Dinuclear complexes of first transition series metals with 4,4′-dipyrazolylmethane:: characterisation, DNA binding and anticancer properties

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) Angstrom, beta = 97.34(2)degrees, 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) Angstrom and the two axial chlorine atoms are at 2.799(1) Angstrom 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. (C) 1998 Elsevier Science S.A.