Cytotoxic activity of platinum (II) complexes with tri-n-butylphosphine. Crystal structure of the dinuclear hydrazine-bridged complex, cis,cis-[PtCl(PBu3n)2(mu-N2H4)PtCl(PBu3n) 2] (ClO4)2.2CHCl3.

A series of platinum(II) tri-n-butylphosphine complexes having the formulas cis-PtCl2L2], NEt4PtCl3L], PtCl(en)L]Cl, Pt(en)L2](ClO4)2, sym-trans-Pt2Cl4L2], Pt2Cl2L4](ClO4)2, trans,trans-PtCl2L(mu-N2H4)PtCl2L] trans,trans-PtCl2L(mu-en)PtCl2L], and cis,cis-PtClL2(mu-N2H4)PtClL2](ClO4)2 (L = tri-n-butylphosphine; en = ethylenediamine) have been synthesized and their cytotoxic activity in vitro and in vivo has been studied. The solution behavior of the novel dinuclear diamine-bridged platinum(II) complexes has been investigated by means of UV and 31P NMR spectroscopy. For the ionic hydrazine compound cis,cis-PtClL2(mu-N2H4)PtClL2](ClO4)2, an x-ray structure determination is reported. Crystal data: space group P2(1)/a, a = 17.803(1), b = 18.888(3), c = 12.506(3) A, beta = 107.97(2) degrees, Z = 2, R = 0.052, RW = 0.058. The platinum coordination is approximately square-planar, with the bond lengths Pt-Cl = 2.358(5), Pt-N = 2.15(1), Pt-P(trans to Cl) = 2.260(5), and Pt-P(trans to N) = 2.262(6) A. All investigated compounds were cytotoxic in vitro against L1210 cells and showed no cross-resistance to cisplatin. On the other hand, no antitumor activity was observed vs L1210 leucemia in DBA2 mice.