Crystal structures and cytotoxicity of isopropylamine Pt(II) complexes: a trinuclear squarato-bridged [Pt3(mu2-C4O4)3(H2NPri)6].3H2O and a mononuclear cis-[Pt(NO3)2(H2NPri)2].

Crystals of a novel platinum(II) complex with squarato ligand, [Pt(3)(mu(2)-C(4)O(4))(3)(H(2)NPr(i))(6)].3H(2)O (1) (H(2)NPr(i)=ipa), have been isolated from the aqueous solution of cis-[Pt(H(2)O)(2)(H(2)NPr(i))(2)]SO(4) and barium squarate. Slow evaporation of methanol solution of cis-[Pt(NO(3))(2)(H(2)NPr(i))(2)] (2) resulted in crystallization of nitrato complex. The single crystal X-ray diffraction method was used to determine structures of 1 and 2. Complex 1 crystallizes in a triclinic space group P1 with a=11.17380(10)A, b=14.4535(2)A, c=14.8010(2)A, alpha=86.0901(10) degrees , beta=78.4343(11) degrees , gamma=69.1915(5) degrees , and complex 2 in a monoclinic space group P2(1)/n, with a=10.1161(2)A, b=9.9188(2)A, c=13.3766(2)A, beta=102.7360(7) degrees . The X-ray structure analysis revealed that three platinum atoms in 1 are connected with three squarates which adopt bis(unidentate) binding modes. The squarato ligands span relatively long intramolecular Ptcdots, three dots, centeredPt distances (4.8842(3)-5.2699(3)A). A pair of cis positioned isopropylamine ligands completes a square planar coordination sphere of each Pt(II) ion. The square-planar coordination of complex 2 consists of two cis positioned isopropylamine ligands and two nitrato ligands. The results of cytotoxicity assay of trimer 1, monomer 2 and cis-diamminedichloroplatinum(II) (cisplatin) performed on human bladder tumor cell line T24 provide evidence that complex 2 is less cytotoxic compared to cisplatin and that the survival of tumor cells after exposure to 1 was minimally reduced.