Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][MII(H2O)6](SO4)2, (MII = Mn, Fe, Co, Ni)

Abstract

A series of novel organically templated metal sulfates, [C₅H₁₄N₂][M^II(H₂O)₆](SO₄)₂ with (M^II = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2₁/n for (1, 3) and P2₁/c for (2,4). Crystal data are as follows: [C₅H₁₄N₂][Mn(H₂O)₆](SO₄)₂, a = 6.6385(10) Å, b = 11.0448(2) Å, c = 12.6418(2) Å, β = 101.903(10)°, V = 906.98(3) ų, Z = 2; [C₅H₁₄N₂][Fe(H₂O)₆](SO₄)₂, a = 10.9273(2) Å, b = 7.8620(10) Å, c = 11.7845(3) Å, β = 116.733(10)°, V = 904.20(3) ų, Z = 2; [C₅H₁₄N₂][Co(H₂O)₆](SO₄)₂, a = 6.5710(2) Å, b = 10.9078(3) Å, c = 12.5518(3) Å, β = 101.547(2)°, V = 881.44(4) ų, Z = 2; [C₅H₁₄N₂][Ni(H₂O)₆](SO₄)₂, a = 10.8328(2) Å, b = 7.8443(10) Å, c = 11.6790(2) Å, β = 116.826(10)°, V = 885.63(2) ų, Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M^II(H₂O)₆]²⁺ and [C₅H₁₄N₂]²⁺ cations and (SO₄)²⁻ anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M^II = Fe, Co, Ni respectively) exhibit single ion anisotropy.