A four-membered heterocyclic prevented biradical that can be described as a zwitterion or masked N-heterocyclic phosphinidene

Abstract

Heterocyclobutane-1,3-diyls bridge the gap between organic and inorganic chemistry and are known for the majority of group 13–15 elements. The kinetically stabilized compounds have been employed in the activation of small molecules, akin to conventional transition metal complexes, and are thus cost-efficient alternatives for future processes. Here, we present the synthesis and characterization of a particularly unusual example of a heterocyclobutane-1,3-diyl, [RC(μ-NR′)2P], that blurs the line between biradical, zwitterion, and phosphinidene. While the reaction with AuCl and an NHC (N-heterocyclic carbene) shows resemblance to biradicals, the reaction with an alkyne to form a phosphirene is characteristic for phosphinidenes. Quantum chemical investigations allow for the classification of the amidinate-based heterocycle [RC(μ-NR′)2P] next to comparable literature examples.