Pentagonal Bipyramid Research Articles

Structures, simulated photoelectron spectroscopy, and electronic properties of CuASix(A = Sc, Cu, x ≤ 13) clusters: Relatively stable neutral pentagonal bipyramid structures of CuASi5

Structural design and optimization, simulated photoelectron spectroscopy, electronic properties and chemical bond analysis of CuASix(A = Sc, Cu, x ≤ 13) clusters were systematically studied using the PBE scheme to integrate with global search program of ABCluster. Firstly, neutral MS (the most stable structures) of CuASi5 of the basic 1 + 5 + 1 structures (1 metal + 5 silicons + 1 metal atoms) can be found as the basic units for assembling more lager clusters under the condition of neglecting distortions and minor changes. If the Cu atoms in Cu2Six(x ≤ 13) systems was replaced by one Sc atom, the geometries of MS will be reconstructed. Compared with the wheel geometries of Cu2Si12 and Cu2Si13, CuScSi12 and CuScSi13 clusters belong to near-wheel geometries with peripheral metal atoms. The neutral CuScSi5 and Cu2Si5 clusters possess relatively higher stability in all of cluster sizes. A combination of NPA analysis of CuASi5, sp of the Cu atom and spd of the Sc atom hybridizations were crucial to the chemical bonds of A–Si in the neutral CuASi5 clusters. In view of the higher SED value of the Cu2Si5 molecule, chemical bond analysis was carried out using MO, HLg and AdNDP analysis. 18 localized bonds and four delocalized bonds can play a positive role for the relative stabilities of neutral pentagonal bipyramid structures of Cu2Si5. Thus, the Cu2Si5 cluster with a lager HLg(1.80 eV) may be a good candidate for the basic unit of silicon-based semiconductor material assembly.

Hydroflux Synthesis and Structural Phase Transition of Rare-Earth Borate Hydroxides Na2[RE(BO3)(OH)2] (RE=Y, Gd-Er).

Reacting RE2O3 and H3BO3 in an ultra-alkaline NaOH hydroflux at about 250 °C yielded pure, crystalline samples of Na2[RE(BO3)(OH)2] (RE=Y, Gd-Er). The compounds dehydrate to Na3RE(BO3)2 upon heating in air to about 500 °C. Na2[RE(BO3)(OH)2] (RE=Tb-Er) are photoluminescent under UV radiation. Their UV-Vis spectra show the typical absorptions associated with 4f-4f transitions and absorption edges in the UV (band gaps ≥5.7 eV). The RE3+ cation is coordinated by seven oxygen atoms, which define a distorted pentagonal bipyramid. The bipyramids share trans-edges of their base forming infinite chains. Triangular (BO3)3- groups connect the chains into layers. The crystal structure of Na2[Ho(BO3)(OH)2] was investigated at various temperatures in the range 100 K≤T≤320 K. Above 310(2) K, the compound crystallizes in the orthorhombic space group Cmcm (β-phase), below, it undergoes a displacive phase transition of second order resulting in a monoclinic structure in space group C2/c (α-phase). The critical exponents derived from different structural parameters indicate a cooperative distortion of the borate layers, but a rather uncorrelated adaptation of the sodium cations to their local environment. The other compounds of the series also adopt the structure of the α-phase at 296 K.

Deep Learning Potential Assisted Prediction of Local Structure and Thermophysical Properties of the SrCl2-KCl-MgCl2 Melt.

The local structure and thermophysical properties of SrCl2-KCl-MgCl2 melt were revealed by deep potential molecular dynamicsdriven by machine learning to facilitate the development of molten salt electrolytic Mg-Sr alloys. The short- and intermediate-range order of the SrCl2-KCl-MgCl2 melts was explored through radial distribution functions and structure factors, respectively, and their component and temperature dependence were discussed comprehensively. In the MgCl2-rich system, the intermediate-range order is more pronounced, and its evolution with temperature exhibits a non-Debye-Waller behavior. Mg-Cl is dominated by 4,5 coordination and Sr-Cl by 6,7 coordination, and their coordination geometries exhibit distorted octahedra and distorted pentagonal bipyramids, respectively. A database of thermophysical properties of SrCl2-KCl-MgCl2 melts, including density, self-diffusion coefficient, viscosity, and ionic conductivity, was thus developed, covering the temperature range from 873 to 1173 K.

Study on structures, stabilities, electronic and magnetic properties of zirconium-doped magnesium clusters Zr2Mg n

Transition metal zirconium-doped magnesium clusters, Zr2Mg n (n = 1–11), were studied through a collaborative combination of the CALYPSO code and DFT calculations. The results show that the Zr2Mg n clusters have a structural transition from 2D to 3D at n = 2. The octahedral and pentagonal bipyramidal structures act as the basic units of subsequent structures to produce many derivative clusters from n = 6. In all Zr2Mg n clusters, Zr atoms tend to occupy high coordination positions and bind to most Mg atoms. Charge analysis reveals an electron transfer from Mg to Zr and significant spd hybridization behaviour in Zr2Mg n . Stability calculation suggests that the pentagonal bipyramid Zr2Mg5 cluster has a prominent stability, which benefits from its closed-shell electronic structure. The subsequent bonding analysis indicates that the bond order is Zr-Zr > Zr-Mg > Mg-Mg in the Zr2Mg5 cluster. For most sizes of Zr2Mg n , doping of Zr atoms induces a certain amount of magnetic moments, where the Zr2Mg, Zr2Mg7, and Zr2Mg8 clusters all have the largest magnetic moment of 4 μ B.

Ammonium Polyuranates: Old Dog, New Structural Tricks.

The crystal structure of ammonium polyuranates xUO3·yNH3·zH2O has been investigated. Powder X-ray diffraction (PXRD) has been employed to define single-phase samples within a series of synthesized compounds, which are further characterized by elemental analysis to ascertain the stoichiometry, revealing compositions of 3UO3·NH3·5H2O and 2UO3·NH3·3H2O. Analysis using extended X-ray absorption fine structure and vibrational spectroscopy has elucidated that both 3UO3·NH3·5H2O and 2UO3·NH3·3H2O possess a local structure similar to the metaschoepite─layered U(VI) oxohydroxide UO3·2H2O, but with H2O and NH4+ groups in the interlayers. The structures of ammonium polyuranates are solved from PXRD data, revealing their relationship to the U(VI) oxohydroxide with the established composition of NH4[(UO2)3O2(OH)3]·3H2O and NH4[(UO2)2O2(OH)]·2H2O for 3UO3·NH3·5H2O and 2UO3·NH3·H2O, respectively. These structures maintain the arrangement of U-O polyhedra as pentagonal bipyramids. However, disparities in lattice parameters, space group, and layer topology from UO3·2H2O emphasize significant structural modifications resulting from the substitution of water by ammonium. Moreover, the anion topology of the NH4[(UO2)2O2(OH)]·2H2O has no analogues among uranium oxohydroxide minerals. Notably, ammonium polyuranates, when compared, have minimal alterations in lattice parameters regardless of the presence of ammonia within the structure. The revealed results contribute valuable insights into the UO3-NH3-H2O system and hold potential applications in the field of nuclear power as ammonium polyuranates form during actinide precipitation in back-end of the nuclear fuel cycle and also serve as precursors in the fabrication of nuclear fuel.

Study the structure, stability and CO2 adsorption of the ScVB5 cluster

A combination of genetic algorithm and density functional theory (GA-DFT) was used to calculate the minimum structures of ScVB5 clusters. The thirteen isomers of ScVB5 cluster were investigated at the level of PBE/def2-TZVPP, TPSSh/def2-TZVPP, and TPSSh/def2-QZVP levels. The relative energies, the structural geometry, ionization energy, affinity energy of neutral isomers were reported. The ScVB5 cluster can be formed by adding atom into smaller clusters. The proposed structure of ScVB5 cluster for CO2 treatment is a pentagonal bipyramid in the Cs symmetry with vanadium atom at one of the vertices and scandium atom in the base of bipyramid. The favor position for adsorp CO2 by the ScVB5 cluster were at around of Sc and V atoms. The dual transition metal-doped boron clusters can interact with CO2 molecules stronger than pure boron clusters.

Structural properties and aromaticity of rare-earth doped tin cluster anion: MSn9− (M = Sc, Y, La)

Doping rare earth elements into clusters can significantly improve the performance and application value of the materials. The structure, bonding properties, stability, and aromaticity of MSn9− (M = Sc, Y, La) have been investigated using density-functional theory. The global minimum structure of these clusters is determined to be the addition of a triangle to the vertex position of a pentagonal bipyramid. Ab initio molecular dynamics simulations are used to demonstrate the thermal stability of the structure. Bonding analyses indicate the presence of ionic bonding and covalent bonding. Iso-chemical shielding surfaces and the gauge-including magnetically induced currents indicate that MSn9− clusters are significantly aromatic. This study provides a comprehensive understanding of tin-based nanomaterials, which is important for their design and synthesis.

Probing the structural and optical properties of Eu-doped LiAl5O8 using X-ray absorption and hard X-ray excited optical luminescence

X-ray absorption and hard X-ray excited optical luminescence were used to probe the structural and optical properties of LiAl5O8 doped with different Eu concentrations produced by the modified sol-gel method. X-ray diffraction studies revealed that all samples produced have a cubic spinel unit cell of LiAl5O8 and that some impurities of the EuAlO3 phase were observed at concentration limits of 4 and 5 %. Based on the XAS results, they show the stabilization of europium in both the trivalent and bivalent states and reveal that Eu3+ ion can stabilize both in distorted octahedral configurations (non-centrosymmetric) and in the form of pentagonal bipyramid sites. The XEOL spectra were excited at Eu LIII-edge is composed of typical emission peaks attributed to the emission of Eu3+ ions and contaminating ions (Cr3+ and Fe3+). An XEOL luminescence mechanism was also discussed based on the XEOL emission spectra.

Nicotinamide, acetate and their two new complexes with Zn(II) and Cd(II)

Two new complexes of Zn(II) and Cd(II) with acetate and nicotinamide as mixed ligands were synthesized and characterized. The Zn(II) complex is mononuclear, [Zn(ac)2(NA)2] (1), while the Cd(II) is a dinuclear one, [Cd2(ac)4(NA)4].2H2O (2), where ac = acetate and NA = nicotinamide. The compounds were characterized by means of single-crystal X-ray diffraction, FTIR, 1H NMR, 13C NMR spectroscopy, thermal analysis and elemental analysis. The geometry of the metal ion is distorted tetrahedral for Zn(II) and distorted pentagonal bipyramid geometry for Cd(II). In the dinuclear complex, each metal ion is coordinated by three acetate groups, but there are two different types of coordination modes for the acetate ligands: bidentate chelating and bridging bidentate chelating.

Coordination compounds of indium, gadolinium, and erbium nitrates with low urea content

Objectives. To date, compounds of rare earth nitrates with urea in a ratio of 1:4 and indium in a ratio of 1:6 have been synthesized and structurally characterized. However, there is a lack of research into similar compounds having a lower urea content. The purpose of this work was to continue the search for regularities of structure formation for complexes of various elements with urea.Methods. Novel coordination compounds were synthesized and characterized by powder- and single-crystal X-ray diffraction analysis, as well as infrared spectroscopy.Results. The interaction of indium, gadolinium and erbium nitrates with urea (Ur) in an aqueous solution under conditions of ligand deficiency produces the previously unknown coordination compounds cis-[In(Ur)4(NO3)2]NO3, [Gd(H2O)2(Ur)2(NO3)3], and [Er(H2O)2(Ur)(NO3)3]. The indium complex is shown to have an ionic structure, whereas the gadolinium and erbium complexes have a molecular structure. In the indium complex, the coordination number is 6; the cation has an octahedral structure; it involves two cis-arranged monodentate nitrate groups and four monodentate urea molecules. The coordination number of gadolinium is 10; here, the coordination polyhedron is a distorted pentagonal bipyramid at the vertices of which there are two water molecules, while in the internal polygonal base there are two monodentate urea molecules and three bidentate chelating nitrate groups oriented perpendicular to the polygonal base of the bipyramid. The coordination number of erbium is 9; the coordination polyhedron is a distorted tricapped trigonal prism.Conclusions. In contrast with the gadolinium complex, one urea molecule is coordinated in the erbium complex instead of two, decreasing the coordination number from 10 to 9. In the indium complex cation, the coordination number is 6; unlike the gadolinium and erbium complexes, the cation does not contain water, and the nitrate groups are monodentate.

Self-assembly of a unique triangle-like tungstovanadate containing pentagonal {(WO7)W3(SnR)2} cluster.

In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K10H10.5[(W4O15(H2O)2){(SnCH2CH2COO)2(V0.75W10.75/V0.25O39)}{{(SnCH2CH2COO)2(μ-OH)}2(SnCH2CH2COO)(VW10O37)}2]·31H2O ((SnR)8-V3W35, R = CH2CH2COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW11O39]7- ({VW11}) and two [VW10O37]9- ({VW10}) units connected by eight [Sn(CH2)2COO]2+ groups and a {W4O19} cluster. Interestingly, there exists a pentagonal bipyramid WO7 polyhedral center surrounded by two SnCO5 and three WO6 octahedra, forming a pentagonal {(WO7)W3(SnR)2} cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic-inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119Sn and 51V NMR, IR, thermal gravimetric analysis (TGA), etc. In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o-phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H2O2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives.

Alternative technologies of composite of highly loaded aircraft structures: a qualitative method for making multicriteria decisions: Part III. Research of the methodological basis in decision-making: technological constructions in in the assessment toolki

The third part of the article proceeds from the starting points in the decision-making problem (DMP) specified in the first stages of research [1, 2]. Here, we continue to compare the predominance (first of all, quality) of autoclave and non-autoclave alternative technological processes (ATP) as part of the stages of TP(e) with a linear algorithm of end-to-end action in the manufacture of carbon fiber (CF) aircraft structures (AC) such as highly loaded wing stringer panels (HLS) of B787, A350, MC-21, CSeries mainline aircraft as a component of hierarchical systems. To describe and study them, the following were involved: initial technological and verbal models, technological and mathematical model of an autonomous dynamic system (ADS) and a number of two-dimensional manifolds (topology) to it in the form of technological and geometric models. The article continues the study of development in this direction by approximating manifolds by polyhedra. Including co-cellular and double-formed structures - pentagonal pyramids and bipyramids, as well as bodies of revolution around them - cone and bicon. Examples of schematic and technological interpretive modeling are presented. The methodological basis is the main provisions of decision-making theory, factor analysis and system-process approach with the involvement of practice results (expert analysis), first of all, the definition of technological factors of processes with criterion assessments of the advantages, components of alternatives in their competitive strategies.

Local Structure and Speciation-Driven UO22+ → Sm3+ Energy Transfer for Enhanced Luminescence in Li2B4O7.

Herein, we report the uranyl sensitization of Sm3+ emissions in uranium-codoped Li2B4O7:Sm3+ phosphor. The uranyl speciation in codoped [Sm, U] LTB samples was determined by synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy that revealed two coordination shells for U(VI) ions with bond distances of U-Oax (∼1.81 Å) and U-Oeq (∼2.30 Å). EXAFS fitting suggested that the uranyl moiety is present as pentagonal bipyramids (UO7) and hexagonal bipyramids (UO8) with five and six equatorial oxygen ligands, respectively. The alteration of the local structure of Sm3+ from [SmO4] to [SmO7] polyhedra and the changes in the coordination number of equatorial oxygen for uranyl were observed with different codoping concentrations of Sm3+ and uranium. Density functional theory (DFT) calculations suggested the lowering of defect formation energy for Li vacancies on codoping of Sm and U. Hence, we proposed the increase of the equatorial coordination number of UO22+ on the increase in the lithium vacancies in LTB. In addition, DFT supported the feasibility of efficient energy transfer (ET) due to the overlap of uranium and Sm3+ excited state levels. The influence of the same on the spectral features and UO22+ → Sm3+ energy transfer was investigated by time-resolved photoluminescence (PL) studies. The ET efficiency from the UO22+ to Sm3+ was 70.5% in 0.5 mol % codoped [Sm, U] LTB samples. The correlation of EXAFS and luminescence properties indicated a red shift in vibronic features of uranyl emission with increase in the equatorial coordination of the uranyl moiety from five to six. Additionally, a higher probability of ET was observed for uranyl speciation as UO8 hexagonal bipyramids. Temperature-dependent emissions and decay profiles were collected under uranyl excitation to investigate the thermal dependence of ET. A high energy barrier (Ea ∼ 4027 cm-1) was evaluated for the thermal quenching of Sm3+ emissions. This work provides insights into the modulation of luminescence and ET efficiency via structural changes in uranyl and Sm local environment in LTB phosphor.

Theoretical study on structural evolution, photoelectron and vibrational spectra, and thermochemistry properties of neutral, anionic and di-anionic titanium-doped tin (TiSnn0/−/2− (n = 4–17)) nanoalloy clusters

The structural evolution, chemical stability, electronic and vibrational properties, as well as charge transfer and bonding character of TiSnn0/−/2− (n = 4–17) clusters have been performed with density functional theory calculations using ABCluster search technique. Structurally, it is found that the growth patterns prefer three kinds of absorbed stages from polygonal bipyramidal configuration for n = 4–6, to absorbing additional Sn on the adjacent surfaces of pentagonal bipyramid unit from n = 7–12, and finally to the TiSn130/−/2− cluster as the first foundational architectures, of which the encapsulated cage structure is formed when n = 11. The simulated PES spectra agree with available experiments. More interestingly, the neutral TiSn16 cluster not only possesses the high thermodynamic and relative stability but also preferable photochemical reactivity, that can be further explained by superatom features and delocalized multi-center bonds (AdNDP), while the strong p-d hybridization between Ti atom and Sn unit plays an important role in the stabilities of clusters, making it as the most suitable building units. In addition, the UV–Vis absorption spectra of TiSn16 are discussed, and the main transitions of crucial excited states are analyzed in detail. The Infrared and Raman vibrational characteristic peaks of all these neutral and charged species are properly assigned, of which the TiSnn0/−/2− (n = 10–17) clusters possess degenerating deformation mode of Ti atom wagging in Sn cage framework (Infrared active) and breathing mode of Sn cage framework (Raman active). All these findings will provide a further understanding for the nanoalloy cluster as the most suitable building block with further development as a potential optoelectronic material.

Anion Photoelectron Spectroscopy and Theoretical Studies of Ge3n+1O (n = 1-3) Clusters with the C3v Symmetric Ge3 Structural Unit.

We investigate Ge3n+1O-/0 (n = 1-3) clusters using anion photoelectron spectroscopy and theoretical calculations. The results show that the lowest energy structure of Ge4O- is a bent Cs symmetric trigonal bipyramidal structure, while Ge4O has a C3v symmetric trigonal bipyramidal structure. Ge7O- has two coexisting low-lying isomers, the first one can be viewed as a Ge2O unit interacting with a Ge5 trigonal bipyramid, the second one can be regarded as an O atom interacting with a Ge7 pentagonal bipyramid; whereas Ge7O has a C3v symmetric structure with a Ge atom and an O atom capping a Ge6 trigonal antiprism from the bottom and top, respectively. The structures of Ge10O- and Ge10O can be obtained by adding an O atom to different binding sites of a C3v symmetric Ge10. Chemical bonding analyses of Ge3n+1O (n = 1-3) reveal that the O atom interacts with its neighboring three Ge atoms forming one 4c-2e σ bond and two 4c-2e π bonds in the top Ge3O trigonal pyramid, while the terminal Ge atom forms one 4c-2e σ bond in the bottom Ge4 trigonal pyramid. The large HOMO-LUMO gaps of Ge3n+1O (n = 1-3) indicate that they have good stabilities. Ab initio molecular dynamics simulations suggest that both Ge7O and Ge10O are dynamically stable in general at 300 and 500 K. The current work suggests that the C3v symmetric Ge3 units and the insertion growth pattern may be viable for constructing 1D germanium oxide nanostructures with the chemical formula of Ge3n+1O.

Probing the effect of Y3+/Gd3+ on the optical properties of Gd2-xYxTiO5:Eu3+: Insight into local site-luminescence correlation

Phosphor converted light emitting diodes (pcLEDs) are considered as the most efficient materials to resolve the issue of energy scarcity. In this regard, the design of an efficient red phosphor could be a game changer due to the lack of the same in the current existing phosphor library. Here in this work, we have investigated high color purity, moderate photoluminescence quantum yield (PLQY) and long excited state lifetime red emitting Gd2-xYxTiO5:1.0 %Eu3+ phosphor with varying Y3+/Gd3+ ratio. It was found that higher Y3+ containingGd0.5Y1.50TiO5:1% Eu3+ emerged victorious in terms of luminescence intensity, asymmetry ratio and PLQY ∼ 10 %. Higher PLQY of this particular composition has been attributed to lowest non-radiative channels in them. The same has been further supported by PALS as it suggested lowest defect density in Gd0.5Y1.50TiO5:1% Eu3+ as most of the vacancies have moved out of the lattice to the surface and is responsible for improved optical properties as defect triggered non-radiative pathways reduced significantly. The O2–→ Eu3+ charge transfer energy on the other hand eases in higher gadolinium counterparts owing to more structural distortion of distorted pentagonal bipyramid (DPB) and distorted hexagonal bipyramid (DHB) in them. Based on the number of Stark components of 5D0→7F0 there are two types of Eu3+ with distinct chemical environments. It was inferred that longer lived trivalent europium ions are the one located at a less distorted DPB whereas short lived Eu3+is ascribed to the one occupying a highly distorted DHB. The trend in Judd-Ofelt parameter Ω4 < Ω2 revealed that Eu3+ ions are localized in high asymmetric locations in all the samples under the doping level used in this work. The high branching ratio of 5D0→7F2 transitions for all the samples reflected in very high color purity of more than 99 %. These results suggest that Eu3+doped A2TiO5 luminescent crystals with moderate PLQY, high red color purity and long excited state lifetime could serve as efficient red phosphor and with further improvement can be potential candidate for various applications.

Uranyl silicate nanotubules in Rb2[(UO2)2O(Si3O8)]: synthesis and crystal structure

Abstract A new rubidium uranyl silicate, Rb2(UO2)2O(Si3O8) (1), was obtained using high-temperature approach from the melt in silica tubes. Its crystal structure was solved by direct methods: hexagonal, P6/m, a = 27.7992(7), c = 7.2346(2) Å, V = 4841.8(3) Å3, R 1 = 0.033. The structure of 1 represents a new structure type with unprecedented topology not observed before among U(VI) oxides and oxysalts. It is comprised of layers with large voids derived from the U3O8 structure formed exclusively by pentagonal UrO5 bipyramids. The low-occupied Rb sites are located in the interlayer space. The SiO4 silicate tetrahedra in the structure of 1 share vertices to form rolled [Si6O16]8− chains. The nanotubules [(UO2)(Si6O16)]6− penetrate through both U3O8-derived layers and Rb interlayer. These tubules are attached to the U3O8 derived sheets via uranyl-uranyl interactions and edge-sharing between silicate tetrahedra and UrO5 bipyramids.

Pentagonal bipyramid-shaped REGe6− (RE = Sc, Y, La, Ce, Pr, Nd, Pm, Sm, and Eu) clusters with adjustable magnetic moments

The geometries, electronic, and magnetic properties in a series of rare-earth (RE) metal atoms (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, and Eu) doped Ge clusters, REGe6−, are investigated using density functional theory calculations and the results are compared with experimental literature data. It was found that all REGe6− clusters have similar pentagonal bipyramid structures, where the RE atom is located at the top (or side) of the pentagonal bipyramid. Natural population analysis reveals that the electrons always transfer from the RE atom to parent germanium atoms. The spin density and the density of states diagrams visually showed that the magnetic moments increase monotonically from Sc to Eu, which mainly derive from the contribution of the RE atoms. Isochemical shielding surfaces analyses indicate that the most regions of the REGe6− clusters (i.e., the pentagonal and the tetragonal ring in REGe6−) exhibit strong aromaticity compared with the benzene ring.

Mixed-Valence NpV/AnVI Molybdate Complexes with Single-Charge Outer-Sphere Cations.

Five new mixed-valence NpV/AnVI molybdates of the composition [C(NH2)3]3[(NpVO2)(NpVIO2)(MoO4)3(H2O)]·H2O (1), [C(NH2)3]3[(NpVO2)(NpVIO2)(MoO4)3(H2O)]·3H2O (2), Na3[(NpVO2)(PuVIO2)(MoO4)3(H2O)]·nH2O (3), Na6[(NpVO2)2(UVIO2)(MoO4)5]·13H2O (4), and LiNa2[(NpVO2)(NpVIO2)2(MoO4)4(H2O)]·4H2O (5) have been synthesized and structurally characterized. The coordination polyhedra of the NpV and AnVI atoms in compounds 1-5 are pentagonal bipyramids. The basis of structures 1-3 is anionic layers of the composition [(NpVO2)(AnVIO2)(MoO4)3(H2O)]n3n-. Three crystallographically independent molybdate ions are tridentate-bridging ligands. The water molecule, which is a part of the anion layer, is coordinated to the NpV atom. The anionic layers in complexes 2 and 3 have the same structure, different from 1. The basis of structure 4 is anionic layers of the composition [(NpVO2)2(UVIO2)(MoO4)5]n6n-, the structure of which differs from the structure of anionic layers in 1-3. Complex 5 has a three-dimensional (3D) structure. The spectra of all compounds in the UV-visible and IR ranges were measured and analyzed.

Making Sense of the Growth Behavior of Ultra-High Magnetic Gd2-Doped Silicon Clusters

The growth behavior, stability, electronic and magnetic properties of the Gd2Sin− (n = 3–12) clusters are reported, which are investigated using density functional theory calculations combined with the Saunders ‘Kick’ and the Artificial Bee Colony algorithm. The lowest-lying structures of Gd2Sin− (n = 3–12) are all exohedral structures with two Gd atoms face-capping the Sin frameworks. Results show that the pentagonal bipyramid (PB) shape is the basic framework for the nascent growth process of the present clusters, and forming the PB structure begins with n = 5. The Gd2Si5− is the potential magic cluster due to significantly higher average binding energies and second order difference energies, which can also be further verified by localized orbital locator and adaptive natural density partitioning methods. Moreover, the localized f-electron can be observed by natural atomic orbital analysis, implying that these electrons are not affected by the pure silicon atoms and scarcely participate in bonding. Hence, the implantation of these elements into a silicon substrate could present a potential alternative strategy for designing and synthesizing rare earth magnetic silicon-based materials.