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)

Abstract

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)(H 2O)](ClO 4) and NaN 3 leads to a mixture of two compounds: a binuclear complex, [{Cu(acac)(phen)} 2(μ 1,3-N 3)](ClO 4) · 2H 2O ( 1), and a linear tetranuclear one, [{Cu(acac)(phen)(ClO 4)} 2{Cu(phen)(μ 1,1-N 3) 2} 2] ( 2). The reaction between [Cu(acac)(bipy)(H 2O)](ClO 4) and NaN 3 affords also a mixture of two compounds: [{Cu(acac)(bipy)} 2(μ 1,3-N 3)] 3(ClO 4) 3 · 3.75H 2O ( 3) and [Cu(acac)(bipy)(N 3)][Cu(acac)(bipy)(H 2O)](ClO 4) ( 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 μ 1,1-azido ligands, each of them being also connected to a {Cu(acac)(phen)} fragment through another μ 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).