Yttrium Hydride Complex
Bearing CpPN/Amidinate Heteroleptic Ligands: Synthesis,
Structure, and Reactivity
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Abstract
The reaction of the yttrium dialkyls (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)Y(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf) (<b>1</b>) with an excess
of <i>N</i>,<i>N′</i>-diisopropylcarbodiimide
gave
the yttrium monoalkyl complex (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)Y(CH<sub>2</sub>SiMe<sub>3</sub>)[<sup><i>i</i></sup>PrNC(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr] (<b>2</b>). <b>2</b> subsequently
reacted with 1 equiv of PhSiH<sub>3</sub> to generate the CpPN/amidinate
heteroleptic yttrium hydride {(C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)Y[<sup><i>i</i></sup>PrNC(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr](μ-H)}<sub>2</sub> (<b>3</b>). Hydride <b>3</b> showed good reactivity
toward various substrates containing unsaturated C–C, C–N,
and N–N bonds, such as azobenzene, <i>p</i>-tolyacetylene,
1,4-bis(trimethylsilyl)-1,3-butanediyne, <i>N</i>,<i>N′</i>-diisopropylcarbodiimide, and 4-dimethylaminopyridine,
affording the yttrium hydrazide complex <b>4</b> with a rare
η<sup>2</sup>-Cp bonding mode, yttrium terminal alkynyl complex <b>5</b>, yttrium η<sup>3</sup>-propargyl complex <b>6</b>, yttrium amidinate complex <b>7</b>, and yttrium 2-hydro-4-dimethylaminopyridyl
product <b>8</b>, respectively
