H-bond supported coordination polymers of transition metal sulfites with different dimensionalities

Abstract

Three new transition metal–sulfite coordination complexes namely [(C₆N₄H₁₈)NaCo(SO₃)₂(H₂O)₃], (1), [(C₃N₂H₁₀)₂NaCo(SO₃)₂(H₂O)₂]·H₂O, (2), and [(C₆N₄H₁₈)Zn₃(SO₃)₃], (3), have been synthesized under hydrothermal conditions in the presence of various organic amines where the amine behaves as an organic ligand. The complexes were characterized by PXRD, TGA and FTIR techniques. 1 shows the formation of a zero dimensional structure whereas 2 and 3 show two dimensional layer structures. The difference between 1 and 2 is due to the usage of different amines. The tetradentate amine in 1 dictates the coordination of sulfite groups in a cis-manner leading to the formation of a zero dimensional structure whereas in 2 the bidentate amine forces the sulfite group coordination in a trans-manner resulting in a two dimensional structure. In 3, the tetradentate amine caps one of the Zn centres, however the other two unique zinc ions coordinate with the sulfite anion to form interconnected cyclic dimers which gives a two dimensional layer structure. The subtle changes in the hydrogen bonding pattern and its consequence on the overall lattice to give a three dimensional network for 1 and 2 and two dimensional layer structure for 3 have been emphasized in detail.