Transition metal coordination polymers with polycarboxylic acid as bridging ligands:: Synthesis and structure characterization of [Fe(μ4-bta)0.5(phen)(OH)]n

A new 2D (two-dimensional) coordination polymer, [Fe(mu(4)-bta)(0.5)(phen)(OH)](n) (1), has been hydrothermally synthesized with FeCl3 . 6H(2)O, Na(4)bta (H(4)bta = 1,2,4,5-benzentetracarboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P2(1)/n space group, a = 1.0129(2) nm, b = 0.9265(2) nm, c = 1.5696(3) nm, beta = 91.37(3)degrees, V= 1.4721(5) nm(3), Z = 3, final R-1 = 0.0292, wR(2) = 0.0798 for 2572 [l > 2sigma (l)] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four Fe-III, forming a new mu(4)-coordination mode. Four deprotonated carboxylic groups of bta link to Fe-III ions alternatively through monodentate and bidentate coordination fashion, constructing 2D layer network. The measurement of variable temperature magnetic susceptibility indicates that there exist antiferromagnetic interactions between Fe-III ions in the compound. The TGA spectrum displays relatively fine thermal stability of the compound. In addition, IR and UV-Vis spectra of compound 1 have also been measured.