Synthesis, X-ray structure, and magnetic properties of interconnected ferromagnetic molecular bowls by hydrogen bonds

Abstract

Ferromagnetic molecular bowls, [(μ 3-OH)Cu 3(L)]Cl 0.5(ClO 4) 4.5·1.5H 2O ( A), were interconnected by the hydrogen bonding interactions with sodium 1,3,5-benzenetricarboxylate (Na 3BTC), and a dimer of molecular bowl {[Cu 3(L)(μ 3-OH)] 2(C 9H 3O 6)}(ClO 4) 6·Cl·8H 2O ( 1) was isolated. In the structure, two molecular bowls are connected to a BTC 3− ion via the μ 3-hydroxo groups by the hydrogen-bonding interactions, which gives rise to a Y-shaped nano-sized molecule (12.1×19.1×19.9 Å 3). Each molecular bowl in 1 shows similar bond distances and angles to those of A, especially around the Cu II ions and the central oxygen atom. Variable temperature magnetic susceptibility data indicate that compound 1 has magnetic parameters of g=2.03, J=37.8 cm −1 and zJ′=−0.50 cm −1 and R=1.54×10 −5. Three Cu(II) ions within a molecular bowl exhibit relatively strong ferromagnetic interaction, but a weak antiferromagnetic interaction occurs between the two Cu 3 units connected to a BTC 3−.