Blue-shifted hydrogen-bonded complexes. II. CH3F(HF)1 n 3 and CH2F2(HF)1 n 3

The equilibrium structures, binding energies, and vibrational spectra of the clusters CH₃F(HF)_{1 n 3} and CH₂F₂(HF)_{1 n 3} have been investigated with the aid of large-scale ab initio calculations performed at the Møller–Plesset second-order level. In all complexes, a strong C–FH–F halogen–hydrogen bond is formed. For the cases n = 2 and n = 3, blue-shifting C–HF–H hydrogen bonds are formed additionally. Blue shifts are, however, encountered for all C–H stretching vibrations of the fluoromethanes in all complexes, whether they take part in a hydrogen bond or not, in particular also for n = 1. For the case n = 3, blue shifts of the ν(C–H) stretching vibrational modes larger than 50 cm⁻¹ are predicted. As with the previously treated case of CHF₃(HF)_{1 n 3} complexes (A. Karpfen, E. S. Kryachko, J. Phys. Chem. A 107 (2003) 9724), the typical blue-shifting properties are to a large degree determined by the presence of a strong C–FH–F halogen–hydrogen bond. Therefore, the term blue-shifted appears more appropriate for this class of complexes. Stretching the C–F bond of a fluoromethane by forming a halogen–hydrogen bond causes a shortening of all C–H bonds. The shortening of the C–H bonds is proportional to the stretching of the C–F bond.     

UO22＋•nH2O和PuO22＋•nH2O (n＝2, 4, 5, 6)密度泛函理论研究

首先用密度泛函理论(DFT)方法研究了铀酰和钚酰离子的几何与电子结构, 计算结果与实验基本符合, 表明DFT方法也能用于含铀和钚重原子的化合物计算. 然后对铀酰和钚酰水合离子的几何构型、Mulliken集居数分布以及铀酰(钚酰)与配体水分子的结合能进行计算, 计算结果表明UO₂^2＋•5H₂O和PuO₂^2＋•5H₂O分别为铀酰和钚酰系列水合离子中最稳定的配合物.     

Simultaneous Aromatic–Beryllium Bonds and Aromatic–Anion Interactions: Naphthalene and Pyrene as Models of Fullerenes,Carbon Single‐Walled Nanotubes,and Graphene

The possibility of forming stable BeR₂:ArH:Y^? (R=H, F, Cl; ArH=naphthalene, pyrene; Y=Cl, Br) ternary complexes in which the beryllium compounds and anions are located on the opposite sides of an extended aromatic system is explored by means of MP2/aug‐cc‐pVDZ ab initio calculations. Comparison of the electron‐density distribution of these ternary complexes with the corresponding BeR₂:ArH and ArH:Y^? binary complexes reveals the existence of significant cooperativity between the two noncovalent interactions in the triads. The energetic effects of this cooperativity are quantified by evaluation of the three‐body interaction energy Δ³E in the framework of the many‐body interaction‐energy (MBIE) approach. Although an essential component of the interaction energies is electrostatic and is well reflected in the changes in the molecular electrostatic potential of the aromatic system on complexation, strong polarization effects, in particular for the BeR₂:ArH interactions, also play a significant role. The charge transfers associated with these polarization effects are responsible for significant distortion of both the BeR₂ and the aromatic moieties. The former are systematically bent in all the complexes, and the latter are curved to a degree that depends on the nature of the R substituents of the BeR₂ subunit.     

Properties of meso-tetrakis (4- n -alkanoyloxyphenyl) porphyrin liquid crystal Co and Ni complexes

Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid crystal properties and display a hexagonal columnar discotic columnar (Col_h) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, ¹H NIVR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence, and surface photovoltage spectroscopy. Supported by the National Natural Science Foundation of China (Grant No. 59783001), the Natural Science Foundation of Shandong Province (Grant No. Y2006B41), the Foundation of Shandong Provincial Education Department (Grant No. J06A53), the Natural Science Foundation of Shandong University of Technology (Grant No. 2004KJM15) and Doctor Foundation of Shandong University of Technology     

On the analog of benzene B6H 6 n ? , 2 ≤ n ≤ 6: Geometry of B6H 6 n ? anions

The possibility of existence of the B₆H ₆ ⁶⁻ anion as the analog of the benzene molecule with a planar structure was considered. It was shown that on addition of two electrons to the [B₆H ₆ ⁴⁻ (O _h )] anion, the change from the octahedral to the planar geometry and the formation of B₆H ₆ ⁶⁻ (C _6v ) is thermodynamically unfavorable. The lithium ions in Li₆B₆H₆ can be used as the stabilizing coordination factor in the anion. The occurrence in the B₆H ₆ ⁿ⁻ ions (n = 2−6) of the shared π-electrons responsible for the formation of the highly aromatic systems with the planar geometry was shown to be impracticable. Original Russian Text ? N.T. Kuznetsov, S.P. Ionov, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 10, pp. 738–741.     

VB2n-(n=8~12)团簇几何结构、电子及热力学特性的理论研究

基于卡里普索结构预测程序和密度泛函理论的第一性原理计算,搜索确定了VB_2n^-（n=8~12）团簇的基态和亚稳态结构。结果发现,V原子的掺杂完全改变了原硼团簇的结构并提高了原体系的稳定性。掺杂体系基态结构分别呈现高对称性的鼓状（VB₁₆^-：C_2v）、管状（VB₁₈^-：C_2v和VB₂₀^-：C_s）及笼状（VB₂₂^-：C₂和VB₂₄^-：D_3h）结构。基于基态结构,研究了体系的电荷转移和极化率,拟合出了光电子能谱、红外和拉曼谱图,分析了流变键和芳香特性。最后,研究了体系的热力学特性,讨论了温度对热力学参数的影响。     

Formation and Characterization of Large (Ar) n , (N2) n , and Mixed (Ar) n (N2) m van der Waals Clusters Produced by Supersonic Expansion

This paper reports the formation and characterization of large (Ar) _n , (N₂) _n , and mixed binary (Ar) _n (N₂) _m van der Waals clusters produced at room temperature in the process of supersonic expansion. The average cluster size is determined by the buffer gas induced beam-broadening technique. For both Ar and N₂ clusters, power variations of the average cluster size with the gas stagnation pressure P ₀ give size scaling as . The average cluster sizes of argon vary from 2950 to more than 30900 atoms per cluster with the argon gas stagnation pressures ranging from 4 to 14 bars, and of nitrogen vary from 600 to more than 10400 molecules per cluster with the nitrogen gas stagnation pressures ranging from 8 to 38 bars. The mixed binary (Ar) _n (N₂) _m cluster is produced by supersonic expansion of an Ar–N₂ mixture. The large mixed binary (Ar) _n (N₂) _m clusters with the average sizes n + m between 1000 and 16000 are obtained. In coexpansion of Ar–N₂ mixture, we find that the argon concentration becomes higher in the beam than before the expansion. This finding is discussed and may be helpful for further insight into the phenomenon of clustering.     

Theoretical investigation of the weakly dihydrogen bonded dimers H2 − nXnAlHHArF and H2 − nXnAlHHKrF (n = 0–2; X = F, Cl)

An ab initio computational study of the properties of the dihydrogen-bonded complexes of H_{2 − n}X_nAlH (n = 0–2; X = F, Cl) with the rare gas (Rg) compounds HArF and HKrF was carried out at the MP2(full)/6-311++G(2d,2p) level of theory. For all the studied complexes, we found a low zero-point corrected binding energies. Large red shifts of the H–Rg vibrational stretching frequency in both complexes were predicted. Electrostatic interactions between the individual monomers are also predicted.     

Structure and stability for (AlN)n+ and (AlN)n+ (n=1–15) clusters

Using density functional theory (DFT) method with 6-31G* basis set, we have carried out the optimizing calculation of geometry, vibrational frequency and thermodynamical stability for (AlN) _n ⁺ and (AlN) _n ⁺ (n=1–15) clusters. Moreover, their ionic potential (IP) and electron affinity (EA) were discussed. The results show that the electrical charge condition of the cluster has a relatively great impact on the structure of the cluster and with the increase of n, this kind of impact is reduced gradually. There are no Al-Al and N-N bonds in the stable structure of (AlN) _n ⁺ or (AlN) _n ^-, and the Al-N bond is the sole bond type. The magic number regularity of (AlN) _n ⁺ and (AlN) _n ^- is consistent with that for (AlN) _n , indicating that the structure with even n such as 2, 4, 6, ... is more stable. In addition, (AlN₁₀ has the maximal ionization power (9.14 eV) and the minimal electron affinity energy (0.19 eV), which manifests that (AlN)₁₀ is more stable than other clusters.     

Origin of the Regioselectivity in the Gas‐Phase Aniline+CH3+ Electrophilic Aromatic Substitution

Nonadiabatic ab initio molecular dynamics simulations are carried out to monitor the attack of CH₃⁺ on aniline in the gas phase to form the corresponding σ complexes. The reaction is ultrafast and is governed by a single electron transfer within 30 fs, which involves two sequential conical intersections and finally produces a radical pair. Positive‐charge allocation in the aromatic compound is found to govern the substitution pattern in ortho, meta, or para position. Although the major products in the first step of the electrophilic aromatic substitution are the ortho and para σ complexes, initially 26 % of the simulated trajectories also form meta complexes, which then undergo H shifts, mainly to the para position.     

Electrochemistry as a correlation tool with the catalytic activities in [RuCl2(p-cymene)(PAr3)]-catalysed Kharasch additions

[RuCl₂(p-cymene)] complexes containing triarylphosphine ligands with various substituents at the para position were used to catalyse the atom transfer radical addition of carbon tetrachloride to various olefins, and their catalytic activities were nicely correlated with their electrochemical parameters.     

Synthesis, spectral and electrochemical study of coordination molecules Cu4OX6L4: 3-cyanopyridine Cu4OBrnCl(6?n)(3-CNpy)4 complexes

New 4-cyanopyridine halide and mixed-halide Cu₄OBr _n Cl_(6−n)(4-CNpy)₄ complexes (4-CNpy = 4-cyanopyridine, n = 0–6) were synthesised, characterised, and studied by infrared spectra, electronic spectra, and cyclic voltammetry. Infrared spectra revealed donor-acceptor vibrational couplings of the Cu₄O, Cu-Cl, and Cu-N stretching vibrations with the in-plane and out-of-plane pyridine ring vibrations. The infrared spectra, electronic spectra, and half-wave potentials correspond to a weak donor and a strong acceptor behaviour of the 4-cyanopyridine ligands and to π-back bonding, Cu(II)→pyridine rings. The results were compared with the related pyridine and 4-substituted pyridine complexes.     

Structures, vibrational frequencies, and electron affinities of SF5On/SF5On (n = 1–3)

The molecular structures, vibrational frequencies, and electron affinities of the SF₅O_n/SF₅O_n⁻ (n = 1–3) species have been examined with four hybrid density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. The SF₅O_n (n = 1–3) species should be potential greenhouse gases. The anion SF₅O₂⁻ with C_s symmetry has a ³A″ electronic state, and the neutral SF₅O₃ with ²A″ electronic state has C_s symmetry. The anions SF₅O₂⁻ and SF₅O₃⁻ should be regarded as SF₅⁻·O₂ and SF₅O⁻·O₂ complexes, respectively. Three different types of the neutral–anion energy separation presented in this work are the adiabatic electron affinity (EA_ad), the vertical electron affinity (EA_vert), and the vertical detachment energy (VDE). The EA_ad values predicted by the B3PW91 method are 5.22 (SF₅O), 4.38 (SF₅O₂), and 3.61 eV (SF₅O₃). Compared with the experimental vibrational frequencies, the BHLYP method overestimates the frequencies, and the other three methods underestimate the frequencies. The bond dissociation energies D_e (SF₅O_n → SF₅O_n−m + O_m) for the neutrals SF₅O_n and D_e (SF₅O_n⁻ → SF₅O_n−m⁻ + O_m and SF₅O_n⁻ → SF₅O_n−m + O_m⁻) for the anions SF₅O_n⁻ are reported.     

Substituent effect in para substituted Cr(CO)5-pyridine complexes

Systematic studies on the substituent effect in para substituted Cr(CO)₅-pyridine complexes have been carried out on the basis of DFT quantum-chemical calculations. Ten simple and mostly common substituents were chosen in order to analyze possibly the largest spectrum of substituent effects. The following substituents were taken into consideration: NO, NO₂, CN, CHO, F, H, CH₃, OCH₃, OH and NH₂. Additionally, the Cr-N and Cr-C bonds were characterized on the basis of Atoms in Molecules topological analysis of electron density. It has been found that the substituents in position 4 of the pyridine ring influence the Cr-N bond of Cr(CO)₅-pyridine complex in a systematic manner, as a result of with, the pyridine moiety has a diversified ability of participating in the interaction with the Cr atom of Cr(CO)₅ moiety. It has also been found, that the electron withdrawing substituents additionally stabilize the Cr-N bond, whereas the electron donating ones weaken it. The substituent effect mainly affects the π-component of the Cr-N bond. This effect proceeds in the whole Cr-pyridine-R moiety, and it is additionally reflected in the corresponding changes in metal-carbonyl bonds, particularly the trans Cr-CO bond.     

Phase diagrams of (R4N)2[Nd(NO3)5]-decane-n-octanol (n-butanol, n-decanol) liquid ternary systems

Phase diagrams on the mole fraction scale are presented for decane- (R₄N)₂[Nd(NO₃)₅]-n-octanol(n-butanol, n-decanol) (1–2–3) ternary liquid systems, where R₄N⁺ stands for trialkylbenzylammonium, at T = 298.15 K. The C₁₀H₂₂-(R₄N)₂[Nd(NO₃)₅] binary system is a two-phase liquid system. One phase (phase I) is the almost neat solvent; the other (phase II) is enriched in (R₄N)₂[Nd(NO₃)₅]. The liquid ternary systems are characterized by homogeneous and two-phase liquid solution fields. One phase is enriched in (R₄N)₂[Nd(NO₃)₅] and n-octanol (n-butanol, n-decanol) and the other in C₁₀H₂₂. The miscibilities in the C₁₀H₂₂-(R₄N)₂[Nd(NO₃)₅] binary system and in the ternary liquid systems were used to calculate, from the equations of the nonrandom two-liquid model (NTRL), intermolecular interaction parameters and excess Gibbs free energies g ^E for the binary and ternary liquid systems along the binodal curve. g ^E > 0 is characteristic of the systems under study, while g ^E decreases in the series of pairs of liquids (1, 2), (1, 3), and (2, 3) Original Russian Text ? A.K. Pyartman, V.A. Keskinov, P.V. Zaitsev, N.A. Charykov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1392–1397.     

An experimental and computational investigation on the fragmentation behavior of enaminones in electrospray ionization mass spectrometry

The dissociation pathways of protonated enaminones with different substituents were investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS) in positive ion mode. In mass spectrometry of the enaminones, Ar? CO? CH?CH? N(CH₃)₂, the proton transfers from the thermodynamically favored site at the carbonyl oxygen to the dissociative protonation site at ipso‐position of the phenyl ring or the double bond carbon atom adjacent to the carbonyl leading to the loss of a benzene or elimination of C₄H₉N, respectively. And the hydrogen? deuterium (H/D) exchange between the added proton and the proton of the phenyl ring via a 1,4‐H shift followed by hydrogen ring‐walk was witnessed by the D‐labeling experiments. The elemental compositions of all the ions were confirmed by ultrahigh resolution Fourier transform ion cyclotron resonance tandem mass spectrometry (FTICR‐MS/MS). The enaminones studied here were para‐monosubstituted on the phenyl ring and the electron‐donating groups were in favor of losing the benzene, whereas the electron‐attracting groups strongly favored the competing proton transfer reaction leading to the loss of C₄H₉N to form a benzoyl cation, Ar‐CO⁺. The abundance ratios of the two competitive product ions were relatively well‐correlated with the σ_p⁺ substituent constants. The mechanisms of these reactions were further investigated by density functional theory (DFT) calculations. Copyright © 2010 John Wiley & Sons, Ltd.     

Interaction of Mn(acac)3 with Asymmetrical Schiff Base Ligands containing an Amido Group

Interaction of asymmetrical Schiff base ligands H₃Lⁿ [where H₃Lⁿ are substituted 3–aza–4–(2–hydroxyphenyl)–N– (2–hydroxyphenyl)but–3–enamide] with Mn(acac)₃ (acac = acetylacetonate) has been investigated. Two different type of manganese(III) complexes have been obtained depending on the nature of the substituents on the ligand. We have found that ligands containing donor substituents drives to the formation of two different kinds of complexes from the same reaction: Mn(Lⁿ)(H₂O)_x ( 1a–5a ) and [Mn(HLⁿ)(acac)](H₂O)_y ( 1b–5b ) (where Lⁿ and HLⁿ signify the ligand in its trianionic and dianionic form, respectively). However, when the substituents are electron withdrawing or poor donor only compounds of the type [Mn(HLⁿ)(acac)](H₂O)_y ( 6–10 ) are obtained. All these compounds have been characterized by elemental analyses, IR and ¹H NMR spectroscopy, FAB mass spectrometry, magnetic measurements and molar conductivities. The electrochemical behaviour of these complexes has also been studied.     

On functionalized fullerenes C 60 X n

Optimal configurations of functionalized fullerenes C ₆₀ X _n for n = 2, 4, 6, 8 have been determined by application of three topological stability measures. It has been found that the optimal configurations with higher n contain optimal configurations with lower values of n. Two stability measures prefer configurations in which functional groups Xs are crowded while the third one points to configurations with isolated pairs of Xs.     

不饱和半夹芯式16e化合物Cp*Ir(S2C2B10H10)与邻、间位取代苯基叠氮的反应性

考虑取代基的位置和电子效应对反应体系的影响, 本文系统地研究了16e化合物Cp^*Ir(S₂C₂B₁₀H₁₀) (1)与邻、间位取代苯基叠氮的反应。研究结果表明：与邻、间位取代苯基叠氮反应均生成苯环邻位碳发生C-H 活化形成C-S 键的金属配合物。这些配合物通过核磁(¹H、¹¹B、¹³C)、红外、质谱、元素分析和单晶结构解析进行了全面地表征。在光照反应结果的基础上, 提出了形成这类产物的自由基机理。     

Synthesis and reactivity of new heterodinuclear iron/rhenium Cx complexes of the formula (η-C5Me5)Re(NO)(PPh3)(CC)n(η-dppe)Fe(η-C5Me5) (n = 3, 4): Redox properties and a dicobalt hexacarbonyl adduct

We report in this communication the synthesis and characterization of two Fe/Re heterodinuclear complexes 3_n of formula (η⁵-C₅Me₅)Re(NO)(PPh₃)(CC)_n(η²-dppe)Fe(η⁵-C₅Me₅) (n = 3, 4) as well as the hexacarbonyl dicobalt adduct (4) of the hexatriynediyl complex 3₃. We show by cyclic voltammetry that the “electronic communication” between the organometallic endgroups and thereby the thermodynamic stability of the corresponding mixed-valent (MV) parent 3_n⁺ is strongly influenced by bridge extension or by complexation of the [Co₂(CO)₆] fragment. In the case of the hexatriynediyl complex, the MV complex 3₃⁺ or 4 can be isolated by performing the chemical oxidation of 3₃ at low temperature. Spectroscopic studies of this compound and of other stable oxidized redox congeners should now help us to unravel how bridge extension modifies the electronic communication between the different redox-active endgroups in this family of unsymmetrically-substituted polyynediyl compounds.