- Reactions of tBu2P-PLi-PtBu2 with [(Et3P)2MCl2] (M = Ni, Pd, Pt). Synthesis and properties of [(1,2-η-tBu2P=P-PtBu 2)M(PEt3)Cl] (M=Ni, Pd)
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tBu2P-PLi-PtBu2·2THF reacts with [cis-(Et3P)2MCl2] (M = Ni, Pd) yielding [(1,2-η-tBu2P=P-PtBu 2)Ni(PEt3)Cl] and [(1,2-η-tBu 2P=P-PtBu2)Pd(PEt3)Cl], respectively. tBu2P-PLi-tPBu2 undergoes an oxidation process and the tBu2P-P-PtBu 2 ligand adopts in the products the structure of a side-on bonded 1,1-di-tert-butyl-2-(di-tert-butylphosphino)diphosphenium cation with a short P-P bond. Surprisingly, the reaction of tBu2P-PLi-P tBu2·2THF with [cis-(Et3P) 2PtCl2] does not yield [(1,2-η-tBu 2P=P-PtBu2)Pt(PEt3)Cl].
- Baum, Elke,Matern, Eberhard,Robaszkiewicz, Andrzej,Pikies, Jerzy
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- Analysis of a hydrodesulfurization process. 3. Acid cleavage of thiaplatinacycles
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Reaction of the thiaplatinacyle [(Et3P)2Pt(C12H8S-C,S)] (3; derived from reaction of [Pt-(Et3P)3] and dibenzothiophene (DBT)) with HCl gives largely 2-phenylthiophenol and a small amount of DBT. The thiaplatinacycle [(Et3P)2Pt(C8H6S-C,S)] (2; from benzothiophene (BT)) undergoes reaction with HCl to give 2,3-dihydrobenzothiophene (22%), a small amount of 2-vinylthiophenol, and BT, while the thiaplatinacycle [(Et3P)2Pt(C4H4S-C,S)] (1; from thiophene) regenerates thiophene with HCl; in each case the metal is found as [(Et3P)2-PtCl2]. In contrast all the thiaplatinacycles react very similarly with HBF4 to give dinuclear [Pt2(Et3P)4(μ-SR)2](BF 4)2 (7c, R = 2-phenylthiophenolate (from 3); 7b, R = 2-vinylthiophenolate (from 2); 7a, R = 1-thiolatobutadiene (from 1)). An X-ray structure determination of 7c confirmed the structure. Reaction of the dications 7a-c with HCl gave C4H6S (59%), 2-vinylthiophenol (83%), and 2-phenylthiophenol (91%), respectively.
- Garcia, Juventino J.,Arevalo, Alma,Montiel, Virginia,Del Rio, Federico,Quiroz, Beatriz,Adams, Harry,Maitlis, Peter M.
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- Equilibria of the thiametallacycles with tris(triethylphosphine)platinum(0) and dibenzothiophene, benzothiophene, or thiophene: The hydrodesulfurization reaction
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The thiaplatinacycles, [(PtSC12H8)(PEt3)2], 1, [(PtSC8H6)(PEt3)2], 2, and [(PtSC4H4)(PEt3)2], 3, in which Pt(PEt3)2 has inserted into one C-S bond of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T), respectively, are formed by the reversible reaction of tris(triethylphosphine)platinum(0) with the thiophene. The structure of complex [(PtSC8H6)(PEt3)2] (2) was confirmed by an X-ray determination that showed a square-planar Pt(II) bound to two cis PEt3 ligands, and to the S and the CH=, in a six-membered Pt-S-C-C-C-C ring [Pt-S(1), 2.315(5) ?; Pt-C(4), 2.035(19) ?; Pt-P(1), 2.301(5) ?, trans to S(1); and Pt-P(2), 2.386(5) ?, trans to C(4); P(1)-Pt-P(2), 97.6(2)°; S(1)-Pt-P(2), 87.0(2)°; S(1)-Pt-C(4), 88.6(6)°; P(1)-Pt-C(4), 86.8(6)°]. The adducts 1 and 3, derived from DBT and T, have been shown to have similar structures spectroscopically. The free thiophenes and Pt(PEt3)3 are regenerated on heating complexes 1-3 with Et3P; [(PtSCaHb)(PEt3)2] + Et3P ? [Pt(Et3P)3] + SCaHb. Keqm = [Pt(Et3P)3][SCaHb]/[PtSCaH b)(PEt3)2][Et3P] and is 10 for 1 (DBT) and 3 (T) and 1 for 2 (BT) at 100 °C. The complexes 1-3 undergo a variety of cleavage reactions; thus, the Pt-C bond in 1 is cleaved by HCl to give 2-phenylthiophenol and [Pt(PEt3)2Cl2], and all three complexes are degraded by hydride reagents to give the completely desulfurized hydrocarbons: biphenyl from 1, styrene and ethylbenzene from 2, and butadiene and butenes from 3. When the reactions are carried out with Et3SiH as reducer, the complex [Pt(SH)(H)(PEt3)2] is identified among the products, together with [Pt(Et3Si)(H)(PEt3)2], The former is a coproduct of the desulfurization, while the latter arises from addition of Et3SiH to [Pt(PEt3)2] (from reversal of the formation of [(PtSCaHb))(PEt3)2]) and is accompanied by the formation of the free thiophene. Under comparable conditions, the amount of desulfurization decreases in the order BT complex 2 (73%) > DBT complex 1 (50%) > T complex 3 (ca. 4%). These hydride reactions show the novel feature that the C-S bond is cleaved as well as the Pt-C bond; possible mechanisms for the platinum and for the known nickel- and hydride-promoted hydrodesulfurization (HDS) reactions are discussed.
- Garcia, Juventino J.,Mann, Brian E.,Adams, Harry,Bailey, Neil A.,Maitlis, Peter M.
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- Ligand effects on the rates of protonolysis and isotopic exchange for platinum (II) alkyls
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The protonolysis/deuterolysis of complexes L2PtRX (L = phosphorus ligand, R = alkyl group, X = anionic ligand) has been investigated as a mechanistic probe of the reverse reaction, activation of alkanes by Pt(II). Trans-(Et3P)2PtMeX (X- = triflate (OTf-), F-, NO3-) solvolyze in acidic CD3OD, forming [trans-(Et3P)2PtMe(CD3OD)]+ which reacts slowly with DOTf at room temperature liberating CH3D. In dichloromethane, trans-(Et3P)2PtMe(OTf) reacts with HOTf at low temperatures (-70 to -20°C) to give (Et3P)2PtMe(H)(OTf)2 in rapid equilibrium with the reagents, while at higher temperatures rapid methane loss is preceded by extensive deuterium incorporation (with DOTf) into the Pt(II) methyl group. Upon treatment with acid in CD3OD, trans-(Et3P)2PtMeX (X = Cl, Br) also undergo H/D exchange before elimination of methane, while trans-(Et3P)2PtMeI, (depe)Pt(CH3)2 (depe=1,2-bis(diethylphosphino)ethane) and cis-[(MeO)3P]PtMeCl do not. The a hydrogens of trans-(Et3P)2PtRCl (R=Me, Et, Bz) exchange with deuterium in CD3OD/DOTf with rates following the order Bz3P)2Pt(CH2CMe3)Cl which yields (CH3)3CCH2D. These trends are interpreted in terms of effects on relative stabilities of key intermediates, Pt(IV) alkyl hydrides and Pt(II) alkane sigma complexes.
- Holtcamp, Matthew W.,Labinger, Jay A.,Bercaw, John E.
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- Thermal Cis-Trans Isomerization of Dihalogenobisplatinum(II) in the Solid State
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Solid-state thermal cis-trans isomerization of the platinum(II) complexes of the type were investigated by means of DSC methods, where X is Cl, Br, or I; R is CH3, C2H5, n-C3H7, n-C4H9, or C6H5.High isomerization ratios (93-100 percent) were
- Fushimi, Masaki,Suzuki, Masatatsu,Uehara, Akira
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- A dynamic disorderlinked reversible phase transition in a new chloroform solvate of cisdichloridobis(triethylphosphane)platinum(II)
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The title compound, cisdichloridobis(triethylphosphane)platinum(II) chloroform monosolvate, [PtCl2(C6H15P) 2]·CHCl3, has been obtained from ligand scrambling in the cis-[PtCl2(Cyp2PCl)(PEt3)] (Cyp = cyclopentyl) system in CHCl3 solvent. Unlike the two previously reported unsolvated polymorphs, which are both monoclinic, the compound crystallizes in an orthorhombic setting. Furthermore, the system exhibits a reversible temperaturedependent structural phase transition, coupling a reduction in anisotropic displacement parameters and a reduction in crystallographic symmetry on cooling. The hightemperature phase adopts space group Pnma with the complex and solvent molecules sitting across a crystallographic mirror plane (Z′ = 0.5). The low-temperature phase adopts the space group P212121 with Z′ = 1.
- Dillon, Keith B.,Howard, Judith A. K.,Monks, Philippa K.,Probert, Michael R.,Shepherd, Helena J.
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- Photoreduction of Pt(IV) chloro complexes: Substrate chlorination by a triplet excited state
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The Pt(IV) complexes trans-Pt(PEt3)2(Cl) 3(R) 2 (R = Cl, Ph, 9-phenanthryl, 2-trifluoromethylphenyl, 4-trifluoromethylphenyl, 3-perylenyl) were prepared by chlorination of the Pt(II) complexes trans-Pt(PEt3)2(R)(Cl) 1 with Cl 2(g) or PhICl2. Mixed bromo-chloro complexes trans,trans-Pt(PEt3)2(Cl)2(Br)(R) (R = 9-phenanthryl, 4-trifluoromethylphenyl), trans,cis-Pt(PEt3) 2(Cl)2(Br)(4-trifluoromethylphenyl), trans,trans- Pt(PEt3)2(Br)2(Cl)(R) (R = 9-phenanthryl), and trans,cis-Pt(PEt3)2(Br)2(Cl)(4- trifluoromethylphenyl) were obtained by halide exchange or by oxidative addition of Br2 to 1 or Cl2 to trans-Pt(PEt3) 2(R)(Br). Except for 2 (R = Ph, 4-trifluoromethylphenyl), all of the Pt(IV) complexes are photosensitive to UV light and undergo net halogen reductive elimination to give Pt(II) products, trans-Pt(PEt3) 2(R)(X) (X = Cl, Br). Chlorine trapping experiments with alkenes indicate a reductive-elimination mechanism that does not involve molecular chlorine and is sensitive to steric effects at the Pt center. DFT calculations suggest a radical pathway involving 3LMCT excited states. Emission from a triplet is observed in glassy 2-methyltetrahydrofuran at 77 K where photoreductive elimination is markedly slowed.
- Perera, Tharushi A.,Masjedi, Mehdi,Sharp, Paul R.
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supporting information
p. 7608 - 7621
(2014/08/05)
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- Towards a catalytic hydrogenolysis of silicon-silicon bonds: Formation of Si-H bonds from disilanes and H2 at platinum
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Reactions of the disilanes Cl2MeSiSiMeCl2, ClMe 2SiSiMe2Cl and Me3SiSiMe3 led to the products of oxidative addition cis-[Pt(SiMeCl2)2(PEt 3)2] (2
- Roscher, Anja,Bockholt, Andreas,Braun, Thomas
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p. 1378 - 1382
(2009/06/06)
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- Reactions of R2P-P(SiMe3)2 with [(R3′ P)2 PtCl2]. Syntheses and structures of [μ2-(1,2:2-η-P2){Pt(PEt3) 2}2{Pt(PEt3
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Full title: Reactions of R2P-P(SiMe3)2 with [(R3′ P)2 PtCl2]. Syntheses and structures of [μ2-(1,2:2-η-P2){Pt(PEt3) 2}2{Pt(
- Domańska-Babul, Wioleta,Chojnacki, Jaroslaw,Matern, Eberhard,Pikies, Jerzy
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p. 3640 - 3648
(2008/02/08)
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- Multiple coordination modes of hemilabile 3-dimethylaminopropyl chalcogenolates in platinum(II) complexes: Synthesis, spectroscopy and structures
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The reactions of N,N-dimethylaminopropyl chalcogenolates with platinum(II) compounds have been carried out and complexes of the types [PtCl(ECH2CH2CH2NMe2)]2 (1) (E = S (1a) and Se (1b)), [Pt(ECH2CH2CH2NMe2)2]n (2) (E = S (2a) and Se (2b)), [(PtCl2)2{(Me2NCH2CH2CH2E)2}]n (3), [PtX(SeCH2CH2CH2NMe2)]2 (4) (X = SePh (4a) and OAc (4b)) and [PtCl(ECH2CH2CH2NMe2)(PR3)]n (5) (E = S, Se, Te) have been isolated. These complexes have been characterized by elemental analysis, IR, UV-Vis, NMR (1H, 13C, 31P, 77Se, 195Pt) spectroscopy and FAB mass spectral data. The structures of [PtCl(SeCH2CH2CH2NMe2)]2 (1b) and [PtCl(SCH2CH2CH2NMe2)(PPr3)]2 (5a) have been established by single crystal X-ray diffraction data. Both the molecules have dimeric structures. In 1b, two platinum atoms are held together by symmetrically bridging Se atoms of the chelating selenolate groups. In 5a, two thiolates form a four-membered Pt2S2 bridge with dangling NMe2 groups.
- Dey, Sandip,Jain, Vimal K.,Butcher, Ray J.
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p. 2653 - 2660
(2008/10/09)
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- Homo- and hetero-, bi- and tri-nuclear palladium(II) and platinum(II) complexes containing single bridging chalcogenolate of a metallo-ligand, [MCl(ECH2CH2NMe2)(PR3)] (M = Pt, Pd; E = Se, Te)
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Bi- and tri-nuclear palladium/platinum complexes of the types [MCl(ECH2CH2NMe2)(PR3)M′Cl2(PR3)] (M, M′ = Pd or Pt) and [{PtCl(SeCH2CH2NMe2)(PR3)}2M′ Cl2] (M′ = Pd or Pt; PR3 = PEt3 or PPr3n) have been prepared. All complexes were characterized by elemental analysis, NMR (1H, 31P, 77Se, 125Te, 195Pt) data. The structures of [PdCl(SeCH2CH2NMe2)(PPh3)PtCl2(PPh3)] and [{PtCl(SeCH2CH2NMe2)(PEt3)}2PtCl2] have been established by single crystal X-ray diffraction analysis. In the latter complex, three square planar platinum atoms are held together by the single bridging selenolate group in an almost linear chain arrangement.
- Dey, Sandip,Jain, Vimal K.,Butcher, Ray J.
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p. 1385 - 1390
(2008/10/09)
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- 1,1,2,2-tetramethyl-1,2-bis(phenylthiomethyl)disilane, a flexible ligand for the construction of macrocyclic, mesocyclic, and bridged dithioether complexes. Synthesis of the bis-silylated olefins Z-(PhSCH2)Me 2SiC(H)=C(Ar)SiMe2(CH2SPh) by catalytic activation of the Si-Si bond
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The functionalized disilane (PhSCH2)Me2SiSiMe 2(CH2SPh) (1) has been prepared and coordinated as a dithioether ligand on [PtCl2(PhCN)2] to afford the fluxional seven-membered chelate complex cis-[PtCl2{(PhSCH 2)2Si2Me4}] (2a). After metathesis reaction of 2a with NaI the diiodo derivative cis-[PtI2{(PhSCH 2)2Si2Me4}] (2b) was obtained. Treatment of [Re(μ-Br)(CO)3THF]2 with 1 equiv of 1 yields the bromo-bridged dinuclear complex fac-[{Re(μ-Br)(CO) 3}2{μ-(PhSCH2)2Si 2Me4}] (5), which is spanned by 1 forming a 10-membered mesocycle. Addition of a further equivalent of 1 yields the dinuclear macrocyclic compound fac-[{ReBr(CO)3}2{μ-(PhSCH 2)2Si2Me4}2] (4), forming a 14-membered ring system. The chloro-bridge of [RuCI(μ-Cl)(CO) 3]2 is cleaved by 1 to give the dinuclear compound fac-[{RuCl2(CO)3}2{μ-(PhSCH 2)2Si2Me4}] (6), in which the two metal fragments are linked by the thioether functions. In the presence of catalytic amounts of Pd(OAc)2/CNR, the Si-Si bond of 1 is cleaved and addition across the triple bond of phenylacetylene or p-tolylacetylene affords the bis-silylated olefins Z-(PhSCH2)Me2SiC(H)=C(Ar) SiMe2(CH2SPh) (7a Ar = Ph; 7b Ar = p-Tol). The new compounds have been studied by multinuclear NMR techniques; the crystal structures of 2a, 2b, 4, 5, 6, and 7a have been determined by X-ray diffraction studies.
- Peindy, Harmel N.,Guyon, Fabrice,Jourdain, Isabelle,Knorr, Michael,Schildbach, Daniel,Strohmann, Carsten
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p. 1472 - 1479
(2008/10/09)
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- Mechanistic insight into the protonolysis of the Pt-C bond as a model for C-H bond activation by platinum(II) complexes
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The kinetic and NMR features of the protonolysis reactions on platinum(II) alkyl complexes of the types cis-[PtMe2L2], [PtMe 2(L-L)], cis-[PtMeClL2], and [PtMeCl(L-L)] (L = PEt 3, P(Pri)3, PCy3, P(4-MePh) 3, L-L = dppm, dppe, dppp, dppb) in methanol suggest a rate-determining proton attack at the Pt - C bond. In contrast, a multistep oxidative-addition - reductive-elimination mechanism characterizes the methane loss on protonation of the corresponding trans-[PtMeClL2] species. Tools that were particularly diagnostic in suggesting different reaction pathways for the two systems were (i) the different results of kinetic deuterium isotope experiments, (ii) the detection or absence of Pt(IV) hydrido alkyl intermediate species by low-temperature 1H NMR experiments, and (iii) the detection or absence of isotope scrambling and incorporation of deuterium into Pt - CH3, combined with the loss of a range of CH nDn-4 isotopomers. For all systems, the rates of protonolysis are retarded by ligand steric congestion, accelerated by ligand electron donation, and almost unaffected by the chain length along the series of chelate complexes. A straight line correlates the rates of protonolysis of cis-dialkyl and cis-monoalkyl complexes, the difference in reactivity between the two systems being almost 5 orders of magnitude (slope of the line = 6 × 104). Factors controlling the dichotomy of behavior between complexes of different geometry have been taken into consideration. Application of the principle of microscopic reversibility suggests the reason why platinum complexes with nitrogen donor ligands appear to be far more efficient than platinum phosphane complexes in activating the C-H bond.
- Romeo, Raffaello,D'Amico, Giuseppina
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p. 3435 - 3446
(2008/10/09)
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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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- (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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- Self-assembly and anion encapsulation properties of cavitand-based coordination cages
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Two novel classes of cavitand-based coordination cages 7a-j and 8a-d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P-M-P angle close to 90° between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic 1H and 19F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d revealed the presence of a single triflate anion encapsulated. Guest competition experiments revealed that the encapsulation preference of cages 7b,d follows the order BF4- > CF3SO3- ? PF6- at 300 K. ES-MS experiments coupled to molecular modeling provided a rationale for the observed encapsulation selectivities. The basic selectivity pattern, which follows the solvation enthalpy of the guests, is altered by size and shape of the cavity, allowing the entrance of an ancillary solvent molecule only in the case of BF4-.
- Fochi,Jacopozzi,Wegelius,Rissanen,Cozzini,Marastoni,Fisicaro,Manini,Fokkens,Dalcanale
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p. 7539 - 7552
(2007/10/03)
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- Coordination chemistry of P-rich phosphanes and silylphosphanes. XXI [1] the influence of the PR3 ligands on formation and properties of the phosphinophosphinidene complexes [{η2-tBu2P-P}Pt(PR3)
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(R3P)2PtCl2 and C2H4 yield the compounds [{η2-C2H4}Pt(PR3)2] (PR3 = PMe3, PEt3, PPhEt2, PPh2/su
- Matern, Eberhard,Pikies, Jerzy,Fritz, Gerhard
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p. 2136 - 2142
(2008/10/08)
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- Intramolecular hydroamination of alkynes catalysed by late transition metals
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The cyclisation of 6-aminohex-1-yne to 2-methyl-1,2-dehydropiperidine in the presence of late transition metal catalysts was examined. The highest catalytic activity was observed for [Cu(CH3CN)4]PF6, as well as with Group 12 metal salts. Slightly lower conversions were obtained with the rhodium(I) and palladium(II) complexes [Rh(COD)(DiPAMP)]BF4 and [Pd(Triphos)][BF4]2. Catalysis was also observed with complexes of all group 9 to 12 metals and [Ru3(CO)12]. All catalytically active complexes contain a metal with a d8 or d10 electronic configuration. This observation allows preliminary conclusions about the mechanism to be made.
- Mueller, Thomas E.,Pleier, Anna-Katharina
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p. 583 - 587
(2007/10/03)
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- Synthesis of a tri(organoplatinum) complex via the double directed lithiation of a mono(organoplatinum) precursor
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The new diarylplatinum complex cis-[Pt(PEt3)2{C6H3(CH 2NMe2)2-3,5})2] 1, containing four free amine coordination sites, undergoes directed lithiation with But/su
- James, Stuart L.,Veldman, Nora,Spek,Van Koten, Gerard
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p. 253 - 255
(2007/10/03)
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- Exploring the mechanism of aqueous C-H activation by Pt(II) through model chemistry: Evidence for the intermediacy of alkylhydridoplatinum(IV) and alkane σ-adducts
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The protonolysis mechanisms of several alkylplatinum(II) complexes [(tmeda)PtMeCl (2) (tmeda = N,N,N',N'-tetramethylethylenediamine), (tmeda)Pt(CH2Ph)Cl (5), (tmeda)PtMe2 (11), and trans-(PEt3)2Pt(CH3)Cl (15)] in CD2Cl2 and CD3OD have been investigated. These reactions model the microscopic reverse of C-H activation by aqueous Pt(II). Each of the four systems (2 in CD3OD, 5 in CD2Cl2, 11 in CD3OD, and 15 in CD3OD) exhibits different behavior in the protonolysis reaction as observed by low-temperature 1H NMR spectroscopy. Protonolysis of 2 in methanol-d4 proceeds with no observable intermediates. Reversible reaction between 5 and HCl in CD2Cl2 at -78°C produces (tmeda)Pt(CH2Ph)(H)Cl2 (6), which undergoes reductive elimination of toluene at higher temperatures. Treatment of 11 with HCl in methanol at -78°C generates (tmeda)PtMe2(H)Cl (12), which incorporates deuterium from solvent (CD3OD) into the methyl groups prior to reductive elimination of methane. Finally, 15 reacts with H+ in methanol to liberate methane with no intermediates observed. However, hydrogen/deuterium exchange takes place between the solvent (CD3OD) and Pt-Me prior to methane loss. Each of these reactions was evaluated further to determine the kinetics of the reaction, activation parameters, and isotope effects. Based on the results, a common mechanistic sequence is proposed to operate in all the reactions: (1) chloride- or solvent-mediated protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, five-coordinate platinum(IV) species, (3) reductive C-H bond formation producing a platinum(II) alkane σ-complex, and (4) loss of alkane either through an associative or dissociative substitution pathway. The characteristics of each system differ due to changes in the relative stabilities of the intermediates and/or transition states upon varying the solvent or alkylplatinum species.
- Stahl, Shannon S.,Labinger, Jay A.,Bercaw, John E.
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p. 5961 - 5976
(2007/10/03)
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- Synthesis, reactions, and rearrangement of X(PR′3)2M[C(=PR)X] (M = Pt, Pd; X = Cl, Br; R′ = Et, Ph; R = 2,4,6-tri-tert-butylphenyl): Mechanism of the transition metal promoted conversion of X2C=PR to R-C≡P
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Oxidative addition reactions of X2C=PR (X = Cl, Br; R = 2,4,6-tri-tert-butylphenyl) with M(PEt3)4 (M = Pt, Pd) or (C2H4)Pt(PPh3)2 initially yield the cis isomer of square planar (X)-(PR′3)2M[C(=PR)X] (II); these complexes (IIa-IId), where PR′3 is PEt3, rearrange rapidly in the presence of free PEt3 to give the trans isomers (Ia-Id). In contrast, the cis isomers (IIe and IIf), where PR′3 is PPh3 and M is Pt, react further to give R-C≡P and cis-X2Pt(PPh3)2. In polar solvents (CH2Cl2 and CHCl3), all the addition products (I and II) convert to R-C≡P and cis- or trans-X2M(PR′3)2 via the surprising phosphabicyclo intermediate (X)(PR′3)2Pt-(X-PBC) (III and IV); the structure of IIIa was established crystallographically. In the presence of H2O, (X)(PEt3)2Pt[C(=PR)X] (Ia and Ib where X = Cl, Br) give the oxophosphabicyclo complex (X)(PEt3)2Pt[(H)O=PBC] (Va and Vb) which was characterized by X-ray diffraction. A mechanism for the conversion of (X)(PR′3)2M[C(=PR)X] to R-C≡P and X2M-(PR′3)2 is proposed.
- Jun, Hyoung,Young Jr., Victor G.,Angelici, Robert J.
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p. 2444 - 2453
(2008/10/08)
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- Mechanism of the platinum-promoted conversion of Cl2C=PR to R-C≡P, where R = 2,4,6-tri-tert-butylphenyl
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The reaction of Cl2C=PR with Pt(PEt3)4 to give R-C≡P and Pt(PEt3)2Cl2 proceeds through intermediates II and III. An X-ray diffraction study shows that the 2,4,6- tri - tert- butylphenyl ring in III is no longer aromatic. However, the aromaticity is restored when migration of the R group from the P to C is completed in forming the R-C≡P product.
- Jun, Hyoung,Angelici, Robert J.
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p. 4265 - 4266
(2008/10/08)
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- Stability of (Chloromethyl)platinum(II) Complexes
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The stabilities of , (cod = cycloocta-1,5-diene) and a range of phosphine-containing mono- and cis-bis-(chloromethyl)platinum(II) complexes have been investigated in deuteriochloroform at room temperature.Some of the bis(chloromethyl) derivatives appear to be indefinitely stable (cod and chelating arylphosphines), others suffer very slow decomposition to the dichlorides (non-chelating arylphosphines), and the remainder decompose relatively rapidly, and cleanly, to the dichlorides plus ethylene (alkylphosphines, non-chelating faster than chelating).Rapid decomposition of the arylphosphine complexes can be induced by adding hexafluoroisopropyl alcohol to the deuteriochloroform solutions.Attempts to generate 2> by addition of P(C6H11)3 to resulted in the formation of cis--+(C6H11)3>Cl2>; a mechanism is proposed.All cis-mono(chloromethyl) derivatives studied appear to be indefinitely stable.In contrast, the trans-mono(chloromethyl) complexes, although stable in very dry solvent, undergo decomposition in the presence of moisture to the corresponding hydrides plus formaldehyde; a mechanism is proposed.The hydrides undergo subsequent conversion into a mixture of cis and trans dichlorides.
- McCrindle, Robert,Arsenault, Gilles J.,Gupta, Anuradha,Hampden-Smith, Mark J.,Rice, Richard E.,McAlees, Alan J.
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p. 949 - 954
(2007/10/02)
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- A Study of the Generality of the Reaction of Diazomethane with Halogenoplatinum(II) Complexes in the Preparation of (Halogenomethyl)platinum(II) Complexes
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Treatment of a range of platinum(II) halide (mainly chloride) complexes with diazomethane has been examined.Formation of both mono- and bis-halogenomethyl products has been observed.With one exception, methylene insertion appears to occur only when the metal-halogen bond is trans to a group of high trans influence (olefin, phosphine, isocyanide, alkyl, or hydride).With the trans-chlorohydrido derivatives investigated, the initially formed trans-(chloromethyl)hydrido products rearranged into the trans-(chloro)methyl species.Mechanisms of the methylene insertion and rearrangement processes are discussed.
- McCrindle, Robert,Arsenault, Gilles J.,Farwaha, Rejeev,Hampden-Smith, Mark J.,Rice, Richard E.,McAlees, Alan
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p. 1773 - 1780
(2007/10/02)
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- Reactions of coordinatively unsaturated platinum(II)-η1-allyl complexes with the electrophilic reagents sulfur dioxide, chlorosulfonyl isocyanate, and hexafluorophosphoric acid etherate
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New platinuma(II)-η1-allyl complexes of the type trans-(η1-C3H5)Pt(PR3) 2Cl (PR3 = PMe2Ph, P(i-Pr)3, P(t-Bu)3) have been synthesized by reaction of [(C3H5)PtCl]4 with 8 equiv of PR3. These and known complexes trans-(η1-C3H5)Pt(PR3) 2Cl (PR3 = PEt3, PCy3) and trans-(η1-CH2CH=CHMe)Pt(PEt3)2Cl have been investigated with respect to their behavior toward the electrophiles SO2, ClSO2NCO, and HPF6·Et2O. The complexes trans-(η1-C3H5)Pt(PR3) 2Cl react with SO2 in benzene solution at 25°C to afford trans-(CH2=CHCH2S(O)2)Pt(PR3) 2Cl, the order of reactivity as a function of PR3 being PEt3, PMe2Ph > P(i-Pr)3 > P(t-Bu)3 (no reaction). The crotyl isotopomers trans-(CH2CH=C*HMe)Pt(PEt3)2Cl (*H = H, D) insert SO2 with rearrangement of the η1-allyl fragment to give trans-(CH2=CHC*H(Me)S(O)2)Pt(PEt3) 2Cl. These sulfinato-S products were characterized by chemical analysis and IR and 1H and 31P{1H} NMR spectroscopy, and the structure of trans-(CH2=CHCH2S(O)2)Pt(PMe 2Ph)2Cl was determined by X-ray crystallography. Treatment of trans-(η1-C3H5)Pt(PR3) 2Cl (PR3 = PEt3, PCy3) and trans-(η1-CH2CH=CHMe)Pt(PEt3)2Cl with HPP6·Et2O in diethyl ether or toluene affords the η2-propene and η2-1-butene complexes [trans-(η2-CH2=CHMe)Pt(PR3) 2Cl]PF6 and [trans-(η2-CH2=CHEt)Pt(PEt3) 2Cl]PF6, respectively. The reactions with SO2 and HPF6·Et2O have been rationalized to proceed by attack of the electrophile at the allyl C=C; they appear to be analogous to the corresponding reactions of the 18-electron transition-metal-η1-allyl carbonyls and of related complexes. Treatment of trans-(η1-C3H5)Pt(PR3) 2Cl (PR3 = PEt3, P(i-Pr)3, PCy3) with ClSO2NCO in toluene at 25°C affords trans-Pt(PR3)2Cl2; in contrast, when these reactions are conducted at -78°C with gradual warming, trans-Pt(PR3)2Cl2 and/or another product, tentatively formulated as the cycloadduct trans-CH2N(SO2Cl)C(O)CH2CHPt(PR 3)2Cl, are obtained. The presumed cycloadduct could not be separated from trans-Pt(PR3)2Cl2 and was only characterized by 31P{1H} NMR spectroscopy and FAB mass spectrometry in the mixture. When L = PEt3, a precursor of trans-Pt(PEt3)2Cl2, possibly (η1-C3H5) Pt(PEt3)2Cl2(SO2NCO), is observed. The reactions with ClSO2NCO are provisionally explained by competing [3 + 2] cycloaddition and oxidative addition-reductive elimination pathways. Crystallographic data: monoclinic, space group P21/n, a = 10.633 (2) A?, b = 16.830 (4) A?, c = 13.745 (3) A?, β = 112.77 (2)°, Z = 4, R = 0.032, and Rw = 0.038.
- Hu, Yeh-Rom,Wojcicki, Andrew,Calligaris, Mario,Nardin, Giorgio
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p. 1561 - 1568
(2008/10/08)
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- Preparation and characterization of some mixed ligand complexes of platinum(II)
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The mixed ligand complexes PtX2(ER3)L and PtXY(ER3)L (where ER3 = PR3 or AsMe3; L = phosphine, arsine; X = Cl; Y = Cl, H or Me) have been prepared and characterized. Reaction of PtMe2(ER3)L with HCl yields PtMeCl(ER3)L, in exclusively one of three possible isomeric forms. Excess tetramethyltin reacts with Pt2Cl2(μ-Cl)2(PMe2Ph)2 giving both cis and trans Pt2(μ-Cl)2(PMe2Ph)2, as identified from the NMR spectra. Cleavage of Pt2(μ-Cl)2Me2(PMe2Ph)2 with donor ligands such as AsPh3, PMe2 or pyridine, was useful as a synthetic route to the unsymmetrical methylchloro PtII derivatives. The reaction of cis-[PtMe2(PPh3)(AsPh3)] with excess dimethylacetylenedicarboxylate (DMA) yielded only one product, which was of the formula trans-[Pt{C(COOCH3)C(COOCH3)CH3}2(PPh3)(AsPh3)], with the alkenyl groups having the same geometry about the CC bond. The use of diethylacetylene-dicarboxylate (DEA) rather than DMA gave a similar product. However, when cis-[PtMe2(PEt3)(AsPh3)] was allowed to react with DMA, two products of the formula trans-[Pt{C(COOCH3)C(COOCH3)CH3}2(PEt3)(AsPh3)] were obtained, with the stereochemistry of both alkenyl groups being either cis or trans.
- Clark, Howard C.,Goel, Anil B.,Jain, Vimal K.,Tyers, Kenneth G.,Wong, Chun S.
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p. 123 - 134
(2007/10/02)
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- The Mechanism of the Photochemical Production of Hydrogen from Aqueous Solutions of Hydridotris(triethylphosphine)platinum(II)
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The photolysis of aqueous solutions of + at pH 2-12 in the presence of SO2-4 with near-u.v. light produces hydrogen and 2+.In the presence of Cl-, hydrogen, +, and are obtained.Variations in the amount of added chloride lead to the rate expression d(H2)/dt = a->/(b + c->2) which can be accommodated by the formation of intermediates, + and , the latter being present as a 'tight' ion pair, if loss of hydrogen only occurs from the former.The first-order dependence on light intensity is taken as evidence that the platinum(IV) dihydrides are formed by protonation of the ground state of +.A similar mechanism operates in the presence of SO42- except that photochemical hydrogen production occurs more readily from 2+ than from .
- Bruce, Duncan W.,Cole-Hamilton, David J.,Pogorzelec, Peter
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p. 2941 - 2946
(2007/10/02)
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- OXIDATIVE DIMERISATION OF ARYLAMIDO COMPLEXES OF PLATINUM: X-RAY STRUCTURE OF PF6
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The phenyl groups of two molecules of the phenylamido complex are oxidatively coupled, in the para position, by AgPF6 to give the dicationic complex 2 which can be deprotonated to the paramagnetic monocationic complex PF6.This has been examined by X-ray crystallography (orthorombic, space group Pnnm, R = 0.024 for 2 854 diffractometer measured observed reflections).The structure shows a bridging benzidine group which is strictly planar with marked quinonoid character within the arene rings .The mononuclear p-tolyl complex undergoes a similar coupling in the ortho position, but the 1-naphthyl complex gives a neutral coupled complex beacause of the much reduced conjugation in the twisted 1,1'-binaphtyl system.
- O'Sullivan, Richard D.,Parkins, Adrian W.,Alcock, Nathaniel W.
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p. 571 - 576
(2007/10/02)
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- Reactions of Halogenohydridobis(triethylphosphine)platinum(II) with Trihalogenophosphines: Some Unusual Complexes of PtII containing Five-co-ordinated Phosphorus
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31P N.m.r. spectra show that reacts with PCl3 in CH2Cl2 at 180 K to give , (5), and the previously unknown , (4).On warming to 240 K, complex (5) decomposes and (4) is reversibly protonated to give PtCl(
- Allen, Christopher W.,Ebsworth, E. A. V.,Henderson, Steven G.,Rankin, David W. H.,Robertson, Heather E.,et al.
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p. 1333 - 1338
(2007/10/02)
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- Preparation and characterization of heterobimetallic halogen-bridged palladium-platinum complexes. Crystal and molecular structure of [(PEt3)CIPd(μ-Cl)2PtCl(PEt3)]
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Attempts to prepare and characterize unambiguously heterobimetallic complexes of the type [(PR3)ClPd(μ-Cl)2PtCl(PR3)](R = Et, n-Pr, Bu, Ph; PR3 = PMe2Ph) using infrared, 31P and 195Pt NMR, and mass spectroscopies are described. It is established that, in solution, an equilibrium exists between [(PR3)ClPd(μ-Cl)2PtCl(PR3)], [(PR3)2Pd2Cl4], and [(PR3)2Pt2Cl4], the latter two species always being in 1:1 molar ratio; this equilibrium is temperature independent but is influenced by excess of either one of the dimers [(PR3)2M2Cl4] (M = Pt, Pd). The reactions of the heterobimetallic products with SnCl2·2H2O have been investigated, as well as the bridge-cleavage reactions with various donor ligands, in order to elucidate the chemical behavior of the heterobimetallic dichloro bridge; neutral ligands appear to be distributed equally between Pd and Pt. Crystals of the reaction product, with a composition corresponding to [(PEt3)ClPd(μ-Cl)2PtCl(PEt3)] are monoclinic, space group P21/n, with a = 7.590 (2) A?, b = 12.216 (1) A?, c = 12.119 (1) A?, and β = 101.87 (1)° With Z = 2 the molecules must lie about inversion centers, and the Pd and Pt atoms are mutually disordered. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations with anisotropic thermal parameters; R = 0.030 and Rw = 0.033 for 2451 observed reflections. The unique metal atom has slightly distorted square planar geometry with M-P = 2.214 (1), M-Cl (terminal) = 2.275 (1), M-Cl (bridging trans to P) = 2.437 (1), and M-Cl (bridging trans to Cl) = 2.314 (1) A?. The data do not unambiguously identify the solid product but, in combination with the NMR and mass spectroscopic data, do establish conclusively the existence of these beterobimetallic complexes.
- Clark, Howard C.,Ferguson, George,Jain, Vimal K.,Parvez, Masood
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p. 1477 - 1482
(2008/10/08)
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- Photochemical generation of bis(phosphine)palladium and bis(phosphine)platinum equivalents
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Ultraviolet irradiation of oxalato bis(tertiary phosphine) complexes of platinum(II) and palladium(II), Pt(C2O4)L2 and Pd(C2O4)L2, results in the reductive elimination of the oxalate ligand
- Paonessa, Ralph S.,Prignano, Andrea L.,Trogler, William C.
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p. 647 - 657
(2008/10/08)
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- BOND ENERGIES AND THERMAL DECOMPOSITION OF 2> COMPLEXES
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The thermal decomposition of the complexes trans- (L = P(C2H5)3; X = Cl, Br, I, CN) in decalin at 170 and 200 deg affords methane, platinum metal and .The kinetics of the decomposition of the complexes were determined by monitoring the appearance of methane by GLC.The observed first-order rate constant was found to be independent on the nature of the ligand X.The thermal decomposition of the trideuteriomethyl complexes (X = I, CN) in decalin-d18 at 170 and 200 deg C was studied by GLC/MS.The thermolysis affords CD3H and CD4 in ratios which are independent of the nature of X and of the temperature used.The mass spectra of the complexes were also examined.A relative scale of platinum-to-methyl bond dissociation energies has been established by measuring the appearance potential of the fragment ion + and the ionization energies in the series .Ionization potentials and Pt-CH3 bond energies show a clear dependence on the nature of X which is not reflected in corresponding changes in the decomposition rates.
- Morvillo, A.,Favero, G.,Turco, A.
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p. 111 - 118
(2007/10/02)
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- Substitution and Isomerisation Reactions at Platinum(II) involving Halide, Tertiary Phosphine, Carbonyl, and Isonitrile Ligands
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Carbon monoxide catalyses trans to cis isomerisations of (L = tertiary phosphine) in chloroform solution.The process involves formation of five-co-ordinate intermediates from which halide or tertiary phosphine can be eliminated, giving trans-(1+) or cis- respectively.Structure changes appear to be by pseudo-rotations rather than by consecutive displacements.A number of isonitrile complexes undergo similar reactions.Halide-bridged cations (2+) formed by halide extraction from cis- by Ag(1+) enter rapid (n.m.r. time-scale) exchange processes with the latter complexes at ambient temperatures.Halide elimination from cis- by solvent chloroform appears to initiate the process.The trans isomers do not participate in the exchange.
- Cross, Ronald J.,Phillips, Ian G.
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p. 2261 - 2264
(2007/10/02)
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- Synthesis and Reactivity of Platinum-Formaldehyde Complexes
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Sodium dihydronaphthylide reduction of (R3=Et3, Pri3, Ph3, Et2Ph, or 1/2Ph2PCH2CH2PPh2) under an ethylene atmosphere gives in quantitative yield as shown by (31)P n.m.r. spectroscopy.Reactions of the ethylene complexes with CO, CH2I2, (CF3)2CO, (CO2Et)2CO, and CH2O are described.Monomeric formaldehyde reacts to give the first platinum-formaldehyde complexes, , decomposition of which produces (n=3 or 4) and a complex tentatively assigned as .
- Head, Robert A.
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p. 1637 - 1640
(2007/10/02)
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- Darstellung und Reaktionen von kationischen Chlorobis(phosphan)platin(II)-Komplexen
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+BF4- (1) and (R3P)2Pt(Cl)OSO2CF3 (2) have been prepared by abstraction of chloride from cis-(R3P)2PtCl2 using tetrafluoroboric acid or trifluoromethanesulfonic acid, respectively.The protons of the aqua ligand in 1 form hydrogen bridges to the BF4- anion.The acidic complexes 1 and 2 are useful starting materials for new platinum(II) complexes.HCO3- neutralizes 1 to form the carbonato complex (Et3P)2PtO2CO (5).The heterogenous reaction of 2a with glycinate gives the cationic chelate complex (6).The coordinated water of 1 is easily substituted by other ligands, e.g. phosphanes.The chloro-bridged complexes 2+ are formed by treatment of 1 or 2 with ethers.
- Olgemoeller, Bernhard,Olgemoeller, Luitgard,Beck, Wolfgang
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p. 2971 - 2978
(2007/10/02)
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- Some Reactions of Nitrosyl Complexes of Nickel, Palladium, and Platinum
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The reactions of n3, OPPh3, or NC5H5; X=Br, L=1/2 dppe or PPh3; X=NO2, L=1/2 dppe> and trans- (M=Pd, L=PEt2Ph or PEt2; M=Pt, L=PEt2Ph, PEt3, or P n-Bu3) with carbon monox
- Bhaduri, Sumit A.,Bratt, Ian,Johnson, Brian F. G.,Khair, Abul,Segal, John A.,et al.
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p. 234 - 239
(2007/10/02)
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- Direct Oxidative Addition-Reductive Elimination Reactions Between trans- and or trans- (M = Rh or Ir, L = tertiary phosphine)
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Complexes of the type trans- and .M = Rh or Ir, L = PMe2Ph or PEt2Ph, have been shown to react with each other, presumably by a double chloro-bridged intermediate, and undergo rapid oxidative addition-reductive elimination; phosphine exchange is much slower.Similar results were obtained when trans- was treated with trans-, M = Rh or Ir, for which rapid and complete conversion into trans- and occured. (31)P NMR data are given.
- Al-Jibori, Subhi,Crocker, Christopher,Shaw, Bernard L.
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p. 319 - 321
(2007/10/02)
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- Study of PtX2(PR3)2 in the presence of PR3 in CH2Cl2 solution and the cis-trans isomerization reaction as studied by 31P NMR. Crystal structure of [PtCl(PMe3)3]Cl
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The identity of the species present in dichloromethane solutions of PtX2L2 and L (L = PMe3, PEt3, P-n-Bu3, P(tol)3 where tol = p-tolyl; Pt:L ratios from 1:0.05 to 1:5) are cis- and trans-PtX2L2, [PtXL3]+ (X = Cl, Br), and [PtXL4]+ (X = Cl, Br, I; L = PMe3). The only species with three coordinated phosphines which is five-coordinate in solution is PtI2(PMe3)3, whose IR and NMR parameters are consistent with a square-pyramidal geometry having one phosphine in the apical position. All other tris complexes [PtXL3]+ are four-coordinate in solution as shown by UV and 31P NMR spectroscopy, and this geometry is also found in the solid state ([PtCl(PMe3)3]Cl X-ray crystal structure). The complexes [PtX(PMe3)4]+ have a square-pyramidal geometry with X in the apical position. In the case of L = PMe3,31P NMR studies show that intermolecular phosphine exchange occurs between [PtClL3]+, [PtClL4]+, PtI2L3, and free L, whose activation parameters, estimated from line-shape analysis, are reported. Contrary to previous reports, chloride ion is found to displace one phosphine from [PtClL3]+ ion, giving the cis-PtCl2L2 isomer in a fast step prior to cis-trans equilibration. The results indicate that the cis-trans isomerization of PtX2L2 catalyzed by L proceeds by rapid displacement of X- by L followed by slow displacement of L by X- and not by pseudorotation of a five-coordinate intermediate. A similar mechanism was established for the isomerization of the alkyl complex PtCl(CH2CN)(PPh3)2.
- Favez, Roland,Roulet, Raymond,Pinkerton, Alan A.,Schwarzenbach, Dieter
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p. 1356 - 1365
(2008/10/08)
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