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“Long-Range” Metal−Ligand Cooperation in H 2 Activation and Ammonia-Promoted Hydride Transfer with a Ruthenium−Acridine Pincer Complex

2010; American Chemical Society; Volume: 132; Issue: 42 Linguagem: Inglês

10.1021/ja107770y

1943-2984

Chidambaram Gunanathan, Boopathy Gnanaprakasam, Mark A. Iron, Linda J. W. Shimon, David Milstein,

Catalytic Cross-Coupling Reactions

The acridine-based pincer complex 1 exhibits an unprecedented mode of metal−ligand cooperation involving a "long-range" interaction between the distal acridine C9 position and the metal center. Reaction of 1 with H2/KOH results in H2 splitting between the Ru center and C9 with concomitant dearomatization of the acridine moiety. DFT calculations show that this process involves the formation of a Ru dihydride intermediate bearing a bent acridine ligand in which C9 is in close proximity to a hydride ligand followed by through-space hydride transfer. Ammonia induces transfer of a hydride from the Ru center of 1 to C9 of the flexible acridine pincer ligand, forming an unusual dearomatized fac-acridine PNP complex.