Reactivity of Pyridine-2,4,6-tricarboxylic Acid toward Zn(II) Salts under Different Reaction Conditions

Pyridine-2,4,6-tricarboxylic acid (ptcH3) readily reacts with a Zn(II)
salt at room temperature to form different products depending upon
the presence or absence of pyridine in the reaction mixture. In
the presence of pyridine, the ligand breaks to form infinitely zigzag
coordination polymers with the empirical formula {Zn(Ox)(py)2}n
(Ox = oxalate, py = pyridine). The backbone is formed from Zn(II)−oxalate where two pyridine molecules are coordinated to each
Zn(II) ion giving it hexacoordination. The orientation of the bound
pyridines is slightly different when Zn(II)−nitrate is used compared
to that when Zn(II)−sulfate (or acetate) salt is used. In absence of
pyridine, the ligand remains intact and forms a mixture of a
carboxylate-bridged coordination polymer and a discrete carboxylate-bridged 12-membered metallomacrocycle.