Phosphinoborylenes as stable sources of fleeting borylenes |
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Authors: | Conor Pranckevicius Marco Weber Ivo Krummenacher Ashwini K Phukan Holger Braunschweig |
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Institution: | Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg Germany.; Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg Germany ; Department of Chemical Sciences, Tezpur University, Napaam, 784028 India |
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Abstract: | Base-stabilised borylenes that mimic the ability of transition metals to bind and activate inert substrates have attracted significant attention in recent years. However, such species are typically highly reactive and fleeting, and often cannot be isolated at ambient temperature. Herein, we describe a readily accessible trimethylphosphine-stabilised borylborylene which was found to possess a labile P–B bond that reversibly cleaves upon gentle heating. Exchange of the labile phosphine with other nucleophiles (CO, isocyanide, 4-dimethylaminopyridine) was investigated, and the binding strength of a range of potential borylene “ligands” has been evaluated computationally. The room-temperature-stable PMe3-bound borylenes were subsequently applied to novel bond activations including 2 + 2] cycloaddition with carbodiimides and the reduction of dichalcogenides, revealing that PMe3-stabilised borylenes can effectively behave as stable sources of the analogous fleeting dicoordinate species under mild conditions.A room-temperature stable phosphinoborylene provides a source of a reactive two-coordinate borylene via dissociation of a labile phosphine upon gentle heating. Ligand exchange, the capture of unsaturated molecules, and oxidation have been explored. |
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