A new binucleating macrocyclic ligand 2,6-bis (1,4,7,10-te-traazacyclododecan-10-ylmethyl)methoxy-benzene (L) and its binuclear copper (II) complex, [ Cu2LBr2 ] (ClO4 )2 · 3H2O (1), was prepared and the structure was determined by X-ray crystallography. Complex 1 crystallizes in monoclinic crystal system, P21/n space group with a = 0.8206(3), b = 2.0892(8), c = 2.3053(7) nm, β=95.83(2)°, V = 3.932 nm3, Mr = 1017.57, Z = 4, Dc= 1.692 g/cm3, and R = 0. 0489, Rw= 0.0552 for 6571 observed reflections with I≥2σ (I). Both of the copper(II) centers are coordinated by four amine nitrogen donors of cyclen subunits and a bromide an-ion, and each copper (II) ion is in a square-pyramidal coordination environment. Variable temperature magnetic susceptibility studies indicate that there exists weak intramolecular an-tiferro-magnetic coupling ( - 2J = 2.06 cm-1) between the two copper(n) centers. A new binucleating macrocyclic ligand 2,6-bis (1,4,7,10-te-traazacyclododecan-10-ylmethyl) methoxy-benzene (L) and its binuclear copper (II) complex, [Cu2LBr2] (ClO4) 2 · 3H2O (1), was prepared and the structure was determined by X-ray crystallography. Complex 1 crystallizes in monoclinic crystal system, P21 / n space group with a = 0.8206 (3), b = 2.0892 (8), c = 748 nm, β = 95.83 (2) °, V = 3.932 nm3, Mr = 1017.57, Z = 4, Dc = 1.692 g / cm3 and R = 0.0489, Rw = 0.0552 for 6571 at reflections with I ≥ 2σ (I). Both of the copper (II) centers are coordinated by four amine nitrogen donors of cyclen subunits and a bromide an-ion, and each copper (II) ion is in a square-pyramidal coordination environment. Variable temperature magnetic susceptibility studies indicates that there exists weak intramolecular an-tiferro-magnetic coupling (-2J = 2.06 cm-1) between the two copper (n) centers.