H3 PAuPh与(H3PAu)2(1,4-C6H4)2光谱性质的密度泛函研究

用密度泛函(DFT)方法优化了配合物H3 PAuPh(a),(H3 Pau)2(1,4-C6 H4)2(b)的基态的几何结构,并用含时密度泛函方法计算了它们的吸收光谱.结果表明配合物a与b的最低能量吸收谱线的波长分别为257.5 nm和307.6nm,皆具有C(2p)→Au(6p)电荷转移参与下的Px(芳环)→px>(芳环)跃迁本质,并伴有Au(5d)→Au(6p)的金属中心电荷转移性质.配合物b是由两个配合物a相连接而成,配合物b的分子轨道也是由配合物a的分子轨道组合而成.由于轨道组合中存在px或Px相互作用,配合物b的最低能量吸收谱线的波长大于配合物a的相应值.     

异构化能量分解分析Ni_2CO_5的(18,18)与(18,16)构型竞争（英文）

本文研究了中性Ni_2CO_5配合物的势能图,发现一个C_(2v)双桥淡基新构型,与以前报道的三羰基桥联的D3h构型竞争Ni_2CO_5的基态结构.尽管三桥式异构体拥有更有利的(18,18)电子构型,即双金属中心都满足18电子规则,中性的Ni_2CO_5配合物更倾向于(18,16)电子结构的双桥式几何.异构化能量分解分析表明,这样的结构优选是静电作用和轨道相互作用极大化的结果.     

[Ru(bpy)2L]2+、 [Ru(phen)2L]2+(L=pytp,pztp)电子结构与抗癌活性研究

对配合物[Ru(bpy)2L]2+、[Ru(phen)2L]2+(L=pytp,pztp),用密度泛函(DFT)法,在B3LYP/LanL2DZ水平上进行理论计算研究.探讨了配合物的电子结构与其抗癌活性的关系,主配体上N原子的增加有利于配合物与DNA的作用,增加配合物的抗癌活性.计算结果显示,对于配合物I～IV,其LUMO轨道能量次序为εI>εII和εIII>εIV;其LUMO的电子云主要分布在主配体上,且分布的含量有I相似文献   

[Ru(MeIm)4L]2+ (L=iip, tip, 2ntz)的电子结构、DNA-键合、构效关系及光谱特征

采用密度泛函的方法,结合导体极化连续模型研究了水溶性二价钌-甲基咪唑类配合物[Ru(MeIm)₄iip]²⁺ (1)、[Ru(MeIm)₄tip]²⁺(2)和[Ru(MeIm)₄2ntz]²⁺ (3)的电子结构、DNA的键合倾向及构效关系．在水溶液中几何优化的基础上分析了配合物的电子结构特征,并合理解释了配合物与DNA的键合倾向．计算结果表明,在主配体上用噻吩代替咪唑取代基可以有效提高配合物与DNA的键合力;同时,在主配体的骨架上引入强电负性的N原子及NO₂基团可以明显降低配合物最低未占据分子轨道能量及前沿分子轨道能量差．基于以上计算结果,预测所设计的配合物3具有最大的DNA键合力常数．另外,详细分析了配合物1、2的构效关系及抗肿瘤作用机理,并预测了配合物3的抗肿瘤活性．最后,用含时密度泛函方法对配合物的电子吸收光谱进行了计算和模拟,并与实验结果进行了对比分析.     

配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O光致发光性能

利用OPO激光激发光谱和三维荧光光谱研究了配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O固体粉末在不同激发光源下的荧光特性,测试了不同浓度配合物水溶液的荧光光谱.固体荧光结果显示该配合物具有很好的荧光性能,当激发光波长为320-400nm时,产生波长分别为400-500nm、580-620nm及690-710nm的三个荧光区;当激发光波长为700-880nm时产生峰值为450nm升频转换荧光,激发光波长为700-800nm时产生峰值分别为590nm和615nm的升频转换荧光.溶液荧光结果表明在10-4-10-2mol/L浓度范围内荧光强度与溶液浓度呈正相关.对其可能的发光机制进行了探讨.     

N,N''-双(3-羧基水杨醛叉缩胺乙基)草酰胺Cu(Ⅱ)-Co(Ⅱ)异双核配合物的密度泛函研究

用密度泛函方法,在ROB3LYP/SDD//ROB3LYP/ANI2MB水平上,对Cu(Ⅱ)-Co(Ⅱ)异双核配合物进行了理论计算,优化得到了它的单、三重态的平衡几何构型,计算了它们的谐振动频率.结果表明:该配合物分子的三重态比单重态稳定,电子自旋布居高度集中在Cu和Co原子上,体系中存在较弱的自旋离城效应.体系的前线分子轨道主要由Cu和Co原子的d轨道和配体原子的p轨道构成,这种构成有利于配体原子与Cu、Co原子之间的电子转移.期望这些研究为这类配合物的合成及分子组装分析研究提供理论参考.     

N,N′-双(3-羧基水杨醛叉缩胺乙基)草酰胺Cu(Ⅱ)-Co(Ⅱ)异双核配合物的密度泛函研究

用密度泛函方法,在ROB3LYP/SDD//ROB3LYP/LANL2MB水平上,对Cu(Ⅱ)-Co(Ⅱ)异双核配合物进行了理论计算,优化得到了它的单、三重态的平衡几何构型,计算了它们的谐振动频率.结果表明:该配合物分子的三重态比单重态稳定,电子自旋布居高度集中在Cu和Co原子上,体系中存在较弱的自旋离域效应.体系的前线分子轨道主要由Cu和Co原子的d轨道和配体原子的p轨道构成,这种构成有利于配体原子与Cu、Co原子之间的电子转移.期望这些研究为这类配合物的合成及分子组装分析研究提供理论参考.     

稀土配合物RE(Et2dtc)3(phen)的光谱性质

以铜试剂(NaEt2 dtc·3H2O)和邻菲咯啉(o-phen·H2O)与水合氯化稀土(RECl3·xH2O)(RE=La,Pr,Nd,Sm～Er;x=3～4)在无水乙醇中反应,制得三元固态配合物RE(Et2dtc)3(phen).IR光谱研究表明配合物中RE3+与NaEt2dtc中的硫原子和o-phen中的氮原子均双齿配位;UV光谱显示配合物中o-phen与稀土离子之间的能量传递是主要过程,配合物的最大吸收与o-phen相比有微小的红移;FS光谱表明配合物Sm(Et2dtc)3(phen)和Eu(Et2dtc)3(phen)分子内能量传递效率高,显示了很强的荧光性质.     

配合物Zn3(NCS)6(L1)6(NO3)2及Ni3(NCS)6(L2)6(NO3)2的合成、光谱表征及荧光性质

以去离子水为溶剂,合成了以Zn2+及N12+为中心,以L1,L2[L1=4-氨基-3,5-二甲基-1,2,4-三唑,L2=4-氨基-1,2,4-三唑]及硫氰酸根为配体的两种配合物,对其进行了元素分析、金属离子络合滴定、摩尔电导测定,确定了配合物组成分别为Zn3(NCS)6(L1)6(NO3)2及Ni3(NCS)6(L2)6(NO3)2,同时对两种配合物做了红外光谱、紫外光谱及荧光光谱的测试表征.荧光光谱的测试表明两种配合物均在415 nm有一强的荧光发射峰,且镍配合物的荧光要明显强于锌配合物,两种配合物有望成为蓝光发光材料.     

{H[Cu(trans-Hcydta)]·2Bzim·1.5H2O·0.5MeOH·HClO4}的合成、结构和量子化学研究

反式 1,2 环已二胺四乙酸与铜离子合成标题配合物 ,经X射线衍射测定配合物的晶体分子结构 ,并用量子化学方法研究配合物的电子结构及分子轨道组成 .该晶体属于单斜晶系 ,空间群为P2 (1) /c ,晶胞参数 :a =1.6 36 0 (6 ) ,b=1.3814 (5 ) ,c=1.5 5 0 3(5 )nm ,β =90 .885 (7) o,V =3.5 0 3(2 )nm3 ,Z =4 ,Dx=1.4 95 g/cm3 ,μ(MoKa) =7.74cm-1,F(0 0 0 ) =16 4 0 ,R1=0 .0 75 0 ,wR =0 .15 2 6 ;配合物中Cu -O键长为 0 .193～ 0 .2 2nm ,中心铜与配基原子形成畸型四棱锥 .     

洁净和氧吸附的Cu(100)表面重构的理论研究

在密度泛函理论下,计算了清洁和吸附氧原子的Cu(100)表面的驰豫和优势吸附构型。结果表明,氧原子在金属表面采用四重穴位时,具有最大的结合能,顶位吸附时结合能最小,桥位吸附时结合能居间。这一计算结果与实验报道一致。各种密度泛函方法的比较后,发现采用mPW1PW91密度泛函和LanL2dz赝势基组,能够准确给出与实验相符的计算结果。平板模型计算的分态密度图显示,在吸附过程中出现d轨道向Fermi能级移动并越过Fermi能级,而O原子的p轨道能级远离Fermi能级,表明有电子从铜原子的d轨道转移到氧原子的2p轨道,簇模型和平板模型的布居分析显示表面氧带有约0.65～0.7 e的负电荷。研究表明,采用适当的基组和泛函方法,即使采用簇模型来模拟表面,也可以获得与实验比较吻合的计算结果。     

苯甲酸分子表面增强拉曼光谱的密度泛函理论研究

基于密度泛函理论,利用量子化学软件,在B3LYP/6-311G**(C,H,S)/Lanl2dz(Ag)水平上对苯甲酸(Benzoic Acid,C7H6O2,BA)进行几何优化,得到BA与Ag原子和Ag离子结合,即C7H5O2-Ag和C7H5O2Ag的平衡构型,在此基础上得到了两种形态的计算拉曼谱图,并和其他文献值进行比较,其中C7H5O2Ag的计算结果与文献中的BA表面增强拉曼光谱的实验值符合得较好。同时采用简正振动分析方法得到其势能分布,从而对其简正振动模式进行了全面归属。     

Valence structures of aromatic bioactive compounds: a combined theoretical and experimental study

Valence electronic structures of three recently isolated aryl bioactive compounds, namely 2‐phenylethanol (2PE), p‐hydroxyphenylethanol (HPE) and 4‐hydroxybenzaldehyde (HBA), are studied using a combined theoretical and experimental method. Density functional theory‐based calculations indicate that the side chains cause electron charge redistribution and therefore influence the aromaticity of the benzene derivatives. The simulated IR spectra further reveal features induced by the side chains. Solvent effects on the IR spectra are simulated using the polarizable continuum model, which exhibits enhancement of the O—H stretch vibrations with significant red‐shift of 464 cm^?1 in 2PE. A significant spectral peak splitting of 94 cm^?1 between O(4)—H and O(8)—H of HPE is revealed in an aqueous environment. Experimental measurements for valence binding energy spectra for 2PE, HPE and HBA are presented and analyzed using outer‐valence Green function calculations. The experimental (predicted) first ionization energies are measured as 9.19 (8.79), 8.47 (8.27) and 8.97 (8.82) eV for 2PE, HPE and HBA, respectively. The frontier orbitals (highest occupied molecular orbitals, HOMOs, and lowest unoccupied molecular orbitals, LUMOs) have similar atomic orbital characters although the HOMO–LUMO energy gaps are quite different.     

Cu(100) (2×22)R45°-O的表面结构与电子态的密度泛函研究

用第一性原理的总能计算研究了Cu(100))面的表面结构、弛豫以及氧原子的(2×22)吸附状 态.计算给出了Cu(100) (2×22)R45°-O吸附表面的结构参数，并得到了上述结构下氧吸附 的Cu(100)表面氧原子和各层Cu原子的电子态密度.计算得到的吸附表面功函数为4.58 eV ，与清洁Cu(100)表面功函数(～4.53 eV)几乎相同.吸附氧原子与最外层铜原子之间的垂直 距离约为0.02 nm，其能带结构体现出一定的金属性，同时由于Cu-O的杂化作用在费米能以 下约6.4 eV附近出现了局域的表面态.可以认为，在Cu(100) (2×22)R45°的氧吸附表面结 构下，吸附氧原子和衬底之间的结合主要来源于表面最外层铜原子与氧原子的相互作用. 关键词： Cu(100)(2×22)R45°-O表面 缺列再构 表面电子态     

Geometric and electronic structures of AlnCum (n = 5–9, m = 1–3) clusters: genetic algorithm combined with ab initio models

The geometries, stabilities and electronic structures of Al _n Cu _m (n?=?5–9, m?=?1–3) clusters were explored by using the genetic algorithm combined with ab initio methods. The geometric structures are almost spherical when the valence electrons are around the magic number 20, otherwise the structures are oblate or prolate. The stabilities of the clusters are related to both the Cu/Al ratios and the electronic configurations. The clusters with lower Cu/Al ratios have high stabilities. The molecular orbitals are in accord with the shell structures predicted by the jellium model. The 3d orbitals of the Cu atoms are localised, although their orbital energies are between the 1P and 1D jellium orbitals. The Al₆Cu₂ with 20 valence electrons forms closed 1S²1P⁶1D¹⁰2S² shells, and shows large binding energy and removal energy, large ionisation potential and small electron affinity. For the no-magic clusters, the structure deformation leads to crystal-field-like splitting of the degenerate shells and stabilises the clusters.     

Density functional theory study of homologous organometallic molecules of the [RhXL2]2 (X = Cl,Br, or I; L = CO,PH3, or PF3) type

Density functional theory generalized gradient approximation calculations, which were tested in our previous detailed study of [RhCl(PF₃)₂]₂ (Seuret et al., 2003, Phys. Chem. chem. Phys., 5, 268–274), were applied for a series of homologous organometallic compounds of the [RhXL₂]₂ (X = Cl, Br, or I; L = CO, PH₃, or PF₃) type. Various properties of the studied compounds were obtained. Optimized geometries of [RhCl(PH₃)₂]₂ and [RhCl(CO)₂]₂ are in very good agreement with available experimental data. Geometries of other compounds as well as other properties (thermochemistry of selected fragmentation channels, barriers to structural changes, frontier orbitals) which are not available experimentally were predicted. All the considered compounds are not planar. Enforcing planarity of the central [RhX]₂ moiety requires only a small energetic cost ranging from 2.2 to 3.9 kcal mol^?1. The analysis of frontier orbitals indicates that the metals provide the most favourable site for the electrophilic attack in all considered compounds. The analysis of the shape of the lowest unoccupied molecular orbitals indicates that the halogens and ligands provide the most favourable site for the nucleophilic attack for [RhCl(CO)₂]₂ or [RhCl(PF₃)₂]. For [RhBr(PF₃)₂]₂, [RhI(PF₃)₂]₂ and [RhCl(PH₃)₂]₂, the nucleophilic attack on the halogen is less probable. Except for [RhCl(CO)₂]₂, the least energetically expensive decomposition channel involves initial separation of ligands. For [RhCl(CO)₂]₂, its decomposition into the RhCl(CO)₂ fragments was found to be the least energetically expensive fragmentation reaction which is probably one of the reasons for the known catalytic activity of this compound.     

Dative versus electron-sharing bonding in N-imides and phosphane imides R3ENX and relative energies of the R2EN(X)R isomers (E = N,P; R = H,Cl, Me,Ph; X = H,F, Cl)*

ABSTRACT

Quantum chemical calculations using density functional theory BP86 and M06-2X functionals in conjunction with def2-TZVPP basis sets have been carried out on the title molecules. The calculation results reveal that the N-imides R₃NNX are always clearly higher in energy than the imine isomers R₂NN(X)R. In the case of phosphane imides R₃PNX and the isomers R₂PN(X)R, the substituent R plays a critical role in determining their relative stabilities. When R is hydrogen or phenyl group, R₃PNX are always higher in energy than R₂PN(X)R but the former are more stable than the latter when R = Cl. Interestingly, the Me₃PNX and Me₂PN(X)Me are quite close in energy. The energy decomposition analysis suggests that the P–N bond in the phosphane imides R₃PNX (R = H, Cl, Me, Ph; X = H, F, Cl) should be described in terms of an electron-sharing single bond between two charged fragments R₃P⁺-NX^? that is supported by (R₃P)⁺←(NX)^? π-backdonation. The π-bond contributes 14–21% of the total orbital interactions while the σ-bond provides 60–68% of ΔE_orb.     

DFT study of dihydrogen interactions with lithium containing organic complexes C4H4-mLim and C5H5-mLim （m = 1, 2）

The interactions of dihydrogen with lithium containing organic complexes C₄H_4-mLi_m and C₅H_5-mLi_m (m = 1, 2) were studied by means of density functional theory (DFT) calculation. For all the complexes considered, each bonded lithium atom can adsorb up to five H₂ molecules with the mean binding energy of 0.59 eV/H₂ molecule. The interactions can be attributed to the charge transfer from the H₂ bonding orbitals to the Li 2s orbitals. The kinetic stability of these hydrogen-covered organolithium molecules is discussed in terms of the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). The results indicate that these organiclithium structures can perhaps be used as building units for potential hydrogen storage materials.     

ELECTRONIC STRUCTURE AND CRYSTALLINE ELECTRIC FIELD IN Rco5(R= Y,La, Ce,Pr, Nd,Sm, Gd,and Tb)

Self consistent charge and spin polarized local spin-density approximation functional theory calculations based on the discrete variational method have been performed for RCo₅(R=Y, La, Ce, Pr, Nd, Sm, Gd, and Tb) compounds. The partial density of states of the Pr atom in the PrCo₆Co₁₂ cluster is established to be strikingly similar to that of the Ce atom in the CeCo₆Co₁₂ cluster, supporting the suggestion that the Pr atom is valence fluctuating. The radii ＜r_4f＞ and ＜r₄f²＞ of the 4f electrons of the R atom from La to Tb, except Ce, show the lanthanide contraction. The crystalline electric field (CEF) parameter A⁰₂ at the R site is calculated using a real charge distribution ρ(R) in the cluster, except for Pr and Nd, and is in agreement with that evalu ated based on the single-ion model. This result shows that the CEF parameter A⁰₂ is mainly determined by the near electronic structure. There exists a hybridization in a certain degree between the light rare-earth R-4f and Co-3d orbitals in some single-electron-molecular-orbitals, which are n ear the Fermi energy level and occupied by electrons. For light rare-earths the R-4f electrons in R Co₆Co₁₂(R=Y, La, Ce, Pr, Nd, and Sm) clu sters are not localized entirely and a small amount of the R-4f electrons have itinerant properties.     

The 4d, 5s,and 5p Orbitals of Rhodium

The 4d, 5s, and 5p orbitals of rhodium have been studied by semiempirical molecular orbital calculations for a Rh2 molecule. Overlap populations, overlap energy, and orbital energies were computed as functions of the orbital exponents of Slater type atomic orbitals. This study was prompted by extremely unsatisfactory results obtained attempting to predict electronic spectra, structure, and bonding in a number of rhodium complexes using analytic atomic orbitals deduced1 from accurate Hartree-Pock(HF) atomic calculations. “These reference calculations considered only the atomic configuration (4d)⁷(5s)² for rhodium.