Theoretical Studies on the Stabilities and Hydrogen Bond Actions of (H_2O)_n Clusters

The stable configurations and hydrogen bond nature of （H2O）n clusters （n = 3-6） have been investigated by the B3LYP method at the 6-31＋＋g^＊＊ level. Upon calculation, four conclusions have been drawn： （1） In the （H2O）3-5 clusters, cyclic configurations were confirmed to be the most stable. But in the （H2O）3-4 ones, only cyclic configurations could be observed. From n = 5 （（H2O）5 clusters）, three-dimensional configuration could be found： （2） In the （H2O）6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; （3） The stable order of （H2O）6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; （4） There exist strong cooperativity and superadditivity in the （H2O）n clusters.

An Extended Cu(Ⅱ) Complex Structure Sustained by Hydrogen Bonding and C-H…π Interactions

The title complex [Cu（L1）（L2）（H2O）]·H2O（1,HL1 = N-（imino（pyridin-2-yl）me-thyl）picolinamidine）,HL2 = salicylic acid） has been obtained by volatilization method with L1 prepared from 2,4,6-tripyridyl-1,3,5-triazine in situ.1 was fully characterized by single-crystal X-ray diffraction,elemental analysis and FT-IR.This complex exhibits a three-dimensional frame-work constructed through hydrogen bonding and C-H···π stacking interactions.The cyclic voltametric behavior of complex 1 was also investigated.1 belongs to the monoclinic system,space group P21/c with a = 15.112（5）,b = 7.115（2）,c = 19.899（6） ,β = 112.32°,V = 1979.4（11） 3,Mr = 460.94,Dc = 1.540 g/cm3,F（000） = 948,μ = 1.146 mm-1,Z = 4,the final R = 0.0612 and wR = 0.1813 for 2510 observed reflections with I 2σ（I）.

The 1:2 Complex of Piperazine with Some Phenols:Hydrogen Bonding Pattern Involved in Transition States in Solution

A novel model for the 1: 2 complex of piperazine with some phenols in solution is established and verified. In CDCl3 solution, one piperazine molecule is tied to two phenol molecules by hydrogen bonds of O-H---N and N-H---O. And the protons of >NH and -OH groups exchange quickly and simultaneously between the atoms of phenol oxygen and piperazine nitrogen.

Investigation of Intermolecular C-H···Halogen Hydrogen Bonded Supramolecular Assemblies in Three Copper(Ⅰ) Complexes Formed by 3,3'-Dimethoxy-6,6'-dimethyl-2,2'-bipyridine Ligand

Three new crystalline compounds 1-3 were successfully obtained by the reactions of 3,3＇-dimethoxy-6,6＇-dimethyl-2,2＇-bipyridine ligand（dmbp） with the corresponding Cu（Ⅰ） salts.Crystal data for 1：orthorhombic Pbca,a = 18.5858（12）,b = 8.1821（5）,c = 20.6066（13） ,V = 3133.7（3） 3,Z = 8,Dc = 1.843 g/cm3,F（000） = 1696,μ = 3.366 mm-1,the final R = 0.0223 and wR = 0.0542.Crystal data for 2：Orthorhombic Pbca,a = 18.7883（16）,b = 8.3249（7）,c = 19.0294（17） ,V = 2976.4（4） 3,Z = 8,Dc = 1.731 g/cm3,F（000） = 1552,μ = 4.154 mm-1,the final R = 0.0279 and wR = 0.0680.Crystal data for 3：monoclinic P21/c,a = 13.812（10）,b = 9.910（7）,c = 23.444（17） ,β = 104.3350（10）°,V = 3090（4） 3,Z = 4,Dc = 1.476 g/cm3,F（000） = 1408,μ = 1.588 mm-1,the final R = 0.0479 and wR = 0.1081.The results of X-ray crystallographic analysis revealed that C14H16ICuN2O2（1） and C14H16BrCuN2O2（2） are isostructural compounds with the dimers connected by C-H···halogen hydrogen bonds to generate a three-dimensional（3D） supramolecular network in 1 and a two-dimensional（2D） sheet structure in 2,respectively,while the mononuclear complex C28H32Cl2Cu2N4O4（3） is ionic.In 3,the [Cu（dmbp）2]＋ cations and [ClCuCl]-anions are connected by C-H···Cl hydrogen bonds to form a one-dimensional（1D） chain along the a axis.Therefore,in the three complexes,the C-H···halogen hydrogen bonds dominate their crystal structures.Additionally,The UV luminescent properties of complexes 1-3 were investigated.

CL-20/HMX共晶与共混物的分子动力学模拟

为比较六硝基六氮杂异戊兹烷(CL-20)/环四亚甲基四硝胺(HMX)的共晶与共混物的性能,分别构建了CL-20∶HMX摩尔比为2∶1的共晶结构及共混物结构。用分子动力学(MD)方法模拟了CL-20/HMX的共晶体系及共混体系的力学性能、结构稳定性及径向分布函数。模拟及计算结果表明:CL-20/HMX共晶工艺能显著改善体系的抗形变能力及延展性。共晶结构的弹性模量要显著大于共混结构。最大键长(L_(max))的排序为:CL-20/HMX共混>ε-CL-20>β-HMX>CL-20/HMX共晶。以范德华力为主的作用力"敏化"了CL-20/HMX共混体系的结构。CL-20/HMX共晶结构的内聚能密度(CED)值要远远大于CL-20/HMX共混结构的CED值。CL-20/HMX共晶体系中存在着长度相对较短CH…O氢键导致其感度较低。

二聚体HX-ClF(X=F,Cl,Br)的结构及其双卤键X…Cl性质的理论研究

使用从头计算方法,以二聚体HX-ClF(X=F,Cl,Br)作为卤键的摸型进行了研究.几何优化计算使用了高精度的CP(counterpoise)修正的分子间势能面(PES)方法,在MP2/6-311++G(3df,3pd)水平,得到了二聚体HX-ClF,(X=F,Cl,Br)的三个稳定结构.在三个二聚体HF-ClF,HCl-ClF和HBr-ClF的结构中存在着两种分子间相互作用——双卤键X…Cl和氢键H…Cl.二聚体HX-ClF的X…Cl键长顺序是:2.758(HF-ClF)<3.145(HCl-ClF)<3.212(HBr-ClF),它们的H…Cl键长分别是3.301(HF-ClF)、3.471(HCl-ClF)和3.554(HBr-ClF).用高水平的CCSD(T)/6-311++G(3df,3pd)计算的相互作用能分别是:-2.15kcal/mol(HF-ClF)、-1.54kcal/mol(HCl-ClF)和-1.64kcal/mol(HBr-ClF).计算结果表明,相互作用能的电子相关效应是重要的.由于相互作用能的电子相关效应随着电子给予体原子F、Cl、Br的顺序增大,从而,二聚体HBr-ClF的X…Cl相互作用能也相应地被增大.

Cooperative C–H…O H-bonds in ‘Bay Area’and Crystal Structure of 1-(4-Methylphenyl)-3-(4-methoxyphenyl)-2-propene-1-one

The title compound (C17H16O2, Mr = 252.30) crystallizes in the monoclinic system, space group P21/c with a = 11.5763(14), b = 11.0321(11), c = 11.5094(13) ?, β = 114.581(3)o, V = 1336.7(3) ?3 , Z = 4, Dc = 1.254 g/cm3, μ(MoKa) = 0.081 cm-1 and F(000) = 536.00. The final R and wR are 0.0527 and 0.1285, respectively for 3058 observed reflections (I > 2σ(I)). In the title molecule, two phenyl rings are rotated oppositely with respect to the central part C(1)–C(2)=C(3)– C(4) (plane 3) and the dihedral angle between them is 14.8o. The phenone O(1) atom deviates from plane 3 by 0.291 ?. In the crystal the molecules form H-bond chains of R2 (6) and R2 (5) types 1 1 along [001]. The molecule chains interacted through three cooperative C–H…O H-bonds (R3 (11)) 1 in the ‘bay area’ (Fig. 3), extending along [010] and forming layer (100). Between the layers, there exist C–H/π interactions along [101]. Studies on the cooperative C–H…O H-bonds R3 (11) in the 1 similar crystals are also presented.

A Proton Nuclear Magnetic Resonance (¹H NMR) Investigation of NaCl-Induced Phase Separation of Acetonitrile-Water Mixtures

The microscopic properties of NaCl-induced phase separation of acetonitrile (ACN)-water mixtures have been studied by proton nuclear magnetic resonance (1H NMR). Acetonitrile-rich phase increases with increasing NaCl concentration (cNaCl) at xACN ≈ 0.25. 1H chemical shift of water for acetonitrile-rich phase rapidly decreases with decreasing NaCl mole concentration and that for water-rich phase quickly increases with increasing cNaCl. However, 1H chemical shift of acetonitrile has nothing to do with the molar concentration of NaCl, and it keeps relatively stable for all solutions (±0.002). These results reveal that Na+ and Cl- are rapidly hydrated by water, not by acetonitrile. The change of 1H chemical shift of water has shown that the number of hydrogen bond increases or hydrogen bond strengths with increasing NaCl molarity in mixtures. But hydrogen bond is broken or weaken with the temperature rising. 1H chemical shifts of pure water and the water in acetonitrile-rich phase have been investigated at 293 K, 298 K and 303 K. The hydration number of Na+ (6.05) in water-rich phase is determined by an empirical equation involving 1H chemical shift, temperature and NaCl molarity, which is in good agreement with the literatures.

Syntheses,Characterization and Crystal Structures of Dithiocarbamate-based Mononuclear Palladium(Ⅱ) Complexes

By employing the dithiocarbamate salt （K（PPDC）, where PPDC = 4？-pyridyl-1-pipe-razine-4-dithiocarbamate） as the functional ligand and di-palladium complexes [（N^N）2Pd2（NO3ˉ）2]（NO3ˉ）2 （N^N = 2,2＇-bipyridine, bpy; 4,4＇-dimethylbipyridine, dmbpy） as corner, two novel single metal complexes with Pd（II） centers have been obtained. These organic-metal complexes were characterized by NMR, ESI-MS, elemental analysis, Uv-vis spectra and single-crystal X-ray diffraction analysis. Compound 1？（PF6）2 （[（bpy）Pd（PPDC）]·（PF6）2） crystallizes in triclinic, space group P , a = 8.3968（5）, b = 11.5565（7）, c = 18.2234（11）, α = 97.505（1）, β = 91.424（1）, γ = 106.146（1）o, C22H24N6S2P2F12Pd, Mr = 832.93, V = 1680.58（18） ？3, Z = 2, Dc = 1.646 Mg/m3, μ（MoKα） = 0.863 mm-1, F（000） = 828, the final R = 0.0455 and wR = 0.1390 for 6981 observed reflections with I 〉 2σ（I）. Similarly, compound 2？（PF6）2 （[（dmbpy）Pd（PPDC）]·（PF6）2） also crystallizes in triclinic, space group P , a = 13.9467（3）, b = 14.8390（2）, c = 17.0632（3） ？, α = 81.8680（10）, β = 87.051（2）, γ = 83.4590（10）o, C22H25N5S2P2F12Pd, Mr = 819.93, V = 3470.81（11） ？3, Z = 4, Dc = 1.569 Mg/m3, μ（CuKα） = 7.115 mm-1, F（000） = 1632, the final R = 0.0606 and wR = 0.1637 for 12835 observed reflections with I 〉 2σ（I）. Crystallography reveals that each metal center coordinates with two N atoms from bpy and two S atoms from PPDC in the square coordination mode. In the crystal structure of complex 1, a weak Pd……Pd interaction can be observed. Interestingly, it was also found that the mononuclear moieties of complex 2 could be packed into a 3-D porous framework via multiple intermolecular C–F……H hydrogen-boding interactions which extended in the a, b, and c axes with PF6ˉ anions frozen inside.

一种新1H-1,2,3-三唑-4-甲酰胺化合物的合成、晶体结构和氢键研究

合成了一种新的5-甲基-N,1-(二-对甲苯基)-1H-1,2,3-三唑-4-甲酰胺化合物并研究了晶体结构和氢键构成.通过元素分析、核磁共振、质谱、红外光谱对目标化合物进行了表征.化合物的化学式为C_(18)H_(18)N_(4)O,Mr=306.36,晶体属于单斜晶系P21/c空间群中,其晶胞参数为a=1.03251(3)nm,b=0.74042(2)nm,c=2.11902(6)nm,α=90°,β=99.1250(10)(°),γ=90°,V=1.59947(8)nm^(3),Dx=1.272 g5cm^(-3),Z=4.最终R值为0.0429.对目标化合物的芳香体系和氢键体系进行了讨论,并展示了分子晶体在不同平面方向的密堆积.

C_6H_5—H…X分子间氢键的理论计算

利用密度泛函理论B3LYP方法,在6-311+G(3df,2p)水平上对C6H5—H…X型分子间氢键进行了几何构型优化、氢键相互作用能、电子密度分布等计算.其中C6H6为质子供体,HCOH、H2O、NH3、CH2NH和HCN为质子受体.从电荷布居分析、自然键轨道等角度详细地讨论了C6H5—H…X体系中,共轭π键、O和N的不同键型结构对氢键形成的影响以及孤电子对与C—H反键轨道之间的相互作用(n→ó*)等.

六氢吡啶和氨形成的氢键团簇C_5H_(10)NH(NH_3)_n(n=1～3)结构的从头算研究

在 RHF/6 - 31G( d)水平下 ,对 C5 H10 NH( NH3) n( n=1～ 3)氢键团簇的平衡构型进行了从头算研究 ,优化得到各种可能的平衡构型 .C5 H10 N H( N H3)为线型氢键结构 ,而 C5 H10 N H( NH3) 2 为三元环结构 ,C5 H10 NH( NH3) 3为四元环结构 .在 MP2 /6 - 31G( d) //B3LYP/6 - 31G( d)水平下 ,对最稳定构型 C5 H10 NH( NH3) n( ) ( n=1～ 3)的分子轨道进行布居分析 ,并且对相应的占据轨道进行指认 .C5 H10 NH( NH3) n( )( n=1～ 3)垂直电离势的计算结果表明 ,形成氢键团簇后 ,分子的垂直电离势降低 .

三接触弯曲构型的蓝移氢键CH_3…Y的理论研究

运用量子化学从头算方法,在MP2/6-311++G(d,p),MP2/6-311++G(2df,2p),MP2/6-311++G(3df,3pd)和QCISD/6-311++G(d,p)水平上,研究了CH3F,CH3Cl和CH3Br作为质子给体与Cl-,Br-作为质子接受体形成的氢键CH3…Y.计算结果表明:6种复合物中C—H键收缩,伸缩振动频率增大,形成蓝移氢键.分子中原子(AtomsinMole-cules,AIM)分析表明,这些复合物的电子密度拓扑性质与普通氢键有着本质的不同,在Y…H之间不存在键临界点,而在Y与C之间存在键临界点,因此这些相互作用严格地不能称为氢键.自然键轨道(Natural bond orbital,NBO)分析表明,在这些复合物中弯曲的CH…Y的特殊结构使得分子间超共轭n(Y)→σ*(C—H)减小到可以忽略;质子接受体的电子密度没有转移到σ*(C—H)上,而是转移到了σ*(C—X)(X=F,Cl,Br)上;存在一定程度的重杂化;分子内超共轭相互作用减小使得σ*(C—H)的电子密度减少.这些因素共同导致C—H伸缩振动频率的蓝移.

C_6H_5O─H…X分子间氢键的理论研究

在B3LYP/6-311++G(3df,2p)理论水平上,对C6H5O─H…X(X=H2O、HCOH、CH3COCH3、NH3、CH2NH、HCN)氢键体系进行几何结构优化与振动频率计算,利用计算所得的稳定构型,在相同基组水平上进行自然键轨道(NBO)分析,同时应用AIM 2000程序计算6个复合物中氢键临界点的拓扑参数.结果表明,C6H5O─H…X体系存在较强的O─H…O与O─H…N氢键,氢键的形成使H─O伸缩振动频率明显红移.氢键相互作用的稳定化能主要来源于O、N原子的孤对电子和电子受体C6H5OH中参与形成氢键的O─H反键轨道相互作用.AIM分析得到C6H5O─H…X复合物中氢键相互作用以静电作用占主导地位.

芳氢与配位硫原子之间(sp^2C—H…S)的分子内氢键

化合物（Ｅｔ４Ｎ）２［Ｐｄ２（ｍｐ）２（Ｈｍｐ）２］（１）（Ｈ２ｍｐ＝２－巯基苯酚）的１ＨＮＭＲ谱中芳氢Ｈ１６的峰出现在δ８．７９处，与预测值（δ７．１）相差１．７，这是由于Ｈ１６与配位硫Ｓ２原子之间存在弱相互作用，即新型的ｓｐ２Ｃ—Ｈ…Ｓ之间的氢键作用．原子间距离Ｃ１６…Ｓ２（０．３６１ｐｍ）和Ｈ１６…Ｓ２（０．２９５ｐｍ）分别小于相应原子的范德华半径之和（０．３７０ｐｍ和０．３０５ｐｍ），Ｃ１６—Ｈ１６…Ｓ２角为１２８．１°，证明了这种新型氢键的存在．此外，在分子振动光谱中观察到这种氢键的作用使得芳氢νＣ—Ｈ出现在低于３０００ｃｍ－１处．通过与类似物［Ｐｄ２（ＰＰｈ３）２（Ｈｍｐ）２Ｃｌ２］（２）的比较，以及１在ＤＭＳＯ溶剂中仍然保持Ｏ—Ｈ…Ｏ和Ｃ—Ｈ…Ｓ这２种氢键的事实，表明Ｃ—Ｈ…Ｓ之间的作用，对１的配体Ｈｍｐ中的苯环与Ｐｄ２Ｓ２平面之间的夹角偏离９０°可能是有贡献的．

衬底温度对nc-Si:H薄膜微结构和氢键合特征的影响

采用射频等离子体增强型化学气相沉积(RF-PECVD)技术,以H2和SiH4作为反应气体源,在不同的衬底温度下沉积了nc-Si∶H薄膜。采用Raman散射、X射线衍射、红外吸收等技术分析了薄膜的微结构和氢键合特征。结果表明,随衬底温度的升高,nc-Si∶H薄膜的沉积速率不断增大,晶化率和晶粒尺寸增加,纳米硅颗粒呈现出Si(111)晶面的择优生长趋势。键合特性显示,薄膜中的氢含量随衬底温度升高而逐渐减小,薄膜均匀性先增大后减小。

HMX/DMF溶剂化物结构和分子间相互作用的理论研究(英文)

采用量子化学计算和分子动力学(MD)模拟,研究了溶剂化物环四亚甲基四硝胺(HMX)/N,N-二甲基甲酰胺(DMF)的结构和分子间相互作用。对浸渍在DMF溶剂中的β-HMX分子的MD模拟表明,HMX的分子构象已经从β转变为α相。在M P2/6-31G*水平上的理论计算也说明,在D M F溶剂中,α-HM X比β-HM X更稳定。这解释了在HM X/D M F溶剂化物的多晶型中,所有的HMX分子均呈α构象的原因。采用MP2/6-31G*方法,对α-HMX和DMF分子间可能的同型和异型二聚体进行结构优化。结果表明,组分间存在C—H…O氢键相互作用,并且α-HMX/DMF的稳定化能非常接近α-HMX/α-HMX,并远远大于D M F二聚体的。这意味着异型分子间力可和同型分子间力竞争。从热力学的观点来看,共结晶过程可能发生。对α-HM X在D M F中的过饱和溶液的M D模拟表明,分子间相互作用对共结晶有利。这些理论研究对理解在HM X的D M F溶液中为什么发生的是共结晶而不是重结晶提供了有价值的信息。

金属碳、卡宾阳离子[M—X]^+(M=Au,Ag,Cu;X=C,CH2)与甲烷反应机制研究

在CCSD(T)-REL//B2GP-PLYP水平下构建[Au(CH_2)]^+与甲烷反应的可靠反应势能面,分析了C—H键活化过程中的几何结构变化情况;对反应IRC路径上关键点进行自然键轨道(NBO)电荷和分子轨道分析,从理论上推定该氢转移过程属于氢负离子(H^-)转移.对[M—X]+(M=Au,Ag,Cu;X=C,CH_2)与甲烷反应进行对比,分析了甲烷作为氢供体反应过程的内在影响因素.M—X键能和反应活性中心C上直接参与反应的低能轨道对反应活性均起重要作用,两者协同调控微观反应机制.

D-和L-丙氨酸晶体的突现顺磁性:准一维N^+H…O^-氢键的自旋-轨道分离(英文)

研究了与磁场强度相关的手性丙氨酸晶体的电子轨道运动的磁性质.根据丙氨酸单晶的两性离子(+NH3-C(CH3)H-CO2-)模型的手性和蛋白质中肽键晶格结构的螺旋性,当外加磁场为5T,磁场方向平行于丙氨酸晶轴c(z)的极性N+H…O-氢键,观察到D-丙氨酸晶格中,氢原子的电子自旋翻转,在297.6K直接突现顺磁性.L-丙氨酸则先发生电子自旋转向,然后在303.9K突现顺磁性.实验发现:外加强磁场可以分裂手性丙氨酸晶格中氢键的简并顺磁态,并测出能差.本文进一步证明了准一维极性N+H…O-氢键在晶格中可以发生自旋-轨道分离,表现出一维物理的基本特征.

一个新型的通过氢键和π…π相互作用形成的三维 Ni(Ⅱ)聚合物[Ni(μ-isophthalate)(CH_3OH) _4]_n(英文)

合成了一个新型的镍 ( )配合物 [Ni(m-path) (CH3OH) 4]n(m-path)为间苯二酸 ) ,并通过 X-射线衍射测得其晶体结构 .晶体属单斜晶系 ,空间群为 C2 /c,晶胞参数 a=1 .693 1 (8) nm,b=1 .2 965 (6) nm,c=0 .73 40(3 ) nm,α=90°,β=1 0 9.3 83 (7)°,γ=76.763 (5 )°,V=1 .5 1 99(1 1 ) nm3,Z=4.相邻的一维之字链通过氢键和 π…