First bivalent palladium and platinum cyanoximates: synthesis, characterization, and biological activity

A series of five cyanoximes (compounds having the general formula NC-C(=NOH)-R, where R is an amide or carboxylic ester group) have been synthesized and spectroscopically and structurally characterized. These are 2-cyano-2-isonitrosoacetamide (later HACO), 2-cyano-2-isonitrosothioacetamide (HTCO), 2-cyano-2-isonitrosoethylacetate (HECO), 2-cyano-2-isonitroso-N-piperidinylacetamide (HPiPCO), and 2-cyano-2-isonitroso-N-morpholinylacetamide (HMCO). A high yield method of synthesis was developed for the last two previously unknown amidocyanoximes. Variable temperature (13)C NMR studies in DMSO-d(6) solutions allowed the determination of rotational energy barriers for these two new cyanoximes. The HPiPCO and HMCO oxime molecules adopt a trans-anti configuration in the solid state according to X-ray analysis. Reactions between aqueous solutions of K(+)L(-) (L = cyanoximate anions: TCO(-), PiPCO(-), and MCO(-)) and K(2)[MCl(4)] (M = Pd, Pt) resulted in the formation of ML(2) complexes. The crystal structure of Pd(MCO)(2).DMSO was determined and showed the formation of coplanar dimeric [Pd(MCO)](2) units with 3.13 A Pd...Pd separation. The complex adopts cis geometry with anions being in the nitroso form. In the presence of bivalent Pd and Pt, ACO(-) and ECO(-) anions completely or partially hydrolyze in aqueous solutions to the dianion of 2-cyano-2-isonitrosoacetic acid (AACO(2-)). The crystal structure of the product of the hydrolysis reaction, K(2)[Pd(AACO)(2)].4H(2)O, was determined. Data revealed planar and cis geometry of the [Pd(AACO)(2)](2)(-) anion where cyanoximes are in the nitroso form and adopt a cis-anti configuration. All synthesized cyanoxime ligands and nine of their Pd(II) and Pt(II) complexes were tested in vitro on antiproliferating activity using human cervical cancer HeLa cell lines, and cisplatin as a positive control substance. Two out of the nine studied complexes, Pd(MCO)(2) and Pt(MCO), were found to be active compounds inflicting death on 28% and 16% of the cells, respectively, with 55% value for the cisplatin under the same conditions.     

Synthesis and characterization of platinum and palladium pyrrolidinedithiocarbamate complexes

Treatment of (PPh₃)₂MCl₂ (M = Pd or Pt) with ammonium pyrrolidinedithiocarbamate (NH₄S₂CNC₄H₈) in a 1:1 molar ratio gave (PPh₃)M(Cl)(κ ² S,S-S₂CNC₄H₈) [M = Pt (1), Pd (2)]. On the other hand, the interaction of these compounds in a 1:2 [M:L] molar ratio gave (PPh₃)Pt(κS-S₂CNC₄H₈)(κ ² S,S-S₂CNC₄H₈) (3), which contains both terminal and chelated dithiocarbamato ligands, or a yellow insoluble solid for M = Pd. The bis(diphenylphosphino)ethane platinum or palladium dichlorides [(dppe)MCl₂] reacted with the same ligand to give the salts [(dppe)M(κ ² S,S-S₂CNC₄H₈)]Cl (M = Pt (4), Pd (5) which have only one chelating dithiocarbamato ligand. The new compounds were characterized by ¹H-, ¹³C{¹H}- and ³¹P-n.m.r. spectroscopy, mass spectrometry, elemental analysis and X-ray single crystal structure analysis.     

First palladium(II) and platinum(II) complexes from employment of 2,6-diacetylpyridine dioxime: synthesis, structural and spectroscopic characterization, and biological evaluation

Employment of the monoanion of 2,6-diacetylpyridine dioxime (dapdoH(2)) as a tridentate chelate in palladium(II) and platinum(II) chemistry is reported. The syntheses, crystal structures, spectroscopic and physicochemical characterization, and biological evaluation are described of [PdCl(dapdoH)] (1) and [PtCl(dapdoH)] (2). Reaction of PdCl(2) with 2 equivs of dapdoH(2) in MeOH under reflux gave 1, whereas the same reaction with PtCl(2) in place of PdCl(2) gave 2 in comparable yields (70-80%). The divalent metal center in both compounds is coordinated by a terminal chloro group and a N,N',N"-tridentate chelating (η(3)) dapdoH(-) ligand. Thus, each metal ion is four coordinate with a distorted square planar geometry. Characterization of both complexes with (1)H and (13)C NMR and UV-vis and electrospray ionization mass spectroscopies confirmed their integrity in DMSO solutions. Interaction of the complexes with human and bovine serum albumin has been studied with fluorescence spectroscopy, revealing their affinity for these proteins with relatively high values of binding constants. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that they can bind to CT DNA, and the corresponding DNA binding constants have been evaluated. Cyclic voltammograms of the complexes in the presence of CT DNA solution have shown that the interaction of the complexes with CT DNA is mainly through intercalation, which has been also shown by DNA solution viscosity measurements. Competitive studies with ethidium bromide (EB) have revealed the ability of the complexes to displace the DNA-bound EB, suggesting competition with EB. The combined work demonstrates the ability of pyridyl-dioxime chelates not only to lead to polynuclear 3d-metal complexes with impressive structural motifs and interesting magnetic properties but also to yield new, mononuclear 4d- and 5d-metal complexes with biological implications.     

Halo-carbonyl complexes of palladium,platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided.     

Paramagnetic complexes of platinum and palladium with acetamide

Summary Direct reaction of K₂MCl₄ (M=Pt or Pd) with acetamide leads reproducibly to complexes which can be formulated as [Pt(C₂H₄ON)₂Cl]_n and Pd₄(C₂H₄ON)₇(OH)₂. Analytical and spectroscopic (i.r., n.m.r. and e.p.r.) data support the existence of polynuclear structures involving bridging ligands and partially oxidized metal centres.     

Synthesis, characterization and biological evaluation of platinum(II) complexes with a chiral N-monosubstituted 1,2-cyclohexyldiamine derivative

Eight platinum(II) compounds with a new chiral ligand, 2-(((1R,2R)-2-aminocyclohexylamino)methyl)phenol (HL), were designed, prepared and spectrally characterized. All compounds showed better aqueous solubility than cisplatin and oxaliplatin. In vitro cytotoxicity of these compounds against human HepG-2, MCF-7, A549 and HCT-116 cell lines was evaluated. Results indicated that all compounds showed cytotoxicity against A549 and HepG-2 cell lines. Particularly, compounds B1 and B8, which have CF?SO?? and (CH?)?COCH?COO(-) as leaving groups, respectively, exhibited better cytotoxicitiy than that of carboplatin in these two cell lines.     

Xylyl isocyanide platinum and palladium complexes

Bis(cycloocta-1,5-diene)platinum reacts with isopropyl isocyanide to give the trinuclear complex [Pt₃(CNPrⁱ)₆]. A related palladium compound was prepared by treating either [Pd(dba)₂] or [Pd₂(dba)₂CHCl₃] with 2,6-dimethylphenyl isocyanide. Reactions of the cluster [Pt₃(CNC₆H₃-2,6-Me₂)₆] and its presumed palladium analogue with the olefins (NC)₂C:C(CN)₂, F₂C:CFCl and (CN)₂C:C(CF₃)₂, give the compounds [M(olefin)(CNC₆H₃-2,6-Me₂)₂] (M  Pt, Pd) in which the metals are η²-bonded to the coordinated olefins. The compound [Pd₃(CNC₆H₃-2,6-Me₂)₆] reacts with F₂C:CFBr and with F₂C:CFCl to give the trans complexes [Pd(X)(C₂F₃)(CNC₆H₃-2,6-Me₂)₂] (X  Br, Cl). Similar compounds [M(L)-(CNC₆H₃-2,6-Me₂)₂] (M  Pt, Pd), (L  MeO₂CHC:CHCO₂Me, OOCH: CHCOO) have also been prepared, and characterised. Two platinum complexes [Pt(CH:NC₆H₃-2,6-Me₂)(SiMePh₂)(CNC₆H₃-2,6-Me₂)₂] and [Pt₂(μ-(PhC)₂CO)(CNC₆H₃-2,6-Me₂) ₄] hav been synthesized by treating the complex [Pt₃(CNC₆H₃-2,6-Me₂)₆] with HSiMePh₂ and cyclopropenone, respectively. NMR and IR data for the new species are reported and discussed.     

Extraction chromatography of palladium and platinum complexes with nitroso-R-salt

The retention of palladium and platinum complexes with nitroso-R-salt on silica gel treated with Aliquat 336 has been investigated. The complexation of platinum with nitroso-R-salt (NRS) requires heating of H₂PtCl₆ with an excess of NRS at 100°. The affinity of the complexes for an Aliquat 336 stationary phase increases in the following order: PdCl₄²⁻ ˜ Pt-NRS < PtCl₆²⁻ Pd-NRS. The complexes of palladium and platinum can be separated by column chromatography on silica treated with Aliquat 336 and eluted with 0.25M perchloric acid (Pt) and 1M perchloric acid (Pd).     

Pincer-like amido complexes of platinum, palladium, and nickel

The ligands bis(8-quinolinyl)amine (BQAH, 1), (2-pyridin-2-yl-ethyl)-(8-quinolinyl)amine (2-pyridin-2-yl-ethyl-QAH, 2), o-dimethylaminophenyl(8-quinolinyl)amine (o-(NMe2)Ph-QAH, 3), and 3,5-dimethylphenyl(8-quinolinyl)amine (3,5-Me2Ph-QAH, 4) have been prepared in high yield from aryl halide and amine precursors by palladium-catalyzed coupling reactions. Deprotonation of 1 with nBuLi in toluene affords the lithium amide complex [Li][BQA] (5), whose dimeric solid-state crystal structure is presented. Lithium amide 5 was transmetalated by TlOTf to afford the thallium(I) amido complex [Tl][BQA] (6). An X-ray structural study of 6 shows it to be a 1:1 complex of the BQA ligand and Tl. Entry into the group 10 chemistry of the parent ligand 1 was effected by both protolytic and metathetical strategies. Thus, the divalent chloride complexes (BQA)PtCl (7), (BQA)PdCl (8), and (BQA)NiCl (9) were prepared and fully characterized. An X-ray structural study for each of these three complexes shows them to be well-defined, square-planar complexes in which the auxiliary BQA ligand binds in a planar, eta(3)-fashion. For comparison, the reactivity of ligands 2-4 with (COD)PtCl2 was studied. While reaction with ligand 2 afforded an ill-defined product mixture, ligands 3 and 4 reacted with (COD)PtCl2 to generate the unusual alkyl complexes (o-(NMe2)Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (10) and (3,5-Me2Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (11), both of which have been structurally characterized.     

Pyrazole-3-carboxylates assisted N-heterocyclic carbene palladium complexes: synthesis,characterization, and catalytic activities towards arylation of azoles with arylsulfonyl hydrazides

Four mononuclear and dinuclear pyrazole-3-carboxylates assisted NHC–Pd complexes have been synthesized and characterized. Notably, the bridge-cleavage reactions of [Pd(μ-Cl)(Cl)(NHC)]₂ with 1H-pyrazole-3-carboxylic acid afforded dinuclear complexes [(NHC)Pd(μ-1H-pyrazolato-3-carboxylate)]₂, in which the 1H-pyrazolato-3-carboxylate was employed as a N^N^O dianionic chelating and bridging ligand. To further explore the structural features and catalytic properties of the complexes, 1-methyl-1H-pyrazole-3-carboxylic acid was introduced into the coordination with [Pd(μ-Cl)(Cl)(NHC)]₂ and the corresponding mononuclear complexes (NHC)PdCl(1-methyl-1H-pyrazole-3-carboxylate) were obtained. The catalytic properties of the complexes in desulfitative arylation of azoles with arylsulfonyl hydrazides were initially investigated.     

Coordination polymers of glutaraldehyde with glycine metal complexes: synthesis,spectral characterization,and their biological evaluation

Glycine metal complexes were prepared by the reaction of glycine with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) in 1?:?2 molar ratio. Thereafter their condensation polymerization was done with glutaraldehyde to obtain polymer metal complexes. All the synthesized polymer metal complexes were characterized by elemental analysis, FT-IR, ¹H-NMR, and UV-Vis spectrometry, magnetic susceptibility, and thermogravimetric studies. The analytical data of all the polymers agreed with 1?:?1 molar ratio of metal complex to glutaraldehyde and magnetic moment data suggest that PGG–Mn(II), PGG–Co(II), PGG–Ni(II), and PGG–Cu(II) have an octahedral geometry around the metal atom, whereas the tetrahedral geometry was proposed for PGG–Zn(II) polymer. The PGG–Mn(II) and PGG–Cu(II) showed octahedral geometry. Thermal behavior of the polymer metal complexes was obtained at a heating rate of 10°C?min^?1 under nitrogen atmosphere from 0°C to 800°C. The antimicrobial activities of synthesized polymers were investigated against Streptococcus aureus, Escherichia coli, Bacillus sphaericus, Salmonella sp. (Bacteria), Fusarium oryzae, Candida albicans, and Aspergillus niger (Yeast).     

Nitrate complexes of divalent palladium and platinum

Conclusions Some nitrate complexes of Pd(II) and Pt(II) were synthesized. The absorption bands of the nitrate groups in the IR spectra of the obtained complexes were studied in the 900–1700 cm^–1 region. A study was also made of the NMR spectra of the nitrate complexes of Pt(II) in D₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1677–1679, July, 1977.     

Triphenylphosphine carboxylate complexes of platinum and palladium

Conclusions Some carboxylate complexes of platinum and palladium of type (Ph₃P)₂M(OOCR)₂ were obtained by the reaction of organic acids with the complexes (Ph₃P)₄Pt and (Ph₃P)₄Pd.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 946–947, April, 1973.     

Dinuclear ruthenium and iron complexes containing palladium and platinum with tri-tert-butylphosphine ligands: synthesis, structures, and bonding

The reaction of Pd(PBu(t)(3))(2) with Ru(CO)(5) yielded the dipalladium-diruthenium cluster complex Ru(2)(CO)(9)[Pd(PBu(t)(3))](2), 10. The reaction of Pt(PBu(t)(3))(2) with Ru(CO)(5) at room temperature afforded the diplatinum-diruthenium cluster complex Ru(2)(CO)(9)[Pt(PBu(t)(3))](2), 12, and the monoplatinum-diruthenium cluster PtRu(2)(CO)(9)(PBu(t)(3)), 11. All three complexes contain a diruthenium group with bridging Pd(PBu(t)(3)) or Pt(PBu(t)(3)) groups. Compound 11 can be converted to 12 by reaction with an additional quantity of Pt(PBu(t)(3))(2). The reaction of 12 with hydrogen at 68 degrees C yielded the dihydrido complex Pt(2)Ru(2)(CO)(8)(PBu(t)(3))(2)(micro-H)(2), 13. This complex contains a Ru(2)Pt(2) cluster with hydride ligands bridging two of the Ru-Pt bonds. The reaction of Fe(2)(CO)(9) with Pt(PBu(t)(3))(2) yielded the platinum-diiron cluster complex PtFe(2)(CO)(9)(PBu(t)(3)), 14, which is analogous to 11. All new complexes were characterized crystallographically. Molecular orbital calculations of 10 reveal an unusual delocalized metal-metal bonding system involving the Pd(PBu(t)(3)) groups and the Ru(2)(CO)(9) group.     

Enamines of 1,3-dimethylbarbiturates and their symmetrical palladium(II) complexes: synthesis,characterization and biological activity

Transition Metal Chemistry - Three 1,3-dimethylbarbiturate-enamine derivatives and their symmetrical palladium(II) complexes were prepared and characterized by spectroscopic methods. In addition,...     

Phosphinic platinum complexes with 8-thiotheophylline derivatives: synthesis, characterization, and antiproliferative activity

The platinum mixed-phosphine complexes (SP-4,2)-[PtCl(8-MTT)(PPh3)(PTA)] (2) and cis-[Pt(8-MTT)2(PPh3)(PTA)] (3) (MTTH2 = 8-(methylthio)theophylline, PTA = 1,3,5-triaza-7-phosphaadamantane) have been prepared from the precursor cis-[PtCl2(PPh3)(PTA)] (1), which has been fully characterized by X-ray diffraction determination. Antiproliferative activity tests indicated that the presence of one lipophilic PPh3 and one hydrophilic PTA makes 1-3 more active than the analogues bearing two PPh3 or two PTA. The reactivity of cis-[PtCl2(PPh3)2], cis-[PtCl2(PTA)2], and cis-[PtCl2(PPh3)(PTA)] with the bis(thiopurines) bis(S-8-thiotheophylline)methane (MBTTH2), 1,2-bis(S-8-thiotheophylline)ethane (EBTTH2), and 1,3-bis(S-8-thiotheophylline)propane (PBTTH2) has also been investigated. New binuclear complexes have been prepared and identified by spectroscopic techniques and their antiproliferative activities on T2 and SKOV3 cell lines evaluated.     

Synthesis and characterization of palladium(II) and platinum(II) complexes with ferrocenylimidazole

The synthesis and characterization of ferrocenylimidazole complexes of platinum(II) and palladium(II) are described. Reaction of ferrocenylimidazoles with K₂MCl₄ (M = Pd, Pt) using a biphasic system of dichloromethane and ethanol/water provided the corresponding complexes 2a–2j in good yields. New synthetic routes for the synthesis of ferrocenylbenzylethers 2k–2o, bis(4-ferrocenylbenzyl)carbonate [2p] and 4-ferrocenylbenzylacetate [2q] are also described. These products were obtained by the reaction of 4-ferrocenylbenzyl-1H-imidazole-carboxylate and K₂PtCl₄ under various conditions. Compounds 2k–2o were also obtained by alternative routes which do not involve the use of a platinum salt. The crystal structures of 2b, 2q and plausible mechanisms for the formation of 2k, 2p and 2q are reported.     

New fac-tricarbonyl rhenium(I) semicarbazone complexes: synthesis,characterization, and biological evaluation

Expanding our previous work on salicylaldehyde semicarbazone metal complexes as prospective anti-trypanosomal agents, five new fac-Re^I(CO)₃-containing complexes with ligands of this semicarbazone series were synthesized and characterized. An atypical coordination mode of these potentially tridentate ligands through only the carbonylic oxygen and the azomethine nitrogen (the so-called N,O fashion) was demonstrated by IR spectroscopy and supported by theoretical calculations. Three of the compounds showed moderate in vitro anti-Trypanosoma cruzi activity and increased activity with respect to the corresponding free ligands. The brominated ligands, 5-bromo-2-hydroxybenzaldehyde semicarbazone (L2) and 5-bromo-2-hydroxy-3-methoxybenzaldehyde semicarbazone (L5), led to the most active rhenium(I) complexes. These compounds are among the few reported examples of rhenium complexes bearing in vitro activity against T. cruzi.