A heptadentate ligand possessing two phenol groups: Its diverse coordination chemistry and the catalytic behaviors of its transition complexes towards benzene oxidation

Amide bond cleavage initiated by coordination with transition metal ions and tuned by an auxiliary ligand

To scission effectively an amide bond, it is essential for a metal centre to bind to the amide bond and the metal centre is of sufficient Lewis acidity which can be tuned by auxiliary ligands.

Crystal structure of bis(bis{(E)-[(6-{(E)-[(4-fluorobenzyl)imino]methyl}pyridin-2-yl)methylidene](4-fluorophenyl)amine}nickel(II)) tetra-bromide nona-hydrate

In the title complex, [Ni(C21H17F2N3)2]2Br4·9H2O, there are two independent metal complexes per asymmetric unit and two ligands per metal complex. The structural features (bond lengths and angles) of the two complexes are almost identical. In each complex, the nickel(II) ion is coordinated in an octa-hedral environment by six N atoms from two chelating (9E)-N-({6-[(E)-(4-fluoro-benzyl-imino)-meth-yl]pyridin-2-yl}methyl-ene)(4-fluoro-phen-yl)methanammine ligands. The Ni-N bond lengths range from 1.973 (2) to 2.169 (2) Å, while the chelate N-Ni-N angles range from 77.01 (10) to 105.89 (9)°. Additionally, there are four bromide anions and nine solvent water mol-ecules within the asymmetric unit. The water mol-ecules form a hydrogen-bonded network, displaying C-H⋯O, C-H⋯Br, O-H⋯Br, O-H⋯O and O-H⋯F inter-actions into layers parallel to (111). In each unit, the fluoro-phenyl rings of one ligand are stacked with the central ring of the other ligand via π-π inter-actions, with the closest centroid-to-plane distances being 3.445 (5), 3.636 (5), 3.397 (5) and 3.396 (5) Å.

Synthesis and characterization of copper(ii) complexes with multidentate ligands as catalysts for the direct hydroxylation of benzene to phenol

Like iron(iii) complexes, copper(ii) complexes catalyse the direct hydroxylation of benzene to phenol with H₂O₂ as the oxidant and their catalytic efficiency correlates with the reduction potentials of the copper(ii) complexes.