Cu(bp3ca)Br-2 . H2O crystallizes in the triclinic space group P (1) over bar with a = 10.622(2) Angstrom, b = 10.832(2) Angstrom, c = 14.684(2) Angstrom, alpha = 106.13(1)degrees, beta = 105.91(1)degrees, gamma = 102.74(1)degrees, and Z = 2. The asymmetric unit consists of a bis mu-bromo unsymmetrically dibridged dimer which is further linked to its inversion-related partner to form a dimer of dimers. Weak intertetramer contacts are also observed. The magnetic data for this compound were fit to a linear tetramer model to give J(1) = J(3) = -8.69 x 10(-3) cm(-1), J(2) = 91.52 cm(-1), and the intertetramer interaction J' = -1.187 cm(-1) with g = 1.93. EPR data are consistent with the magnetic data. This system is compared to its previously reported chloro counterpart, which differs markedly in both structure and magnetic properties.