Macrocyclic nickel(II) complexes with a folded conformation. Synthesis, properties and structures of [NiL(en)][Ni(en)(3)] (ClO4)(4) and [(NiL)(2)(mu-ox)](ClO4)(2) (L=3,10-bis(2-hydroxyethyl)1,3,5,8,10,12-hexaazacyclotetradecane, en = ethylenediamine,

摘要

Two nickel(II) complexes with the formula [NiL(en)][Ni(en)(3)](ClO4)(4) (1) and [(NiL)(2)(mu -ox)](ClO4)(2) (2), where L = 3.10-bis(2-hydroxyethyl)-1,3,5,8,10,1 2-hexaazacyclotetradecane, en = ethylenediamine, ox = oxalate anion, have been synthesized and characterized by elemental analyses, IR and electronic spectra and single-crystal X-ray analyses. The structure of 1 is made up of [NiL(en)](2+) and [Ni(en)(3)](2+) cations and four uncoordinated ClO4- anions. The structure of 2 consists of two uncoordinated ClO4- anions and one centrosymmetrical mu -oxalata-bridged binuclear nickle(II) cation [(NiL)(2)(mu -ox)](2+), in which the oxalate ion acts as a bis-bidentate ligand between two nickel (II) ions. In both complexes, the macrocycle adopts a folded conformation around the nickle atoms, which are six-coordinated in octahedral distorted arrangements. Magnetic susceptibility measurements of 2 in the temperature range 5.1-300 K show that the two nickel(II) ions of the binuclear unit are coupled antiferromagnetically with J = -13.8 cm(-1) and g = 2.02, T-N being ca. 40 K. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 22]