激光烧蚀硅酸盐的材料产生氧化硅氧化铝复合团簇

采用习飞行时间质谱技术,用308nm准分子激光烧蚀不同硅铝比的ZSM-5沸石,产生了氧化硅氧化铝复合团簇.在负离子通道测得含铝的新团簇系列[(SiO~2)~n~-~1(ALO~2)]^-和[(SiO~2)~nOAl]^-,讨论了这些系列的丰度分布和样品硅铝比之间的关系.由于AlO~2有较高电负性,激光烧蚀产生的团簇负离子系列[(SiO~2)~n~-~1(AlO~2)]^-具有以AlO~2为生长核心的生长机理。     

银金硫三元团簇的形成与光过程的硫金敏化

采用激光烧蚀银金硫混合物样品产生团簇离子,用飞行时间质谱仪检测的方法研究了银金硫三元团簇离子的形成。研究表明,银硫二元团簇、金硫二元团簇和银金硫三元团簇同时生成,主要系列有(Ag~2~n~+~1S~n~-~1)^+、(Ag~2~n~-~1S~n)^-、(Ag~2~nAuS~n)^+和(Ag~2~nAuS~n~+~1)^-。将其与感光乳剂中的金硫敏化中心相关联,指出正离子团簇和负离子团簇分别在曝光过程中起着光电子陷阱和正空穴陷阱的作用。     

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。     

Ag/Se二元团簇的形成以及Ag与Se团簇反应的研究

用飞行时间质谱仪研究了激光直接溅射Ag/Se混合样品产生的二元团簇以及团簇正离子的光解行为;并用串级溅射反应装置研究了Ag和Se正负离子产物.在直接溅射产生的Ag/Se二元团簇中,正离子主要系列是:[(Ag₂Se)_nAg⁺],[(Ag₂Se)_nAg₃⁺];负离子主要系列是:[(Ag₂Se)_nAgSe^-],[(Ag₂Se)_nAgSe₂^-],[(Ag₂Se)_nSe^-].团簇正离子的光解结果表明,同样条件下Ag/Se二元团簇正离子光解比率比Ag/S大.在Ag和Se样品串级溅射实验中,主要得到AgSe_n⁺(n=4～9)和AgSe_nSe^-(n=4～7)系列的产物,在AgSe_n⁺系列中,n=4,6时丰度较大.这表明串级溅射反应和直接溅射二元混合样品两种过程中成簇机理是不同的.     

银硫二元团簇形成与光过程的硫敏化

采用激光烧蚀法和串级飞行时间质谱仪研究了银硫二元团簇离子的形成(银硫比例影响,尺寸大小范围,激光功率作用及紫外光解等).工作表明,带正电荷的团簇存在着两种不同的形式[(Ag_2S)_n·Ag]~+和[(Ag_2S)_(n-1)·Ag_3]~+.指出[(Ag_2S)]~+,[(Ag_2S)·Ag]~+和[(Ag_2S)·Ag_3]~+及其同系物是硫敏化中心作为光自由电子陷阱最可能存在的形式.     

激光烧蚀Al+与乙醇团簇的反应研究

利用激光烧蚀-分子束法对Al等离子体与乙醇团簇的反应进行了研究.飞行时间质谱测得的主要反应产物有Al⁺(C₂H₅OH)_n (n=3～10)与H⁺(C₂H₅OH)_n (n=1～14)团簇正离子和(C₂H₅OH)_n(H₂O)OH^- (n=0～8)团簇负离子.实验发现,烧蚀产生的Al等离子体与脉冲分子束的不同位置反应,对团簇离子的类别、大小及强度分布均产生很大影响.Al等离子体与脉冲分子束的前段反应,主要产生金属-复合物团簇离子Al⁺(C₂H₅OH)_n,且信号较强;Al等离子体与脉冲分子束的中段及后段反应,主要产生质子化团簇离子H⁺(C₂H₅OH)_n和团簇负离子(C₂H₅OH)_n(H₂O)OH^-,同时还出现强度较小的其他水合团簇离子,如H⁺(H₂O)m(C₂H₅OH)_n (m=1～2)等.     

硅-硫二元团簇[(SiS2)nS]-(n=1～4)的结构和稳定性的量子化学研究

用密度泛函（DFT）方法（B3LYP／6－31＋G^*)研究了硅硫团簇[(SiS2)nS]^-(n=1-4)的可能几何构型,得到各稳定构型的电子结构,并 相应的振动频率,预测了稳定构型的振动光谱,由其稳定构型的比较可在理论上预测团簇的生长规律,并可初步预测团簇的形成机理。     

锰/磷、钛/磷二元团簇的激光溅射产生与光解

利用激光溅射法直接产生了锰/磷、钛/磷二元团簇正、负离子MxPy±(M=Mn、Ti),并用串级飞行时间质谱仪研究了团簇离子的组成与激光光解规律.实验表明钛与磷间成簇的能力强于锰与磷间成簇的能力,且MPy+(M=Ti、Mn)团簇离子系列表现出峰强度随所含磷原子数目的奇偶性变化,这可能与P4结构的特殊稳定性有关.激光光解实验表明,失去中性P2、P4的通道为主要光解通道.随着团簇离子的生长,锰/磷团簇正离子逐渐由富磷簇向富金属簇过渡,钛/磷则趋向于形成钛原子数目与磷原子数目接近相等的团簇正离子,而二者与磷形成的团簇负离子MxPy-(M=Mn、Ti)逐渐趋向于x≈y,随样品中磷含量增加,锰/磷易形成富磷簇,钛/磷的组成趋向不改变.     

锗分族元素二元团簇及其与Co形成的团簇离子

通过比较激光烧蚀E1/E2 (代表Ge/Sn， Ge/Pb和Sn/Pb) 和Co/E (E为Ge、Sn、Pb)混合样品形成的二元团簇负离子飞行时间质谱分布和谱峰的相对强度及形成的幻数团簇离子峰，发现E1/E2二元团簇离子中原子量大的锗分族元素在团簇离子中占主要组分，而原子量小的元素则少量掺杂，其组成和分布特点说明其结构和性质与纯E团簇离子相似，可能的结构为该类负离子团簇所有原子都在笼结构的骨架上；对于二元团簇离子GeSn9－、GePb9－和SnPb9－其结构可能是双帽反四棱柱构型，只是每个原子均为骨架的一部分.而对激光烧蚀过渡金属钴与锗分族元素的混合物的研究发现，反应形成了丰富的Co/E二元合金团簇负离子，分析发现该类簇离子为钴内包覆于E(锗分族元素)笼状结构.幻数离子CoGe10－、CoSn10－和CoPb10－可能具有双帽四角反棱柱结构，而CoPb12－可能具有二十面体构型，钴原子均为笼状结构的中心.     

Mn/Se,MnO2/Se和Mn/SeO2体系形成的团簇离子的质谱研究

用飞行时间质谱法研究了激光直接溅射Mn/Se混合样品产生的二元团簇、团簇的光解行为及溅射MnO₂/Se和Mn/SeO₂样品产生的团簇正负离子。在Mn-Se二元团簇中,(Muse)_n⁺是正离子的主要组分,[(Muse)nSe]^-是负离子的主要组分。当n<5时,(Muse)_n⁺的紫外光解有多种通道;n≥5时光解以剥落MuSe方式进行。激光直接溅射MnO₂/Se,Mn/SeO₂两种体系产生的正负离子极为相似,符合团簇的气相聚合生长机理。正离子中(Mno)_n⁺是主要组分,负离子中Se_n^-,(Se_nO)^-和(SéO₃)^-是主要组分。     

^29Si（^27Al）MAS NMR考察镧离子在LaDAlY型沸石中的作用

用~(29)Si(~(27)Al)MAS NMR和辅加乙酰丙酮(acac)处理样品的静态~(27)Al NMR研究了镧离子对脱铝Y型沸石(DAIY)骨架硅、铝和非骨架铝(EFAL)的影响.结果表明,~(29)Si MAS谱的化学位移及其形状不仅取决于连接[SiO_4]四面体的[AlO]-四面体数目,而且还与引入镧离子的量有关.镧离子的引入导致~(27)Al MAS谱的明显宽化和不对称形变.另外,还讨论了镧离子对非骨架铝的影响.     

Aluminum phosphinate and phosphates of salen ligands

A new dealkylation reaction between organophosphate esters and Salen aluminum bromide compounds has been used to prepare three new aluminum salen compounds salen((t)Bu)AlOP(O)Ph2 (1) (salen = N,N'-ethylenebis(3,5-di-tert-butylsalicylideneimine)), [(MeOH)Alsalen((t)Bu)[OMePO2(O)]Alsalen((t)Bu)[OMePO2(O)]Alsalen((t)Bu)]Br (2), and [salpen((t)Bu)AlO]2[(BuO)2PO]2 (3) (salpen = N,N'-propylenebis(3,5-di-tert-butylsalicylideneimine)). Compounds 1.MeOH, 2, and 3 were characterized by single-crystal X-ray diffraction. Compound 1 is the first example of a monomeric aluminum Schiff base phosphinate. Compound 2 is a cationic Salen aluminum phosphate, and compound 3 contains an aluminophosphate ring. This work is the first example of the intentional use of an aluminum-based dealkylation reaction to form new compounds.     

The selective preparation of an aluminum oxide and its isomeric C-H-activated hydroxide

An aluminum oxide [LAlO]2 (1) has been prepared by the oxidative addition of aluminum(I) monomer LAl (L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3) with molecular oxygen. The short Al-O bonds in Al2(mu-O)2 result in short Al...Al contacts and subsequent steric crowding of the Ar substituents from the two oriented L. 1 hydrolyzes to form [LAl(OH)]2(mu-O) (2). A C-H-activated aluminum hydroxide 4, an isomer of 1, however, is obtained by hydrolysis of the bulky aluminum amide 3 rather than by a conversion by high temperature treatment of 1. This indicates selective preparation of isomers 1 and 4.     

Homogeneous forced hydrolysis of aluminum through the thermal decomposition of urea

Homogeneous hydrolysis of aluminum by decomposition of urea in solution was achieved because the urea coordinates to the Al3+ in solution, forming [Al(H2O)5 (urea)]3+ and to a lesser extent [Al(H2O)4 (urea)2]3+. Upon hydrolysis more hydrolyzed monomeric species, [Al(H2O)5 (OH)]2+, [Al(H2O)4 (OH)2]+, [Al(H2O)4 (urea)(OH)]2+, and [Al(H2O)3 (urea)(OH)2]+, were formed, followed by trimeric species and the Al13 Keggin complex [AlO4Al12(OH)24(H2O)12]7+. The 27Al NMR spectra indicated the formation of other complexes in addition to the Al13 at the end of the hydrolysis reaction.     

C‐O Bond Cleavage of Diethyl Ether and Tetrahydrofurane by [(dpp‐BIAN)AlI(Et2O)] [dpp‐BIAN = 1,2‐bis[(2,6‐di‐iso‐propylphenyl)‐imino]acenaphthene]

At elevated temperatures, the aluminum complex [(dpp‐BIAN)AlI(Et₂O)] ( 1 ) splits the C‐O bonds of diethyl ether and tetrahydrofurane yielding the dimeric alkoxides [(dpp‐BIAN)AlOEt]₂ ( 2 ) and [(dpp‐BIAN)AlO(CH₂)₄I]₂ ( 3 ), respectively. Already at ambient temperatures, a cleavage of the C‐O bond of THF is to observe in the reaction of 1 with CpNa in THF as confirmed by the formation of [(dpp‐BIAN)AlO(CH₂)₄C₅H₅]₂ ( 4a ) and [(dpp‐BIAN)Al{O(CH₂)₄C₅H₅}(THF)] ( 4b ) in a molar ratio of 1:2. The reaction of 1 with t‐BuOK affords the monomeric alkoxide [(dpp‐BIAN)AlO‐t‐Bu(Et₂O)] ( 5 ). Compounds 2 , 3 , and 4a/b were characterized by elemental analyses and IR spectra. Additionally, the structures of 2 and 3 were determined by single crystal X‐ray diffraction.     

Condensation reaction through base assistance within (Ph2SiO)8[AlO(OH)]4

When the polycyclic alumosiloxane (Ph₂SiO)₈[AlO(OH)]₄, which may be isolated as the diethyl ether adduct (Ph₂SiO)₈[AlO(OH)]₄·4OEt₂, is allowed to react with the double N-methylpiperidine (nmp) adduct of monochloroalane, AlH₂Cl·2nmp (1) (crystal structure analysis), the polycycle (Ph₂SiO)₈[AlO(O)_0.5]₄·2nmp (2) is obtained. Compared to the starting material and apart from the coordinating bases, the compound formally has lost two water molecules. The structure of (Ph₂SiO)₈[AlO(O)_0.5]₄·2nmp (2) can be derived from (Ph₂SiO)₈[AlO(OH)]₄ by substituting the central Al₄(OH)₄ motif through an Al₄O₂ entity which consists of a central Al₂O₂ ring coordinated to two further aluminum atoms through almost trigonal planar oxygen atoms. Using tris(ethylene)diamine (ted) as base and reacting it with (Ph₂SiO)₈[Al(OH)]₄, we have been able to isolate and completely characterize an intermediate on the way to these formally condensed alumosiloxane polycycles like in (Ph₂SiO)₈[AlO(O)_0.5]₄·2nmp (2). It has the composition (Ph₂SiO)₈[AlO(O)_0.25]₄·(OH·ted)₂·(OH₂·ted) (3) and has, compared to the starting material, the same number of hydrogen, oxygen, aluminum and silicon atoms within the inner molecular framework. Nevertheless, its structure is very different: whereas half of the molecule is structurally similar to (Ph₂SiO)₈[AlO(OH)]₄, with OH-groups forming hydrogen bridges to the nitrogen atoms of ted and connecting two aluminum atoms, the other half contains a unique oxygen atom which is in an almost planar trigonal bonding mode to three aluminum atoms. Furthermore, this part of the molecule has an aluminum atom to which a water molecule is coordinated, one of the hydrogen atoms being involved in hydrogen bonding to a further tris(ethylene)diamine (ted). This structure gives some important insights in the possible mechanism of the “condensation reaction” within (Ph₂SiO)₈[AlO(OH)]₄.     

Reductions by titanium(II) as catalyzed by titanium(IV)

The cobalt(III) complexes, [(NH3)5CoBr]2+ and [(NH3)5CoI]2+ are reduced by Ti(II) solutions containing Ti(IV), generating nearly linear (zero-order) profiles that become curved only during the last few percent of reaction. Other Co(III)-Ti(II) systems exhibit the usual exponential traces with rates proportional to [Co(III)]. Observed kinetics of the biphasic catalyzed Ti(II)-Co(III)Br and Ti(II)-Co(III)I reactions support the reaction sequence: [Ti(II)(H20)n]2+ + [Ti(IV)F5]- (k1)<==>(k -1) [Ti(II)(H2O)(n-1)]2+ + [(H2O)Ti(IV)F5]-, [Ti(II)(H2O)(n-1)]2+ + Co(III) (k2)--> Ti(III) + Co(II) with rates determined mainly by the slow Ti(IV)-Ti(II) ligand exchange (k1 = 9 x 10(-3) M(-1) s(-1) at 22 degrees C). Computer simulations of the catalyzed Ti(II)-Co(III) reaction in perchlorate-triflate media yield relative rates for reduction by the proposed active [Ti(II)(H2O)(n-1)]2+ intermediate; k(Br)/k(I) = 8.     

Dialane with a Redox-Active Bis-amido Ligand: Unique Reactivity towards Alkynes

The treatment of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with one equivalent of AlCl(3) and three equivalents of sodium in toluene at 110?°C produced a stable dialane, (dpp-bian)Al?Al(dpp-bian) (1). The reaction of compound?1 with pyridine gave Lewis-acid-base adduct (dpp-bian)(Py)Al?Al(Py)(dpp-bian) (2). Acetylene and phenylacetylene reacted with compound 1 to give cycloaddition products [dpp-bian(R(1) R(2) )]Al?Al[(R(2) R(1) )dpp-bian] (3: R(1) =R(2) =CH; 4: R(1) =CH, R(2) =CPh). These addition reactions occur across Al-N-C moieties and result in the formation of new C?C and C?Al bonds. At elevated temperatures, compound 4 rearranges into complex 5, which consists of a radical-anionic dpp-bian ligand and two bridging alken-1,2-diyl moieties, (dpp-bian)Al(HCCPh)(2) Al(dpp-bian). This transformation is accompanied by cleavage of the dpp-bian-ligand-alkyne C?C bond, as well as of the Al?Al bond. In contrast to its analogous gallium complex, compound 1 is reactive towards internal alkynes. In the reaction of compound 1 with PhC?CMe, besides symmetrical addition product [dpp-bian(R(1) R(2) )]Al?Al[(R(2) R(1) )dpp-bian] (R(1) =CMe, R(2) =CPh; 6), monoadduct [dpp-bian(R(1) R(2) )]Al?Al(dpp-bian) (R(1) =CMe, R(2) =CPh; 7) was also isolated. Complexes 1-7 were characterized by IR, (1) H?NMR (1-4), and electronic absorption spectroscopy (3-5); the molecular structures of compounds 1-7 were determined by single-crystal X-ray diffraction.     

f-Element disiloxanediolates: novel Si-O-based inorganic heterocycles

The preparation and structural characterization of scandium and f-element complexes derived from the disiloxanediolate dianion, [(Ph2SiO)2O]2-, are reported. Reactions of in situ prepared Ln[N(SiMe3)2]3 (Ln = Eu, Sm, Gd) with (Ph2SiOH)2O in different stoichiometries afforded the lanthanide disiloxanediolates [Eu[[(Ph2SiO)2O]Li(Et2O)]3] (1), [[[(Ph2SiO)2O]Li(dme)]2SmCl(dme)] (2), and [[[((Ph2SiO)2O]Li(thf)2]2GdN(SiMe3)2] (3). In situ formed (Ph2SiOLi)2O reacted with anhydrous NdBr3 (molar ratio 3:1) to give polymeric [[Nd[(Ph2SiO)2O]3[mu-Li(thf)]2[mu2LiBrLi(thf)(Et2O)]]n] (4). Treatment of 3 with Ph2Si(OH)2 in the presence of acetonitrile yielded the dilithium trisiloxanediolate derivative [[Ph2Si(OSiPh2O)2][Li(MeCN)]2]2 (5), which according to an X-ray analysis displays an Li4O4 heterocubane structure. The trinuclear scandium complex [[[(Ph2SiO)2O]Sc(acac)2]2Sc(acac)] (6) was obtained by reaction of [(C5Me5)Sc(acac)2] (C5Me5 = eta5-pentamethylcyclopentadienyl) with (Ph2SiOH)2O in a 3:2 molar ratio. Selective formation of the colorless uranium(VI) derivative [U[Ph2Si(OSiPh20)2]2[(Ph2SiO)2O]] (7) was observed when uranocene, U(eta8-C8H8)2, was allowed to react with (Ph2SiOH)2O. An X-ray diffraction study of the solvated derivative [U[Ph2Si(OSiPh2O)2]2[(Ph2SiO)2O]].Et2O.TMEDA (TMEDA= N,N,N',N'-tetramethyl-ethylenediamine) (7a) revealed the presence of both the original [(Ph2SiO)2O]2- dianion as well as the ring-enlarged [Ph2Si(OSiPh2O)2]2- ligand in the same molecule.     

A new understanding of the co-catalytic activity of alumoxanes: The opening of a black box!

The isolation of non-fluxional alumoxane compounds, [(^tBu)₂Al{OAl(^tBu)₂}]₂ and [(^tBu)AlO]_n (n = 6, 7, 8, 9), has allowed for an investigation of the mode of activity observed for alumoxanes as co-catalysts for the zirconocene polymerization of olefins. [(^tBu)₂Al{OAl(^tBu)₂}]₂, which contains two three-coordinate aluminum centers, shows no reaction with Cp₂ZrMe₂, and no catalytic activity towards ethylene polymerization. In contrast, the closed cage compound [(^tBu)AlO]₆ reacts reversibly to give the ion pair complex, [Cp₂ZrMe][(^rBu)₆Al₆O₆Me], which is active as a catalyst for the polymerization of ethylene. Polymerization is also observed for mixtures of Cp₂ZrMe₂ with [(^tBu)AlO]_n (n = 7, 9). A new concept, “latent Lewis acidity”, is proposed to account for the reactivity of the cage alumoxanes, [(^tBu)AlO]_n.