Binuclear copper(II) complexes of composition [Cu-2(OH/OMe)(O(2)CPh)(2)(tmen)(2)](PF6) (1) are prepared by reacting copper(II) benzoate with N,N,N’,N’-tetramethylethane-1,2-diamine (tmen) in methanol followed by an addition of NH4PF6. The crystalline product 1 is a 1:1 mixture of two complexes viz. [Cu-2(OH)(O(2)CPh)(2)(tmen)(2)](PF6) (1a) and [Cu-2(OMe)(O(2)CPh)(2)(tmen)(2)](PF6) (1b) but the homogeneous crystalline mass 2, obtained from a similar reaction in ethanol, has a composition of 1a . 1a . H2O . 0.5NH(4)PF(6), i.e, two la molecules in the crystallographic; asymmetric unit. The formulation of the products 1 and 2 has been made from the X-ray structural studies and analytical data. Crystal data are as follows : 1, orthorhombic, P2(1)2(1)2(1), a = 12.364(3) Angstrom, b = 19.560(4) Angstrom, c 29.071(3) Angstrom, alpha = beta = gamma = 90 degrees, Z = 4; 2, rhombohedral, , a = b = 27.083(10), c = 56.096(9) Angstrom, alpha = beta = 90 degrees, gamma = 120 degrees, Z = 18. The complexes have a [Cu-2(mu-OH/OMe)(mu-O(2)CPh)(2)(tmen)(2)](+) core with bidentate chelating tmen as terminal ligands. The geometry at the copper ion is essentially square-pyramidal with one carboxylate bridge occupying the apical sites giving much longer Cu-O bond distances compared to those at the basal planes. The Cu Cu distances and Cu-O-Cu angles in the core lie in the range 3.229(1)-3.259(3) Angstrom and 112.6(2)-115.7(8)degrees. The dihedral angles between two copper planes are 38.31, and 44.20 degrees for 1 and 39.70 and 41.68 degrees for 2. The complexes display axial X-band EPR spectral features in the polycrystalline state at 77 K giving g(11) = 2.28 (A(11) = 150 x 10(-4) cm(-1)), g(perpendicular to) = 2.08 for 1 (1a . 1b . H2O) and g(11) = 2.25 (A(11) = 150 x 10(-4) cm(-1)), g(perpendicular to) = 2.07 for 2 (1a . 1a . H2O . 0.5NH(4)PF(6)). In addition, both the complexes display a Delta M(s) = 2 transition at g = 4.42 indicating the presence of spin-exchange coupling. The complexes are ferromagnetic and the theoretical fit of the susceptibility data in the temperature range 300-20 K gives 2J = 35.4 cm(-1), Theta = 8.4 K, g = 2.0 for 1 and 2J = 45.1 cm(-1), Theta = 9.7 K, g = 2.0 for 2. The sum of the angles at oxygen of OH and OMe in 1a . 1b . H2O is 333 degrees (average). The ferromagnetism of 1 has been found to be related to the pyramidal geometry at oxygen. The magnetostructural properties of this emerging class of tribridged dicopper(II) complexes presenting a new spin system have been discussed.