Photoelectron Spectroscopy and Theoretical Studies of PCSe−, AsCS−, AsCSe−, and NCSe−: Insights into the Electronic Structures of the Whole Family of ECX− Anions (E=N,P, As; X=O,S, Se)

The newly synthesized phosphorus‐ and arsenic‐containing analogues of the thio‐ and seleno‐cyanate anions, PCSe^?, AsCS^?, and AsCSe^?, as well as the known ion NCSe^? were investigated in the gas phase by negative‐ion photoelectron spectroscopy (NIPES), velocity‐map imaging (VMI) spectroscopy, and quantum‐chemical computations. The electron affinities (EA), spin–orbit (SO) splittings, and “symmetric”/“asymmetric” stretching frequencies of the neutral radicals ECX^. (E=N, P, As; X=S, Se), generated by electron detachment from the corresponding anions, were obtained from the spectra. The calculated EAs, SO splittings, and vibrational frequencies are in excellent agreement with the experimental measurements. These newly obtained values, when combined with those previously determined for the lighter analogues, show interesting trends on descending the pnictogen and chalcogen series. These trends are rationalized based on electronegativity arguments, the electron distributions in the HOMOs, and NBO/NRT analyses.     

Encapsulation Chalcogen Anions in Perfluorinated Silicon Fullerene: X2−@Si20F20 (X=O,S, Se)

The structures and stabilities of cage Si₂₀F₂₀ and its endohedral complexes X²⁻@Si₂₀F₂₀ (X=O, S, Se) were determined at the B3LYP/6‐31G(d) levels of density functional theory (DFT). It is found that the adiabatic electron affinity (EA_ad) of host cage Si₂₀F₂₀ (I_h) is higher than that of isolated O atom (4.24 vs. 1.46 eV). This suggests the Si₂₀F₂₀ cage can selectively trap and stabilize the capsulated spherical anions. The calculations predict that X=S and Se are nearly located at the center of the cage, and O dramatically deviates from the center in C_3v symmetry. Moreover, the corresponding X²⁻@Si₂₀F₂₀ complexes have more negative inclusion energies (ΔE_inc) and thermodynamic parameters (ΔZ) than X²⁻@C₂₀F₂₀. The amount of charge that is being transferred from the encapsulated anions to the cage increases with the atomic radius, i.e., from O²⁻ (ca. 45%), S²⁻ (ca. 51%) to Se²⁻ (ca. 59%), and such a novel model of cage may have practical uses as potential and electrical building units of nanoscale materials.     

New heteroorganic betaines containing the (+)E15—C—E14—X(–) and (+)E15—C—E14(–) structural fragments (E15 = P,As; E14 = Si,Ge, Sn; X = C,S, O,NR)

The review surveys the data on the reactions of phosphorus and arsenic ylides with compounds containing E=X bonds (E = C, Si, Ge, or Sn; X = C or S), cyclic oligomers (R₂ES)_n (n = 2 or 3), and heavier analogs of carbenes. These reactions give rise to two new classes of heteroorganic betaines containing the ⁽⁺⁾E¹⁵—C—E¹⁴—X^(–) (I) and ⁽⁺⁾E¹⁵—C—E^14(–) (II) (E¹⁵ = P or As; E¹⁴ = Si, Ge, or Sn; X = C or S) structural fragments. Procedures for the synthesis of these compounds, their reactivities, the X-ray diffraction structures, and the electronic structures established by high-level quantum-chemical calculations are considered in detail. The carbon analogs of betaines of type I, viz., compounds bearing the ⁽⁺⁾P—C—C—X^(–) fragment (III), are also discussed. The latter were long considered as possible intermediates in the reactions of compounds containing the polar C=X bond (X = C, O, S, NR, etc.) with phosphorus ylides (classical Wittig and Corey—Chaykovsky reactions and related processes).     

双核金属茂合物Zn2(η5-E5)2(E=N, P, As, Sb)电子结构和三阶非线性光学性质的理论研究

运用密度泛函PBE0方法研究了双核金属茂合物Zn2(η5-E5)2(E=N, P, As, Sb)的电子结构, 运用自然键轨道(NBO)方法对该体系的电荷分布及成键特征进行了分析. 此类体系中存在Zn—Zn的σ单键, 为近似纯s成分的成键方式. 用含时密度泛函理论(TDDFT ) 完全态求和(SOS) 方法计算了该体系的三阶非线性光学系数, 结果表明, γ值与最大吸收波长λmax成正比, 在各个分量中, 对〈γ〉起主要贡献的是γzzzz, 最大吸收波长对应的电子跃迁是从Zn—Zn的σ成键轨道到Zn—Zn的σ*反键轨道.     

ChemInform Abstract: Probing the Electronic Structure and Aromaticity of Pentapnictogen Cluster Anions Pn5‐ (Pn: P,As, Sb,and Bi) Using Photoelectron Spectroscopy and ab initio Calculations.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

LaX(X=N,P,As,Sb)晶体的能带结构和化学键性质研究

用LMTO-ASA能带程序计算了LaX(X=N,P,As,Sb)晶体的能带结构,得到的晶体能隙分别为LaN_2.30eV,LaP_2.05eV,LaAs_1.66eV,LaSb_1.34eV,与实验结果基本相符.利用价电子总数在阴阳离子上的分配数之比,给出计算晶体化学键性质的经验关系式,根据该式计算晶体化学键的共价性与文献结果非常吻合,说明了该关系式的合理性.     

Theoretical Studies on Structures and Properties of Endohedral Fullerenes Complexes： XHn@C32（X=F,O, N,C; n=l-4）

Theoretical studies on structures and properties of endohedral fullerene complexes formed by encapsulating small molecules of HF, H20, NH3, and CH4 in a C32 fullerene cage, were carried out by ab initio method. Current calculations reveal that these processes to encase them in fullerene are energetically unfavorable because of the small cavity size of C32. The red shift in the F-H stretching frequency indicates the potential existence of hydrogen bonding between the HF molecule and the carbon cage.     

Stability analysis of the neutral noble gas molecules FNgX and their anions FNgX− (Ng = He,Ar, Kr; X = O,S)

The structural stability and bonding energies of the neutral noble gas molecules FNgX and their anions FNgX^? (Ng = He, Ar, Kr; X = O, S) are discussed at the CCSD(T)/aug‐cc‐pVnZ (n = D, T) levels. Results reveal that only two neutral FKrX molecules are stable, whereas their FHeX and FArX counterparts are not. All their anions are stable and the stability mainly derives from the contribution of the extra electron, i.e., the attachment of the electron greatly enhances the orbital interactions of two bonds, F? Ng and Ng? X. Different from the anion counterparts, the electrostatic interaction energy plays a crucial role in the FKrX stability. Compared with those unstable FHeX and FArX counterparts, the enough charge distribution over each atom of FKrX ensures the effective bonding between F and Kr, and between Kr and X, consequently strengthen the stability of the neutral FKrX (X = O, S) structures. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Structures, IR, NMR Spectra and Thermodynamics Properties of Halogenated Compounds X-1-ZB11H10 (Z=O, S, Se;X=F, Cl, Br): A DFT Study

The halogenated compounds of twelve‐vertex closo‐1‐ZB₁₁H₁₁(Z=O, S, Se; X=F, Cl, Br) have unusual stability. The structures of halogenated isomers obtained by DFT method indicate that the halogen atoms are more likely to attack the meta vertexes. The chemical thermodynamic properties show that the halogenations are spontaneous and exothermic. The result that both the optimized and experimental cages of closo‐thiaborane have not changed after chlorination indicates that the substitution of a chlorine atom for a hydrogen atom of closo‐thiaborane happens at outer of the cage. The calculated electronic structures show that the three‐dimensioned aromaticity of cage would like positive chlorine atoms to attack. The halogenations by elemental halogen in the presence of metal halides were proved to belong to the electrophilic substitutions and the mechanism was discussed in details. The suggested transition state interpreted the experiments. The thermal rearrangement which was supposed early according to experiments was verified by the thermodynamic properties of chlorination theoretically. The IR and ¹¹B/¹H NMR isotropic chemical shifts were calculated and compared with the experimental data to reconfirm the structures of chlorinated closo‐thiaborane. Furthermore, the predictions on the halogenated closo‐oxaborane and closo‐selenaborane are significant for the syntheses.     

Photochemical Generation of Chiral N,B,X‐Heterocycles by Heteroaromatic C−X Bond Scission (X=S,O) and Boron Insertion

Chiral organoboron compounds with a chelate backbone and mesityl/heterocycle substituents (thienyl, furyl, and derivatives thereof) undergo a quantitative phototransformation that yields rare, chiral N,B,X‐containing heterocycles, such as base‐stabilized 1,2‐thiaborinines and 1,2‐oxaborinines. Boriranes were observed as intermediates in some of these transformations. The oxaborinines display further reactivity, generating 4a,12b‐dihydrobenzo[h][1,2]oxaborinino[4,3‐f]quinolines through a sequential conrotatory electrocyclization and a [1,5]‐H shift. The N,B,X‐containing heterocycles display strong blue‐green to orange‐red emission in the solid state. Combined DFT//CASP2T calculations suggest that a common biradical intermediate is responsible for the formation of these compounds as well as their interconversion.     

New Organophosphorus Proligands and Amide Precursors: Crystal and Molecular Structures of Ph2P(X)NH(C6H3Pri 2-2,6) (X = O,S) and (OPPh2)(O2SMe)N(C6H3Pri 2-2,6)

The new organophosphorus proligand (OPPh₂)(O₂SMe)NR (R = C₆H₃Prⁱ ₂–2,6) (3) was prepared as a white crystalline solid by reacting the lithiated compound Li[Ph₂P(O)NR] with MeSO₂Cl in a 1:1 molar ratio. The precursor Ph₂P(O)NHR (1), as well as its thio analogue Ph₂P(S)NHR (2), were obtained in the reaction between the lithiated amine RNHLi and the corresponding organophosphorus chloride. All compounds were characterized by multinuclear (¹H, ¹³C, and ³¹P) NMR spectroscopy. The molecular structures of 1–3 were established by single-crystal X-ray diffraction. A zigzag polymeric chain is formed in the crystals of 1 and 2 by hydrogen N–H···X (X = O, S) bonding, while the crystal of 3 contains discrete monomeric units with a syn–syn conformation of the O?P(C)₂–N–S(C)(?O)₂ skeleton.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…     

X-H (X = C, N, O, Si, P, S) 键离解能计算的密度泛函方法研究

使用了不同密度泛函方法计算X-H (X = C, N, O, Si, P, S) 键离解能，并分析不同密度泛函方法的计算精度。研究发现大多数密度泛函方法包括B3LYP, B3P86, B3PW91, G96LYP, PBE1PBE，和BH&HLYP都明显低估键离解能13-25 kJ/mol。该现象与是否使用无限基组无关，因为即使使用无限基组键离解能仍然被低估。因此密度泛函方法不适合用于键离解能的估算。其中B3P86方法的偏差最小。进一步分析表明，使用限制性开壳层计算并无任何优势，在大多数情况下非限制性开壳层计算实际上比限制性开壳层计算要好。最后，我们发现了密度泛函方法对键离解能的低估是系统的，因此建议利用校准后的UDFT/6-311++G(d, p)方法计算化学键离解能。