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(μ4-bta)0.5(phen)(OH)]n (1), has been hydrothermally synthesized with FeCI3·6H2O, Na4bta (H4bta = 1,2,4,5-benzentetra-carboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.0129(2) nm, b=0.9265(2) nm, c=1.5696(3) nm,β=91.37(3)°, V= 1.4721(5) nm3, Z= 3, final R1 = 0.0292, wR2= 0.0798 for 2572 [l> 2σ (l)] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four Fe|||, forming a new μ4-coordination mode. Four deprotonated carboxylic groups of bta link to Fe||| 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||| ions in the compound. The TGA spectrum displays relatively fine thermal stability of the co