Synthesis and structural characterisation of two coordination polymers (molecular ladders) incorporating [M(OAc)2]2 secondary building units and 4,4′-bipyridine [M = Cu(ii), Zn(ii)]

Abstract

We report herein the synthesis and structural characterisation of two coordination polymers: {[Cu(4,4′-bipy)(OAc)₂]·2.5H₂O}_n1 and {[Zn(4,4′-bipy)(OAc)₂]}_n2, which feature dissimilar dimeric metal acetate secondary building units linked through 4,4′-bipyridine to yield 1D molecular ladders. In 1, the ladders connect via (C–H⋯O) hydrogen bonds to generate 2D sheets, which further link via (C–H⋯π) hydrogen bonds to give a 3D supramolecular network. A 3D network in 2 results directly from a combination of (C–H⋯O) and (C–H⋯π) hydrogen bonding. Variable temperature magnetic susceptibility measurements reveal very weak antiferromagnetic coupling between Cu(II) centres across the acetato bridges in 1 (J = −1.18 cm⁻¹).