sub>2</sub> (Ln = Y (<b>4b</b>), Lu (<b>4c</b>)). The reaction of <b>3b</b>,<b>c</b>,<b>e</b> with PhNCO produced LLu[OC(CH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)NPh]<sub>2</sub>(thf) (L = NCN<sup>dipp</sup>, Ln = Y (<b>5b</b>), Lu (<b>5c</b>); L = NCN<sup>dipp</sup>′, Ln = Lu (<b>5e</b>)). Protonolysis of <b>3a</b>,<b>b</b> by 2,6-diisopropylaniline formed straightforwardly
the μ<sub>2</sub>-imido complexes [(NCN<sup>dipp</sup>)Ln(μ-NC<sub>6</sub>H<sub>4</sub><sup><i>i</i></sup>Pr<sub>2</sub>-2,6)]<sub>2</sub> (Ln = Sc (<b>6a</b>), Lu (<b>6c</b>)). Reaction
of <b>3e</b> with S<sub>8</sub> afforded the sulfur insertion
products (NCN<sup>dipp</sup>′)Lu(CH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)(SCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)(thf) (<b>7e</b>) and (NCN<sup>dipp</sup>′)Lu(SCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-<i>o</i>)<sub>2</sub>(thf)<sub>2</sub> (<b>7f</b>) in high yields, respectively,
depending on the stoichiometric ratio. All of these complexes were
fully characterized by elemental analysis, NMR spectroscopy, and X-ray
structural determinations
