Ternary Cluster Research Articles

Atomically Precise Ternary Cluster: Polyoxometalate Cluster Sandwiched by Gold Clusters Protected by N-Heterocyclic Carbenes.

Coinage metal (Au, Ag, Cu) cluster and polyoxometalate (POM) cluster represent two types of subnanometer "artificial atoms" with significant potential in catalysis, sensing, and nanomedicine. While composite clusters combining Ag/Cu clusters with POM have achieved considerable success, the assembly of gold clusters with POM is still lagging. Herein, we first designedly synthesized two cluster structural units: an Au3O cluster stabilized by diverse N-heterocyclic carbene (NHC) ligands and an amine-terminated POM linker. The subsequent reaction involved amine substitution in the POM linker for the central O atom in the Au3O cluster, resulting in the first ternary composite cluster-a POM cluster sandwiched by two Au clusters protected by NHCs. Single-crystal X-ray diffraction and other characteristic methods characterized their atomically precise structures. Furthermore, altering the NHC ligands decreased the number of gold atoms in the sandwich structures, accompanying the different protonated degrees of amine ligand in the terminal end of the POM linker. These composite clusters showed excellent performances in catalytic H2O2 conversion through the synergistic effect between gold clusters and POM clusters. This work opens a new avenue to functional composite metal clusters and would promote their enhanced catalysis applications through intercluster synergistic interactions within composite systems.

Atomically Precise Ternary Cluster: Polyoxometalate Cluster Sandwiched by Gold Clusters Protected by N‐Heterocyclic Carbenes

AbstractCoinage metal (Au, Ag, Cu) cluster and polyoxometalate (POM) cluster represent two types of subnanometer “artificial atoms” with significant potential in catalysis, sensing, and nanomedicine. While composite clusters combining Ag/Cu clusters with POM have achieved considerable success, the assembly of gold clusters with POM is still lagging. Herein, we first designedly synthesized two cluster structural units: an Au3O cluster stabilized by diverse N‐heterocyclic carbene (NHC) ligands and an amine‐terminated POM linker. The subsequent reaction involved amine substitution in the POM linker for the central O atom in the Au3O cluster, resulting in the first ternary composite cluster—a POM cluster sandwiched by two Au clusters protected by NHCs. Single‐crystal X‐ray diffraction and other characteristic methods characterized their atomically precise structures. Furthermore, altering the NHC ligands decreased the number of gold atoms in the sandwich structures, accompanying the different protonated degrees of amine ligand in the terminal end of the POM linker. These composite clusters showed excellent performances in catalytic H2O2 conversion through the synergistic effect between gold clusters and POM clusters. This work opens a new avenue to functional composite metal clusters and would promote their enhanced catalysis applications through intercluster synergistic interactions within composite systems.

Komplexer Tanz von Molekülen am Himmel: Choreographie der intermolekularen Struktur und Dynamik im heteroternären Cluster Cyclopenten−CO2−H2O

AbstractDiese Studie untersucht die treibenden Kräfte hinter der Bildung eines heteroternären Clusters, der aus flüchtigen organischen Verbindungen industrieller Herkunft oder Verbrennungsquellen, insbesondere Cyclopenten, neben Treibhausgasen wie Kohlendioxid und Wasserdampf besteht. Obwohl beim Verständnis binärer Komplexe erhebliche Fortschritte erzielt wurden, sind die strukturellen Feinheiten heteroternärer Cluster weitgehend unerforscht. Unsere Studie charakterisiert den heteroternären Cyclopenten−CO2−H2O‐Cluster mithilfe der Fourier‐Transformations‐Mikrowellenspektroskopie. Im gepulsten Strahl wird ein Isomer beobachtet, in dem sich CO2 und H2O über dem Cyclopentenring ausrichten, wobei Wasser eine interne Rotation um seine C2‐Symmetrieachse vollführt. Theoretische Analysen stützen diese Beobachtungen und identifizieren eine O−H⋅⋅⋅π‐Wasserstoffbrücke und eine sekundäre C⋅⋅⋅O‐Tetrelbindung innerhalb des Clusters. Diese Studie stellt einen entscheidenden Schritt zum Verständnis der molekularen Dynamik und Wechselwirkungen von VOCs, Treibhausgasen und Wasser in der Atmosphäre dar und ebnet den Weg für weitere Untersuchungen ihrer Rollen in der Klimadynamik und Luftqualität.

Complex Dance of Molecules in the Sky: Choreography of Intermolecular Structure and Dynamics in the Cyclopentene-CO2-H2O Hetero Ternary Cluster.

This study delves into driving forces behind the formation of a hetero ternary cluster consisting of volatile organic compounds from industrial or combustion sources, specifically cyclopentene, alongside greenhouse gases like carbon dioxide, and water vapor. While substantial progress has been made in understanding binary complexes, the structural intricacies of hetero ternary clusters remain largely uncharted. Our research characterized the cyclopentene-CO2-H2O hetero ternary cluster utilizing Fourier transform microwave spectroscopy. The observed isomer in the pulsed jet has CO2 and H2O aligning above the cyclopentene ring, with water undergoing an internal rotation approximately about its C2 symmetry axis. Theoretical analyses support these observations, identifying an O-H⋅⋅⋅π hydrogen bond and a secondary C⋅⋅⋅O tetrel bond within this cluster. This study marks a critical step towards comprehending the molecular dynamics and interactions of VOCs, greenhouse gases, and water in the atmosphere, paving the way for further investigations into their roles in climate dynamics and air quality.

FK4H4-: Planar Tetracoordinate Fluorine Stabilized by Multicenter Ionic Bonding.

Planar tetracoordinate fluorine (ptF) species are very exotic and scarce due to high electronegativity of fluorine. Herein we report the ternary square ptF cluster, D4h FK4H4-, which is composed of a F center, a square K4 ring, and four outer H bridges. It is a true global minimum (GM) structure and possesses good dynamic stability. Bonding analyses indicate that there are four lone pairs for the central F atom, along with four K-H-K three-center two-electron (3c-2e) σ bonds for the peripheral K4H4 ligand ring. The stability of ptF is dominated by multicenter ionic bonds rather than the supposed σ aromaticity of the system. Excitingly, it is a pseudohalogen anion with the VDE 3.57 eV at the CCSD(T) level. The merge of ptF with pseudohalogen anion character makes the FK4H4- cluster an exotic species, which will motivate theoretical and experimental studies on novel ptF species as well as superhalogens.

Structural Expansion and Enhanced Photocurrent Conversion of Selenido Stannates with Cu+ Ions.

As a means of tuning the electronic properties of tin-chalcogenide-based compounds, we present a strategy for the compositional and structural expansion of selenido stannate frameworks under mild conditions by introducing Cu+ ions into binary anionic Sn/Se aggregates in ionothermal reactions. The variable coordination modes of Cu+-contrasting with tetrahedral {SnSe4} or trigonal bipyramidal {SnSe5} units-and corresponding expansion toward ternary Cu/Sn/Se substructures helped to add another degree of freedom to the nanoarchitectures. As desired, the variation of the structural features was accompanied by concomitant changes of the physical properties. Upon treatment of alkali metal salts of the [SnSe4]4- anion at slightly elevated temperatures (120 or 150 °C) in ionic liquids, we isolated a series of compounds comprising ternary or quaternary cluster molecules or networks of cluster units, (C2C2Im)9Li[Cu10Sn6Se22] (1), (C2C2Im)4[Cu8Sn6Se18] (2), (C2C1Im)3[Cu5Sn3Se10] (3), and (C2C2Im)5[Cu8Sn6Se18F]·(C2C2Im)[BF4] (4; C2C2Im = 1,3-diethyl-imidazolium, C2C1Im = 1-ethyl-3-methyl-imidazolium), which were investigated in terms of their optical gaps and photocurrent conversion properties. As illustrated by the synthesis and characterization of an additional salt that does not include Cu+, {(C2C2Im)2[Sn3Se7]}4·{(C2C2Im)[BF4]}2 (5), the significant role of Cu+ in this system was shown to be 3-fold: (a) structural expansion, (b) narrowing of the optical gap, and (c) photocurrent enhancement. By this three-in-one effect, the work offers an in-depth understanding of chalcogenido metalate chemistry with atomic precision.

Boron-based ternary MgTa2B6 cluster: a turning nanoclock with dynamic structural fluxionality.

Boron-based complex clusters are a fertile ground for the exploration of exotic chemical bonding and dynamic structural fluxionality. Here we report on the computational design of a ternary MgTa2B6 cluster via global structural searches and quantum chemical calculations. The cluster turns out to be a new member of the molecular rotor family, closely mimicking a turning clock at the subnanoscale. It is composed of a hexagonal B6 ring with a capping Ta atom at the top and bottom, whereas the Mg atom is linked to one Ta site as a radial Ta-Mg dimer. These components serve as the dial, axis, and hand of a nanoclock, respectively. Chemical bonding analyses reveal that the inverse sandwich Ta2B6 motif in the cluster features 6π/6σ double aromaticity, whose electron counting conforms to the (4n + 2) Hückel rule. The Ta-Mg dimer has a Lewis-type σ bond, and the Mg site has negligible bonding with B6 ring. The ternary cluster can be formulated as an [Mg]0[Ta2B6]0 complex. Molecular dynamics simulations suggest that the cluster is structurally fluxional analogous to a nanoclock, even at a low temperature of 100 K. The Ta-Mg hand turns almost freely around the Ta2 axis and along the B6 dial. The tiny intramolecular rotation barrier is less than 0.3 kcal mol-1, being dictated by the bonding nature of double 6π/6σ aromaticity. The present system offers a new type of molecular rotor in physical chemistry.

Coevolution of the interstellar chemistry: gas-phase laboratory formation of hydrogenated fullerene-PAH clusters

ABSTRACT Fullerene molecules are affected and constrained by different interstellar environmental factors, such as UV radiation, atoms, and other coexisting molecules. To understand the coevolution of the interstellar fullerene chemistry, by tracking the accretion processes on fullerene cations, we present an investigation of the chemical reactivity of fullerene (C60) cations and smaller fullerene (C54/56/58) cations with hydrogen and C14H10 in the gas phase. Experiments are performed using a quadrupole ion trap in combination with time-of-flight mass spectrometry. The experimental results show hydrogenated fullerene-C14H10 cluster cations (i.e. [Hn C60(C14H10)m ]+ and [Hn C54/56/58(C14H10)m ]+) are efficiently formed through ion-molecule collision reaction. H-atoms are more likely to accumulate on the surface of fullerenes than C14H10; not only does hydrogen more easily form a covalent bond, the later accreted hydrogen will also expel the already accreted C14H10. Through theoretical calculations, we obtain the structure of newly formed clusters (e.g. [HC60(C14H10)]+ and [HC58(C14H10)]+) and the binding energies of their reaction pathways, together with IR spectra. The bonding ability plays a decisive role in the ternary cluster formation processes, and the existence of occupation and expulsion competitive reaction channels in the accretion processes on fullerene surfaces is confirmed. As part of the coevolution of the interstellar chemistry, the occupation and expulsion reaction modes should be considered when fullerenes further react with H-atoms and PAHs. As a result, the molecular structures of hydrogen/fullerene/PAH clusters are diverse, and hydrogenated-fullerene-related clusters (e.g. hydrogenated fullerenes or hydrogenated fullerenes-PAHs) have a higher distribution than non-hydrogenated-fullerene-related clusters (e.g. fullerenes or fullerenes-PAHs) in the interstellar environment.

Synthesis and Characterization of Ternary Clusters Containing the [As16]10- Anion, [MM'As16]4- (M = Nb or Ta; M' = Cu or Ag).

The [Nb@As8]3- anion was first isolated from solution in 1986, and a number of isostructural [M@Pn8]n- clusters (M = Nb, Cr, or Mo; Pn = As or Sb; n = 2 or 3) have since been reported. We show here how anions of this class can be used as synthetic precursors that, in combination with sources of low-valent late transition metals (Cu and Ag), generate ternary polyarsenide cluster anions with unprecedented structural motifs. Chain type [MM'As16]4- (M = Nb or Ta; M' = Cu or Ag) units are found in compounds 2-5. These clusters contain a nortricyclane-like As7 cage and a [M@As8] crown, linked by a single As atom, and represent a fusion of two quite distinct branches of polyarsenide chemistry. Our analysis of the electronic structure confirms that the cluster retains many of the features of the component units. Electrospray ionization mass spectrometry reveals a series of smaller component ions containing 8-12 As atoms, the density functional theory-computed structures of which can be understood in terms of the pseudoelement concept. This work not only presents a new type of coordination mode for As clusters but also offers a point of entry for the rational design of multinary arsenic-based materials.

Ternary 14-electron XB2Be2 (X = Si, Ge, Sn, Pb) clusters: a planar tetracoordinate silicon (ptSi) system and its ptGe/Sn/Pb congeners.

A class of ternary 14-electron clusters, XB2Be2 (X = Si, Ge, Sn, Pb), have been computationally predicted with a planar tetracoordinate silicon (ptSi) unit, as well as its heavier ptGe/Sn/Pb congeners. These pentaatomic ptSi/Ge/Sn/Pb species are established as global-minimum structures via computer global searches, followed by electronic structure calculations at the PBE0-D3, B3LYP-D3, and single-point CCSD(T) levels. Molecular dynamics simulations indicate that they are also kinetically stable against isomerization or decomposition. Chemical bonding analyses show that the clusters have double 2π/2σ aromaticity. The latter concept underlies the stability of ptSi/Ge/Sn/Pb clusters, overriding the 14-electron count or its variants, such as the 18-electron rule. No sp3 hybridization occurs in these species, which naturally explains why they are ptSi/Ge/Sn/Pb (rather than traditional tetrahedral) systems.

Co2@(Ge17Ni)]4-: the first edge-sharing double-cage endohedral germanide.

We report here a new double-cage endohedral Ge cluster, [Co2@(Ge17Ni)]4-, fused through two [Co@(Ge9Ni)] moieties with a shared Ni-Ge edge. This ternary Co-Ge-Ni species not only represents the first double-cage example of an 18-vertex Zintl cluster, but also fills in the missing link of the edge fusion model in the double-cage systems.

Tetrahedral [Sb(AuMe)4 ]3- Occurring in Multimetallic Cluster Syntheses: About the Structure-Directing Role of Methyl Groups.

The anion of [K(crypt‐222)]3[Sb(AuMe)4]⋅py (1; crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane; py=pyridine) represents a rare example of a homoleptic heavy p‐block metal atom being surrounded by four free‐standing transition metal complex fragments, and the third example for a corresponding Sb compound. In contrast to all reported complexes of this type, the transition metal atoms possess twofold coordination only, hence the complex as a whole does not exhibit significant steric shielding or further linkage of the metal atoms. This is reflected in a high flexibility, as confirmed by slight deviations from a tetrahedral coordination of the Sb atom in the crystal and soft vibrational modes. An alternative pyramidal conformer, observed for a related arsenic compound with terminal phosphine ligands, is apparently disfavored owing to electron correlation effects. The compound is formed in a reaction that in another solvent or at other reactant concentrations yields salts of ternary cluster anions. By a combined experimental and theoretical study of different reaction conditions and previously unidentified side‐products, we provide insight into multimetallic cluster synthesis reactions.

Tetrahedral [Sb(AuMe)4]3−Occurring in Multimetallic Cluster Syntheses: About the Structure‐Directing Role of Methyl Groups

AbstractThe anion of [K(crypt‐222)]3[Sb(AuMe)4]⋅py (1; crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane; py=pyridine) represents a rare example of a homoleptic heavy p‐block metal atom being surrounded by four free‐standing transition metal complex fragments, and the third example for a corresponding Sb compound. In contrast to all reported complexes of this type, the transition metal atoms possess twofold coordination only, hence the complex as a whole does not exhibit significant steric shielding or further linkage of the metal atoms. This is reflected in a high flexibility, as confirmed by slight deviations from a tetrahedral coordination of the Sb atom in the crystal and soft vibrational modes. An alternative pyramidal conformer, observed for a related arsenic compound with terminal phosphine ligands, is apparently disfavored owing to electron correlation effects. The compound is formed in a reaction that in another solvent or at other reactant concentrations yields salts of ternary cluster anions. By a combined experimental and theoretical study of different reaction conditions and previously unidentified side‐products, we provide insight into multimetallic cluster synthesis reactions.

Quantitative analysis of the Portevin–Le Chatelier effect by combining digital image correlation and dead-weight-type tensile test

Abstract A quantitative evaluation method of a serration deformation behavior by a dead-weight tensile test combined with a strain measurement by a DIC method is proposed. This method applies to binary solid solution aluminum alloys and a ternary cluster strengthened aluminum alloy. In the dead-weight tensile test, the serrated flow was measured as a stress-strain curve with a stepped-shape divided into two stages of a stress rising phase and a strain burst phase. By adopting this tensile test, the serration deformation behavior can be measured with an extremely reproducibility. It was confirmed that an elastic deformation occurs predominantly in the stress rising phase, and this deformation behavior is discussed in relation to the concentration of solid solution elements. Propagation of PLC bands has occurred in the strain burst phase. An activation volume obtained from the strain rate in the PLC bands was in good agreement with a calculated value based on a distribution interval assuming a regular square distribution of solute elements. For the ternary alloy strengthened by clusters, it is also shown that this method can be applied to the qualitative estimation of the change in the residual amount of the solid solution element in the matrix during natural aging.

A new radioactive decay mode, true ternary fission, the decay of heavy nuclei into three comparable fragments

The ternary cluster decay of heavy nuclei has been observed in several experiments with binary coincidences between two fragments using detector telescopes (the FOBOS-detectors) with very large solid angles and placed on the opposite sides from the source of fissioning nuclei. The binary coincidences at a relative angle of $$180^{\circ }$$ correspond to binary fission or to the decay into three cluster fragments by registration of two of them in coincidences with missing nuclei of different masses (e.g. $$^{132}\hbox {Sn}$$ , $$^{52-48}\hbox {Ca}$$ , $$^{68-72}\hbox {Ni}$$ ). This marks a new step in the physics of fission-phenomena of heavy nuclei. The new decay mode has been observed more then 10 years ago by the FOBOS group in JINR (Dubna) Russia. These experimental results for the collinear cluster tri-partition, refer to the decay into three clusters of comparable masses. The observation of several other fission modes in the same system can be predicted by the potential energy surface, which show pronounced minima and valleys, they correspond to a variety of collinear ternary fission (multi-modal) decays. In the present work we discuss the various aspects of this ternary fission mode, with different mass partitions. The question of collinearity is analyzed on the basis of recent publications.

Molecular dynamics simulation of size, temperature, heating and cooling rates on structural formation of Ag-Cu-Ni ternary nanoparticles (Ag34-Cu33-Ni33)

We used molecular dynamics (MD) simulations with embedded atom method (EAM) potential to investigate the effect of size, simulation temperature heating and cooling rates on the nanoparticle formations, elemental distributions, melting, crystallization and phase transitions in equiatomic Ag-Cu-Ni ternary nanoparticle systems. Five model systems consisting of N = 412, 1348, 3173, 6222 and 10,843 total atoms of pure, metallic, single-oriented, spherical silver (Ag), copper (Cu) and nickel (Ni) particles used. A two-step heating process including relaxing and heating with fast, 1 × 1013 K s−1 and slow, 1 × 1011 K s−1 heating rates applied to monometallic Ag, Cu, Ni and ternary AgCuNi clusters to study melting behavior of systems. We obtained melting temperatures for various systems and found structural and morphological changes depend on the number of atoms in ternary cluster. A four-step thermal process including relaxing, heating, annealing and cooling applied to model systems to study effects of temperature (T = 1000, 1500 and 2000 K) and cooling rates (fast, 1 × 1013 K s−1 and slow, 1 × 1011 K s−1) for crystallization. We detected core–shell structure, Ag@CuNi for all simulations because of surface energy. The total energy of ternary clusters decrease linearly with increasing N, revealing similar mechanisms govern for core–shell structure and phase transitions. Energy-Temperature data of slow cooling rate have shown phase transition (crystallization) for monometallic Ag, Cu, Ni and ternary AgCuNi clusters, increasing with N. Fast cooling rate influences energy configuration and result in amorphous phases. Polyhedral template matching method applied to study phase transitions. For slow cooled clusters, face-centered cubic (FCC) and hexagonal close packed (HCP) structures are dominant while for fast cooled clusters, we observed amorphous phases with HCP and icosahedral structures. Furthermore, we used centrosymmetry parameter to identify the origin of the FCC structure. Our data show increasing simulation temperature and decreasing cooling rate favor crystallization of ternary AgCuNi clusters.

Dynamic fluxionality of ternary Mg2BeB8 cluster: a nanocompass.

A series of fluxional planar boron and boron-based binary clusters have evoked considerable interest of chemists. Here we propose the first ternary nanocompass cluster Mg2BeB8 based on quantum chemical calculations. It possesses a half-sandwich structure with a Mg2 dimer as the needle and a BeB8 molecular wheel as baseplate, which is the global minimum on the potential energy surface. Mg2BeB8 can be viewed as a nanocompass, whose Mg2 needle can rotate freely around the BeB8 baseplate at 300K. The calculated rotation barrier is only 0.1kcalmol-1 at the single-point CCSD(T)/6-311+G(d)//PBE0/6-311+G(d) level. Chemical bonding analyses indicate that Mg2BeB8 is a charge-transfer complex [Mg2]2+[BeB8]2- in nature. There is localized covalent Mg-Mg bond for [Mg2]2+ needle, while there are three delocalized π and three delocalized σ bonds for [BeB8]2- baseplate. The ionic bonding between the [Mg2]2+ needle and the 6π/6σ double aromatic [BeB8]2- baseplate makes the Mg2BeB8 cluster fluxional. The current results suggest that altering the baseplate is an effective way to enrich the nanocompass' family.

Boron-based ternary Rb6Be2B6 cluster featuring unique sandwich geometry and a naked hexagonal boron ring

Computational evidence is reported on a boron-based ternary Rb6Be2B6 cluster as the "Big Mac" sandwich on a subnanoscale with thickness of 0.58 nm. The core hexagonal B6 ring, occurring in the naked form due to double 6π/6σ aromaticity, is capped by two tetrahedral BeRb3 ligands. Such a B6 motif is scarce in boron clusters. The sandwich cluster has four-fold 2σ/6π/6σ/2σ aromaticity and its tetrahedral BeRb3 ligand is the simplest case of three-dimensional aromaticity (or spherical aromaticity). The sandwich can be formulated as a charge-transfer complex, [Rb3Be]3+[B6]6-[BeRb3]3+, whose components are held together by robust electrostatics, facilitating dual-mode dynamic fluxionality.

A Global Optimizer for Nanoclusters.

We have developed an algorithm to automatically build the global minimum and other low-energy minima of nanoclusters. This method is implemented in PyAR (https://github.com/anooplab/pyar) program. The global optimization in PyAR involves two parts, generation of several trial geometries and gradient-based local optimization of the trial geometries. While generating the trial geometries, a Tabu list is used for storing the information of the already used trial geometries to avoid using the similar trial geometries. In this recursive algorithm, an n-sized cluster is built from the geometries of n−1 clusters. The overall procedure automatically generates many unique minimum energy geometries of clusters with size from 2 up to n using this evolutionary growth strategy. We have used our strategy on some of the well-studied clusters such as Pd, Pt, Au, and Al homometallic clusters, Ru-Pt and Au-Pt binary clusters, and Ag-Au-Pt ternary cluster. We have analyzed some of the popular parameters to characterize the clusters, such as relative energy, singlet-triplet energy difference, binding energy, second-order energy difference, and mixing energy, and compared with the reported properties.

A giant enhancement of magnetic moment in a ternary three-shell icosahedral cluster: Fe@Mn12@Au20

ABSTRACTThe average magnetic moment per atom of Mn13 cluster is expected to be enhanced by doping or coating with a shell. Several ternary core–shell icosahedral clusters TM@Mn12@Au20 were constructed by combining substituting the central Mn with VIII elements (Fe, Co, Ni, Ru, Rh, Pd and Pt) and coating with a icosahedral Au20 shell, and systematically studied by using the first-principles density functional method. Compared to Mn13, Fe@Mn12@Au20 cluster shows a giant enhancement on total magnetic moment (52 µB) which can be greatly attributed to the ferromagnetic coupling between spin moments of atoms. Coating with Au20 shell enlarged the average distances of TM-Mn and Mn-Mn and is a useful way to change the magnetic coupling style. By analysis of density of states and electron localisation functional, we can conclude that the weak hybridisation between Fe and Mn in Fe@Mn12@Au20 is propitious to maintain their original direction of spin moments of atoms and then form ferromagnetic coupling.