银和硫团簇的反应

研究气相中原子或团簇的化学反应可以使我们从分子水平上研究化学反应的机理．激光溅射固体样品产生团簇,进而研究所形成团族的化学反应是研究团簇反应的一种方法．用高强度激光使固体样品气化,气化物彼此碰撞反应并在真空中膨胀冷却形成团簇和团簇离子,这一类反应是成...     

气相中原子分子成簇动力学Ⅰ.动力学的基本模型

提出了气相原子、分子碰撞形成团簇的动力学一般模型，认为具有特定组份单元的粒子经碰撞后可任意组合成团簇．各缔合速率常数随团簇的尺寸和结构特征而变化．团簇的热解离速率主要取决于断键数．因此裂解出小碎片的几率较大．将上述模型用动力学方程表示，可计算在不同时刻的团簇尺寸分布．最后分析了激光烧蚀、电弧放电等几种形成团簇方法的具体条件．     

气相中原子分子成簇动力学 I. 动力学的基本模型

提出了气相原子，分子碰撞形成团簇的动力学一般模型，认为具有特定组分份单元的粒子经碰撞后可任意组合成团簇，各缔合速率常数随团簇的尺寸和结构特征而变化，团簇的热解离速率主要取决于断键数，因此裂解出小碎片的几率较大，将上述模型用动力学方程表示，可计算在不同时刻的团簇尺寸分布，最后分析了激光烧蚀，电弧放电等几种形成团簇的方法的具体条件。     

氰化钾团簇的结构和形成机理研究

利用激光气化铁氰化钾或亚铁氰化钾并利用飞行时间质谱检测方法对氰化钾团簇的形成机理进行了研究，结果发现：团簇正离子可归属为［Ｋ（ＫＣＮ）＿ｎ］￣＋，ｎ＝０～３７，它们的幻数为ｎ＝４、１３、２２、３７；团族负离子可归属为［（ＫＣＮ）＿ｎＣＮ］￣－＝，ｎ＝０～１３，它们的幻数为ｎ＝４、１３。这些幻数与氯化钠等碱金属卤化物团簇体系完全一致。这表明：它们的团簇结构应该是相同的，即１×３×３（ｎ＝４）、３×３×３（ｎ＝１３）、３×３×５（ｎ＝２２）、３×５×５（ｎ＝３７）结构。因此氰化钾晶体的初期形成过程也应采取ＮａＣｌ型结构的增长途径。在激光气化产生的等离子体中，正、负离子与中性团簇的碰撞增长反应、正离子与负离子的复合反应以及团簇的亚稳态解离反应造成了团簇离子的不同丰度分布。氰化钾团簇中稳定立方体结构的产生决定了幻数的出现。     

铜氧团簇负离子的产生

自Smalley等利用激光蒸发／超声分子束载带（ix／un）法产生c。。问起，这种方法逐渐成为形成高质量气相团簇的常用实验手段，其中分子束载带的主要作用是缓冲气体通过提供三体碰撞稳定动力学激发的团簇并促进高质量团簇的形成．但0’Keef6门和Cre。Sy同的实验发现无需利用缓冲     

银硫团簇离子的形成与光解

银硫团簇离子的形成与光解于忠德，高振，张南，朱起鹤，孔繁敖（中国科学院化学研究所分子反应动力学国家重点实验室，北京１０００８０）本文首次报道用激光溅射方法产生了银硫团簇离子，并研究了部分团簇离子的紫外激光解离规律。由于银与铜都是具有满壳层ｄ电子结构的...     

气相[（SiO2）nX]^—团簇产生机理

利用ＸｅＣｌ准分子激光烧蚀多种硅氧多孔结构材料，在负离子通道测得丰富的「（ＳｉＯ２）ｎＸ」＾－负离子团簇，并讨论了多孔网结构和表面活性基团的分布对激光能量的吸收，传输及团簇产生的重要作用。     

铅、硫团簇的形成、反应与光解

用激光直接溅射和串级溅射两种方法产生铅／硫二元团簇,并用串级飞行时间质谱仪研究了二元团簇的组份及光解规律,用激光直接溅射铜＋硫混合样品时,组成为PbnSn-1 和PbnSn-的团簇丰度最大,是二元团簇的结构骨架和稳定组份,而用激光串级溅射铅样品和硫样品,通过铅团簇与硫团簇的反应,则可得到PbnSm (n=1-3,m=0-9)和PbnSm-(n=1-7,m=0-9)。这两种二元团簇的产生方法对应两种不同的团簇形成机理。     

新团簇形成的动力学研究

利用紧束缚模型,通过对不同初始条件下的碱金属团簇的碰撞研究,得到形成大分子团簇的可能性.结果表明,对同一种团簇,具有空间对称性的团簇间的碰撞更易形成大团簇,而平面结构的团簇碰撞则反之,并且空间结构的团簇碰撞形成的新团簇复合体更加稳定.另一方面,团簇碰撞过程是可逆的.     

吡啶团簇的飞秒光电离和从头计算研究

用飞秒激光电离飞行时间质谱研究了吡啶分子团簇在400 nm波长下的多光子光电离,实验观测到一系列的质子化和非质子化团簇离子.结果表明,质子转移也能发生在弱氢键结合的分子间.通过分析离子峰宽和离子信号强度随气源压力的变化,得到质子化团簇离子来源于大团簇离子的碎裂,而非质子化团簇离子是中性团簇直接电离的结果.从头计算结果表明,吡啶团簇是通过弱氢键C-H…N 结合在一起的,并且团簇离子离解倾向于生成质子化产物.     

Aqueous solution chemistry of [Mo3CuSe4]n+ (n = 4, 5) and [W3CuQ4]5+ (Q = S, Se) clusters

The triangular cluster [Mo3Se4(H2O)9]4+ reacts with Cu turnings to give a new heterometallic cuboidal cluster [Mo3CuSe4(H2O)10]4+(purple; UV/Vis lambda(epsilon): 352(3907), 509(2613)). The reaction of [Mo3Se4(H2O)9]4+ with CuCl afforded the 5+ cube [Mo3CuSe4(H2O)10]5+(red; UV/Vis lambda(epsilon): 356(5406), 500(3477)). In contrast, [W3Se4(H2O)9]4+ both with Cu and CuCl gives the 5+ cube, [W3CuSe4(H2O)10]5+(yellow-green; UV/Vis lambda(epsilon): 312(5327), 419(3256) and 628(680)). Cyclic voltammetry of [M3CuQ4(H2O)10]5+ in 2 M HCl (M = Mo, W; Q = S, Se) shows a reversible one-electron reduction wave for the Mo clusters, but no reduction occurs for the W clusters prior to H+ reduction. In HCl solutions, Cl is coordinated to the Cu site of the clusters, alongside some less extensive coordination to Mo and W, and for [W3(CuCl)S4(H2O)6Cl3]+, isolated as the supramolecular adduct with cucurbit[6]uril, [W3(CuCl)S4(H2O)6Cl3]2Cl2 x C36H36N24O12 x 12H2O, the crystal structure was determined (Cu-W 2.856(4) angstroms, W-W 2.7432(15) angstroms, Cu-Cl 2.167(13) angstroms).     

CuCl3]- and [CuCl4]2- hydrates in concentrated aqueous solution: a density functional theory and ab initio study

In this work, structures and thermodynamic properties of [CuCl(3)](-) and [CuCl(4)](2-) hydrates in aqueous solution were investigated using density functional theory and ab initio methods. Contact ion pair (CIP) and solvent-shared ion pair (SSIP) structures were both taken into account. Our calculations suggest that [CuCl(3)(H(2)O)(n)](-) clusters might favor a four-coordinated CIP structure with a water molecule coordinating with the copper atom in the equatorial position for n = 3 and 4 in aqueous solution, whereas the four-coordinated SSIP structure with one chloride atom dissociated becomes more stable as n increases to 5. For the [CuCl(4)](2-) cluster, the four-coordinated tetrahedron structure is more stable than the square-planar one, whereas for [CuCl(4)(H(2)O)(n)](2-) (n ≥ 1) clusters, it seems that four-coordinated SSIP structures are slightly more favorable than CIP structures. Our calculations suggest that Cu(2+) perhaps prefers a coordination number of 4 in CuCl(2) aqueous solution with high Cl(-) concentrations. In addition, natural bond orbital (NBO) calculations suggest that there is obvious charge transfer (CT) between copper and chloride atoms in [CuCl(x)](2-x) (x = 1-4) clusters. However, compared with that in the [CuCl(2)](0) cluster, the CT between the copper and chloride atoms in [CuCl(3)](-) and [CuCl(4)](2-) clusters becomes negligible as the number of attached redundant Cl(-) ions increases. This implies that the coordination ability of Cl(-) is greatly weakened for [CuCl(3)](-) and [CuCl(4)](2-) clusters. Electronic absorption spectra of these different hydrates were obtained using long-range-corrected time-dependent density functional theory. The calculated electronic transition bands of the four-coordinated CIP conformer of [CuCl(3)(H(2)O)(n)](-) for n = 3 and 4 are coincident with the absorption of [CuCl(3)](-)(aq) species (～284 and 384 nm) resolved from UV spectra obtained in CuCl(2) (ca. 10(-4) mol·kg(-1)) + LiCl (>10 mol·kg(-1)) solutions, whereas the calculated bands of [CuCl(3)(H(2)O)(n)](-) in their most stable configurations are not when n = 0 - 2 or n > 4, which means that the species [CuCl(3)](-)(aq) exists in those CuCl(2) aqueous solutions in which the water activity is neither too low nor too high. The calculated bands of [CuCl(4)(H(2)O)(n)](2-) clusters correspond to the absorption spectra (～270 and 370 nm) derived from UV measurements only when n = 0, which suggests that [CuCl(4)](2-)(aq) species probably exist in environments in which the water activity is quite low.     

Single photon ionization of hydrogen bonded clusters with a soft x-ray laser: (HCOOH)x and (HCOOH)y(H2O)z

Pure, neutral formic acid (HCOOH)n+1 clusters and mixed (HCOOH)(H2O) clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV using a very compact, capillary discharge, soft x-ray laser. During the ionization process, neutral clusters suffer little fragmentation because almost all excess energy above the vertical ionization energy is taken away by the photoelectron, leaving only a small part of the photon energy deposited into the (HCOOH)n+1+ cluster. The vertical ionization energy minus the adiabatic ionization energy is enough excess energy in the clusters to surmount the proton transfer energy barrier and induce the reaction (HCOOH)n+1+-->(HCOOH)nH+ +HCOO making the protonated (HCOOH)nH+ series dominant in all data obtained. The distribution of pure (HCOOH)nH+ clusters is dependent on experimental conditions. Under certain conditions, a magic number is found at n=5. Metastable dissociation rate constants of (HCOOH)nH+ are measured in the range (0.1-0.8)x10(4) s(-1) for cluster sizes 4相似文献   

Incorporating distinct metal clusters to construct diversity of 3D pillared-layer lanthanide-transition-metal frameworks

Three novel 3D pillared-layer heterometallic lanthanide-transition-metal (hetero-Ln-TM) compounds, namely, Ln2Cu7I6(ina)7(H2O)6.H2O [ina=isonicotinic acid; Ln=Ce (1), Sm (2)] and Er4(OH)4Cu5I4(ina)6(na)(2,5-pdc).0.3H2O (3; na=nicotinic acid, 2,5-pdc=2,5-pyridinedicarboxylic acid), have been obtained by incorporating different metal clusters as building blocks under hydrothermal conditions. Compounds 1 and 2 are isostructural and consist of two distinct building units of dimeric [Ln2(ina)6] cores and inorganic 2D [Cu8I7]nn+ layers based on the [Cu3I3] and [Cu4I3]+ clusters. Compound 3 is constructed from decanuclear [Cu10I8]2+ clusters and inorganic 1D [Er4(OH)4]n8n+ cluster chain-based layers, which represent the first example of a 3D hetero-Ln-TM constructed by the combination of two distinct types of metal cluster units of a 1D [Er4(OH)4]n8n+ cluster polymer and a transition-metal cluster. It is interesting that decarboxylation occurred in the ortho position and 2,5-pdc2- was partially transformed into na- under hydrothermal conditions. Compounds 1-3 represent good examples of using different metal cluster units to construct fascinating 3D hetero-Ln-TM frameworks.     

Structure and dissociation characteristics of metal chloride anion clusters containing redox-active metal ions studied by laser desorption and electrospray ionization mass spectrometry and ab initio calculations

Copper chloride anion clusters with both copper oxidation states can be made by laser desorption of CuCl(2) crystals. We have used this method to study the dissociation characteristics of such cluster ions. The stability and the structure of the observed complexes were probed by ab initio calculations. These calculations show that many of these complexes are bridged structures. Thus, for the Cu(2)Cl(4) dimer anion, formally [ClCu-Cl-CuCl(2)](-) , with putative mixed copper oxidation states, the two copper ions become equivalent through bridging. Such bridging does not occur when redox inactive metal ions are present as in [ClCu-Cl-CaCl(2)](-) . By observing the dissociation characteristics of a variety of metal chloride cluster anions produced from binary mixtures, the following Cl(-) affinity order is obtained: FeCl(3) > CuCl > CaCl(2) > FeCl(2) > AgCl ≈ CuCl(2) ≈ ZnCl(2) > LiCl. Ab initio calculations on the Cl(-) affinity of selected chlorides confirm this order as do Cl(-) affinity estimates from the experimentally known vertical electron detachment energies of the superhalogens CaCl(3)(-) and LiCl(2)(-) . An equimolar mixture of CuCl(2) and FeCl(3) produces an intense cluster ion, which, from (65)Cu labeling experiments, is best described as FeCl(4)(-)···Cu(+)···(-)Cl(4) Fe, a Cu(+) bound superhalogen FeCl(4)(-) dimer. The Cu(+) ion can be replaced by the redox inactive alkali cations and by Ag(+) but these metal ion bound FeCl(4)(-) dimers show an entirely different fragmentation behavior which is attributed to the absence of bridging. Electrospray ionization (ESI) of CuCl(2) produces an extended series of (CuCl(2))(n) Cl(-) anions (n = 1-11) and so in ESI very limited reduction of Cu(2+) takes place. The (CuCl(2))(n) Cl(-) anions show an abundant dissociation via loss of neutral Cu(2)Cl(4) which according to our ab initio calculations is 9 kcal/mol more stable than two CuCl(2).     

Single photon ionization of van der Waals clusters with a soft x-ray laser: (SO2)n and (SO2)n(H2O)m

van der Waals cluster (SO2)n is investigated by using single photon ionization of a 26.5 eV soft x-ray laser. During the ionization process, neutral clusters suffer a small fragmentation because almost all energy is taken away by the photoelectron and a small part of the photon energy is deposited into the (SO2)n cluster. The distribution of (SO2)n clusters decreases roughly exponentially with increasing cluster size. The photoionization dissociation fraction of I[(SO2)(n-1)SO+] / I[(SO2)n+] decreases with increasing cluster size due to the formation of cluster. The metastable dissociation rate constants of (SO2)n+ are measured in the range of (0.6-1.5) x 10(4) s(-1) for cluster sizes 5< or =n< or =16. Mixed SO2-H2O clusters are studied at different experimental conditions. At the condition of high SO2 concentration (20% SO2 partial pressure), (SO2)n+ cluster ions dominate the mass spectrum, and the unprotonated mixed cluster ions (SO2)nH2O+ (1< or =n< or =5) are observed. At the condition of low SO2 concentration (5% SO2 partial pressure) (H2O)nH+ cluster ions are the dominant signals, and protonated cluster ions (SO2)(H2O)nH+ are observed. The mixed clusters, containing only one SO2 or H2O molecule, SO2(H2O)nH+ and (SO2)nH2O+ are observed, respectively.     

Mid-infrared characterization of the NH4 +(H2O)n clusters in the neighborhood of the n=20 "magic" number

Vibrational predissociation spectra are reported for size-selected NH4+ (H2O)n clusters (n=5-22) in the 2500-3900 cm(-1) region. We concentrate on the sharp free OH stretching bands to deduce the local H-bonding configurations of water molecules on the cluster surface. As in the spectra of the protonated water clusters, the free OH bands in NH4+ (H2O)n evolve from a quartet at small sizes (n<7), to a doublet around n=9, and then to a single peak at the n=20 magic number cluster, before the doublet re-emerges at larger sizes. This spectral simplification at the magic number cluster mirrors that found earlier in the H+(H2O)n clusters. We characterize the likely structures at play for the n=19 and 20 clusters with electronic structure calculations. The most stable form of the n=20 cluster is predicted to have a surface-solvated NH4+ ion that lies considerably lower in energy than isomers with the NH4+ in the interior.     

Single photon ionization of van der Waals clusters with a soft x-ray laser: (CO2)n and (CO2)n(H2O)m

Pure neutral (CO2)n clusters and mixed (CO2)n(H2O)m clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV. The distribution of pure (CO2)n clusters decreases roughly exponentially with increasing cluster size. During the ionization process, neutral clusters suffer little fragmentation because almost all excess cluster energy above the vertical ionization energy is taken away by the photoelectron and only a small part of the photon energy is deposited into the (CO2)n cluster. Metastable dissociation rate constants of (CO2)n+ are measured in the range of (0.2-1.5) x 10(4) s(-1) for cluster sizes of 5< or =n< or =16. Mixed CO2-H2O clusters are studied under different generation conditions (5% and 20% CO2 partial pressures and high and low expansion pressures). At high CO2 concentration, predominant signals in the mass spectrum are the (CO2)n+ cluster ions. The unprotonated cluster ion series (CO2)nH2O+ and (CO2)n(H2O)2+ are also observed under these conditions. At low CO2 concentration, protonated cluster ions (H2O)nH+ are the dominant signals, and the protonated CO2(H2O)nH+ and unprotonated (H2O)n+ and (CO2)(H2O)n+ cluster ion series are also observed. The mechanisms and dynamics of the formation of these neutral and ionic clusters are discussed.     

Electrospray ionization tandem mass spectrometric study of salt cluster ions: part 2--salts of polyatomic acid groups and of multivalent metals

Salt cluster ions formed from 0.05 M solutions of CaCl(2), CuCl(2) and Na(A)B (where A = 1 or 2 and B = CO(3)(2-), HCO(3)(-), H(2)PO(4)(-) and HPO(4)(2-)) were studied by electrospray ionization tandem mass spectrometry. The effects on salt cluster ions of droplet pH and of redox reactions induced by electrospray provide information on the electrospray process. CaCl(2) solution yielded salt cluster ions of the form (CaCl(2))(n)(CaCl)(x)(x+) and (CaCl(2))(n)(Cl)(y)(y-), where x, y = 1-3, in positive- and negative-ion modes, respectively. Upon collision induced dissociation (CID), singly charged CaCl(2) cluster ions fragmented, doubly charged cluster ions generated either singly or both singly and doubly charged fragment ions, depending on the cluster mass, and triply charged clusters fragmented predominantly by the loss of charged species. CuCl(2) solution yielded nine series of cluster ions of the form (CuCl(2))(n)(CuCl)(m) plus Cu(+), CuCl(+), or Cl(-). CuCl, the reductive product of CuCl(2), was observed as a neutral component of positively and negatively charged cluster ions. Free electrons were formed in a visible discharge that bridged the gap between the electrospray capillary and the sampling cone brought about the reduction of Cu(2+) to Cu(+). Upon CID, these cluster ions fragmented to lose CuCl(2), CuCl, Cl, and Cl(2). Na(2)CO(3) and NaHCO(3) solutions yielded cluster ions of the form (Na(2)CO(3))(n) plus Na(+) or NaCO(3)(-). Small numbers of NaHCO(3) molecules were found in some cluster ions obtained with the NaHCO(3) solution. For both Na(2)HPO(4) and NaH(2)PO(4) solutions, ions of the form (Na(2)HPO(4))(h), (NaH(2)PO(4))(i), (Na(3)PO(4))(j), (NaPO(3))(k) plus Na(+), PO(3)(-) or H(2)PO(4)(-) were observed. In addition, ions having one or two phosphoric acid (H(3)PO(4)) molecules were observed from the NaH(2)PO(4) solution while ions containing one sodium hydroxide (NaOH) molecule were observed from the Na(2)HPO(4) solution. The cluster ions observed from these four salts of polyatomic acid groups indicate that changes in pH occur in both directions during the electrospray process principally by solvent evaporation; the pH value of the acidic solution became lower and that of the basic solution higher.     

一种腙水解合成醛(酮)的绿色化学方法

腙与二水合氯化铜在80%乙腈溶液中回流反应1 h～3 h,高收率地制得相应的醛(酮)。实现了铜盐的循环使用,符合绿色化学理念。