Among the most important donor ligands in transition-metal chemistry are pyridine-type ligands, 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) in particular. The reactivity of these ligands upon coordination to transition metals has not been well-studied. Specifically, nucleophilic additions to the pyridyl ring of transition-metal-coordinated bipy or phen have not been reported.

Julio Pérez and colleagues, Universidad de Oviedo, Spain, have investigated various nucleophilic additions to rhenium-coordinated phen and bipy. Using the complex Re(CO)₃(x)(PMe₃)]OTf (x = phen or bipy), inter- and intramolecular additions were found. Upon reacting the phen complex with KN(SiMe₃)₂, which is usually non-nucleophilic in nature, this amide reversibly adds to the phen ligand leading to the intramolecular addition of the PMe₃ ligand to phen.

Intermolecular additions were also found by reacting the Re complex, bearing either a phen or a bipy ligand, with MeLi. Interestingly, the amide was found to reversibly undergo addition, whereas MeLi reacted irreversibly. These reactions contribute to the range of possible reactivity pathways for such phen- and bipy-containing transition-metal complexes, providing insight into their deactivation in related studies.

• Nucleophilic Additions to Coordinated 1,10-Phenanthroline: Intramolecular, Intermolecular, Reversible, and Irreversible,
  Rebeca Arévalo, M. Isabel Menéndez, Ramón López, Isabel Merino, Lucía Riera, Julio Pérez,
  Chem. Eur. J. 2016.
  DOI: 10.1002/chem.201604438