Structure and physical properties of substituted malonate divalent metal coordination polymers with dipyridylamine co-ligands: acentric chain, herringbone layer, and novel binodal network topologies

Abstract

Three divalent metal coordination polymers and one molecular species containing 4,4′-dipyridylamine (dpa) and substituted malonate ligands have been prepared and structurally characterized by single crystal X-ray diffraction. The degree of substitution and different coordination environments promote significant structural diversity in this system. {[Cu(mmal)(Hmmal)(Hdpa)]·H₂O}_n (1, mmal = methylmalonate) crystallizes in an acentric space group and possesses 1-D coordination polymer chain motifs containing [Cu(OCO)]_n linkages. {[Cu₃(dmmal)₂(dpa)₃](ClO₄)₂·2H₂O}_n (2, dmmal = dimethylmalonate) manifests an unprecedented (4,5)-connected binodal network with (4⁴6²)(4⁶6⁴)₂ topology, and contains equatorial–equatorial bridged linear {Cu₃O₂} trimeric units. {[Cd₂(dmmal)₂(dpa)(Hdpa)](ClO₄)·2H₂O·CH₃CH₂OH}_n (3) displays (6,3) herringbone layers, while {[Co(dmmal)₂(Hdpa)₂]·6H₂O} (4) has co-crystallized neutral coordination complexes and hydrogen-bonded hexameric water molecule aggregations. Ultraviolet irradiation of a sample of 3 resulted in blue-violet light emission due to π–π* transitions within the dpa and Hdpa⁺ ligands. Variable temperature magnetic studies indicated antiferromagnetic coupling along the {Cu(OCO)}_n chains in 1 and within the {Cu₃O₂} linear trimers in 2.