Study of the iron/trimesic acid system for the hydrothermal synthesis of hybrid materials

Two divalent iron trimesates were synthesized hydrothermally at 453 K for 72 hours under autogenous pressure using 1,3,5-benzenetricarboxylic acid (or trimesic acid, symbolized by BTC-H-3). The first one, [Fe(H2O)(4)(BTC-H-2)(2)], is molecular and crystallizes in the monoclinic space group P2(1)/c (no. 14) with cell parameters at 293 K: a = 5.1572(3) Angstrom, b = 3.0703(8) Angstrom, c = 15.2673(10) Angstrom, beta = 97.209(2)degrees, Z = 2. The second formulated [Fe-3(H2O)(12)(BTC)(2)] is one-dimensional; it crystallizes in the monoclinic space group C2 (no. 5) with the following cell parameters at 293 K: a = 17.5592(4) Angstrom, b = 12.9874(2) Angstrom, c = 6.6031(1), beta = 112.004(1)degrees, Z = 2. Its structure is based on isolated undulating chains which are organized in such a way that they seem to built sheets. Mossbauer spectrometry confirmed the presence of two divalent iron sites in agreement with crystallographic results and also that this compound remains paramagnetic till 4.2 K.