Reaction Of Pt Research Articles

Reaction of the PtIII complex, [Pt2(μ-NHCOMe)4Cl2], with 1,10-phenanthroline and solid-state thermolysis of 1,10-phenanthroline-containing platinum blues

Platinum blues with the composition Pt(phen)(NHCOMe)2X (phen is 1,10-phenanthroline, X = NO3 −, CF3SO3 −, or Cl−), were synthesized starting from the complex [Pt2(NHCOMe)4Cl2]. The resulting compounds apparently have a polymeric structure with metal centers in different valence states. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with H2O affords crystalline binuclear acetamidate [PtIII 2(phen)2(μ-NHCOMe)2(NHCOMe)2](NO3)2, whose structure was determined by X-ray diffraction. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with HCF3SO3 leads to the decomposition of the starting compound, the reduction of the Pt atoms, and the formation of the complex [PtII 2(phen)4](CF3SO3)4. The thermal decomposition of the resulting complexes, as well as the complexes [(phen)Pt-(μ-NHCOMe)2Pt(phen)]2(NO3)4 and [Pt(phen)Cl2], under an inert atmosphere was studied by DSC and TGA. Metallic platinum nanopowders are thermal decomposition products of the complexes under study.

A Cationic NCN Pincer Platinum(II) Aquo Complex with a Bis(imidazolinyl)phenyl Ligand: Studies toward its Synthesis and Asymmetric Friedel–Crafts Alkylation of Indoles with Nitroalkenes

Studies toward the synthesis and characterization of a cationic NCN pincer platinum(II) aquo complex with a chiral bis(imidazolinyl)phenyl (Phebim) ligand are reported. During these studies, the new symmetrical Phebim-H ligands 1c,d and unsymmetrical hybrid oxazoline–imidazoline ligands 6a–c, as well as the related neutral symmetrical NCN pincer Pt(II) complexes 2b–d and 3a–d and unsymmetrical NCN′ pincers 7a,b and 8c have been isolated and characterized. Despite considerable attempts, only one of the expected cationic chiral NCN pincer Pt(II) complexes (4), which contains water as an exchangeable neutral ligand for the Pt(II) center, was obtained in pure form from the reaction of the neutral Pt–I complex 3a with AgOTf in wet CH2Cl2 at room temperature. In contrast, the cationic Pt(II) pyridine complexes 5a,c could be easily prepared in high yields from the reaction of the neutral Pt–Cl complexes 2a,c with AgOTf in the presence of pyridine in CH2Cl2 at room temperature. The molecular structures of the neu...

Mechanistic studies on the reactions of platinum(ii) complexes with nitrogen- and sulfur-donor biomolecules

A brief overview of mechanistic studies on the reactions of different Pt(II) complexes with nitrogen- and sulfur-donor biomolecules is presented. The first part describes the results obtained for substitution reactions of mono-functional Pt(II) complexes with different biomolecules, under various experimental conditions (temperature, pH and ionic strength). In addition, an overview of the results obtained for the substitution reactions of bi-functional Pt(II) complexes, analogous to cisplatin, with biomolecules is given. The last part of this report deals with different polynuclear Pt(II) complexes and their substitution behaviour with different biomolecules. The purpose of this perspective is to improve the understanding of the mechanism of action of Pt(II) complexes as potential anti-tumour drugs in the human body.

Molecular selective photocatalytic decomposition of alkylanilines by crystalline TiO2 particles and their nanocomposites with mesoporous silica

Molecular selective photocatalytic decomposition of alkylanilines in water was investigated by using crystalline TiO2 particles (P-25) and their nanocomposites with mesoporous silica. In the nanocomposites, pre-formed TiO2 particles were embedded into surfactant-templated mesoporous silica with tuned pore sizes (1.4–5.3 nm) as described in our previous reports (Chem. Commun. 2005, 2131–2133; J. Mater. Chem. 2011, 21, 12117–12125). Contrary to the generally accepted knowledge of TiO2 photocatalysts, pristine TiO2 particles showed molecule selective photocatalysis: decomposition of 4-n-heptylaniline (NHA) was much faster than that of 4-n-butylaniline (NBA) or p-toluidine (4-methylaniline, PT) in a mixed aqueous solution. After NHA had almost disappeared, decomposition of NBA accelerated. When the TiO2 particles were surrounded by mesoporous silica, the molecular selectivity was strongly modified: the nanocomposites showed high molecular selectivity for NBA decomposition and the reaction of PT was considerably suppressed. The origin of molecular selectivity can basically be ascribed to preferential molecular adsorption, and the difference in selectivity between alkylanilines and alkylphenols is discussed in terms of the interaction of the molecules with the nanocomposite surfaces.

Redox processes in photochemistry of Pt(iv) hexahaloid complexes

Ultrafast pump–probe spectroscopy (λpump = 405 nm) was applied to study the primary photochemical processes for PtCl62− and PtBr62− complexes in aqueous and alcohol solutions. For PtCl62−, an intermediate with a lifetime of ca. 200 ps was registered and identified as an Adamson radical pair [PtIIICl52−⋯Cl˙]. The transformations of the primary intermediate give rise to successive formation of different Pt(III) species. The reactions of Pt(III) results in chain photoaquation in aqueous solutions and reduction of Pt(IV) to Pt(II) in alcohol solutions. For PtBr62− complex, the previously reported (I. L. Zheldakov, M. N. Ryazantsev and A. N. Tarnovsky, J. Phys. Chem. Lett., 2011, 2, 1540; I. L. Zheldakov, PhD thesis, Bowling Green State University, 2010) formation of active 3PtBr5− intermediate is followed by very fast (15 ps) aquation of Pt(IV) in aqueous solutions and parallel reactions of solvation and reduction of Pt(IV) to Pt(II) in alcohol solutions. All the processes in alcohols are finished within 0.5 ns. The data of ultrafast experiments are supported by nanosecond laser flash photolysis and stationary photolysis.

Oxygen Reduction Reaction of Pt Supported on Y-Doped SrTiO3

Oxygen Reduction Reaction of Pt Supported on Y-Doped SrTiO3

Toward heteronuclear supramolecular architectures of pyridine-4-thiolate

The reaction of Pt(d-t-bpy)(S-4-py)2 (1; d-t-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine, S-4-py = pyridine-4-thiolate) with ZnX2 (X = Cl, Br, I) gave the respective heteronuclear metallocycles, [Pt(d-t-bpy)(S-4-py)2(ZnX2)]2 (X = Cl 2, Br 3, and I 4). In particular, the presence of weak intermolecular Pt(II)⋯Pt(II) (3.374 and 3.453 A for 2; 3.364 and 3.452 A for 3) and π⋯π (3.279 and 3.490 A for 2; 3.574 and 3.793 A for 3) interactions makes the heteronuclear metallocycles cooperatively stack to form a monohelical chain, and four monohelices are further stacked to give a novel bundle-of-quadruple-monohelix through nonclassical hydrogen bonding. However, 4 having only π⋯π interactions, possibly due to the larger atom size for I, cannot form a similar structural framework as those of 2 and 3. Hence, the presence of weak Pt(II)⋯Pt(II) interactions seems to play a vital role for the formation of such a novel structural motif. For the NO3 complex, [Pt2(d-t-bpy)2(S-4-py)4(Zn(NO3))2(μ-O)]n (5), a one-dimensional ladder structure is formed instead of a heteronuclear metallocycle. Therefore, a delicate anion-induced assembly has been demonstrated. In addition, the emissions of 2–5 are quite similar to that of Pt(d-t-bpy)(S-4-py)2, which has been assigned to a ligand-to-ligand charge-transfer (LLCT) transition, indicating that the coordination to Zn(II) ions through pyridyl-4-thiolate ligands of Pt(d-t-bpy)(S-4-py)2 cannot cause a significant effect on their LLCT emissions.

Adsorption of Pd(II), Pt(IV), and Rh(III) on a Ligand Encapsulated Polymer Resin Assisted by Thermal Heating or Microwave Irradiation

A new chelating resin (R-N resin) was prepared through the encapsulation of linear poly(octadecylvinyl−maleic anhydride) into a porous polyacrylate support (Amberlite XAD−7) with subsequent grafting of 2−aminomethylpyridine. Adsorption characteristics of the chelating resin for platinum group metals (Pd(II), Pt(IV), Rh(III)) were examined with respect to the adsorption rate and dependence on pH and temperature. The adsorption reaction of Pd(II) and Pt(IV) at pH 2 in the presence of Cl− ion (0.1 M) was exothermic, whereas that of Rh(III) was endothermic. Ion exchange reaction by electrostatic attraction between the protonated ligand with [PdCl4]2− and [PtCl6]2− is predominant for the adsorption of Pd(II) and Pt(IV) at pH 2.0. While Rh(III) was retained by a complex formation from pH 2.0 to pH 6.5, adsorption of Rh(III) was remarkably accelerated by microwave irradiation: more than 91% of Rh(III) was retained for 1 h, while it was less than 50% by conventional heating. Repeated use of resin after regeneration was also demonstrated.

Low-Energy Electron-Induced Decomposition and Reactions of Adsorbed Tetrakis(trifluorophosphine)platinum [Pt(PF3)4

The effect of ∼500 eV electrons on nanometer-thick films of the platinum precursor tetrakis(trifluorophosphine)platinum [Pt(PF3)4] has been studied in situ under ultra-high-vacuum (UHV) conditions using a combination of X-ray photoelectron spectroscopy (XPS), mass spectrometry (MS), and high-resolution electron energy loss spectroscopy (HREELS). Electron irradiation of adsorbed Pt(PF3)4 molecules initially proceeds through a single Pt—P bond-cleavage event and the ejection of one PF3 ligand, analogous to the electron-stimulated reactions of Pt(PF3)4 in the gas phase. The electron-stimulated deposition cross section of Pt(PF3)4, σPt(PF3)4, is governed by the rate of this initial Pt—PF3 cleavage event, which is calculated to be ∼2.5 × 10–15 cm2 at an incident electron energy of 500 eV. In contrast to the initial deposition step, subsequent electron-stimulated reactions of the surface-bound Pt(PF3)3 intermediate occur exclusively through P—F bond cleavage and the release of fluorine into the gas phase. In this second phase of the decomposition process, oxygen uptake into the film is observed because of reactions between water vapor and the coordinatively unsaturated phosphorus atoms formed by P—F bond cleavage. Electron-beam-induced deposition (EBID) of Pt(PF3)4 was also performed by electron irradiating a substrate at room temperature and at higher electron fluxes, in the presence of a constant partial pressure of Pt(PF3)4. The absence of fluorine in these films underscores the role of electron-stimulated P—F bond cleavage, whereas the absence of oxygen highlights the important role that deposition conditions (e.g., substrate temperature and background gas composition) play in determining the ultimate composition of typical EBID films.

Highly Luminescent Mixed-Metal Pt(II)/Ir(III) Complexes: Bis-Cyclometalation of 4,6-Diphenylpyrimidine As a Versatile Route to Rigid Multimetallic Assemblies

The proligand 4,6-di-(4-tert-butylphenyl)pyrimidine LH(2) can undergo cycloplatination with K(2)PtCl(4) at one of the two aryl rings to give, after treatment with sodium acetylacetonate, a mononuclear complex Pt(N^C-LH)(acac) (denoted Pt). If an excess of K(2)PtCl(4) is used, a dinuclear complex of the form [Pt(acac)](2){μ-(N^C-L-N^C)} (Pt(2)) is obtained instead, where the pyrimidine ring acts as a bridging unit. Alternatively, the mononuclear complex can undergo cyclometalation with a different metal ion. Thus, reaction of Pt with IrCl(3)·3H(2)O (2:1 ratio) leads, after treatment with sodium acetylacetonate, to an unprecedented mixed-metal complex of the form Ir{μ-(N^C-L-N^C)Pt(acac)}(2)(acac) (Pt(2)Ir). The mononuclear iridium complex Ir(N^C-LH)(2)(acac) (Ir) has also been prepared for comparison. The UV-visible absorption and photoluminesence properties of the four complexes and of the proligand have been investigated. The complexes are all highly luminescent, with quantum yields of around 0.5 in solution at room temperature. The introduction of the additional metal centers is found to lead to a substantial red-shift in absorption and emission, with λ(max) in the order Pt < Pt(2) < Ir < Pt(2)Ir. The trend is interpreted with the aid of electrochemical data and density functional theory calculations, which suggest that the red-shift is due primarily to a progressive stabilization of the lowest unoccupied molecular orbital (LUMO). The radiative decay constant is also increased. This versatile design strategy may offer a new approach for tuning and optimizing the luminescence properties of d-block metal complexes for contemporary applications.

Study of Platinum Dissolution Mechanism Using a Highly Sensitive Electrochemical Quartz Crystal Microbalance

Abstract Platinum (Pt) dissolution during oxidation/reduction cycle in various potential cycle ranges and in various pHs of the oxygen-saturated and deaerated H2SO4 and HClO4 electrolyte solutions was monitored by the highly sensitive electrochemical quartz crystal microbalance (EQCM) system. It was found that the Pt mass reduction depended on the potential cycle range and pH of the electrolyte solution with dissolved oxygen. Based on these results, it can be suggested that the dissolution of Pt requires one proton per one Pt and that it also requires dissolved oxygen, and then we can conclude that the dissolution reaction of Pt is as followings; PtO + H+ + 1/2O2 + H2O → Pt(OH)3+ and/or PtOH + H+ + 3/4O2 + 1/2H2O → Pt(OH)3+.

Design, synthesis and reactivity with dichloro-bis(triphenylphosphine) platinum(II) of two triazenide compounds

In the presence of sodium nitrite, the reaction of methyl anthranilate and 2-aminopyridine or o-aminobenzoic acid gives two triazenes, 1-[(2-carboxymethyl)benzene]-3-[2-pyridine]triazene (HL) and 1-[(2-carboxymethyl)benzene]-3-[o-aminobenzoic acid]triazene (H 2L′), respectively. In the presence of Et 3N, the reaction of Pt(PPh 3) 2Cl 2 and HL or H 2L′ produces two triazenido platinum(II) complexes, Pt(PPh 3) 2(L)Cl ( 1) and Pt(PPh 3) 2(L′) (2), respectively, which have been characterized by X-ray crystallography, 31P NMR spectra, UV–Vis spectra, emission spectra and cyclic voltammetry. When excited at 310 nm, complexes 1 and 2 show luminescence at 432 and 442 nm, respectively, which is consistent with the trend of the lowest-energy absorption wavelengths of 1 (376 nm) and 2 (379 nm). Complexes 1 and 2 exhibit one or two redox waves and follow the order 1 (0.97 V) → 2 (0.89 and 0.07 V), which is also in accordance with the trend of the lowest-energy absorption spectra of 1 (376 nm) and 2 (379 nm).

Displacement reaction of Pt on carbon-supported Ru nanoparticles in hexachloroplatinic acids

The displacement reaction of Pt on Ru to form a Ru core and Pt shell (Ru@Pt) bimetallic structure is investigated by immersing the carbon-supported Ru nanoparticles in hexachloroplatinic acids with pH of 1, 2.2, and 8, followed by a hydrogen reduction treatment. Results from inductively coupled plasma mass spectrometry suggest that the dissolution of Ru is mostly caused by the reduction of Pt cations. Images from transmission electron microscopy demonstrate a uniform distribution of Ru@Pt in size of 3–5nm. Spectra from X-ray absorption near edge structure and extended X-ray absorption fine structure confirm that the pH value of hexachloroplatinic acid determines the type of ligands complexing the Pt cations that affects their activity and consequently the severity of displacement reaction and alloying degree of Ru@Pt nanoparticles. As a result, the samples from pH 1 bath reveal a desirable core–shell structure that displays a reduced onset potential in CO stripping and stable catalytic performance for H2 oxidation while the samples from pH 8 bath indicate the formation of Pt clusters on the Ru surface that leads to poor CO stripping and H2 oxidation characteristics.

Photoreaction pathways for the anticancer complex trans,trans,trans-[Pt(N3)2(OH)2(NH3)2

The photodecomposition of the anticancer complex trans,trans,trans-[Pt(N(3))(2)(OH)(2)(NH(3))(2)] in acidic aqueous solution, as well as in phosphate-buffered saline (PBS), induced by UVA light (centred at λ = 365 nm) has been studied by multinuclear NMR spectroscopy. We show that the photoreaction pathway in PBS, which involves azide release, differs from that in acidic aqueous conditions, under which N(2) is a major product. In both cases, a number of trans-{N-Pt(II/IV)-NH(3)} species were also observed as photoproducts, as well as the evolution of O(2) and release of free ammonia with a subsequent increase in pH. The results from this study illustrate that photoinduced reactions of Pt(IV)-diazido derivatives can lead to novel reaction pathways, and therefore potentially to new cytotoxic mechanisms in cancer cells.

Synthesis, characterization, and crystal structure of cis‐[Pt(Me)2{PPh2(OMe)}2] and the conversion into cis‐[Pt(OH2)2{PPh2(OMe)}2][OTf]2

AbstractThe reaction of Pt(Me)2 (cod) (cod = η2:η2‐1,5‐cyclooctadiene) with 2 equivalents of PPh2(OMe) afforded a bis(phosphinite)platinum complex cis‐[Pt(Me)2{PPh2(OMe)}2] (1). The reaction of 1 with trifluoromethanesulfonic acid HOTf (OTf‐ = CF3O2 SO‐) and then H2O produced a di(aqua)platinum complex cis‐[Pt(OH2)2{PPh2(OMe)}2][OTf]2 (2). New complexes 1 and 2 were fully characterized using NMR measurements and elemental analyses. Furthermore, structures of 1 and 2 were determined by single crystal X‐ray diffraction studies. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:371–376, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20692

Diamidato-bis(diphenylphosphino) platinum(II) complexes: Synthesis, characterization, and reactivity in the presence of acid

The reaction of Pt(COD)Cl2, where COD is 1,5-cyclooctadiene, with one equivalent of a diamidato-bis(phosphino) Trost ligand ((R,R)-2=N,N′-bis(2-diphenylphosphino-1-benzoyl)-(1R,2R)-1,2-diaminocyclohexane, (R,R)-3=N,N′-bis(2-diphenylphosphino-1-naphthoyl)-(1R,2R)-1,2-diaminocyclohexane, or (±)-4=N,N′-bis(2-diphenylphosphino-1-benzoyl)-1,2-bis(aminobenzene)) in the presence of base afforded square planar diamidato-bis(phosphino) platinum(II) complexes (R,R)-2-Pt, (R,R)-3-Pt, (±)-4-Pt. Characterization of all complexes included the solution and solid state structure determination of each complex based on multinuclear NMR and X-ray analyses, respectively. Stability of the complexes in acid was examined on addition of HCl to (R,R)-2-Pt in chloroform and compared to the unreactive nature of the similar diamidato-bis(phosphino) complex 1-Pt (1=1,2-bis-N-[2′-(diphenylphosphino)benzoyl]diamino-benzene) in the presence of acid. Protonation of the bound amidato nitrogen atoms of (R,R)-2-Pt was observed along with decoordination of the nitrogen atoms from the platinum(II) center producing (R,R)-2-PtCl2 in quantitative yield by NMR analysis. Confirmation of the product was made on comparison of the NMR spectra to that of authentic (R,R)-2-PtCl2 prepared on reaction of Pt(COD)Cl2 with (R,R)-2 in CH2Cl2 and characterized by single-crystal X-ray diffraction analysis and NMR spectroscopy. Results add to the knowledge of rich coordination chemistry of bis(phosphino) ligands with late transition metals, metal–amidato chemistry, and has implications in catalysis.

Reactions of a Phosphinoimino-thiazoline-Based Metalloligand with Organic and Inorganic Electrophiles and Metal-Induced Ligand Rearrangements

The reaction of the neutral Pt(II) bischelated complex cis-[Pt{Ph2PN···C···NCH2CH2S}2] ([Pt(2−H)2], 1; 2 = Ph2PNHC═NCH2CH2S, N-(diphenylphosphino)-thiazoline-2-amine) with the organic electrophile EtN═C═S yielded complex [Pt(2−H)(2−H·EtNCS)] (3) as a result of the nucleophilic attack of the coordinated 2-((diphenylphosphino)imino)thiazolidin-3-yl moiety on the heteroallene carbon atom and coordination of the sulfur atom to the metal. The reaction of 1 with [Cu(NCMe)4]PF6 also proceeded by nucleophilic attack of the P−N nitrogen atom on Cu(I) and afforded the coordination polymer [1·Cu]∞[PF6]∞ (4). The reaction of ligand 2 with NiBr2·xH2O resulted in a molecular rearrangement and afforded an unexpected pentacoordinated diamagnetic complex, [Ni(2){trans-Ph2PN═C−N(PPh2)CH2CH2S}Br]Br (6), which likely arises from a metal-templated ligand coupling in the presence of water acting as promoter. Complex 6 was evaluated as a precatalyst for ethylene oligomerization, showing good activities with EADC as cocatalyst. ...

Competitive activation of C–H and C–X bonds in gas phase reaction of Pt with CH 2FCl: A DFT study

The reaction of Pt ( 3D, 1S) with CH 2FCl was theoretically investigated using B3LYP method. The results indicate that C–F, C–Cl and C–H bonds can be activated by Pt atom. C–F bond activation has the highest energy barriers on both triplet and singlet surfaces (154.6 and 58.5 kJ/mol, respectively). C–Cl bond activation has lower barrier on triplet surface (98.3 kJ/mol), and it is barrierless process on singlet surface. C–H activation was only found on triplet surface with a barrier of 92.3 kJ/mol. Pathways for the HF, HCl and H 2-elimination were proposed and the experimentally observed product CHF–PtHCl is in fact reaction intermediate.

Reversible Hydrogen Activation by the Pt Complex Pt(SntBu3)2(CNtBu)2

The new platinum complex Pt(Sn(t)Bu(3))(2)(CN(t)Bu)(2)(H)(2), 1, was obtained in 32% yield from the reaction of Pt(COD)(2) with (t)Bu(3)SnH and CN(t)Bu at room temperature. Compound 1 is a mononuclear 18 electron platinum complex in an octahedral geometry which contains two Sn(t)Bu(3)'s, two CN(t)Bu's, and two hydride ligands. The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield the 16 electron complex Pt(Sn(t)Bu(3))(2)(CN(t)Bu)(2), 2. Compound 2 reacts with hydrogen at room temperature in solution and in the solid state to regenerate 1.

Mono‐ or Diplatinum Complexes Containing a π‐Conjugated Pentadiynyl Ligand

AbstractThe reaction of pentadiynyl halides XCH2C≡CC≡CPh (1) with equimolar amounts of Pt(C2H4)(PPh3)2 in C6D6 produced cis‐(PPh3)2PtX(η1‐CH2C≡CC≡CPh) (cis‐2) as a kinetic product. Complex cis‐2 isomerized to trans‐(PPh3)2PtX(η1‐CH2C≡CC≡CPh) (trans‐2) or trans‐(PPh3)2PtX[η1‐C(C≡CPh)=C=CH2] (trans‐3) under some reaction conditions. In contrast to the reaction of Pt(C2H4)(PPh3)2, treatment of 1 with Pt(PPh3)4 generated cationic platinacyclobutene [(PPh3)2Pt{η2‐CH2C(PPh3)=C(C≡CPh)}]+Cl– (5) together with cis‐2 and trans‐2. Moreover, 2 equiv. of Pt(C2H4)(PPh3)2 and 1 provided η1,η2‐coordinated diplatinum complex cis‐(PPh3)2PtCl[η1‐ CH2C≡C{(PPh3)2Pt(η2‐C≡CPh)}] (7) and/or metallacyclobutene diplatinum complex (PPh3)2Pt[η2‐CH2C{(PPh3)2PtCl}=C(C≡CPh)] (8). The coordination modes of these complexes depend on the ratio of pentadiynyl halide, Pt, and PPh3, as well as temperature and the nature of the solvents. Protonolysis of metallacyclobutene complexes 5 and 8 with HCl gave [cis‐(PPh3)2PtCl{η1‐C(C≡CPh)=C(PPh3)CH3}]+Cl– (9) and [(PPh3)2Pt{η3‐CH2{cis‐(PPh3)2PtCl}CCH(C≡CPh)}]+Cl– (10). Single‐crystal X‐ray diffraction analysis of 12 showed η3‐ and η1‐coordination structure.