208759-92-6Relevant articles and documents
The palladium-catalyzed carbonylation of nitrobenzene into phenyl isocyanate: The structural characterization of a metallacylic intermediate
Paul, Frédéric,Fischer, Jean,Ochsenbein, Philippe,Osborn, John A.
, p. 2199 - 2206 (2008/10/08)
The synthesis and characterization of a family of metallacyclic complexes of palladium, that is, (N-N)PdC(O)ON(Ar′)C(O), are reported where N-N is a diimine ligand and Ar′ is a substituted aryl. The complexes were isolated from solutions during the catalytic carbonylation of nitroaromatics using palladium complexes and were proposed to be intermediates in the catalytic process. The X-ray structure determination of [(tBu)2bipy]PdC(O)ON[p-C6H4-( tBu)]C(O) ((tBu)2bipy = 4,4′-bis-tert-butyl-2,2′-bipyridyl) was carried out, the complex crystallizing in the triclinic space group P1 (C30H37N3O3Pd) 2·C3H6O, Z = 2, a = 15.626(4) A?, b = 18.269(6) A?, c = 12.067(3) A?, α = 107.34(2)°, β = 111.53(2)°, γ = 78.81(2)°. The crystal structure contains two molecules in the asymmetric unit which are assembled in a quasidimeric form via stacking interactions. The previously assigned metallacyclic structure for these complexes was confirmed. A mechanistic pathway for the carbonylation process implicating a series of metallacycle intermediates is proposed without intervention of a metal-imido intermediate. Thermal decomposition studies of the metallacycle and some trapping experiments are also presented.
