Oxygen-Induced Dimerization of Alkyl-Manganese(II) 2,6-Bisiminopyridine Complexes: Selective Synthesis of a New Ditopic NNN-Pincer Ligand

The outcome of the
reaction of manganese­(II) dialkyls with 2,6-bisiminopyridine
(BIP) ligands is dramatically altered by the presence of very small
amounts of oxygen (<0.5 mol %), leading to binuclear species. These
arise from the dimerization of the initial product, a Mn­(II) 4-alkyl-2,6-bisimino-dihydropyridinate
alkyl complex. Cleavage of the binuclear Mn products with methanol
affords the free dimeric bases, which can be regarded as a special
type of ditopic NNN pincer ligand with an unusual tricyclic framework.
The coordinative ability of the new ligands has been probed with the
syntheses of Zn and Pd organometallic derivatives.