Structural and Magnetic Properties of One-Dimensional Squarate Bridged Coordination Polymers Containing 2-Aminomethylpyridine Ligand

Three novel one-dimensional (1D) coordination polymers with general formula {[M(mu-sq)(2)(amp)(2)]center dot H2O}(n) [M=Cu(II) (1), Zn(II) (2)] and [Cd(mu-sq)(2)(amp)(2)](n) (3) [sq: Squarate; amp:2-aminomethylpyridine] have been prepared and spectroscopically studied. Each metal (II) ion in 1-3 is octahedrally coordinated by two sq and two amp ligands. The amp ligands are N,N' coordinated, while the sq ligands bridge the metal centers forming 1D linear chain structure. The individual chains are linked by O-H center dot center dot center dot O hydrogen bonds involving the hydrogens of water molecules (1-2), amino hydrogens and squarate O atoms (1-3). The hydrogen bonded layers are further assembled into three-dimensional supramolecular networks by weak aromatic pi-pi interactions. EPR results indicate that the ground state of the paramagnetic electron in 1 and Cu2+ doped complexes 2-3 is d(x)2 (-y)2. Magnetic measurements reveal that complex 1 shows paramagnetic behavior.