Synthesis and characterization of bis-tridentate group 12 perchlorate complexes of bis(2-pyridylmethyl) ether

Abstract

Bis-tridentate chelates of Zn(ClO4)2, Cd(ClO4)2, and Hg(ClO4)2 with two equivalents of bis(2-pyridylmethyl) ether (L1) were isolated. The complexes were characterized using X-ray crystallography, IR, 1H NMR, and TGA. Isomorphs [Zn(L1)2](ClO4)2·CH3CN (1·CH3CN) and [Cd(L1)2](ClO4)2·CH3CN (2·CH3CN) crystallized in the monoclinic space group P21 with meridional octahedral geometry. [Hg(L1)2](ClO4)2 (3) crystallized in the monoclinic space group P21/c with approximately C2 symmetric trigonal prismatic geometry. Proton NMR of 3 at −40 °C revealed heteronuclear JHgH coupling yet lacked the geminal splitting of methylene protons expected from the solid-state structure suggesting equivalence through intramolecular reorganization was rapid relative to the NMR time scale. The complexes are compared to other bis-tridentate chelates of bis(2-pyridylmethyl) ligands with the central oxygen of L1 replaced by other heteroatoms.