Robust building blocks for inorganic crystal engineering

We have prepared two ligands, 4- and 5-carboxylic acid pyrimidine, and synthesized and crystallographically characterized seven coordination complexes thereof. The need for potentially structurally disruptive counterions is eliminated by deprotonation of the carboxylic acid moieties; the carboxylates present in each structure act as counterions and balance the charge on the divalent metal ions leading to charge-neutral complex ions. The four new M(II)-complexes with 4-carboxylic acid pyrimidine (M = Ni, Cu, Zn, and Co) are isostructural as are the three M(II) complexes with 3-carboxylic acid pyrimidine (M = Ni, Cu, and Zn), indicating robust and reliable coordination modes for both ligands.