Coordination polymer with a staircase molecular architecture: Connecting binuclear Zn(II) bis-chelate platforms with bridging 4,4′-bipyridyl

Abstract

A new tetraketone ligand with two separated β-diketone functions was prepared, 1,3-[CO-CH2-COC(CH3)2OCH3]2Ph (H2L iPrOMe). The title coordination polymer, [Zn2(L iPrOMe)2(DMSO)2(bipy)]n (DMSO = dimethylsulfoxide; bipy = 4,4′-bipyridyl), formed as the only crystalline product upon interaction of Zn(II) acetate, H2L iPrOMe and bipy in 1:1:1 to 1:1:5 molar ratios in DMSO as a solvent. A single crystal XRD study of the compound revealed a staircase polymeric architecture of the complex. The architecture is based on binuclear ′Zn2(L iPrOMe)2′ platforms where each Zn(II) cation is chelated by two β-diketonate groups of two L iPrOMe ligands in the equatorial plane, while each L iPrOMe ligand chelates two Zn(II) cations. The coordination environment of each Zn(II) is completed to a distorted octahedron by an O atom of a terminal DMSO and an N atom of bridging bipy ligands. The resulting staircase polymeric ribbons are packed in a self-inclusion mode as would be expected for van der Waals interactions. Most fragments of the molecule were found to be disordered over two equally populated orientations, which was interpreted as evidence of a modulated structure. In addition, several fragments reveal additional minor disordering and high thermal motion.