Metals In Liquid Ammonia Research Articles

Palladium-catalyzed phenyl-selenylation with n-Bu 3SnSePh in one-pot two-step reactions

We have studied the Pd-catalyzed cross-coupling reaction of a stannane derived from selenium n-Bu 3SnSePh ( 1) with aryl and perfluoroalkyl iodides. Herein a very efficient one-pot two-step selenylation reaction to form a C–Se bond is reported. Ph 2Se 2 reacts with Na metal in liquid ammonia yielding PhSe − ions. To this solution n-Bu 3SnCl was added to afford 1, which was introduced in the palladium-catalyzed coupling reaction without isolation. These reactions afford functionalized diarylselenides and phenylperfluroalkyl selenides from good to high yields (38–98%).

Homoleptic Rare Earth Dipyridylamides [Ln2(N(NC5H4)2)6], Ln = Ce, Nd, Sm, Ho, Er, Tm, Yb, and Sc: Metal Oxidation by the Amine Melt and in 1,2,3,4-Tetrahydroquinoline with the Focus of Different Metal Activation by Amalgams, Liquid Ammonia, and Microwaves

Homoleptic dimeric dipyridylamide complexes of the rare earth elements are obtained by solvent-free oxidation reactions of the metals with melts of 2,2'-dipyridylamine. As the thermal stabilities of the ligand as well as the amide complexes are limiting factors in these high-temperature syntheses, several different metal activation procedures have been investigated: the formation of Ln amalgams and dissolution of the metals in liquid ammonia as well as coupling to microwaves. For comparison with a solvent that shows low solubility of the metals and products, reactions in 1,2,3,4-tetrahydroquinoline were also carried out. For all lanthanides and group 3 metals used homoleptic dimers of the formula [Ln(2)(Dpa)(6)], Ln = Ce (1), Nd (2), Sm (3), Ho (4), Er (5), Tm (6), Yb (7), and Sc (8) and Dpa- = (C5H4N)2N-, were obtained, all containing trivalent rare earth ions with a distorted square antiprismatic nitrogen coordination. Due to the large differences in the ionic radii of the metal ions, two different structure types are found that crystallize in the space groups P2(1)/c and P2(1)/n with the border of the two types being between Tm and Yb. The orientations of two 1,3/1,3-double chelating and linking dipyridylamide ligands (Dpa(-) = (C(5)H(4)N)(2)N(-)) result in different overall orientations of the dimers and thus two structure types. All compounds were identified by single-crystal X-ray analysis. Mid-IR, far IR, and Raman spectroscopy, microanalyses, and simultaneous DTA/TG as well as mass spectrometry regarding their thermal behavior were also carried out to characterize the products. Crystal data for the two types follow. Ce (1): P2(1)/n; T = 170(2) K; a = 1063.0(1), b = 1536.0(1), c = 1652.0(2) pm; beta = 101.60(1) degrees ; V = 2642.2(3) x 10(6) pm(3); R(1) for F(o) > 4sigma(F(o)) = 0.046, wR(2) = 0.120. Sc (8): P2(1)/c; T = 170(2) K; a = 1073.0(1), b = 1506.2(2), c = 1619.8(2) pm; beta = 103.16(9) degrees ; V = 2548.9(5) x 10(6) pm(3); R(1) for F(o) > 4sigma(F(o)) = 0.038, wR(2) = 0.091.

Reduction of p-terphenyl, p-quaterphenyl and p-sexiphenyl using alkali metal in liquid ammonia: Process and characterization of the reduced compounds

Oligomers of PPP ( p-terphenyl, p-quaterphenyl and p-sexiphenyl) were doped using Na or K to promote a reduction. The used method, with liquid ammonia resulted in a solid state doped material without insertion of solvent. The characterization with XPS and Raman spectroscopy showed the formation of at least one phase of the doped oligomer, which contains dianions (bipolarons).

Synthesis and characterization of CuO nanoparticles from liquid ammonia

A new type of CuO nanoparticles were synthesized in liquid ammonia in the presence of sodium metal. First, Cu nanoparticles were obtained by reducing copper nitrate with the alkali metal in liquid ammonia, then, CuO nanoparticles were formed in the ambient conditions. The morphology and structure of as-prepared CuO nanoparticles were characterized by TEM and XRD, and the reason of aggregation of CuO nanoparticles was supposed.

Synthesis and characterization of samarium, europium and ytterbium aryloxidesCrystal structure of [Yb6(OH)4(OC6H4OMe)14]a4THF

Abstract The reactions of samarium, europium and ytterbium metals with the potential bidentate ligand 2-methoxyphenol were investigated. The europium and ytterbium aryloxides were synthesized by dissolution of the metals in liquid ammonia, whereas the samarium aryloxide was synthesized by metal vapour synthesis (MVS). The compounds obtained were formulated as Ln(OC 6 H 4 OMe) 3 , Ln=Sm, Yb and Eu(OC 6 H 4 OMe) 2 . Recrystallization of Yb(OC 6 H 4 OMe) 3 in the presence of THF/pentane resulted in the crystallographically characterized complex [Yb 6 (μ 3 -OH) 4 (μ-OC 6 H 4 -η-OMe) 10 (OC 6 H 4 -η-OMe) 2 (OC 6 H 4 OMe) 2 ]·4THF.

Synthesis and characterization of samarium, europium and ytterbium aryloxides: Crystal structure of [Yb 6(OH) 4(OC 6H 4OMe) 14]·4THF

The reactions of samarium, europium and ytterbium metals with the potential bidentate ligand 2-methoxyphenol were investigated. The europium and ytterbium aryloxides were synthesized by dissolution of the metals in liquid ammonia, whereas the samarium aryloxide was synthesized by metal vapour synthesis (MVS). The compounds obtained were formulated as Ln(OC 6H 4OMe) 3, Ln=Sm, Yb and Eu(OC 6H 4OMe) 2. Recrystallization of Yb(OC 6H 4OMe) 3 in the presence of THF/pentane resulted in the crystallographically characterized complex [Yb 6(μ 3-OH) 4(μ-OC 6H 4-η-OMe) 10(OC 6H 4-η-OMe) 2(OC 6H 4OMe) 2]·4THF.

One‐Pot Palladium‐Catalyzed Cross‐Coupling Reaction of Aryl Iodides with Stannylarsanes and Stannylstibanes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

One-pot palladium-catalyzed cross-coupling reaction of aryl iodides with stannylarsanes and stannylstibanes.

[reaction: see text] The reaction of Ph(3)As and Ph(3)Sb with Na metal in liquid ammonia gives Ph(2)M(-) ions (M = As, Sb) that react with n-Bu(3)SnCl to afford n-Bu(3)Sn-MPh(2) (1). The ammonia was allowed to evaporate, and toluene was added. The Pd-catalyzed cross-coupling reactions of these stannanes with aryl iodides afford functionalized triaryl-arsanes and triaryl-stibanes in high yields in a one-pot procedure (80-99%). The use of the commercially available, air-stable, and inexpensive Ph(3)M as the initial reagent and the one-pot process make this method a useful approach. This is the first report on the synthesis of 1 and the exploration of its chemistry.

Electron transfer induced dissociations of 2- and 4-alkyl cyclohexadienones

Several 2- and 4-alkylcyclohexadienones were prepared and shown to accept electrons to produce ketyl radical anions that dissociated rapidly at room temperature to release carbon-centered radicals and an aromatic phenoxide type anion. In the PET process with benzyl-substituted cyclohexadienones, initiated with triethylamine, the benzyl radicals dimerised or abstracted an H-atom from solvent. In electrochemical reductions, and in reductions with alkali metals in liquid ammonia, the benzyl radicals were further reduced to anions.

One‐Pot Palladium‐Catalyzed Phosphination of Aryl Iodides with Ph2PSnR3.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Alloying of Yb–Cu and Yb–Ag utilizing liquid ammonia metal solutions of ytterbium

In the course of the studies on preparation of novel compounds using the dissolution of Eu or Yb metals in liquid ammonia, the formation of Yb–Cu and Yb–Ag intermetallic films has been found. When Cu or Ag metal powders were placed in a reactor containing a solution of Yb metal in liquid ammonia, the dissolved Yb readily react with the Cu or Ag metal particles to form surface alloy compounds. X-ray diffraction of Yb–Cu showed that upon thermal treatment above 673K, the Yb metal deposited on the Cu particles reacted together to be transformed into the YbCu6.5 intermetallic compound. A characteristic endothermic peak at 749K, due to alloying of Yb–Cu, was observed by the differential scanning calorimeter measurements. By use of the high reactivity of liquid ammonia metal solutions of ytterbium, it was found that the ytterbium intermetallic films were readily formed under mild conditions. Yb–Cu and Yb–Ag exhibited enhanced catalytic activity for the hydrogenation of ethene as a result of alloying.

One-pot palladium-catalyzed phosphination of aryl iodides with Ph 2PSnR 3

We found a very efficient one-pot phosphination reaction starting with Ph 3P, which by reaction with Na metal in liquid ammonia gives Ph 2P − ions that reacted with R 3SnCl to afford (trialkylstannyl)diphenylphosphine. The palladium-catalyzed coupling reaction of these stannanes with aryl iodides yield functionalized phosphines in high yield (69–97%). The use of Ph 3P as starting reagent, the endurance of the reaction to a wide variety of functional groups and the easiness of a one-pot reaction make this method a useful and versatile approach to tertiary phosphine oxides.

Cover Picture: Chem. Eur. J. 12/2002

The cover picture shows the domains of the electron localization function (ELF) being enveloped by the corresponding 0.8 isosurface in [C70(CH3)2]2−, which was taken as a model compound in the theoretical investigations of the linear polymeric fulleride chains [C]. Such chains were synthesised by reducing C70 with alkaline earth or rare earth metals in liquid ammonia. For the strontium compound [Sr(NH3)8]C70⋅3 NH3 it was possible to determine precisely the individual positions of the carbon atoms in the fulleride by single-crystal X-ray structure analysis. The structural features of the monomeric units in the chain agree very well with the results of quantum-chemical calculations for the model compound. By analysing the ELF, the nature of the various CC bonds in the cage can be determined. The consequences for the reaction behaviour of reduced C70 are discussed in more detail by M. Jansen et al. on p. 2769 ff.

Synthesis, Characterization, and Chemistry of Dimethyl Sulfide Derivatives of closo-B10H102-

The reaction of Cs2[B10H10] with DMSO in acid produces the disubstituted 1,10-, 1,6-, and 2,7(8)-isomers of (Me2S)2B10H8 as well as the monosubstituted [(Me2S)B10H9]- anion. Through a modified procedure, the trisubstituted compound 1,10-(Me2S)2-2-(MeS)B10H7 was prepared and characterized. The 1,10-(Me2S)2B10H8 isomer was converted to the enantiomers 2,7-(Me2S)2B10H8 and 2,8-(Me2S)2B10H8 which were separated on a chiral column. The 1,6-(Me2S)2B10H8 isomer was converted to a mixture of 1,10-(Me2S)2B10H8 and 2,3-(Me2S)2B10H8. These polyhedral rearrangements are believed to occur through the diamond-square-diamond mechanism. The 1,6- and 1,10-(Me2S)2B10H8 isomers were reduced with alkali metal in liquid ammonia to produce the dianions [1,6-(MeS)2B10H8]2- and [1,10-(MeS)2B10H8]2-, respectively. Sodium ethanethiolate was used for the reduction of [1-(Me2S)B10H9]- and 1,10-(Me2S)2B10H8 to form [1-(MeS)B10H9]2- and [1-(MeS)-10-(Me2S)B10H8]-, respectively. The structures of 1,10-(Me2S)2B10H8, 1,6-(Me2S)2B10H8, 2,8-(Me2S)2B10H8, 2,3-(Me2S)2B10H8, 1,10-(Me2S)2-2-(MeS)B10H7, [1-(MeS)-10-(Me2S)B10H8]-, and [1,6-(MeS)2B10H8]2- were determined by single-crystal X-ray diffraction analysis.

Spindle-Type EuO Nanocrystals and Their Magnetic Properties

Abstract EuO nanocrystals were prepared by liquid phase reaction of europium metal in liquid ammonia for the first time. TEM revealed that the EuO nanocrystals had a spindle shape with mean length of 280 nm (a) by mean width of 95 nm (b). The SQUID measurement showed that the EuO nanocrystals turned into ferromagnetic phase at 70 K and 150 K.

Synthesis of symmetrical triarylphosphines from aryl fluorides and red phosphorus: scope and limitations

The reaction of aryl fluorides with phosphide anion, generated in situ from the reduction of red phosphorus by lithium metal in liquid ammonia, gave symmetrical triarylphosphines in fair to good yields. Phosphonodiamide, sulfonamide, 2-oxazolyl, and nitrile groups were stable to the reaction conditions, while nitro and bromo substituents were not. para-Substituted aryl fluorides gave higher yields than meta-substituted aryl fluorides, and ortho-substituted aryl fluorides failed to react.

Critical points of metallic plasmas and electrolytes

liquid-gas critical point of alkalis and the consolute critical point of alkali metal in liquid ammonia have been theoretically estimated The proximity to the insulator-metal transition suggests a virtual atomic structure of strongly coupled metallic plasmas. In contrast to the OCP model, the estimates for such a structure reasonably agree with available experimental data. Similarly, the critical parameters of charged hard spheres, estimated for a quasimolecular structure, agree with recent Monte-Carlo simulations.

Lanthanide (Eu or Yb)-promoted Ni, Cu and Ag-catalyzed transfer hydrogenation with NH 3 as a hydrogen donor

Novel lanthanide (Ln)-promoted Ni, Cu and Ag catalysts prepared by the reaction of Ni/SiO 2, Cu/SiO 2 and Ag/ZrO 2 with the dissolved Eu or Yb metals in liquid ammonia have been studied for the catalytic transfer hydrogenation of ethene, buta-1,3-diene and propyne. The transfer hydrogenation with the aid of ammonia as a hydrogen donor was greatly enhanced by the Ln-promoted catalysts. The catalytic activity for the transfer hydrogenation increased with increasing lanthanide content in the bimetallic catalysts, which evidently reflected synergetic effects between the lanthanide and transition metals. The transfer hydrogenation of ethene with ammonia over Eu–Ni/SiO 2 proceeded to form ethane and nitrogen, maintaining the following stoichiometric relationships: 3C 2H 4+2NH 3→3C 2H 6+N 2 The catalytic hydrogen transfer from ammonia to buta-1,3-diene or propyne similarly followed the stoichiometric relationships. The Ln-promoted catalysts showed substrate selectivity for the transfer hydrogenation using ammonia as the hydrogen source; Ln–Ni/SiO 2 was reactive for ethene and buta-1,3-diene, but not for propyne. Ln–Cu/SiO 2 was active for propyne and buta-1,3-diene. Ln–Ag/SiO 2 was relatively active for buta-1,3-diene. The major factors governing the catalytic transfer hydrogenation seem to be involved in the participation of the acceptor and donor molecules in the hydrogen transfer step rather than the ease of dehydrogenation of ammonia and the processes of hydrogen addition to the acceptor. The catalytic hydrogen transfer from ammonia to acceptor molecules occurs concertedly.

Infrared spectra of dinitrogen adsorbed on bimetallic lanthanide (Eu or Yb)-Ni/SiO2 catalysts

Bimetallic lanthanide (Ln: Eu or Yb)–Ni/SiO2 catalysts prepared by the use of dissolution of lanthanide metals in liquid ammonia have been studied by infrared spectroscopy for dinitrogen adsorption. The infrared spectra were measured at 133–300 K using Ln–Ni/SiO2 obtained when the Eu or Yb metal dissolved in liquid ammonia reacted with 20 mass% Ni/SiO2 in different ratios. Infrared spectra for Eu–Ni/SiO2 showed absorption bands at 2336, 2265, 2254 and 2227 cm−1 at 133 K, which disappeared upon evacuation. The adsorbed state was found to be all molecular from the isotope shift using 28N2 and z30N28. The bands at 2254 and 2227 cm−1 of them were assigned to new adsorbed dinitrogen species resulting from synergetic interactions between the europium and nickel metal. The concentration of adsorbed dinitrogen on Eu–Ni/2 varied markedly with the Eu/Ni ratios, and particularly, it increased in the region of high Eu content. Upon introduction of ytterbium onto nickel, new bands at 2254 and 2226 cm−- similarly appeared. However, the dependence of dinitrogen adsorption as a function of Yb content in Yb–Ni/SiO2> was somewhat different from that for Eu–Ni/SiO2. The effects of lanthanide on the surface of Ln–Ni/SiO2 were discussed in connection with the variation in catalytic properties.

Preparation of O-(Aminopropyl)inulin

Inulin ethers carrying primary amino groups have many potential applications. O-(Aminopropyl)inulin is obtained from O-(cyanoethyl)inulin by reduction of the nitrile groups. Heterogeneously catalyzed hydrogenation using Raney-cobalt as the catalyst resulted in only partial conversion of the O-cyanoethyl into O-aminopropyl groups. Complete conversion of the nitriles to primary amines was achieved by a homogeneous reduction with an excess of sodium borohydride and cobaltous chloride or with metals in liquid ammonia–methanol. Optimal results were obtained with the latter method; 83% of the substituents were converted into primary amines and 17% were lost by dealkylation.