Two one-dimensional zinc(II) coordination polymers: catena-poly[[bis(pentane-2,4-dionato-kappa2O,O')zinc]-mu-1,4-bis(x-pyridyl)-2,3-diazabuta-1,3-diene] (x = 3, 4).

The structures of the two title isomeric compounds, [Zn(C5H7O2)2(C12H10N4)]n, are built up around two non-equivalent symmetry centres, one of them at the cation position and the other bisecting the N-N bond in the 1,4-bis(3/4-pyridyl)-2,3-diazabuta-1,3-diene (3pdb/4pdb) units. Both Zn cations have the Zn atoms an inversion centres and present tetragonally distorted octahedral environments, but differences in their linkage through the 3pdb and 4pdb ligands give rise to differently shaped weakly interacting chains.