Inorganic Chemistry, Vol.44, No.9, 3330-3336, 2005
Syntheses, crystal structures, and magnetic properties of novel manganese(II) complexes with flexible tripodal ligand 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene
Two novel metal-organic frameworks (MOFs)-[Mn(titmb)(N-3)(2)]center dot 1.5H(2)O (1) and [Mn-3(titmb)2(C2O4)(3)(H2O)]center dot 10H(2)O (2)-were obtained by reactions of the flexible tripodal ligand 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) with Mn(OAc)(2)center dot 4H(2)O, together with NaN3 and K2C2O4, respectively. The structures of these MOFs were established by single-crystal X-ray diffraction analysis. The crystal data for 1 were as follows: monoclinic, C2/c, a = 20.956(13) angstrom, b = 9.884(6) angstrom, c = 24.318(14) angstrom, beta = 95.87(5)degrees, Z = 8. The crystal data for 2 were as follows: triclinic, P (1) over bar, a = 12.400(g) angstrom, b = 16.827(12) angstrom, c = 17.196(11) angstrom, alpha = 66.35(5), beta = 95.87(5)degrees, gamma = 71.03(6), Z = 2. Complex 1 is a novel noninterpenetrating three-dimensional (3D) framework, in which the azide ligand connects Mn-Pi atoms in an end-to-end (EE) mode to give [Mn-N-N-N-](n) infinite one-dimensional (1D) chains, and complex 2 has a two-dimensional (2D) network structure in which the Mn-Pi ions are linked by the oxalate anions to form 1D [Mn(C2O4)](n) chains. Each titmb in these two complexes connects three metal atoms and serves as a three-connecting ligand. The magnetic properties of 1 and 2 were investigated. The results showed that the antiferromagnetic interactions occurred between the Mn-Pi ions linked by the azide ligands in complex 1, and those linked by the oxalate anions and the carboxylate in syn-anti coordination mode in complex 2. The entirely different structures of complexes 1 and 2, on one hand, indicate that the azide and the oxalate ligands affected the structures of MOFs greatly, and on the other hand, reveals the potential applications of MOFs with the azide and oxalate ligands, which are efficient magnetic couplers.