Facile Cleavage of the P=P Double Bond in Vinyl‐Substituted Diphosphenes

• Published in: Angewandte Chemie International Edition Vol. 58; no. 1; pp. 273 - 277
• Main Authors: Liu, Liu Leo, Cao, Levy L., Zhou, Jiliang, Stephan, Douglas W.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 02.01.2019; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Cations; Chemistry; Chemistry, Multidisciplinary; Cleavage; Dimerization; diphosphenes; N-heterocyclic olefins; P=P bonds; Phosphaalkynes; phosphinium; phosphirene; Phosphorus; Physical Sciences; Science & Technology; Substitutes; P=P bonds; N-HETEROCYCLIC CARBENE; CONJUGATED POLYMERS; diphosphenes; X-RAY-STRUCTURE; COMPLEXES; CHEMISTRY; phosphirene; phosphinium; MULTIPLE BONDS; N-heterocyclic olefins
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201812592

The reactions of the cyclic alkyl amino carbene (CAAC) 1 with phosphaalkynes generate the kinetically unstable CAAC‐derived phosphirenes 4 and 5, which undergo rearrangement/dimerization reactions to give the vinyl‐substituted diphosphenes 2, 3, and 6. The P=P double bond scission of 2 or 3 is unprecedentedly effected by S8, [AuCl(tht)], or MeOTf at room temperature, which affords a dithiophosphorane 7, a phosphepine Au complex 8, or phosphepinium cations 9 and 10, respectively. The cationic species feature little homoaromaticity while representing the first examples of the phosphorus‐containing analogue of the tropylium ion. Quite labile P=P double bonds: Vinyl‐substituted diphosphenes featuring small HOMO–LUMO gaps undergo a facile P=P double bond cleavage, leading to a series of novel vinyl‐substituted phosphorus derivatives.