Search

Ligand exchange processes at metal complexes underpin their reactivity and catalytic applications. While mechanisms of ligand exchange at single site complexes are well established, occurring through textbook associative, dissociative and interchange mechanisms, those involving heterometallic complexes are less well developed. Here we report the reactions of a well‐defined Fe−Al dihydride complex with exogenous ligands (CO and CNR, R=Me, tBu, Xyl=2,6‐Me2C6H3). Based on DFT calculations we suggest that these reactions occur through a dyotropic rearrangement, this involves initial coordination of the exogenous ligand at Al followed by migration to Fe, with simultaneous migration of a hydride ligand from Fe to Al. Such processes are rare for heterometallic complexes. We study the bonding and mechanism of the dyotropic rearrangement through in‐depth computational analysis (NBO, IBOs, CLMO analysis, QTAIM, NCIplot, IGMH), shedding new light on how the electronic structure of the heterometallic core responds to the migration of ligands between metal sites. The dyotropic rearrangement fundamentally changes the nature of the hydride ligands, exposing new nucleophilic reactivity as evidenced by insertion reactions with CO2, isocyanates, as well as isocyanides. [ABSTRACT FROM AUTHOR]

Zirconium alloys are widely used in nuclear water reactors as cladding materials. The cladding materials will absorb hydrogen from high temperature water during the operation of nuclear reactor. In cladding tubes, it has been common sense that circumferential hydrides form without stress, while radial hydrides can form when the hydrides are reoriented under stress loading. In this study, we found that a high heating rate can result in hydride reorientation behavior even without stress. At elevated heating rates, the zirconium alloy clad tube developed a non-uniform strain gradient along the direction of heat conduction. Hydrogen atoms migrate preferentially to areas of elevated stress and precipitate as hydrides that are perpendicular to the direction of tensile stress, resulting in the formation of radial hydrides that appear as "sun spots" macroscopically. Additionally, the high heating rate disrupts the {0001}α∥{111}δ, <11–20>α∥<110>δ orientation relationship between the hydride and the substrate, which potentially facilitates crack propagation. [ABSTRACT FROM AUTHOR]

Because of its current and future intensive use, the synthesis of sustainable ammonia is of major concern. This study focuses on highlighting the mechanistic behaviours of NH3 production from molecular nitrogen and hydrogen on ruthenium materials supported on cerium‐based ternary intermetallics. An interesting activity is reported for Ru/CeTX materials (T=Sc, Ti; X=Si, Ge) with an ammonia production rate around 0.60 mmolNH3 h−1 g−1 at only 300 °C and 1 bar. While the activity at 400 °C appeared attributable to the N≡N cleavage activation, this low‐temperature activity is no longer correlated with this parameter, but rather to the behaviour regarding hydrogen and especially the ability of cerium‐based intermetallic materials to desorb hydrogen from the structure, supporting an associative‐type mechanism. [ABSTRACT FROM AUTHOR]

Achieving superconductivity at room temperature (RT) is a holy grail in physics. Recent discoveries on high‐Tc superconductivity in binary hydrides H3S and LaH10 at high pressure have directed the search for RT superconductors to compress hydrides with conventional electron–phonon mechanisms. Here, an exceptional family of superhydrides is predicated under high pressures, MH12 (M = Mg, Sc, Zr, Hf, Lu), all exhibiting RT superconductivity with calculated Tcs ranging from 313 to 398 K. In contrast to H3S and LaH10, the hydrogen sublattice in MH12 is arranged as quasi‐atomic H2 units. This unique configuration is closely associated with high Tc, attributed to the high electronic density of states derived from H2 antibonding states at the Fermi level and the strong electron–phonon coupling related to the bending vibration of H2 and H‐M‐H. Notably, MgH12 and ScH12 remain dynamically stable even at pressure below 100 GPa. The findings offer crucial insights into achieving RT superconductivity and pave the way for innovative directions in experimental research. [ABSTRACT FROM AUTHOR]

The poor cyclic stability of AB 3 alloys restricts its application in Nickel/Metal hydride batteries. In this work, a new strategy based on phase structure stability and subunit volume regulation is proposed to improve their cyclic stability. The strategy proposes alloys satisfying the three factors may exhibits good cyclic stability: good phase structure stability, [AB 5 ] subunit volume less than 88.3 ų and the [A 2 B 4 ] subunit volume less than 89.2 ų, and the volumes difference of [A 2 B 4 ] and [AB 5 ] subunits less than 5.3 ų. Experimental validation with La 3-x Y x Ni 9 (x = 2.0, 2.6, 3.0) confirms the strategy's feasibility. While the [AB 5 ] subunit volume less than 88.3 ų and the [A 2 B 4 ] subunit volume less than 89.2 ų, the smaller the volume difference of subunits, the better the cyclic stability. La 0.4 Y 2.6 Ni 9 alloy has excellent comprehensive hydrogen storage performance, retaining 80.3% capacity after 130 cycles, much higher than the LaY 2 Ni 9 's 78.2% retention after 50 cycles. [Display omitted] • Strategies are proposed to design AB 3 alloys with long de/hydriding cycle life. • Strategies include phase structure stability, subunit volume and their difference. • La–Y–Ni phase diagram is used to select alloy composition of stable AB 3 structure. • La 0.4 Y 2.6 Ni 9 alloy exhibits good kinetic stability and best cyclic stability. • The mechanism of good cyclic stability is revealed by crystal structure analysis. [ABSTRACT FROM AUTHOR]

The ability to fabricate bimetallic clusters with atomic precision offers promising prospects for elucidating the correlations between their structures and properties. Nevertheless, achieving precise control at the atomic level in the production of clusters, including the quantity of dopant, characteristic of ligands, charge state of precursors, and structural transformation, have remained a challenge. Herein, we report the synthesis, purification, and characterization of a new bimetallic hydride cluster, [AuCu11(H){S2P(OiPr)2}6(C≡CPh)3] (AuCu11H). The hydride position in AuCu11H was determined using DFT calculations. AuCu11H comprises a ligand-stabilized defective fcc Au@Cu11 cuboctahedron. AuCu11H is metastable and undergoes a spontaneous transformation through ligand exchange into the isostructural [AuCu11(Cl){S2P(OiPr)2}6(C≡CPh)3] (AuCu11Cl) and into the complete cuboctahedral [AuCu12{S2P(OiPr)2}6(C≡CPh)4]+ (AuCu12) through an increase in nuclearity. These structural transformations were tracked by NMR and mass spectrometry. [ABSTRACT FROM AUTHOR]

Sr4Ba3(BO3)3.83H2.5, as the second compound to combine borate and hydride ions, has been synthesized by a mechanochemical synthesis route. The structure has been elucidated by synchrotron X‐ray and neutron diffraction and determined to crystallize in the non‐centrosymmetric space group P63mc (186) with the cell parameters a=10.87762(15) Å and c=6.98061(11) Å. A detailed investigation of the compound by vibrational spectroscopy in combination with Density Functional Theory calculations reveals the disordered nature of the structure and proves the presence of both borate and hydride ions. Electronic band structure calculations predict a large band gap of 7.1 eV. Hydride states are predicted at the topmost valence band, which agrees well with earlier reported heteroanionic hydrides. We hereby were able to successfully apply previously synthetic and analytical schemes to introduce another member of the rare compounds that contain complex oxoanions simultaneously with hydride ions. [ABSTRACT FROM AUTHOR]

The efficient synthesis of a N,N'‐bis(2,6‐terphenyl) substituted N‐heterocyclic carbene (NHC) is reported. The gain in efficiency and total yield, compared to traditional synthesis, is the result of a high yielding and scalable double Suzuki coupling step, affording a 2,6‐terphenyl aniline, catalyzed by a Pd β‐diketiminate complex. A stereoelectronic study revealed the new NHC to be very similar to the only other N,N'‐bis(2,6‐terphenyl) substituted NHC. Application to the stabilization of Group 13 trihydrides gives acceptable outcomes but inferior to those observed when the bulky IPr* NHC is deployed. [ABSTRACT FROM AUTHOR]

This work deals with the issue of the deterioration of the mechanical properties of metallic materials (on an example of Ti) in the presence of hydrogen (hydrogen embrittlement). Three main forms of fracture caused by the presence of hydrogen in metallic materials are distinguished. The first one is the damage in internal pores and cracks, which appear when bubbles of gaseous hydrogen are trapped during melt solidification or hydrogen diffusion through the metal lattice. The second one is associated with hydrogen that forms hydrides and changes the type of crystal lattice of the metal. The third one includes other types of fracture associated with hydrogen in the bulk material under long-term static loads. The main methods of preventing the interaction of metallic materials with hydrogen are determined as follow: (i) alloying that reduces the rate of interaction of the metal material with hydrogen, (ii) surface modification by methods of high-energy impact, (iii) application of protective coatings, and (iv) heat treatment of final products.

The recent theory-driven discovery of a class of clathrate hydrides (e.g., CaH6, YH6, YH9, and LaH10) with superconducting critical temperatures (T) well above 200 K has opened the prospects for "hot" superconductivity above room temperature under pressure. Recent efforts focus on the search for superconductors among ternary hydrides that accommodate more diverse material types and configurations compared to binary hydrides. Through extensive computational searches, we report the prediction of a unique class of thermodynamically stable clathrate hydrides structures consisting of two previously unreported H24 and H30 hydrogen clathrate cages at megabar pressures. Among these phases, LaSc2H24 shows potential hot superconductivity at the thermodynamically stable pressure range of 167 to 300 GPa, with calculated Tcs up to 331 K at 250 GPa and 316 K at 167 GPa when the important effects of anharmonicity are included. The very high critical temperatures are attributed to an unusually large hydrogen-derived density of states at the Fermi level arising from the newly reported peculiar H30 as well as H24 cages in the structure. Our predicted introduction of Sc in the La--H system is expected to facilitate future design and realization of hot superconductors in ternary clathrate superhydrides. [ABSTRACT FROM AUTHOR]

This work explores the combination of sterically crowded low‐valent germanium compounds bearing one or two terphenyl (C6H3‐2,6‐Ar2) substituents with gold fragments, the latter stabilized by crowded phosphines also containing a terphenyl moiety. The steric protection of these motifs has allowed to examine a series of unusual gold‐germylene compounds featuring small hydride and methyl substituents at the germanium site. A gold‐germylene dicationic structure is also reported. The bonding in this series is investigated by computational means, providing understanding for the two‐way transfer of electrons from germanium to gold and vice versa. [ABSTRACT FROM AUTHOR]

The traditional Haber-Bosch process for the ammonia synthesis suffers from high energy consumption and severe pollution. Therefore, developing a clean and green synthetic process has been the current research focus. Electrochemical reduction is such a method for nitrogen fixation and ammonia formation, with the core technology lying in how to improve the yield and current efficiency by using proper electrochemical catalysts. Based on literature analysis and summarization, a review was made in this paper on the advances in the ruthenium-based catalysts for the ammonia synthesis, including the synthesis mechanisms from different nitrogen sources, the preparation and modification of ruthenium-based catalysts and their performance. Influence of the catalyst morphology and size on the performance as well as the synergistic effects among ruthenium metal, support, and co-catalysts were also explored, with an aim to provide new perspectives for understanding the ruthenium catalytic process of electrochemical reduction synthesis of ammonia. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In our study, we utilize molecular dynamics simulations, specifically through the Reactive Empirical Bond Order, to unravel atomic-scale dynamics in graphite, an essential component in many advanced technologies, under varying irradiation scenarios. We shed light on the behavior of graphite when exposed to Primary Knock-on Atom (PKA) energies of 10, 20, 40, and 80 keV. The findings highlight the radiation vulnerability of graphite, especially when influenced by hydride inclusion. Both pristine graphite and its hydride variant exhibited an increase in Frenkel pairs (FPs) with escalating PKA energies. Notably, carbon PKAs manifested significant FP effects, whereas hydrogen PKAs influenced defect formation through variable diffusivity. In tested radiation scenarios, particularly in Mode C and the R1 region, cascade patterns identified distinct defect forms of diamond-like and elongated-diamond-like shapes, distinct from the typical PKA collision clusters. Furthermore, our cascade findings emphasize the formation of three-coordinated graphite rings, particularly as PKA energies increase. The graphite population statistics reveal a decline in threefold-coordinated atoms and an increase in other types of defects, with 7-carbon atom rings being the most common. Our research highlights the significance of understanding three-coordinated graphite rings, especially as PKA energies rise. Graphite population statistics reveal a decline in threefold-coordinated atoms and a rise in other defects. Notably, 7-carbon atom rings are the most common. From a clustering perspective, self-interstitial atom (SIA) clusters predominated in pristine graphite, while this trend balanced in the hydride variant. Our research highlights the importance of understanding atomic behaviors in graphite under several radiation scenarios. This knowledge is needed for advancing reliable and efficient technological applications, particularly in the field of nuclear technology. Our research underscores the need to understand atomic behaviors in graphite under radiation, paving the way for detailed study on reliable efficient technological applications. [ABSTRACT FROM AUTHOR]

Abstract Achieving superconductivity at room temperature (RT) is a holy grail in physics. Recent discoveries on high‐Tc superconductivity in binary hydrides H3S and LaH10 at high pressure have directed the search for RT superconductors to compress hydrides with conventional electron–phonon mechanisms. Here, an exceptional family of superhydrides is predicated under high pressures, MH12 (M = Mg, Sc, Zr, Hf, Lu), all exhibiting RT superconductivity with calculated Tcs ranging from 313 to 398 K. In contrast to H3S and LaH10, the hydrogen sublattice in MH12 is arranged as quasi‐atomic H2 units. This unique configuration is closely associated with high Tc, attributed to the high electronic density of states derived from H2 antibonding states at the Fermi level and the strong electron–phonon coupling related to the bending vibration of H2 and H‐M‐H. Notably, MgH12 and ScH12 remain dynamically stable even at pressure below 100 GPa. The findings offer crucial insights into achieving RT superconductivity and pave the way for innovative directions in experimental research.

The bulky β‐diketiminate ligand frameworks [BDIDCHP]− and [BDIDipp/Ar]− (BDI=[HC{C(Me)2N‐Dipp/Ar}2]− (Dipp=2,6‐diisopropylphenyl (Dipp); Ar=2,6‐dicyclohexylphyenyl (DCHP) or 2,4,6‐tricyclohexylphyenyl (TCHP)) have been developed for the kinetic stabilisation of the first europium (II) hydride complexes, [(BDIDCHP)Eu(μ‐H)]2, [(BDIDipp/DCHP)Eu(μ‐H)]2 and [(BDIDipp/TCHP)Eu(μ‐H)]2, respectively. These complexes represent the first step beyond the current lanthanide(II) hydrides that are all based on ytterbium. Tuning the steric profile of β‐diketiminate ligands from a symmetrical to unsymmetrical disposition, enhanced solubility and stability in the solution–state. This provides the first opportunity to study the structure and bonding of these novel Eu(II) hydride complexes crystallographically, spectroscopically and computationally, with their preliminary reactivity investigated. [ABSTRACT FROM AUTHOR]

When zirconium alloy undergoes water corrosion reaction during the service process, it absorbs hydrogen to form brittle hydrides, which is one of the main reasons for the deterioration of the mechanical properties of zirconium alloy. There is an urgent need to find an effective method to regulate brittle hydrides to restore the properties of hydrogen-containing zirconium alloys. This study conducted electropulsing treatment on the hydrogen-charged nuclear grade Zr-4 alloy, and the results showed that the electropulsing process caused the hydrides to transform from large-sized brittle stripe-shaped δ-phase to the small-sized ζ-phase. The hydrogen content in the alloy is significantly reduced, which basically restores the mechanical properties of the alloy. However, in the comparative experiment of isothermal heat treatment at 400 °C, brittle hydrides did not dissolve and their mechanical properties did not recover. A mathematical model was established for the characteristics and morphological changes of strip hydrides, and the current density distribution and introduced free energy during the microstructure evolution process were calculated and analyzed. The calculation results indicate that the pulsed current promotes the decomposition of hydrides through the introduction of free energy, reduces the activation energy of hydrogen atom diffusion, accelerates the diffusion and desorption of hydrogen atoms, and realizes the repair of mechanical properties of hydrogen-charged zirconium alloy. • The regulation of brittle hydride of Zr alloy by pulsed current was studied. • Pulsed current promotes the phase transition of brittle hydrides at lower temperatures. • Pulsed current restores the properties of hydrogen-charged zirconium alloy. • The dissolution temperature and activation energy of hydrides are reduced. [ABSTRACT FROM AUTHOR]

The ternary germanide Mg5.57Ni16Ge7.43 (cubic, space group Fmm, cF116) belongs to the structural family based on the Th6Mn23‐type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three‐core‐shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a coordination number of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three‐core‐shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2. [ABSTRACT FROM AUTHOR]

Ammonia is pivotal to various chemical industries, which is produced using the Haber-Bosch process. This process requires harsh conditions (e.g., 20.0 MPa and (500–600)°C) to generate ammonia and thus, is an energy intensive process. The growing consensus is to mild the conditions for ammonia generation. Herein, we demonstrate the use of hydride to increase the activity of molybdenum carbonitride (MCN). YH@MCN (95:5, w/w) generates ammonia at a rate of 448 μ m o l g − 1 h − 1 at 255 °C and 0.1 MPa. To address the stability issue of hydride, we incorporate iron. The experiment demonstrates two-fold rates for such catalyst, comparing MCN alone. The activation energy (19.73kJmol-1) for YFeH@MCN is considerably low, owing to the electron transfer from YH to MCN that facilitates nitrogen dissociation. Hence, the use of distinct sites for easy dissociation of nitrogen molecules, and the synergy between them, results in an activity that exceeds of conventional molybdenum and iron-based catalysts, and is comparable to ruthenium-based catalysts. Our results illustrate the potential of using synergistic multiple active sites in catalysts, and introduce a design concept for ammonia synthesis catalysts, using readily available elements. • Low-temperature ammonia synthesis is performed using hydrides. • Hydride promotes catalytic activity of molybdenum carbonitride. • Hydrogen storage capacity of yttrium mixed with iron is examined. • YH@MCN generates ammonia at a rate of 448 μ m o l g − 1 h − 1 at 255 °C and 0.1 MPa. • Low activation energy (19.73kJmol-1) infers transfer of electrons from YH to MCN. [ABSTRACT FROM AUTHOR]

Herein, reactivity studies of a cyclic bis‐hydridostannylene [(ADC)SnH]2 (1‐H2) (ADC=PhC{(NDipp)C}2; Dipp=2,6‐iPr2C6H3) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1‐H2 afford mixed acetylide‐vinyl‐functionalized bis‐stannylenes via dehydrogenation and hydrostannylation. Treatment of 1‐H2 with PhC≡CCH3 gives a unique distannabarrelene via dehydrogenative C(sp3)−H stannylation and hydrostannylation of the C≡CCH3 moiety. 1‐H2 undergoes dehydrogenative [2+2]‐cycloaddition reactions with diphenylacetylene, azobenzene, acetone, benzophenone, and benzaldehyde to form the 1,4‐distannabarrelene derivatives. The elimination of H2 in these reactions suggests the masked‐diradical property of 1‐H2. In fact, these [2+2]‐cycloaddition products are also accessible on treatments of the Sn(I) diradicaloid [(ADC)Sn]2 (1) with appropriate reagents. All compounds have been characterized by multinuclear NMR spectroscopy and single crystal X‐ray diffraction. Moreover, the catalytic activity of 1‐H2 has been shown for the hydroboration of unsaturated substrates. [ABSTRACT FROM AUTHOR]

Recently, surface‐hopping ab initio molecular dynamics (SH‐AIMD) simulations have come to be used to discuss the mechanisms and dynamics of excited‐state chemical reactions, including internal conversion and intersystem crossing. In dynamics simulations involving intersystem crossing, there are two potential energy surfaces (PESs) governing the motion of nuclei: PES in a spin‐pure state and PES in a spin‐mixed state. The former gives wrong results for molecular systems with large spin‐orbit coupling (SOC), while the latter requires a potential gradient that includes a change in SOC at each point, making the computational cost very high. In this study, we systematically investigate the extent to which the magnitude of SOC affects the results of the spin‐pure state‐based dynamics simulations for the hydride MH2 (M = Si, Ge, Sn, Pb) by performing SH‐AIMD simulations based on spin‐pure and spin‐mixed states. It is clearly shown that spin‐mixed state PESs are indispensable for the dynamics simulation of intersystem crossing in systems containing elements Sn and Pb from the fifth period onward. Furthermore, in addition to the widely used Tully's fewest switches (TFS) algorithm, the Zhu‐Nakamura (ZN) global switching algorithm, which is computationally less expensive, is applied to SH for comparison. The results from TFS‐ and ZN‐SH‐AIMD methods are in qualitative agreement, suggesting that the less expensive ZN‐SH‐AIMD can be successfully utilized to investigate the dynamics of photochemical reactions based on quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Addition of CO to a tetrametallic magnesium hydride cluster results in both carbon‐carbon bond formation and deoxygenation to generate an acetaldehyde enolate [C2OH3]− which remains coordinated to the cluster. To the best of our knowledge, this is the first example of formation of an isolable complex containing an [C2OH3]− fragment from reaction of CO with a metal hydride, and the first example of CO homologation and deoxygenation at a main group metal. DFT studies suggest that key steps in the mechanism involve nucleophilic attack of an oxymethylene on a formyl ligand to generate an unstable [C2O2H3]3− fragment, which undergoes subsequent deoxygenation. [ABSTRACT FROM AUTHOR]

Using first principles density functional theory calculations, the crystal structure, electronic properties, and superconductivity characteristics of the ternary hydride Y-Si-H system under high pressure were investigated. The study revealed the existence of thermodynamically stable phases, including YSiH7, YSiH9, YSi2H12, and YSiH18, and thermodynamically metastable phases, namely YSi2H13, YSi2H14, and Y2SiH17. Electronic properties calculations showed that YSiH7 is insulator and YSi2H13 is semiconductor, while the remaining hydrides exhibit metallic properties. Superconducting transition temperatures (Tc) were estimated using the McMillan equation, with YSi2H12 hosting the highest Tc of 43.5 K at 100 GPa. The dynamic stable pressure of YSi2H14 can be reduced to 40 GPa, and its Tc is 23.8 K which is twice the highest Tc among binary Y-Si compounds, indicating that introducing H atom into Y-Si system can effectively increase the superconducting transition temperature. Y2SiH17 exhibits a Tc of 35.8 K at 100 GPa. Spectral function and electron-phonon coupling calculations suggested that in YSi2H14 and Y2SiH17, in addition to the H-induced superconductivity from mid-frequency vibrations, low-frequency vibrations of Y also play a significant role for superconductivity. [ABSTRACT FROM AUTHOR]

This work deals with the issue of the deterioration of the mechanical properties of metallic materials (on an example of Ti) in the presence of hydrogen (hydrogen embrittlement). Three main forms of fracture caused by the presence of hydrogen in metallic materials are distinguished. The first one is the damage in internal pores and cracks, which appear when bubbles of gaseous hydrogen are trapped during melt solidification or hydrogen diffusion through the metal lattice. The second one is associated with hydrogen that forms hydrides and changes the type of crystal lattice of the metal. The third one includes other types of fracture associated with hydrogen in the bulk material under long-term static loads. The main methods of preventing the interaction of metallic materials with hydrogen are determined as follow: (i) alloying that reduces the rate of interaction of the metal material with hydrogen, (ii) surface modification by methods of high-energy impact, (iii) application of protective coatings, and (iv) heat treatment of final products. [ABSTRACT FROM AUTHOR]

Alkali metal amidoboranes have been intensively investigated as potentially highly attractive candidates for solid-state hydrogen storage. In this family, sodium amidoborane NaNH 2 BH 3 occupies a special place, due to its unique properties. From one side, its high hydrogen content (9.4 wt.%) and low dehydrogenation temperature (89 °C) make it very perspective in this regard. However, detailed studies revealed a number of very serious drawbacks, which consequently led to a dramatic reduction of the initial research hype, although potentially very interesting innovative aspects of its use beyond hydrogen storage have also been discovered. However, a critical insight to the entire field of metal amidoborane chemistry, especially in the technologically relevant context of solid-state hydrogen storage, is lacking. Thus, by this review, we want to fill this gap. Accordingly, this review brings a detailed and critical comparative discussion of synthesis and chemical properties of sodium amidoborane. They are considered not exclusive through technological, but also environmentally relevant optics with respect of their utilization in real-world advanced and sustainable energy systems. [Display omitted] [ABSTRACT FROM AUTHOR]

A structurally precise hydride‐containing Pt‐doped Cu‐rich nanocluster [PtH2Cu14{S2P(OiPr)2}6(CCPh)6] (1) has been synthesized. It consists of a bicapped icosahedral Cu14 cage that encapsulates a linear PtH2 unit. Upon the addition of two equivalents of CF3COOH to 1, two hydrido clusters are isolated. These clusters are [PtHCu11{S2P(OiPr)2}6(CCPh)4] (2), which is a vertex‐missing Cu11 cuboctahedron encaging a PtH moiety, and [PtH2Cu11{S2P(OiPr)2}6(CCPh)3] (3), a distorted 3,3,4,4,4‐pentacapped trigonal prismatic Cu11 cage enclosing a PtH2 unit. The electronic structure of 2, analyzed by Density Functional Theory, is a 2e superatom. The electrocatalytic activities of 1–3 for hydrogen evolution reaction (HER) were compared. Notably, Cluster 2 exhibited an exceptionally excellent HER activity within metal nanoclusters, with an onset potential of −0.03 V (at 10 mA cm−2), a Tafel slope of 39 mV dec−1, and consistent HER activity throughout 3000 cycles in 0.5 M H2SO4. Our study suggests that the accessible central Pt site plays a crucial role in the remarkable HER activity and may provide valuable insights for establishing correlations between catalyst structure and HER activity. [ABSTRACT FROM AUTHOR]

One of the promising intermetallic compounds for use in nuclear and fusion reactors, as well as in hydrogen energy technology, are intermetallic compounds of beryllium with metals such as Ti, V, Zr and Nb. Beryllium-based intermetallics are not only a promising material for blankets of future fusion reactors, but can also be utilized in other areas of the nuclear industry, including fission reactor reflectors, rocket and space technology. The interest in studies of the interaction of hydrogen isotopes with beryllides is related to the accumulation of tritium and helium in the material, formed as a result of nuclear reactions under neutron irradiation, and is caused by the need for understanding the processes arising from such interaction.In this work, hydrogen sorption and desorption processes of zirconium beryllide ZrBe2 produced by industrial technologies at JSC “Ulba Metallurgical Plant” (JSC UMP) were investigated. The experiments were performed by the Sievert’s and thermal desorption spectrometry (TDS) methods. In TDS experiments deuterium was chosen for samples saturation to reduce the possible error in determining fluxes associated with the release of hydrogen from the elements of the vacuum chamber.An equation for hydrogen solubility in zirconium beryllide ZrBe2 was obtained by processing the experimental data obtained by the Sievert’s method:S=0.46±0.1molm3∙Pa12∙exp-13.3±0.5kJmolRTThe temperature intervals of formation and decomposition of two different hydride phases (deuterides) of zirconium beryllide ZrBe2 at ∼ 600 K and ∼ 900 K have been established in TDS experiments.

Zirconium alloys are widely used in nuclear water reactors as cladding materials. The cladding materials will absorb hydrogen from high temperature water during the operation of nuclear reactor. In cladding tubes, it has been common sense that circumferential hydrides form without stress, while radial hydrides can form when the hydrides are reoriented under stress loading. In this study, we found that a high heating rate can result in hydride reorientation behavior even without stress. At elevated heating rates, the zirconium alloy clad tube developed a non-uniform strain gradient along the direction of heat conduction. Hydrogen atoms migrate preferentially to areas of elevated stress and precipitate as hydrides that are perpendicular to the direction of tensile stress, resulting in the formation of radial hydrides that appear as “sun spots” macroscopically. Additionally, the high heating rate disrupts the {0001}α∥{111}δ, α∥δ orientation relationship between the hydride and the substrate, which potentially facilitates crack propagation.

The ability to fabricate bimetallic clusters with atomic precision offers promising prospects for elucidating the correlations between their structures and properties. Nevertheless, achieving precise control at the atomic level in the production of clusters, including the quantity of dopant, characteristic of ligands, charge state of precursors, and structural transformation, have remained a challenge. Herein, we report the synthesis, purification, and characterization of a new bimetallic hydride cluster, [AuCu11(H){S2P(OiPr)2}6(C≡CPh)3] (AuCu11H). The hydride position in AuCu11H was determined using DFT calculations. AuCu11H comprises a ligand-stabilized defective fcc Au@Cu11 cuboctahedron. AuCu11H is metastable and undergoes a spontaneous transformation through ligand exchange into the isostructural [AuCu11(Cl){S2P(OiPr)2}6(C≡CPh)3] (AuCu11Cl) and into the complete cuboctahedral [AuCu12{S2P(OiPr)2}6(C≡CPh)4]+ (AuCu12) through an increase in nuclearity. These structural transformations were tracked by NMR and mass spectrometry.

This study aimed to investigate the impact of hydrogen content, up to 1217 ppm, on the mechanical properties of Zircaloy-4, with a particular focus on the formation and impact of hydrides. Tensile specimens were tested across a range of temperatures and hydrogen concentrations. The results revealed a pronounced ductile-to-brittle transition associated with hydride formation. When the hydrogen content in the specimens ranged between 700 and 850 ppm, a ductile-to-brittle transition was observed at temperatures of 25 °C, 50 °C, and 75 °C. At 25 °C, the ultimate tensile strength (UTS) of Zircaloy-4 linearly increased as the hydrogen concentration rose from 0 to 1217 ppm H. However, at higher temperatures, the behavior of UTS became more complex, especially in the hydrogen concentration ranges of 500–850 ppm H. Elongation (EL) in the hydrided specimens was affected by both temperature and hydrogen concentration. As hydrogen concentration increased, there was a noticeable decline in uniform EL, while non-uniform EL showed even more significant reductions. Scanning electron microscopy (SEM) analysis of the fracture surfaces revealed that quasi-cleavage features became evident when the hydrogen content reached 850 ppm H, across all tested temperatures. These findings not only provide a quantitative assessment of the safety implications of Zircaloy-4 in nuclear reactor applications but also highlight the importance of the hydrogen charging process and mechanical testing in understanding its mechanical behavior. [ABSTRACT FROM AUTHOR]

Die selektive Bildung homonuklearer Bindungen ist in der synthetischen Chemie von zentraler Bedeutung. Insbesondere Dehydrokupplungsreaktionen sind als ökologische und ökonomische Alternativen zu etablierten reduktiven Bindungsbildungsreaktionen attraktiv, da sie nicht den Einsatz stöchiometrischer Mengen eines Reduktionsmittels erfordern und nur wertvollen Wasserstoff als Nebenprodukt erzeugen. Hier berichten wir über eine metallfreie B−B‐Dehydrokupplungsreaktion, die direkt von einem einfachen, leicht zugänglichen BH3‐Addukt startet und einen bequemen Zugang zu einem neuen nukleophilen Dihydridodiboran in exzellenter Ausbeute bietet. Das Dihydridodiboran wiederum aktiviert Wasserstoff, sodass durch D2‐Aktivierung quantitativ das Dideuteridodiboran aus dem Dihydridodiboran erhalten werden kann. Auf Grundlage detaillierter quantenchemischer Berechnungen wird der Mechanismus dieser beispiellosen Reaktion aufgeklärt. Einige für die metallfreie Dehydrokupplung essenzielle Kernpunkte werden aufgezeigt und dadurch der Weg für einen systematischen Zugang und Anwendung bereitet. [ABSTRACT FROM AUTHOR]

Given Fe is a low-cost earth-abundant element, there is a need to develop novel Fe-based metal hydrides. The conventional Fe-based hydrides consist of at least one metal with high hydrogen affinity. To synthesize novel low-affinity Fe-based hydrides, the high-pressure and high-temperature method is currently being used. The microstructure is known to influence the de-/hydrogenation processes in metal hydrides. However, in the context of low-affinity Fe-based hydrides, the role of the initial multi-phase microstructure is unknown, which is the objective of the current work. We investigate three as-cast Fe–Mo binary alloys: Fe 0.33 Mo 0.67 , Fe 0.5 Mo 0.5 , and Fe 0.67 Mo 0.33. Firstly, we first explain in detail the formation mechanisms of the non-equilibrium initial as-cast microstructures caused by the sluggish diffusion of Mo. Subsequently, we present the phase transformations and microstructure evolution during the hydrogenation, depressurization, and aging of Fe–Mo alloys. We demonstrate that each phase in the initial microstructure act as an independent phase during hydrogenation. [Display omitted] • Three Fe–Mo alloys investigated: Fe 0.33 Mo 0.67 , Fe 0.5 Mo 0.5 , and Fe 0.67 Mo 0.33 • Formation mechanisms of non-equilibrium multi-phase initial microstructure reported. • Each initial phase transformed independently during hydrogenation at 6 GPa & 750 °C. • Phase transformations during dehydrogenation and aging have been investigated. • Microstructure dependence of cracking in dehydrogenated and aged samples discussed. [ABSTRACT FROM AUTHOR]

We conducted absorption experiments on Ti using hydrogen isotopes, protium and deuterium, to gain insights into the kinetics of hydrogen atoms, particularly across the Ti surface. Rather than relying on various surface pretreatments, we identified the initial temperature of Ti in vacuum as the determining factor in achieving a high absorption rate and content. Specifically, we found that the initial Ti temperatures of approximately 900 and 980 °C are optimal for protium and deuterium, respectively, likely due to sufficient removal of the native surface oxide on Ti. The dependence of the absorption rate and amount of hydrogen isotopes on the temperature during absorption was partially explained by the phase transformation and exothermicity of the hydrogenation reaction. Moreover, this dependence strongly indicated the existence of a tunneling transport process. Additionally, we developed a kinetic model for hydrogen isotope transport in Ti to conduct numerical simulations. The absorption curves, calculated using the developed model, closely matched a series of experimental curves obtained at different temperatures. These curves were from an identical set of equations and kinetic parameters for both protium and deuterium. Our numerical kinetic model has the potential to serve as a valuable simulation tool for various applications, such as the design of high-performance hydrogen storage systems and maintenance strategies against hydrogen embrittlement of structural materials. • Protium and deuterium absorption experiments in Ti performed. • The initial Ti temperature in vacuum determines high absorption rate and content. • The initial Ti temperatures of 900 (protium) and 980 °C (deuterium) are optimal. • Temperature dependence indicates the existence of tunneling transport process. • A kinetic model of hydrogen isotope transport for numerical simulations presented. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many sub-Neptune exoplanets have been believed to be composed of a thick hydrogen-dominated atmosphere and a high-temperature heavier-element-dominant core. From an assumption that there is no chemical reaction between hydrogen and silicates/metals at the atmosphere-interior boundary, the cores of sub-Neptunes have been modeled with molten silicates and metals (magma) in previous studies. In large sub-Neptunes, pressure at the atmosphere-magma boundary can reach tens of gigapascals where hydrogen is a dense liquid. A recent experiment showed that hydrogen can induce the reduction of Fe2+ in (Mg,Fe)O to Fe0 metal at the pressure-temperature conditions relevant to the atmosphere-interior boundary. However, it is unclear whether Mg, one of the abundant heavy elements in the planetary interiors, remains oxidized or can be reduced by H. Our experiments in the laser-heated diamond-anvil cell found that heating of MgO + Fe to 3,500 to 4,900 K (close to or above their melting temperatures) in an H medium leads to the formation of Mg2FeH6 and H2O at 8 to 13 GPa. At 26 to 29 GPa, the behavior of the system changes, and Mg-H in an H fluid and H2O were detected with separate FeHx. The observations indicate the dissociation of the Mg-O bond by H and subsequent production of hydride and water. Therefore, the atmosphere-magma interaction can lead to a fundamentally different mineralogy for sub-Neptune exoplanets compared with rocky planets. The change in the chemical reaction at the higher pressures can also affect the size demographics (i.e., "radius cliff") and the atmosphere chemistry of sub-Neptune exoplanets. [ABSTRACT FROM AUTHOR]

Experimental results for hydrides reorientation in unirradiated E635 guide tubes are presented. The key parameter for reorientation–the threshold stress was found. Some features of microstructure of hydrides with different orientation are discussed. For cooling rates, which are specific for active zones of pressurized water reactors, δ-hydride is shown to be the only phase that occurs. [ABSTRACT FROM AUTHOR]

The hydrogenation of a mechanical 200-μm mixture of commercial magnesium in the presence of 10–40 wt % Ti2Ni intermetallic compound as a catalytic additive under a high-purity hydrogen pressure of 30 atm and at temperatures of 350–390°C without the use of preliminary high-energy treatment of the reactant mixture has been studied in order to optimize conditions for the hydrogenation of magnesium. It has been found that in a mixture of Mg + 20 wt % Ti2Ni, magnesium is hydrogenated by 95–96% at 370–380°C with a total hydrogen content of 6.2 wt % in the resulting mixture of hydrides. This mixture, as a working substance in reusable high-temperature metal hydride hydrogen batteries at 250–450°C, released high-purity hydrogen (99.999 wt %) for practical use in small-scale and laboratory works. [ABSTRACT FROM AUTHOR]

The method of thermal desorption spectroscopy (TDS) implemented on an automated Gas Reaction Controller LPB complex and the procedure for conducting experiments on the study of hydrogen accumulation using the TDS method are described. The use of the complex made it possible to perform experiments on TDS immediately after saturation with hydrogen without removing the samples from the vacuum environment. The operating temperatures of the complex were in the range from 20 to 1000°C. The heating rate was kept constant and could be set between 0.1°C/min and 6°C/min. The pressure range was from 6 × 10–8 to 1 × 10–5 Pa when performing thermal desorption spectroscopy and from 0.02 Pa to 5 × 103 Pa when the samples were saturated with hydrogen. For the E110 zirconium alloy, the temperature dependence of the sorption rate was determined. Using in situ X-ray diffraction on synchrotron radiation, it was shown that during gas-phase hydrogenation in the E110 zirconium alloy (Zr–1% Nb), δ-hydrides were formed throughout the entire bulk of the material. Under thermal action, the dissociation of hydrides occurred in the temperature range of 500–550°C. With a further increase in temperature, a thermally stimulated release of hydrogen occurred, accompanied by a phase transition of zirconium from the α to the β phase. [ABSTRACT FROM AUTHOR]

The dependence on fossil fuels for energy has culminated in its gradual depletion and this has generated the need to seek alternative source that will be environmentally friendly and sustainable. Hydrogen stands to be promising in this regard as energy carrier which has been proven to be efficient. Magnesium hydride (MgH2) can be used in storing hydrogen because of its availability, light weight and low cost. In this review, monoatomic, alloy, intermetallic and composite forms of Ti, Ni, V, Mo, Fe, Cr, Co, Zr and Nb as additives on MgH2 are discussed. Through ball milling, additive reacts with MgH2 to form compounds including TiH2, Mg2Ni, Mg2NiH4, V2O, VH2, MoSe, Mg2FeH6, NbH and Nb2O5which remain stable after certain de/hydrogenation cycles. Some monoatomic transition metals remain unreacted even after de/hydrogenation cycles. These formed compounds, including stable monoatomic transition metals, impart their catalytic effects by creating diffusion channels for hydrogen via weakening Mg - H bond strength. This reduces hydrogen de/sorption temperatures, activation energies and in turn, hastens hydrogen desorption kinetics of MgH2. Hydrogen storage output of MgH2/transition metal-based materials depend on additive type, ratio of MgH2/additive, ball milling time, ball –to combining materials ratio and de/hydrogenation cycle. There is a need for more investigations to be carried out on nanostructured binary and ternary transition metal-based materials as additives to enhance the hydrogen storage performance of MgH2. In addition, the already established compounds (listed above) formed after ball milling or dehydrogenation can be processed and directly doped into MgH2.

Abstract As the first safety barrier of nuclear reactors, zirconium alloy cladding tubes have attracted extensive attention because of its good mechanical properties. The strength and ductility of zirconium alloy are of great significance to the service process of cladding tubes, while brittle hydrides precipitate and thus deteriorate the overall performance. Based on the cohesive finite element method, the effects of cohesive strength, interfacial characteristics, and hydrides geometric characteristics on the strength and ductility of two-phase material (zirconium alloy with hydrides) are numerically simulated. The results show that the fracture behavior is significantly affected by the cohesive strength and that the overall strength and ductility are sensitive to the cohesive strength of the zirconium alloy. Furthermore, the interface is revealed to have prominent effects on the overall fracture behavior. When the cohesive strength and fracture energy of the interface are higher than those of the hydride phase, fracture initiates in the hydrides, which is consistent with the experimental phenomena. In addition, it is found that the number density and arrangement of hydrides play important roles in the overall strength and ductility. Our simulation provides theoretical support for the performance analysis of hydrogenated zirconium alloys during nuclear reactor operation.

The fracture mechanism of hydrogen charged Ti–6Al–4V has been investigated through a multianalytical approach. The difference in hydrogen solubility between β phase (high solubility) and α phase (low) governs the formation and growth pattern of titanium hydrides, and determine the fracture mode of Ti–6Al–4V. Depending on the hydrogen charging extent, the penetration of hydrogen and distribution of hydrides can be divided into three stages. In the initial stage hydrogen diffuses mainly into the β phase, as judged from its increase in Volta potential, and with no hydrides formed. Failure analysis after tensile tests exhibits plastic behavior and a fracture surface with mainly dimples. In the subsequent transition stage, hydrides are formed at the α/β interfaces and along α grain boundaries. More initial cracks occur in the brittle hydrides and the fracture surface transforms from dimple to quasi-cleavage. In the final stage a layer of uniformly distributed hydride is produced on the surface and within the α phase. Supported by nanoindentation measurements, the plasticity of the charged sample diminishes with hydrogen charging time, and an intergranular-transgranular mixed fracture is observed. Overall, the study forms clear evidence that the distribution and cracks of hydrides influence the fracture mode of the Ti-6A-4V alloy. • Hydrides form at α/β interface, grow along α grain boundaries, and occupy α grains. • Cracks initiate and propagate through soft-brittle hydrides. • The presence and distribution of hydrides determine the mode of fractures. • Hydrogen permeation increases the Volta potential difference between β and α phases. [ABSTRACT FROM AUTHOR]

The dependence on fossil fuels for energy has culminated in its gradual depletion and this has generated the need to seek alternative source that will be environmentally friendly and sustainable. Hydrogen stands to be promising in this regard as energy carrier which has been proven to be efficient. Magnesium hydride (MgH2) can be used in storing hydrogen because of its availability, light weight and low cost. In this review, monoatomic, alloy, intermetallic and composite forms of Ti, Ni, V, Mo, Fe, Cr, Co, Zr and Nb as additives on MgH2 are discussed. Through ball milling, additive reacts with MgH2 to form compounds including TiH2, Mg2Ni, Mg2NiH4, V2O, VH2, MoSe, Mg2FeH6, NbH and Nb2O5 which remain stable after certain de/hydrogenation cycles. Some monoatomic transition metals remain unreacted even after de/hydrogenation cycles. These formed compounds, including stable monoatomic transition metals, impart their catalytic effects by creating diffusion channels for hydrogen via weakening Mg - H bond strength. This reduces hydrogen de/sorption temperatures, activation energies and in turn, hastens hydrogen desorption kinetics of MgH2. Hydrogen storage output of MgH2/transition metal-based materials depend on additive type, ratio of MgH2/additive, ball milling time, ball -to combining materials ratio and de/hydrogenation cycle. There is a need for more investigations to be carried out on nanostructured binary and ternary transition metal-based materials as additives to enhance the hydrogen storage performance of MgH2. In addition, the already established compounds (listed above) formed after ball milling or dehydrogenation can be processed and directly doped into MgH2. [ABSTRACT FROM AUTHOR]

It is shown that a composite based on magnesium hydride and metal-organic framework, formed during mechanical synthesis in a high-energy ball mill, has a core–shell structure in which magnesium hydride particles are coated with nanoscale particles of the MIL-101 metal-organic framework. The distribution of particles of the metal-organic framework creates trapping centers and channels for hydrogen diffusion, resulting in a decrease in the temperature of hydrogen desorption from magnesium hydride by 270°C compared to pure MgH2. In turn, lowering the temperature leads to a decrease in the desorption activation energy, which can favorably influence the use of such a composite as a hydrogen storage material. An in situ analysis of the phase transitions during dehydrogenation has shown that the phase transitions in the composite occur in three main stages. The first stage is characterized by defect annealing and structure relaxation without hydrogen desorption, the second stage involves hydrogen desorption without hydride dissociation, and the third stage involves hydride dissociation followed by residual hydrogen desorption. [ABSTRACT FROM AUTHOR]

Decreasing hydride-induced embrittlement of zirconium-based cladding is a significant challenge for the successful dry storage of spent nuclear fuel. Herein, to radically minimize hydride-induced embrittlement, we used nanoparticles as sacrificial agents with a greater affinity than zirconium for hydrogen. Corrosion experiments in the presence of gold (Au) and palladium (Pd) nanoparticles under simulated pressurized water reactor (PWR) conditions revealed that the hydrogen content of the zirconium samples was remarkably reduced, with a maximum decrease efficiency of 53.9% using 65 nm Au and 53.8% using 50 nm Pd nanoparticles. This approach provides an effective strategy for preventing hydride-induced embrittlement of zirconium-based cladding. [ABSTRACT FROM AUTHOR]

Building upon our earlier results on the chemistry of nido‐1,2‐[(Cp*RuH)2B3H7] (Cp*=ɳ5‐C5Me5) (nido‐1) with different transition metal carbonyls, we continued to investigate the reactivity with group 7 metal carbonyls under photolytic condition. Photolysis of nido‐1 with [Mn2(CO)10] led to the isolation of a trimetallic [(Cp*Ru)2{Mn(CO)3}(μ‐H)(μ‐CO)3(μ3‐BH)] (2) cluster with a triply bridging borylene moiety. Cluster 2 is a rare example of a tetrahedral cluster having hydrido(hydroborylene) moiety. In an attempt to synthesize the Re analogue of 2, a similar reaction was carried out with [Re2(CO)10] that yielded the trimetallic [(Cp*Ru)2{Re(CO)3}(μ‐H)(μ‐CO)3(μ3‐BH)] (3) cluster having a triply bridging borylene unit. Along with 3, a trimetallic square pyramid cluster [(Cp*Ru)2{Re(CO)3}(μ‐H)2(μ‐CO)(μ3,ɳ2‐B2H5)] (4), and heterotrimetallic hydride clusters [{Cp*Ru(CO)2}‐{Re(CO)4}2(μ‐H)] (5) and [{Cp*Ru(CO)}{Re(CO)4}2(μ‐H)3] (6) were isolated. Cluster 4 is a unique example of a M2M′B2 cluster having diboron capped Ru2Re‐triangle. The hydride clusters 5 and 6 have triangular RuRe2 frameworks with one and three μ‐Hs respectively. All the clusters have been characterized by using mass spectrometry, 1H, 11B{1H}, 13C{1H} NMR and IR spectroscopies analyses and the structures of clusters 2–6 have been unambiguously established by XRD analyses. Furthermore, to understand the electronic, structural, and bonding features of the synthesized metal‐rich clusters, DFT calculations have been performed. [ABSTRACT FROM AUTHOR]

Accurate identifying and in‐depth understanding of the defect sites in a working nanomaterial could hinge on establishing specific defect‐activity relationships. Yet, atomically precise coinage‐metal nanoclusters (NCs) possessing surface vacancy defects are scarce primarily owing to challenges in the synthesis and isolation of such defective NCs. Herein we report a mixed‐ligand strategy to synthesizing an intrinsically chiral and metal‐deficient copper hydride‐rich NC [Cu57H20(PET)36(TPP)4]+ (Cu57H20). Its total structure (including hydrides) and electronic structure are well established by combined experimental and computational results. Crystal structure reveals Cu57H20 features a cube‐like Cu8 kernel embedded in a corner‐missing metal‐ligand shell of Cu49(PET)36(TPP)4. Single Cu vacancy defect site occurs at one corner of the shell, evocative of mono‐lacunary polyoxometalates. Theoretical calculations demonstrate that the above‐mentioned point vacancy causes one surface hydride exposed as an interfacial capping μ3‐H−, which is accessible in chemical reaction, as proved by deuterated experiment. Moreover, Cu57H20 shows catalytic activity in the hydrogenation of nitroarene. The success of this work opens the way for the research on well‐defined chiral metal‐deficient Cu and other metal NCs, including exploring their application in asymmetrical catalysis. [ABSTRACT FROM AUTHOR]