Synthesis and structure of bis(2-methylquinoline-8-selenolato)platinum

Bis(2-methylquinoline-8-selenolato)platinum was synthesized and studied by X-ray diffraction structural analysis. The diffraction results were compared with the data for bis(quinoline-8-selenolato)platinum, bis(2-methylquinoline-8-thiolato)platinum, and bis(quinoline-8-thiolato)-platinum. The effect of the 2-methyl group on the structure of the complex and its coordination sphere (Pt + 2Se + 2N) was discussed.     

An unusual six-co-ordinate platinum(II) complex containing a neutral I2 ligand

The present paper deals with a rare platinum(II) complex containing the kappa-I2 ligand, which is an unusual example of a six-co-ordinated octahedral platinum(II) complex.     

Rearrangement of a (dithiolato)platinum(II) complex formed by reaction of cyclic disulfide 7,8-dithiabicyclo[4.2.1]nona-2,4-diene with a platinum(0) complex: oxidation of the rearranged (dithiolato)platinum(II) complex

Reaction of the title bicyclic disulfide 16 with [(Ph3P)2Pt(eta2-C2H4)] (2) yielded the corresponding (dithiolato)platinum(II) complex 17 by oxidative addition. The initial product 17 isomerized at room temperature in a [1,5]-sulfur rearrangement to give another (dithiolato)platinum(II) complex 18 in high isolated yield. Oxidation reactions of 18 with dimethyldioxirane (DMD) provided (sulfenato-thiolato)platinum(II) 23, (sulfinato-thiolato)platinum(II) 24, (sulfenato-sulfinato)platinum(II) 25, and (disulfinato)platinum(II) 26 complexes, the structures of which were elucidated by NMR spectroscopy and X-ray crystallography. The oxidation process took place regioselectively in the first step and chemoselectively in the second. The selectivities are discussed.     

Reaction of (R)-(-)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato)platinum( II) with guanosine

The reaction of a new antitumor platinum complex, (R)-(-)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato++ +)platinum(II) (1) with guanosine at room temperature in an aqueous solution was followed by proton nuclear magnetic resonance (1H-NMR) spectroscopy and high performance liquid chromatography (HPLC) at intervals. Both techniques showed that a new compound was formed by displacement of the 1,1-cyclobutanedicarboxylate moiety of 1 with two guanosines, and its 1H-NMR spectrum and HPLC chromatogram were proved to be identical with those of [(R)-(-)-2-aminomethylpyrrolidine]bis(N7-guanosine)platinum(II) (2), which was obtained upon successive treatment of (R)-(-)-2-aminomethylpyrrolidinedichloroplatinum(II) (3) with AgNO3 and 2 mol eq of guanosine in water. The binding sites of the platinum to the two guanosine moieties in 2 were confirmed by the pH dependence of the two G-H8 signals.     

Synthesis, structure and antitumor activity of a water-soluble platinum complex, (1R,3R,4R,5R)-(-)-quinato(1R,2R-cyclohexanediamine)platinum (II).

The reaction of dihydroxo(1R,2R-cyclohexanediamine)platinum(II) with (-)-quinic acid gave a water soluble complex, (-)-quinato(1R,2R-cyclohexanediamine)platinum(II). The crystal structure of the complex was determined by X-ray analysis. The data indicate a chelation of the alpha-hydroxycarboxylic acid part of quinic acid to platinum(II). The complex shows moderate antitumor activity against murine leukemia L1210 at high doses (T/C x 100 = 179% at a dose of 200 mg/kg).     

Organoplatinum(II) complexes containing chelating or bridging bis(N-heterocyclic carbene) ligands: formation of a platinum(II) carbonate complex by aerial CO2 fixation

The preparation of two new bis(N-heterocyclic carbene) platinum(II) complexes, in which NHC rings are joined by a CH(2) linker group, is described. While, the chelate complex [PtMe(2)(bis-NHC1)], 1, was formed with large tert-butyl wingtips, the iso-propyl N-substituent analogue favors formation of the cluster complex [Pt(2)Me(4)(μ-SMe(2))(μ-bis-NHC2)](2)(μ-Ag(2)Br(2)), 2, in which two binuclear platinum(II) complexes are linked together by an Ag(2)Br(2) unit. The chelating platinum complex 1 undergoes aerial CO(2) fixation and forms platinum(II) carbonate complex [Pt(CO(3))(bis-NHC1)], 3.     

Carbonyl complexes of platinum(0): synthesis and structure of [(Cy3P)2Pt(CO)] and [(Cy3P)2Pt(CO)2

The platinum(0) monocarbonyl complex, [(Cy(3)P)(2)Pt(CO)], was synthesized by reaction of [(Cy(3)P)(2)Pt] with [(η(5)-C(5)Me(5))Ir(CO)(2)] and subsequent irradiation. X-ray structure analysis was performed and represents the first structural evidence of a platinum(0) monocarbonyl complex bearing two free phosphine ligands. Its corresponding dicarbonyl complex [(Cy(3)P)(2)Pt(CO)(2)] was synthesized by treatment of [(Cy(3)P)(2)Pt] with CO at -40 °C and confirmed by X-ray structure analysis.     

双马来腈二亚胺合铂与DNA的作用

本文以紫外-可见光谱、荧光光谱及黏度法研究了双马来腈二亚胺合铂与DNA的作用。紫外-可见光谱的研究表明,与DNA作用后,双马来腈二亚胺合铂在可见区的吸收显示出了减色效应,并伴随着吸收峰的蓝移。Scatchard图的分析结果表明,双马来腈二亚胺合铂与DNA的作用位点与溴化乙锭不同。黏度法实验表明,双马来腈二亚胺合铂与DNA作用后降低了DNA的相对黏度。这些研究结果表明,双马来腈二亚胺合铂以静电作用方式与DNA结合。本研究有助于深入理解双马来腈二亚胺合铂的作用机理并开发这种潜在的新型光动力治疗剂。     

Novel luminescent hexanuclear platinum(II) alkynyl complex: molecular lego from a face-to-face dinuclear platinum(II) building block

A novel luminescent hexanuclear platinum(II) complex, [Pt(2)(mu-dppm)(2)(C[triple bond]CC(5)H(4)N)(4)[Pt(trpy)](4)](CF(3)SO(3))(8) (trpy = 2,2':6',2'-terpyridine), was successfully synthesized by using the face-to-face dinuclear platinum(II) ethynylpyridine complex [Pt(2)(mu-dppm)(2)(C[triple bond]CC(5)H(4)N)(4)] as the building block.     

Ethylenebis(triphenylphosphine)platinum as a probe for niobium-mediated diphosphorus chemistry

Ethylenebis(triphenylphosphine)platinum is used as a trap for the P2-containing molecule W(CO)5(P2), which is eliminated at room temperature from a niobium-complexed diphosphaazide ligand. The rate of W(CO)5(P2) elimination is unaffected by the presence of the platinum species. Attempts to generate and trap free P2 with the platinum ethylene complex were hindered by the direct reaction between the platinum starting material and the P2 generator, (Mes*NPP)Nb(N[Np]Ar)3. In this case, reductive cleavage of the P-P bond in the diphosphaazide ligand is induced by platinum coordination, resulting in the formation of a trimetallic system with two bridging, three-coordinate phosphorus atoms.     

Structural features of a new dinuclear platinum(II) complex with significant antiproliferative activity

A novel dinuclear platinum(II) complex, [Pt(2)-N,N'-bis(2-dimethylaminoethyl oxamide)Cl(4)], showing peculiar structural features, has been prepared and characterized. X-ray diffraction data reveal that the two platinum ions are simultaneously bound to the N,N'-bis(2-dimethylaminoethyl) oxamide ligand, on opposite sides. The coordination environment of both platinum centers is square planar, with identical NOCl(2) donor sets. The complex is poorly soluble within a physiological buffer but moderately soluble in DMSO. Preliminary in vitro studies point out that this dinuclear platinum complex exhibits significant growth-inhibiting properties on a panel of cultured human tumor cell lines, although less pronounced than those of cisplatin.     

Cyclometallated platinum(II) complexes: oxidation to, and C-H activation by, platinum(IV)

A series of cyclometallated phenylpyridine platinum(II) complexes have been synthesised with a systematic variation in both the phenylpyridine and the ancillary ligand. Oxidation of one of the cyclometallated species leads to a number of isomeric platinum(IV) complexes, all of which eventually isomerize to a single compound. The route to these new compounds has been demonstrated to involve an initial slow oxidation followed by a rapid C-H activation to give doubly cyclometallated complexes. The solid state structures of a number of both the platinum(II) and the platinum(IV) species have been solved; many of the structures exhibited extended interactions that result in complex three dimensional packing.     

Luminescent square-planar platinum(II) complexes with tridentate 3-bis(2-pyridylimino)isoindoline and monodentate N-heterocyclic ligands

A series of platinum(II) complexes with 1,3-bis(2-pyridylimino)isoindoline (BPI) derivatives were prepared by substitution of the coordinated Cl in the precursor complex Pt(BPI)Cl with a N-heterocyclic ligand such as pyridine, phthalazine or phenanthridine. These complexes display orange to red luminescence in fluid dichloromethane solutions and in the solid states at room temperature. The photophysical properties were tuned by introducing electron-withdrawing -NO(2) or electron-donating -NH(2) to the BPI ligand. The DFT computational studies suggest that the emission in the N-heterocyclic ligand substituted platinum(II) complexes originates mainly from the (3)[π→π*(BPI)] (3)IL triplet excited state, mixed with some (3)[dπ(Pt)→π*(BPI)] (3)MLCT character. Compared with the precursor Pt(BPI)Cl, both the low-energy absorption and the emission in the N-heterocyclic ligand substituted platinum(II) complexes exhibits a distinct blue-shift due to an obviously enhanced contribution from the (3)IL state and a reduced (3)MLCT character.     

Crystal structure of trans-dibromobis(triphenylphosphine)platinum(II).

Crystal structure of trans-dibromobis(triphenylphosphine)platinum(II) was determined by X-ray-crystallography. The complex crystallizes on an inversion center in distorted square planar coordination around platinum with triphenylphosphine ligands in trans positions to each other and with two molecules of dichloromethane as solvate.     

cis-Bis(2-Phenylpyridine)platinum(II) (CBPPP). A simple molecular platinum compound preliminary communication

The deprotonated 2-phenylpyridine forms a 2:1 chelate with platinum(II) in cis-configuration, which exists as a dimer in a molecular solid.     

Adsorptive stripping voltammetric measurements of trace amounts of platinum(II) and ruthenium(III) in the presence of 1-(2-pyridylazo)-2-naphthol

An extremely sensitive stripping voltammetric procedure for low level measurements of platinum (II, IV) or ruthenium (III, IV) is reported. The method is based on the interfacial accumulation of the platinum (II) or ruthenium (III)-1-(2-pyridylazo)-2-naphthol complex on the surface of a hanging mercury drop electrode, followed by the reduction of the adsorbed complex during the cathodic scan. The peak potential was found to be –0.8 V vs. Ag/AgCl electrode and the reduction current of the adsorbed complex ions of platinum (II) or ruthenium (III) was measured by differential pulse cathodic stripping voltammetry. The optimum experimental conditions were: 1.5×10^–7 mol/l of 1-(2-pyridylazo)-2-naphthol solution of pH 9.3, preconcentration potential of –0.2 V, accumulation time of 3 min and pulse amplitude of 50 mV with 4 mV s^–1 scan rate in the presence of ethanol-water (30% v/v) — sodium sulphate (0.5 mol/l). Linear response up to 6.4 × 10^–8 and 5.1 × 10^–8 mol/l and a relative standard deviation (at 1.2×10^–8 mol/l) of 2.4 and 1.6% (n=5) for platinum (II) and ruthenium (III) respectively were obtained. The detection limits of platinum and ruthenium were 3.2×10^–10 and 4.1×10^–10 mol/l, respectively. The electronic spectra of the Pt(II) — PAN and Ru(III) — PAN complexes were measured at pH 9.3 and the stoichiometric ratios of the complexes formed were obtained by the molar ratio method. The effects of some interfering ions on the proposed procedure were critically investigated. The method was found suitable for the sub-microdetermination of ruthenium (IV) and platinum (IV) after their reduction to ruthenium (III) and platinum (II) with sulphur dioxide in acid media. The applicability of the method for the analysis of binary mixtures of ruthenium (III) and (IV) or platinum (II) and (IV) has also been carried out successfully. The method is simple, rapid, precise, and promising for the determination of the tested metal ions at micro-molar concentration level.     

Sulfur- and oxygen-containing platinum(II) complex

Russian Journal of General Chemistry - Mixed-ligand platinum(II) complex with ethylenedithiodiacetic acid (HSSH) and thioglycolic acid has been synthesized. Ethyleneditiodiacetate is coordinated to...     

Diastereoselective assembling of 21-C-alkylated nickel(II) complexes of inverted porphyrin on a platinum(II) template

Reaction of 21-C-methyl and 21-C-benzyl nickel(II) complexes of inverted meso-tetratolylporphyrin with platinum(II) dichloride or its bis(benzonitrile) complex yields a chloroplatinum(II) species containing two nickel(II) carbaporphyrinoids in a cis arrangement. One of the carbaporphyrinoids coordinates to the platinum ion with the external nitrogen while the other is bound with the external nitrogen and one ortho-carbon of the adjacent meso-aryl ring. The reaction is highly chemoselective. (1)H and (13)C NMR experiments in solution show the diastereoselectivity of the reaction. Single-crystal X-ray data confirm the presence of the diastereomer with opposite configurations of the Ni(II)-coordinated carbons in the subunits of the dimer. Cyclovoltammetric measurements reveal an anodic shift of the nickel(II) oxidation potentials of dimers with respect to those of the parent monomers and two different reduction couples. Reaction of unsubstituted inverted porphyrin with Pt(PhCN)(2)Cl(2) in chlorobenzene yields a monomeric platinum(II) complex of inverted porphyrin. This complex displays a markedly upfield (195)Pt NMR shift compared to tetraphenylporphyrinatoplatinum(II). Under strongly basic conditions deprotonation of the external nitrogen of inverted porphyrin and both electrochemical and chemical oxidation of platinum(II) center are observed.     

White emission from dinuclear cyclometalated platinum(II) complex in single-emitting layer PLEDs

A dinuclear platinum(II) complex of (dfppy)₂Pt₂(dipic) has been prepared, where dfppy is 2,4-difluorophenylpyridine and dipic is a biphenyl-bridged bi-picolinic acid derivative. Its physical and optoelectronic properties, as well as molecular orbitals calculation have been investigated and compared with those of its mono-nuclear (dfppy)Pt(pic) complex. Both platinum(II) complexes exhibited almost identical photoluminescence (PL) spectra with deep blue emission in dilute dichloro-methane (10⁻⁵ M) and different PL spectra with red emission in their neat films. Stable white emissions were obtained in the (dfppy)₂Pt₂(dipic)-doped polymer light-emitting devices using a blend of poly(vinylcarbazole) and 2-(4-biphenyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole as a host matrix at dopant concentrations from 1 wt % to 10 wt %. In contrast, the (dfppy)Pt(pic)-doped devices exhibited orange-red emissions in the same device configuration. It indicates that dinuclear platinum(II) complex with a non-planar structure is an effective way to control formation excimers of platinum(II) complex and get white-emitting PLEDs with single dopant.     

Synthesis and characterization of a platinum(II) complex with N-acetyl-L-cysteine

Synthesis and spectroscopic studies in the solid-state of a platinum(II) complex with N-acetyl-L-cysteine are described. Elemental analyses are consistent with composition Pt₂(C₅H₈NO₃S)₄ · 3H₂O. Solid-state ¹³C NMR, infrared, and U-Vis spectroscopic results are consistent with coordination of the ligand to platinum(II) through sulfur. Thermal analyses confirmed water in the complex composition. Final residue of the thermal treatment was identified by powder X-ray diffractometry as metallic platinum.