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Aluminum hydride (AlH3) has attracted wide attention due to its high gravimetric and volumetric hydrogen capacity. AlH3 can easily release hydrogen when heated at relatively low temperature. Such high hydrogen density and low dehydrogenation temperature make it one of the most promising high-energy fuels for solid propellants. In particular, AlH3 as a component of solid propellants may greatly increase the specific impulse of rocket engines. However, AlH3 exhibits low chemical and thermal stability in an ambient atmosphere. In this paper, the research progress about the synthesis, dehydrogenation thermodynamics, and kinetics, the stabilization of AlH3 over the past decades are reviewed, with the aim of exploring more a economical synthesis and suitable stabilization methods for large-scale use in solid propellants. Finally, some suggestions regarding future research directions in this filed are proposed. [ABSTRACT FROM AUTHOR]

CO2 reduction is appealing for the long‐term production of high‐value fuels and chemicals. Herein, using density functional theory (DFT) based calculations, we study the CO2 reduction pathway to formic acid using aluminum hydride and phosphine derivatives. Our primary focus is on aluminum hydride derivatives, aimed at improving the efficiency of the CO2 reduction process. Substituents with σ‐donating properties at the aluminum center are discovered to lower the activation barriers. We demonstrate how di‐tert‐butylphosphine oxide (LB‐O)/di‐tert‐butylphosphine sulfide (LB‐S)/di‐tert‐butylphosphanimine (LB‐N) work together with aluminum hydride to facilitate CO2 reduction process and generate in‐situ frustrated Lewis pairs (FLPs), such as FLP‐O, FLP‐S, and FLP‐N. The activation strain model (ASM) analysis reveals the significance of strain energy in determining activation barriers. EDA‐NOCV and PIO analyses elucidate the orbital interactions at the corresponding transition states. Furthermore, the study delves into the activation of various small molecules, such as dihydrogen, acetylene, ethylene, carbon dioxide, nitrous oxide, and acetonitrile, using those in‐situ generated FLPs. The study highlights the low activation barriers and emphasizes the potential for small molecule activation in this context. [ABSTRACT FROM AUTHOR]

The reaction of the amine‐stabilized alane (NMe3) ⋅ AlH31 with the backbone‐saturated N‐heterocyclic carbene (NHC) SIDipp (SIDipp=1,3‐bis‐{2,6‐di‐iso‐propyl‐phenyl}‐imidazolidin‐2‐ylidene) at 0 °C yielded the NHC alane adduct (SIDipp) ⋅ AlH32. Reaction at elevated temperatures or prolonged reaction at room temperature gave the product of a ring expansion reaction (RER) of the NHC, (NMe3) ⋅ AlH(RER‐SIDippH2) 3 ⋅ (NMe3). Subsequent reaction of the latter with sterically less hindered NHCs (IMeMe {=1,3,4,5‐tetramethyl‐imidazolin‐2‐ylidene}, IiPrMe {=1,3‐di‐iso‐propyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene}, and IiPr {=1,3‐di‐iso‐propyl‐imidazolin‐2‐ylidene}) afforded the NHC‐stabilized RER‐products (NHC) ⋅ AlH(RER‐SIDippH2) 3 ⋅ (NHC) (NHC=IMeMe, IiPrMe, IiPr), while no reaction was observed with the sterically more demanding NHCs IDipp (=1,3‐bis‐{2,6‐di‐iso‐propyl‐phenyl}‐imidazolin‐2‐ylidene), SIDipp and ItBu (=1,3‐di‐tert‐butyl‐imidazolin‐2‐ylidene). The compounds 3 ⋅ (NHC) were also obtained starting from (SIDipp) ⋅ AlH32 and NHC at room temperature. Heating solutions of (SIDipp) ⋅ AlH32 without additional base to 95 °C resulted in decarbonization of the NHC and substitution of the carbene carbon atom with aluminum hydride under loss of ethene. Subsequent dimerization afforded cis‐[AlH{μ‐N(Dipp)CH2CH2N(Dipp)}]24_dimer. Heating solutions of the NHC‐ligated aluminum alkyls (SIDipp) ⋅ AlR32R (R=Me, Et) to 145 °C instead led to complete scission of the NHC backbone with evolution of ethene and isolation of the dialkylaluminium(III) amidinates {DippNC(R)NDipp}AlR25R (R=Me, Et). [ABSTRACT FROM AUTHOR]

Thin films of Al as interconnect materials and those of AlN as wide bandgap semiconductor and piezoelectric material are of great interest for microelectronic applications. For the fabrication of these thin films via chemical vapor deposition (CVD) based routes, the available precursor library is rather limited, mostly comprising aluminium alkyls, chlorides, and few small amine-stabilized aluminium hydrides. Herein, we focused on rational precursor development for Al, their characterization and comparison to existing precursors comprising stabilized aluminium hydrides. We present and compare a series of potentially new and reported aluminium hydride precursors divided into three main groups with respect to their stabilization motive, and their systematic structural variation to evaluate the physicochemical properties. All compounds were comprehensively characterized by means of nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), elemental analysis (EA), electron-impact ionization mass spectrometry (EI-MS) and thermogravimetric analysis (TGA). Promising representatives were further evaluated as potential single source precursors for aluminium metal formation in proof-of-concept experiments. Structure and reaction enthalpies with NH3 or H2 as co-reactants were calculated via first principles density functional theory simulations and show the great potential as atomic layer deposition (ALD) precursors for Al and AlN thin films. [ABSTRACT FROM AUTHOR]

The reduction of interfacial interaction and the deterioration of processing properties of aluminum hydrides (AlH3) is the main challenges preventing its practical application. Here, a simple and effective core–shell structure aluminum hydrides@polydopamine (AlH3@PDA) complex was constructed through in-situ polymerization. The evolution of element states on the surface of AlH3 conducted by X-ray photoelectron spectroscopy indicated the successful introduction of PDA to form the core@shell structure, the thickness of the PDA coated layer increased with the increasing PDA dosage from 0.1 to 1.6% in mass fraction, and the maximum of thickness is 50 nm in TEM testing. Py GC/MS results proved that the increase of dopamine concentration leads to higher proportions of self-assemble units, whereas lower dopamine concentrations favor higher levels of chemical bonded components. Regarding whether PDA is a covalent polymer or a noncovalent aggregate of some species, the formation of intermediates, such as dopaminechrome and 5,6-dihydroxyindole played an important role to coordination interaction with AlH3 in FTIR, Raman, and UV–Vis spectra testing. Compared with pure AlH3, the formation of organic PDA coating improved AlH3 heat resistance. The adhesion work with GAP adhesive was also improved from 107.02 J/m2 of pure AlH3 to 111.13 mJ/m2 of AlH3@PDA-5 complex. This paper provides well support for further practical application of AlH3 in solid propellants. [ABSTRACT FROM AUTHOR]

Although hydrides such as LaH10 are experimentally confirmed to possess high superconducting critical temperature (Tc) of 250-260 K under 170-200 GPa, it is still a tough challenge to be applied. It is highly anticipated to find hydride superconductors with relatively high Tc at low or ambient pressure. Reducing the dimensionality of materials can induce unexpected properties that are distinct from their bulk counterparts, and whether it can modulate the superconducting properties deserves further investigation. Herein, a new 2D monolayer aluminum hydride h-AlH2 is theoretically predicted under ambient pressure based on the first-principles calculations. Since the electronic structures of h-AlH2 reveal the metallicity, the electron-phonon coupling (EPC) and possible phonon-mediated superconductivity are investigated. Based on the isotropic Eliashberg equation, the calculated EPC constant λ of h-AlH2 is 1.16, and the Tc is up to 42.6 K. The EPC mainly originates from the coupling between electrons of Al-s, px, py, and H-s orbitals and the in-plane vibration modes of H atoms. Especially, the Tc can be enhanced to 63.7 K by applying 3% biaxial tensile strain. Thus, the predicted h-AlH2 provides a new platform for finding hydride superconductors in lowdimensional materials at ambient pressure. [ABSTRACT FROM AUTHOR]

A novel, simple, eco-friendly, non-toxic aluminium catalyst was synthesised for the chemoselective reduction of α,β-unsaturated ketones. A wide range of ketones were achieved with excellent yields, mild conditions, and low catalyst loading. Furthermore, this unprecedented method allowed for the stereoselective reduction of natural ketones. [ABSTRACT FROM AUTHOR]

The reaction of aluminum bis-formate acenaphthene-1,2-diimine complex [(ArBIG-bian)Al(μ-OC(H)O)2Li(Thf)2] (I) (ArBIG-bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene), prepared by binding carbon dioxide by aluminum diimine hydride [(ArBIG-bian)Al(H)2]–[Li(Thf)4]+, with borane dimethyl sulfide and ammonia was studied. The reaction of I with BH3∙SMe2 (1 : 1) in toluene affords the product of hydroboration of one formate group [(ArBIG-bian)Al(μ-OC(H)O)(OB(H)OCH3)Li(Thf)]2 (II), while the reaction of I with BH3∙SMe2 (1 : 2) is accompanied by reduction of both formate groups and gives complex [(ArBIG-bian)Al(OBOCH3)2OLi2(Thf)2BH4]2 (III), methoxyboroxine (CH3OBO)3 and, presumably, compound [(ArBIG-bian)AlOCH3]. The reaction of I with one equivalent of ammonia in THF gives adduct [(ArBIG-bian)Al(NH3)(μ-OC(H)O)2Li(Thf)2] (IV), in which ammonia is coordinated to the aluminum atom, while the key bonds in I have not undergone ammonolysis. Compounds II–IV were characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction (CCDC no. 2255017 (II), 2255018 (III), 2255019 (IV)). [ABSTRACT FROM AUTHOR]

The results obtained show that the addition of aluminum (Al) and aluminum hydride (AlH3) to an explosive significantly increases the heat of an explosion (HE) and the TNT equivalent (TE) of an underwater explosion. The compositions with AlH3 are inferior to their Al-containing counterparts in the HE. However, the formulations with AlH3 have the advantage in terms of the number of moles of gaseous products. Replacing Al with AlH3 weakly affects the TE in terms of the energy of a gas bubble, while the TE in terms of the energy of a shock wave is higher for the mixtures with AlH3. The latter is especially noticeable in the case of an explosive with a positive oxygen balance. However, the compositions with AlH3 are inferior to the Al-containing mixtures in terms of volumetric TE. [ABSTRACT FROM AUTHOR]

New ExoMol line lists AloHa for aluminium hydride (AlH and AlD) are presented improving the previous line lists WYLLoT. The revision is motivated by the recent experimental measurements and astrophysical findings involving the highly excited rotational states of AlH in its A 1Π − X 1Σ+ system. A new high-resolution emission spectrum of 10 bands from the A 1Π − X 1Σ+ system of AlD, in the region 17 300–32 000 cm−1 was recorded with a Fourier transform spectrometer, which probes the predissociative A 1Π v  = 2 state. The AlD new line positions are combined with all available experimental data on AlH and AlD to construct a comprehensive set of empirical rovibronic energies of AlH and AlD covering the X 1Σ+ and A 1Π electronic states using the MARVEL approach. We then refine the spectroscopic model WYLLoT to our experimentally derived energies using the nuclear-motion code Duo and use this fit to produce improved line lists for 27AlH, 27AlD, and 26AlH with a better coverage of the rotationally excited states of A 1Π in the predissociative energy region. The lifetimes of the predissociative states are estimated and are included in the line list using the new ExoMol data structure, alongside the temperature-dependent continuum contribution to the photoabsorption spectra of AlH. The new line lists are shown to reproduce the experimental spectra of both AlH and AlD well, and to describe the AlH absorption in the recently reported Proxima Cen spectrum, including the strong predissociative line broadening. The line lists are included into the ExoMol data base www.exomol.com. [ABSTRACT FROM AUTHOR]

Aluminum hydride (AlH3), as a potential new metal fuel, has attracted extensive attention in the field of hydrogen storage materials, propellants and energetic materials due to its excellent properties. In this paper, a new organic liquid phase reduction method was used to prepare AlH3, and the microstructure and composition of the prepared samples were characterized by SEM–EDS, XRD, FT-IR, XPS, etc. The main crystal phase of the prepared AlH3 was α-AlH3, with high quality and no other impurities. The thermal decomposition behavior and non-isothermal reaction kinetics of AlH3 were investigated by TG-DSC. The results show that there are three exothermic stages in the heating process of AlH3: dehydrogenation of AlH3, first oxidation of Al, and second oxidation of Al. The activation energy of the dehydrogenation of AlH3 is 77.8675 kJ/mol (Kissinger method) and 81.4862 kJ/mol (Ozawa method), respectively. The morphology evolution of AlH3 particles during the heating process (300–3000 K) was simulated using a reaction kinetics method based on the ReaxFF force field. The response behavior of AlH3 in the instantaneous high-temperature detonation environment was investigated using the high-energy laser-induced shock wave technique. Under the impact of a high-energy laser (1006 mJ), the AlH3 sample undergoes an ultra-fast reaction and generates a large amount of plasma. The expansion of the plasma pushes the surrounding air to form a supersonic shock wave and propagates forward. The shock wave propagation velocity of AlH3 is 690.99 m/s in the range of 2.1–12.35 μs, and the higher the laser energy, the faster the shock wave propagation velocity. This study provides the basis for the application of AlH3. [ABSTRACT FROM AUTHOR]

We report the isolation and characterization of an unknown reaction product from the reaction of AlBr3 with three equivalents of t‐BuLi. The polymeric and solvent‐free lithium alanate {Li[t‐Bu2AlH2]}n was characterized by X‐ray structure analysis, NMR and IR spectroscopy. The title compound was found to be a suitable starting material for the synthesis of [t‐Bu2AlH]3 by reacting it with readily available [t‐Bu2AlBr]2. [ABSTRACT FROM AUTHOR]

By reacting nitrilium derivative of the closo-dodecaborate anion, Bu4N[B12H11N≡CR] (where R = Me, Et, nPr, iPr, p-tolyl), with lithium aluminum hydride (LiAlH4), N-alkylammonium derivatives of the closo-dodecaborate anion, and Bu4N[B12H11NH2CH2R], were obtained. The reduction reaction procedure was optimized, achieving yields close to quantitative (90–95%). The structure of the compound Bu4N[B12H11NH2CH2CH3] was determined using X-ray structural analysis. It was found that substituting lithium aluminum hydride (LiAlH4) with sodium borohydride (NaBH4) leads to the same products but only upon heating, while the reaction with LiAlH4 proceeds at room temperature. [ABSTRACT FROM AUTHOR]

The quadrupole coupling constant CQ and the asymmetry parameter η have been determined for two complex aluminium hydrides from 27Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The thus obtained data for KAlH4 (CQ=(1.30±0.02) MHz, η=(0.64±0.02)) and NaAlH4 (CQ=(3.11±0.02) MHz, η<0.01) agree very well with data previously determined from MAS NMR spectra. The accuracy with which these parameters can be determined from static spectra turned out to be at least as good as via the MAS approach. The experimentally determined parameters (δiso, CQ and η) are compared with those obtained from DFT‐GIPAW (density functional theory – gauge‐including projected augmented wave) calculations. Except for the quadrupole coupling constant for KAlH4, which is overestimated in the GIPAW calculations by about 30 %, the agreement is excellent. Advantages of the application of the Solomon echo sequence for the measurement of less stable materials or for in situ studies are discussed. [ABSTRACT FROM AUTHOR]

A facile method, refluxing with hydrothermal process, was used to synthesize the fluorinated graphene sheets (FGS) with high F/C ratio. Then, the surface of aluminum hydride (AlH3) was coated with FGS by means of liquid self-assembly process. The structure and performance of FGS were characterized through fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM) and elemental analyzer. FTIR spectra show that the FGS have obvious absorption peak of CF bond. Raman spectra display many defects on FGS. XPS spectra and elemental analysis also prove the existence of CF bond, and the content of fluorine is more than 25%. From SEM photos we can see that FGS have thin layers with some curled wrinkles. TEM photos demonstrate intuitively the FGS has a few layers. At last, the aluminum hydride (AlH3) was coated with FGS by means of liquid self-assembly process, and AlH3 samples before and after treated were characterized through hydrogen content (H%) analysis, X-ray diffraction (XRD), FTIR, SEM and differential thermal analysis (DTA), ect. The results demonstrate that there is only a little FGS on the surface of AlH3, which won't affect the effective H% and release efficiency of hydrogen. AlH3@FGS also reduces the mechanical sensitivity of solid propellant with AlH3, which will remarkably promote the application of AlH3 in the novel high-energy solid propellant.

Ever since our first experimental and computational identification of Al4H6 as a boron analog [X. Li et al., Science 315, 356 (2007)], studies on aluminum hydrides unveiled a richer pattern of structural motifs. These include aluminum-rich hydrides, which follow shell closing electron counting models; stoichiometric clusters (called baby crystals), which structurally correspond to the bulk alane; and more. In this regard, a mass spectral identification of unusually high intense peak of Al4H14−, which has two hydrogen atoms beyond stoichiometry, has remained mostly unresolved [X. Li et al., J. Chem. Phys. 132, 241103 (2010)]. In this Communication, with the help of global minima methods and density functional theory-based calculations, we identify the lowest energy bound structure with a unique Al–H–H–Al bonding. Our electronic structural analysis reveals that two Al2H6 units trap a transient, metastable H2−. In other words, three stable molecules, two Al2H6 and an H2, are held together by a single electron. Our studies provide a pathway to stabilize transient species by making them part of a more extensive system. [ABSTRACT FROM AUTHOR]

The mono‐ and bis‐iodo‐substituted NHC‐stabilized alanes (NHC) ⋅ AlH2I and (NHC) ⋅ AlHI2 offer a convenient entry for further substitution reactions at aluminum. Reactions of (NHC) ⋅ AlH2I 1–4 with one equivalent of NaCp afforded the adducts (NHC) ⋅ AlH2Cp 9–12 (NHC=Me2ImMe (9), iPr2ImMe (10), iPr2Im (11), Dipp2Im (12)). Alane adducts with two Cp substituents (NHC) ⋅ AlHCp213–16 (NHC=Me2ImMe (13), iPr2ImMe (14), iPr2Im (15), Dipp2Im (16)) were prepared by the analogous reaction of (NHC) ⋅ AlHI25–8 using two equivalents of NaCp. The unusual dimeric adducts ((NHC) ⋅ AlH2Cp ⋅ CpMgI)217–19 (NHC=Me2ImMe (17), iPr2ImMe (18), iPr2Im (19)) were obtained from the reaction of 1–3 with MgCp2. [ABSTRACT FROM AUTHOR]

We herein reported the design and synthesis of a ferrocene‐based tetradentate ligand that is featured with modular synthesis and rigid skeleton. Its iron(II) complex facilitates asymmetric direct hydrogenation of ketones without the participation of extra strong‐field ligand such as CO and isocyanide. Hydride donor lithium aluminum hydride (LAH) converted non‐reactive Fe(II) species to reactive Fe(II) hydride species. With this catalyst, various chiral alcohols including the intermediate for montelukast could be prepared with satisfactory yields and enantioinduction. [ABSTRACT FROM AUTHOR]

In this work, the catalytic activity of electronically unsaturated three coordinated aluminum hydride cations [LAlH]+[HB(C6F5)3]− (1) and [LAlH]+[B(C6F5)4]− (2) in hydrosilylation of imines has been disclosed (L={(2,6‐iPr2C6H3N)P(Ph2)}2N). A variety of organo‐silanes such as Et3SiH, MePhSiH2, PhSiH3, TMDSO, and PHMS are screened in this endeavour. The amines as products of catalysis were obtained in good to excellent yields after the hydrolysis of silylamine intermediates. Further, a series of controlled experiments systematically designed to investigate the underlying mechanistic pathway through multinuclear NMR analysis showed Lewis adduct formation between cationic aluminum centre and the imine nitrogen, which subsequently undergoes reaction with silane to afford the product. The hydrosilylation of imine performed with Et3SiH using catalyst 1 with a loading of 2 mol % at 60 °C occurs smoothly. Whereas 2 led to the product formation with Et3SiH only when used in stoichiometric quantity. Further, to investigate this unique behaviour of 1 NMR investigations were performed and revealed that the anion in 1 competes for hydride delivery and in‐situ generates B(C6F5)3 that cooperatively reinforces the catalytic activity of 1. [ABSTRACT FROM AUTHOR]

In the quest for developing rechargeable aluminum (Al) batteries, reversible Al plating in the absence of active‐halide components is considered an immense challenge. For this reason, the choice of electrolyte has been primarily limited to the highly corrosive chloroaluminate systems based on aluminum trichloride (AlCl3). In this work, we demonstrate reversible room‐temperature Al plating from an active‐halide‐free (AHF) organic electrolyte based on aluminum trifluoromethanesulfonate (Al(OTF)3) and lithium aluminum hydride (LiAlH4) in tetrahydrofuran (THF), as well as its AlCl3 counterpart. From insights obtained by Density Functional Theory (DFT) and Fourier‐Transform Infrared (FTIR) spectroscopy, ionic speciation in the electrolyte is explored, and mechanisms for the underlying electrochemical processes in the trifluoromethanesulfonate (OTF−)‐based electrolytes are proposed. Al plating and stripping were confirmed by optical microscopy, scanning electron microscopy (SEM) and X‐ray diffraction (XRD). Characterizing the Al deposits from either the OTF−‐ or the chloride (Cl−)‐based electrolytes via depth‐profile X‐ray Photoelectron Spectroscopy (XPS) analyses, we find that these deposits consist of metallic Al, aluminum oxide (Al2O3), and either aluminum trifluoride (AlF3) or aluminum chloride (AlxCly) contaminants arising from a reaction with the electrolyte components which occurs during the plating process. [ABSTRACT FROM AUTHOR]

Highly combustible elements like beryllium, lithium, Al, Mg, and Zn have the highest combustion, increasing the heat in explosives and propellants. Al can be used because of its greater availability. Reducing the size of Al nanoparticle (NP) increases the combustion rate and decreases the combustion time. This paper studied the effect of initial conditions on the phase transition (PT) and atomic stability times of Fe-coated-aluminium hydride (AlH3) NPs. The molecular dynamics (MD) technique was used in this research. The microscopic behavior of structures was studied by density (Den.), velocity (Vel.), and temperature (Tem.) profiles. Heat flux (HF), PT, and the atomic stability of the structure were examined at different initial pressures (IP) and initial temperatures (IT). According to the achieved results, Den., Vel., and Tem. values had a maximum value of 0.025 atoms/Å3, 0.026 Å/ps, and 603 K. By increasing IT in the simulation box to 350 K, HF in the samples increases to 75.31 W/m2. Moreover, the PT time and atomic stability time by increasing IP reach to 5.93 ns and 8.96 ns, respectively. Regarding the importance of the phenomenon of heat transfer and PT of nanofluids (NFs), the findings of this study are predicted to be useful in various industries, including medicine, agriculture, and others.

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Reduction of a range of amido‐ and aryloxy‐aluminum dihydride complexes, e.g. [AlH2(NR3){N(SiMe3)2}] (NR3=NMe3 or N‐methylpiperidine (NMP)), with β‐diketiminato dimagnesium(I) reagents, [{(ArNacnac)Mg}2] (ArNacnac=[HC(MeCNAr)2]−, Ar=mesityl (Mes) or 2,6‐xylyl (Xyl)), have afforded deep red mixed valence aluminum hydride cluster compounds, [Al6H8(NR3)2{Mg(ArNacnac)}4], which have an average Al oxidation state of +0.66, the lowest for any well‐defined aluminum hydride compound. In the solid‐state, the clusters are shown to have distorted octahedral Al6 cores, having zero‐valent Al axial sites and mono‐valent AlH2− equatorial units. Several novel by‐products were isolated from the reactions that gave the clusters, including the Mg−Al bonded magnesio‐aluminate complexes, [(ArNacnac)(Me3N)Mg−Al(μ‐H)3[{Mg(ArNacnac)}2(μ‐H)]]. Computational analyses of one aluminum hydride cluster revealed its Al6 core to be electronically delocalized, and to possess one unoccupied, and six occupied, skeletal molecular orbitals. [ABSTRACT FROM AUTHOR]

Reduction of a range of amido‐ and aryloxy‐aluminum dihydride complexes, e.g. [AlH2(NR3){N(SiMe3)2}] (NR3=NMe3 or N‐methylpiperidine (NMP)), with β‐diketiminato dimagnesium(I) reagents, [{(ArNacnac)Mg}2] (ArNacnac=[HC(MeCNAr)2]−, Ar=mesityl (Mes) or 2,6‐xylyl (Xyl)), have afforded deep red mixed valence aluminum hydride cluster compounds, [Al6H8(NR3)2{Mg(ArNacnac)}4], which have an average Al oxidation state of +0.66, the lowest for any well‐defined aluminum hydride compound. In the solid‐state, the clusters are shown to have distorted octahedral Al6 cores, having zero‐valent Al axial sites and mono‐valent AlH2− equatorial units. Several novel by‐products were isolated from the reactions that gave the clusters, including the Mg−Al bonded magnesio‐aluminate complexes, [(ArNacnac)(Me3N)Mg−Al(μ‐H)3[{Mg(ArNacnac)}2(μ‐H)]]. Computational analyses of one aluminum hydride cluster revealed its Al6 core to be electronically delocalized, and to possess one unoccupied, and six occupied, skeletal molecular orbitals. [ABSTRACT FROM AUTHOR]

Dearomatized 1,4‐dihydropyridyl motifs are significant in both chemistry and biology for their potential abilities to deliver the stored hydride, driven by rearomatization. Biological cofactors like nicotinamide adenine dinucleotide (NADH) and organic 'hydride sources' like Hantzsch esters are prime examples. An organoaluminum chemistry on a 2‐anilidomethylpyridine framework is reported, where such hydride storage and transfer abilities are displayed by the ligand's pyridyl unit. The pyridylmethylaniline proligand (NNLH) is simultaneously deprotonated and 1,4‐hydroaluminated by AlH3(NMe2Et) to [(NNLde)AlH(NMe2Et)] (1; NNLde=hydride‐inserted dearomatized version of NNL). A hydride abstraction by B(C6F5)3 rearomatizes the pyridyl moiety to give the cationic aluminum hydride [(NNL)AlH(NMe2Et)][HB(C6F5)3] (6). Notably, such chemical non‐innocence is priorly unseen in this established ligand class. The hydroalumination mechanism is investigated by isolating the intermediate [(NNL)AlH2] (2) and by control experiments, and is also analyzed by DFT calculation. The results advocate an intriguing 'self‐promoting' pathway, which underlines alane's Lewis acid/Brønsted base duality. NMe2Et carrying the alane also plays a crucial role. In contrast, the chemistry between NNLH and AlMe3 is much different, giving only [(NNL)AlMe2] (4) from the adduct [(NNLH)AlMe3] (3) by deprotonation but not a subsequent pyridyl dearomatization in the presence or absence of NMe2Et. This divergence is also justified by DFT analyses. [ABSTRACT FROM AUTHOR]

We report two bifunctional (pyridyl)carbene-iridium(I) complexes that catalyze ketone and aldehyde hydrogenation at ambient pressure. Aryl, heteroaryl, and alkyl groups are demonstrated, and mechanistic studies reveal an unusual polarization effect in which the rate is dependant of proton, rather than hydride, transfer. This method introduces a convenient, waste-free alternative to traditional borohydride and aluminum hydride reagents. [ABSTRACT FROM AUTHOR]

Functional liquid fluoroelastomers are in high demand in new energy fields. And these materials have potential applications in high-performance sealing materials and as electrode materials. In this study, a novel high-performance hydroxyl-terminated liquid fluoroelastomer (t-HTLF) with a high fluorine content, temperature resistance, and curing efficiency was synthesised from a terpolymer of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), and hexafluoropylene (HFP). A carboxyl-terminated liquid fluoroelastomer (t-CTLF) with controllable molar mass and end-group content was first prepared from a poly(VDF-ter-TFE-ter-HFP) terpolymer using a unique oxidative degradation method. Subsequently, an efficient "one-step" reduction of the carboxyl groups (COOH) in t-CTLF into hydroxyl groups (OH) was achieved via the functional-group conversion method using lithium aluminium hydride (LiAlH4) as the reductant. Thus, t-HTLF with a controllable molar mass and end-group content and highly active end groups was synthesised. Owing to the efficient curing reaction between OH and isocyanate groups (NCO), the cured t-HTLF exhibits good surface properties, thermal properties, and chemical stability. The thermal decomposition temperature (Td) of the cured t-HTLF reaches 334 °C, and it exhibits hydrophobicity. The oxidative degradation, reduction, and curing reaction mechanisms were also determined. The effects of solvent dosage, reaction temperature, reaction time, and ratio of the reductant to the COOH content on the carboxyl conversion were also systematically investigated. An efficient reduction system comprising LiAlH4 can not only achieve an efficient conversion of the COOH groups in t-CTLF to OH groups but also the in situ hydrogenation and addition reactions of residual double bonds (C=C) groups in the chain, such that the thermal stability and terminal activity of the product are improved while maintaining a high fluorine content. [ABSTRACT FROM AUTHOR]

Amines are one of the most important functional groups in organic synthesis, particularly in scaffolds constituting the active ingredients of natural products, pharmaceutical molecules, and agrochemicals. Among various transformations to access amines, amide reduction has been considered as the most facile and efficient strategy, but it is also one of the most problematic, often requiring the use of highly reactive stoichiometric reductants, such as lithium aluminum hydride, as well as rare transition metal catalysts, or both, and harsh reaction conditions. This review covers recent advances in the catalytic reduction of amides to amines without the need for metal catalysts, thus overcoming such problems. [ABSTRACT FROM AUTHOR]

The alkylation of (4-fluorophenyl)acetonitrile with dibrompentane and 2,2'-dichlorodiethyl ether gave the corresponding nitriles, which were reduced with lithium aluminium hydride to obtain [1-(4-fluorophenyl)cyclohexyl]- and [1-(4-fluorophenyl)tetrahydro-2H-pyran-4-yl]methanamines. Treatment of the latter products with aryloxymethyloxiranes substituted in the aromatic ring resulted in the synthesis of. Some of the synthesized aryloxypropanolamines were transformed into the corresponding oxazolidines under the action of formalin. [ABSTRACT FROM AUTHOR]

A novel methodology has been developed to afford 1,4,5-trisubstituted 1-benzyl-5-formyl-1,2,3-triazole-4-carboxylates in one step under mild conditions. This method includes the reduction of the ester functional group to an aldehyde using lithium tri-tert-butoxyaluminum hydride. Especially, this method offers a different perspective for fully substituted 1,2,3-triazoles with high regioselectivity and high yields. The structure of fully substituted triazoles was verified using FTIR, 1H, 13C NMR spectroscopy, HRMS, advanced NMR techniques (COSY, C-APT, HSQC, and HMBC), and X-ray crystallography. [ABSTRACT FROM AUTHOR]

Alkenes that normally do not react with LiAlH4 (3‐hexene, cyclohexene, 1‐Me‐cyclohexene), can be reduced to the corresponding alkanes by a mixture of LiAlH4 and Fe0 (the iron was activated by Metal‐Vapour‐Synthesis). This alkene‐to‐alkane conversion with a stoichiometric quantity of LiAlH4/Fe0 does not need quenching with water or acids, implying that both H's originate from LiAlH4. The LiAlH4/Fe0 combination is also a remarkably potent cooperative catalyst for hydrogenation of multi‐substituted alkenes and benzene or toluene. An induction period of circa two hours and the minimally required temperature of 120 °C, suggests that the actual catalyst is a combination of Fe0 and the decomposition product of LiAlH4 (LiH and Al0). A thermally pre‐activated LiAlH4/Fe0 catalyst did not need an induction time and is also active at room temperature and 1 bar H2. A combination of AliBu3 and Fe0 is an even more active hydrogenation catalyst. Without pre‐activation, tetra‐substituted alkenes like Me2C=CMe2 and toluene could be fully hydrogenated. [ABSTRACT FROM AUTHOR]

Given its significant gravimetric hydrogen capacity advantage, lithium alanate (LiAlH4) is regarded as a suitable material for solid-state hydrogen storage. Nevertheless, its outrageous decomposition temperature and slow sorption kinetics hinder its application as a solid-state hydrogen storage material. This research's objective is to investigate how the addition of titanium silicate (TiSiO4) altered the dehydrogenation behavior of LiAlH4. The LiAlH4–10 wt% TiSiO4 composite dehydrogenation temperatures were lowered to 92 °C (first-step reaction) and 128 °C (second-step reaction). According to dehydrogenation kinetic analysis, the TiSiO4-added LiAlH4 composite was able to liberate more hydrogen (about 6.0 wt%) than the undoped LiAlH4 composite (less than 1.0 wt%) at 90 °C for 2 h. After the addition of TiSiO4, the activation energies for hydrogen to liberate from LiAlH4 were lowered. Based on the Kissinger equation, the activation energies for hydrogen liberation for the two-step dehydrogenation of post-milled LiAlH4 were 103 and 115 kJ/mol, respectively. After milling LiAlH4 with 10 wt% TiSiO4, the activation energies were reduced to 68 and 77 kJ/mol, respectively. Additionally, the scanning electron microscopy images demonstrated that the LiAlH4 particles shrank and barely aggregated when 10 wt% of TiSiO4 was added. According to the X-ray diffraction results, TiSiO4 had a significant effect by lowering the decomposition temperature and increasing the rate of dehydrogenation of LiAlH4 via the new active species of AlTi and Si-containing that formed during the heating process. [ABSTRACT FROM AUTHOR]

Complex aluminum hydrides with high hydrogen capacity are among the most promising solid-state hydrogen storage materials. The present study determines the thermal stability, hydrogen dissociation energy, and electronic structures of alkali metal aluminum hydrides, MAlH4 (M = Li, Na, K, and Cs), using first-principles density functional theory calculations in an attempt to gain insight into the dehydrogenation mechanism of these hydrides. The results show that the hydrogen dissociation energy (Ed-H2) of MAlH4 (M = Li, Na, K, and Cs) correlates with the Pauling electronegativity of cation M (χP); that is, the Ed-H2 (average value) decreases, i.e., 1.211 eV (LiAlH4) < 1.281 eV (NaAlH4) < 1.291 eV (KAlH4) < 1.361 eV (CsAlH4), with the increasing χP value, i.e., 0.98 (Li) > 0.93 (Na) > 0.82 (K) > 0.79 (Cs). The main reason for this finding is that alkali alanate MAlH4 at higher cation electronegativity is thermally less stable and held by weaker Al-H covalent and H-H ionic interactions. Our work contributes to the design of alkali metal aluminum hydrides with a favorable dehydrogenation, which is useful for on-board hydrogen storage. [ABSTRACT FROM AUTHOR]

Simple synthetic routes to regioselectively deuterated tris[2‐(dimethylamino)ethyl]amine (Me6TREN) variants are described. Imine formation with formaldehyde‐d2 from tris(2‐aminoethyl)amine (TREN) and subsequent reductions with NaBD4 afforded N[CH2CH2N(CD3)2]3 or d18‐Me6TREN in 79 % yield. A trisubstitution protocol from 2‐bromo‐N,N‐dimethylacetamide and ammonium carbonate and subsequent reduction of the N(CH2CONMe2)3 intermediate by lithium aluminum deuteride has afforded N[CH2CD2N(CH3)2]3 or (d6‐arm)‐Me6TREN in three steps and 52 % overall yield. A similar protocol from 2‐bromo‐N,N‐dimethyl‐d2‐acetamide, obtained in two steps from d4‐acetic acid, with reduction of the N(CD2CONMe2)3 intermediate by lithium aluminum hydride has afforded N[CD2CH2N(CH3)2]3 or (d6‐cap)‐Me6TREN in four steps and 13 % overall yield from CD3COOD. [ABSTRACT FROM AUTHOR]

The title compound, [Al4(CH3)8(C2H7N)2H2], crystallizes as eight‐membered rings with –(CH3)2Al–(CH3)2N–(CH3)2Al– moieties connected by single hydride bridges. In the X‐ray structure, the ring has a chair conformation, with the hydride H atoms being close to the plane through the four Al atoms. An optimized structure was also calculated by all‐electron density functional theory (DFT) methods, which agrees with the X‐ray structure but gives a somewhat different geometry for the hydride bridge. Charges on the individual atoms were determined by valence shell occupancy refinements using MoPro and also by DFT calculations analyzed by several different methods. All methods agree in assigning a positive charge to the Al atoms, negative charges to the C, N, and hydride H atoms, and small positive charges to the methyl H atoms. [ABSTRACT FROM AUTHOR]

N-heterocyclic carbenes (NHCs) are widely used in organometallic chemistry. Here, we examine the role of NHCs in the stabilisation of aluminium hydrides, AlH3, also known as alanes. This includes an assessment of the various synthetic strategies, comparisons of structural parameters and theoretical insight. Based on percent buried volume (%Vbur) parameters, we report the largest and smallest NHC alanes to date, with noted differences in their observed stability in both the solution and solid state. [ABSTRACT FROM AUTHOR]

We investigated an electrochemical C−O bond formation approach to (±)‐physovenine. The reaction conditions are mild compared to canonical routes, which typically utilize strong hydride reagents such as lithium aluminum hydride. This enabled extension of the electrochemical cyclization to a substrate bearing the fully functionalized phenyl ring of the natural product. The electrochemical cyclization is diastereoselective and starting from enantiopure substrate would provide a single enantiomer of physovenine. In the course of an initial formal synthesis, we identified conditions to afford modest enantioselective substrate synthesis that demonstrate the feasibility of an enantioselective synthesis. Among the substrates investigated, acetyl‐, tosyl‐ or Boc‐nitrogen substitution led to an alternative electrochemical C−O bond formation pathway where the hydroxyl nucleophile cyclized onto the aromatic ring vs. the 2‐position of the indoline. This work expands the utility of electrochemical C−O bond formation and provides a foundation for further applications to functionalized cyclic ether construction. [ABSTRACT FROM AUTHOR]

The one‐pot synthesis of β,γ‐unsaturated ketones bearing all‐carbon quaternary centers at the α‐position via a highly regioselective hydroacylation of allenes using acyl chlorides and aluminum hydride is reported. The Cu‐catalyzed hydroalumination of 1,1‐disubstituted and 1,1,3‐trisubstituted allenes with diisobutylaluminum hydride resulted in allylaluminum reagents that underwent regioselective acylation in the presence of acid chlorides. Various derivatives of allenes and acyl chlorides were compatible with this process, and α‐quaternary ketones were obtained in high yields with excellent regioselectivity. [ABSTRACT FROM AUTHOR]

The regularities of the reduction of unsaturated nitriles containing the 2-adamantyl fragment with lithium aluminum hydride and nickel—aluminum alloy were studied. In both cases, the double bond and nitrile group were simultaneously reduced. The presence of bulky substituents in the substrate in the α-position to the adamantyl fragment and hydroxy groups significantly retards the process, and the 80–90% yield of the corresponding products is achieved only when the temperature is raised to 65 °C. In the case of using a nickel—aluminum alloy, its 4—6-fold excess is required. The calculation of the potential pharmacological activity of the synthesized compounds shows that they can have antiviral, analgesic, and antidiabetic activity. [ABSTRACT FROM AUTHOR]

Solid-state metal hydrides are prime candidates to replace compressed hydrogen for fuel cell vehicles due to their high volumetric capacities. Sodium aluminum hydride has long been studied as an archetype for higher-capacity metal hydrides, with improved reversibility demonstrated through the addition of titanium catalysts; however, atomistic mechanisms for surface processes, including hydrogen desorption, are still uncertain. Here, operando and ex situ measurements from a suite of diagnostic tools probing multiple length scales are combined with ab initio simulations to provide a detailed and unbiased view of the evolution of the surface chemistry during hydrogen release. In contrast to some previously proposed mechanisms, the titanium dopant does not directly facilitate desorption at the surface. Instead, oxidized surface species, even on well-protected NaAlH4 samples, evolve during dehydrogenation to form surface hydroxides with differing levels of hydrogen saturation. Additionally, the presence of these oxidized species leads to considerably lower computed barriers for H2 formation compared to pristine hydride surfaces, suggesting that oxygen may actively participate in hydrogen release, rather than merely inhibiting diffusion as is commonly presumed. These results demonstrate how close experiment-theory feedback can elucidate mechanistic understanding of complex metal hydride chemistry and potentially impactful roles of unavoidable surface impurities.

Lithium aluminum hydride (LiAlH4) is considered as a promising hydrogen storage material due to its high gravimetric hydrogen storage density. However, sluggish hydrogen kinetics and poor reversibility have prevented its use in practical applications. Improvements of the hydrogen properties of LiAlH4 have been proposed through a nanostructuring approach of the material. Herein, we developed a method to encapsulate freestanding LiAlH4 nanoparticles within a Ti shell upon reduction of TiCl3 at their surface. The LiAlH4@Ti core–shell nanostructures obtained through precise control in the reduction kinetics and the concentration of the Ti precursor led to a significant improvement in the dehydrogenation temperatures and desorption kinetics. Indeed, 5.8 mass % of hydrogen was released within 25 min at 150 °C from LiAlH4@Ti. More remarkably, the formation of the core–shell structure led to the disappearance of the well known exothermic decomposition path of LiAlH4, which evidenced the possibility of altering the hydrogen thermodynamics of LiAlH4. Partial hydrogen reversibility was observed at 150 °C and a 10 MPa hydrogen pressure, mainly because of the loss of the core–shell structure upon hydrogen cycling. However, this demonstrates that with finer control over the nanostructuring of LiAlH4, practical hydrogen storage conditions are within reach. [ABSTRACT FROM AUTHOR]

Limonin is a natural compound which is rich in the fruit of various plants of the Rutaceae family and demonstrated to have a wide range of biological activities. In this work, seven limonin derivatives were successfully synthesized by hydrogenation of limonin, using different reducing agents (sodium cyanoborohydride, lithium aluminum hydride, and sodium borohydride). The chemical structure of the seven derivatives was characterized and identified by a series of techniques, including HR-ESI-MS, 1H-NMR, 13C-NMR, 2D-NMR, and IR. Among the seven limonin derivatives, six limonin derivatives were found to be new compounds which have not been previously reported. Then, the anti-inflammatory activities of the seven synthesized limonin derivatives, as well as the anti-inflammatory activities of eight known natural limonins, were evaluated and compared. Natural limonins, 30-O-Acetylhainangranatumin E and Xylogranatin A, presented significantly better anti-inflammatory activity. Xylogranatin A could inhibit LPS-induced RAW264.7 cell inflammatory factors, with a 90.0% inhibition ratio of TNF-α and 63.77% inhibition ratio of NO release in LPS-induced BV2 cells at 10 μM. Other natural limonins showed poor anti-inflammatory activity. In comparison, all the synthetic limonin derivatives showed decent anti-inflammatory activities, with the highest inhibition ratio of TNF-α of 37.8% and inhibition ratio of NO release of 12.5% in LPS-induced BV2 cells at 10 μM. [ABSTRACT FROM AUTHOR]

Despite the application of lithium aluminium hydride (LiAlH4) being hindered by its sluggish desorption kinetics and unfavourable reversibility, LiAlH4 has received special attention as a promising solid-state hydrogen storage material due to its hydrogen storage capacity (10.5 wt.%). In this work, investigated for the first time was the effect of the nanosized cobalt titanate (CoTiO3) which was synthesised via a solid-state method on the desorption behaviour of LiAlH4. Superior desorption behaviour of LiAlH4 was attained with the presence of a CoTiO3 additive. By means of the addition of 5, 10, 15 and 20 wt.% of CoTiO3, the initial desorption temperature of LiAlH4 for the first stage was reduced to around 115–120 °C and the second desorption stage was reduced to around 144–150 °C, much lower than for undoped LiAlH4. The LiAlH4-CoTiO3 sample also presents outstanding desorption kinetics behaviour, desorbing hydrogen 30–35 times faster than undoped LiAlH4. The LiAlH4-CoTiO3 sample could desorb 3.0–3.5 wt.% H2 in 30 min, while the commercial and milled LiAlH4 desorbs <0.1 wt.% H2. The apparent activation energy of the LiAlH4-CoTiO3 sample based on the Kissinger analysis was decreased to 75.2 and 91.8 kJ/mol for the first and second desorption stage, respectively, lower by 28.0 and 24.9 kJ/mol than undoped LiAlH4. The LiAlH4-CoTiO3 sample presents uniform and smaller particle size distribution compared to undoped LiAlH4, which is irregular in shape with some agglomerations. The experimental results suggest that the CoTiO3 additive promoted notable advancements in the desorption performance of LiAlH4 through the in situ-formed AlTi and amorphous Co or Co-containing active species that were generated during the desorption process. [ABSTRACT FROM AUTHOR]

An unprecedented conjugated bis‐guanidinate (CBG) stabilized aluminium dihydride, [LAlH2; (L={(ArNH)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et2‐C6H3)] (I) catalyzed chemoselective hydroboration of heteroallenes such as carbodiimide (CDI)s, isocyanates, isothiocyanates, and isoselenocyanates is reported. A wide range of heteroallenes, including electron‐donating and withdrawing groups, experience hydroboration to obtain selectively N‐boryl amide, N‐borylaminal, and N‐boryl methyl amine products. More importantly, a single sustainable molecular aluminium‐based catalyst effectively catalyzes CDIs, isocyanates, isothiocyanates, and isoselenocyanates into formamidines, formamides, thioformamides, and selenoformamides, respectively. Further, heteroallene substrates undergo hydrodeoxygenation (HDO), hydrodesulfurization (HDS), and hydrodeselenization (HDSe) reactions leading to N‐boryl methyl amines. In addition, a series of control and kinetic experiments indicate that the aluminium hydride species are essential for all partial and complete reduction steps and breaking the C=X (X=O, S, and Se) bonds in heteroallenes. [ABSTRACT FROM AUTHOR]

In the current research work, the potential of lithium aluminum hydride (LiAlH4), as an energetic fuel and efficient chlorine scavenger, for improving the performance and reducing the negative environmental impacts of composite solid propellants (CSPs) containing ammonium perchlorate as oxidizer, aluminum as fuel, and hydroxyl-terminated polybutadiene as binder (AP/HTPB/Al) was investigated. Three CSP formulations, i.e., AP/HTPB/Al, AP/HTPB/LiAlH4, and AP/HTPB/LiAlH4 + Al, were prepared and characterized using infrared spectroscopic method, differential scanning calorimeter (DSC), and thermogravimetry. The FTIR results revealed that the introduction of LiAlH4 did not alter the chemical structure of the baseline propellant. DSC measurements demonstrated that the three prepared propellant samples displayed a similar thermal decomposition behavior with an increase in thermal decomposition temperatures as the heating rate increased. In addition, an enhanced heat release was found for the complex metal hydride-based propellant samples compared to the pure aluminum-based propellant. Moreover, the deconvolution of the exothermic process related to the main decomposition of LiAlH4-based propellants highlighted a novel exothermic behavior assigned to the interaction of AP-complete dissociation species and LiAlH4 dehydrogenation products. Kinetic modeling performed on DSC data determined at various heating rates using isoconversional methods showed a diminution in the activation energy (Ea) of the propellant that contains LiAlH4, thus highlighting its excellent catalytic effect on both decomposition stages of the AP/HTPB/Al propellant. [ABSTRACT FROM AUTHOR]

The article proposes a scheme for producing hydrogen by hydrothermal oxidation of aluminum combined with a technology for recovering the heat of the aluminum oxidation reaction in metal hydride cycles. Metal hydride cycles are used to compress hydrogen to a pressure of 90 MPa and generate electricity. The energy and material balances of the processes are calculated by thermodynamic modeling. Calculations have shown that hydrothermal oxidation of aluminum combined with metal hydride recovery cycles can increase energy carrier efficiency by 14%. [ABSTRACT FROM AUTHOR]

Photo-dimers of 1,5-diethynylanthracene and 1,5-bis[(trimethylsilyl)ethynyl]anthracene, obtained by UV radiation of the monomers, were treated with the bulky aluminium hydride [(SiMe3)2HC]2AlH in hydroalumination reactions. Hydroalumination of the tetraethynyl-substituted anthracene photo-dimers (syn and anti) led to fourfold aluminium-functionalized Janus-like products with two aluminium functions on each side oriented towards the same direction. The reactions of the monomeric anthracene derivatives with [(SiMe3)2HC]2AlH afforded semi-flexible bidentate Lewis acids, which are interesting building blocks for molecular chains bearing multiple Lewis-acidic functions. The aluminium-functionalized anti-photo-dimer was treated with various donor molecules to gain insight into its host–guest chemistry. All poly-Lewis acids and their adducts were characterized by X-ray diffraction experiments, multinuclear NMR spectroscopy and by elemental analyses. [ABSTRACT FROM AUTHOR]

We present here an improved procedure for the preparation of the promising antitubercular drug SQ109 that is currently in phase Ib/III of clinical trials against Mycobacterium tuberculosis. We investigated and tested the literature synthetic procedure that enables the development of structure–activity relationships and report the observed inconsistencies as well as presenting improvements or novelties for the more efficient preparation of SQ109. Most significantly we applied a novel reduction step of the aminoamide precursor using Me3SiCl­/LiAlH4 under mild conditions. These findings are important for research groups investigating the efficacy of this drug and analogues in academia and industry.

The borane reduction of carbon dioxide bound to aluminum hydrides supported by redox-active acenaphthene-1,2-diimine ligands, [{(dpp-bian)AlO2CH2}2] (1) (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) and [(ArBIG-bian)Al(μ-OC(H)O)2-Li(thf)2] (2) (ArBIG-bian is 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaph-thene), was explored. The reaction of 1 with dimethylaminoborane (1:2) in toluene gives the paramagnetic methoxy-containing aluminum complex [{(dpp-bian)Al(OMe)}2(μ-O)] (3), whereas 2 is inert toward BH3 • NHMe2, but the reduction of 2 with pinacolborane HBpin (1:4) affords the mixed derivative [(ArBIG-bian)Al(OCH3)(OBpin)Li(thf)2] (4). Compounds 3 and 4 were characterized by elemental analysis, EPR and NMR spectroscopy, IR spectroscopy, and X-ray diffraction. The energy parameters of the reaction of 1 with dimethylaminoborane were evaluated and the paramagnetic electronic ground state of molecule 3 was confirmed by quantum chemical calculations. [ABSTRACT FROM AUTHOR]