Ar-S2(B3 Σ-u →X3 Σ-g)体系跃迁偶极矩的从头计算

采用多参考组态相互作用方法计算了Ar-S2团簇,得到了Ar-S2(X3Σ-g)与Ar-S2(B3Σ-u)的势能曲面;计算并讨论了Ar原子与S2分子的相对位置R与S2(B3Σ-u→X3Σ-g)跃迁矩变化的关系;分析了Ar对S2分子轨道的压缩和诱导偶极矩随R的变化,以及其在高压脉冲快放电激励S2分子激光器实验中对实现S2分子发光的影响.     

复合物C6H5CH3…Ar分子间的外部振动频率

利用双光子共振电离光谱和飞行时间质谱技术在超声分子束中观察到C6H5CH3…Ar的振动光谱.借助同位素光谱效应、内转动能级和分子间振动能级的理论计算,合理地归属了涉及CH3转动和Ar原子振动的光谱,并由此获得复合物分子间各种模式的振动频率.     

Ag3PO4/Ag2S/g-C3N4复合光催化剂的制备与性能

通过沉积法和离子交换法成功地制备了Ag_3PO_4/Ag_2S/g-C_3N_4复合型光催化剂。利用X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、N_2吸附-脱附等温线、紫外-可见漫反射光谱、荧光光谱等手段对样品进行了表征。通过降解罗丹明B考察其可见光催化活性及稳定性,研究了硫化钠与磷酸银物质的量的比值(n_(Na_2S)/n_(Ag_3PO_4))、g-C_3N_4添加量对所制备复合光催化材料性能的影响,同时对光催化机理进行了探讨。结果表明,随着n_(Na2S)/n_(Ag3PO4)的增加,所得复合催化材料活性先增加后降低;当n_(Na2S)/n_(Ag_3PO_4)为1.5%、g-C_3N_4与Ag_3PO_4的质量比为3∶7时制备的催化剂ASC1.5的光催化活性最好,在可见光照射下,40 min内可将罗丹明B完全降解,且5次循环使用后仍保持较高的催化活性。和Ag_3PO_4相比,Ag_3PO_4/Ag_2S/g-C_3N_4复合型光催化材料的活性与稳定性都得到明显提高,这主要归因于复合催化剂比表面积和孔结构的增加,载流子分离效率的提高。光催化机理研究表明,空穴(h~+)、超氧阴离子自由基(·O~(2-))和羟基自由基(·OH)都是光催化过程中的主要活性物种。三者作用大小依次为:h~+·O~(2-)·OH。     

微波硫灯发射光谱的理论模拟

通过实验观测了微波硫灯的发光光谱. 利用从头计算的多组态准简并微扰理论方法, 采用cc-pVQZ基组计算了S2分子B3Σu--X3Σg-态和B″3Πu-X3Σg-态的跃迁矩及其振动态之间跃迁的弗兰克-康登因子, 导出了S2分子振动分辨发射谱. 同时, 利用含时密度泛函方法计算了Sn(n=2~8)分子的吸收谱. 将计算得到的S2分子振动分辨发射谱与实验所测得的光谱分布进行了比较分析, 解释了微波硫灯的宽谱区发光光谱的特性.     

18-冠-6与Eu(fod)3+在CCl4中的化学平衡及其配合物的结构

在室温下测定了CCl_4溶液中,18-冠-6的亚甲基、Eu(fod)的t—丁基质子的PMR化学位移与溶液组成的相互关系。提出了生成配合物RS,R_2S,R_2,R_3(S为18-冠-6,R为Eu(fod)_3)的模式。求得了平衡常数值(升/摩):K_1=[RS]/([R][S])=2.O×10~5,K_2=[R_2S]/([R][RS])=1.0×10~3,Q_1=[R_2]/[R]~2=4.2×10~2,Q_2=[R_3]/([R_2][R])=4.0×10~1。并测得在配合物RS,R_2S中18-冠-6质子的平均化学位移分别为4.90,10.84(ppm,相对于纯18-冠-6); 在配合物R,R_2,R_3,RS,R_2中t-丁基质子平均化学位移分别为1.53,2.33,0.54,1.02,2.42(ppm,相对于TMS)。 根据配合物的化学位移值,并考虑分子及分子轨道的对称性、位阻等因素提出了配合物R_2,RS,R_2S的可能的结构模型。     

CH3F与C2H3反应机理的理论研究

采用密度泛函B3LYP/6-311G(d,p)方法对CH3F与C2H3的反应体系进行了理论研究,获得了反应的势能面信息及可能的微观机理.在QCISD(T)/6-311++G(d,p)水平上精确计算了各反应物种的单点能.结果表明,除抽提氢反应外,标题反应还存在抽提氟(R1)、消氟化氢(R2)、消氢(R3)和自由基形成(R4)四类反应.在QCISD(T)/6-311++G(d,p)//B3LYP/6-311G(d,p)水平上,R1,R2,R3和R4反应的能垒分别是163.9,152.2,209.8和224.2kJ·mol-1,相应反应能为-56.6,-164.3,-2.7和-156.0kJ·mol-1,所有反应均放热,为热力学允许的反应.     

CH3S自由基H迁移异构化及脱H2反应的直接动力学研究

采用密度泛函方法(MPW1PW91)在6-311G(d,p)基组水平上研究了CH₃S自由基H迁移反应CH₃S→CH₂SH (R1), 脱H₂反应CH₃S→HCS＋H₂ (R2)以及脱H₂产物HCS异构化反应HCS→CSH (R3)的微观动力学机理. 在QCISD(t)/6- 311＋＋G(d,p)//MPW1PW91/6-311G(d,p)＋ZPE水平上进行了单点能校正. 利用经典过渡态理论(TST)与变分过渡态理论(CVT)分别计算了各反应在200～2000 K温度区间内的速率常数k^TST和k^CVT, 同时获得了经小曲率隧道效应模型(SCT)校正后的速率常数k^CVT/SCT. 结果表明, 反应 R1, R2 和R3的势垒△E^≠分别为160.69, 266.61和241.63 kJ/mol, R1为反应的主通道. 低温下CH₃S比CH₂SH稳定, 高温时CH₂SH比CH₃S更稳定. 另外, 速率常数计算结果显示, 量子力学隧道效应在低温段对速率常数的计算有显著影响, 而变分效应在计算温度段内对速率常数的影响可以忽略.     

鼓形有机锡氧杂环羧酸簇合物[PhCH2Sn(O)(O2CC4H3S)]6·2CH2Cl2 和 [PhCH2Sn(O)(O2CC3H2NO)]6·2CH2Cl2的合成和晶体结构

利用三苄基氧化锡与2-噻吩甲酸和2-唑甲酸反应,合成了六聚体苄基锡氧2-噻吩甲酸酯(1)和六聚体苄基锡氧2-唑甲酸酯(2)鼓形簇合物.通过元素分析、红外光谱和X射线单晶衍射对其结构进行了表征.测试结果表明:化合物1属三斜晶系,空间群p1,a=1.2760(3)nm,b=1.3056(3)nm,c=1.3343(3)nm,α=105.65(3)°,β=96.27(3)°,γ=97.20(3)°,Z=1,V=2.0997(7)nm3,Dc=1.809g/cm3,μ=2.097mm-1,F(000)=1116,R=0.0651,wR=0.1292.化合物2属三斜晶系,空间群p1,a=1.2240(4)nm,b=1.3673(4)nm,c=1.3744(4)nm,α=107.760(4)°,β=98.069(5)°,γ=91.480(5)°,Z=2,V=2.1631(12)nm3,Dc=3.373g/cm3,μ=3.799mm-1,F(000)=2136,R=0.0382,wR=0.079.它们均为鼓形簇状结构,锡原子呈畸变的八面体构型.化合物1通过分子间S…S近距离作用,形成一维链状结构.     

含桥连Se—Se基团和两个(S2C2B10H10)2-离子的不饱和双核钌化合物与l-乙炔基环己醇的反应性（英文）

在二氯甲烷中,化合物(p-cymene)Ru2(μ-Se2)(S2C2B10H10)2(1)与l-乙炔基环己醇反应得到加成产物(p-cymene)-Ru2(μ-Se2)(S2C2B10H10)2(R1C=CR2)[R1=H,R2=(cyclo-C6H10)(OH)(2);R1=(cyclo-C6H10)(OH),R2=H(3)].化合物2和3在氯仿中加热回流可脱水分别生成4和5,二者在甲苯中进一步加热回流可实现相互转化.所有化合物中,炔烃碳碳三键选择性地加成在两个不同的(S2C2B10H10)2-配体的硫原子[S(2)和S(3)]上,从而使混合价双钌中心RuII/RuIV(18e/16e)转变为单一价态的RuII/RuII(18e/18e),得到进一步稳定的配合物.所有化合物通过元素分析、质谱、核磁共振进行了表征,并解析了化合物2的X衍射单晶结构.     

O3分子在CuO(110)面吸附的密度泛函理论研究

应用密度泛函理论研究了O3分子在2×1 CuO(110)面(S1)和掺杂一个Fe原子的2×1 CuO(110)面(S2)的吸附过程和电子特性. 计算结果表明, O3分子与表面S1和S2有很强的相互作用, O3分子在表面吸附反应的活化能和反应能均为负值, 反应很容易进行. 态密度和电荷密度分析结果进一步证实了O3分子在S1上吸附是桥位化学吸附, 形成表面臭氧化物, 在S2上吸附分解为1个被吸附的表面氧原子和1个自由氧分子. 电子特性分析表明, O3分子与S1和S2相互作用的本质是O3分子的价轨道2p与CuO(110)表面杂化轨道的相互作用.     

The rotational spectrum of the NiS radical in the X3Sigma- state

The rotational spectrum of the NiS radical in the X(3)Sigma(-) state was observed by employing a source-modulation microwave spectrometer. The NiS radical was generated in a free space cell by a dc glow discharge in H(2)S diluted with Ar. The nickel atoms were supplied by the sputtering reaction from a nickel cathode. Rotational transitions with J = 11-10 to 25-24 were measured in the region between 135 and 314 GHz. Rotational, centrifugal distortion and several fine-structure constants were determined by a least-squares analysis. Other spectroscopic parameters such as dissociation energy, vibrational wavenumber and equilibrium bond length were also derived from the determined molecular constants. Excitation energies of the lowest (3)Pi and (1)Sigma(+) states were estimated from the fine-structure constants, lambda and gamma.     

Excitation of XeF* by reactions of XeF2 with Ar(3P0,2),Kr(3P2) and Xe(3P2)

The reactions of the lowest metastable states of Ar, Kr and Xe with XeF₂ were studied in a flowing afterglow apparatus; XeF emission (from D²Π_{$\text{1}\text{2}$} and B ²Π⁺ states) was observed in all cases. The total rate constants (cm³ molecule^?1 s^?1) for XeF^* formation were determined as 75 × 10^?11 ? Xe(³P₂);64 × 10^?11 ? Kr(³P₂) and 20 × 10^?11 ? Ar(³P_0,2). The reactions of Ar(³P_0,2) and Kr(³P₂) with XeF₂ also gave ArF^* and KrF^*, respectively. Analysis of these emissions indicates that at least two different mechanisms are operative: reactive quenching by the ionic—covalent curve-crossing mechanism and excitation transfer. The Ar(³P_0,2 + XeF₂ reaction is a sufficiently strong source of XeF(D—X) emission that the main features of the XeF(D²Π_{$\text{1}\text{2}$} ? X²Σ⁺) system could be photographed and tentative assignments of these vibrational bands are given. The XeF(D → B) emission could not be observed and the ratio of the D—X versus the D—B transition probability must be > 1000 : 1.     

五配位铁硫化合物(Et4N)4〔Fe2(S,X-C6H4-o)4〕的合成与晶体结构

利用无水FeCl与双齿配体Na_2BDT或Na_2MP(Na_2S,X-C,H_4-o_2:X=S,BDT;X=O,MP)在乙醇溶液中反应,然后加入沉淀剂Et_4NBr,可以得到双核铁硫化合物(Et_4N)_2[Fe_(S,X-CH_4-o)_4](1,X=S;2,X=0)。它们分别具有以双硫或双氧桥联起来的五配位扭曲三角双锥构型的铁原子。分子为心对称,核心Fe_2X_2~(2+)为平面。每个铁原子上的二个苯环平面A和B相互近于平行(1,二面角10.1°)或近于垂直(2,二面角100.2°);但铁原子与XSCC平面非共面。Fe原子离平面0.05～0.5A。2是第一个以双齿配位的双氧桥铁硫化合物,它既含有桥基氧原子又具有端基氧原子,对研究含氧配位的铁原子周围环境,为模拟固氧酶中的“P簇”,有一定意义。     

DFT studies on nonlinear optical properties of neutral nest-shaped heterothiometallic [MOS3Py5Cu3X] (M = Mo, W; X = F, Cl, Br, I) clusters

Theoretical calculations were carried out on some neutral nest-shaped heterothiometallic cluster compounds [MOS₃Py₅Cu₃X] (M = Mo, W; X = F, Cl, Br, I) with the high first static hyperpolarizabilities β values. The geometries of these cluster compounds were optimized by the restricted DFT method at B3LYP level with LanL2DZ base set without any constrains. In order to understand the relationship between the first static hyperpolarizabilities and the compositions of these clusters, the frontier orbital compositions and energy gaps between the HOMO and LUMO orbitals were calculated and analysed. In these clusters the HOMO orbitals are mainly composed of halogen atoms and the first static hyperpolarizability increases from F to I atom. The LUMO orbitals of clusters [MoOS₃Py₅Cu₃X] are comprised of Mo, O and S atoms while the LUMO orbitals of clusters [WOS₃Py₅Cu₃X] composed of W atom and pyridine ring. The energy gaps between the HOMO and LUMO orbitals of the clusters [MoOS₃Py₅Cu₃X] are smaller than those of the clusters [WOS₃Py₅Cu₃X]. As a result the first static hyperpolarizability values of the clusters [MoOS₃Py₅Cu₃X] are higher than those of the clusters [WOS₃Py₅Cu₃X].     

SO (B3σ−,A 3Π—X3σ−) Emission from low temperature rare gas—sulfur dioxide afterglows

The emission systems produced in He(2 ³S)/SO₂, Ne(³P_0,2)/SO₂ and Ar(³P_0,2)/SO₂, afterglows have been investigated in the ultraviolet and visible spectral ranges. In all three afterglows we have identified previously unknown long—wavelenght progressions in the SO(A³Π → X ³ σ^?) system and have assigned several new bands in the SO(B ³σ^? → X ³σ^?)system. Reducing the temperature of the helium gas flowing through a hollow cathode discharge source to 118K effectively removes helium ions from the stream, thus facilitating spectral studies in uncontaminated metastable afterglows. A further effect of cooling the rare gases He, Ne, and Ar is an improvement in the resolution of the emission spectra and an enhanced signal-to-noise ratio. bl     

State-resolved dynamics of the CN(B2Sigma+) and CH(A2Delta) excited products resulting from the VUV photodissociation of CH3CN

Fourier transform visible spectroscopy, in conjunction with VUV photons produced by a synchrotron, is employed to investigate the photodissociation of CH3CN. Emission is observed from both the CN(B2Sigma+-X2Sigma+) and CH(A2Delta-X2Pi) transitions; only the former is observed in spectra recorded at 10.2 and 11.5 eV, whereas both are detected in the 16 eV spectrum. The rotational and vibrational temperatures of both the CN(B2Sigma+) and CH(A2Delta) radical products are derived using a combination of spectral simulations and Boltzmann plots. The CN(B2Sigma+) fragment displays a bimodal rotational distribution in all cases. Trot(CN(B2Sigma+)) ranges from 375 to 600 K at lower K' and from 1840 to 7700 K at higher K' depending on the photon energy used. Surprisal analyses indicate clear bimodal rotational distributions, suggesting CN(B2Sigma+) is formed via either linear or bent transition states, respectively, depending on the extent of rotational excitation in this fragment. CH(A2Delta) has a single rotational distribution when produced at 16 eV, which results in Trot(CH(A2Delta))=4895+/-140 K in v'=0 and 2590+/-110 K in v'=1. From thermodynamic calculations, it is evident that CH(A2Delta) is produced along with CN(X2Sigma+)+H2. These products can be formed by a two step mechanism (via excited CH3* and ground state CN(X2Sigma+)) or a process similar to the "roaming" atom mechanism; the data obtained here are insufficient to definitively conclude whether either pathway occurs. A comparison of the CH(A2Delta) and CN(B2Sigma+) rotational distributions produced by 16 eV photons allows the ratio between the two excited fragments at this energy to be determined. An expression that considers the rovibrational populations of both band systems results in a CH(A2Delta):CN(B2Sigma+) ratio of (1.2+/-0.1):1 at 16 eV, thereby indicating that production of CH(A2Delta) is significant at 16 eV.     

Energy transfer in collisions of Ar(3P0,2 metastable atoms with H(2S) atoms. I. Total rate constant and mechanism

The Ar(4s,³P₂) + H(1S,²S) reaction, which gives excited H(n=2) atoms, has been studied. The room temperature rate constant for Lyman-α (2p-1s) excitation was measured as 2.4 × 10^?10 cm³ mol^?1 s^?1. The method was based upon comparison of the Lyman-α emission intensity with the Kr resonance emission intensity produced from Ar(³P₂) + Kr, which has a known rate constant. The H atom excitation, which has a large energy defect of 1.3 eV, is discussed in terms of a curve crossing mechanism.     

Synthesis and structures of the 2-(dimethylsila)pyrimidine derivatives (Ar = Ph, C6H4Bu-4; X = H, SiMe3, Li(hmpa)2, K(thf)3; n = 1, 2)

Five crystalline 2-(dimethylsila)pyrimidine derivatives (Z) have been prepared in excellent 1–4 or satisfactory 5 yield and characterised. The source of each was ultimately Li[CH(SiMe₂R)(SiMe₂OMe)] [R = Me (B) or OMe (I)]. Compound 1 (Z with Ar = Ph, X = SiMe₃, n = 1) was obtained from Z [with Ar = Ph, X = Li(OEt₂), n = 4; previously isolated from B [P.B. Hitchcock, M.F. Lappert, X.-H. Wei, J. Organomet. Chem. 689 (2004) 1342]] and Me₃SiCl. The potassium salt 2 [Z with Ar = C₆H₄Bu^t-4; X = K(thf)₃, n = 2] was made from K[CH(SiMe₃)(SiMe₂OMe)] (C) (via B) and 4-Bu^tC₆H₄CN. Treatment of 2 with 1,2-dibromoethane afforded 3 (Z with Ar = 4-Bu^tC₆H₄; X = H, n = 1); which when reacted with successively n-butyllithium and Me₃SiCl produced 4 (Z with Ar = 4-Bu^tC₆H₄, X = SiMe₃, n = 1). Compound 5 [Z with Ar = 4-Bu^tC₆H₄, X = Li(hmpa)₂, n = 1] resulted from I with 4-Bu^tC₆H₄CN and then OP(NMe₂)₃ (≡ hmpa). Plausible reaction pathways from the appropriate alkali metal alkyl C or I to 2 or 5, respectively, are suggested; these involve regiospecific 1,3-migrations of SiMe₂OMe from C → N and electrocyclic loss of Me₃SiOMe or SiMe₂(OMe)₂, respectively. The X-ray structures of crystalline 1, 2 and 5 are presented.     

Dimethylchalkogenide als liganden in kationischen cyclopentadienyleisen-bis(phosphin)-komplexen: synthese, reaktivität und kristallstruktur von [C5H5Fe(P(OCH3)3)2(S(CH3)2)]PF6

Thermal displacement of coordinated nitriles RCN (R = CH₃, C₂H₅ or n-C₃H₇) in [C₅H₅Fe(L₂)(NCR)]X complexes (L₂ = P(OCH₃)₃)₂, (P(OC₆H₅)₃)₂ or (C₆H₅)₂PC₂H₄P(C₆H₅)₂ (DPPE)) by E(CH₃)₂ affords high yields of [C₅H₅Fe(L₂)(E(CH₃)₂)]X compounds (E = S, Se and Te; X = BF₄ or PF₆). Spectroscopic data and ligand displacement reactions are presented and discussed together with related observations on [C₅H₅Fe(CO)₂(E(CH₃)₂)]BF₄ compounds. The molecular structure of [C₅H₅Fe(P(OCH₃)₃)₂(S(CH₃)₂)]PF₆ was determined by a single-crystal X-ray diffraction study: monoclinic, space group P2₁/n-C⁵_2h (No. 14) with a = 8.4064(12), b = 11.183(2), c = 50.726(8) Å, β = 90.672(13)° and Z = 8 molecules per unit cell. The coordination sphere of the iron atom is pseudo-tetrahedral with an Fe---S bond distance of 2.238 Å.