The first 2-pyridylmethyl pendant armed ethylene cross-bridged cyclam ligand has been synthesized and successfully complexed to Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+ cations. X-ray crystal structures were obtained for all six complexes and demonstrate pentadentate binding of the ligand with the requisite cis-V configuration of the cross-bridged cyclam ring in all cases, leaving a potential labile binding site cis to the pyridine donor for interaction of the complex with oxidants and/or substrates. The electronic properties of the complexes were evaluated using solid state magnetic moment determination and acetonitrile solution electronic spectroscopy, which both agree with the crystal structure determination of high spin divalent metal complexes in all cases. Cyclic voltammetry in acetonitrile revealed reversible redox processes in all but the Ni2+ complex, suggesting catalytic reactivity involving electron transfer processes are possible for complexes of this ligand. Screening for oxidation catalysis using hydrogen peroxide as the terminal oxidant for the most biologically relevant Mn2+, Fe2+, and Cu2+ complexes identified the Mn2+ and Fe2+ complexes as potential oxidation catalysts worthy of continued development.

Synthesis, structural studies, and oxidation catalysis of the late first row transition metal complexes of a 2-pyridylmethyl pendant armed ethylene cross-bridged cyclam

249th National Meeting (2015)

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