Amine-templated linear vanadium sulfates with different chain structures

Abstract

Amine-templated vanadium sulfates of the formula [HN(CH₂)₆NH][(V^IVO)₂(OH)₂(SO₄)₂]·H₂O, I, [H₃N(CH₂)₂NH₃][V^III(OH)(SO₄)₂]·H₂O, II, and [H₂N(CH₂)₄NH₂][(V^IVO)(H₂O)(SO₄)₂], III, have been prepared under hydrothermal conditions. These vanadium sulfates add to the new emerging family of organically templated metal sulfates. Compound I has a linear chain structure consisting of V₂O₈ square-pyramid dimers connected by corner-sharing SO₄ tetrahedra, creating four-membered rings along the chain. Both II and III possess simple linear chain topologies formed by VO₆ octahedra and SO₄ tetrahedra, with II having the tancoite chain structure. Compound I crystallizes in the triclinic space group P↑ (No. 2) with a=7.4852(4) Å, b=9.5373(5) Å, c=11.9177(6) Å, α=77.22°, β=76.47(2)°, γ=80.86°, Z=2. Compound II: monoclinic, space group P2₁/c (No. 14), a=6.942(2) Å, b=10.317(3) Å, c=15.102(6) Å, β=90.64(4)°, Z=4. Compound III: triclinic, space group P↑ (No. 2) with a=6.2558(10) Å, b=7.0663(14) Å, c=15.592(4) Å, α=90.46(2)°, β=90.47(2)°, γ=115.68(2)°, Z=2. Magnetic susceptibility measurements reveal weak antiferromagnetic interactions in I and III and ferromagnetic interactions in II.