Synthesis, characterization and magnetic properties of new homotrinuclear copper(II) complexes

摘要

Two new mononuclear bis(oxamato) complexes with the formula [nBU(4)N](2)[M(nabo)] M = Ni (4), Cu (5), with nabo = 2,3-naphthalene-bis(oxamato) have been synthesized as precursors for trinuclear oxamato-bridged transition metal complexes. Starting from 5 the homo-trinuclear complex [CU3(nabo)(pmdta)(2)(BF4)](BF4) center dot MeCN center dot Et2O (7), with pmdta =N,N,N',N", N" -pentamethyldiethylenetriamine, has been prepared. The central N,N'-2,3-naphthalene bridge of 7 is so far the most extended pi-conjugated bridge of trinuclear bis(oxamato) type transition metal complexes. The goal of this work was to verify the N,N'-2,3-naphthalene bridge of 7 on its magnetic properties in comparison to the N,N'-o-phenylene bridge of the related homo-trinuclear complex [CU3(opba)(pmdta)(2)(NO3)](NO3) 2 MeCN (6) (opba = o-phenylene-bis(oxamato)). The crystal structures of 4-7 were solved. The magnetic properties of 6 and 7 were studied by susceptibility measurements versus temperature. For the intramolecular J parameter, values of -89 cm(-1) (6) and -113 cm(-1) (7) were obtained. The different J values are discussed based on the crystal structures of 6 and 7. (c) 2007 Elsevier B.V. All rights reserved.