Theoretical Studies of the Electronic Structures and Spectrum Properties of Pt n Ni m (n + m = 7, n, m ≠ 0) Clusters

We studied Pt _n Ni _m (n + m = 7, n, m ≠ 0) clusters within the framework of the density functional theory (B3LYP) at the LANL2DZ level. The calculated results show that the Fermi levels are determined by the number of Pt atoms, which gain electrons from Ni atoms. Meanwhile, multifarious orbital hybridization is found in the frontier molecular orbital, and the more platinum or nickel atoms, the smaller energy gap it has. Moreover, the calculated IR and Raman spectrum indicates the aromatic character, which is vital for transitional metal clusters.     

Pt_nNi_m（n＋m=7,n,m≠0）团簇结构稳定性与磁学性质

采用密度泛函理论（DFT）中的杂化密度泛函B3LYP方法在LANL2DZ基组水平上对PtnNim团簇的各种可能构型进行了几何结构全优化,得出了它们的基态构型,并对其稳定性和磁学性质进行了计算研究.研究结果表明：PtnNim团簇的基态结构都为立体结构,对称性较低,多重度较高,Pt5Ni2团簇的稳定性最好;从磁性上看,Pt...     

SinP+m(n+m=5)结构和稳定性的理论研究

在实验的基础上 ,利用量子化学方法对 Sin P+ m( n+m=5 )的各种可能构型进行几何构型优化 ,预测各团簇的稳定结构 ,从中得出各个团簇稳定构型之间的基本关系 ,当 n>m时 ,团簇的稳定构型与 Si+ n 相似 ,而当 n相似文献   

Structurally nonrigid molecular complexes (HF)n(H2O)m (n + m ≥ 2) and their spectroscopic features

The problem of the formation and stability of structurally nonrigid, donor—acceptor molecular complexes is considered. These complexes are formed between the molecules of water and hydrogen fluoride, the latter being the hydrolysis product of the chemical, radiochemical, and metallurgical industrial wastes. Based on the results of ab initio quantum-chemical calculations of the potential energy surfaces by the Hartree—Fock—Roothaan method, the equilibrium configurations of the (H₂O) _n (HF) _m complexes (n : m = 1 : 1; 1 : 2; 2 : 1; 2 : 2; and 3 : 3) were determined. These configurations are necessary for correct interpretation of the IR absorption spectra and for routine remote monitoring of such environmentally hazardous complexes in the Earth atmosphere. The harmonic vibrational frequencies of the (H₂O) _n (HF) _m complexes (n + m 2) were calculated and the interaction energies between the monomers were found. The influence of UV radiation on the (H₂O) _n (HF) _n complexes (n = 1—3) upon the transition from the ground to the lowest excited singlet electronic state was studied. Characteristic spectroscopic features of the (H₂O) _n (HF) _m complexes were established.     

m × n] metal ion arrays templated by coordination cages

Three-dimensional m × n arrays of metal ion clusters can be assembled as aromatic stacks of planar polynuclear metal complexes within columnar coordination cages. The polynuclear complexes and cage height program the final array structures of the metal ion clusters. Cyclic trinuclear Au(I) complexes (m = 3) assembled into trigonal prismatic arrays (n = 1-3) within the cages and the array structures were clearly shown by X-ray crystallographic analysis. A silver-sandwiched hetero-Au(3)-Ag-Au(3) cluster was also prepared by treating a hexanuclear Au(3)-Au(3) cluster with Ag(I) ion.     

二元n+m(m≥3)相多体系可能实在网的拓扑结构

本文对作者提出的推导二元n+3相多体系全部可能实在网的方法和结果作进一步归纳,强调了这些网的构型与各稳定级别点的标记或作为标记的相,在化学成分图解上的位置之间确定的对应关系。在此基础上给出了构筑和检查二元n+m(m>3)相多体系可能网的一般原理:任何该类网应是一个或一个以上不同二元n+3相多体系网的合理拚接,其上分别缺失相同m—3相的点数均为n+3。因此,二元n+3相多体系网是二元n+m(m>3)相多体系网的基本构筑单元,作为例子,具体构筑了二元n+4相多体系具有最多稳定点的最大部分封闭网,确认这类网只有一张。     

TOPOLOGICAL CONFIGURATIONS OF POSSIBLE REAL NETS IN BINARY n+m(m≥3) PHASE MULTISYSTEMS

This paper further summarizes the method and results developed to find all possible real nets in binary n+3 phase multisystems, and emphasizes that there is a definite relationship between configurations and symbols of stable and metastable invariant points of nets or positions of phases as symbols on the chemographic bar. On the basis of these, a general principle is developed to construct and check possible neets in binary n+m (m>3) phase multisysterns: this sort of nets must be the reasonable combination of one or more than one distinct binary n+3 phase multisystem subnets, in which the number of points missing respectively same m—3 phases in n+3. Therefore, the binary n-4-3 phase nets are basic construction units of the binary n+m(m>3) phase nets. As an instance, the maximum partially closed net in binary n+4 phase multisystems, which has the most stable invariant points, is constructed, and it is indicated that this sort of net is unique.     

Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH2)m]n (n=1–4; m=3–7)

The Te ⋅⋅⋅ Te secondary bonding interactions (SBIs) in solid cyclic telluroethers were explored by preparing and structurally characterizing a series of [Te(CH₂)_m]_n (n=1–4; m=3–7) species. The SBIs in 1,7-Te₂(CH₂)₁₀, 1,8-Te₂(CH₂)₁₂, 1,5,9-Te₃(CH₂)₉, 1,8,15-Te₃(CH₂)₁₈, 1,7,13,19-Te₄(CH₂)₂₀, 1,8,15,22-Te₄(CH₂)₂₄ and 1,9,17,25-Te₄(CH₂)₂₈ lead to tubular packing of the molecules, as has been observed previously for related thio- and selenoether rings. The nature of the intermolecular interactions was explored by solid-state PBE0-D3/pob-TZVP calculations involving periodic boundary conditions. The molecular packing in 1,7,13,19-Te₄(CH₂)₂₀, 1,8,15,22-Te₄(CH₂)₂₄ and 1,9,17,25-Te₄(CH₂)₂₈ forms infinite shafts. The electron densities at bond critical points indicate a narrow range of Te ⋅⋅⋅ Te bond orders of 0.12–0.14. The formation of the shafts can be rationalized by frontier orbital overlap and charge transfer.     

[C(AuPH3)m]n+ (m=4-6; n=0-2)成键性质和稳定性研究

用MP2/LanL2DZ方法优化C(AuPH3)4[1a(C4v); 1b(Td)], [C(AuPH3)5]+[2a(C3h); 2b(Cs)]以及[C(AuPH3)6}]2+[3a(C2h); 3b(C2v)]的结构, 得到的几何参数与实验值相符. MP2水平下的自然键轨道(Natural bond orbitals, NBO)分析表明, Au具有d(sp)杂化性质, 其中(sp)具有s-p混合的轨道性质; 沿C-Au辐射方向形成的σ键和切向Au-Au之间的弱吸引相互作用使得整个分子稳定. 化合物1a, 2和3具有2或3个二电子三中心键, 表明该类化合物具有与传统C化学不同的电子结构和立体化学构型.     

Theoretical study of [Ni (H2O)n]2+(H2O)m (n ≤ 6, m ≤ 18)

The [Ni-(H(2)O)(n)](2+)(H(2)O)(m) (n ≤ 6, m ≤ 18) complexes were studied by means of first-principles all-electron calculations performed with the BPW91 gradient corrected functional and the 6-311+G(d,p) basis sets for the H, O, and Ni atoms. Triplet states were found as low-lying states for each (n, m) combination. The estimated Ni(2+)-(H(2)O)(n) binding energies (112.8-57.4 kcal/mol for the first layer and 52.0-23.0 kcal/mol for the second one) decreases and the Ni(2+)-OH(2) bond lengths lengthen as n + m increases. With six H(2)O moieties the Ni(2+) ion furnishes its first coordination sphere of octahedral geometry. Further water addition renders the formation of the second layer. The effect of Ni(2+) on the (H(2)O)(n)···(H(2)O)(m) hydrogen bond formation for several "n" and "m" combinations was studied, revealing an enhancement of this kind of bonding, which is of key importance for the stabilization and growth of the clusters. For some n + m isomers the second layer appears before the first octahedral layer is fully formed. For example, the square planar Ni(2+)-(H(2)O)(4) core originates two-dimensional 4 + 2 and 4 + 4 isomers, where each outer water molecule accepts two H-bonds, lying 2.0 kcal/mol above the 6 and 6 + 2 ground states. The clusters were also studied by IR spectra; the OH stretching vibrational frequencies allowed us to identify the outer solvation shells by the presence of red-shifted hydrogen bond regions.     

Existence of the homologous series of Y n Ba m Cu m + n O y (m = 2, 3, 5; n = 1, 2) oxides with the tetragonal and orthorhombic structures of YBa2Cu3O6 + δ

The phase composition of Y _x Ba_1?x CuO _y (x = 0.29?0.40) samples annealed in air (at 930?C990°C) and in an oxygen atmosphere (450?C800°C, P(O₂) = 101 kPa) was studied by X-ray powder diffraction, chemical analysis, electron diffraction, and elemental analysis in a transmission electron microscope. A considerable cation nonstoichiometry was discovered in particles having the tetragonal and orthorhombic structures of YBa₂Cu₃O_{6 + ??}. The variation range of particle compositions comprises matrix oxides of the Ba _m Cu _{m + n} O _y series with (Ba: Cu) 3: 5, 5: 8, 2: 3, and 5: 7, which in the presence of yttrium form the Y _n Ba _m Cu _{m + n} O _y series. Tetragonal oxides Y₂Ba₃Cu₅O _y (235), Y₃Ba₅Cu₈O _y (358), YBa₂Cu₃O _y (123), and Y₂Ba₅Cu₇O _y (257) are formed at the primary synthesis step in air and are preserved in an orthorhombic structure during short-term (1 h) oxygen annealing. Most particles of the 3: 5 and 5: 8 oxides are undersaturated with yttrium relative to the stoichiometry of the Y _n Ba _m Cu _{m + n} O _y series, those of the 2: 3 oxide correspond to this stoichiometry, and those of the 5: 7 oxide are supersaturated with yttrium over the stoichiometry. A trend is observed for the fractions of these oxides to change during long-term (5?C51 h) annealing in an oxygen atmosphere at 450°C and to the alternation of the dominant role of one of the four phases with the superconducting transition temperature T _c = 82, 85, 86, and 91 K. Each orthorhombic oxide undergoes structural transformations during oxygen annealing with a change in T _c. The coexistence of these oxides in the form of nanometer-sized domains does not allow their individual superstructures to be recognized.     

Theoretical Study of Electronic Structure and Stability of Mixed AlmBn−mH n 2− and CmBn−mH n 2−m (n = 6, 10, 12 and m = 1, 2) Clusters

Density functional theory (DFT) method with B3LYP functional and 6-311++G(d,p) basis set has been used to predict the geometries, relative stabilities, electronic structures and bonding analysis of Mixed Al_mB_n?mH _n ^2? and C_mB_n?mH _n ^2?m (n = 6, 10, 12 and m = 1, 2) clusters; being compared to the B_nH _n ^2? ones. Therefore, the DFT results suggest that the replacing of boron by aluminium or carbon is governed by Natural net charges following Gimar’s and Williams’s rules. The Al_mB_n?mH _n ^2? structures are relatively distorted compared to those of B_nH _n ^2? and C_mB_n?mH _n ^2?m . In Al_mB_n?mH _n ^2? structures Al atoms prefer the adjacent sites, however for the C₂B_n?2H_n cluster cages, the carbon atoms are positioned at diametrically opposed sites. The large HOMO–LUMO gaps show that the predicted clusters have chemical stabilities, principally, those of Al_mB_n?mH _n ^2? ones, which are not experimentally isolated. The optimized geometries obtained through boron substitution by Al and C lead to compactness and to contracted structures, respectively, where B–B bonds are the shortest in mono- and di-carbaboranes.     

Structural, electronic, bonding, magnetic, and optical properties of bimetallic [Ru(n)Au(m)](0/+) (n + m ≤ 3) clusters

The structural, electronic, bonding, magnetic, and optical properties of bimetallic [Ru(n)Au(m)](0/+) (n + m ≤ 3; n, m = 0-3) clusters were computed in the framework of the density functional theory (DFT) and time-dependent DFT (TD-DFT) using the full-range PBE0 non local hybrid GGA functional combined with the Def2-QZVPP basis sets. Several low-lying states have been investigated and the stability of the ground state spinomers was estimated with respect to all possible fragmentation schemes. Molecular orbital and population analysis schemes along with computed electronic parameters illustrated the details of the bonding mechanisms in the [Ru(n)Au(m)](0/+) clusters. The TD-DFT computed UV-visible absorption spectra of the bimetallic clusters have been fully analyzed and compared to those of pure gold and ruthenium clusters. Assignments of all principal electronic transitions are given and interpreted in terms of contribution from specific molecular orbital excitations.     

Crystal growth,structure determination and magnetism of a new m=3, n=1 member of the A3n+3mA′nB3m+nO9m+6n family of oxides: 12R-Ba12Rh9.25Ir1.75O33

Single crystals of a new Ba–Rh–Ir–O oxide were grown from a molten potassium carbonate flux. The new compound, Ba₁₂Rh_9.25Ir_1.75O₃₃, is structurally related to the 2H-hexagonal perovskite structure and contains pseudo one-dimensional chains of alternating units of ten face-sharing (Rh/Ir)O₆ octahedra and one (Rh/Ir)O₆ trigonal prism. The magnetic susceptibility of Ba₁₂Rh_9.25Ir_1.75O₃₃ is featureless, indicating the absence of magnetic order. The oxide is a semiconductor with a room temperature resistance of 280 Ω.     

AgmC60(OH)n(NO3)m的合成及其热稳定性

自从富勒烯被发现并克量级制备以来,富勒烯独特的结构和性质引起了人们极大兴趣和关注,对富勒烯及其衍生物的研究已迅速发展[1],由于C60具有光诱导剪切DNA、抑制艾滋病毒等特性,因而在生物化学及医学方面具有潜在应用前景,其中水溶性富勒烯衍生物的研究是富勒烯化学较为活跃的研究领域之一[2～5],尤其是羟基化富勒烯(或称富勒醇fullerenols)的合成方向的研究[5]。目前富勒烯羟基衍生物的合成方法已得以深入研究,但其化学反应性能的研究未见报道,本文合成了羟基C60银盐,并对其热稳定性能进行了研究。1　实验部分1 1　主要仪器及试剂C6…     

Sn_mO_n(m=1～3,n=1～2m)系列团簇的结构和电子性质

基于密度泛函理论(DFT)中的广义梯度近似(GGA)系统地研究了Snm On(m=1~3,n=1~2m)团簇的几何结构和电子性质.当m=n时,团簇的基态结构为Sn和O原子彼此相邻的环形结构,当nm时,团簇易于形成链状结构.研究发现:氧化锡团簇的物理和化学特性类似于氧化硅,主要表现为非金属性.对分裂途径、分裂能和能隙(HOMO-LUMO Gap)进行了研究,结果表明类氧化锡(Snm Om)、Sn2O3和Sn3O4团簇具有很好的稳定性,可以作为构建团簇聚合物材料的基本单元.而且,氧化锡团簇的稳定性主要与其组成成分和结构有关,与团簇大小无关.     

Formation of [M − nH + mNa](m−n)+ and [M − nH + mK](m−n)+ ions in electrospray mass spectrometry of peptides and proteins

The [M - nH + mNa](m-n)+ and [M - nH + mK](m-n)+ ions are common in the electrospray mass spectra of proteins and peptides. The feasibility of forming these ions in the gas phase via collision activation and/or ion-molecule reaction is investigated. Sodium and potassium affinities of the N-methylacetamide anion, the acetate anion, and the 1-propanamide anion have been calculated using density functional theory at the B3LYP/6-311+ +G(d,p) level of theory. These anions were chosen as models for the functional groups on a protein or peptide. These affinity values are then used to calculate reaction enthalpies of alkali hydroxides, chlorides, and hydrates with N-methylacetamide, acetic acid, the acetate anion, and 1-propanamine, model reactions that may lead to formation of the [M - nH + mNa](m-n) and [M - nH + mK](m-n)+ ions. It is found that a number of these reactions are exothermic or slightly endothermic (deltaH(o) < + 20 kcal/mol) and are accessible after collision activation in the lens region. The potential energy hypersurfaces of model reactions between NaOH and formamide as well as NaCl and formamide show relatively flat surfaces devoid of significant barriers.     

Joint photoelectron and theoretical study of (Rh(m)Co(n))⁻ (m=1-5, n=1-2) cluster anions and their neutral counterparts

Anion photoelectron spectroscopic experiments and calculations based on density functional theory have been used to investigate and uniquely identify the structural, electronic, and magnetic properties of both neutral and anionic (Rh(m)Co(n)) and (Rh(m)Co(n))(-) (m=1-5, n=1-2) clusters, respectively. Negative ion photoelectron spectra are presented for electron binding energies up to 3.493 eV. The calculated electron affinities and vertical detachment energies are in good agreement with the measured values. Computational results for geometric structures and magnetic moments of both cluster anions and their neutrals are presented.     

Photoelectron spectroscopy of (CO2)n(H2O) m − clusters

Photoelectron spectra of (CO₂)_nH₂O^? (2≤n≤8) and (CO₂)_n(H₂O) ₂ ^? (1≤n≤2) were measured at the photon energy of 3.49 eV. The spectra show unresolved broad features, which are approximated by Gaussians. The vertical detachment energies (VDEs) were determined as a function of the cluster size. For (CO₂)_nH₂O^?, the VDE-n plots exhibit a sharp discontinuity between n=3 and 4; the VDE value is ≈3.5 eV at n=3, while it drops down abruptly to 2.59 eV at n=4. This discontinuity in VDE is ascribed to "core switching" at n=4; a C₂O ₄ ^? dimer anion forms the core of (CO₂)_nH₂O^? for n≤3, while a monomer CO ₂ ^? is the core for n≥4. The (CO₂)₂(H₂O) ₂ ^? ion has a VDE of 2.33 eV, indicating the presence of a CO ₂ ^? monomer core in the binary clusters containing two H₂O molecules.     

Zur Kenntnis des m,m′-Divinylazobenzols und des m,m′-Divinylazoxybenzols

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