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The 1 : 2 adducts of copper(i) halides with 1,2-bis(2-pyridylphosphino)ethane (d2pype) have been synthesized and solution properties characterized by variable temperature 1H, 31P and 65Cu NMR spectroscopy. Single-crystal structure determinations for the chloride, bromide and iodide complexes show these to crystallize from acetonitrile in the triclinic space group P1 as isostructural centrosymmetric dimers [(d2pype)Cu(μ-d2pype)2Cu(d2pype)]X2·(solvent) with a∼ 12.6, b∼ 12.7, c∼15.3 , α∼ 84, β∼ 67, γ∼ 84°. In contrast to the analogous AuCl:2(d2pype) and AgNO3:2(d2pype) adducts, in solution these CuX:2(d2pype) adducts (where X = Cl, Br and I) exist almost exclusively as bis-chelated monomeric [Cu(d2pype)2]X; evidence for an equilibrium between monomeric and dimeric forms is detected only for the CuCl adduct in methanol. Cytotoxicity studies in two human breast cancer lines and two matched liver progenitor cell lines indicate that [Cu(d2pype)2]Cl is non selectively toxic to both non-tumourigenic and tumourigenic cells. However, the analogous Au(i) compound [Au(d2pype)2]Cl, is toxic to highly tumourigenic cells and more selective in its toxicity to tumourigenic cells compared to non-tumourigenic cells. The significance of these results to the further development of selective, mitochondria-targeted, Au(i) antitumour complexes is discussed. [ABSTRACT FROM AUTHOR]

The novel water soluble bidentate phosphine ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp) has been synthesized by a convenient route involving treatment of 2-pyridyllithium with Cl2P(CH2)3PCl2 and isolation in crystalline form as the hydrochloride salt. The synthesis of the precursor Cl2P(CH2)3PCl2 has been optimized by the use of triphosgene as the chlorinating agent. The 2 : 1 and 1 : 2 AuCl : d2pypp adducts have been synthesized and characterized by NMR spectroscopy and single crystal X-ray studies, and shown to be of the form (AuCl)2(µ-d2pypp-P,P′) and [Au(d2pypp-P,P′)2]Cl(·3.75H2O), respectively. The latter is more lipophilic than analogous 1 : 2 adducts of gold(i) chloride with the diphosphine ligands 1,2-bis(di-n-pyridylphosphino)ethane (dnpype) for n = 2, 3 and 4, based on measurement of the n-octanol–water partition coefficient (log P = −0.46). A single crystal structure determination of the 1 : 2 Au(i) complex of the 3-pyridyl ethane ligand shows it to be of the form [Au(d3pype-P,P′)2]Cl·5H2O. The in vitro cytotoxic activity of [Au(d2pypp)2]Cl was assessed in human normal and cancer breast cells and selective toxicity to the cancer cells found. The significance of these results to the antitumour properties of chelated 1 : 2 Au(i) diphosphine complexes is discussed. [ABSTRACT FROM AUTHOR]