Structure of di(salicylaldehyde benzoylhydrazonato) zinc (II), an unusual staircase polymeric structure formed via E → Z isomerization on complexation

Abstract

Abstract A bicomplex of salicylaldehyde benzoylhydrazone (SBH) with Zn(II) was synthesized in ethanol and single crystals were obtained in DMSO. The compound crystallizes in the orthorhombic system with the space group Pna21(33) and crystal data: a = 22.573(3)Å, b = 6.1208(5) Å, c = 17.881(2) Å, V = 2470.5(5) Å3, Z = 4, d(calc) = 1.462 g⋅cm–3, (2633 reflections with I > 2 σ(I); final R = 0.0509; R w = 0.1099). The asymmetric unit is a nearly planar bicomplex built up from one Zn atom linked to two monodeprotonated SBH ligands. The compound can be described as formed of chains extended along the b axis. This linear polymeric character results from the linking of each asymmetric unit to two neighbouring ones via four (2x2) covalent Zn-O bonds involving three Zn atoms and four phenolic oxygens. These covalent bonds are related to the very unusual Z configuration of the ligand. The three-dimensional cohesion of the compound is obtained by van der Waals forces be-tween the polymeric chains.