Two-dimensional oxalate-bridged heterometallic coordination polymer: Crystal structure and thermal behavior of [NaCr(pyim)(ox)_2(H_2O)] centre dot 2H_2O(pyim = 2-(2'-pyridyl)imidazole)

摘要

A new coordination polymer of formula [NaCr(pyim)(ox)_2(H_2O)] centre dot 2H_2O(pyim = 2-(2'-pyridyl)imidazole,ox = oxalate)has been prepared and it revealed a novel two-dimensional framework generating from the oxalate-bridged heterometallic Cr~(III)-Na~I helical chains with alternative P/M arrangement.Within the 2-D layer,a regular alternation of the metal centers is interconnected by two types of oxalate dianions in common bis(bidentate)ligand and an unusual asymmetric monodentate bonding mode towards a sodium atom of a neighboring chain.The thermal behavior of the complex showed that the lattice and coordinated water molecules to Na~+ were lost at low temperature,and that the resulting anhydrous [NaCr(pyim)(ox)_2] is thermally stable at 633 K.