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Complexes Trans (complex + trans)
Selected AbstractsCyanoimide-Bridged, Bi- and Trinuclear, Heterometallic Complexes with an NCN,Mo,NCN Phosphinic CoreEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2009Sónia M. P. R. M. Cunha Abstract The heterometallic dinuclear complexes of the types trans -[Mo(NCN)(dppe)2(,-NCN)M] [M = WCl4(PPh3), ReOCl3(PPh3) or mer -ReCl(N2)(PMePh2)3; dppe = Ph2PCH2CH2PPh2] and [Mo(NCN)(dppe)2(,-NCN)M][BF4]Br [M = trans -Fe(NCC6H4NO2 -4)(depe)2; depe = Et2PCH2CH2PEt2] and the trinuclear ones [Mo(dppe)2{(,-NCN)M}2] [M = VCl3(thf) or PtCl2(PEt3)] were prepared by reaction of the bis(cyanoimido)molybdenum complex trans -[Mo(NCN)2(dppe)2] with the corresponding transition-metal Lewis acid (M) precursors, particularly [VCl3(thf)3], [WCl4(PPh3)2], [ReOCl3(PPh3)2], trans -[ReCl(N2)(PMePh2)4], trans -[FeBr(NCC6H4NO2 -4)(depe)2][BF4] and [Pt2Cl4(PEt3)2]. These adducts were characterized by FTIR, 1H, 13C and 31P{1H} NMR spectroscopy, mass spectrometry and cyclic voltammetry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and Structural Characterisation of Palladium and Group-12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2006Abstract Diethyl [1,-(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1,-dibromoferrocene and studied as a ligand for palladium(II) and group-12 metals. Treatment of [PdCl2(cod)] (cod = ,2:,2 -cycloocta-1,5-diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride-bridged complex [{Pd(,-Cl)Cl(1 -,P2)}2] (2) and the mononuclear complex trans -[PdCl2(1 -,P2)2] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group-12 metal bromides MBr2 in a 1:1 molar ratio gave the adducts [MBr2(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O1,P2 -chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(,-Br)}2 units interconnected by pairs of O1,P2 -bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide-bridged dimer, [{Hg(,-Br)Br(1 -,P2)}2]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate-O1 atoms from adjacent molecules. An isomer to 6, [{HgBr2(1 -,2O1,P2)}2] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr2} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid-state structures of 1, 2·,H2O, 3·4,CHCl3, 4, 5, 6·5,C6H6, and 7 have been determined by single-crystal X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Reactions of K2[Fe(CO)3(PPh3)]: Reductive Sb,Sb Coupling with Ph2SbCl To Form trans -[Fe(CO)3(PPh3)(Sb2Ph4)] and Salt Metathesis with Me3SbCl2 To Yield trans -[Fe(CO)3(PPh3)(SbMe3)]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2005Ingo-Peter Lorenz Abstract In contrast to the ferrate K2[Fe(CO)4], the phosphane-substituted ferrate K2[Fe(CO)3(PPh3)] (1) reacts with the stibane derivative Ph2SbCl by metal-assisted reductive Sb,Sb coupling to give the distibane complex trans -[Fe(CO)3(PPh3)(Sb2Ph4)] (3). The distibane ligand in 3 is terminally ,1 -coordinated trans to the phosphane ligand. However, the stiborane derivative Me3SbCl2 reacts with 1 in a metathetical substitution reaction to form the monostibane complex trans -[Fe(CO)3(PPh3)(SbMe3)] (5). Both compounds have been characterized by spectroscopic (IR, NMR, MS), analytical (C, H) and X-ray diffraction analyses. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Donor-Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium-Catalyzed Alkynylation and Platinum-Catalyzed Hydrogenation in Ionic LiquidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Samer Saleh Abstract The straightforward synthesis of a new donor-stabilized phosphenium ligand 3d by addition of bromodifurylphosphine to 1,3-dimethylimidazolium-2-carboxylate 1 is described. The obtained ligand exhibits a very strong ,-acceptor character, comparable to that of triphenyl phosphite [P(OPh)3] or of tris-halogenophosphines, with a ,CO(A1) at 2087,cm,1 for its nickel tricarbonyl complex. This ligand, as well as the related 3a which was obtained from chlorodiphenylphosphine, were tested in palladium-catalyzed aryl alkynylation and in the platinum-catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionic liquid phase. In CC bond cross-coupling we observed that the increase of the ,-acceptor character in ligand 3d, due to the introduction of an additional electron-withdrawing group, provides a very efficient catalyst in the alkynylation reaction of aryl bromides with phenylacetylene, including the deactivated 4-bromoanisole or the sterically hindered 2-bromonaphthalene. The catalytic activity decreases with recycling due to the sensitiveness of ligands to protonation in the ionic phase. Conversely, a multiple recycling of the metal/ligand system in non-acidic media was achieved from platinum-catalyzed hydrogenation of m- chloronitrobenzene. The catalytic results obtained by employing the complex of platinum(II) chloride with 3a [trans -PtCl2(3a)2] in comparison with the non-ionic related trans -tris(triphenylphosphine)platinum dichloride [trans -PtCl2(PPh3)2] complex clearly indicate that the simultaneous existence of a strong ,-acceptor character and a positive charge within the ligand 3a significantly increases the life-time of the platinum catalyst. The selectivity of the reaction is also improved by decreasing the undesirable formation of dehalogenation products. This cationic platinum complex trans -PtCl2(3a)2 is the first example of a highly selective catalyst for hydrogenation of chloronitroarenes immobilized in an ionic liquid phase. The system was recycled six times without noticeable metal leaching in the organic phase, and no loss of activity. [source] A Photoactivated trans -Diammine Platinum Complex as Cytotoxic as CisplatinCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2006Fiona S. Mackay Abstract The synthesis and X-ray structure (as the tetrahydrate) of the platinum(IV) complex trans,trans,trans -[Pt(N3)2(OH)2(NH3)2] 3 are described and its photochemistry and photobiology are compared with those of the cis isomer cis,trans,cis -[Pt(N3)2(OH)2(NH3)2] 4. Complexes 4 and 3 are potential precursors of the anticancer drug cisplatin and its inactive trans isomer transplatin, respectively. The trans complex 3 is octahedral, contains almost linear azide ligands, and adopts a layer structure with extensive intermolecular hydrogen bonding. The intense azide-to-platinum(IV) charge-transfer band of complex 3 (285 nm; ,=19,500,M,1,cm,1) is more intense and bathochromically shifted relative to that of the cis isomer 4. In contrast to transplatin, complex 3 rapidly formed a platinum(II) bis(5,-guanosine monophosphate) (5,-GMP) adduct when irradiated with UVA light, and did not react in the dark. Complexes 3 and 4 were non-toxic to human skin cells (keratinocytes) in the dark, but were as cytotoxic as cisplatin on irradiation for a short time (50 min). Damage to the DNA of these cells was detected by using the "comet" assay. Both trans- and cis -diammine platinum(IV) diazide complexes therefore have potential as photochemotherapeutic agents. [source] Bis(acetylido) Complexes of Ruthenium(II) Bearing Monodentate Phosphane LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2008Leslie D. Field Abstract Terminal acetylenes react with cis -RuMe2(PMe3)4 to form the bis(acetylido) complexes cis/trans -Ru(C,CR)2(PMe3)4 in good yield. The structures of trans - 2 (R = Ph), cis - 3 (R = p -C6H4 -OMe), trans - 4 (R = p -C6H4 -Me), cis - 6 (R = Me), trans - 7 (R = SiMe3) and cis - 8 (R = H) were determined by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Platinum(IV) Complexes of 3- and 4-Picolinic Acids Containing Ammine or Isopropylamine Ligands , Synthesis, Characterization, X-ray Structures, and Evaluation of Their Cytotoxic Activity against Cancer Cell Lines,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008María J. Macazaga Abstract The preparation and characterization of the new complexes trans -[PtCl4(NH3)(3-picolinic acid)] (1), trans -[PtCl4{NH2CH(CH3)2}(3-picolinic acid)] (2), trans -[PtCl4(NH3)(4-picolinic acid)] (3), and trans -[PtCl4{NH2CH(CH3)2}(4-picolinic acid)] (4) are described. The main structural feature of these complexes is the presence of ligands capable of multiple hydrogen-bonding interactions. Crystals of 1, 2, 3, and 4 suitable for single-crystal X-ray diffraction were grown, and the molecular structures of these compounds are discussed. In contrast to the inactive parent PtII complexes, the PtIV complexes displayed cytotoxic activity against various cancer cell lines used at the National Cancer Institute (NCI) for in vitro screens. Once more, the isopropylamine derivatives showed the best cytotoxicity values. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Oxidative Addition of B,Br Bonds to Pd0: Synthesis and Structure of trans -Bromo(boryl)palladium ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008Holger Braunschweig Abstract The oxidative addition of several bromoboranes to the Pd0 species [Pd(PCy3)2] yielded the novel palladium boryl complexes trans -[(Cy3P)2Pd(Br)(BCat)] (1) (Cat = 1,2-dioxophenylene), trans -[(Cy3P)2Pd(Br)(BCat,)] (2) (Cat, = Cat-4- tBu) and trans -[(Cy3P)2Pd(Br){B(X)X,}] {X = Br, X, = NMe2 (3), Pip (4) (Pip = NC5H10), Mes (5) [Mes = 2,4,6-(CH3)3C6H2]}. Compounds 1,5 were characterized by multinuclear NMR spectroscopy in solution; single crystals for X-ray analyses were acquired from 2 and 3, which thus allowed comparison of the structural data. The few palladium boryl complexes published so far were obtained by ,-bond metathesis; the oxidative addition of the corresponding bromoboranes to Pd0 has not yet been reported.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of (1,2,4-Oxadiazole)palladium(II) Complexes by [2 + 3] Cycloaddition of Nitrile Oxides to Organonitriles in the Presence of PdCl2EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2005Nadezhda A. Bokach Abstract The reaction between the nitrile oxides 2,4,6-R3C6H2CNO (R = Me, OMe) and trans -[PdCl2(RCN)2], or RCN (R = Me, Et, CH2CN, NMe2, Ph) in the presence of PdCl2, proceeded smoothly under mild conditions and allowed the isolation of the 1,2,4-oxadiazole complexes trans -[PdCl2{Na=C(R)-ON=Cb(C6H2R3)(Na,Cb)}2] (1,8) in 40,85,% yields. In CH2Cl2, the reaction between 2,4,6-R3C6H2CNO and [PdCl2(MeCN)2] furnishes [PdCl2(ONCC6H2R3)2] (9 and 10), which are the first representatives of metal compounds where nitrile oxides act as ligands. The 1,2,4-oxadiazole complexes 1,8 were characterized by elemental analysis, FAB mass spectrometry, and IR, 1H and 13C{1H} NMR spectroscopy, while 2, 3, 7, and 8 were additionally characterized by X-ray crystallography. The liberation of the heterocyclic species from 1,8 was successfully performed by substitution reaction either with 1,2-bis(diphenylphosphanyl)ethane or with an excess amount of Na2S·7H2O in MeOH; the liberated 1,2,4-oxadiazoles (11,18) were characterized by positive-ion FAB mass spectrometry and 1H and 13C{1H} NMR spectroscopy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Bis(fluoromesityl) Palladium Complexes, Archetypes of Steric Crowding and Axial Protection by ortho Effect , Evidence for Dissociative Substitution Processes , Observation of 19F,19F Through-Space CouplingsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2004Camino Bartolomé Abstract Bisarylated complexes trans -[Pd(Fmes)2(SR2)2] [Fmes = 2,4,6-tris(trifluoromethyl)phenyl (fluoromesityl); SR2 = SMe2, tht; tht = tetrahydrothiophene] are precursors for various bisarylated fluoromesityl palladium(II) complexes by ligand-substitution reactions. Boiling under reflux in acetonitrile gives the mixed complexes trans -[Pd(Fmes)2(NCMe)(SR2)], whereas boiling under reflux in toluene leads to trans -[PdCl2L2] (L = PMe3, tBuNC, pTol-NC, 4-MePy), in the presence of neutral monodentate ligands, or to (NnBu4)[trans -Pd(Fmes)2I(SR2)] when treated with (NnBu4)I. trans -[Pd(Fmes)2(SMe2)2] reacts with bidentate ligands, also boiling under reflux in toluene, to give [Pd(Fmes)2(L,L)] [L,L = Me2bipy, 2,2, - biquinolyl, ,2N,N, -OCPy2, dppm (Ph2PCH2PPh2), dppe (Ph2PCH2CH2PPh2), pte (PhSCH2CH2SPh), ,2S,N -SPPh2Py, ,2O,N -OPPhPy2], or the bimetallic complex [Pd(Fmes)2(,-1,N:1,2,O:2,N -Py2MeCO)Pd(Fmes)(SMe2)] (characterized by X-ray diffractometry) when treated with (OH)(CH3)CPy2. The crowding associated with two Fmes groups produces several interesting features: (1) trans complexes are preferred over cis complexes, against the expected electronic preferences; (2) the low-temperature NMR spectra of several complexes, or the X-ray diffraction structure of [Pd(Fmes)2(2,2, - biquinolyl)], reveal significant structural distortions associated with steric crowding; (3) the need for boiling under reflux in the synthesis suggests a dissociative substitution mechanism, which is unknown so far for Pd; (4) some of the complexes show 19F,19F through-space couplings. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Dynamic Features of (Chloro)zirconocene Cations Stabilised by Pendant (Diarylphosphanyl)alkyl and (Dimethylamino)alkyl Substituents at Their Cyclopentadienyl Ring SystemsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2003Steve Döring Abstract Treatment of the substituted (diarylphosphanyl)methyl group-4 metallocene complexes [(C5H4,CR1R2,PAr2)2ZrCl2] (2: R1/R2 = CH3/CH3, H/CH3, H/aryl) with Li[B(C6F5)4] in dichloromethane solution results in chloride ligand abstraction (with LiCl precipitation) to yield the complexes [(C5H4,CR1R2,PAr2)2Zr,Cl+] (5), with both phosphanyl groups internally coordinated to the metal centre. Three possible diastereoisomers are observed in the case of 5c (R1 = H; R2 = CH3), while bulkier R2 substituents give higher selectivities. The thermally induced (reversible) cleavage of the Zr,phosphane linkage results in dynamic NMR behaviour. Gibbs activation energies of ,G,(298 K) = 14.8 ± 0.5 and 14.5 ± 0.5 kcal/mol were obtained for these intramolecular equilibration processes in the complexes trans - 5d (R1 = H; R2 = Ph) and trans - 5e (R1 = H; R2 = ferrocenyl), respectively. Treatment of the substituted (dimethylamino)methyl metallocene complexes [(C5H4,CR1R2,NMe2)2ZrCl2] (6a, 6b) with Li[B(C6F5)4] proceeds analogously to yield the cation systems [{C5H4,C(CH3)2,NMe2}2ZrCl+] (12a) and [{C5H4,CH(CH3),NMe2}2ZrCl+] (12b, three possible diastereoisomers). Both complexes have their pairs of amino groups coordinated to the metal centre. The complexes exhibit dynamic NMR spectra. Selective equilibration of the diastereotopic N(CH3)A(CH3)B resonances of complex 12a is observed [,G,(233 K) = 11.5 ± 0.2 kcal/mol], whereas the adjacent C(CH3)A(CH3)B methyl groups remain diastereotopic. The dynamic equilibration of the latter was observed at a markedly higher temperature [,G,(333 K) = 17.3 ± 0.2 kcal/mol]. Treatment of [{C5H4,C(CH3)2,NMe2}CpZrCl2] (10) with Li[B(C6F5)4] resulted in the formation of complex [{C5H4,C(CH3)2,NMe2}CpZr,Cl+] (11), which shows the internal ,N(CH3)A(CH)B equilibration proceeding with a markedly higher activation barrier [,G,(333 K) = 17.6 ± 0.2 kcal/mol] than in 12a, and a stereochemical memory effect indicative of solvent coordination to the metal centre of the resulting highly electrophilic chlorozirconocene cation intermediate. Complex 11 was characterised by an X-ray crystal structure analysis, which shows the internal Zr,amine coordination. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Formation of (,-Alkenyl)- and (,-Vinylidene)palladium and -platinum Complexes by Oxidative Addition of 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene , The Molecular Structure of an Unusual Asymmetric (,-Vinylidene)Pd,Pd ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003Michael Knorr Abstract 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene (1) oxidatively adds to [Pd(PPh3)4] and [Pt(C2H4)(PPh3)2] giving rise to the ,-alkenyl complexes trans -[MCl{[C(Cl)=C(H),N=CPh2]}(PPh3)2] (2a: M = Pd; 2b: M = Pt). When 1 is treated with [Pd(PPh3)4] in a 1:2 ratio in refluxing toluene, the dimetallic ,-vinylidene complex [(PPh3)ClPd{,-[C=C(H),N=CPh2]}PdCl(PPh3)2] (3) is formed. In this fluxional compound, a PPh3 ligands migrates in a reversible manner between the two Pd centers. Substitution of the PPh3 ligands of 3 by 2 equiv. of Ph2PCH2PPh2 affords the A-frame complex [ClPd(,-dppm)2{,-[C=C(H),N=CPh2]}PdCl] (4). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Structural and Nonlinear Optical Properties of Aligned Heterotrinuclear [RuII -(Spacer)-MII -(Spacer)-RuII] Complexes (M=Pd, Pt; spacer=4-ethynylpyridine)CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2009Qingchun Ge Abstract Optical alloy: "Linear" heterotrinuclear assemblies, with the metals separated by 4-ethynylpyridine spacers [RuCp(CCpy-4)(dppf)]2[MCl2] (M=Pd, Pt), have been structurally identified. They are electrochemically active and show good cubic nonlinear optical responses. Lewis addition between the metalloligand [RuCp(CCpy-4)(dppf)] (1) (dppf=(C5H4PPh2)2Fe) and MCl2(CH3CN)2 gives [RuCp(CCpy-4)(dppf)]2[MCl2] (M=Pd (2) and Pt (3)), all of which have been spectroscopically and crystallographically characterized. The mixed-metal adducts show the d6 -d8 -d6 metal alignment maintained by the trans disposition of the directionally rigid 4-ethynylpyridine at the centrosymmetric square-planar metal center. Electrochemical studies of these and the related known complexes trans -[RuCl(CCpy-4)(dppm)2] (4) and [trans -RuCl(CCpy-4)(dppm)2]2[MCl2] (dppm=Ph2PCH2PPh2) (M=Pd (5) and Pt (6)) suggest that the spacer-linked heterotrinuclear network is able to stabilize the oxidized RuIII better than the metalloligand precursor. Cubic nonlinear optical responses are also generally higher for the heterometallic complexes. The ,real value of the PdRu2 dppm complex 5 is among the largest for linear organometallic complexes. [source] | ||||||||||