Organoplatinum Complexes

A special issue of Inorganics (ISSN 2304-6740). This special issue belongs to the section "Organometallic Chemistry".

Deadline for manuscript submissions: closed (30 September 2014) | Viewed by 54327

Special Issue Editors

University of La Rioja, Logrono, La Rioja, Spain
Interests: synthesis of platinum group metal complexes, design of clusters and supramolecular networks stabilized by metal-metal and metal alkynyl bonds, study of their reactivity and photophysical behavior

Special Issue Information

Dear Colleagues,

The history of organoplatinum chemistry spans a long time period, from the early reports of Zeise or Pope and Peachey in the 19th century to today’s manifold applications of organoplatinum complexes or building blocks. On first view, the reason is simple: platinum, especially in the oxidation state +II provides very inert and thermodynamically stable Pt-C bonds and Pt2+ is (apart from Pd2+) the best ion to coordinate to olefin ligands.

Many applications of organoplatinum compounds utilize this robustness, which is even further elevated in cyclometalated compounds or units. In turn, the ease-of-use of the metalation reaction in activating H-C or X-C functions opens a vast field of synthetic organometallic chemistry. Organometallic platinum complexes or building blocks are highly amenable for use in the construction of supramolecular aggregates or hybrid materials. Such materials are often employed because of their easily tuneable (electro)luminescence. Here, the heavy and relativistic character of platinum, and thus the availability of triplet excited states, adds to the stable binding in such compounds. Pt-C bonds of organoplatinum complexes have also proved to be inert under physiological conditions; and the increased cytotoxicity compared to the established (non-organometallic) drug cisplatin and different toxicity mechanism, makes them interesting candidates for future anti-cancer drugs. On the other hand, chemists would not be chemists if they could not tune the bond strength and reactivity of Pt-C bonds, and thus render them more reactive. Therefore, in addition to the currently established use of organoplatinum complexes as slowed down models of platinum metal catalysed processes (note that palladium and rhodium are far less inert), organoplatinum complexes themselves have emerged on the scene as reactive, chemo- or stereo-selective reagents or catalysts.

Prof. Dr. Axel Klein
Guest Editor

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Keywords

  • luminescent complexes and materials
  • supramolecular chemistry; cytotoxicity
  • CVD
  • cyclometalation
  • structural and mechanistic studies
  • reactive species in organometallic catalysis

Published Papers (8 papers)

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Editorial

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430 KiB  
Editorial
Stayin’ Alive—Organoplatinum Complexes
by Axel Klein
Inorganics 2015, 3(2), 155-159; https://doi.org/10.3390/inorganics3020155 - 19 May 2015
Cited by 4 | Viewed by 4277
Abstract
Starting very early, with the findings of Zeise, or Pope and Peachey, organoplatinum complexes were studied intensely in the 1970s and 1980s and were found to be quite stable and very versatile. From then on, the number of publications on organoplatinum complexes has [...] Read more.
Starting very early, with the findings of Zeise, or Pope and Peachey, organoplatinum complexes were studied intensely in the 1970s and 1980s and were found to be quite stable and very versatile. From then on, the number of publications on organoplatinum complexes has more than doubled in each subsequent decade, and organoplatinum complexes have stretched into many fields of application today. This introduction to the Special Issue on “Organoplatinum Complexes” spans from the history of organoplatinum complexes to the seven manuscripts published in the frame of this Special Issue, representing some of these fields. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)

Research

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4740 KiB  
Article
Five Coordinate Platinum(II) in [Pt(bpy)(cod)(Me)][SbF6]: A Structural and Spectroscopic Study
by Axel Klein, Michael Neugebauer, Alexander Krest, Anna Lüning, Simon Garbe, Natalia Arefyeva and Nils Schlörer
Inorganics 2015, 3(2), 118-138; https://doi.org/10.3390/inorganics3020118 - 13 May 2015
Cited by 11 | Viewed by 9579
Abstract
The five coordinate organoplatinum complex [Pt(bpy)(cod)(Me)][SbF6] (cod = 1,5-cyclooctadiene, bpy = 2,2’-bipyridine) was obtained reacting [Pt(cod)(Me)Cl] with Ag[SbF6] and bpy and characterized by multiple spectroscopy (IR and NMR) and single crystal XRD. Although the application of the τ values [...] Read more.
The five coordinate organoplatinum complex [Pt(bpy)(cod)(Me)][SbF6] (cod = 1,5-cyclooctadiene, bpy = 2,2’-bipyridine) was obtained reacting [Pt(cod)(Me)Cl] with Ag[SbF6] and bpy and characterized by multiple spectroscopy (IR and NMR) and single crystal XRD. Although the application of the τ values for the discrimination between trigonal bipyramidal vs. square pyramidal coordination fails, the molecular structure can be unequivocally described as basally-distorted trigonal bipyramidal. Detailed multinuclear NMR spectroscopy in solution at ambient temperature gives strong evidence for the same structure; corresponding low-temperature measurements down to −70 °C revealed no marked dynamic processes. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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2232 KiB  
Article
Turning-On of Coumarin Phosphorescence in Acetylacetonato Platinum Complexes of Cyclometalated Pyridyl-Substituted Coumarins
by Andrej Jackel, Michael Linseis, Christian Häge and Rainer F. Winter
Inorganics 2015, 3(2), 55-81; https://doi.org/10.3390/inorganics3020055 - 17 Apr 2015
Cited by 12 | Viewed by 7160
Abstract
Two pyridine-functionalized coumarins differing with respect to the site of pyridine attachment to the coumarin dye (3 in L1 or 7 in L2) and with respect to the presence (L1) or absence (L2) of a peripheral NMe2 [...] Read more.
Two pyridine-functionalized coumarins differing with respect to the site of pyridine attachment to the coumarin dye (3 in L1 or 7 in L2) and with respect to the presence (L1) or absence (L2) of a peripheral NMe2 donor were prepared and used as cyclometalating ligands towards the Pt(acac) fragment. X-ray crystal structures of complexes 1 and 2 show strong intermolecular interactions by π-stacking and short Pt∙∙∙Pt or C-H∙∙∙O hydrogen bonding that result in the formation of sheetlike packing patterns. The NMe2 donor substituent has a profound influence on the absorption and emission properties of the free coumarin dyes; L1 emits strongly while L2 is only weakly emissive. On binding to Pt(acac) the strong fluorescence of L1 is partially quenched while coumarin phosphorescence is observed from cyclometalated L1 and L2. The ligand-centered nature of the LUMO was confirmed by IR spectroelectrochemistry while the assignment of the phosphorescence emission as ligand-based rests on the vibrational structuring, the negligible solvatochromism, the small temperature-induced Stokes shifts on cooling to 77 K, the emission lifetimes, and strong oxygen quenching. (TD-)DFT calculations confirm our experimental results and provide an assignment of the electronic transitions and the spin density distributions in the T1 state. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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1506 KiB  
Article
Experimental and Theoretical Studies of the Factors Affecting the Cycloplatination of the Chiral Ferrocenylaldimine (SC)-[(η5-C5H5)Fe{(η5-C5H4)–C(H)=N–CH(Me)(C6H5)}]
by Concepción López, Ramón Bosque, Marta Pujol, Jonathan Simó, Eila Sevilla, Mercè Font-Bardía, Ramon Messeguer and Carme Calvis
Inorganics 2014, 2(4), 620-648; https://doi.org/10.3390/inorganics2040620 - 06 Nov 2014
Cited by 10 | Viewed by 6727
Abstract
The study of the reactivity of the enantiopure ferrocenyl Schiff base (SC)-[FcCH=N–CH(Me)(C6H5)] (1) (Fc = (η5-C5H5)Fe(η5-C5H4)) with cis-[PtCl2(dmso)2 [...] Read more.
The study of the reactivity of the enantiopure ferrocenyl Schiff base (SC)-[FcCH=N–CH(Me)(C6H5)] (1) (Fc = (η5-C5H5)Fe(η5-C5H4)) with cis-[PtCl2(dmso)2] under different experimental conditions is reported. Four different types of chiral Pt(II) have been isolated and characterized. One of them is the enantiomerically pure trans-(SC)-[Pt{κ1-N[FcCH=N–CH(Me)(C6H5)]}Cl2(dmso)] (2a) in which the imine acts as a neutral N-donor ligand; while the other three are the cycloplatinated complexes: [Pt{κ2-C,N [(C6H4)–N=CHFc]}Cl(dmso)] (7a) and the two diastereomers {(Sp,SC) and (Rp,SC)} of [Pt{κ2-C,N[(η5-C5H3)–CH=N–{CH(Me)(C6H5)}]Fe(η5-C5H5)}Cl(dmso)] (8a and 9a, respectively). Isomers 7a-9a, differ in the nature of the metallated carbon atom [CPh (in 7a) or CFc (in 8a and 9a)] or the planar chirality of the 1,2-disubstituted ferrocenyl unit (8a and 9a). Reactions of 7a9a with PPh3 gave [Pt{κ2-C,N[(C6H4)–N=CHFc]}Cl(PPh3)] (in 7b) and the diastereomers (Sp,SC) and (Rp,SC) of [Pt{κ2-C,N[(η5-C5H3)–CH=N–{CH(Me)(C6H5)}] Fe(η5-C5H5)}Cl(PPh3)] (8b and 9b, respectively). Comparative studies of the electrochemical properties and cytotoxic activities on MCF7 and MDA-MB231 breast cancer cell lines of 2a and cycloplatinated complexes 7b-9b are also reported. Theoretical studies based on DFT calculations have also been carried out in order to rationalize the results obtained from the cycloplatination of 1, the stability of the Pt(II) complexes and their electrochemical properties. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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2103 KiB  
Article
A Hydrido η1-Alkynyl Diplatinum Complex Obtained from a Phosphinito Phosphanido Complex and Trimethylsilylacetylene
by Mario Latronico, Vito Gallo, Elena Lalinde, Santiago Ruiz, Stefano Todisco and Piero Mastrorilli
Inorganics 2014, 2(4), 591-605; https://doi.org/10.3390/inorganics2040591 - 31 Oct 2014
Cited by 6 | Viewed by 5095
Abstract
The reaction of (trimethylsilyl)acetylene with the phosphinito phosphanido Pt(I) complex [(PHCy2)Pt(μ-PCy2){κ2P,O-μ-P(O)Cy2}Pt(PHCy2)](Pt-Pt) (1) results in the protonation of the Pt-Pt bond with the formation of the bridging [...] Read more.
The reaction of (trimethylsilyl)acetylene with the phosphinito phosphanido Pt(I) complex [(PHCy2)Pt(μ-PCy2){κ2P,O-μ-P(O)Cy2}Pt(PHCy2)](Pt-Pt) (1) results in the protonation of the Pt-Pt bond with the formation of the bridging hydride complex [(PHCy2)(Me3SiC≡C)Pt(μ-PCy2)(μ-H) Pt(PHCy2){κP-P(O)Cy2}](Pt-Pt) (2), which was characterized by spectroscopic, spectrometric and XRD analyses. Complex 2 exhibits in the solid state at 77 K a long-lived, weak, orange emission assigned as metal-metal to ligand charge transfer (MMLCT) (L = alkynyl) due to the presence of a very short Pt···Pt distance [2.8209(2) Å]. Reaction of 2 with etherate HBF4 results in the selective protonation of the phosphinito ligand to afford the species [(PHCy2)(Me3SiC≡C)Pt(μ-PCy2)(μ-H) Pt(PHCy2){κP-P(OH)Cy2}](Pt-Pt)[BF4] ([3]BF4). Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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1849 KiB  
Article
Attachment of Luminescent Neutral “Pt(pq)(C≡CtBu)” Units to Di and Tri N-Donor Connecting Ligands: Solution Behavior and Photophysical Properties
by Elena Lalinde, M. Teresa Moreno, Santiago Ruiz and Sergio Sánchez
Inorganics 2014, 2(4), 565-590; https://doi.org/10.3390/inorganics2040565 - 31 Oct 2014
Cited by 1 | Viewed by 5621
Abstract
Binuclear derivatives [{Pt(pq)(C≡CtBu)}2(μ-L)] (1a5a), containing a series of dinitrogen linker ligands and the trinuclear [{Pt(pq)(C≡CtBu)}3(μ-L)] (6a) [L = μ-1,3,5-tris(pyridine-4-ylethynyl)benzene], formed by bridge-splitting reactions with [Pt(pq)(μ-κCα2 [...] Read more.
Binuclear derivatives [{Pt(pq)(C≡CtBu)}2(μ-L)] (1a5a), containing a series of dinitrogen linker ligands and the trinuclear [{Pt(pq)(C≡CtBu)}3(μ-L)] (6a) [L = μ-1,3,5-tris(pyridine-4-ylethynyl)benzene], formed by bridge-splitting reactions with [Pt(pq)(μ-κCα2-C≡CtBu)]2 (Pt-1), are reported. The complexes are characterized by a combination of 1H NMR spectroscopy, mass spectrometry and X-ray crystallography (2a and 4a). 1H NMR proves the existence of a dynamic equilibrium in solution between the diplatinum complexes (species a), the corresponding mononuclear complex with terminal N-donor ligands (species b), the starting material (Pt-1) and the free ligand (L). The effects of concentration, temperature and solvent properties on the equilibrium have been studied. The optical properties of these systems have been investigated by UV-visible absorption and emission spectroscopies in solid state and in solution, and the nature of the transitions and the excited state analyzed by theoretical calculations on 2a. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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1096 KiB  
Article
Half-Lantern Pt(II) and Pt(III) Complexes. New Cyclometalated Platinum Derivatives
by Violeta Sicilia, Pilar Borja and Antonio Martín
Inorganics 2014, 2(3), 508-523; https://doi.org/10.3390/inorganics2030508 - 26 Aug 2014
Cited by 12 | Viewed by 6337
Abstract
The divalent complex [{Pt(bzq)(μ-L)}2] (1) [Hbzq = benzo[h]quinolone, HL = CF3C4H2N2SH: 4-(trifluoromethyl)pyrimidine-2-thiol] was obtained from equimolar amounts of [Pt(bzq)(NCMe)2]ClO4 and 4-(trifluoromethyl)pyrimidine-2-thiol with an excess of [...] Read more.
The divalent complex [{Pt(bzq)(μ-L)}2] (1) [Hbzq = benzo[h]quinolone, HL = CF3C4H2N2SH: 4-(trifluoromethyl)pyrimidine-2-thiol] was obtained from equimolar amounts of [Pt(bzq)(NCMe)2]ClO4 and 4-(trifluoromethyl)pyrimidine-2-thiol with an excess of NEt3. The presence of a low intensity absorption band at 486 nm (CH2Cl2), assignable to a metal-metal-to-ligand charge transfer transition (1MMLCT) [dσ*(Pt)2→π*(bzq)], is indicative of the existence of two platinum centers located in close proximity because the rigidity of the half-lantern structure allows the preservation of these interactions in solution. Compound 1 undergoes two-electron oxidation upon treatment with halogens X2 (X2: Cl2, Br2 or I2) to give the corresponding dihalodiplatinum (III) complexes [{Pt(bzq)(μ-L)X}2] (L = CF3C4H2N2S-κN,S; X: Cl 2, Br 3, I 4). Complexes 24 were also obtained by reaction of 1 with HX (molar ratio 1:2, 10% excess of HX) in THF with yields of about 80% and compound 2 was also obtained by reaction of [{Pt(bzq)(μ-Cl)}2] with HL (4-(trifluoromethyl)pyrimidine-2-thiol) in molar ratio 1:2 in THF, although in small yield. The X-ray structures of 2 and 3 confirmed the half-lantern structure and the anti configuration of the molecules. Both of them show Pt–Pt distances (2.61188(15) Å 2, 2.61767(16) Å 3) in the low range of those observed in Pt2(III,III)X2 half-lantern complexes. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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Review

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631 KiB  
Review
Diarylplatinum(II) Compounds as Versatile Metallating Agents in the Synthesis of Cyclometallated Platinum Compounds with N-Donor Ligands
by Margarita Crespo
Inorganics 2014, 2(1), 115-131; https://doi.org/10.3390/inorganics2010115 - 21 Mar 2014
Cited by 15 | Viewed by 8426
Abstract
This review deals with the reactions of diarylplatinum(II) complexes with N-donor ligands to produce a variety of cycloplatinated compounds including endo-five-, endo-seven-, endo-six- or exo-five-membered platinacycles. The observed reactions result from a series of oxidative addition/reductive elimination processes [...] Read more.
This review deals with the reactions of diarylplatinum(II) complexes with N-donor ligands to produce a variety of cycloplatinated compounds including endo-five-, endo-seven-, endo-six- or exo-five-membered platinacycles. The observed reactions result from a series of oxidative addition/reductive elimination processes taking place at platinum(II)/platinum(IV) species and involving C–X (X = H, Cl, Br) bond activation, arene elimination, and, in some cases, Caryl–Caryl bond formation. Full article
(This article belongs to the Special Issue Organoplatinum Complexes)
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