Baya Miguel, Houghton Jennifer, Konya Denes, Champouret Yohan, Daran Jean-Claude, Almeida Leñero Karina Q, Schoon Lodewijk, Mul Wilhelmus P, van Oort A Bart, Meijboom Nicolaas, Drent Eite, Orpen A Guy, Poli Rinaldo
Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l'Université Paul Sabatier et à l'Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France.
J Am Chem Soc. 2008 Aug 13;130(32):10612-24. doi: 10.1021/ja8012903. Epub 2008 Jul 16.
Reduction of compound "Pd(bcope)(OTf)2" [bcope = (c-C8H14-1,5)PCH2CH2P(c-C8H14-1,5); OTf = O3SCF3] with H2/CO yields a mixture of Pd(I) compounds Pd2(bcope)2(CO)22 (1) and Pd2(bcope)2(mu-CO)(mu-H) (2), whereas reduction with H2 or Ph3SiH in the absence of CO leads to Pd3(bcope)3(mu3-H)22 (3). Exposure of 3 to CO leads to 1 and 2. The structures of 1 and 3 have been determined by X-ray diffraction. Complex Pd2(bcope)2(CO)2 displays a metal-metal bonded structure with a square planar environment for the Pd atoms and terminally bonded CO ligands and is fluxional in solution. DFT calculations aid the interpretation of this fluxional behavior as resulting from an intramolecular exchange of the two inequivalent P atom positions via a symmetric bis-CO-bridged intermediate. A cyclic voltammetric investigation reveals a very complex redox behavior for the "Pd(bcope)(OTf)2"/CO system and suggests possible pathways leading to the formation of the various observed products, as well as their relationship with the active species of the PdL2(2+)/CO/H2-catalyzed oxo processes (L2 = diphosphine ligands).
