Structural, electronic, and magnetic properties of boron cluster anions doped with aluminum: BnAl- (2≤n≤9)

The geometrical structures, relative stabilities, electronic and magnetic properties of small B n Al (2 ≤ n ≤ 9) clusters are systematically investigated by using the first-principles density functional theory. The results show that the Al atom prefers to reside either on the outer-side or above the surface, but not in the centre of the clusters in all of the most stable B n Al (2 ≤ n ≤ 9) isomers and the one excess electron is strong enough to modify the geometries of some specific sizes of the neutral clusters. All the results of the analysis for the fragmentation energies, the second-order difference of energies, and the highest occupied-lowest unoccupied molecular orbital energy gaps show that B 4 Al and B 8 Al clusters each have a higher relative stability. Especially, the B 8 Al cluster has the most enhanced chemical stability. Furthermore, both the local magnetic moments and the total magnetic moments display a pronounced odd-even oscillation with the number of boron atoms, and the magnetic effects arise mainly from the boron atoms except for the B 7 Al and B 9 Al clusters.     

Hcp-icosahedron structural transformation induced by the change in Ag concentration during the freezing of （CoAg）561 clusters

The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimetallic clusters plays a key rolc in exploring new structural materials. In this paper, we study the influence of Ag concentration on the frozen structure of the （AgCo）561 cluster by using molecular dynamics simulation with a general embedded atom method. The results indicate that tt~e structure and chemical ordering of the （AgCo）561 cluster are strongly related to Ag concentration. Hcp-icosahedron structural transformation in the frozen （CoAg）561 cluster can be induced by changing Ag concentration. The chemical ordering also transforms to Janus-like Co Ag from core-shell Co-Ag.     

A theoretical study of the oxygen K-edge near-edge X-ray absorption ne structure of N2O/Ir(110)

A multiple-scattering cluster method is employed to calculate the oxygen K-edge near-edge X-ray absorption fine structure of N₂O/Ir(110) and its monolayer. Two peaks and one weak resonance appear in both cases. The selfconsistent field DV-X calculations of the peaks and resonance show that the physical origin of the pre-edge peak x is different from those of the main peak 1 and the other weak resonance σ₁. This setup is intrinsic to the N₂O monolayer, owing to the interaction between the neighbouring molecular chains in the monolayer and partly to the adsorbed atomic oxygen, according to both the theoretical and experimental data.     

Diffusion-Limited Aggregation with Polygon Particles

Diffusion-limited aggregation (DLA) assumes that particles perform pure random walk at a finite temperature and aggregate when they come close enough and stick together. Although it is well known that DLA in two dimensions results in a ramified fractal structure, how the particle shape influences the formed morphology is still unclear. In this work, we perform the off-lattice two-dimensional DLA simulations with different particle shapes of triangle, quadrangle, pentagon, hexagon, and octagon, respectively, and compare with the results for circular particles. Our results indicate that different particle shapes only change the local structure, but have no effects on the global structure of the formed fractal cluster. The local compactness decreases as the number of polygon edges increases.     

Synthesis,crystal structure,and thermal stability of ionic cluster compounds (phenH)4[Re4Q4(CN)12]·nH2O (Q = S,Se, n = 6; Q = Te,n = 10)

Three new salts of tetrahedral rhenium chalcocyanide cluster anions [Re₄Q₄(CN)₁₂]^4? (Q = S, Se, Te) and 1,10-phenanthroline-1-ium cations, (phenH)₄[Re₄S₄(CN)₁₂]·6H₂O (1), (phenH)₄[Re₄Se₄(CN)₁₂]·6H₂O (2), and (phenH)₄[Re₄Te₄(CN)₁₂]·10H₂O (3), have been synthesized by reactions of K₄[Re₄Q₄(CN)₁₂]·nH₂O with 1,10-phenanthroline in the presence of Nd³⁺ in an acidic aqueous medium (pH 4). 1 and 2 exhibit similar 2-D layered supramolecular architectures based on hydrogen bonds between water molecules, CN-groups of cluster anions, and phenH⁺ cations. The latter are involved in π–π and C–H?π stacking interactions, connecting the adjacent layers with each other. Complex 3 demonstrates a 3-D framework based on hydrogen bonds between water molecules and CN-groups, π–π and C–H?π interactions. Notably short O···Te contacts of 3.40 and 3.50 Å are found in the structure of 3. The thermal properties of 1–3 have been investigated by TG-DTG.     

Synthesis and crystal structure of a triple-decker CuII3TlI2 complex: first example of a thallium(I) system in the imino-phenolate Schiff base ligand family

This report deals with the synthesis, characterization, and crystal structure of a heteropentanuclear Cu^II₃Tl^I₂ compound [(Cu^IIL)₃Tl^I₂](NO₃)₂ (1), where H₂L=N,N′-ethylenebis(3-ethoxysalicylaldimine). This compound crystallizes in the monoclinic crystal system within space group C2/c. Each of the two symmetry related thallium(I) centers is located between a terminal and a common, central [Cu^IIL] by forming bonds with four phenoxo and three ethoxy oxygens. The three [Cu^IIL] moieties are parallel and hence 1 is a triple-decker system. Neighboring triple-decker moieties are interlinked by π?π stacking interaction and weak hydrogen bonds to generate 3-D self-assembly in 1. Salient features in the composition and structure of the title compound are discussed; the title compound is the first example of a thallium(I) system in imino-phenolate Schiff base family.     

Structures and luminescent properties of two heterotrimetallic Ln(III)–Sr(II)–K(I) complexes

Eu(III)–Sr(II)–K(I) and Tb(III)–Sr(II)–K(I) heterotrimetallic metal-organic frameworks with 2,4,6-pyridinetricarboxylic acid have been synthesized under hydrothermal conditions. The complexes are isomorphic and both in triclinic space group P-1. The ligands bond with three metal ions with two coordination modes. One connects seven metal ions and the other connects eight metal ions. IR spectra, thermal analysis, and photoluminescent properties have been studied. The results display strong characteristic emissions of Eu(III) or Tb(III) ions with excitation of ultraviolet radiation.     

Synthesis,characterization and crystal structure of a new linear trinuclear manganese(II) complex, [Mn3(PhCH=CHCO2)6(BPY)2] · H2O (BPY=2,2-bipyridine)

A new trinuclear manganese(II) complex, [Mn₃(PhCH=CHCO₂)₆(bpy)₂]?·?H₂O (1) (bpy?=?2,2-bipyridine), was synthesized by the reaction of Mn(OH)₂ with cinnamate in H₂O/methanolic solution and its solid state structure was determined by single crystal X-ray diffraction. Structural analyses suggest that 1 consists of a linear arrangement of three Mn(II) centers, bridged by six cinnamate carboxylate groups. Four of these carboxylates are syn–syn bidentate, and two are monodentate bridging plus bidentate chelating. Mn(2) on a crystallographic inversion center has a slightly disorted octahedral geometry; the terminal six-coordinate Mn(1) atoms are significantly distorted octahedra. Weak intermolecular interactions such as C–H?···?O hydrogen-bonding and π–π stacking are responsible for supramolecular assembly of the molecules. Compound 1 was characterized by infrared spectrum, thermogravimetric and X-ray powder diffraction analyses.     

3D Heterometallic 3d–4f coordination polymers based on organodisulfonate ligand with isonicotinic acid as a co-ligand: synthesis,crystal structures,photoluminescent and magnetic properties

The hydrothermal reaction of rare earth nitrates, CuCN, 2,7-naphthalenedisulfonate (2,7-nds), and isonicotinic acid (Hina) affords a new family of 3-D heterometallic 3d–4f coordination polymers, [Ln₂Cu(2,7-nds)₂(ina)₄(H₂O)₄]·4H₂O (Ln = Nd (1), Sm (2), Eu (3), Gd (4); 2,7-nds = 2,7-naphthalenedisulfonate, Hina = isonicotinic acid). Complexes 1–4 are structurally characterized by single crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy (IR), powder X-ray diffraction, and thermogravimetric analyses. X-ray crystal structure analyses reveal that 1–4 are isomorphous with dinuclear subunit [Sm₂(ina)₄] binding Cu ions to generate 2-D networks. Such 2-D networks are pillared by linking 2,7-nds ligands to result in the 3-D layer-pillared Ln(III)–Cu(II) coordination architectures. The valence of Cu salts changed in the reaction. In addition, the luminescence properties of 1–3 and the magnetic properties of 3 and 4 have also been investigated.