9. "Palladium-Catalyzed Phosphaketene Decarbonylation: Diphosphaureylene Intermediates in Diphosphene Formation," Marie-Anne David, Denyce K. Wicht, David S. Glueck, Louise M. Liable-Sands, Glenn P. A. Yap, and Arnold L. Rheingold, Organometallics 1997, 16, 4768-4770.
Pd(PPh3)4-catalyzed decarbonylation of the phosphaketene Mes*PCO [1, Mes* = 2,4,6-(t-Bu)3C6H2] gives the diphosphene Mes*P=PMes* (2). Related reactions of 1 with zerovalent Pd and Pt phosphine complexes afford diphosphaureylene complexes ML2[Mes*PC(O)PMes*] (L 2 = chelating diphosphine), whose structure and properties depend markedly on the metal and ancillary ligands; Pd(dppf)[Mes*PC(O)PMes*] [12, dppf = 1,1'-bis(diphenylphosphino)ferrocene] also catalyzes decarbonylation of 1. A mechanism for the catalysis in which diphosphaureylene intermediates form 2 and CO by P-P reductive elimination from Pd(II) is proposed.