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OTf
Selected AbstractsLinear Coinage Metal Complexes Stabilized by a Group 13 Metalloid LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 28 2010Ganesan Prabusankar Abstract The synthesis and structural characterization of the linear, cationic complex [{(DDP)Ga}2Cu][OTf]·2C6H5F (2, Tf = O2SCF3) stabilized by the monodentate, gallium-based ligand Ga(DDP) (DDP = [HC{(CMe)N(2,6- iPr2C6H3)}2],), as well as NMR spectroscopic evidence for the formation of the corresponding silver compound [{(DDP)Ga}2Ag][Al(hfip)4] (3, hfip = [OC(H)(CF3)2]), are reported. The remarkable steric properties of this gallium-based ligand permit the stabilization of 2, which exhibits an unusual linear geometry and a coordination number of two. [source] Synthesis and Characterization of Linear Tetranuclear Silver(I) Complexes Bridged by Tetraphosphane LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 32 2009Yukie Takemura Abstract Reactions of AgOTf with meso -bis[(diphenylphosphanylmethyl)phenylphosphanyl]methane (dpmppm) afforded[Ag4(OTf)2(,-OTf)(,-dpmppm)2{(CH3)2CO}](OTf) (1) and [Ag4(OTf)2(,-OTf)(,-dpmppm)2(RNC)2](OTf) {R = Xyl (2a), Mes (2b), tBu (2c)}. When AgOTf was treated with dpmppm in air in the presence of tBuNC, cleavage of the C,Cl and P,C bonds occurred to give [Ag4(,-Cl)(,-dpmppm)2(tBuNC)4](OTf)3 (3) and [Ag4(,-Ph2PO2)(,-dpmppm)2(tBuNC)3](OTf)3 (4). Reaction of AgOCOCF3 with dpmppm resulted in [Ag4(OCOCF3)2(,-OCOCF3)(,-dpmppm)2](CF3COO) (5). By treatment of AgPF6 with dpmppm, [Ag4(,-dpmppm)2(tBuNC)4](PF6)4 (6) and [Ag4(PO2F2)2(,-dpmppm)2(tBuNC)2] (PF6)2 (7) were obtained. Wheareas complexes 1,3 possess a {Ag4(,-dpmppm)2}4+ core in which the Ag4 strings are rather bent with two dpmppm ligands arranged in a syn fashion, complexes 4,7 have linear Ag4 strings supported by two dpmppm ligands arranged in an anti fashion. These results suggest that the dpmppm-supported tetrasilver(I) strings are quite flexible and labile and thus are potentially important in promoting organic reactions as a result of the multimetallic centers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] An Unusual Anion,, Interaction in an ;rido Organometallic Assembly: Synthesis, First Crystal Structure, and Computational StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2009Jamal Moussa Abstract The organometallic assembly [Cp*Ir(,6 -C6H2O4)(BF2)2(CF3SO3)][Cp*Ir(,-Cl)3IrCp*] (3) was prepared from [Cp*Ir(solvent)3][OTf]2 (2) and 1,2,4,5 tetrahydroxybenzene (THB, 1) in acetone, in the presence of an excess amount of BF3·2H2O. Assembly 3 was fully characterized by multinuclear NMR spectroscopy. Remarkably, the X-ray molecular structure of 3 shows that an anion,, interaction occurs between the neutral component Cp*Ir(,6 -C6H2O4)(BF2)2 of the assembly and the CF3SO3 anion of the cationic species [Cp*Ir(,-Cl)3IrCp*]. Computational analysis was carried out on 3 to unravel the nature of this noncovalent interaction. Such an example could serve as a model to explain the important role of anions in organometallic chemistry and asymmetric catalysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Selective B,H versus N,H Bond Activation in Ammonia Borane by [Ir(dppm)2]OTf,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2009Andrea Rossin Abstract Ammonia borane (AB, NH3·BH3) was activated selectively on the boron hydrogen atoms by [Ir(dppm)2]OTf, as shown by variable-temperature 31P, 11B and 1H NMR studies, to yield cis - and trans -[Ir(H)2(dppm)2]OTf dihydrides. X-ray crystal structures of these complexes were obtained. DFT calculations suggest the key reaction intermediate to be a Lewis base (L) stabilised adduct, cis -[Ir(H)(BH2·L)(dppm)2]+(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The Variable Binding Modes of Phenylbis(pyrid-2-ylmethyl)phosphane and Bis(pyrid-2-ylmethyl) Phenylphosphonite with AgI and CuIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2009Fernando Hung-Low Abstract A series of new bridging phosphane and phosphonite structures forming three- and six-membered rings with the metal centers were synthesized and characterized. The resulting compounds of phenylbis(pyrid-2-ylmethyl)phosphane (1) with the silver(I) salts of trifluoroacetate (tfa,), tetrafluoroborate (BF4,), and trifluoromethanesulfonate (OTf,), and copper tetrakis(acetonitrile) hexafluorophosphate (PF6,) shows the flexibility of the ligand by displaying different coordination modes associated with the electronic and structural characteristics of the corresponding anion. Accordingly, ligand 1 in these complexes displays two different binding modes. With Agtfa and AgBF4 compounds 3 and 4 are obtained where the ligand chelates to two silver atoms that exhibit normalAg,Ag contacts in the range of 2.9 Å. When AgOTf or Cu(NCCH3)4PF6 are used, one molecule of 1 bridges the metal centers through a phosphorus atom while another is terminally bound. This induces short M,M distances of 2.6871 and 2.568 Å for 5 and 6, respectively. Similarly, the coordination behavior of the heterofunctional bis(pyrid-2-ylmethyl) phenylphosphonite ligand (2) is reported with Cu(NCCH3)4PF6 (7) and AgBF4 (8) to form two novel discrete molecules. In these complexes 2 coordinates through the P and N atoms, with the difference that in 7 the O atom of one of the carbinol arms is also bound to the Cu. Elemental analysis, variable-temperature multinuclear NMR spectroscopy, single-crystal X-ray diffraction, and low-temperature luminescence studies were carried out to fully characterize the compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Ruthenium ,6 -Hexamethylbenzene Complexes Containing Dichalcogenoimidodiphosphinate LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2009Wai-Man Cheung Abstract Treatment of [Ru(,6 -C6Me6)Cl2]2 with AgOTf (OTf, = triflato) followed by K[N(R2PQ)2] gave the 16-electron complexes [Ru(,6 -C6Me6){,2 -N(R2PQ)2}][OTf] [Q = S, R = Ph (1) or iPr (2); Q = Se, R = Ph (3) or iPr (4)] which were isolated as air-stable blue or dark green crystals. For complex 1, when the crude product was recrystallised from CH2Cl2/hexane in air, orange crystals of [Ru(,6 -C6Me6){,3 -N(Ph2PS)2}][OTf] (1a) were isolated as a minor product. The reaction of compound 1 with ammonia, hydrazine hydrate and 4,4,-bipyridyl(4,4,-bpy) gave the 18-electron adducts [Ru(,6 -C6Me6){,2 -N(Ph2PS)2}L][OTf] [L = NH3 (5), N2H4 (6)] and dinuclear[{Ru(,6 -C6Me6)[,2 -N(Ph2PS)2]}2(,-4,4,-bpy)][OTf]2 (7), respectively. Treatment of compound 2 with Li[BEt3H] and NaBH4 afforded the ethyl [Ru(,6 -C6Me6){N(iPr2PS)2}Et] (8) andhydride [Ru(,6 -C6Me6){,2 -N(iPr2PS)2}H] (9) compounds, respectively. Formal potentials for Ru[N(R2PQ)2] complexes have been determined. The structures for complexes 1, 1a, 5, 6, 8 and 9 have been established by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and Reactivity of Oxametallacyclic Niobium Compounds by Using ,,,-Unsaturated Carbonyl Ligands,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2008Rocío A. Arteaga-Müller Abstract Reduction of mono(cyclopentadienyl)niobium complexes [NbCpRCl4] [CpR = C5Me4H (1), C5H4SiMe2Cl (2), C5H4SiMe3 (3)] with Na/Hg in the presence of methyl methacrylate [MMA, CH2=C(Me)C(O)OMe (a)], methyl acrylate [MA, CH2=CHC(O)OMe (b)] and mesityl oxide [MO, CMe2=CHC(O)Me (c)] afforded the corresponding derivatives [NbCpRCl2(LL)] [CpR = C5Me4H, LL = MMA (1a); CpR = C5H4SiMe2Cl, LL = MMA (2a), MA (2b), MO (2c); CpR = C5H4SiMe3, LL = MMA (3a), MA (3b)] in variable yields depending on both the cyclopentadienyl and the ,,,-unsaturated carbonyl compounds. The reactivity of these complexes was studied toward protic and Lewis acids. Addition of triflic acid TfOH (Tf = CF3SO2) to 3b gave the triflate complex [NbCpRCl2{(CH2)2C(O)OMe}(OTf)] [CpR = C5H4SiMe3 (4)]. The Lewis acids E(C6F5)3 (E = B, Al) reacted with complexes 2b and 3b to give the three-membered metallacyclic (or ,2 -enone) compounds [NbCpRCl2{,2 -CH2=CHC(OMe){O·E(C6F5)3}}] [CpR = C5H4SiMe2Cl, E = B (5), Al (6); CpR = C5H4SiMe3, E = B (7), Al (8)], which decomposed to the corresponding adducts MA·E(C6F5)3. The same reaction with the 2a and 3a derivatives only allowed the observation of the corresponding adducts MMA·E(C6F5)3. Complexes 2a,b and 3a,b reacted with CO with elimination of the acrylate compounds, MA and MMA, respectively, to give the carbonylniobium(III) compounds [NbCpRCl2(CO)2]2 [CpR = C5H4SiMe2Cl (9), C5H4SiMe3 (10)]. Analogous reactions with CNAr showed the elimination of the free MA and MMA compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Urs Fischbach Abstract The tetradendate phosphane tris(5H -dibenzo[a,d]cyclohepten-5-yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5-chloro-5H -dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X-ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky ,1 -phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (, = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M,C=Ctrop) and ,(31P) decreases with increasing M,C=Ctrop in the order 9 (, = 260 ppm) > 7 (, = 196 ppm) > 6 (, = 135 ppm) > 3 (, = ,30.9 ppm). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Reaction of 1,3,5-Triazacyclohexanes with TiCl4: Formation of Cationic ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2005Randolf D. Köhn Abstract N -substituted 1,3,5-triazacyclohexanes [R3TAC; R = cyclohexyl, p -fluorobenzyl or Ph(CH2)n (n = 1, 2, 3)] react with excess TiCl4 to give the corresponding cationic ,3 complexes [(R3TAC)TiCl3][Ti2Cl9]. Attempts to prepare complexes with titanium-free anions at lower Ti:R3TAC ratio or with added Me3SiOTf lead to the same cations with [Ti2Cl10]2, and [Ti2Cl8(OTf)], anions. Five complexes as well as (p -fluorobenzyl)3TAC have been characterised by X-ray crystallography. The ring C,H bonds engage in hydrogen bonding interactions in the crystals and strongly solvent and anion dependent 1H NMR signals are detected in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Variability in the Structures of Luminescent [2-(Aminomethyl)pyridine]silver(I) Complexes: Effect of Ligand Ratio, Anion, Hydrogen Bonding, and ,-StackingEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2005Rodney P. Feazell Abstract The reaction of 2-(aminomethyl)pyridine (2-amp) with silver(I) salts of triflate (OTf,), trifluoroacetate (tfa,), and tetrafluoroborate (BF4,) produce monomeric, dimeric, bridged, and polymeric structural motifs. The structural characteristics are dependent upon the ratio of ligand/metal in the structure as well as the ability of the anion to coordinate to the metal centers and form hydrogen bonds to the bound ligands. The silver coordination environment takes on several geometries including near linear (6), trigonal (4), tetrahedral (1), and both trigonal-bipyramidal and square-based pyramidal in a single structure (2). Structures 2, 3, and 5 also display short Ag,Ag contacts ranging from 2.8958(3) to 3.0305(4) Å. The species with metal,metal interactions, which are connectively very similar to their metal-isolated counterparts of 1, 4, and 6, are held together only by weak ,-stacking interactions or hydrogen bonds to their respective anions. Low-temperature luminescence spectra were collected for all compounds and are compared. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Mono- and Dimetallic Cyano Complexes with {Mo(,3 -allyl)(CO)2(N,N)} FragmentsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2003Julio Pérez Abstract Treatment of [MoCl(,3 -allyl)(CO)2(phen)] with NaCN in CH2Cl2/MeOH afforded [Mo(CN)(,3 -allyl)(CO)2(phen)] [allyl = C3H5 (1a); 2-MeC3H4 (1b)] as the sole products (no products of cyanide attack on the allyl group were detected). Treatment of 1a,b with [Mo(OTf)(,3 -C3H5)(CO)2(phen)] and NaBAr,4 in CH2Cl2 yielded the compounds [{Mo(,3allyl)(CO)2(phen)}(,-CN){Mo(,3 -C3H5)(CO)2(phen)}]BAr,4 (2a,b). Analogous treatment of 1a with fac -[M(OTf)(CO)3(bipy)] (M = Mn, Re) and NaBAr,4 resulted in the synthesis of [{Mo(,3 -C3H5)(CO)2(phen)}(,-CN){M(CO)3(bipy)}]BAr,4 (3, 4), in which the C and N atoms of the cyano bridge are bonded to Mo and M (M = Mn, Re), respectively. The linkage isomer of 4 (C and N atoms of the cyano group bonded to Re and Mo, respectively) (6) was prepared by treatment of [Re(CN)(CO)3(bipy)] (5) with [Mo(OTf)(,3 -C3H5)(CO)2(phen)] and NaBAr,4. Compounds 1a, 2b, 3, and 6 were characterized by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Theoretical Study on Hetero-Diels,Alder Reaction of Butadiene with Benzaldehyde Catalyzed by Chiral InIII ComplexesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2010Xiuli Cao Abstract The mechanism of the hetero-Diels,Alder reaction of butadiene with benzaldehyde catalyzed by chiral N,N, -dioxide/In(OTf)3 complexes was studied theoretically by using density functional theory (DFT) and model system. The computational results indicate that the catalyzed reaction proceeded through a concerted mechanism via a highly zwitterionic transition state. The lowest energy barrier was 11.8 kJ,mol,1, which is 63.0 kJ,mol,1 lower than that of the uncatalyzed reaction. The results indicate that the endo approach is advantageous over the exo approach, because exo transitions states suffer from more steric hindrance than the endo transitions states as a result of interactions among the substrates, the trifluoromethanesulfonic group and the R4 groups of the ligand. The (S) configuration was observed predominantly over the (R) form, because there is no distinguishable repulsion between butadiene and the exo amino side or the endo amino side of the ligand. Besides, the interactions between the terminal hydrogen atoms of butadiene and the oxygen atoms of the trifluoromethanesulfonic group make the structure more stable. Thus, the experimental results were explained well by calculation of the chiral N,N, -dioxide/In(OTf)3 complex catalyzed hetero-Diels,Alder reaction at the molecular level. [source] Nd(OTf)3 -Catalyzed Cascade Reactions of Vinylidenecyclopropanes with Enynol: A New Method for the Construction of the 5,7,6 Tricyclic Framework and Its Scope and LimitationsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2009Liang-Feng Yao Abstract We report in this paper a Lewis acid [Nd(OTf)3]-catalyzed protocol to construct compounds containing a 5,7,6 tricyclic framework in good yield from readily accessible starting materials vinylidenecyclopropanes (VDCPs) 1 and enynols 2a,c under mild conditions. Upon examination of the scope and limitations of this reaction, it was found that the corresponding highly functionalized cyclopentane derivatives could be formed in good yields from the reaction VDCPs 1 and enol 2e or dienol 2c under identical conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Preparation of Triaryl- and Triheteroarylmethanes under Ytterbium Triflate Catalysis and Solvent-Free ConditionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2009Salvatore Genovese Abstract Triaryl- and triheteroarylmethanes have been synthesized in very good yield under solvent-free conditions from differently substituted aldehydes and 2-methylfuran or methoxybenzene in the presence of Yb(OTf)3 as catalyst. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Divalent Samarium Triflate Mediated Stereoselective Pinacol Coupling of Planar Chiral Phosphanyl and Phosphoryl FerrocenecarbaldehydeEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2009Shin-ichi Fukuzawa Abstract The pinacol coupling reaction of (Rp)-2-diphenylphosphanyl ferrocenecarbaldehyde (1) was smoothly mediated by divalent samarium triflate to give (R,R)-diol 2a predominantly, whereas the use of samarium(II) iodide resulted in low selectivity as described in the previous literature. In contrast, the coupling reaction of (Rp)-2-diphenylphosphoryl ferrocenecarbaldehyde (3) with Sm(OTf)2 gave the (S,S)-diol as the major isomer, which was the opposite stereochemistry of that obtained in the reaction with 1. The rhodium complexes of diphosphanes 2a were good catalysts for the asymmetric hydrogenation of ,-acetamidocinnamic acid, and the product was obtained quantitatively with up to 92,%,ee. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Bismuth Triflate Catalyzed Allylation of Aldehydes with Allylstannane under Microwave Assistance,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2007Thierry Ollevier Abstract In the presence of a catalytic amount of bismuth triflate and under microwave irradiation, mixtures of aldehyde and allylstannane afforded smoothly the corresponding homoallylic alcohol. A wide variety of aldehydes were treated under these conditions. The reactions proceeded rapidly and afforded smoothly the corresponding homoallylic alcohol in good to very good yields using catalytic amounts of Bi(OTf)3·4H2O (0.5 mol-%) and under microwave irradiation for a short time.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Novel Catalytic Tandem Isomerisation/Cyclisation Reaction of ,-Methallyloxy Carboxylic AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2006Xavier Chaminade Abstract A new tandem isomerisation/cyclisation of ,-methallyloxy carboxylic acids leading to substituted 1,3-dioxolan-4-ones in 60,70,% yields was catalysed by Cu(OTf)2 or Al(OTf)3. Extension to the synthesis of oxathiolanones and oxathianones is also described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Mild Synthesis of ,-Amino-,,,-difluoro Ketones from Acylsilanes and Trifluoromethyltrimethylsilane in a One-Pot Imino Aldol Reaction,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005Sylvain Jonet Abstract ,-Amino-,,,-difluoro ketones have been very conveniently prepared in a one-pot procedure from acylsilanes, trifluoromethyltrimethylsilane and imines. The key intermediate in this reaction is a difluoroenoxysilane. The Lewis acid promoted imino aldol reaction was performed with BF3·OEt2 or under very mild conditions using a catalytic amount of Yb(OTf)3. The reaction with chiral benzylimines occurred in good yield with 52,78,% de. Palladium-catalyzed hydrogenolysis furnished an unprotected ,-amino-,,,-difluoro ketone or a ,-amino-,,,-difluoro alcohol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Ring-Expansion of MCPs in the Presence of DIAD or DEAD and Lewis AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2004Li-Xiong Shao Abstract Treatment of methylenecyclopropanes (MCPs) with DIAD or DEAD in MeCN under mild conditions in the presence of Lewis acid Zr(OTf)4 gave the cyclobutanone ring-expansion products in good to high yields based on the employed DIAD or DEAD. From a deuterium labeling experiment, the oxygen atom is derived from ambient water. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Water Stability and Luminescence of Lanthanide Complexes of Tripodal Ligands Derived from 1,4,7-Triazacyclononane: Pyridinecarboxamide versus Pyridinecarboxylate DonorsHELVETICA CHIMICA ACTA, Issue 11 2009Grégory Nocton Abstract A series of europium(III) and terbium(III) complexes of three 1,4,7-triazacyclononane-based pyridine containing ligands were synthesized. The three ligands differ from each other in the substitution of the pyridine pendant arm, namely they have a carboxylic acid, an ethylamide, or an ethyl ester substituent, i.e., these ligands are 6,6,,6,-[1,4,7-triazacyclononane-1,4,7-triyltris(methylene)]tris[pyridine-2-carboxylic acid] (H3tpatcn), -tris[pyridine-2-carboxamide] (tpatcnam), and -tris[pyridine-2-carboxylic acid] triethyl ester (tpatcnes) respectively. The quantum yields of both the europium(III) and terbium(III) emission, upon ligand excitation, were highly dependent upon ligand substitution, with a ca. 50-fold decrease for the carboxamide derivative in comparison to the picolinic acid (=pyridine-2-carboxylic acid) based ligand. Detailed analysis of the radiative rate constants and the energy of the triplet states for the three ligand systems revealed a less efficient energy transfer for the carboxamide-based systems. The stability of the three ligand systems in H2O was investigated. Although hydrolysis of the ethyl ester occurred in H2O for the [Ln(tpatcnes)](OTf)3 complexes, the tripositive [Ln(tpatcnam)](OTf)3 complexes and the neutral [Ln(tpatcn)] complexes showed high stability in H2O which makes them suitable for application in biological media. The [Tb(tpatcn)] complex formed easily in H2O and was thermodynamically stable at physiological pH (pTb 14.9), whereas the [Ln(tpatcnam)](OTf)3 complexes showed a very high kinetic stability in H2O, and once prepared in organic solvents, remained undissociated in H2O. [source] Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusable zirconyl triflate, ZrO(OTf)2HETEROATOM CHEMISTRY, Issue 3 2009Majid Moghadam Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf)2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:131,135, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20523 [source] Bismuth-catalyzed cyclization of amino-1,6-enynesHETEROATOM CHEMISTRY, Issue 6 2008Kimihiro Komeyama Bi(OTf)3 effectively catalyzed the cyclization of amino-1,6-enynes, leading to bicyclic amine and cyclopentadienyl amino compounds. The selectivity of the products depends on the substitution pattern of the olefinic moiety. 19F NMR trace experiment of the reaction and other results indicate a novel alkynophilicity of the bismuth species. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:644,648, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20490 [source] Efficient Platinum(II) Catalyzed Hydroformylation Reaction in Water: Unusual Product Distribution in Micellar MediaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Marina Gottardo Abstract The hydroformylation of a variety of terminal and internal alkenes is efficiently performed by cationic platinum triflate complexes of the type [P2Pt(H2O)2](OTf)2 under mild conditions in an aqueous micellar medium. The use of surfactants is essential to ensure dissolution of the catalyst and substrate in water with catalysts being positioned on the anionic surface of the micelles. Aldehydes are obtained with linear to branched ratios up to >99:1. With styrene derivatives also the corresponding benzaldehydes are formed. The catalyst can be separated by extraction of the organic products with hexane and recycled for at least four times with only a modest loss of activity and no effect on selectivity. [source] Bismuth Triflate-Catalyzed Addition of Allylsilanes to N -Alkoxycarbonylamino Sulfones: Convenient Access to 3-Cbz-Protected CyclohexenylaminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Thierry Ollevier Abstract Bismuth triflate was found to be an efficient catalyst in the Sakurai reaction of allyltrimethylsilanes with N -alkoxycarbonylamino sulfones. The reaction proceeded smoothly with a low catalyst loading of Bi(OTf)3,4,H2O (2,5,mol%) to afford the corresponding protected homoallylic amines in very good yields (up to 96%). A sequential allylation reaction followed by ring-closing metathesis delivers 6,8 membered 3-Cbz-protected cycloalkenylamines. [source] Copper(II) Triflate as a Source of Triflic Acid: Effective, Green Catalysis of Hydroalkoxylation ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Mathieu J.-L. Abstract The hydroalkoxylation of dicyclopentadiene (DCPD) and norbornene (NB) with 2-hydroxyethyl methacrylate (HEMA) for the synthesis of industrially relevant monomers has been investigated with various metal-based Lewis acids and strong Brønsted acids. In the absence of other additives, copper(II) triflate is the most efficient catalyst system. Kinetics, electron spin resonance (ESR), catalyst poisoning and cross experiments indicate that triflic acid (TfOH) is the true active catalyst in these reactions. This in situ generation of TfOH occurs via reduction of Cu(OTf)2 by the olefin reagent (DCPD, NB). The copper ions present in the reaction mixture act as radical polymerization retardants, preventing polymerization of HEMA (which is observed with most other metal salts and strong Brønsted acids investigated), thus improving the selectivity and yield (up to 95%) for the desired products. These observations have led to the development of a highly effective green process, using bulk reagents (no solvent) and a cheap, metal-free catalyst system, based on TfOH and a phenolic radical inhibitor (2,5-di- tert -butylhydroxytoluene, BHT). [source] Sequential Copper-Catalyzed Rearrangement,Allylic Substitution of Bicyclic Hydrazines with Grignard ReagentsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Stefano Crotti Abstract The problem of the synthesis of trans- 1,4-disubstituted hydrazino- and aminocyclopentenes has been resolved by a sequential copper-catalyzed rearrangement,allylic alkylation of 2,3-diazabicyclo[2.2.1]heptenes. The cis -fused 5,5-membered allylic carbazate which is formed in situ by a novel copper(II) triflate [Cu(OTf)2]/(±)-BINAP-catalyzed rearrangement, can be alkylated with a broad spectrum of Grignard reagents with a predominant SN2,-regioselectivity. The N-Boc protecting group proved to be optimal as regards yields, reaction times and regioselectivities. [source] Catalytic Deoxygenation of 1,2-Propanediol to Give n -PropanolADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Marcel Schlaf Abstract Deoxygenation of 1,2-propanediol (1.0,M in sulfolane) catalyzed by bis(dicarbonyl)(,-hydrido)(pentamethylcyclopentadiene)ruthenium trifluoromethanesulfonate ({[Cp*Ru(CO)2]2(,-H)}+OTf,) (0.5 mol%) at 110,°C under hydrogen (750 psi) in the presence of trifluoromethanesulfonic acid (HOTf) (60,mM) gives n -propanol as the major product, indicating high selectivity for deoxygenation of the internal hydroxy group over the terminal hydroxy group of the diol. The deoxygenation of 1,2-propanediol is strongly influenced by the concentration of acid, giving faster rates and proceeding to higher conversions as the concentration of HOTf is increased. Propionaldehyde was observed as an intermediate, being formed through acid-catalyzed dehydration of 1,2-propanediol. This aldehyde is hydrogenated to n -propanol through an ionic pathway involving protonation of the aldehyde, followed by hydride transfer from the neutral hydride, dicarbonyl(pentamethylcyclopentadiene)ruthenium hydride [Cp*Ru(CO)2H]. The proposed mechanism for the deoxygenation/hydrogenation reaction involves formation of a highly acidic dihydrogen complex [Cp*Ru(CO)2(,2 -H2)]+ OTf,. [source] Ligand-Accelerated Asymmetric [1,2]-Stevens Rearrangment of Sulfur Ylides via Decomposition of Diazomalonates Catalyzed by Chiral Bisoxazoline/Copper ComplexADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009Jian-Ping Qu Abstract The first example of catalytic asymmetric [1,2]-Stevens rearrangement reaction of 1,3-oxathiolanes with diazomalonates has been developed and up to 90% ee is achieved by the bisoxazoline 4e/copper(II) triflate [Cu(OTf)2] complex. [source] Highly Enantioselective Catalytic Alkynylation of Ketones , A Convenient Approach to Optically Active Propargylic AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14 2006Gui Lu Abstract The development of highly enantioselective catalysts involving Cu(OTf)2 and chiral camphorsulfonamides for the alkynylation of ketone is described. The influences of Lewis acids, reaction conditions and chiral ligands on the outcome of the reaction are discussed. The best enantioselectivity (up to 97,% ee) was obtained in the alkynylation of 2,-chloroacetophenone. The scope of the reaction is also examined. [source] Water-Soluble Group 8 and 9 Transition Metal Complexes Containing a Trihydrazinophosphaadamantane Ligand: Catalytic Applications in Isomerization of Allylic Alcohols and Cycloisomerization of (Z)-Enynols in Aqueous MediumADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Abstract An optimized synthesis of the 2,4,10-trimethyl-1,2,4,5,7,10-hexaaza-3-phosphatricyclo[3.3.1.13,7]decane ligand (THPA) is described. It readily reacts with the dimers [{RuCl(,-Cl)(,6 -arene)}2] and [{MCl(,-Cl)(cod)}2] to yield the corresponding mononuclear complexes [RuCl2(THPA)(,6 -arene)] [arene=C6H6 (4a), p -cymene (4b), 1,3,5-C6H3Me3 (4c), C6Me6 (4d)] and [MCl(THPA)(cod)] [M=Rh (7a), Ir (7b)], respectively. Treatment of 4a and b with MeOTf affords the cationic derivatives [RuCl2(THPA-Me)(,6 -arene)][OTf] {arene=C6H6 (5a), p -cymene (5b); THPA-Me=1,2,4,10-tetramethyl-2,4,5,7,10-pentaaza-1-azonia-3-phosphatricyclo[3.3.1.13,7]decane}. The arene-ruthenium(II) complexes 4a,d and 5a and b are efficient catalysts for the redox isomerization of allylic alcohols into carbonyl compounds in both THF and aqueous media. The catalytic systems can be recycled by a simple extraction process and used in up to 4 consecutive runs. All the water-soluble complexes prepared in this work are able to promote the cycloisomerization of (Z)-enynols to afford furans in water, the best performance being obtained with the iridium catalyst 7b. Furthermore, 7b has shown an excellent recyclability (10 runs). This study represents the first example of iridium-catalyzed cycloisomerization of (Z)-enynols. [source] | ||||||||||||||||||||||||||||