Abstract
Cu(II) compounds of pyridine-2,6-dicarboxylic acid with meta-substituted pyridines as additional ligands are reported. Two compounds are mononuclear and one is polynuclear with bridging, 3-(hydroxymethyl)pyridine. The compounds are characterised by XRD, IR, EPR and ligand field spectroscopy. Hydrogen bonding has an important role in the crystal packing.
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► Three new Cu(II) compounds with the dianion of pyridine-2,6-dicarboxylic acid are reported. ► 3-Acetylpyridine and 3-hydroxypyridine act as monodentate ligands to Cu via N. ► 3-(Hydroxymethyl)pyridine acts as a bridging ligand between two Cu ions using N and OH.
Three new Cu(II) compounds of pyridine-2,6-dicarboxylic acid (H
2pdc) with meta-substituted pyridines as additional ligands have been synthesized and structurally characterised using X-ray diffraction. Two of them are mononuclear compounds, i.e. [Cu(pdc)(3acpyr)(H
2O)] (
1) (3acpyr
=
3-acetylpyridine) and [Cu(pdc)(3HOp)(H
2O)](H
2O)
2 (
2) (3HOp
=
3-hydroxypyridine). The third compound is polynuclear, i.e. [Cu(pdc)(μ-3HOmp-κN,O)]
n
(
3) (3HOmp
=
3-(hydroxymethyl)pyridine). The three compounds are also characterised by IR, EPR and ligand field spectroscopy. The geometry around the Cu(II) ions is distorted square pyramidal for compounds
1 and
2 and distorted octahedral for compound
3. The lattice of compound
1 is organised by an intra-sheet hydrogen-bond pattern generating double layers. Compound
2 has a lattice arranged by the two water molecules in the lattice with complicated 2D O–H⋯O intra-sheet hydrogen bonding motifs.
The zig-zag chains in compound
3 are further organised in layers, due to the axial coordination at Cu(II), forming a so-called (4,
3) ladder-like one-dimensional coordination polymer. These ladders are interconnected by hydrogen bonding.