Synthesis of pyridine-alkoxide ligands for formation of polynuclear complexes

We have prepared and characterized a series of novel polydentate N,O-donor ligands derived from our well-studied ligand 2-(2-pyridinyl)-2-propanol (pyalkH), having the general formula Me{C(OH)(2-py)CH2}(n)H, where n = 2 or 3. Like pyalkH, these analogues bind via N and O with deprotonation at the latter, thus extending the strongly donor pyridine-alkoxide chelation power of pyalkH to polydentate forms. The greater denticity allows for more effective binding and polynuclear cluster formation with first-row transition metals. Several stable alkoxo-bridged polynuclear clusters of these ligands with Mn, Cu, Co and Ni have been prepared; all reported ligands and complexes have been characterized, including by X-ray crystallography. We report a one-step synthesis of these ligands, alongside pyalkH, on a multigram scale from inexpensive starting materials. We have also developed a new scalable procedure for the isolation of pyalkH that avoids the need for chromatography, making large-scale production of this ligand commercially viable.