Platinum(II) complexes of 3,3'-disubstituted-2,2'-bipyridines. Synthesis, structures, cytotoxic effect and unusual solvolysis in DMSO

Abstract

The reaction of 3,3'-disubstituted-2,2'-bipyridines, 2,2'-bipyridyl-3,3'-dicarboxylic acid (H2BDC) and 3,3'-dimethylol-2,2'-bipyridine (DMB) with potassium tetrachloroplatinate(II) in water gives Pt(H2BDC)Cl-2 (1) and Pt(DMB)CI, (2), respectively. Both complexes were characterized by elemental analysis and various spectroscopic techniques. The molecular structures of 1 and 2 have been determined by single-crystal X-ray diffraction. 1.2DMF: triclinic system, space groupP1,alpha=8.089(9) Angstrom,b=9.707(8) Angstrom,c= 15.541(4) Angstrom,alpha = 106.88(6)degrees, beta=100.41(3)degrees: gamma=94.39(8)degrees, V=1137.8(2) Angstrom(3), Z=2. 2: monoclinic system, space group P2(1)/c, alpha=7.849(5) Angstrom, b=16.125(3) Angstrom, c=21.613(5) Angstrom, beta=94.10(2)degrees, V= 2728.5(9) Angstrom(3), Z=8. X-ray structures indicate that two pyridine rings of the bipyridyl ligand in both compounds cannot attain the coplanar state owing to the steric bulkiness of the substituents in the 3,3'-positions. The solvolysis of 1 in DMSO, characterized by H-1, C-13 and Pt-195 NMR spectra, leads to the unprecedented example for the complete release of the free amine ligand H2BDC, yielding the formation of cis-[Pt(Me2SO)(2)Cl-2]. No antitumor activity was observed for 1 and 2 against the leukemia L1210 cell line. (C) 1997 Elsevier Science S.A.