Dual Reactivity of a Geometrically Constrained Phosphenium Cation. (27th July 2022)

• Record Type: Journal Article
• Authors: Volodarsky, Solomon; Bawari, Deependra; Dobrovetsky, Roman
• Is Part Of: Angewandte Chemie. Volume 134:Number 36(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-27
• Subjects: Phosphenium Cation -- Phosphinidene -- Phosphorus -- Silane -- Small Molecule Activation; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202208401
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: A geometrically constrained phosphenium cation in bis(pyrrolyl)pyridine based NNN pincer type ligand (1 + ) was synthesized, isolated and its preliminary reactivity was studied with small molecules. 1 + reacts with MeOH and Et2 NH, activating the O−H and N−H bonds via a P‐center/ligand assisted path. The reaction of 1 + with one equiv. of H3 NBH3 leads to its dehydrogenation producing 5 . Interestingly, reaction of 1 + with an excess H3 NBH3 leads to phosphinidene (P I ) species coordinating to two BH3 molecules (6 ). In contrast, [1 + ][OTf] reacts with Et3 SiH by hydride abstraction yielding 1‐H and Et3 SiOTf, while [1 + ][B(C6 F5 )4 ] reacts with Et3 SiH via an oxidative addition type reaction of Si−H bond to P‐center, affording a new P V compound (8 ). However, 8 is not stable over time and degrades to a complex mixture of compounds in matter of minutes. Despite this, the ability of [1 + ][B(C6 F5 )4 ] to activate Si−H bond could still be tested in catalytic hydrosilylation of benzaldehyde, where 1 + closely mimics transition metal behaviour. Abstract : Geometrically constrained phosphenium cation 1 + was synthesized and its reactivity was studied. While 1 + reacts with MeOH and Et2 NH via P‐center/ligand assisted path, its reaction with Et3 SiH proceeds via oxidative addition type reaction affording new P V intermediate. The ability of 1 + to activate Si−H bond was tested in catalytic hydrosilylation of benzaldehyde, where 1 + closely mimics transition metal behaviour.