New complexes with the bridging ligand 4,4 -dipyrazolylmethane (dpzm) are reported. This ligand gives two types of complex with first transition series metals viz. [MCl 2 dpzm] n (M = Zn, Cu) and [MCl 2 dpzm 2 ] n (M = Mn, Fe, Co, Ni, Cu). X-ray powder diffraction shows the [MCl 2 dpzm 2 ] n series to be isostructural. DNA binding of [MCl 2 dpzm 2 ] n (M = Cu, Mn) and of [MCl 2 dpzm] n (M = Zn) has been studied and the anticancer properties of [MCl 2 dpzm] n (M = Zn, Cu) and [MCl 2 dpzm 2 ] n (M = Cu, Mn, Fe, Ni) investigated using an in vivo screen against P388 murine leukemia. The structure of CuCl 2 dpzm 2 2dmf (dmf = dimethylformide) has been determined from single crystal X-ray diffraction data as follows: monoclinic, space group P2 1 /c,a = 8.673(1), b = 17.572(2), c = 8.535(1) 9, β = 97.34(2)°, Z = 2. The structure consists of linear polymeric chains of CuCl 2 dpzm 2 molecules bridged through the N atoms of the ligand. The four equatorial N's give an average Cu-N distance of 2.017(2) 9 and the two axial chlorine atoms are at 2.799(1) 9 from the copper atom, giving an overall distorted octahedral structure. Following loss of the 2dmf of solvation the copper complex is isomorphous with the analogous first transition series complexes and a polymeric structure is considered likely.