The mononuclear precursors [Ni(trenpy)(OH2)](ClO4)(2) (1) and [Ni(dmptacn)(OH2)](ClO4)(2) (2) have been used to prepare the corresponding azide bridged binuclear Ni(II) complexes [Ni-2(trenpy)(2)(mu-N-3)](ClO4)(3) (3), where trenpy is N,N-bis(2-aminoethyl)-N’-(2-pyridylmethyl)ethane-1,2-diamine, and [Ni-2(dmptacn)(2)(mu-N-3)](ClO4)(3) (4), where dmptacn is 1,4-bis(2-pyridylmethyl)-1,4,7-triazacyc These complexes have been characterized using various physicochemical techniques. Single-crystal X-ray diffraction studies of [Ni-2(trenpy)2(mu-N-3)](ClO4)3 have shown that the compound crystallizes in the monoclinic space group, C2/c (No. 15), with a = 29.094(22) Angstrom, b 8.292(6) Angstrom, c = 15.127(12) Angstrom, beta = 92.93(6)degrees, and Z = 4. Least-squares refinement gave final R and R(W), values of 0.060 and 0.049, respectively, for 1401 observed reflections. The complex cation consists of two Ni-(II) centers in distorted octahedral environment held together by a single azide bridge. The binuclear unit is centrosymmetric with a Ni-N(azide) bond distance of 2.133(7) Angstrom, Ni-N-N angle of 131.6(5)degrees, and torsion angle of 0 degrees, The Ni-N(amine) bond lengths (2.07-2.11 Angstrom) are typical of Ni(II) amine complexes. The temperature dependence of the magnetic susceptibility for both complexes is typical of antiferromagnetically coupled binuclear Ni(II) complexes. Using the spin Hamiltonian, -2J (S) over cap(1).(S) over cap 2, J values of -26.8 and -42.5 cm(-1) were determined for 3 and 4, respectively.