Reaction Of Lithium Amides Research Articles

Evaluation of Pd→B Interactions in Diphosphinoborane Complexes and Impact on Inner-Sphere Reductive Elimination.

The dative Pd→B interaction in a series of RDPBR’ Pd0 and PdII complexes (RDPBR’=(o‐PR2C6H4)2BR’, diphosphinoborane) was analyzed using XRD, 11B NMR spectroscopy and NBO/NLMO calculations. The borane acceptor discriminates between the oxidation state PdII and Pd0, stabilizing the latter. Reaction of lithium amides with [(RDPBR’)PdII(4‐NO2C6H4)I] chemoselectively yields the C−N coupling product. DFT modelling indicates no significant impact of PdII→B coordination on the inner‐sphere reductive elimination rate.

Hydrogen absorption and lithium ion conductivity in Li6NBr3

The reaction of lithium amide and imide with lithium halides to form new amide halide or imide halide phases has led to improved hydrogen desorption and absorption properties and, for the amides, lithium ion conductivities. Here we investigate the effect of bromide incorporation on the ionic conductivity and hydrogen absorption properties of lithium nitride. For the first time we show that it is possible for a lithium halide nitride, the cubic bromide nitride Li6NBr3, to take up hydrogen—a necessary condition for potential use as a reversible solid-state hydrogen storage material. Powder X-ray diffraction showed the formation of Li2Br(NH2) and LiBr, and Raman spectroscopy confirmed that only amide anions were present and that the hydrogen uptake reaction had gone to completion. The lithium ion conductivity of Li6NBr3 at the hydrogenation temperature was found to be less than that of Li3N, which may be a significant factor in the kinetics of the hydrogenation process.

Hydrogen storage and ionic mobility in amide–halide systems

We report the results of a systematic study of the effect of halides on hydrogen release and uptake in lithium amide and lithium imide, respectively. The reaction of lithium amide and lithium imide with lithium or magnesium chloride, bromide and iodide resulted in a series of amide-halide and imide-halide phases, only two of which have been reported previously. On heating with LiH or MgH2, the amide-halides synthesised all released hydrogen more rapidly than lithium amide itself, accompanied by much reduced, or in some cases undetectable, release of ammonia by-product. The imide-halides produced were found to hydrogenate more rapidly than lithium imide, reforming related amide-halide phases. The work was initiated to test the hypothesis that the incorporation of halide anions might improve the lithium ion conductivity of lithium amide and help maintain high lithium ion mobility at all stages of the de/rehydrogenation process, enhancing the bulk hydrogen storage properties of the system. Preliminary ionic conductivity measurements indicated that the most conducting amide- and imide-halide phases were also the quickest to release hydrogen on heating and to hydrogenate. We conclude that ionic conductivity may be an important parameter in optimising the materials properties of this and other hydrogen storage systems.

An ultrasonic wave-assisted synthesis of meso-amidinophenyl substituted porphyrins

With the aid of an ultrasonic irradiation, meso-amidinophenyl substituted porphyrins were prepared by the reaction of lithium amide and meso-cyanophenyl porphyrins. This approach can give the derivatized porphyrins in very high yields and very short reaction times as compared to the conventional thermal method.

Synthesis of (2-aminoethyl)ferrocenes from the reaction of lithium amides with vinylferrocene

Lithium amides react with vinylferrocene in the presence of TMEDA to provide the corresponding (2-aminoethyl)ferrocenes in good to excellent yields. A range of secondary amines can be employed in this amidolithiation reaction, with cyclic derivatives affording particularly good yields of the 2-aminoethyl-substituted ferrocene product. This operationally simple procedure provides one of the most straightforward routes to this class of mono-substituted ferrocene.

One-Pot Synthesis of 1,1‘-Bis(2-amino)ethyl-Substituted Ferrocenes from the Reaction of Spiro[2.4]hepta-4,6-diene with Lithium Amides: An Expedient Route into Functionalized Ferrocenophanes

The reaction of lithium amides with spiro[2.4]hepta-4,6-diene 2 affords the corresponding (2-aminoethyl)CpLi cyclopropane-ring-opened product that can be trapped in situ with FeCl2 to provide a direct route into 1,1‘-bis-aminoethyl ferrocenes 3. In addition to the desired bis-amine products, a number of interesting ferrocene byproducts have been identified. Their formation can be attributed to the associated Bronsted basicity of the lithium amide nucleophiles and their ability to participate in SET processes, opening-up alternative reaction pathways. The desired aminoethyl-substituted ferrocene products are derived primarily from direct nucleophilic cyclopropane ring-opening rather than via amidolithiation of vinylCp intermediates.

Formation of transition-metal nitrides from the reactions of lithium amides and anhydrous transition-metal chlorides

Reaction of anhydrous metal chlorides and lithium amide at 160–400 °C induces an exothermic reaction with formation of lithium chloride and an amorphous material. Trituration of the product with tetrahydrofuran (THF) followed by thermolysis at 700 °C for 1–2 h results in the formation of crystalline metal nitrides of varying composition (TiN, ZrN, HfN, VN, NbN, TaN, Cr2N, CrN, Mo2N, W2N, Mn3N2 and Zn3N2). Reactions involving iron, nickel, copper and indium chlorides with lithium amide yielded the metallic elements. The reactions of lithium dimethylamide and lithium diisopropyl amide and selected metal chlorides also produced metal nitrides under comparable reaction conditions. The metal nitrides were analysed by powder XRD, microanalysis, magnetic moment measurements, FTIR and SEM/EDXA.

Reaction of lithium amide with methane: an ab initio and atoms in molecules study

The reaction of lithium amide with methane was studied with ab initio calculations, and the electron density function was analyzed using the theory of atoms in molecules. The transition state for the reaction is a highly ionic species that can be modeled approximately as an ionic aggregate. The nature and evolution of the bonds were monitored throughout the reaction and related to the accompanying changes in the behavior of the charge density at the bond critical points and in the properties of the individual atoms. The contributions of each atom to the energies of reaction and activation were determined. The HF/6-31G * level of theory was tested by an MCSCF calculation of the transition state and shown to perform adequately in the description of the reaction

Syntheses and Structures of [NMe2(μ-NMe2)GaCl]2and [TMP(μ-OEt)GaCl]2(TMP = 2,6-Tetramethylpiperidide)

Abstract The bis-dimethylamido gallium chloride, [NMe2(μ-NMe2)GaCl]2 (I) may be prepared by the reaction of two equivalents of lithium amide with GaCl3. The amido ethoxide gallium chloride, [TMP(μ-OEt)GaCl]2 (2), (TMP = tetramethylpiperidide) is formed in the reaction of lithium amide with GaCl3 in diethylether. The structures of 1 and 2 have been determined by X-ray methods. Crystals of 1 are orthorhombic, space group P212121, with a = 8.428(4), b=15.10(1), c=13.138(6) A, Z = 4. Crystals of 2 are monoclinic, space group P21/n, with a = 8.542(1), b = 12.457(1), c = 12.959(1)A, β = 95.483(9), Z = 2. The R values for 1 and 2 are 0.066 and 0.054, respectively. The solid state structure of 1 consists of a nitrogen-bridged dimer, while 2 consists of an oxygen-bridged dimer.

EPR evidence for a single electron transfer mechanism in reactions of aromatic ketones with lithium amides

Direct spectroscopic evidence (EPR) supporting a single electron transfer mechanism in the reaction of lithium amides with aromatic ketones is presented.