Switchable Reactivities of Metalated Phosphasilenes Regulated by Reversible 1,2‐Metal Migration

TL;DR

Scientists discovered a new way to create and transform phosphasilenes, which can act as silylene equivalents through reversible metal migration.

Contribution

A novel synthetic strategy for P-metalated and Si-metalated phosphasilenes with distinct reactivity profiles is introduced.

Findings

P-metalated phosphasilenes show strong π-bonding in Si═P linkages and react with inert molecules.

Si-metalated phosphasilenes behave as silylene equivalents via retro-1,2-metal migration.

Transmetallation with dimetal carbonyl complexes expands the Si-metalated phosphasilene family.

Abstract

Anionic reagents with silicon‐containing double bonds, M(R)Si═ERn (E = main group elements), have garnered significant interest owing to their unique metal‐mediated reactivity and their potential in transferring the Si═E unit. Within this domain, the intriguing field of Si‐metalated phosphasilenes remains uncharted. Herein, we present a novel strategy for the efficient synthesis of P‐metalated phosphasilenes and their subsequent transformation into Si‐metalated phosphasilenes via a distinctive phosphinosilylene intermediate formed during a metal‐mediated skeletal rearrangement. While P‐metalated phosphasilenes exhibit a pronounced π‐bonding character in the Si═P linkage, the skeletal rearrangement attenuates both the Si═P and Si─M bonds in the resulting Si‐metalated phosphasilenes, rendering them effective silylene equivalents. Moreover, formal transmetallation of Si‐metalated phosphasilene with dimetal carbonyl complexes provides access to a broader array of Si‐metalated analogues. This transmetallation proceeds through the phosphinosilylene intermediate, as evidenced by the isolation of a silylene–dimanganese complex, thereby revealing an uncharted mechanistic manifold for this class of transformations.

We develop novel strategies for the facile synthesis of anionic phosphasilenes in the forms of both P‐metalation and Si‐metalation. The P‐metalated phosphasilene displays a pronounced π‐bond‐driven reactivity toward robust inert molecules, whereas the Si‐metalated analogue behaves as a silylene equivalent via a retro‐1,2‐silver migration.

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