A Macrocyclic Bistriazene and its Complexes with Divalent Metal Ions

The diazotisation of 2,2'-diaminotolane with one equivalent of HNO(2) yields the macrocyclic bis(tolanetriazene) (tolaneN(3)H)(2) in moderate yield. As shown by the crystal structure determination, the molecule is essentially planar. After deprotonation, the central cavity is suitable for complexation of transition metal ions. In pyridine solution, the anion (tolaneN(3))(2)(2-) is formed, which reacts with the acetates of Co(2+) and Ni(2+) to the dark red coloured complexes [M((tolaneN(3))(2))(py)(2)]. The metal ions are located in the centre of the macrocycles, coordinated by four N atoms of the two triazenide groups. Two pyridine ligands occupy the axial positions, giving the central atoms a distorted octahedral coordination environment. In the temperature range between 30 and 300 K, both complexes show the expected magnetic properties of magnetically isolated ions with nearly fulfilled Curie behaviour and mu(eff) = 3.40 for Ni(II) and 5.19 for Co(II), which is in the high spin state. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)