η<sup>3</sup>‑Silaallyl/Alkenylsilyl
Molybdenum Complex: Synthesis, Structure, and Reactivity toward Primary
Amines To Form Mo–N–Si Three-Membered Cyclic Complexes
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Abstract
The new η<sup>3</sup>-silaallyl/alkenylsilyl
molybdenum complex
Cp*Mo(CO)<sub>2</sub>(η<sup>3</sup>-Ph<sub>2</sub>SiCHCMe<sub>2</sub>) (<b>3</b>) was synthesized by the reaction of Cp*Mo(CO)<sub>2</sub>(py)Me with Ph<sub>2</sub>HSiCHCMe<sub>2</sub>. Reactions
of <b>3</b> with primary amines RNH<sub>2</sub> (R = <sup><i>t</i></sup>Bu, <sup><i>i</i></sup>Pr, Et) gave Mo–N–Si
three-membered cyclic complexes Cp*Mo(CO)<sub>2</sub>(κ<sup>2</sup>-<i>N</i>,<i>Si</i>-RHNSiPh<sub>2</sub>) (<b>5a</b>, R = <sup><i>t</i></sup>Bu; <b>5b</b>, R = <sup><i>i</i></sup>Pr; <b>5c</b>, R = Et) with
elimination of isobutene. In NMR tube reactions using <sup><i>i</i></sup>PrNH<sub>2</sub> and EtNH<sub>2</sub>, the Mo–N–Si–C
four-membered cyclic complexes Cp*Mo(CO)<sub>2</sub>(κ<sup>2</sup>-<i>N</i>,<i>C</i>-RHNSiPh<sub>2</sub>CH<sup><i>i</i></sup>Pr) (<b>4b</b>, R = <sup><i>i</i></sup>Pr; <b>4c</b>, R = Et) were observed as intermediates
leading to <b>5b</b> and <b>5c</b>, respectively. Complex <b>4c</b> was successfully isolated in a preparative reaction. The
molecular structures of <b>3</b>, <b>4c</b>, and <b>5b</b> were determined by X-ray crystal analyses. Interestingly,
the contribution of silylene character was suggested for the SiPh<sub>2</sub> moiety of <b>5b</b> from the X-ray structure. The reaction
of <b>5b</b> with MeOH gave the dinuclear complex Cp*(CO)<sub>2</sub>Mo(μ-OMe)(μ-H)Mo(CO)<sub>2</sub>Cp* as a major
product