- Heteroditopic P,N ligands in gold(I) complexes: Synthesis, structure and cytotoxicity
-
New heteroditopic, bi- and multidentate imino- and aminophosphine ligands were synthesised and complexed to [AuCl(THT)] (THT = tetrahydrothiophene). X-ray crystallography confirmed Schiff base formation in three products, the successful reduction of the imino-group to the sp3-hybridised amine in several instances, and confirmed the formation of mono-gold(I) imino- and aminophosphine complexes for four Au-complexes. Cytotoxicity studies in cancerous and non-cancerous cell lines showed a marked increase in cytotoxicity upon ligand complexation to gold(I). These findings were supported by results from the 60-cell line fingerprint screen of the Developmental Therapeutics Programme of the National Institutes of Health for two promising compounds. The cytotoxicity of some of these ligands and gold(I)complexes is due to the induction of apoptosis. The ligands and gold(I)complexes demonstrated selective toxicity towards specific cell lines, with Jurkat T cells being more sensitive to the cytotoxic effects of these compounds, while the non-cancerous human cell line KMST6 proved more resistant when compared to the cancerous cell lines. Results from the NIH DTP 60 cell-line fingerprint screen support the observed enhancement of cytotoxicity upon gold(I) complexation. One gold(I)complex induced high levels of apoptosis at concentrations of 50 μM in all the cell lines screened in this study, while some of the other compounds selectively induced apoptosis in the cell lines. These results point towards the potential for selective toxicity to cancerous cells through the induction of apoptosis.
- Traut-Johnstone, Telisha,Kanyanda, Stonard,Kriel, Frederik H.,Viljoen, Tanya,Kotze, P.D. Riekert,Van Zyl, Werner E.,Coates, Judy,Rees, D. Jasper G.,Meyer, Mervin,Hewer, Raymond,Williams, D. Bradley G.
-
-
Read Online
- Imine-Centered Reactions in Imino-Phosphine Complexes of Iron Carbonyls
-
Fundamental reactions of imino-phosphine ligands were elucidated through studies on Ph2PC6H4CH=NC6H4-4-Cl (PCHNArCl) complexes of iron(0), iron(I), and iron(II). The reaction of PCHNArCl with Fe(bda)(CO)3 gives Fe(PCHNArCl)(CO)3 (1), featuring an η2-imine. DNMR studies, its optical properties, and DFT calculations suggest that 1 racemizes on the NMR time scale via an achiral N-bonded imine intermediate. The N-imine isomer is more stable in Fe(PCHNArOMe)(CO)3 (1OMe), which crystallized despite being the minor isomer in solution. Protonation of 1 by HBF4·Et2O gave the iminium complex [1H]BF4. The related diphosphine complex Fe(PCHNArCl)(PMe3)(CO)2 (2), which features an η2-imine, was shown to also undergo N protonation. Oxidation of 1 and 2 with FcBF4 gave the Fe(I) compounds [1]BF4 and [2]BF4. The oxidation-induced change in hapticity of the imine from η2 in [1]0 to κ1 in [1]+ was verified crystallographically. Substitution of a CO ligand in 1 with PCHNArCl gave Fe[P2(NArCl)2](CO)2 (3), which contains the tetradentate diamidodiphosphine ligand. This C-C coupling is reversed by chemical oxidation of 3 with FcOTf. The oxidized product of [Fe(PCHNArCl)2(CO)2]2+ ([4]2+) was prepared independently by the reaction of [1]+, PCHNArCl, and Fc+. The C-C scission is proposed to proceed concomitantly with the reduction of Fe(II) via an intermediate related to [2]+.
- Chu, Wan-Yi,Richers, Casseday P.,Kahle, Elizabeth R.,Rauchfuss, Thomas B.,Arrigoni, Federica,Zampella, Giuseppe
-
-
Read Online
- Influence of various P/N and P/P ligands on the palladium-catalysed reductive carbonylation of nitrobenzene
-
A series of bidentate phosphorus-nitrogen ligands was synthesised for the palladium-catalysed reductive carbonylation of nitrobenzene in order to combine the favourable influence of the phosphorus atom on the stability of the catalyst complex with the stimulating effect of the nitrogen atom on the catalytic activity. The nitrogen atom of the P/N ligand was either incorporated in an imine function, yielding the JV-(2′-diphenylphosphinobenzylidene)-R-amine ligands (R = phenyl, 4-chlorophenyl, 2,4-dimethoxyphenyl, 2,4-dimethylphenyl, tert-butyl), or in a heteroaromatic ring system which gave 2-(2′-(diphenylphosphino)ethyl)pyridine and 8-(diphenylphosphino)quinoline. Complexes of the type Pd(ligand)2(BF4)2 were prepared for these ligands. Additionally, a series of bidentate phosphorus ligands was tested: dppm, dppe, dppp, dppb, dppf, 1,2-bis(diphenylphosphino)benzene, 1,8-bis(diphenylphosphino)naphthalene, bis(2-diphenylphosphinophenyl)ether, and 9,9-dimethyl-4,6-bis(diphenylphosphino)xanthene. The P/N ligands containing the imine function did not yield any conversion of the nitrobenzene in combination with Pd. On the use of the second type of P/N ligand, moderately active palladium catalysts were obtained. This different behaviour is ascribed to the relatively low π *-level of the imine-containing ligands. Oxidation of the phosphorus donor atom by the nitro substrate inactivated the catalysts derived from the P/N ligands as well as from a series of P/P ligands. For the bidentate phosphorus ligands the bite angle and flexibility of the ligand turned out to be of crucial influence due to the different geometries required for the Pd(II) and Pd(0) intermediates of the catalytic cycle.
- Wehman, Petra,Van Donge, Hans M.A.,Hagos, Alay,Kamer, Paul C.J.,Van Leeuwen, Piet W.N.M.
-
-
Read Online
- Arene-ruthenium(II) complexes containing amino-phosphine ligands as catalysts for nitrile hydration reactions
-
Three different series of novel mononuclear arene-ruthenium(II) complexes containing amino-phosphine ligands, namely, [RuCl2{κ 1(P)-2-Ph2PC6H4CH 2NHR}(η6-arene)], [RuCl2{κ 1(P)-3-Ph2PC6H4CH 2NHR}(η6-arene)], and [RuCl2{κ 1(P)-4-Ph2PC6H4CH 2NHR}(η6-arene)] (arene = C6H6, p-cymene, 1,3,5-C6H3Me3, C6Me 6; R = iPr, tBu; all combinations), have been synthesized and fully characterized. These readily accessible species are efficient catalysts for the selective hydration of organonitriles into amides under challenging reaction conditions, i.e., pure aqueous medium in the absence of any cocatalyst, being much more active than their corresponding nonfunctionalized triphenylphosphine counterparts [RuCl2(PPh 3)(η6-arene)]. The results obtained in this study indicate that the (amino-phosphine)ruthenium(II) complexes operate through a "bifunctional catalysis" mechanism in which the ruthenium center acts as a Lewis acid, activating the nitrile molecule, and the P-donor ligand acts as a Brnsted base, the pendant amino group generating the real nucleophile of the hydration process, i.e., the OH- group.
- Garcia-Alvarez, Rocio,Diez, Josefina,Crochet, Pascale,Cadierno, Victorio
-
scheme or table
p. 3955 - 3965
(2010/12/25)
-
- Rhodium Iminophosphine Complexes as Efficacious Oxygen Carriers. Crystal Structure of a Representative Dioxygen Adduct
-
The synthesis, characterization and reactivity of some square-planar rhodium(I) complexes with new bidentate ligands o-Ph2PC6H4CH=NR (R = Et, Prn, Pri or But) having NP donor atoms have been investigated.Depending on the steric crowding of the ligands the complexes can reversibly form dioxygen adducts, in organic solvent solutions at room temperature.The oxygenation-deoxygenation cycles, which have been monitored by 31P NMR spectroscopy, can be repeated several times with minor loss in the starting material.A reversible adduct is similarly obtained by reaction with CO.The reaction of the dioxygen adduct with SO2 allows the formation of a sulfate derivative.The molecular structure of the dioxygen complex i)2(O2)>BPh4 has been determined by a single-crystal diffraction study: triclinic, space group P, a = 17.450(7), b = 16.518(7), c = 9.624(5) Angstroem, α = 92.79(6), β = 92.52(7), γ = 92.69(7) deg, Z = 2, R = 0.057.The co-ordination of the metal may be alternatively described as distorted trigonal bipyrimidal or distorted octahedral, according to whether the dioxygen molecule is treated as occupying one or two equatorial sites respectively.The two oxgen atoms, which are equidistant from the metal, are 1.436(9) Angstroem apart.
- Ghilardi, Carlo A.,Midollini, Stefano,Moneti, Simonetta,Orlandini, Annabella,Scapacci, Giancarlo
-
p. 3371 - 3376
(2007/10/02)
-