Synthesis, structures and magnetic properties of pentanuclear and trinuclear heterometallic complexes with bended and linear cyano-bridges (tren = tris(2-aminoethyl)amine)

The reaction of [Cu(tren)(OH2)](ClO4)(2) with KCN gave a mononuclear complex [Cu(tren)(CN)](ClO4) (1) (tren = tris(2-aminoethyl)amine). Using 1 as a building block, one pentanuclear compound, [{Cu(tren)(NC)}(4)Ni](ClO4)(6) (2) and two trinuclear complexes, [{Cu(tren)NC}(2)Co(tren)](ClO4)(5)(.)2H(2)O (3), ((Cu(tren)CN)(2)NiL](CIO4)4 (4) (L=3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane) were prepared and characterized by single crystal X-ray analysis. In 1, Cu(II) atom adopts a distorted trigonal bipyramidal (TBP) geometry. In 2, the Ni(II) atom occupies the center of the pentanuclear compound with a square-planar coordination geometry. III 3, the six-coordinated Co(III) atom presents a distorted octahedral geometry with four nitrogen atoms from tren and two carbon atoms of bridged cyano groups in cis-positions. In 4, the nickel atom is located in an inversion center and coordinated with two [(tren)CuCN](+) moieties through cyano-bridging ligands. Magnetic susceptibility measurements of 2-4 show that the magnetic interactions between the heterometallic ions are antiferromagnetical coupling through the cyano bridges with g = 2.25, J = -0.142 cm(-1) and J' = -0.167 cm(-1) for 2, g = 2.06, J = -0.094 cm(-1) for 3, and g = 2.20, J = -33.133 cm(-1) for 4. The correlations between the structures and the J values are discussed. (c) 2006 Elsevier B.V. All rights reserved.