- In Vitro Anticancer Activity of Nanoformulated Mono- and Di-nuclear Pt Compounds
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Nanoformulations of mononuclear Pt complexes cis-PtCl2(PPh3)2 (1), [Pt(PPh3)2(L?Cys)] ? H2O (3, L?Cys=L-cysteinate), trans-PtCl2(PPh2PhNMe2)2 (4;
- Wang, Pan,Wang, Jian-Wei,Zhang, Wen-Hua,Bai, Hongzhen,Tang, Guping,Young, David J.
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p. 2993 - 3000
(2021/08/23)
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- The coordination chemistry of sulfonyl-substituted thioureas towards the d8 metal centres platinum(II), palladium(II), nickel(II) and gold(III)
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Reactions of the complexes cis-[PtCl2(PPh3)2], [PtCl2(dppp)] (dppp = Ph2P(CH2)3PPh2), [MCl2(dppe)] (dppe = Ph2P(CH2)2PPh2, M = Ni, Pd), [PdCl2(bipy)] (bipy = 2,2′-bipyridine) and [AuCl2(bp)] (bp = cyclometallated 2-benzylpyridine) with p-TolSO2NHC(S)NHPh and Et3N in refluxing methanol gave a series of new thiourea complexes containing the ligand bound as a dianion through the S and the NPh groups. The related thioureas RSO2NHC(S)NHPh (R = Me, Et) and p-TolSO2NHC(S)NHCH2CH=CH2 were also reacted with cis-[PtCl2(PPh3)2] to form the corresponding complexes [Pt{RSO2NC(S)NPh}(PPh3)2] and [Pt{TolSO2NC(S)NCH2CH=CH2}(PPh3)2] respectively. X-ray structure determinations were carried out on the thiourea MeSO2NHC(S)NHPh and its platinum complex [Pt{MeSO2NC(S)NPh}(PPh3)2], as well as [Pt{TolSO2NC(S)NPh}(PPh3)2]. Both complexes form the distal isomer with a remote NSO2R group, and no evidence was observed for isomerisation of these platinum complexes in solution. The palladium complexes [Pd{TolSO2NC(S)NPh}L2] [L2 = Ph2PCH2CH2PPh2 (dppe), or 2,2′-bipyridine (bipy)] undergo decomposition in solution to form the sulfide-bridged aggregates [Pd3S2(L2)3]2+, identified by ESI MS and 31P NMR.
- Henderson, William,Risi, Matthew C.,Saunders, Graham C.
-
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- Pyrrole thioamide complexes of the d8 metals platinum(II), palladium(II) and gold(III)
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Reactions of the cycloaurated gold(III) complexes [AuCl2(2-benzylpyridyl)] and [AuCl2(C6H4CH2NMe2)] with a set of pyrrole-2-thioamide ligands, containing various substituents on the pyrrole ring, gave a series of new gold(III) pyrrole thioamide complexes. X-ray crystal structures on two complexes indicate that the pyrrole thioamide ligand is coordinated through the deprotonated pyrrole nitrogen, as well as the sulfur atom of the deprotonated thioamide group, forming five-membered chelate ring complexes. In both complexes, the two highest trans-influence donor atoms (C and S) are mutually cis. Related sets of platinum(II) and palladium(II) pyrrole thioamide complexes were similarly prepared by reactions of cis-[PtCl2(PPh3)2] and [PdCl2(dppe)] (dppe = Ph2PCH2CH2PPh2)] respectively. The complexes were characterised by NMR and IR spectroscopies, and ESI mass spectrometry. A preliminary investigation of the activity of a selection of compounds towards A549 (adenocarcinomic human alveolar basal epithelial) cells was also carried out.
- Tang, Haiming,Saunders, Graham C.,Ma, Xiaochuan,Henderson, William
-
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- Further Approaches in the Design of Antitumor Agents with Response to Cell Resistance: Looking toward Aza Crown Ether-dtc Complexes
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The dianionic aza crown ether-dtc N,N′-bis(dithiocarbamate)-1,10-diaza-18-crown-6 (L2-) is a versatile ligand capable of yielding binuclear complexes with group 10 elements, also known as Ni-triade, [μ-(κ2-S,-S′-L)M2(PPh3)4]Cl2 (M = Pd (1), Pt (2)), [μ-(κ2-S,-S′-L)M2(PPh3)4](BPh4)2 (M = Pd (3), Pt (4)), and μ-(κ-S,-S′-L)Ni2(PPh3)2Cl2 (5), and has proven to be an excellent option to the design of metal-based drugs able to provide multiple response to cell resistance. Palladium and platinum complexes, 1 and 2, were tested for cytotoxicity in the human cervix carcinoma cell line HeLa-229, the human ovarian carcinoma cell line A2780, and the cisplatin-resistant mutant A2780cis, finding significant activity toward all three cancer cell lines, with low micromolar IC50 values, comparable to cisplatin. Markedly, against the cisplatin resistant cell line A2780cis, compound 2 exhibits better cytotoxic activity than the clinical drug (IC50 = 2.3 ± 0.2 μM for 2 versus 3.6 ± 0.5 μM for cisplatin). Moreover, an enhancement of the antitumor response is achieved when adding an equimolar amount of alkali metal chloride (NaCl or KCl) to the medium, for instance, testing compound 1 against the cisplatin-resistant A2780cis cells, the IC50 decreases from 9.3 ± 0.4 to 7.4 ± 0.3 and 5.4 ± 0.1 μM, respectively, after addition of the salt solution. For the platinum derivative 2, the IC50 improves by ca. 40% reaching 1.3 ± 0.1 μM when potassium chloride is added. Likewise, the resistant factor found for 2 (RF = 1) confirms that this complex circumvents cisplatin-resistance in A2780cis and is improved with the addition of potassium chloride (RF = 0.65). The presence of the aza crown ether moiety as linker in the systems studied herein is a key point since, in addition to allowing and facilitating interaction with alkali metal ions, this unit is flexible enough to adapt to a variety of environments, as confirmed by the X-ray crystal structures described, where different conformations and ways to fold in are found. In order to gain insight into the electronic and structural facts involved in the interaction of complex 2 with the alkali metal ions, a DFT study was performed, and the description of the molecular electrostatic potentials (MEPs) is also presented.
- Arenaza-Corona, Antonino,Barba, Victor,Couce-Fortúnez, M. Delfina,De Blas, Andrés,H?pfl, Herbert,Morales-Morales, David,Rodríguez-Blas, Teresa,Santillan, Rosa
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p. 15120 - 15134
(2020/11/02)
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- From NHC to Imidazolyl Ligand: Synthesis of Platinum and Palladium Complexes d10-[M(NHC)2] (M = Pd, Pt) of the NHC 1,3-Diisopropylimidazolin-2-ylidene
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The widely held belief that N-heterocyclic carbenes (NHCs) act only as innocent spectator ligands is not always accurate, even in the context of well-explored reactions. Ligand exchange in the conversion of [Pt(PPh3)2(I2-C2H4)] (3) to [Pt(iPr2Im)2] (2) depends critically on the particular reaction conditions employed, with slight changes leading to vastly different outcomes. In addition to [Pt(iPr2Im)2] (2), complexes [Pt(iPr2Im)(PPh3)(I2-C2H4)] (5) and trans-[Pt(iPr2Im)2(iPr-Im)(H)] (6) were isolated and in the case of 6 fully characterized. Complex 5 represents the first mixed-olefin complex in transition metal chemistry containing both an NHC and a phosphine ligand. Chemical degradation of the NHC was shown to yield the new imidazole-2-yl iPr-Im? in 6. Therefore, the synthesis of [Pt(iPr2Im)2] (2) via metallic reduction of the ionic precursor [Pt(iPr2Im)3(Cl)]+Cl- (9) is favorable, a procedure adaptable to analogous palladium compounds. While [Pd(iPr2Im)3(Cl)]+Cl- (8) is the only product obtained from the reaction of iPr2Im and PdCl2, neutral [Pt(iPr2Im)2(Cl)2] (10), formed as a mixture of its two stereoisomers cis-10 and trans-10, is available through precise control of the stoichiometry in the reaction of PtCl2 and exactly 2 equiv of iPr2Im.
- Hering, Florian,Radius, Udo
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p. 3236 - 3245
(2016/01/15)
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- Trans-cis isomerization of [(C6H5)3P]2PtCl2 complex in dimethylformamide solutions
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The kinetics of the trans-cis isomerization reactions of the [(C6H5)3P]2PtCl2 neutral complex catalyzed by four different metal ions: Be2+, Mg2+, Ca2+ and Sr2+ has been studied. The isomerization reactions were investigated in dimethylformamide (DMF) solutions at five temperatures in the range of 278-298 K keeping a constant concentration of metal ions c = 0.5 M. The rates of the isomerization reactions were determined spectrophotometrically by monitoring the absorbance changes at the 277 nm wavelength. The spectral measurements were carried out in the UV-Vis region using the Perkin-Elmer Lambda 650 instrument with the scan accuracy of 1 nm and 1 nm slit width at the 120 scanning rate. The observable rate constants were computed using the Glint program based on the global analysis. The activation energies were determined using the Arrhenius equation. The differences in the structures of the obtained cis and trans geometric isomers were confirmed on the basis of their IR spectra.
- Jacewicz, Dagmara,Pranczk, Joanna,Wyrzykowski, Dariusz,?amoj?, Krzysztof,Chmurzyński, Lech
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p. 620 - 624
(2015/02/19)
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- An investigation of the mixed-bridge dinuclear complex [Pt 2(μ-S)(μ-NH2)(PPh3)4] +
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The product formed by reaction of cis-[PtCl2(PPh 3)2], NH3 and Na2S in ethanol, previously reported as [Pt2(μ-S)(PPh3)4], has been reinvestigated by electrospray ionisation mass spectrometry (ESI MS) and found to consist of the ethanol solvate of the well-known metalloligand [Pt2(μ-S)2(PPh3)4] together with the novel mixed-ligand complex [Pt2(μ-S)(μ-NH 2)(PPh3)4]+. Upon prolonged ageing in air, a mixture of this complex with [Pt2(μ-S)(μ-O)(PPh 3)4 + H]+ is observed by ESI MS. [Pt 2(μ-S)(μ-NH2)(PPh3)4] + can be prepared from cis-[PtCl2(PPh3) 2] and aqueous NH3 using a stoichiometric quantity of sodium sulfide, or by reaction of [Pt2(μ-S)2(PPh 3)4] with 2-chloro-1-methylpyridinium tetraphenylborate and ammonia; the complex was structurally characterised as its tetraphenylborate salt. This novel desulfurisation reaction was serendipitously discovered during investigations on the reactivity of [Pt2(μ-S) 2(PPh3)4] towards 2-chloro-1-methylpyridinium iodide giving the known iodo complex [Pt2(μ-S)(μ-I)(PPh 3)4]+, isolated as either the PF 6- or I- salts.
- Henderson, William,Oliver, Allen G.
-
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- Isomerization of platinum-coordinated iminoethers induced by spectator ligands: Stabilization of the Z anti configuration
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Iminoether derivatives of the formula trans-[PtCl2{HN=C(R) OR′}2] proved to be endowed with remarkable antitumor activity in vivo. Moreover, these trans compounds were more cytotoxic than their cis congeners, a trend opposite to that generally observed for corresponding platinum complexes with ammines. The imino ligands can have either E or Z configuration about the C=N double bond, and in the case of R = R′ = Me, the E configuration is by far thermodynamically preferred. However, substitution of chloride anions with neutral ligands (L) alters the relative stability of the E and Z isomers. Upon investigation of the derivatives with L = PPh 3, AsPh3, Me2S=O, and (H2N) 2C=S, it has been concluded that an electrostatic interaction between the oxygen lone pair of the iminoether and the platinum center, fostered by the net positive charge of the complex and the low dielectric constant around the metal core provided by the hydrophobic L ligands, stabilizes the Z configuration. The same factors can favor iminoether isomerization. These conclusions are fully supported by X-ray crystal data. In the case of a reaction with thiourea, an aminic group of thiourea can substitute the methoxy group of a cis-iminoether, leading to the formation of a cyclic compound in a process reminiscent of the McLafferty rearrangement. Such a rearrangement could play a role in the interaction of the platinum-iminoether compounds with target DNA and proteins.
- Giardina-Papa, Daniela,Intini, Francesco P.,Pacifico, Concetta,Natile, Giovanni
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p. 13058 - 13067
(2013/12/04)
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- Diplatinum complexes: Chemoselective reactions of the μ-orthometalated, metal-metal bonded complex
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In order to investigate further the chemoselectivity of reactions involving the μ-orthometalated, metal-metal bonded dinuclear Pt(I) complex [Pt 2(μ-o-C6H4PPh2)(μ-PPh 2)(PPh3)2](Pt-Pt) (1), it was reacted with HCl and HI using various stoichiometries. The first step was the breaking of the metal-carbon bond and the formation of C-H and Pt-X bonds. When a 1:1 ratio was used, the complexes [Pt2X(μ-PPh2)(PPh3) 3](Pt-Pt) (2, X = Cl; 3, X = I) have been obtained but the use of a 2:1 ratio resulted instead in the formation of the complexes [Pt 2(μ-H)(μ-PPh2)X2(PPh3) 2](Pt-Pt) (4, X = Cl; 6, X = I). The latter transformed into [Pt 2(μ-X)(μ-PPh2)X2(PPh3) 2] (5, X = Cl; 7, X = I) in the presence of an additional equivalent of HX. The cis,cis- and cis,trans-isomers of 7 were also obtained by oxidation of 3 with one equivalent of iodine. Whereas compounds 4, cis,cis-5, and cis,trans-7 have been characterized in solution, the complexes 2·1/2C7H8, 3, 6 and cis,cis-7 have been isolated and structurally characterized by X-ray diffraction.
- Archambault, Christine,Bender, Robert,Dusausoy, Yves,Welter, Richard,Braunstein, Pierre
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p. 545 - 552
(2013/06/26)
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- Diverse C-C bond-forming reactions of bis(carbene)platinum(II) complexes
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The platinum(0) complex Pt(PPh3)4 catalyzes coupling of the carbene ligands of (CO)5Cr{C(OMe)(p-MeOC6H 4)} (1). The stable bis(carbene)platinum(II) complexes Cl 2Pt{C(OMe)(Me)}2
- Klet, Rachel C.,Labinger, Jay A.,Bercaw, John E.
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p. 6652 - 6657
(2012/11/07)
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- A convenient route to dinuclear chloro-bridged platinum(II) derivatives via nitrile complexes
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The syntheses of the complexes [PtCl2(NCR)L] [R = Me, Et; L = PPh3; R = Et, L = Py, CO] and [PtCl{(κ2-P,C) P(OC6H4)(OPh)2}(NCEt)] are described starting from the easily available [PtCl2(NCR)2]. The stability of the products under different experimental conditions is discussed as well as their use as precursors to dinuclear complexes [Pt(μ-Cl)ClL]2. The crystal and molecular structures of cis-[PtCl2(NCEt)(PPh 3)], [SP-4-2]-[PtCl{(κ2-P,C)P(OC6H 4)(OPh)2}(NCEt)] and trans-[Pt(μ-Cl) {(κ2-P,C)P(OC6H4)(OPh)2}] 2 are reported.
- Dell'Amico, Daniela Belli,Labella, Luca,Marchetti, Fabio,Samaritani, Simona
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p. 1389 - 1396
(2012/03/07)
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- Metal-promoted synthesis of amidines containing the model nucleobases 1-methylcytosine and 9-methyladenine
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The amidine complexes cis-[L2PtNHC(R){1-MeCy(-2H)}]NO 3 (R = Me, 1a; Ph, 1b, Me3C, 1c; Ph2(H)C, 1d) and cis-[L2PtNHC(R){9-MeAd(-2H)}]NO3 (R = Me, 2a; Ph, 2b; Me3C, 2c; Ph2(H)C, 2d), are formed when cis-[L 2Pt(μ-OH)]2(NO3)2 (L = PPh 3) reacts with 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) in solution of MeCN, PhCN, Me3CCN and Ph2(H)CCN. Reaction of 1a,b and 2a,b with HCl affords the protonated amidines [NH 2C(R){1-MeCy(-H)}]NO3 (R = Me, 3a; Ph, 3b) and [NH 2C(R){9-MeAd(-H)}]NO3 (R = Me, 4a; Ph, 4b) and cis-(PPh3)2PtCl2 in quantitative yield. Treatment of 3b and 4b with NaOH allows the isolation of the neutral benzimidamides NH2-C(Ph){1-MeCy(-2H)} (5b) and NH2-C(Ph) {9-MeAd(-2H)} (6b). In the solid state 3b shows a planar structure with the hydrogen atom on N(4) cytosine position involved in a strong H-bond with the NO3- ion. Intermolecular H-bonds between the oxygen of the cytosine ring and one of the H atoms of the amidine-NH2 group allow the dimerization of the molecule. A detailed analysis of the spectra of 3b in DMF-d7 at -55 °C indicates the presence of an equilibrium between the species [NH2C(R){1-MeCy(-H)}]NO3 and [NH 2C(R){1-MeCy(-H)}]2(NO3)2, exchanging with trace amounts of water at 25 °C. [15N, 1H]-HMBC experiments for 5b and 6b indicate that the amino tautomer H2N-C(Ph){nucleobase(-2H)}, is the only detectable in solution and such structure has been confirmed in the solid state. The reaction of 5b and 6b with cis-L2Pt(ONO2)2 (L = PPh3), in chlorinated solvents, determines the immediate appearance of a pale yellow colour due to the coordination of the neutral amidine, likely in its imino form HNC(Ph){nucleobase(-H)}, to give the adducts cis-[L2PtNHC(Ph) {nucleobase(-H)}]2+. In fact, addition of "proton sponge" leads to the immediate deprotonation of the amidine ligand with formation of the starting complexes 1b and 2b. The Royal Society of Chemistry 2011.
- Montagner, Diego,Zangrando, Ennio,Borsato, Giuseppe,Lucchini, Vittorio,Longato, Bruno
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p. 8664 - 8674
(2011/10/10)
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- Coulombic inter-ligand repulsion effects on the Pt(ii) coordination chemistry of oligocationic, ammonium-functionalized triarylphosphines
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The Pt(ii) coordination chemistry of oligocationic ammoniomethyl- and neutral aminomethyl-substituted triarylphosphines (L) is described. Complexes of the type PtX2(L)2 (X = Cl, I) have been isolated and characterized. For the hexa-meta-ammoniomethyl-substituted ligands [1] 6+ and [2]6+, two ligands always occupy a trans-configuration with respect to each other in complexes of the type PtX 2(L)2, while for the tri-para-ammoniomethyl-substituted ligand [7]3+, the trans/cis ratio is dependent on the ionic strength of the solution. This behaviour was not observed for the neutral aminomethyl-substituted ligands. In the crystal structure of trans-[PtI 2(1)2]I12, the geometrical parameters of the phosphine ligand [1]6+ are very similar to those found in the analogous complex of the benchmark ligand PPh3, i.e. trans-PtI 2(PPh3)2, indicating that no significant increase in the steric congestion is present in the complex. Instead, the coordination chemistry of this class of phosphine ligands is dominated by repulsive Coulombic inter-ligand interactions.
- Snelders, Dennis J. M.,Siegler, Maxime A.,Von Chrzanowski, Lars S.,Spek, Anthony L.,Van Koten, Gerard,Gebbink, Robertus J. M. Klein
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p. 2588 - 2600
(2011/05/04)
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- The microwave synthesis of platinum(II) phosphine complexes
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The microwave synthesis of a series of platinum(II) phosphine complexes is reported. The complexes dppePtCl2 (dppe = bis(diphenylphosphino) ethane), dpppPtCl2 (dppp = bis(diphenylphosphino)propane), dppmPtCl2 (dppm = bis(diphenylphosphino)methane) and cis-(Ph 3P)2PtCl2 are synthesized from the reaction of potassium tetrachloroplatinate(II) and the phosphine. The isolated yields are 65% or better.
- Dopke, Nancy Carter,Oemke, Holly E.
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p. 638 - 640
(2011/10/30)
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- Synthesis and reaction chemistry of heterodi- and heterotrimetallic transition-metal complexes based on 1-(Diphenylphosphanyl)-1'- terpyridylferrocene
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The reaction of [Fe(η5-C5H4PPh 2)(η5-C5H4terpy)] (5; terpy = 2,2':6',2''-terpyridin-4'-yl) with diverse transition-metal compounds including [PtCl2(Et2S)2], [Pd(cod)X2], [AuCl(tht)], [CuBr], [Mo(CO)4(nbd)], and [{RhCl(cod)}2] (X = Cl, Br; tht = tetrahydrothiophene; nbd = norbornadiene; cod = cyclooctadiene) to afford heterobi- and trimetallic complexes and a coordination polymer is reported. The following compounds were prepared: [Fe(η5-C 5H4PPh2{PtCl2(SEt 2)})(η5-C5H4terpy)] (7), trans-[PtCl2{(Ph2P-η5-C5H 4)(η5-C5H4terpy)-Fe} 2] (9), [Fe(η5-C5H4PPh 2PdCl2)(η5-C5H 4terpy)] (12), [Fe{η5-C5H 4PPh2(Cl3Pd-)}(η5-C 5H4terpy{(dmso)2ClNi+})] (14), trans-[PdX2{(Ph2P-η5-C5H 4)(η5-C5H4terpy)Fe} 2] (16a, X = Cl; 16b, X = Br), [Mo(CO)4{(η 5-C5H4PPh2)(η5-C 5H4terpy)Fe}2] (17), [Fe{η5- C5H4Ph2P(CuBr)}(η5-C 5H4terpy)]n (19), [Fe{η5-C 5H4Ph2P(AuCl)}(η5-C 5H4terpy)] (22), [Fe(η5-C5H 4Ph2P-{Rh(cod)Cl})(η5-C5H 4terpy)] (23), [Ru({η5-C5H 4Ph2P(AuCl)}-(η5-C5H 4terpy)Fe)2]Cl2 (25), and [Fe{η5-C 5H4PPh2-(PdCl2)}{η5- C5H4-CH=CHC(O)(py)}] (26). The molecular structures of 5, 9, 12, 14, 16b, 22, and 26 in the solid state are reported. They show typical features of related phosphanylferrocenes and terpyridylferrocenes. Characteristic of 12 is a C-H activation as a result of the close distance of palladium to the terpyridyl moiety. Complexes 12, 26, and [PdCl2(dppf)] [dppf = 1,1'-bis(diphenylphosphanyl)ferrocene], for comparison, were used in preliminary studies as catalysts in the carbon-carbon coupling of iodobenzene with tert-butyl acrylate to give (E)-tert-butyl cinnamate. The conversion amounts to 80% with a turnover number of 160 and turnover frequency of 48 h-1.
- Hildebrandt, Alexander,Wetzold, Nora,Ecorchard, Petra,Walfort, Bernhard,Rueffer, Tobias,Lang, Heinrich
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p. 3615 - 3627
(2011/01/07)
-
- Cooperation between cis and trans influences in cis-Pt II(PPh3)2 complexes: Structural, spectroscopic, and computational studies
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The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX2(PPh3)2] and cis-[PtXY(PPh 3)2] complexes have been studied by the X-ray crystal structures of several derivatives (X2 = (AcO)2 (3), (NO3)2 (5), Br2 (7), I2 (11); and XY = Cl(AcO) (2), Cl(NO3) (4), and Cl(NO2) (13)), density functional theory (DFT) calculations, and one bond Pt-P coupling constants, JPtp. The latter have allowed an evaluation of the relative magnitude of both influences. It is concluded that such influences act in a cooperative way and that the cis influence is not irrelevant when rationalizing the 1 JPtp values, as well as the experimental Pt-P bond distances. On the contrary, in the optimized geometries, evaluated through B3LYP/def2-SVP calculations, the cis influence was not observed, except for compounds CIPh (21), Ph2 (22), and, to a lesser extent, Cl(NO2) (13) and (NO2) 2(14). A natural bond order analysis on the optimized structures, however, has shown how the cis influence can be related to the s-character of the Pt hybrid orbital involved in the Pt-P bonds and the net atomic charge on Pt. We have also found that in the X-ray structures of cis-[PtX 2(PPh3)2] complexes the two Pt-X and the two Pt-P bond lengths are different each other and are related to the conformation of the phosphine groups, rather than to the crystal packing, since this feature is observed also in the optimized geometries.
- Rigamonti, Luca,Forni, Alessandra,Manassero, Mario,Manassero, Carlo,Pasini, Alessandro
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p. 123 - 135
(2010/03/04)
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- Novel reactivity aspects of cis-bis(1-alkenyl)platinum(II) compounds of the type Pt(CH2(CH2)nCHCH2) 2L2 (where L2 = dppp, dppe, dppm and n = 1, 2)
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We describe the synthesis, structure and reactivity of novel bis(1-alkenyl)platinum(II) complexes, Pt[CH2(CH2) nCHCH2]2L2 (where L2 = dppp, dppe, dppm and n = 1, 2). The stability of the title complexes with the different ligands is discussed. The steric, chelating and electronic properties of the ligands have a significant impact on the structure as well as on the reactivity of the complexes. Novel reactions with elemental sulfur and carbon dioxide are described and discussed.
- Sivaramakrishna, Akella,Moss, John R.,Su, Hong
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p. 3345 - 3350
(2011/02/16)
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- Platinum(II)-promoted [2+3] cycloaddition of azide with 4-cyanobenzaldehyde, a schiff base derivative or dicyanobenzenes to give formyl-, amino(imino)- or cyano-functionalized tetrazolato complexes
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The [2+3] cycloaddition reaction (which is greatly accelerated by microwave irradiation) of the bis(azido)platinum(II) compound cis-[Pt(N3) 2(PPh3)2] (1) with 4-cyanobenzaldehyde (2) furnishes the N2N
- Lasri, Jamal,Guedes Da Silva,Kopylovich, Maximilian N.,Mukhopadhyay, Bhaswati Ghosh,Pombeiro, Armando J. L.
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p. 5541 - 5549
(2010/06/15)
-
- Cis Influence in trans-Pt(PPh3)2 complexes
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The cis influence of a series of anionic ligands X and Y has been evaluated through the magnitude of the Pt-P coupling constants for compounds of formula trans-[PtXY(PPh3)2]. The order of decreasing cis influence was found to be I > Cl > SePh ~ SPh ~ SEt > NO3 > AcO ~ NO2 > H > Me > Ph > mtc (mtc = N,N-dimethylmonothiocarbamato-S); moreover, the cis influences of the various ligands was found to be additive. The X-ray structures of three representative compounds (t-4: X = Cl, Y = NO3; t-5: X = Cl, Y = AcO and t-12: X = Y = NO2) have also been determined. The Royal Society of Chemistry 2009.
- Rigamonti, Luca,Manassero, Carlo,Rusconi, Michele,Manassero, Mario,Pasini, Alessandro
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p. 1206 - 1213
(2009/06/17)
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- Synthesis, structure and reactivity of cis-[PtL2(1-alkenyl)2] complexes
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The synthesis and characterization of several new bis(1-alkenyl)platinum(II) complexes have been carried out. The structure of cis-[Pt(dppp)((CH2)6CH{double bond, long}CH2)2] has been determined by X-ray crystallography. The stability and reactivity of the compounds, cis-[PtL2((CH2)nCH{double bond, long}CH2)2] (n = 3 or 4 and L2 = 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)ethane (dppe), L = PPh3) is strongly dependent on the nature of ligand systems. It is found that the insertion of carbon monoxide into the metal-carbon bonds of the platinum alkenyl complexes is possible. Other reactions including transmetalation, intermolecular alkenyl migrations, oxidative addition of methyl iodide are described and the thermal decomposition of the bis(alkenyl) complexes are also reported.
- Sivaramakrishna, Akella,Makhubela, Banothile C.E.,Zheng, Feng,Su, Hong,Smith, Gregory S.,Moss, John R.
-
-
- New coordination modes of L-ascorbic acid and dehydro-L-ascorbic acid as dianionic chelating ligand for platinum
-
A variety of coordination modes of L-ascorbic acid as an anionic bidentate ligand has been exploited to prepare platinum(II) complexes 1-7 that contain phosphanes or R,R-dach (1R,2R-diaminocyclohexane) as neutral ligands in which O2, O3, O5, O6 and C2 act as anionic donating functionalities. An alternative synthetic route to known O2,O3 complexes is proposed, and their solubility in water has been enhanced by introducing PTA (1,3,5-triaza-7-phosphaadamantane) as a neutral ligand. A new coordination mode of ascorbic acid (O2 and O3 protected) as an O5,O6-diolate chelating ligand has been characterised in solution by NMR spectroscopy and in the solid state by X-ray crystallography. The first example of a platinum complex that contains dehydroascorbic acid, 7, has also been prepared and its X-ray crystal structure has been determined. The antiproliferative activity in vitro of complexes 1-7 has been tested, and the best values were obtained for the DHA complex 7, which was found to be more active than cisplatin on both a cisplatin-sensitive and a cisplatin-resistant cell line. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Bergamini, Paola,Marchesi, Elena,Bertolasi, Valerio,Fogagnolo, Marco,Scarpantonio, Luca,Manfredini, Stefano,Vertuani, Silvia,Canella, Alessandro
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p. 529 - 537
(2008/12/22)
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- The influence of substituents at C2 carbon atom of thiosemicarbazones {R(H)C2=N3-N2(H)-C 1(=S)-N1H2} on their dentacy in Pt II/PdII complexes: Synthesis, spectroscopy, and crystal structures
-
The coordination chemistry of platinum(II) with a series of thiosemicarbazones {R(H)C2=N3-N2(H)-C 1(=S)-N1H2, R = 2-hydroxyphenyl, H 2stsc; pyrrole, H2ptsc; phenyl, Hbtsc} is described. Reactions of trans-PtCl2(PPh3)2 precursor with H2stsc (or H2ptsc) in 1:1 molar ratio in the presence of Et3N base yielded complexes, [Pt(η3- O, N3, S-stsc)(PPh3)] (1) and [Pt(η3- N4, N 3, S-ptsc)(PPh3)] (2), respectively. Further, trans-PtCl2(PPh3)2 and Hbtsc in 1:2 (M:L) molar ratio yielded a different compound, [Pt(η2- N3, S-btsc)(η1-S-btsc)(PPh3)] (3). Complex 1 involved deprotonation of hydrazinic (-N2H-) and hydroxyl (-OH) groups, and stsc2- is coordinating via O, N3, S donor atoms, while complex 2 involved deprotonation of hydrazinic (-N2H-) and -N 4H groups and ptsc2- is probably coordinating via N 4, N3, S donor atoms. Reaction of PdCl 2(PPh3)2 with Hbtsc-Me {C6H 5(CH3)C2=N3-N2(H)-C 1(=S)-N1H2} yielded a cyclometallated complex [Pd(η3-C, N3, S-btsc-Me)(PPh3)] (4). These complexes have been characterized with the help of analytical data, spectroscopic techniques {IR, NMR (1H, 31P), U.V} and single crystal X-ray crystallography (1, 3 and 4). The effects of substituents at C2 carbon of thiosemicarbazones on their dentacy and cyclometallation are emphasized.
- Lobana, Tarlok S.,Bawa, Gagandeep,Hundal, Geeta,Zeller
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p. 931 - 937
(2009/04/13)
-
- Group 8 and 10 hyponitrite and dinitrosyl complexes
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cis-Hyponitrite complexes LnM(N2O2) (M = Ni, Pt; Ln = PPh3, PPh2Me, dppe, and dppf) of divalent group 10 metals have been previously shown to be readily prepared by treating the corresponding LnMCl2 derivatives with sodium-(Z)-1-{4-(2,6-di-tert-butyl-4-methoxycyclohexadienonyl)}diazen-1-ium-1,2-diolate. These complexes adopt a diamagnetic square planar geometry with oxygen bound chelating planar cis-hyponitrite ligands. They are readily prepared at room temperature but thermally decompose above 90 °C with release of nitrous oxide. Electrophiles such as iodine, methyltriflate, and hydrochloric acid also react rapidly with the cis-hyponitrite complexes to give nitrous oxide. The structure of one of these previously prepared complexes, (PPh3)2Pt(N2O2), has been redetermined at -100 °C as a dichloromethane solvate with improved precision. The related tetrahedral group 8 dinitrosyl complexes, (PPh3)2M(NO)2 (M = Ru, Os; Ln = PPh3, dppe, and dppf) have been reexamined and new derivatives with chelating phosphines have been prepared by ligand substitution on the corresponding (PPh3)2M(NO)2. The structures of Ru(dppf)(NO)2 and Os(dppe)(NO)2 have been determined. These two analogous families of cis-hyponitrite and dinitrosyl complexes illustrate the balance of metal dn electron count and nitrosyl redox state with one having linear nitrosyls bound to low valent metal centers, and the former having coupled N2 O22 - ligands bound to a higher oxidation state metal center.
- Arulsamy, Navamoney,Bohle, D. Scott,Imonigie, Jerome A.,Moore, Raecca C.
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p. 4737 - 4745
(2008/10/09)
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- Acetonyl platinum(II) complexes
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Me4N[Pt{CH2C(O)Me}Cl2(η2- C2H4)] (1), reacts either (1) with neutral ligands to afford cis-Me4N[Pt{CH2C(O)Me}Cl2(L)] (L = CO (2), η2-PhCH=CH2 (3), η2-PhC=CPh (4), η2-H2C=C=CMe2 (5), PPh3 (6), AsPh3 (7)), trans- or/and cis-[Pt{CH2C(O)Me}CIL 2] (L = PPh3 (8), AsPh3 (9), tht (10), XyNC (11), 'BuNC (12), py (17)), [Pt(CH2C(O)Me)Cl(η2-C 2H4)(L)] (L = py (16)), or cIS-[Pt{CH2C(O)Me} ClL2] (L2 = norbornadiene (nbd, 18), 1,5-cyclooctadiene (cod, 19), bis(diphenylphosphino)methane (dppm, 20), 4,4′-di-tert-butyl-2, 2′-bipyridyl (dbbpy, 21)) or (2) with [Tl(acac)] to give [Pt{CH 2C(O)Me}(O,Oacac)(η2-C2H4)] (22) which reacts with neutral ligands to give [Pt{CH2C(O)Me}(O,O-acac) (L)] (L = CO (23), PPh3 (24), XyNC (25)). The different behavior of py and stronger π-acceptor ligands, as CO and PR3 toward 1, has been explained through a DFT study. Reaction of 11trans with 2 equiv of XyNC affords a mixture of trans-[Pt(C(O)NHXy JCl(CNXy)2] (13) and irans-[Pt{C(NHXy)2}Cl(CNXy)2]Cl (14). The first was isolated by recrystallization and the latter by reacting CW-[PtCl2(CNXy)2] with 2 equiv of XyNC. However, cis-[Pt{CH2C(O)Me}2(bpy)] reacts with 4 equiv of XyNC to give cis-[Pt(CH2C(O)Me)2(CNXy) 2] (15).
- Vicente, Jose,Arcas, Aurelia,Fernandez-Hernandez, Jesus M.,Aullon, Gabriel,Bautista, Delia
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p. 6155 - 6169
(2008/10/09)
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- Supramolecular bidentate phosphorus ligands based on bis-zinc(ii) and bis-tin(iv) porphyrin building blocks
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Selective metal-ligand interactions have been used to prepare supramolecular bidentate ligands by mixing monodentate ligands with a suitable template. For these assemblies pyridine phosphorus ligands and a zinc(II) porphyrin dimer were used. In the rhodium-catalysed hydroformylation of 1-octene and styrene improved selectivities have been obtained for some of the assembled bidentate ligand systems. In the palladium catalysed asymmetric allylic alkylation similar effects were observed; the enantioselectivity increased by using a bisporphyrin template. The preparation of supramolecular catalyst systems was also explored using tin-oxygen interactions. Dihydroxotin(iv) porphyrin and carboxylic phosphorus ligands assemble into supramolecular ligands and the phosphorus donor atom coordinates to transition metals. The stronger oxygen-tin bond, compared to pyridine-zinc does not result in a better performance of the catalyst. The Royal Society of Chemistry.
- Slagt, Vincent F.,Van Leeuwen, Piet W. N. M.,Reek, Joost N. H.
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p. 2302 - 2310
(2007/10/03)
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- A comparative study of the structures and reactivity of cyclometallated platinum compounds of N-benzylidenebenzylamines and cycloplatination of a primary amine
-
The reaction of cis-[PtCl2(dmso)2] with ligands 4-ClC6H4CHNCH2C6H5 (1a) and 4-ClC6H4CHNCH2(4-ClC6H 4) (1b) in the presence of sodium acetate and using either methanol or toluene as solvent produced the corresponding five-membered endo-metallacycles [PtCl{(4-ClC6H3)CHNCH2C 6H5}{SOMe2}] (2a) and [PtCl{(4-ClC 6H3)CHNCH2(4′-ClC6H 4)}{SOMe2}] (2b). An analogous reaction for ligands 2,6-Cl2C6H3CHNCH2C6H 5 (1c) and 2,6-Cl2C6H3CHNCH 2(4-ClC6H4) (1d) produced five-membered exo-metallacycles [PtCl{(2,6-Cl2C6H3)CHNCH 2C6H4}{SOMe2}] (2c) and [PtCl{(2,6-Cl2C6H3)CHNCH2(4′- ClC6H3)}{SOMe2}] (2d) when the reaction was carried out in methanol and seven-membered endo-platinacycles [PtCl{(MeC 6H3)ClC6H3CHNCH2C 6H4}{SOMe2}] (3c) and [PtCl{(MeC 6H3)ClC6H3CHNCH2(4′ -ClC6H3)}{SOMe2}] (3d) when toluene was used as a solvent. The reaction of 2,4,6-(CH3)3C 6H2CHNCH2(4-ClC6H4) (1e) produced in both solvents an exo-platinacycle [PtCl{(2,4,6-(CH3) 3C6H2)CHNCH2(4′-ClC 6H3)}{SO(CH3)2}] (2e). Cyclometallation of 4-chlorobenzylamine was also achieved to produce compound [PtCl{(4-ClC6H3)CH2NH2}{SOMe 2}] (2g). The reactions of endo- and exo-metallacycles with phosphines evidenced the higher lability of the Pt-N bond in exo-metallacycles while a comparative analysis of the crystal structures points out a certain degree of aromaticity in the endo-metallacycle. The Royal Society of Chemistry.
- Capape, Alejandro,Crespo, Margarita,Granell, Jaume,Font-Bardia, Merce,Solans, Xavier
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p. 2030 - 2039
(2008/02/10)
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- Synthesis, structures, and electronic spectroscopy of luminescent acetylene- and (buta-1,3-diyne)platinum complexes
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The electronic absorption and emission spectroscopy of a series of diphenylaceylene- and (buta-1,3-diyne)-Pt0 complexes (L)Pt[(1,2-η2)-R-(C≡C)n-R] and [(dppp)Pt] 2[μ-(1,2-η2):(3,4-η2)-R-(C≡C) 2-R] (R = Ph or CH3, L = dppp or (PPh3) 2, n = 1 or 2) was investigated. The structures of (dppp)Pt[(1,2-η2)-Ph-C≡C-Ph], (dppp)Pt[(1,2- η2)-PhC4Ph] and [(dppp)Pt]2[μ-(1,2- η2):(3,4-η2)-Ph-(C≡C)2-Ph] were characterized by X-ray diffraction. The complexes all display intense absorptions that were attributed to Pt→P(dπ*) and Pt→acetylene(πx*) transitions. Except for the CH 3C4CH3 complexes, the complexes all exhibit two emissions at 380-550 nm and 500-800 nm. The higher energy emission could arise from the 3[P(dπ*)→Pt] transition, and the lower energy emission, which has a longer lifetime than the higher energy one, was attributed to the 3[acetylene(πx*)→Pt] transition. The energy of the MLCT absorption and emission was affected by the electronic properties of the acetylenes and the ancillary phosphanes. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Zhang, Ke,Hu, Jian,Kwok, Chu Chan,Kwok, Yin Wong,Yip, John H. K.
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p. 384 - 393
(2007/10/03)
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- Unexpected PtII migration between the calixarene oxygen atoms
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Reaction between the 1,3-bis(trimethylsilyl) ether of calix[4]arene and platinum(II) difluoro complexes unexpectedly results in the formation of the 1,2-bridging platinum(II) calixarene complex, which, upon treatment with 2 equiv of acyl chloride, reinstates the 1,3-disubstitution pattern in the calixarene moiety.
- Kotzen, Natalie,Goldberg, Israel,Lipstman, Sofia,Vigalok, Arkadi
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p. 5266 - 5268
(2008/10/09)
-
- Synthesis and coordination chemistry of an alkyne functionalised bis(pyrazolyl)methane ligand
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The alkyne functionalised bidentate N-donor ligand (2-propargyloxyphenyl) bis(pyrazolyl)methane (L) was prepared in high yield from the reaction of (2-hydroxyphenyl)bis(pyrazolyl)methane with propargyl bromide in the presence of base. A series of transition-metal complexes including [MCl2L] (M = Cu, Co, Ni, Zn, Pt), [ML2](NO3)2 (M = Cu, Co, Ni, Zn), [AgL]NO3 and [Pd(L)(dppe)](OTf)2 were prepared and characterised by spectroscopic techniques. In addition, ligand L as well as the Co(ii) and Zn(ii) complexes [CoCl2L]2, [ZnCl 2L] were structurally characterized by single-crystal X-ray diffraction. The organometallic gold(i) and platinum(ii) acetylide complexes [Pz2CH(C6H4-2-OCH2CCAuPPh 3)] and trans-[{Pz2CHC6H4-2-OCH 2CC}2Pt(PPh3)2] were prepared from L and [AuCl(PPh3)] and trans-[PtCl2(PPh3) 2], respectively. Treatment of these complexes with [Pd(OTf) 2(dppe)] or [Cu(MeCN)4]PF6 results in formation of the cationic, mixed-metal complexes, which were isolated (Pt/Pd, Au/Pt) or detected by electrospray mass spectrometry (Au/Cu, Pt/Cu). The Royal Society of Chemistry 2006.
- Mohr, Fabian,Cerrada, Elena,Laguna, Mariano
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p. 5567 - 5573
(2008/02/10)
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- Platinum(II) and mixed platinum(II)/gold(I) σ-alkynyl complexes. The first anionic σ-alkynyl metal polymers
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The alkynes C6Me4(C≡CH)2-1,4, C 6Me4(C≡CH)2-1,2, and C6Me 3(C≡CH)3-1,3,5 react with cis-[PtCl 2(PAr3)2] and NHEt2 and a catalytic amount of CuI to give complexes trans-[Pt-(C≡CC6Me 4C≡CH-4)2(PAr3)2] [Ar = Ph (1a), C6H4Me-4 (To) (1b)], trans-[Pt(C≡CC 6Me4-C≡CH-2)2(PAr3) 2] [Ar = Ph (2a), To (2b)], and trans-[Pt{C≡CC 6Me3(C≡CH)2-3,5}2(PAr 3)2] [Ar = Ph (3a), To (3b)], respectively. The reactions of [Au(acac)PAr3] (acac = acetylacetonato) with complex la or lb (2:1) or with 3b (4:1) give the neutral mixed PtIIAuI 2 or PtIIAuI4 σ-alkynyl complexes trans- [Pt(C≡CC6Me4C≡CAuPAr 3-4)2(PAr3)2] [Ar = Ph (4a), To (4b)] or trans-[Pt{C≡CC6Me3(C≡CAuPTo 3)2-3,5}2(PTo3)2] (5b), respectively. Additionally, the replacement of the triarylphosphine ligands present in 1a, 2a, 4b, or 5b with various trialkylphosphines produces the homologous derivatives with PMe3 (1c, 2c, 4c, 5c), PEt3 (1d), or P(nBu)3 (1e), respectively. PPN[Au(acac) 2] reacts with complex 1a, 1c, or 1e (1:1) to give (PPN) n[trans-Pt{(C≡CC6Me4C≡C-4) 2Au}(PR3)2]n [R = Ph (6a), Me (6c), nBu (6e)], while its reaction with 3b (2:1) produces (PPN) 2n[trans-Pt{C≡CC6Me3(C≡C) 2-3,5Au2(PTo3)2]n (7). Complexes 6a, 6c, 6e, and 7 are the first anionic σ-alkynyl metal polymers described so far. The crystal structures of 1a·CHCl3, 2b·2CHCl3, and 4b·5CH2Cl2 have been determined. Each complex displays crystallographic inversion symmetry.
- Vicente, Jose,Chicote, Maria-Teresa,Alvarez-Falcon, Miguel M.,Jones, Peter G.
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p. 2764 - 2772
(2008/10/09)
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- Difluoro complexes of platinum(II) and -(IV) with monodentate phosphine ligands: An exceptional stability of d6 octahedral organometallic fluorides
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Complexes (R3P)2PtF2 were prepared by reaction of the corresponding diiodo precursors with AgF in dichloromethane. The intermediate formation of trans- and cis-(R3P)2Pt(I)F was also observed. All fluoro complexes demonstrate a strong preference for the cis-configuration (R = Ph or Et) unless a bulky phosphine ligand is used (R = i-Pr), in which case the trans complex was observed. The Pt(IV) difluoro compounds (R3P)2Ar2PtF2 were obtained by reacting the Pt(II) diaryl precursors with XeF2. The fluoro ligands are located in the trans-position relative to the aryl groups in the overall octahedral environment. The representative Pt(II) and Pt(IV) difluoro complexes were characterized by X-ray crystallography. All fluoro compounds react rapidly with chlorotrimethylsilane to give the corresponding chloro complexes. The Pt(IV) difluorides are remarkably stable in the C-C reductive elimination reaction, relative to their dichloro analogs which reductively eliminate diaryl within several hours at 45°C in N-methylpyrrolidone. It was found that phosphine dissociation from the octahedral Pt(IV) complex is essential for the reductive elimination reaction to take place, the difluoro complex being kinetically stable even at 60°C.
- Yahav, Anette,Goldberg, Israel,Vigalok, Arkadi
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p. 1547 - 1553
(2008/10/09)
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- Addition of tetrachloromethane to alkenes, catalyzed by Pt(II) complexes
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Platinum(II) complexes [dichlorobis(triphenylphosphine)platinum(II), dichlorobis(tri-m-tolylphosphine)platinum(II), dichloro(2,9-dimethyl-1,10-N, N′-phenanthroline)platinum(II), etc.] showed catalytic activity in addition of tetrachloromethane across the double bond in 1-hexene, 1-heptene, 1-octene, 1-decene, and cyclohexene. The stability of the platinum catalysts was evaluated by GLC, gas chromatography-mass spectrometry, and 31P NMR and IR spectroscopy; the kinetic relationships of the addition reactions were determined. A reaction mechanism involving formation of trichloromethyl radical was suggested. A correlation was revealed for the first time between the catalytic activity of platinum, palladium, and rhodium complexes and the capability of these complexes to generate hexachloroethane. 2005 Pleiades Publishing, Inc.
- Zazybin,Khusnutdinova,Osipova,Solomonov
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p. 734 - 738
(2007/10/03)
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- Synthesis and characterisation of the platinum complexes [PtCl(CCl=PAr)(PPh3)2] and [PtCl(CCl=PAr′)(PPh 3)2] as potential intermediates in the preparation of phosphaalkynes
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Oxidative addition reactions of Cl2CPR (R = 2,4,6- tris(trifluoromethyl)phenyl (Ar) or 2,6-bis(trifluoromethyl)phenyl (Ar′) with Pt(PPh3)4 yield the cis and trans (at platinum) complexes [PtCl(ClCPAr)(PPh3)2] and [PtCl(ClCPAr′) (PPh3)2]. All starting materials and intermediates have been characterised by NMR spectroscopy. The crystal and molecular structures of the trans-platinum complexes have been determined by single-crystal X-ray diffraction at low temperature.
- Cornet, Stéphanie M.,Dillon, Keith B.,Goeta, Andrés E.,Howard, Judith A.K.,Roden, Mark D.,Thompson, Amber L.
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p. 3630 - 3637
(2007/10/03)
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- Synthesis and characterisation of triselenocarbonate [CSe3] 2- complexes
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[Pt(CSe3)(PR3)2] (PR3 = PMe3, PMe2Ph, PPh3, P(p-tol)3, 1/2 dppp, 1/2 dppf) were all obtained by the reaction of the appropriate metal halide containing complex with carbon diselenide in liquid ammonia. Similar reaction with [Pt(Cl)2(dppe)] gave a mixture of triselenocarbonate and perselenocarbonate complexes. [{Pt(μ-CSe3)(PEt 3)}4] was formed when the analogous procedure was carried out using [Pt(Cl)2(PEt3)2]. Further reaction of [Pt(CSe3)(PMe2Ph)2] with [M(CO)6 (M = Cr, W, Mo) yielded bimetallic species of the type [Pt(PMe2Ph) 2(CSe3)M(CO)5] (M = Cr, W, Mo). The dimeric triselenocarbonate complexes [M{(CSe3)(η5-C 5Me5)}2] (M = Rh, Ir) and [{M(CSe 3)(η6-p-MeC6H4 iPr)}2] (M = Ru, Os) have been synthesised from the appropriate transition metal dimer starting material. The triselenocarbonate ligand is Se,Se' bidentate in the monomeric complexes. In the tetrameric structure the exocyclic selenium atoms link the four platinum centres together. The Soyal Society of Chemistry 2005.
- Burchell, Colin J.,Aucott, Stephen M.,Slawin, Alexandra M. Z.,Woollins, J. Derek
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p. 735 - 739
(2007/10/03)
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- The electron-poor phosphines P{C6H3(CF 3)2-3,5}3 and P(C6F 5)3 do not mimic phosphites as ligands for hydroformylation. A comparison of the coordination chemistry of P{C 6H3(CF3)2-3,5}3 and P(C6F5)3
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The fluoroaryl phosphines P{C6H3(CF3) 2-3,5}3 (La) and P(C6F 5)3 (Lb) form the complexes trans-[MCl 2(La)2] and trans-[MCl2(L b)2] (M = Pd or Pt) which have been isolated and fully characterised. 31P NMR studies of competition experiments show that the stability of trans-[PdCl2L2] is in the order L = Lb a 3. The crystal structure of trans-[PtCl2(La)2] is reported and reveals that the Pt-P bond lengths in trans-[PtCl2L2] are in the order L = Lb a 3. The equilibria established when [Pt(norbornene)3] is treated with La or Lb are investigated by 31P and 195Pt NMR spectroscopy and the species [PtLn(norbornene)3-n] (n = 1-3) identified. Ligands La and Lb appear to have similar affinities for platinum(0). The complexes trans-[MCl(CO)(La) 2] and trans-[MCl(CO)(Lb)2] (M = Rh or Ir) have been synthesised and fully characterised; the values of vco are comparable with those for analogous phosphite complexes. The ligands L a, Lb, P(C6H2F 3-3,4,5)3 (Lc), P{C6H 4(CF3)-2}3 (Ld), PPh3 and P(OPh)3 have been tested in rhodium-catalysed hydroformylation of 1-hexene and La, Lb, and PPh3 have been tested in rhodium-catalysed hydroformylation of 4-methoxystyrene. Ligands L a, and Lb, have been shown to be stable under the hydroformylation catalysis conditions. For the 1-hexene reaction, the activity and selectivity for La and Lc are very similar to the PPh3 catalyst (TOF ca. 400 h-1; n: iso 2.5-3.0) but for the sterically demanding Lb and Ld the activity and selectivity was much lower than with PPh3 (TOF ca. 15, n: iso ratio 0.6). Thus, the yield of heptanals obtained with the catalyst derived from La is 94% while under the same conditions with Lb only 6%. The TOF for the La/Rh catalyst was 5 times lower than for the P(OPh)3/Rh catalyst despite the superficially similar ligand electronic characteristics for La and P(OPh)3. The Royal Society of Chemistry 2005.
- Clarke, Matthew L.,Ellis, Dianne,Mason, Kate L.,Orpen, A. Guy,Pringle, Paul G.,Wingad, Richard L.,Zaher, Damien A.,Baker, R. Tom
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p. 1294 - 1300
(2007/10/03)
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- (Fluoren-9-ylidene)methanedithiolato complexes of platinum: Synthesis, reactivity, and luminescence
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Platinum(II) complexes with (fluoren-9-ylidene)methanedithiolato and its 2,7-di-tert-butyl- and 2,7-dimethoxy-substituted analogues were obtained by reacting different chloroplatinum(II) precursors with the piperidinium dithioates (pipH)-[(2,7-R2/su
- Vicente, Jose,Gonzalez-Herrero, Pablo,Perez-Cadenas, Maria,Jones, Peter G.,Bautista, Delia
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p. 7200 - 7213
(2008/10/09)
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- Platinum complexes having antitumor activity
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A platinum complex having antitumor activity in which the metal ligands are dehydrocholic acid and phosphine
- -
-
Page/Page column 3
(2008/06/13)
-
- Reactivity of the bis(pentafluorophenyl)boranes CIB(C6F 5)2 and [HB(C6F5)2] n towards late transition metal reagents
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The reactivities of the highly electrophilic boranes ClB(C 6F5)2 (1) and [HB(C6F 5)2]n. (2) towards a range of organometallic reagents featuring metals from Groups 7-10 have been investigated. Salt elimination chemistry is observed between 1 and the nucleophilic anions [(η5-C5R5)Fe(CO)2]- (R = H or Me) and [Mn(CO)5]-, leading to the generation of the novel boryl complexes (η5-C5R5)Fe(CO) 2B(C6F5)2 [R = H (3) or Me (4)] and (OC)5MnB(C6F5)2 (5). Such systems are designed to probe the extent to which the strongly σ-donor boryl ligand can also act as a π-acceptor, a variety of spectroscopic, structural and computational probes imply that even with such strongly electron withdrawing boryl substituents, the π component of the metal-boron linkage is a relatively minor one. Similar reactivity is observed towards the hydridomanganese anion [η5-C5H4Me)Mn(CO) 2H]-, generating a thermally labile product identified spectroscopically as (η5-C5H4Me)Mn(CO) 2(H)B(C6F5)2 (6). Boranes 1 and 2 display different patterns of reactivity towards low-valent platinum and rhodium complexes than those demonstrated previously for less electrophilic reagents. Thus, reaction of 1 with (Ph3)2Pt(H2C=CH 2) ultimately generates EtB(C6F5)2 (10) as the major boron-containing product, together with cis-(Ph 3P)2PtCl2 and trans-(Ph3P) 2Pt(C6F5)Cl (9). The cationic platinum hydride [(Ph3P)3PtH]+ is identified as an intermediate in the reaction pathway. Reaction of 2 with [(Ph3P) 2Rh(μ-Cl)]2, in toluene on the other hand, appears to proceed via ligand abstraction with both Ph3P·HB(C 6F5)2 (11) and the arene rhodium(I) cation [(Ph3P)2Rh(η-C6H5Me)] + (14) ultimately being formed.
- Al-Fawaz, Amal,Aldridge, Simon,Coombs, Deborah L.,Dickinson, Anthony A.,Willock, David J.,Ooi, Li-Ling,Light, Mark E.,Coles, Simon J.,Hursthouse, Michael B.
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p. 4030 - 4037
(2007/10/03)
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- Synthesis and characterisation of cyanodithioimidocarbonate [C2N2S2]2- complexes
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[PPh4]2[M(C2N2 S2)2] (M = Pt, Pd) and [Pt(C2N2S2) (PR3)2] (PR3 = PMe2Ph, PPh3) and [Pt(C2N2S2)(PP)] (PP = dppe, dppm, dppf) were all obtained by the reaction of the appropriate metal halide containing complex with potassium cyanodithioimidocarbonate. The dimeric cyanodithioimidocarbonate complexes [{Pt(C2N2S2) (PR3)}2] (PR3 = PMe2Ph), [M{(C2N2 S2)(η5-C5Me5)}2] (M = Rh, Ir) and [{Ru(C2N2S2) (η6-p-MeC6H41Pr)}2] have been synthesised from the appropriate transition metal dimer starting material. The cyanodithioimidocarbonate ligand is S,S and bidentate in the monomeric complexes with the terminal CN group being approximately coplanar with the CS2 group and trigonal at nitrogen thus reducing the planar symmetry of the ligand. In the dimeric compound one of the sulfur atoms bridges two metal atoms with the core exhibiting a cubane-like geometry.
- Burchell, Colin J.,Aucott, Stephen M.,Milton, Heather L.,Slawin, Alexandra M.Z.,Woollins, J. Derek
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p. 369 - 374
(2007/10/03)
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- Amine attack on coordinated alkenes: An interconversion from anti-Markovnikoff to Markovnikoff products
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A sequence of alkene complexes of platinum, PtCl2(PPh 3)(alkene) (alkene = ethylene, propene, 1-butene, cis-2-butene, 1-hexene, 1-octene, and 1-decene), has been prepared. These complexes are characterized by NMR spectroscopy, including assignment of each proton, and X-ray crystal structures of the 1-propene and 1-hexene complexes. Each complex was reacted with diethylamine. For the 1-hexene, 1-octene, and 1-decene complexes, the amine displaces the alkene. For the smaller alkenes, the diethylamine nucleophilically attacks the coordinated alkene. For propene and 1-butene, the low-temperature addition leads to the anti-Markovnikoff nucleophilic attack, which slowly converts at room temperature to the Markovnikoff product. The transformation from anti-Markovnikoff to Markovnikoff addition occurs without diethylamine dissociation.
- Pryadun, Ruslan,Sukumaran, Dinesh,Bogadi, Robert,Atwood, Jim D.
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p. 12414 - 12420
(2007/10/03)
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- Oxosulfido Complexes of Platinum - (Ph3P)2Pt(S 2O) and (Ph3P)4Pt2(μ-S)(μ-SO) - Their Formation and Properties
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The platinum S2O complex [(Ph3P)2Pt(S 2O)] (10) was obtained by S2O transfer reactions from tetrathiolane 2-oxide (8), tetrathiolane 2,3-dioxide (5), and pentathiane 3-oxide (6) to [(C2H4)Pt(PPh3)21] (4). The S2O complex 10 further reacts with 4 to give a novel binuclear platinum complex 16, which is found to be a source of several platinum SnOm complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Ishii, Akihiko,Murata, Masami,Oshida, Hideaki,Matsumoto, Kimiyo,Nakayama, Juzo
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p. 3716 - 3721
(2007/10/03)
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- Synthesis and characterization of new transplatinum complexes containing phosphane groups - Cytotoxic studies in cisplatin-resistant cells
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In this paper we report the synthesis and characterization of novel trans platinum(ii) complexes of general formula trans[PtCl2(L)(PPh3)], where L is NH2CH(CH3)CH2CH3 (complex 1), (R)-NH2CH(CH3)CH2CH3 (complex 2), (S)-NH2CH(CH3)CH2CH3 (complex 3) and NH2CH(CH3)2 (complex 4). The new complexes contain phosphane ligands trans to the amine group. X-ray crystal structure determinations of complexes 1 and 3 confirmed their trans configurations. The cytotoxic activity of these complexes have been evaluated and compared with the activity of trans platinum complexes already viewed as potential drugs. ( Wiley-VCH Verlag GmbH & Co, KGaA, 69451 Weinheim, Germany, 2003).
- Ramos-Lima, Francisco J.,Quiroga, Adoracion G.,Perez, Jose M.,Font-Bardia, Merce,Solans, Xavier,Navarro-Ranninger, Carmen
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p. 1591 - 1598
(2007/10/03)
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- Coordination isomerism in salicylhydroxamate complexes of platinum(II) and palladium(II)
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The syntheses of a range of platinum(II) and palladium(II) complexes containing salicylhydroxamate ligands are described. The ancillary ligands, together with the synthetic route, influence the coordination mode of the salicylhydroxamate ligand. Reaction of cis-[PtCl2(PPh3)2] with salicylhydroxamic acid and trimethylamine in hot methanol gave O,O′-bonded [Pt{OC(=NO)C6H4OH} (PPh3)2], but [PtCl2(cod)] (cod = cycloocta-1,5-diene) gave N,O-bonded [Pt{OC6H4C(O)NOH} (cod)]. Ligand substitution gives other N,O bonded complexes, including [Pt{OC6H4C(O)NOH}(PPh3)2]. Reaction of K2PtCl4 with 2 equiv. of EPh3 (E = As or Sb), salicylhydroxamic acid and excess trimethylamine gives products whose structures depend on E; AsPh3 gives [Pt{OC(=NO)C6H4-OH} (AsPh3)2], while SbPh3 gives [Pt{OC6H4C(O)NOH} (SbPh3)2].
- Henderson, William,Evans, Cameron,Nicholson, Brian K.,Fawcett, John
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p. 2691 - 2697
(2007/10/03)
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- Synthesis and crystal structure of the first complex containing a chelating selenourea dianion ligand
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Reaction of N,N′-diphenylselenourea, PhNHC(Se)NHPh, with cis-[PtCl2(PPh3)2] and triethylamine in hot methanol gives the first example of a selenourea dianion complex, [Pt{SeC(=NPh)NPh}(PPh3)2] isolated as a yellow solid in high yield. The structure of the complex was determined by X-ray crystallography and found to be similar to the related thiourea dianion complex [Pt{SC(=NPh)NPh}(PPh3)2], with a Pt-Se-C-N four-membered ring. The antitumour activity (P388 murine leukaemia cells) of the selenourea dianion complex was determined, together with a small selection of related platinum(II)-thiourea dianion complexes (prepared by an analogous method) for comparison. The complex [Pt{SC(=NMe)NMe}(PPh3)2] showed high activity [IC50 1.0 μM], with the other complexes showing moderate to low activity.
- Henderson, William,Nicholson, Brian K.,Dinger, Maarten B.
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p. 428 - 431
(2008/10/09)
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- PLATINUM COMPLEXES HAVING ANTITUMOR ACTIVITY
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A platinum complex having antitumor activity in which the metal ligands are dehydrocholic acid and a phosphine.
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Page/Page column 5
(2008/06/13)
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- Solvent-free mechanochemical synthesis of two Pt complexes: Cis-(PH3P)2PtCl2 and cis-(Ph3P)2PtCO3
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Cis-(Ph3P)2PtCl2 and cis-(Ph3P)2PtCO3 were prepared mechanochemically from solid reactants in the absence of a solvent; cis-(Ph3P)2PtCl2 was obtained in 98% yield after ball-milling of polycrystalline PtCl2 and Ph3P; the mechanically induced solid-state reaction of cis-(Ph3P)2PtCl2 with an excess of anhydrous K2CO3 produced cis-(Ph3P)2PtCO3 in 70% yield; the formation of transition metal complexes as a result of mechanochemical solvent-free reactions has been confirmed by means of solid-state 31P MAS NMR spectroscopy, X-ray powder diffraction and differential thermal analysis.
- Balema, Viktor P.,Wiench, Jerzy W.,Pruski, Marek,Pecharsky, Vitalij K.
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p. 1606 - 1607
(2007/10/03)
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- X-ray structures of the first platinum complexes with Z configuration iminoether ligands: Trans-dichlorobis(1-imino-1-methoxy-2,2′dimethylpropane)platinum(II) and trans-Tetrachlorobis(1-imino-1methoxy-2,2′-dimethylpropane)platinum(IV)
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Platinum complexes with Z configuration iminoether ligands (trans-[PtCl2{HN=C(OMe)Bu1}2], 1, and trans-[PtCl4-{HN=C(OMe)Bu1}2], 2) have been structurally characterized for the first time. The nearly planar Pt-N-C-O-C chain, all atoms being in gauche conformation, brings the terminal Pt and C atoms very close to one another. The steric clash is released by considerably increasing the Pt-N-C, N-C-O, and C-O-C bond angles (133, 124, and 121° for 1, respectively; 147, 129, and 127° for 2, respectively), which are well above the expected values (120° for Pt-N-C and N-C-O; less than 120° for C-O-C owing to the repulsive effect exerted by the lone pair of electrons on the oxygen atom). In the platinum(II) case the smaller increase of bond angles is accompanied by a greater value of the Pt-N-C-O torsion angle (27.3 and 15.6° for 1 and 2, respectively). The stabilization of the Z configuration, notwithstanding the steric clashes described above, has been achieved by a careful choice of the R substituent in the iminoether moiety (a bulky tert-butyl group). The reactions of the platinum(IV) species (2) in basic and acidic conditions and with triphenylphosphine have been investigated. Bases and acids both interact with the coordinated ligand in such a way to weaken the coordinative bond and promote the release of the iminoether ligands. The phosphine promotes a ready and complete reduction of the platinum(IV) complex to the corresponding platinum(II) species (1). Compound 1 reacts with a stoichiometric amount of phosphine (1:1 molar ratio) to form cis-[PtCl2(PPh3){Z-HN=C(OMe)Bu1}] and with excess phosphine to form [PtCl2(PPh3)2] and free iminoether. The latter two reactions leading to formation of a mixed phosphine/iminoether platinum species and to free iminoether, which can be used as a synthon for further organic transformations, can be of synthetic utility.
- Gonzalez, Ana M.,Cini, Renzo,Intini, Francesco P.,Pacifico, Concetta,Natile, Giovanni
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p. 470 - 478
(2008/10/08)
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- Reactions of organotin(IV) compounds with platinum complexes. Part(III). Reactions of (R2Sn)n, (R = Me or Ph, n = 6; R = Et, n = 9) with platinum complexes
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The R2Sn moieties formed when the cyclic compounds (R2Sn)n, R = Me or Ph, n = 6; R = Et, n = 9, are exposed to light, react with the platinum(II) complexes [PtCl2L2], L = PEt3, PPr3, PBu3, PEtPh2, PPh3 to give new complexes of the general formula [PtCl(SnR2Cl)L2]. Similarly, Et2Sn from (Et2Sn)9 reacts with [PtMe(Cl)L2] to give [PtMe(SnEt2Cl)L2] and Ph2Sn from (Ph2Sn)6 reacts with [PtPh(Cl)L2] or [PtPh2L2] to give [PtPh(SnPh2Cl)L2] or [PtPh(SnPh3)L2] (L = PEt3), respectively. Reactions involving (R2Sn)n and the bridged complex [{Pt(μ-Cl)ClL}2] give a mixture of [PtCl(SnR2Cl)L2] and [PtCl(SnRCl2)L2], R = Me or Et, L = PBu3. It is suggested that these reactions initially involve insertion of R2Sn moieties into Pt-Cl bonds of the complexes [PtX(Cl) L2] or [{Pt(μ-Cl)ClL}2] then generate R2SnXCl (X = Cl, Me, Ph) and the Pt(0)complex [PtL2], which undergoes oxidative-addition of the formed tin(IV) species to give complexes containing Pt-Sn bonds. With (Ph2Sn)6 and [PtPh2L2], the mechanism takes a different course. Reactions under similar conditions involving the Pt(0) complexes [Pt(C2H4(PPh3)2] or [Pt(COD)2], (COD = 1,5-cyclooctadiene) and (R2Sn)6, R = Me or Ph, gave no detectable complexes containing Pt-Sn bonds. The complex [Pt(PEt3)4] and (MeSn)6 likewise gives no species containing Pt-Sn bonds but with (Ph2Sn)6, two complexes, tentatively identified as trans-[PtPh(Sn2Ph5)(PEt3)2] and trans-[PtPh(Sn6Ph11)(PEt3)2], were detected in the solution. In all cases, the products were identified by 31P-NMR spectroscopy.
- Al-Allaf, Talal A.K
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- Metal complexes of functionalized sulfur containing ligands, XV [1]. Reactions of platinum(0) complexes with 1,2,4-trithiolanes, 1,2,4,5-tetrathianes, 1,2,3,5,6-pentathiepanes as well as thioketones. X-ray structure analysis of (Ph3P)2Pt(η2-Ph2C=S)
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3,3,5,5-Tetraphenyl-1,2,4-trithiolane (1) reacts with twofold excess of (Ph3P)2Pt(η2-C2H4) (4) to give a 1:1 mixture of the complexes (Ph3P)2Pt(SCPh2S) (6a) and (Ph3P)2Pt(η2-Ph2C=S) (7a). Treatment of 3,3,6,6-tetraphenyl-1,2,4,5-tetrathiane (2) with a fourfold excess of 4 yields [Pt2(PPh3)4(μ-S)2] (8) and the platinum(0) compound 7a. The reaction of the 1,2,3,5,6-pentathiepane 3 with a fourfold excess of 4 affords a 1:1:1 mixture of 8, the platinum(0) complex 7b and the bis-thiolato platinum(II) complex 6b. The thioketone complexes 7a-c were formed in smooth reactions of 4 with the thioketones 5a-c. The molecular structure of (Ph3P)2Pt(η2-Ph2C=S) (7a) has been established by single-crystal X-ray analysis.
- Weigand, Wolfgang,Wünsch, Ralf,Robl, Christian,Mloston, Grzegorz,N?th, Heinrich,Schmidt, Manfred
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p. 453 - 458
(2007/10/03)
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- Synthesis, characterisation and coordination chemistry of novel chiral N,N-dialkyl-N′-menthyloxycarbonylthioureas. Crystal and molecular structures of N,Ndiethyl-Ar'-(-)-(3/?)-menthyloxycarbonylthiourea and m-(S,S)-[Pt(L)CI(DMSO)] [where HL = N-(+)(3JR)-menthyloxycarbonyl-A'-morpholinothiourea or W-benzoylAr',W-diethylthiourea]
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The novel ligands N,N-diethyl-N-(-)-(3fl)-menthyloxycarbonylthiourea (HL3), N,N-dklhyl-N'-(+)-(3R)-menthyoxycarbonylthiourea (HL4), AH-HS/-menthyloxycarbonyl-N'-morpholinothiourea (HL5) and N-(+)-(3R)menthyloxycarbonyl-W-morpholinothiourea (HL6) have been prepared and characterised. The molecular structure of HL3 has been confirmed by X-ray crystallography. The reaction of these Ar,Ar-disubstituted-Ar'-menthyloxycarbonylthiourea ligands with m-[PtQ2(DMSO)J in the presence of sodium acetate yields geometric isomers of the resultant (Pt(L)Cl(DMSO)] complexes, that is the DMSO is sulfur bonded to the platinum in either a cw-(S,S) or trans-(S,S) arrangement with respect to the sulfur donor atom of the chelated ligand. This is in contrast to the complexation reaction of c-[PtCI2(DMSO)2] with A'-benzoyl-AN'-diethylthiourea (HL1) or W-benzoyl-A morpholinothiourea (HL2) which yields only one [Pt(L)Cl(DMSO)] complex in which the DMSO is in a ra-(S,S) arrangement with respect to the sulfur donor atom of the chelated ligand. The molecular structures of c/s-(S,S)(Pt(L)Cl(DMSO)], where L = (L')- or (L6)-, have been determined by X-ray crystallography. The difference in the coordination chemistry of the acylthiourea and alkoxycarbonylthiourea ligands has been examined further by treating the [Pt(L)Cl(DMSO)] complexes with PPh3 to give the corresponding mono- and bis-(phosphine) complexes, [Pt(L)Cl(PPhj)] and [Pt(L)(PPh3)2] The 3IP NMR studies of these complexes reveal that the alkoxycarbonylthiourea ligands bind less strongly than the acylthiourea ligands, which is consistent with the crystallographic studies. The weaker binding properties of the alkoxycarbonylthiourea ligands might be a possible explanation for the observed geometric isomerisation of the complexes and that the mechanism could involve a chelate ring opening step. The Royal Society of Chemistry 2000.
- Sacht, Cheryl,Datt, Michael S.,Otto, Stcfanus,Roodt, Andreas
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p. 4579 - 4586
(2007/10/03)
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