Varying the secondary coordination sphere: synthesis of cobalt and iron complexes of a tripodal ligand featuring two hydrogen-bond donors or acceptors

Abstract

In order to further understand the role of the secondary coordination sphere in biomimetic systems, a series of cobalt(II) and iron(II) complexes bearing the non-heme bis(5-cyclohexyliminopyrrol-2-ylmethyl)-2-pyridylmethylamine (^PyN(pi^Cy)₂) ligand were synthesized. This platform, based on the tris(5-cyclohexylimino-pyrrol-2-ylmethyl)amine (N(pi^Cy)₃) platform, reduces the number of possible hydrogen-bonding interactions from three (in N(pi^Cy)₃) to two, while maintaining the ability of the ligand to datively coordinate to a metal center. The secondary coordination spheres of the family of dative and anionic cobalt(II) and iron(II) complexes were characterized in the solid-state using X-ray crystallography and IR spectroscopy. Moreover, oxidation of an iron(II) complex was explored to compare its reactivity to that of the analogous iron(II) complex of the N(pi^Cy)₃ platform.

GRAPHICAL ABSTRACT

Keywords:

• Cobalt
• iron
• manganese
• hydrogen-bonding ligand
• tautomerization
• oxygen activation

Disclosure statement

There are no conflicts to declare.

Additional information

Funding

This work was support by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division under award DE-SC-0016026. ARF is a Sloan Research Fellow and a Camille Dreyfus Teacher-Scholar. TJM acknowledges support from the National Science Foundation Graduate Research Fellowship Program under grant no. DGE-1144245.