Ag(I) and Tl(I) Precursors as Transfer Agents of a Pyrrole-Based Pincer Ligand to Late Transition Metals

A PNP ligand, PN^pyrP ((PN^pyrP)H = 2,5-bis­((di-<i>iso</i>-propylphosphino)­methyl)­pyrrole), which employs a pyrrole unit as a central anionic nitrogen donor, was designed. The corresponding group 10 metal chlorides as well as iridium and ruthenium compounds were isolated. In order to conduct this work, [(PN^pyrP)­Tl] and [(PN^pyrP)­Ag]₂ were synthesized and characterized. The thallium and silver species were paramount in the formation of the iridium and ruthenium complexes, which could not be isolated using (PN^pyrP)H or the corresponding lithium pyrrolide salt. Interestingly, the solid state molecular structure of [(PN^pyrP)­Tl] indicates that the metal center engages in an η² intermolecular interaction with the backbone of a neighboring pyrrole molecule instead of the expected bonding to the phosphine arms