Synthesis and structural characterization of a barium coordination polymer based on a micro sub(2) -monoatomic bridging 4-nitrobenzoate

Abstract

The synthesis, spectral characterization, crystal structure and properties of [Ba(H sub(2) O) sub(2) (NMF) sub(2) (4-nba) sub(2)], 1 (NMF = N-methylformamide; 4-nba = 4-nitrobenzoate), are reported. Sup(1) H and sup(13) C NMR spectral data reveal the presence of NMF in 1. A strong band at 1660 cm sup(-1) in the infrared spectrum indicates the binding of amide oxygen to Ba(II) which is confirmed by the single crystal structure. The unique Ba(II) in 1 situated on a mirror plane exhibits nine coordination and is bonded to two symmetry related monodentate terminal NMF ligands via the amide oxygen, and a terminal aqua ligand. The micro sub(2)-monoatomic bridging binding mode of each of a crystallographically independent 4-nba ligand and a unique water ligand link the Ba(II) cations into an infinite chain extending along a, leading to the formation of a 1D coordination polymer with Ba...Ba separations of 4.2522(3) angstrom. In the chain, the {BaO sub(9)} polyhedra are linked in a face sharing fashion. Thermal decomposition of 1 results in the formation of BaCO sub(3) residue. A comparative study of the structural chemistry of several barium coordination polymers is described.