Chemistry at the apical position of square-pyramidal copper(II) complexes:: Synthesis, crystal structures, and magnetic properties of homopolynuclear complexes with azido bridges containing [Cu(AA)(BB)]+ moieties (AA = acetylacetonate;: BB=1,10-phenanthroline, bipy=2,2′-bipyridine)

Three new homopolynuclear complexes with azido bridges have been obtained by using [Cu(AA)(BB)](+) building-blocks (AA = acetylacetonate; BB = 1,10-phenanthroline or 2,2'-bipyridine). The reaction between [Cu(acac)(phen)(H2O)](ClO4) and NaN3 leads to a mixture of two compounds: it binuclear complex, [(Cu(acac)(phen)}2(mu(1,3)-N-3)](ClO4)center dot 2H(2)O (1), and a linear tetranuclear one, [{Cu(acae)(phen)(ClO4)}(2){Cu(phen)(mu(1,1)-N-3)(2)}(2)](2). The reaction between [Cu(acac)(bipy)(H2O)](ClO4) and NaN3 affords also a mixture of two compounds: [{Cu(acac)(bipy)}(2)(mu(1,3)-N-3)](3)(ClO4)(3)center dot 3.75H(2)O (3) and [Cu(acac)(bipy)(N-3)][Cu(acac)(bipy)(H2O)](ClO4) (4). The X-ray crystal structures of compounds 1-4 have been solved (for compound 4 the crystal structure was previously reported). In compounds 1 and 3, two {Cu(AA)(BB)} fragments are bridged by the azido anion in an end-to-end fashion. Two isomers, cis and trans with respect to azido bridge, were found in crystal 3. The structure of compound 2 consists of two Cu(II) central cations bridged by two mu(1,1)-azido ligands, each of them being also connected to a {Cu(acac)(phen)} fragment through another mu 1,1-azido ligand. The cryomagnetic properties of the compounds 1 and 2 have been investigated and discussed. The magnetic behaviour of compound 1 shows the absence of any interactions between the metallic ions. In the tetranuclear complex 2, the magnetic interactions between the external and central copper(II) ions (J(1)), and between the central metallic ions (J(2)) were found ferromagnetic (J(1) = 0.36 cm(-1), J(2) = 7.20 cm(-1)). (c) 2005 Elsevier B.V. All rights reserved.