An ethylene cross-bridged pentaazamacrocycle and its Cu complex: constrained ligand topology and excellent kinetic stability.

Rigid and topologically constrained ethylene cross-bridged tetraazamacrocycles have been increasingly utilised for thirty years as they form remarkably stable transition metal complexes for catalysis, biomedical imaging, and inorganic drug molecule applications. Extending these benefits to pentaazamacrocycles has been achieved and a first transition metal complex prepared and structurally characterized.

Synthesis, structural studies, and oxidation catalysis of the manganese(II), iron(II), and copper(II) complexes of a 2-pyridylmethyl pendant armed side-bridged cyclam.

The first 2-pyridylmethyl pendant armed structurally reinforced cyclam ligand has been synthesized and successfully complexed to Mn, Fe, and Cu cations. X-ray crystal structures were obtained for the diprotonated ligand and its Cu complex demonstrating pentadentate binding of the ligand with configuration of the side-bridged cyclam ring, leaving a potential labile binding site to the pyridine donor for interaction of the complex with oxidants and/or substrates. The electronic properties of these complexes were determined by means of solid state magnetic moment, with a low value of μ = 3.

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

The first 2-pyridylmethyl pendant-armed ethylene cross-bridged cyclam ligand has been synthesized and successfully complexed to Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+) 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.