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

A PNP ligand, PNpyrP ((PNpyrP)H = 2,5-bis­((di-iso-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, [(PNpyrP)­Tl]
and [(PNpyrP)­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
(PNpyrP)H or the corresponding lithium pyrrolide salt.
Interestingly, the solid state molecular structure of [(PNpyrP)­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.