The copper complexes with the commercial aw;in herbicides MCPA, 2,4-D, and 2,4,5-T in the presence of a nitrogen donor heterocyclic ligand, phen or bipyam, were prepared and characterized. The available evidence supports a dimeric structure for the 2,4-D complex in the presence of bipyam while phen leads to monomeric forms. The EPR spectrum of Cu-2(2,4-D)4(bipyam)(2) at 4 K in the solid state exhibits an axial signal which corresponds to almost isolated S = 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = -0.8 cm(-1). The crystal structures of tetrakis[(2,3-dichlorophenoxy)-acetato]bis(2,2'-bipyridylamine)dicopper(II), 1, bis(1,10-phenanthroline) [(2,4,5-trichlorophenoxy) acetato] copper (II) chloride, 2, and aqua(1,10-phenanthroline)bis[((2-methyl-4-chlorophenoxyacetato]copper(II), 3, were determined and refined by least-squares methods using three-dimensional MoK alpha data. 1 crystallizes in space group P (1) over bar, in a cell of dimensions a = 10.813(1) Angstrom, b = 12.138(1) Angstrom, c = 11.909(1) Angstrom, alpha = 86.448(3)degrees, beta = 80.127(3)degrees and gamma = 63.982(3)degrees, and V = 1383.7(2) Angstrom(3), with Z = 1. 2 crystallizes in space group I2/a, in a cell of dimensions a = 29.958(9) Angstrom, b = 11.342(3) Angstrom, c = 21.196(7) Angstrom, beta = 107.94(1)degrees, and V = 6852.2(4) Angstrom(3), with Z = 8. 3 crystallizes in space group P (1) over bar, in a cell of dimensions a = 8.7419(8) Angstrom, b = 12.512(1) Angstrom, c = 14.598(1) Angstrom, alpha = 110.737(1)degrees, beta = 95.742(2)degrees, gamma = 103.286(2)degrees, V = 1424.1(2) Angstrom(3), with Z = 2.