Charged, but Found "Not Guilty": Innocence of the Suspect Bridging Ligands [RO(O)CNNC(O)OR](2-) = L(2-) in [(acac)(2)Ru(μ-L)Ru(acac)(2)](n), n = +,0,-,2-

Neutral diastereoisomeric diruthenium(III) complexes, meso- and rac-[(acac)(2)Ru(μ-adc-OR)Ru(acac)(2)] (acac(-) = 2,4-pentanedionato and adc-OR(2-) = dialkylazodicarboxylato = [RO(O)CNNC(O)OR](2-), R = tert-butyl or isopropyl), were obtained from electron transfer reactions between Ru(acac)(2)(CH(3)CN)(2) and azodicarboxylic acid dialkyl esters (adc-OR). The meso isomer 3 with R = isopropyl was structurally characterized, revealing two deprotonated and N-N coupled carbamate functions in a reduced dianionic bridge with d(N-N) = 1.440(5) ?. A rather short distance of 4.764 ? has been determined between the two oxidized, antiferromagnetically coupled Ru(III) centers. The rac isomer 4 with R = isopropyl exhibited stronger antiferromagnetic coupling. While the oxidation of the neutral compounds was fully reversible only for 3 and 4, two well-separated (10(8) < K(c) < 10(10)) reversible one-electron reduction steps produced monoanionic intermediates 1(-)-4(-) with intense (ε ≈ 3000 M(-1) cm(-1)), broad (Δν(1/2) ≈ 3000 cm(-1)) absorptions in the near-infrared (NIR) region around 2000 nm. The absence of electron paramagnetic resonance (EPR) signals even at 4 K favors the mixed-valent formulation Ru(II)(adc-OR(2-))Ru(III) with innocently behaving bridging ligands over the radical-bridged alternative Ru(II)(adc-OR(?-))Ru(II), a view which is supported by the metal-centered spin as calculated by density functional theory (DFT) for the methyl ester model system. The second reduction of the complexes causes the NIR absorption to disappear completely, the EPR silent oxidized forms 3(+) and 4(+), calculated with asymmetrical spin distribution, do not exhibit near infrared (NIR) activity. The series of azo-bridged diruthenium complex redox systems [(acac)(2)Ru(μ-adc-R)Ru(acac)(2)](n) (n = +,0,-,2-), [(bpy)(2)Ru(μ-adc-R)Ru(bpy)(2)](k) (k = 4+,3+,2+,0,2-), and [(acac)(2)Ru(μ-dih-R)Ru(acac)(2)](m) (m = 2+,+,0,-,2-; dih-R(2-) = 1,2-diiminoacylhydrazido(2-)) is being compared in terms of electronic structure and identity of the odd-electron intermediates, revealing the dichotomy of innocent vs noninnocent behavior.     

配位不饱和双核钌羰基化合物Ru2(CO)n(n=7,6)的DFT计算研究

对配位不饱和双核钌羰基化合物Ru2(CO)n(n=7,6)在BP86/DZP++和MPW1PW91/DZP++ 理论水平下进行了量子化学理论计算研究, 优化得到16个单态和三态异构体, 并讨论其键的性质. 得到的n=7,6基态分别是Cs和C2v构型的单态, 均含有2个配位的桥羰基. 对其离解能的计算表明, 相对于断裂金属钌-钌键而生成2个配位不饱和单核羰基化合物都更容易失去一个羰基.     

(HAlNH)n(n=2～3)环状化合物的结构特征

用自洽场理论 (HF)和密度泛函理论 (DFT)的B3LYP方法 ,在 6 31G 的水平上对化合物(HAlNH) 2 和 (HAlNH) 3 的几何结构进行优化 ,并分别与环丁二烯C4 H4 和苯分子C6H6的结构和成键方式进行比较。以B3LYP STO 3G方法讨论其分子轨道波函数 (Ψ)。结果表明 :C4 H4 和 (HAlNH) 2 均为D2h对称 ,前者为长方形结构 ,形成两个孤立的π键 ;而后者为菱形结构 ,形成一个π44键。C6H6和 (HAlNH) 3分子点群分别为D6h和D3h,并均形成一个π66键。成键原子对分子轨道的贡献不同 ,其中C原子是完全等价的 ,而Al和N原子各不相同 ,N原子比Al的贡献要大得多     

线性簇合物SC_(2n)S~(2-)(n=1～12)电子吸收光谱

应用密度泛函理论,在B3LYP/6-31G水平上优化了线性簇合物SC2nS2-(n=1～12)的基态平衡几何结构,并计算了它们的谐振动频率.在基态平衡构型下,通过TD-B3LYP/cc-pvTZ和TD-B3LYP/cc-pvDZ计算,确定了簇合物SC2nS2-(n=1～10)X1Σ g→11Σ u电子跃迁的垂直激发能和对应的振子强度.基于计算结果,导出了X1Σ g→11Σ u电子跃迁吸收波长与体系大小n的解析关系式,以及SC2nS2-体系第一电离能与体系大小n的解析表达式,并讨论了不同端位原子对碳链体系激发态性质的影响.     

(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)簇结构及其热力学性质

用HF自洽场理论和密度泛函理论(DFT)的B3LYP方法,在6 31G水平上研究了低聚物(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)簇的几何构型、电子结构和聚合反应热力学性质,比较了两个系列化合物中化学键的强度.结果表明,Cl2AlNH2和H2AlNH2分子为C2 (EC)平面型结构,其中Al－N为由一个σ键和一个键组成的双键.(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)分子为Dnh对称,Al－N是典型的σ单键 .低聚物(Cl2AlNH2)n和(H2AlNH2)n的稳定性顺序分别为: 3 > 2 > 4> 5 > 1和8 > 7 > 9 > 11 > 6.     

饱和烷烃分子C_nH_(2n+2)(n=4-6)的电子动量光谱(英文)

使用B3LYP/TZVP//B3LYP/aug-cc-pVTZ方法系统研究了饱和烷烃分子CnH2n+2(n=4-6)的轨道电子动量光谱,比较了同分异构体CnH2n+2(n=4-6)对轨道动量分布的影响.结合二维空间分析方法对电子在坐标空间中的密度分布进行了系统的研究.计算结果表明,最内价壳层电荷分布主要由s电子贡献,第二近邻芯价壳层则主要由p电子贡献,而其余的价壳层则为sp杂化.最内价轨道表现出最大的谱线强度并且远大于其它轨道的谱线强度,而且正烷烃的谱线强度要大于异烷烃等同分异构体的谱线强度,表现出了明显的与甲基移动的个数有关的性质.     

TinC2n(n=1-6)分子簇的量子化学从头算研究

用量子化学从头计算方法研究了TinC2n(n=1-6)分子簇的几何构型和电子结构。这些TinC2n分子簇以TiC2为结构单元, 通过C-C或Ti-C键进一步连接而逐渐长大。研究结果可以较好地解释实验现象, 并说明Metcars的形成机理。     

[C(AuPH3)m]n+ (m=4-6; n=0-2)成键性质和稳定性研究

用MP2/LanL2DZ方法优化C(AuPH3)4[1a(C4v); 1b(Td)], [C(AuPH3)5]+[2a(C3h); 2b(Cs)]以及[C(AuPH3)6}]2+[3a(C2h); 3b(C2v)]的结构, 得到的几何参数与实验值相符. MP2水平下的自然键轨道(Natural bond orbitals, NBO)分析表明, Au具有d(sp)杂化性质, 其中(sp)具有s-p混合的轨道性质; 沿C-Au辐射方向形成的σ键和切向Au-Au之间的弱吸引相互作用使得整个分子稳定. 化合物1a, 2和3具有2或3个二电子三中心键, 表明该类化合物具有与传统C化学不同的电子结构和立体化学构型.     

CnAl (n=2-11)团簇的结构特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法, 在6-311++G**水平上对CnAl(n=2-11)团簇的几何构型和电子结构进行了结构优化和振动频率计算. 结果表明, n=2的CnAl团簇基态结构为Al原子与两个C原子相连形成的环状结构, n=3-11均为Al原子端基配位的线状结构. 通过对基态结构的能量分析, 得到了n为偶数的CnAl团簇比n为奇数团族稳定的结论.     

7-羟基喹啉-(H2O)n(n=1,2)复合物氢键相互作用的密度泛函理论研究

许多生理过程都通过分子间相互作用来实现。氢键则是最基本的化学作用力之一。具有碱性和酸性双官能团的芳香族化合物能与水作用形成氢键网络,对于实现生物体系的物质转移（质子转移、离子转移）起着十分重要的作用。在非水溶剂中,通过氢键发生质子转移反应动力学实验特征也己进行了广泛的研究。本文用密度泛函B3LYP方法在6-311G^＊基组水平上对7-羟基喹啉-水复合物相互作用进行了研究,从成键特征及氢键复合物的稳定关系方面进行了理论计算。     

SiO2·(CO)n(n=1～2)结构和属性的理论研究

用密度泛函理论详细地研究了SiO2·(CO)n(n=1～2)的结构和属性.研究表明,SiO2·CO是一个T形的具有C2v对称性的分子,SiO2·(CO)2具有C2对称性的分子;频率计算结果与实验值一致,CO在与SiO2成键过程中,C-O伸缩振动频率有所增加,说明静电势在复合过程中起了重要作用;基组重叠误差(BSSE)修正在计算相互作用能时不可忽视,相互作用能和解离能的计算以及NBO分析表明,SiO2·(CO)2中的SiO2与CO之间的作用相对SiO2·CO来说较弱;SiO2和CO2与CO的成键特点不同,主要是缘于SiO2与CO2的能隙不同.     

Generation and characterization of C60(CN)2n−(n=1,2,3)

The mono-anion, di-anion and tri-anion of dicyanodihydrofullerene [C₆₀(CN)₂] have been generated and monitored with a thin-layer spectro-electrochemical cell. The characteristic NIR absorption bands are found to be at 1019, 875 as well as at 744, and 691 nm for C₆₀(CN)₂⁻, C₆₀(CN)₂²⁻ and C₆₀(CN)₂³⁻, respectively. Density functional theory calculations indicate that these anions exhibit no Jahn–Teller effect and possess charge distributions and shape distortions that are different from C₆₀ⁿ⁻(n=1,2,3) upon negative charge addition.     

(CoCr)n (n=1-5)合金团簇的结构和磁性

采用密度泛函理论中的广义梯度近似(GGA)对(CoCr)n (n=1-5)团簇的几何结构、电子结构和磁性进行了系统的研究, 确定了团簇的基态和亚稳态. 结果表明, CoCr二元合金团簇的基态几何构型呈对称有序排列, 其磁性均呈反铁磁性耦合; 团簇键长和配位数的大小对原子局域磁性有很明显的影响; 受Cr原子的影响, 在(CoCr)4团簇中, 非相邻的Co原子之间呈现反铁磁性耦合.     

乙醇-水分子团簇C2H5OH(H2O)n (n=1-9)稳定结构的量子化学研究

采用密度泛函理论B3LYP方法, 在B3LYP/6-311++G(2d,2p)//B3LYP/6-311++G(d,p)基组水平上对乙醇-水分子团簇(C₂H₅OH(H₂O)_n (n=1-9))的各种性质进行研究, 如: 优化的几何构型、结构参数、氢键、结合能、平均氢键强度、自然键轨道(NBO)电荷分布、团簇的生长规律等. 结果表明, 从二维(2-D)环状结构到三维(3-D)笼状结构的过渡出现在n=5的乙醇-水分子团簇中. 此外, 利用团簇结合能的二阶差分、形成能、能隙等性质, 发现在n=6时乙醇-水分子团簇的最低能量结构稳定性较好, 可能为幻数结构. 最后, 为了进一步探讨氢键本质, 将C₂H₅OH(H₂O)_n (n=2-9)最低能量结构的各种性质与纯水分子团簇(H₂O)_n (n=3-10)比较, 结果表明前者与后者中的水分子之间氢键相似.     

CnAl2 (n=1-10)团簇的结构特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法, 在6-311G*水平上对CnAl2 (n=1-10)团簇的几何构型和电子结构进行了结构优化和振动频率计算. 结果表明, 富铝的CAl2团簇基态结构为折线型面状结构, 多碳和双聚体的CnAl2团簇基态结构均为Al原子端基配位的线状结构. 通过对基态结构的能量分析, 得到了n为偶数的CnAl2团簇比n为奇数稳定的结论.     

Assessment of multicoefficient correlation methods, second-order Møller-Plesset perturbation theory, and density functional theory for H3O(+)(H2O)n (n = 1-5) and OH(-)(H2O)n (n = 1-4)

We have assessed the ability of 52 methods including 15 multicoefficient correlation methods (MCCMs), two complete basis set (CBS) methods, second-order M?ller-Plesset perturbation theory (MP2) with 5 basis sets, the popular B3LYP hybrid functional with 6 basis sets, and 24 combinations of local density functional and basis set to accurately reproduce reaction energies obtained at the Weizmann-1 level of theory for hydronium, hydroxide, and pure water clusters. The three best methods overall are BMC-CCSD, G3SX(MP3), and M06-L/aug-cc-pVTZ. If only microsolvated ion data is included, M06-L/aug-cc-pVTZ is the best method; it has errors only half as large as the other density functionals. The deviations between the three best performing methods are larger for the larger hydronium- and hydroxide-containing clusters, despite a decrease in the average reaction energy, making it impossible to determine which of the three methods is overall the best, so they might be ranked in order of increasing cost, with BMC-CCSD least expensive, followed by M06-L/aug-cc-pVTZ. However, the cost for M06-L will increase more slowly as cluster size increases. This study shows that the M06-L functional is very promising for condensed-phase simulations of the transport of hydronium and hydroxide ions in aqueous solution.     

What is the nature of polyacetylene neutral and anionic chains HC(2n)H and HC(2n)H(-) (n = 6-12) that have recently been observed?

The optimized geometries, adiabatic electron affinities, and IR-active vibrational frequencies have been predicted for the long linear carbon chains HC(2n)H. The B3LYP density functional combined with the DZP basis set was used in this theoretical study. The computed physical properties are discussed. The predicted electron affinities form a remarkably regular sequence: 1.78 (HC(12)H), 2.08 (HC(14)H), 2.32 (HC(16)H), 2.53 (HC(18)H), 2.69 (HC(20)H), 2.83 (HC(22)H), and 2.95 eV (HC(24)H). The predicted structures display an alternating triple and very short single bond pattern, with the degree of bond alternation significantly less for the radical anions.     

Joint photoelectron and theoretical study of (Rh(m)Co(n))⁻ (m=1-5, n=1-2) cluster anions and their neutral counterparts

Anion photoelectron spectroscopic experiments and calculations based on density functional theory have been used to investigate and uniquely identify the structural, electronic, and magnetic properties of both neutral and anionic (Rh(m)Co(n)) and (Rh(m)Co(n))(-) (m=1-5, n=1-2) clusters, respectively. Negative ion photoelectron spectra are presented for electron binding energies up to 3.493 eV. The calculated electron affinities and vertical detachment energies are in good agreement with the measured values. Computational results for geometric structures and magnetic moments of both cluster anions and their neutrals are presented.     

(BCO)+n(n=1-12)团簇的结构与稳定性

用密度泛函理论(DFT)的B3LYP方法, 在6-31G*水平上对(BCO)⁺_n(n=1-12)团簇的几何结构、电子结构、振动频率等性质进行了理论研究. 结果表明, (BCO)⁺_n团簇的基态结构均为羰基端配位(μ₁-CO)结构, 且含三元环和五元环数目越多或四元环和六元环的数目越少, 相应的结构越稳定. 能量分析得到, n 为奇数的(BCO)⁺_n团簇比n为偶数的稳定.     

Au-2n(n=1,2)催化CO氧化反应机理的理论研究

采用密度泛函理论B3LYP方法研究了金团簇阴离子Au-2和Au-4催化CO氧化反应的详细机理.计算结果表明,O2分子比CO分子更容易吸附剑金团簇上.第二分子CO能有效降低较强O-O键断裂所需能量.CO氧化反应过程需要两个CO分子协同进行.Au-2和Au-4催化CO氧化反应均通过碳酸根中间体进行,活化能分别为0.607和0.658 eV.Au-4和Au-2都能在常温下有效催化CO氧化反应,这些结果与以前的实验和理论研究一致.