Accessing Five- and Seven-Membered Phosphorus-Based Heterocycles via Cycloaddition Reactions of Azophosphines

Heterocycles containing both phosphorus and nitrogen have seen increasing use in recent years in luminescent materials, coordination chemistry and building blocks for inorganic polymers, yet their chemistry is currently dominated by five- and six-memberd derivatives. Seven-membered P/N heterocycles are comparatively scarce and lack general, high yielding syntheses. We explore the synthesis and characterisation of 1,2,5-diazaphosphepines from azophosphines. The mechanism has been probed in detail with both computational and experimental studies supporting a stepwise mechanism to form a five-membered ring, and subsequent ring expansion to the diazaphosphepine. Regioselective synthesis of five- and seven-membered rings is possible using asymmetric alkynes. The Lewis acidic borane B(C6F5)3 could either catalyse the formation of the seven-membered ring (iPr derivative) or trap out a key intermediate via a frustrated Lewis pair (FLP) mechanism (tBu derivative)

Synthesis and Reactivity of the [NCCCO]– Cyanoketenate Anion

Cyanoketene is a fundamental molecule that is actively being searched for in the interstellar medium. Its deprotonated form (cyanoketenate) is a heterocumulene that is isoelectronic to carbon suboxide whose structure has been the subject of debate. These research questions are hampered by a lack of useful synthetic pathways to these molecules. We report the first synthesis of the cyanoketenate anion in [K(18-crown-6)][NCCCO] (1) as a stable molecule on a multigram scale in excellent yields (>90%). The structure of this molecule is probed crystallographically and computationally. We also explore the protonation of 1, and its reaction with triphenylsilylchloride and carbon dioxide. In all cases, anionic dimers are formed. The cyanoketene could be synthesized and crystallographically characterized when stabilized by a N-heterocyclic carbene. The cyanoketenate is a very useful unsaturated building block containing N, C and O atoms that can now be explored with relative ease and will undoubtedly unlock more interesting reactivity

Parallels between Metal-Ligand Cooperativity and Frustrated Lewis Pairs

Peer reviewe

Azophosphines:Synthesis, Structure and Coordination Chemistry

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues

Synthesis and Reactivity of the [NCCCO]⁻ Cyanoketenate Anion

Cyanoketene is a fundamental molecule that is actively being searched for in the interstellar medium. Its deprotonated form (cyanoketenate) is a heterocumulene that is isoelectronic to carbon suboxide whose structure has been the subject of debate. However, the investigation of cyanoketene and its derivatives is hampered by the lack of practical synthetic routes to these compounds. We report the first synthesis of the cyanoketenate anion in [K(18‐crown‐6)][NCCCO] (1) as a stable molecule on a multigram scale in excellent yields (>90 %). The structure of this molecule is probed crystallographically and computationally. We also explore the protonation of 1, and its reaction with triphenylsilylchloride and carbon dioxide. In all cases, anionic dimers are formed. The cyanoketene could be synthesized and crystallographically characterized when stabilized by a N‐heterocyclic carbene. The cyanoketenate is a very useful unsaturated building block containing N, C and O atoms that can now be explored with relative ease and will undoubtedly unlock more interesting reactivity

Synthesis and Reactivity of the [NCCCO]⁻ Cyanoketenate Anion

Cyanoketene is a fundamental molecule that is actively being searched for in the interstellar medium. Its deprotonated form (cyanoketenate) is a heterocumulene that is isoelectronic to carbon suboxide whose structure has been the subject of debate. However, the investigation of cyanoketene and its derivatives is hampered by the lack of practical synthetic routes to these compounds. We report the first synthesis of the cyanoketenate anion in [K(18‐crown‐6)][NCCCO] (1) as a stable molecule on a multigram scale in excellent yields (>90 %). The structure of this molecule is probed crystallographically and computationally. We also explore the protonation of 1, and its reaction with triphenylsilylchloride and carbon dioxide. In all cases, anionic dimers are formed. The cyanoketene could be synthesized and crystallographically characterized when stabilized by a N‐heterocyclic carbene. The cyanoketenate is a very useful unsaturated building block containing N, C and O atoms that can now be explored with relative ease and will undoubtedly unlock more interesting reactivity

Exploiting the Brønsted acidity of phosphinecarboxamides for the synthesis of new phosphides and phosphines

International audienc

Azophosphines:Synthesis, Structure and Coordination Chemistry

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues.</p