八和九元硼环配位的平面超配位过渡金属钴、铁和镍的理论研究

对一系列潜在的八和九元硼环配位的平面超配位过渡金属，包括单态的1^FeB8^2-，多重态的k^FeB9^n（n=0，k=2；n=-1，k=1），单重态的1^CoB8^n（n=-1，＋1，＋3），多重态的k^CoB9^n（n=＋1，k=2；n=-1，k=1）和单态的1^NiB9^＋，在B3LYP和BP86理论水平下进行了理论计算研究，其几何结构已经被优化为相应势能超曲面局域极小值，电子结构用轨道分析进行了讨论，并用核独立化学位移值对其芳香性进行了预测．计算结果建议所有上述这些具有高对称性的结构是稳定的，并且具有6个π电子，显示有芳香性．     

TiP2^+,TiP4^+,Ti2P4^+二元团簇的理论研究

利用含有电子相关效应校正的密度泛函理论DFT中的B3LYP方法,选择LANL2DZ双ξ基组,并考虑极化函数,对TiP2^+,TiP4^+,Ti2P4^+二元团簇各种可能存在的几何构型及电子结构进行了密度泛函理论研究,得到了TimPn^+二元团族的最稳定构型,其中TiP2^+的最稳定构型为C2v对称性的三角形,TiP4^+的最稳定构型亦具有C2v对称性,Ti2P4^+的最稳定构型为具有D2d对称性的共边双四面体,所得构型很好地说明了激光光解的实验结果。     

不饱和卡宾的单重态与三重态

对X2C=C:和X2C=C=C:(X=H,Li,F)进行了量子化学计算和研究,得到了不饱和卡宾单重态(^1A1)和三重态(^3B1)的几何构型及其相对稳定性随取代基X电负性变化的一般规律,结果表明,不饱和卡宾的基态都是单重态,第一激发态与基态的能量差ΔE(^1A1 - ^3B1)随X的电负性大小而变化,其值一般在60kcal.mol^-^1以内,累积烯基的大小对ΔE(^IA1-^3B1)的影响相对较小,^IA1和^3B1的平衡几何构型并不相同。     

新型多取代硫代半卡巴腙类配体的合成与结构表征

为发展金属离子配体,设计合成了一系列新型多取代氨基硫脲。烯丙基异硫氰酸酯与水合肼溶液反应,制得4-烯丙基氨基硫脲(1)。1分别与联乙酰(2,3-丁二酮)、水合茚三酮、乙二醛反应,合成出联乙酰双缩(4-烯丙基氨基硫脲)(2)、茚三酮-1,3-二缩(4-烯丙基氨基硫脲)(5)、乙二醛二缩(4-烯丙基氨基硫脲)(6)。联乙酰和氨基硫脲反应制备出联乙酰双缩氨基硫脲(3),环己酮与1在无水乙醇中回流反应合成出环己酮缩(4-烯丙基氨基硫脲)(4)。缩合反应操作简便,条件温和,反应时间只需0.5～2h,产物收率达到70%～87%。这些化合物均未见报道,其结构通过元素分析,IR、^1HNMR和MS进行鉴定。初步测试了它们对金属离子的配位性能,这些多取代氨基硫脲配体很容易与Cu^2^+、Co^2^+、Ni^2^+、Zn^2^+、Ag^+、Hg^2^+、Hg^2^+~2及稀土离子形成稳定的螯合物。     

苯二酚异构体双电荷离子和单电荷离子的动能谱研究

本文利用质量分析离子动能谱(MIKES)、碰撞诱导解离(CID)技术和电子捕获诱导解离(ECID)技术, 研究了邻、间、对苯二酚分子在电子轰击质谱(EIMS)中产生的双电荷离子[C6H6O2]^2^+, [C6H4O]^2^+和单电荷离子[C6H6O2]^+。根据测定的电荷分离反应动能释放值T和由此计算出的两电荷间距R, 推测出过渡态的结构。有趣的是, 可利用单电荷离子[C6H6O2]^+的MIKES/CID谱区分苯二酚异构体。     

S2O2分子稳定结构的密度泛函理论研究

采用密度泛函理论中的B3LYP方法,在6-311+G(3df)和Aug-cc-pVTZ水平上,研究了单态S2O2分子的各种可能的异构体及其相对稳定性。结果表明,具有C2v对称性的三角平面分叉异构体的热力学稳定性要高于目前实验上唯一被发现的具有C2v对称性的cis-OSSO异构体,同时trans-OSSO的稳定性与顺式异构体十分接近,这2种异构体应该可以在实验上被观察到。同时本文还讨论了3个最稳定构型的前线分子轨道和链型OSSO的内扭转势能。     

银配合物与联氨定向反应的研究I

本文研究了银的不同配合物与N2H4的反应, 得出微量的Cu^2^+不仅能加快反应速度, 能有效地促进N2H4按反应(4)进行四电子定向反应的比率, 而且N2H4按四电子定向的反应率随银配合物稳4Ag^+(AgL^q^±2)+N2H4 4Ag+N2+4H^+(8L^{q±(-1)]/2) (4)Ag^+(AgL^q^±2)+N2H4 Ag+1/2N2+NH3+H^+(+2L[q±(-1)]/2) (5)定常数的增大而降低的结论。无Cu^2^+时, N2H4的四电子反应率与银配合物的logβ2成线性关系; Cu^2^+存在时, N2H4单电子反应率的对数与1/logβ2呈线性关系。     

二噻啉基二氧化物与镍的络合物[Ni(BiquO2)3]^2^+的立体构型和Ni^2^+的吸收谱

本文通过对[Ni(BiquO2)3]^2^+配位离子中Ni^2^+吸收谱的理论分析, 推导出Ni^2^+的晶场对称性, 以此确定Ni(BiquO2)3X2分子的空间立体结构, 解释这类配合物的电-磁性质和稳定性.     

二噻啉基二氧化物与镍的络合物[Ni(BiquO2)3]^2^+的立体构型和Ni^2^+的吸收谱

本文通过对[Ni(BiquO2)3]^2^+配位离子中Ni^2^+吸收谱的理论分析, 推导出Ni^2^+的晶场对称性, 以此确定Ni(BiquO2)3X2分子的空间立体结构, 解释这类配合物的电-磁性质和稳定性.     

银配合物与联氨定向反应的研究I

本文研究了银的不同配合物与N2H4的反应, 得出微量的Cu^2^+不仅能加快反应速度, 能有效地促进N2H4按反应(4)进行四电子定向反应的比率, 而且N2H4按四电子定向的反应率随银配合物稳4Ag^+(AgL^q^±2)+N2H4 4Ag+N2+4H^+(8L^{q±(-1)]/2) (4)Ag^+(AgL^q^±2)+N2H4 Ag+1/2N2+NH3+H^+(+2L[q±(-1)]/2) (5)定常数的增大而降低的结论。无Cu^2^+时, N2H4的四电子反应率与银配合物的logβ2成线性关系; Cu^2^+存在时, N2H4单电子反应率的对数与1/logβ2呈线性关系。     

Theoretical Studies on Electronic Structures and Spectra for C80^n （D5d,C2v） Singlet

1INTRODUCTIONC80iscalledthemissingfullereneduetoitsinstabilityinkineticsandlowerLUMO-HOMOenergygap[1],aswellasthelowerabundanceintheexperimentandthedifficultyinsynthesis[1~5].However,thestableexistenceofcomplexLa2@-C80[2]stimulatestheresearchinterestinionsofC80.Zhang[3]performedtheoreticalstudiesonthestabi-lityandNMRspectraforC80isomers.Nakao[4]cal-culatedtheLUMO-HOMOenergygapofC80byusingabinitiomolecularorbital.Hennrich[5]syn-thesizedC80(D5)fromfullerenesootextractionbydHPLC.…     

分子价连接性指数中杂原子价点价计算新方法及应用

对分子价连接性指数中杂原子点价δ^v~i的计算方法进行了改进,提出了一种计算杂原子价点价δ^h~i的新方法,认为分子中某一杂原子i的价点价δ^h~i值不仅与它的价层电子数Z~i、最高主量子数n~i以及结合的氢原子数目h~i有关,还与它所在的族烽N~i、陷氢图中连接的其他原子的数目m~i以及杂化方式L~p有关。杂原子i的δ^h~i值与原子i的Pauling电负性具有相近的物理意义。用由δ^h~i构成的分子价连接性指数^nχ^h(n=0,1,2)研究了取代芳烃和烃衍生物的物理化学性质和生物活性,结果表明,^1χ^h比^1χ^v有显著的改善,计算值与实验值接近的程度更高。     

HeLi^n^+(n=0, 1)簇合物的稳定性和垂直激发态光谱

本文用ab initio研究了簇合物HeLi^n^+(n=0, 1)的几何构型和成键性质。在MP2(FULL)/6-31G**, 水平优化所得LeLi^+的平衡键长为0.2062nm, 与实验值0.205nm十分吻合。比较了HeLi^+(X^1∑^+和a^3∑^+), HeLi(X^2∑^+和a^4II)以及HLi(X^1∑^+)的稳定性, 计算了HeLi^+基态的相关能, 势能曲线和垂直激发态光谱。计算采用了6-31G**, 6-311G**,6-311G(2df, 2pd), 6-311G(3df, 2pd)和6-311+G(3df, 2pd)基组; 采用的方法包括MP2(FULL), MP4, MCSCF, MRSDCI, CCD和ST4CCD。计算表明, 同价HeLi^n^+中激发态的离解能均远比基态的大, 其中HeLi^+(a^3∑^+)的离解能最高(60.49kj/mol),说明激发态是稳定束缚态。HeLi^+基态比等电子体HLi分子基态的稳定性小得多。HeLi^+由A^1∑^+到B^1II的垂直跃迁(3σ→1π)振子强度较大而垂直跃迁能较小。     

Quantum chemical and statistical rate study of the reaction of O(3P) with allene: O-addition and H-abstraction channels

The lowest-lying triplet and singlet potential energy surfaces for the O(3P) + CH2=C=CH2 reaction were theoretically characterized using the complete basis set model chemistry, CBS-QB3. The primary product distributions for the multistate multiwell reactions on the individual surfaces were then determined by RRKM statistical rate theory and weak-collision master equation analysis using the exact stochastic simulation method. The results predict that the electrophilic O-addition pathways on the central and terminal carbon atom are dominant up to combustion temperatures. Major predicted end-products for the addition routes include CO + C2H4, 3CH2 + H2CCO, and CH2=C*-CHO + H*, in agreement with experimental evidence. CO + C2H4 are mainly generated from the lowest-lying singlet surface after an intersystem crossing process from the initial triplet surface. Efficient H-abstraction pathways are newly identified and occur on two different electronic state surfaces, 3A' and 3A', resulting in OH + propargyl radicals; they are predicted to play an important role at higher temperatures in hydrocarbon combustion chemistry and flames, with estimated contributions of ca. 35% at 2000 K. The overall thermal rate coefficient k(O + C3H4) at 200-1000 K was computed using multistate transition state theory: k(T) = 1.60 x 10(-17) x T (2.05) x exp(-90 K/T) cm3 molecule(-1) s(-1), in good agreement with experimental data available for the 300-600 K range.     

Clar goblet and related non-Kekulé benzenoid LPAHs. A theoretical study

The results of an ab initio and semiempirical study of Clar Goblet (1), a C(38)H(18) non-Kekulé diradical LPAH, and its constitutional isomers 4 and 5 are reported. Planar D(2)(h)-1 was only 87.4 (triplet) and 83.8 (singlet) kJ/mol less stable than its planar Kekulé isomer C(2)(v)-6 (at (U)B3LYP/6-31G). Planar C(s)-4 was 63.6 (triplet) and 76.5 (singlet) kJ/mol less stable than 6. Overcrowded C(1)-5 was 80.1 (triplet) and 98.1 (singlet) kJ/mol less stable than 6. In concealed non-Kekulé 1, the singlet was more stable then the triplet by 3.6 kJ/mol, while in nonconcealed non-Kekulé 4 and 5, the triplets were more stable than the corresponding singlets by 12.9 and 18.1 kJ/mol, respectively, in accordance with theory. The spin density in 1, 4, and 5 is delocalized throughout the positions corresponding to active peri-peri coupling positions of the radical anion of naphthanthrone (2). The bond lengths in 1, 4, and 5 are in the range expected for aromatic compounds, except for the central carbon-carbon bonds, which are considerably elongated. A certain stabilization is evident in the homodesmotic reaction singlet-1 + 10 + 10 --> 11 + 3 + 3, indicating a "communication" between the two benzo[cd]pyrenyl radical (3) units of diradical 1. The HOMA indices indicate that in both singlet 1 and triplet 1 all of the rings except the central one have a significant aromatic character. The central ring is essentially antiaromatic, having negative HOMA index (-0.140 at UB3LYP/6-31+G). The stabilities of 1(2)(-) and 1(2+) are decreased relative to 3(-) and 3(+), respectively.     

Coupled-cluster study of the electronic structure and energetics of tetrasulfur, S4

Ab initio electronic structure calculations are reported for S4. Geometric and energetic parameters are calculated using the singles and doubles coupled-cluster method, including a perturbutional correction for connected triple excitation, CCSD(T), together with systematic sequences of correlation consistent basis sets extrapolated to the complete basis set limit. The geometry for the ground state singlet C2v structure of S4 is in good agreement with the microwave structure determined for S4. There is a low-lying D2h transition state at 1.6 kcal/mol which interchanges the long S-S bond. S4 has a low-lying triplet state (3B 1u) in D2h symmetry which is 10.8 kcal/mol above the C2v singlet ground state. The S-S bond dissociation energy for S4 into two S2(3Sigma*g) molecules is predicted to be 22.8 kcal mol(-1). The S-S bond energy to form S3+S(3P) is predicted to be 64 kcal/mol.     

Potential energy surfaces, product distributions and thermal rate coefficients of the reaction of O(3P) with C2H4(X1Ag): a comprehensive theoretical study

The potential energy surface for the O((3)P) + C(2)H(4) reaction, which plays an important role in C(2)H(4)/O(2) flames and in hydrocarbon combustion in general, was theoretically reinvestigated using various quantum chemical methods, including G3, CBS-QB3, G2M(CC,MP2), and MRCI. The energy surfaces of both the lowest-lying triplet and singlet electronic states were constructed. The primary product distribution for the multiwell multichannel reaction was then determined by RRKM statistical rate theory and weak-collision master equation analysis using the exact stochastic simulation method. Intersystem crossing of the "hot" CH(2)CH(2)O triplet adduct to the singlet surface, shown to account for about half of the products, was estimated to proceed at a rate of approximately 1.5 x 10(11) s(-1). In addition, the thermal rate coefficients k(O + C(2)H(4)) in the T = 200-2000 K range were computed using multistate transition state theory and fitted by a modified Arrhenius expression as k(T) = 1.69 x 10(-16) x T(1.66) x exp(-331 K/T) . Our computed rates and product distributions agree well with the available experimental results. Product yields are found to show a monotonic dependence on temperature. The major products (with predicted yields at T = 300 K/2000 K) are: CH(3) + CHO (48/37%), H + CH(2)CHO (40/19%), and CH(2)(X(3)B(1)) + H(2)CO (5/29%), whereas H + CH(3)CO, H(2) + H(2)CCO, and CH(4) + CO are all minor (< or =5%).     

A comprehensive theoretical investigation of the electronic states of Ca2 up to the Ca(4s(2) 1S) + Ca(4s5p 1P) dissociation limit

A theoretical survey of the electronic structure of Ca(2) is presented using two-electron pseudopotentials complemented by core-polarization operators on Ca atoms and multireference configuration interaction/quasidegenerate perturbation theory (MRCI/QDPT) treatment of molecular excited states. The spectroscopic constants of 70 electronic states up to 30,000?cm(-1) above the ground state are determined. This implies all Ca(2) states dissociating up to the Ca(4s(2) (1)S) + Ca(4s5p (3,1)P) dissociation limits. All spin states (singlet, triplet, and quintet) are investigated. The work emphasizes the variety of interactions implying singly valence and lowest Rydberg excited states, doubly excited states generated by atom pairs (3)P(4s4p) + (3)P(4s4p), or (3)P(4s4p) + (3)D(4s3d), 4p3d double excitations asymptotically localized on a single-atom. Zwitterionic Ca(+) + Ca(-) configurations are evidenced and shown to induce specific electronic patterns in (1)Σ(g)(+), (3)Σ(g)(+), (1)Σ(u)(+), (3)Σ(u)(+), (1)Π(g), (3)Π(g), (1)Π(u), and (3)Π(u) symmetry manifolds. They also provide insight for qualitative features (barriers) found for the lower electronic states already investigated in previous publications by other authors.     

Trajectory surface hopping study of the O(3P) + ethylene reaction dynamics

Spin-orbit coupling (SOC) induced intersystem crossing (ISC) has long been believed to play a crucial role in determining the product distributions in the O(3P) + C2H4 reaction. In this paper, we present the first nonadiabatic dynamics study of the title reaction at two center-of-mass collision energies: 0.56 eV, which is barely above the H-atom abstraction barrier on the triplet surface, and 3.0 eV, which is in the hyperthermal regime. The calculations were performed using a quasiclassical trajectory surface hopping (TSH) method with the potential energy surface generated on the fly at the unrestricted B3LYP/6-31G(d,p) level of theory. To simplify our calculations, nonadiabatic transitions were only considered when the singlet surface intersects the triplet surface. At the crossing points, Landau-Zener transition probabilities were computed assuming a fixed spin-orbit coupling parameter, which was taken to be 70 cm-1 in most calculations. Comparison with a recent crossed molecular beam experiment at 0.56 eV collision energy shows qualitative agreement as to the primary product branching ratios, with the CH3 + CHO and H + CH2CHO channels accounting for over 70% of total product formation. However, our direct dynamics TSH calculations overestimate ISC so that the total triplet/singlet ratio is 25:75, compared to the observed 43:57. Smaller values of SOC reduce ISC, resulting in better agreement with the experimental product relative yields; we demonstrate that these smaller SOC values are close to being consistent with estimates based on CASSCF calculations. As the collision energy increases, ISC becomes much less important and at 3.0 eV, the triplet to singlet branching ratio is 71:29. As a result, the triplet products CH2 + CH2O, H + CH2CHO and OH + C2H3 dominate over the singlet products CH3 + CHO, H2 + CH2CO, etc.     

Multiple electronic state mechanism for carboryne reaction with benzene: A DFT study

The multiple electronic state mechanisms of the reaction of carboryne with benzene were investigated by M11 calculations. Mechanisms leading to [4 + 2] cycloaddition product P_{4 + 2} , [2 + 2] cycloaddition product P _{2 + 2} , C? C insert product P _C‐Cins and C? H insert product P _C‐Hins were considered. The barrier/stability to structural characteristics correlations revealed that, 1) [2 + 2] addition is a two‐step mechanism which exhibits three electronic state reactivity, and both the addition steps are controlled by the barriers on open‐shell singlet (OSS) potential energy surface (PES); 2) [4 + 2] product P _{4 + 2} is a kinetic product on the experimental condition, and other products should be obtained under more harsher condition. The theoretical results well explain the experimental facts.