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1.
采用B3LYP/6-31++G(d,p)方法,对内含式化合物X@(HBNH) 12 (X = Li 0/+, Na 0/+, K 0/+, Be 0/2+, Mg 0/2+, Ca 0/2+, H和He)的不同对称性构型进行计算,讨论其最稳定构型的几何参数、包含能、平衡常数、自然电荷、自旋密度、电离势和HOMO-LUMO能隙。发现在X@(HBNH) 12化合物中,客体Na 0/+, K 0/+, Mg 0/2+, Ca 0/2+, H和He几乎处在笼的中心,Li +处在中心附近0.021 nm的半径内,Li和Be 0/2+很大程度上偏离笼的中心位置。Li +, Be 2+, Mg 2+和Ca 2+与其它离子相比,更易嵌入笼内形成稳定的内含式化合物。而且,M@(HBNH) 12 (M = Li, Na,K)的第一电离势比Cs(3.9 eV)原子小,是超碱金属。 相似文献
2.
采用B3LYP/6-31G*方法,对内含式化合物X@B 12P 12(X=Li 0/+、Na 0/+、K 0/+、Be 0/2+、Mg 0/2+、Ca 0/2+、H和He)的不同对称性构型进行了计算,讨论其最稳定构型的几何参数、布居分析、偶极矩、电离势、包含能、振动频率、能隙和自旋密度. 发现在X@B 12P 12化合物中,客体X=Li、Na 0/+、K 0/+、Mg 0/2+、Ca 0/2+和He处在偏离笼的中心0.006 nm的半径内. Be 2+沿着 C3轴偏离中心点0.279 nm. 在Be@B 12P 12和H@B 12P 12的基态结构中,Be和H与笼上的B原子成键. 除Li@B 12P 12、 Be 2+@B 12P 12和He@ B 12P 12外, 其余结构为 Cs对称稳定构型. 相似文献
3.
用DFT的B3LYP方法在6-31G(d)基组的水平上, 对闭式多面体簇合物(HAlNH) 12及其内含式X@(HAlNH) 12和外接式X(HAlNH) 12 (X=F -, Cl -, Br -, O 2-, S 2-, Se 2-)复合物的结构进行了构型优化和能量计算, 并讨论了几何构型、自然键轨道(NBO)、振动频率、能量参数及NMR数据与结构的关系, 最后得到复合物结构的稳定性信息, 具有 Th对称性的X@(HAlNH) 12 (X=F -, Cl -, Br -, S 2-, Se 2-)复合物和具有 C3对称性的O 2-@(HAlNH) 12复合物为内含式的基态结构, 从能量角度分析, 内含式复合物比外接式复合物的结构稳定. 相似文献
4.
研究了复合物Mg +-NCSCH 3在230~440 nm波段和Ca +-NCSCH 3在320~560 nm波段的光解离光谱. 复合物Mg +-NCSCH 3, Ca +-NCSCH 3光诱导反应的产物质谱表明有非反应猝灭产物Mg +(Ca +), C—S键断裂产物Mg +(Ca +)NC 和Mg +(Ca +)NCS以及重排反应产物Mg +(Ca +)-CHSH通道. 在原子跃迁谱线(3 2S→3 2P, 对于Mg +; 4 2S?4 2P, 对于Ca +)的红和蓝两边, Mg +-NCSCH 3的光解离光谱由两个宽峰组成; 而对于Ca +-NCSCH 3, 则是由三个谱峰构成. CIS/6-311++G **等级上, 对应于基态构型的Mg +-NCSCH 3电子态跃迁能量和振子强度与实验光谱较为一致; 而Ca +-NCSCH 3有较大的差别. 这是因为CIS方法忽略电子相关效应, 而Ca +-based的跃迁中3d和4s轨道间存在较强的混合所致. 相似文献
5.
研究了复合物Mg +-NCSCH 3在230~440 nm波段和Ca +-NCSCH 3在320~560 nm波段的光解离光谱. 复合物Mg +-NCSCH 3, Ca +-NCSCH 3光诱导反应的产物质谱表明有非反应猝灭产物Mg +(Ca +), C—S键断裂产物Mg +(Ca +)NC 和Mg +(Ca +)NCS以及重排反应产物Mg +(Ca +)-CHSH通道. 在原子跃迁谱线(3 2S→3 2P, 对于Mg +; 4 2S?4 2P, 对于Ca +)的红和蓝两边, Mg +-NCSCH 3的光解离光谱由两个宽峰组成; 而对于Ca +-NCSCH 3, 则是由三个谱峰构成. CIS/6-311++G **等级上, 对应于基态构型的Mg +-NCSCH 3电子态跃迁能量和振子强度与实验光谱较为一致; 而Ca +-NCSCH 3有较大的差别. 这是因为CIS方法忽略电子相关效应, 而Ca +-based的跃迁中3d和4s轨道间存在较强的混合所致. 相似文献
6.
用DFT的B3LYP方法在6-31G(d)基组的水平上, 对闭式多面体簇合物(HAlNH) 12及其内含式X@(HAlNH) 12和外接式X(HAlNH) 12 (X=F -, Cl -, Br -, O 2-, S 2-, Se 2-)复合物的结构进行了构型优化和能量计算, 并讨论了几何构型、自然键轨道(NBO)、振动频率、能量参数及NMR数据与结构的关系, 最后得到复合物结构的稳定性信息, 具有T h对称性的X@(HAlNH) 12 (X=F -, Cl -, Br -, S 2-, Se 2-)复合物和具有C 3对称性的O 2-@(HAlNH) 12复合物为内含式的基态结构, 从能量角度分析, 内含式复合物比外接式复合物的结构稳定. 相似文献
7.
利用红外和拉曼光谱技术研究了Li +在不同浓度、不同溶剂组成的LiBF 4/ N, N-二甲基甲酰胺-乙腈、LiBF 4/ N, N-二甲基甲酰胺-四氢呋喃电解质溶液中的优先溶剂化现象. 红外和拉曼光谱的分析表明, Li +主要与DMF分子相互作用, 导致该分子的C=O伸缩振动谱带、N—C=O形变谱带、CH 3摇摆谱带等发生了分裂. Li +与其它溶剂分子的相互作用较弱, 谱带的分裂现象并不明显. Li +溶剂化数的计算显示, Li +第一溶剂化层内DMF分子的数目一般大于2, 这说明 Li +在混合溶剂体系内优先与DMF分子相互作用. 量子化学计算支持了这一结论. 相似文献
8.
采用等温溶解平衡法研究了五元体系Na +, K +, Mg 2+//Cl -, NO 3--H 2O在298.16 K、氯化钠饱和时各盐的溶解度和饱和溶液的物化性质(密度, 电导率)以及四元体系Na +, Mg 2+//Cl -, NO 3--H 2O的相平衡关系. 研究表明: 在298.16 K, 氯化钠饱和时该五元体系溶解度相图由六个结晶区、九条单变量溶解度曲线和四个零变量点构成, 六个结晶区分别对应于NaNO 3+NaCl, KNO 3+NaCl, KCl+NaCl, Mg(NO 3) 2•6H 2O+NaCl, MgCl 2•6H 2O+NaCl和复盐KCl•MgCl 2•6H 2O+NaCl; 在298.16 K时, 该四元体系的相图由四个结晶区、五条单变量溶解度曲线和二个零变量点构成, 四个结晶区分别对应于NaNO 3, NaCl, Mg(NO 3) 2•6H 2O, MgCl 2•6H 2O. 相似文献
9.
采用等温蒸发法研究了五元体系Li +, K +//, , -H 2O 在288 K时的介稳相平衡关系, 测定了该五元体系在288 K条件下的介稳平衡的溶解度和溶液密度, 根据实验数据绘制了相应的介稳平衡相图和水图. 相平衡研究结果表明该五元体系介稳相平衡中有复盐K 2SO 4•Li 2SO 4生成, 其介稳相图(Li 2CO 3饱和)有4个共饱和点, 9条单变量曲线, 6个Li 2CO 3饱和的结晶区分别为LiBO 2•8H 2O, K 2B 4O 7•4H 2O, K 2CO 3•3/2H 2O, K 2SO 4, Li 2SO 4•H 2O和复盐 K 2SO 4•Li 2SO 4. 相似文献
10.
采用等温蒸发法研究了四元体系Li +, Na +// SO 42-, CO 32--H 2O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na 3Li(SO 4) 2•6H 2O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li 2SO 4•H 2O, Na 2SO 4, Na 3Li(SO 4) 2•6H 2O, Li 2CO 3, Na 2CO 3•10H 2O. 复盐Na 3Li(SO 4) 2•6H 2O和一水硫酸锂(Li 2SO 4•H 2O)的结晶区较小, 而Li 2CO 3的结晶区最大; 该四元体系介稳平衡条件下未发现Na 2SO 4•10H 2O的结晶区. 相似文献
11.
Using quantum chemistry methods B3LYP/6-31++G(d,p) to optimize endohedral complexes X@(HBNH)12 (X=Li^0/+, Na^0/+, K^0/+, Be^0/2+, Mg^0/2+, Ca^0/2+, H and He), the geometries with the lowest energy were achieved. Inclusion energy, standard equilibrium constant, natural charge, spin density, ionization potentials, and HOMO-LUMO energy gap were also discussed. The calculation predicted that X=Na^0/+, K^0/+, Mg^0/2+, Ca^0/2+, H and He are nearly located at the center of (HBNH)12 cluster. Li^+ lies in less than 0.021 nm departure from the center. Li and Be^0/2+ dramatically deviate from the center. (HBNH)12 prefers to enclose Li^+, Be^2+, Mg^2+, and Ca^2+ in it than others. Moreover, M@(HBNH)12 (M=Li, Na, K) species are "superalkalis" in that they possess lower first ionization potentials than the Cs atom (3.9 eV). 相似文献
12.
Density functional theory calculation was carried out on cation‐π complexes formed by cations [M = H +, Li +, Na +, K +, Be 2+, Mg 2+, and Ca 2+] and π systems of annelated benzene. The cation‐π bonding energy of Be 2+ or Mg 2+ with annelated benzene is very strong in comparison with the common cation‐π intermolecular interaction, and the bonding energies follow the order Be 2+ > Mg 2+ > Ca 2+ > Li + > Na + > K +. Similarly, the interaction energies follow the trend 1‐M < 2‐M < 3‐M for all the metal cations considered. These outcomes may be due to the weak interactions of the metal cations with C? H and the interactions of metal cations with π in addition to the nature of a metal cation. We have also investigated on all the possible substituted sites, and find that the metal ion tends to interact with all ring atoms while proton prefers to bind covalently to one of the ring carbons. The binding of metal cations with annelated benzenes has striking effect on nuclear magnetic resonance chemical shifts using the gauge independent atomic orbital method. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 相似文献
13.
The complexes of Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cations with [N3P3R4O(CH2CH2O)4] (R?=?H(1), NMe2(2), NC(NMe2)2(3)) PNP-lariat ethers were systematically studied in the gas phase by using density functional theory (DFT) B3LYP-D3/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) method. The gas phase cation affinities were calculated to span the wide range between 64.2 and 496.1 kcal mol?1 in order K+?<?Na+?<?Li+?<?Ca2+?<?Mg2+?<?Be2+. The structural and electronic properties of 1–3 and their complexes were investigated and effects of electron-donor substituents were analyzed. The electron-donor substituents were found to promote the cation affinity. Sidearm coordinative interaction with the crown ether-complexed metal ion has been noticed. The nature of the metal–ligand interactions was investigated using Bader’s Quantum theory of atoms in molecule. It has been found that the Be2+–N bonds are partly covalent in nature while other coordinate bonds are of the electrostatic nature. The electron density at the bond critical points was found to be consistent with cation affinity. Natural bond orbital analysis was performed on the optimized geometries. The results showed that the stabilization interaction energies are caused by the donation of O/N lone pair electrons to the LP* orbitals of the metal cations. The amount of charge transfer follows the cation affinity order. The largest charge transfer and associated second-order perturbation stabilization energy were observed for Be2+ complexes. 相似文献
14.
The geometries of the complexes of Li +, Na +, K +, Be 2+, Mg 2+, and Ca 2+ metal cations with different possible 2,6-dithiopurine anions (DTP) were studied. The complexes were optimized at the B3LYP
level and the 6-311++G(d, p) basis set. The interactions of the metal cations at different nucleophilic sites of various possible
2,6-dithiopurine anions were considered. It was revealed that metal cations would interact with 2,6-dithiopurine anions in
a bicoordinate manner. In the gas phase, the most preferred position for the interaction of Li +, Na +, and K + cations is between the N 3 and S 2 sites, while all divalent cations Be 2+, Mg 2+, and Ca 2+ prefer binding between the N 7 and S 6 sites of the corresponding 2,6-dithiopurine. The influence of aqueous solvent on the relative stability of different complexes
has been examined using the Tomasi’s polarized continuum model. The basis set superposition error (BSSE) corrected interaction
energy was also computed for complexes. The AIM theory has been applied to analyze the properties of the bond critical points
(electron densities and their Laplacians) involved in the coordination between 2,6-dithiopurine anions and the metal cations.
It was revealed that aqueous solution would have significant effect on the relative stability of complexes obtained by the
interaction of 2,6-dithiopurine anions with Mg 2+ and Ca 2+ cations. The effect of metal cations on different NH and CS stretching vibrational modes of 2,6-dithiopurine has also been
discussed. 相似文献
15.
In order to predict the extraction ability of 12-crown-4 for different metallic ions, the complexes [M(12-crown-4)] and [M(H 2O) 4] (where M=Li +, Na +, K +, Be 2+, Mg 2+, Ca 2+, Cu 2+ and Zn 2+) were investigated by the density functional theory without restrictions for their geometry. The metal binding capability
was evaluated using the binding energy, and the effect of nature of the metal on the binding properties was also studied.
The results of the calculations showed that the coordination ability of a donor molecule towards different metal ions increased
in proportion to their ionization potential. In addition, based on the extraction distribution coefficient, we found that
12-crown-4 can selectively extract Cu 2+ and Be 2+ ions from aqueous solutions of mixed cations. Obviously, the stability of complexes and the extraction power of extractants
depend greatly on the nature of the metal ions. Calculation results from our study could be used to predict the extraction
power of this crown ether and could play a guiding role in planning experiments. 相似文献
16.
The most stable conformation of ion-molecule complexes involving a CO molecule were surveyed by the use of Hartree-Fock (HF) MO and third-order Moller-Plesset perturbation (MP3) methods with a 6–31G* basis set ion = H +, Li +, Na +, K +, Bc 2+, Mg 2+, and Ca 2+. The MP3 level of theory reveals the ion-CO conformation in which the ion bonds to a carbon atom of CO to be the most stable; these MP3 results are contrary to the HF ones. Binding energies of ion-molecule complexes involving CO and N 2 were computed; MP3 energies are in good agreement with the experimental ones. The computed binding energies of cation-N 2 are about one-third of cation-NH 3 due to the absence of dipole moment and the smaller polarizability of N 2. The decrease in binding energy in cation-CO and -N 2 complexes, with increasing cation size, is mainly caused by the decrease of the electrostatic and polarization stabilizations. 相似文献
17.
The electronic, magnetic, and thermodynamic properties of alkali/alkaline earth metal ion-adsorbed gallium nitride nanocage (Ga 5N 10_NC) have been investigated using density functional theory. The results denote that alkali/alkaline earth-metal ion-adsorbed Ga 5N 10_NC systems are stable compounds, with the most stable adsorption site being the center of the cage ring. The partial density of states (PDOS) can estimate a certain charge assembly between Li +, Na +, K +/ Be 2+, Mg 2+, Ca 2+ and Ga 5N 10_NC which indicate the complex dominant of metallic features as: Ca 2+ > Mg 2+ > Be 2+ >> K + > Na + > Li +. For confirmation of magnetic-alignment of Ga 5N 10_NC, monovalent (M +) and divalent (M 2+) metal ions were added to the sample to measure the effects of metals on the magnetic-alignment properties of Ga 5N 10_NC. Furthermore, the reported results of NMR spectroscopy have exhibited that both M + and M 2+ can be optimized to achieve optimal alignment of nanocage in the presence of an applied magnetic field; however, chemical shift anisotropy spans for Ca 2+– and Mg 2+–containing samples is due to Ca 2+ and Mg 2+ ions binding to Ga 5N 10_NC. Regarding IR spectroscopy, Li +@ Ga 5N 10_NC and Be 2+@ Ga 5N 10_NC with more electronegativity appear the most fluctuations through adsorption process. Moreover, based on NQR analysis, Ca 2+ has shown a different graph of electric potential during trapping in Ga 5N 10_NC compared to other metal cations. Based on the results of amounts in this research, the selectivity of metal ion adsorption by gallium nitride nanocage (ion sensor) has been approved as: K +>Na +> Li + in alkali metals and Ca 2+>Mg 2+> Be 2+ in alkaline earth metals. 相似文献
18.
Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first principles calculations on various cases of Ce 3+ centers in Ca 3Sc 2Si 3O 12 by considering the effects of the charge compensations related to N 3-, Sc 3+, Mn 2+, Mg 2+, and Na +. Firstly, the local structures around Ce 3+ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce 3+ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce 3+-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc 3+ substituting Si 4+. The results show that the first principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors. 相似文献
19.
Endohedral metallofullerenes M@C 24 (M = Li 0/+, Na 0/+, K 0/+, Be 0/2+, Mg 0/2+ and Ca 0/2+) with different spin configurations have been systematically investigated using the hybrid DFT-B3PW91 functional in conjunction with 6-31G(d) basis sets. Our theoretical studies show that Li@C 24, Be@C 24, Be 2+@C 24, and Mg 2+@C 24 are energetically favorable. In these endohedral metallofullerenes, only the encapsulated Be and Ca atoms can donate the electrons to the cage. With exception of Be 2+@C 24, the energy gaps of other charged compounds are larger than that of corresponding neutral compounds. We also find that some endohedral metallofullerenes have high energy gaps, but they are unlikely to show high thermodynamic stability. Additionally, the vibrational frequencies and active infrared intensities are also used as evidence to identify these endohedral metallofullerenes. 相似文献
20.
Optimum geometries and stabilization energies are determined for complexes of H 2O, NH 3, CH 4, C 2H 4, CO, and N 2 with metal cations including Li +, Na +, K +, Rb +, Be 2+, Mg 2+, Ca 2+, Zn 2+, and Al 3+, for the complex (HO) 2PO
2
–
...Mg 2+ and for the complexes of water with F –, Cl –, and Br – by SCF calculations employing the MINI-1 minimal gaussian basis sets. The Boys-Bernardi method was used to evaluate the superposition error. Comparison with the extended basis set results revealed that the MINI-1 set gives uniformly good results for a broad variety of ionic complexes and therefore should be preferred to other small basis sets. 相似文献
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