Crystal Structure and Magnetic Properties of an Oxygen-Bridged Trinuclear Copper(II) Complex

Abstract

[Cu3 (L)3].3(C1O4) (LH = l,3-diaminopropan-2-ol) was synthesized and its crystal structure determined. It crystallizes in the triclinic space group P1̅ with a = 10.504(2), b = 10.856(2), c = 12.519(2) Å, a = 74.41(1), ß = 70.60(1), γ = 63.60(1)°, V = 1193.6(3) Å3, Z = 2. The structure consists of trimeric [Cu3(L)3]+3 units and three perchlorate anions in the asymmetric unit. In the compound three copper(II) ions are linked by 1,3-diamino-2-propanol molecules in such a way that an almost equilateral triangle is formed. The coordination spheres of the three copper(II) ions are slightly different from each other. The coordination geometry of Cu1 is a distorted square pyramid, and that of Cu2 is almost square planar while that of Cu3 is tetrahedrally distorted square planar. The copper(II) centers are separated by average 3.481(2) Å and antiferromagnetically coupled (-J = 100 cm-1), which follows from temperature- dependent magnetic susceptibility measurements in the temperature range 4.4 to 299 K. The average Cu-O-Cu angle is 128.1(1)° in the super-exchange pathway. As the temperature is increased, the magnetic moment rises from 1.41 μB at 4.4 K to 2.22 μB at 299 K. In the X(T ) curve no characteristic maximum was observed. The magnetic super-exchange interaction for the title compound is due to the effective overlap of the magnetic orbitals (dx²-y²) with orbitals of bridging alkoxide oxygen atoms