Synthesis and structure of a dimeric hydroxo-bridged erbium(III) complex, di-μ-hydroxo-bis[(1,4,7,10,13,16-hexaazacyclooctadecane) erbium(III)] tetra(trifloromethanesulfonate)

The title complex was synthesized by the reaction of 1,4,7,10,13,16-hexaazacyclooctadecane (abbreviated as hexacyclen) with erbium(III) trifloromethanesulfonate in 1:1 (molar ratio) in acetonitrile under nitrogen. The crystal structure determination shows that the complex is dinuclear with two erbium ions bridged by two hydroxide ions. Each of the two metal ions is coordinated similarly by the two bridging hydroxide groups and six nitrogen atoms of a hexacyclen molecule, giving a coordination number eight and a slightly distorted dodecahedron geometry. The four trifloromethanesulfonate ions are not included in the coordination of the metal ions.