Insertion of CO2, Isocyanates, and Acetonitrile into the P–Si Bond of a Silyl-Substituted N‑Heterocyclic Carbene Phosphinidene

TL;DR

This paper explores how a specific chemical compound reacts with CO2, isocyanates, and acetonitrile, revealing different reaction pathways and products.

Contribution

The study identifies new reactivity patterns and product formation mechanisms involving a silyl-substituted phosphinidene.

Findings

CO2 and phenyl isocyanate insert into the P–Si bond readily.

Acetonitrile activation requires a frustrated Lewis pair pathway with group 13 halides.

Aluminum halides produce different products depending on the Lewis acid used.

Abstract

This work investigates the reactivity of IDippP-SiMe3 (IDipp = 1,3-bis­(2,6-diisopropylphenyl)-imidazolin-2-ylidene)
toward
CO2, Ph-NCO, and Me-CN. Whereas carbon dioxide and phenyl
isocyanate readily insert into the polarized P–Si bond, the
activation of acetonitrile only proceeds via a frustrated Lewis pair
(FLP) pathway in the presence of group 13 halides. Nitrile insertion
in the presence of aluminum halides affords both an N-heterocyclic carbene phosphinidene (NHCP)-substituted imine and
a phosphaalkene, with the product ratio depending on the choice of
Lewis acid. In contrast, the addition of BCl2

m
Ter (
m
Ter = 2,6-(2,4,6-methyl-C6H2)-C6H3) selectively affords
an NHCP-substituted imine via dehalosilylation.

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