The title dinuclear mercury(II) complex, [Hg2Cl4(C16H19N3)2], synthesized from the pyridine-derived Schiff base (E)-N 1,N 1-diethyl-N 4-[(pyridin-2-yl)methyl­idene]benzene-1,4-di­amine (DPMBD), has inversion symmetry with the five-coordinated HgII centres having distorted square-pyramidal stereochemistry comprising two N-atom donors from a bidentate chelate BPMBD ligand and three Cl-atom donors, one monodentate and two bridging.

In the title Schiff base compound, C26H22N4O2, the hydroxy group forms a intramolecular hydrogen bond to the imine N atom and generates anS(6) ring motif. The conformation about the C=N and N=N bonds isE. The 4-methoxybenzene ring and thep-phenylenediamine ring are inclined to the phenol ring by 11.61 (17) and 46.04 (17)°, respectively. The terminalN-phenyl ring is inclined to thep-phenylenediamine ring by 50.72 (17)°. In the crystal, adjacent molecules are linked by C—H...O hydrogen bonds, involving thep-phenylenediamine ring and the phenol ring, forming chains along [001]. The chains are linked by a number of C—H...π interactions, forming slabs propagating parallel to (100).

The mononuclear discrete complex [Cu(pivHA)2] contains two pivaloyl hydroxamates (pivHA−) coordinated to a copper(II) ion in a centrosymmetric trans mode through hydroxamate and carbonyl O atoms. The copper(II) O4 coordination is square planar.