AlnO2±团簇结构的几何特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法,在6-311G**水平上对AlnO2±(n=1-10)团簇的几何和电子结构进行了理论计算.讨论了混合团簇的基态结构与振动频率,以及电荷转移与分子轨道.结果表明,AlnO2±(n>1)团簇的基态结构都是2个较小的AlmO(m相似文献   

AlnO±2团簇结构的几何特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法,在6-311G**水平上对AInO±2 (n=1-10)团簇的几何和电子结构进行了理论计算.讨论了混合团簇的基态结构与振动频率,以及电荷转移与分子轨道.结果表明,AlnO±2(n＞1)团簇的基态结构都是2个较小的AlmO(m＜n)分子碎片通过Al原子或1个Al4O2局部结构与Al簇相结合形成的.通过对基态结构的能量分析,得到了AlnO±2团簇的稳定性信息.     

Structural, electronic and magnetic properties of ConRh (n=1-8) clusters from density functional calculations

The geometries, stabilities, electronic and magnetic properties of Co_nRh (n=1-8) clusters have been investigated systematically within the framework of the generalized gradient approximation density-functional theory. The results indicate that the most stable structures of Co_nRh (n=1-8) clusters are all similar to those of corresponding Co_n+1 clusters. Maximum peaks of second-order energy difference are found at n=2, 4 and 7, indicating that these clusters possess relatively higher stability than their respective neighbors. The magnetism of the ground state of alloy clusters all displays ferromagnetic coupling except for Co₃Rh. In addition, the doped Rh atom exhibits an important influence on the magnetism of alloy clusters, e.g., compared with corresponding pure Co_n clusters, the local moment of Co atom is noticeably enhanced in Co_nRh alloy clusters at n=1, 2, 5, 6, 7 and 8, while reduced at n=3 and 4. Further analysis based on the average bond length, the charge transfer and the spin polarization has been made to clarify the different magnetic responses to Rh doping.     

Ligand effects on structures and spectroscopic properties of pyridine-2-aldoxime complexes of Re(CO)3(+): DFT/TDDFT theoretical studies

The series of novel rhenium(I) tricarbonyl mixed-ligand complexes Re(X)(CO)(3)(N^N) (N^N = pyridine-2-aldoxime; X = -Cl, 1; X = -CN, 2; and X = -C≡C, 3) has been investigated theoretically to explore the ligand X effect on their electronic structures and spectroscopic properties. The contribution of the X ligand to the highest occupied molecular orbital (HOMO) and HOMO-1 decreases in the order of 3 > 1 > 2, in line with the π-donating abilities of the X: -C≡C > -Cl > -CN. The reorganization energy (λ) calculations show that 1 and 3 will result in the higher efficiency of organic light-emitting diodes than 2. The lowest-lying absorptions of 1 and 3 can be assigned to the {[d(xz), d(yz)(Re) + π(CO) + π(X)] → [π* (N^N)]} transition with mixing metal-to-ligand, ligand-to-ligand, and X ligand-to-ligand charge transfer (MLCT/LLCT/XLCT) character, whereas this absorption at 354 nm (H-1 → L) of 2 is assigned to {[d(xz), d(yz)(Re) + π(CO) + π(N^N)] → [π* (N^N)]} transition with MLCT/LLCT/ILCT (intraligand charge transfer). Furthermore, the absorptions are red-shifted in the order 2, 1, and 3, with the increase of π-donating abilities of X ligands. The solvent effects cause red shifts of the absorption and emission spectra with decreasing solvent polarity.     

A Ru(II) complex with 2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline: synthesis, characterization, and acid-base and DNA-binding properties

A new Ru(II) complex of [Ru(bpy)2(Hmspip)]Cl2 {in which bpy=2,2'-bipyridine, Hmspip=2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} have been synthesized and characterized. The ground- and excited-state acid-base properties of [Ru(bpy)2(Hmspip)]Cl2 and its parent complex of [Ru(bpy)2(Hpip)]Cl2 {Hpip=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline} have been studied by UV-visible (UV-vis) and emission spectrophotometric pH titrations. [Ru(bpy)2(Hmspip)]Cl2 acts as a calf thymus DNA intercalators with a binding constant of 4.0×10(5) M(-1) in buffered 50 mM NaCl, as evidenced by UV-vis and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4-, DNA competitive binding with ethidium bromide, reverse salt titrations and viscosity measurements.     

ConAl (n= 1–8)合金团簇结构和磁性质研究

采用密度泛函理论中的广义梯度近似(DFT-GGA)对Co_nAl (n= 1–8)合金团簇进行了系统的几何、 电子结构和磁性质研究. 研究结果表明Al原子倾向于与Co原子形成最大的成键数, 即Al原子均处在团簇原子拥有最大配位数的位置上. Al掺杂后Co_nAl团簇的稳定性减弱, 磁性降低. 磁性降低的幅度与实验上对较大Co_nAl_M团簇的磁性检测结果获得了很好地符合. 在所有Co_nAl团簇的最稳定结构中, 除Co₄Al外, Al与近邻Co原子均呈现反铁磁性耦合. 相对于纯Co团簇,非磁性Al元素的掺入以及Al掺杂后Co原子整体自旋极化的减弱 是导致Co_nAl团簇磁性的降低主要原因. 关键词： nAl合金团簇')" href="#">Co_nAl合金团簇 几何结构 磁性 自旋极化     

Quantum Chemical Study of CnAl2^± （n=1～10） Clusters： Structure and Stability

Geometries, electronic structures and vibrational frequencies of CnAl2± clusters have been investigated by using the B3LYP-DFT method in the range of n = 1～10. At the B3LYP/6-311G level, the ground state structures of CnAl2± clusters are planar or linear with terminal aluminum atom. In these structures, the C–C bonds are alternately changed between double and triple. The changing magnitude of the averaged bond length decreases with the increase of cluster size. The energetic analysis showed that CnAl2± clusters with even n are more stable than those with odd n.     

Are neutral oxocarbons stable?

A set of novel oligomeric polycyclic neutral oxocarbons has been computed at the B3LYP level of density functional theory. On the basis of the calculated dissociation enthalpies, the most stable structures are C(9)O(9) and C(12)O(12) with benzene-like central ring, in agreement with the experimental finding, and the enhanced stability is due to their aromaticity. Several other oxocarbons also have been identified as stable and are targets for further experimental investigations.     

Neutral bishomoaromatic semibullvalenes

Isolobal substitution of CH units by boron carbonyl groups (BCO) at C2,6 and C2,8,4,6 in semibullvalene favors the delocalized neutral bishomoaromatic systems substantially. The homoaromaticity is documented by the computed diatropic nucleus independent chemical shifts (NICS). In addition, BCO substitution can result in low-lying triplet and open-shell singlet states. In contrast, substitution at C1,5 more than doubles the related Cope rearrangement barrier. The C2,6 and C2,8,4,6 BCO-substituted barbaralanes, barbaralones, and bullvalenes have substantially reduced barriers.     

C_nAl~+小团簇结构的几何特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法,研究了CnAl+(n=2-12)团簇的几何结构与电子性质.在6-311++G**水平上对CnAl+(n=2-12)团簇进行了几何构型优化和振动频率计算.结果表明,CnAl+团簇的基态结构为Al原子与Cn链端基配位形成的直线或折线形结构,以及Al原子与Cn环上1个C原子端位相连或打开Cn环与2个C原子相连形成的环状结构.分子总的平均键长随着n的增大逐渐趋于定值(0.138nm).通过对基态结构的能量分析,得到了CnAl+团簇的稳定性信息.