Steric control of 4-connected network topology in hydrogen bonded coordination polymers

Two 1D coordination polymers of copper(II) acetylenedicarboxylate, [Cu(O2CCCCO2)(C5H5N)(2)(MeOH)] (1) and [Cu(O2CCCCO2)(Me2C5H3N)(2)(MeOH)]center dot MeOH(2), have been synthesised and structurally characterised by single crystal X-ray diffraction. In both cases the square pyramidal Cu II atoms have trans coordinated pyridyl ligands and trans eta(1) carboxylates in the equatorial sites with methanol occupying the apical position. The linear dicarboxylate ligand results in the formation of near linear coordination polymers. The polymeric chains in 1 form 2D hydrogen bonded (4,4) sheets whereas in 2 this topology is not possible, due to the extra steric bulk of the pyridine methyl groups, and a 3D hydrogen bonded network with CdSO4 (cds) topology is formed in which the lattice methanol molecules are also incorporated into the hydrogen bonding bridges.