Related Experiment Video
Updated: May 24, 2026

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)
Published on: November 22, 2016
Synthesis, reactivity, and computational analysis of halophosphines supported by dianionic guanidinate ligands
Allison L Brazeau1, Mikko M Hänninen, Heikki M Tuononen
1Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151 Richmond Street, London, N6A 5B7 Ontario, Canada.
Abstract:
The reported chemistry and reactivity of guanidinate supported group 15 elements in the +3 oxidation state, particularly phosphorus, is limited when compared to their ubiquity in supporting metallic elements across the periodic table. We have synthesized a series of chlorophosphines utilizing homo- and heteroleptic (dianionic)guanidinates and have completed a comprehensive study of their reactivity. Most notable is the reluctancy of these four-membered rings to form the corresponding N-heterocyclic phosphenium cations, the tendency to chemically and thermally eliminate carbodiimide, and the scarcely observed ring expansion by insertion of a chloro(imino)phosphine into a P-N bond of the P-N-C-N framework. Computational analysis has provided corroborating evidence for the unwillingness of the halide abstraction reaction by demonstrating the exceptional electron acceptor properties of the target phosphenium cations and the underscoring strength of the P-X bond.
Related Concept Videos
Diazonium Group Substitution: –OH and –H
ortho–para-Directing Deactivators: Halogens
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
