Synthesis, crystal structure and magnetic properties of the binuclear copper (II) complex of a new bis (1, 4, 7, 10‐tetraazacyclododecane) ligand

A new binucleating macrocyclic ligand 2,6‐bis (1,4,7,10‐tetraazacyclododecan‐10‐ylmethyl) methoxy‐benzene (L) and its binuclear copper (II) complex, [Cu 2 LBr 2 ] (CIO 4 ) 2 · 3H 2 O (1), was prepared and the structure was determined by X‐ray crystallography. Complex 1 crystallizes in monoclinic crystal system, P2 1 /n space group with a = 0.8206(3), b =2.0892(8), c = 2.3053(7) mn, β = 95.83(2)°, V = 3.932 nm 3 , Mr =1017.57, Z = 4, D c =1.692 g/cm 3 , and R = 0.0489, R w 0.0552 for 6571 observed reflections with I ≥ 2σ ( 1 ). Both of the copper(II) centers are coordinated by four amine nitrogen donors of cyclen subunits and a bromide anion, and each copper(II) ion is in a square‐pyramidal coordination environment. Variable temperature magnetic susceptibility studies indicate that there exists weak intramolecular antiferro‐magnetic coupling ( −2 J = 2.06 cm −1 ) between the two copper (II) centers.