Synthesis, Crystal Structures and Magnetic Properties of Two Methoxo-Bridged Dimeric Copper(II) Complexes [Cu 2(APMD)4(μ2-OMe) 2 ]X 2(APMD = 2-aminopyrimidine; X = BF4 or CIO4)

Two bis-methoxo-bridged dimeric copper(II) complexes, [Cu2(OMe)2(APMD)4](BF4)2 1 and [Cu2(OMe)2(APMD)4](ClO4)2 2, were prepared and characterized by x-ray single-crystal structure analysis and magnetic susceptibility. Complexes 1 and 2 are isomorphous, being composed of discrete [Cu2( w 2-OMe)2(APMD)4]2+ cations and anions with each Cu(II) atom ligated by two pyrimidine nitrogen atoms (Cu-N , 2.01Å) from two APMD ligands and two oxygen atoms (Cu-O , 1.92Å) from the w 2 -methoxo groups in a distorted square-planar geometry. The intramolecular metal-metal separations in the two complexes are ca. 2.95 Å. The intermediate antiferromagnetic exchanges (J , m 270 cm-1) for the two complexes indicate a good overlap between the electronic orbitals of the square-planar copper(II) center via bridging oxygen atoms.