Organometallic palladium and platinum complexes with strongly donating alkyl coligands: synthesis, structures, chemical and cytotoxic properties

The synthesis, spectroscopy, and structures of organometallic complexes [(COD)M(R)X] and [(COD)M(R)(R′)] (COD = 1,5-cyclooctadiene, M = Pd or Pt; R = methyl, neopentyl (2,2-dimethylpropyl), neosilyl (trimethylsilylmethyl), or benzyl; X = Cl, Br, or I; R′ = 2-phenyl-ethynyl, p-fluoro-2-phenyl- ethynyl, p-methyl-2-phenyl-ethynyl or p-nitro-2-phenyl-ethynyl) has been explored. Selected samples of organo-platinum complexes show strikingly high cytotoxicity when tested against HT-29 and MCF-7 tumour cells. Organo-palladium(II) and -platinum(II) complexes containing alkyl or alkynyl coligands and COD (1,5-cyclooctadiene) as chelating ligand were synthesised and thoroughly characterised by multinuclear NMR spectroscopy and XRD. Selected samples, namely the mixed alkyl alkynyl complexes, exhibit striking IC ₅₀ values when tested against HT-29 and MCF-7 tumour cells.