A P−P Bond as a Redox Reservoir and an Active Reaction Site

• Published in: Angewandte Chemie International Edition Vol. 57; no. 43; pp. 14159 - 14163
• Main Authors: Kim, Yeong‐Eun, Lee, Yunho
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 22.10.2018; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: carbonylation; Carbonyls; Chemistry; Chemistry, Multidisciplinary; Isocyanates; metal radicaloids; metal–ligand cooperation; Nickel; Phosphides; phosphorus complexes; Physical Sciences; Science & Technology; Silver chloride; Spectroscopy; IMIDO COMPLEXES; nickel; metal radicaloids; MECHANISM; CRYSTAL-STRUCTURE; MEDIATED FORMATION; INTERCONVERSION; metal-ligand cooperation; PERSISTENT PHOSPHINYL RADICALS; LIGANDS; O-2; DIPHOSPHINE; GENERATION; phosphorus complexes; carbonylation
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201809122

The carbonylation of a nickel(II) anilido species 2 led to the formation of a dinickel(0)–CO complex (P2P‐PP2){Ni(CO)}2 3 with a P−P bond along with isocyanate generation. In this reaction, the central phosphide moiety of an anionic PPP ligand (PPP−=−P[2‐PiPr2C6H4]2) acts as a single‐electron donor to form a P radical. Alternatively, 3 can be synthesized from the reduction of (PPP)NiCl (1) in the presence of CO; thus, the reaction proceeds by radical coupling of a .P−Ni0−CO species. The reverse reaction occurred to generate 1 when 3 was treated with AgCl. Since the P−P bond is light‐sensitive, its homolysis is possible and was explored by EPR spectroscopy and DFT analysis. Finally, various bond‐activation reactions of 3 occurred under visible‐light conditions, thus indicating that a P−P bond can act as an active reaction site. Weigh up the options: A P−P moiety within a dinickel complex showed dual functionality as a redox center and a reaction site. Reversible electron exchange between Ni and P produced a P−P single bond, and its homolysis led to unique open‐shell reactivity (see picture).