Zur Kenntnis der inversen Perowskite M3TO (M = Ca,Sr, Yb; T = Si,Ge, Sn,Pb)

On the Inverse Perovskites M₃TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb) Ca₃SiO and seven further inverse perovskites M₃TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb) were prepared in iron crucibles under argon by the reactions 6 M + TO₂ + T = 2 M₃TO, and 3 M+ TO = M₃TO for Yb₃PbO, respectively, at temperatures between 1123 to 1173 K. The crystal structures of all compounds were solved and refined using X—ray powder diffraction methods. Ca₃SiO, Ca₃GeO, Sr₃SiO, Sr₃GeO, Yb₃SiO and Yb₃GeO are orthorhombic perovskites (anti—GdFeO₃—type, space group Pbnm, No. 62, Z = 4). They show slightly distorted corner—sharing OM₆ octahedra that are tilted with respect to their positions in the ideal perovskite structure. The effective radii of the T^4— vary significantly with M²⁺. Thus, these perovskites can no longer be discussed in terms of the hard—sphere model, and Goldschmidt's tolerance factor does not apply. The ideal cubic representatives Yb₃SnO and Yb₃PbO were refined in space group Pm3¯m (anti—SrTiO₃ type, Z = 1).     

Modellrechnungen von Kraftkonstanten der Tetramethyl-Verbindungen (CH3)4−nM(CD3) n,M=Si,Ge, Sn,Pb

Fromthe experiemntal fundamental vibrational frequencies of (CH₃)₄ M, (CD₃)₄ M and (CH₃)₃ MCD₃,M=Si, Ge, Sn, Pb, and of (CH₃)₂Si(CD₃)₂ and CH₃Si(CD₃)₃ a transferable local symmetry type force field for (CH₃)_4–n M groups has been calculated. Applications involving differentM atoms and numbersn of CH₃ groups are presented.

     

Reactions between M+ (M = Si,Ge, Sn and Pb) and benzene in the gas phase

Using a laser ablation/inert buffer gas ion source coupled with a reflectron time-of-flight mass spectrometer, the gas-phase reactions between the IVA group element ions M(+) (M = Si, Ge, Sn and Pb) and benzene seeded in argon gas were studied. In addition to the association reaction pathway (forming [M(C(6)H(6))(x)](+), x = 1, 2, etc.), benzene was dissociated to form complex ions [M(C(5)H(5))](+), [M(C(7)H(5))](+) and [M(C(9)H(x))](+) (x = 5, 7 and 9), etc. DFT theoretical calculations indicated that, in the association products [M(C(6)H(6))](+), the M atom is close to one carbon atom of benzene, while in most of the dissociation complexes, pentagonal structures (M/cyclopentadienyl derivatives) were formed, with the M atom situated near the fivefold axis of the five-membered ring. The bond patterns in these complexes are discussed.     

Synthesen mit verbindungen R3M-Hg-MR3 und (R2M-Hg)n(M = C,Si, Ge,Sn) : XI. Mercurierung und demercurierung mittels di-t-butylquecksilber, (CH3)3C-Hg-C(CH3)32

Me₃CHgCMe₃ (I) adds to strongly polar CC groups as well as to some CC and NN groups resp., forming t-BuHg containing cis-products. Its reactivity is higher than that of Et₂Hg and equals that of Me₃SiHgSiMe₃ to some extent. In most examples, polar four-center transition states are assumed, but radical reactions occur, too. In the Hg containing adducts investigated, the t-BuHg group can be replaced by the Me₃Sn group easily, by using Me₃SnH. Hg is split off, and i-C₄H₁₀ is evolved quantitatively.     

14族杂环戊二烯分子(硅、锗、锡)的电子结构与光谱性质

14族杂原子取代的杂环戊二烯分子具有独特的光谱性质, 成为发光材料的明星分子. 为了更深层次地理解硅、锗、锡杂环戊二烯分子的光谱性质, 本文从理论上计算了它们的电子结构及其吸收和发射光谱. 分别采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT), 优化了硅、锗、锡杂环戊二烯分子基态和第一激发态的平衡构型, 计算了电子结构和振动性质. 在此基础上, 运用振动关联函数公式计算了吸收光谱和发射光谱. 得到的吸收光谱和发射光谱, 特别是发射光谱的半峰宽与现有的实验值吻合很好. 通过分析结构和光谱性质的关系, 指出光谱的性质主要取决于苯环转动对应的低频振动模式和中心环C—C键的伸缩振动对应的高频振动模式.     

Bicyclo[2.2.2]octanes HC(SiMe2E)3MR (E=S, Se; M=Si, Ge, Sn; R=Me, Ph, Vi)

The reactions of 1:1 mixtures of the trisilylmethane HC(SiMe₂Cl)₃ (1b) and organo Group 14 trichlorides (RMCl₃, R=Me, Ph, vinyl (Vi); M=Si, Ge, Sn) with Li₂E (E=S, Se) in THF yielded the new bicyclo[2.2.2]octanes HC(SiMe₂E)₃MR (2a-6b). The products were identified by GC-MS and multinuclear NMR spectroscopy. Trends of the NMR data are discussed. The molecular structures of HC(SiMe₂S)₃SiMe (2a), HC(SiMe₂S)₃SiPh (3a), HC(SiMe₂Se)₃SiVi (4b) and HC(SiMe₂Se)₃GeMe (5b) are reported.     

Interaction between cobaltocenium and decamethylcobaltocenium salts and Ph3ELi (E = Si,Ge, Sn)

Reactions of cobaltocenium salts [(C₅R₅)₂Co]PF₆ (R = H, Me) with Ph3ELi (E = Si, Ge, Sn) and with Ph₂SbLi mainly follow two pathways (nucleophilic addition and one-electron reduction), yielding cobalt cyclopentadiene-cyclope ntadienyl complexes (⁴-Ph₃EC₅R₅)(⁵-C₅R₅)Co (R = H, E = Si, Ge, Sn; R = Me, E = Si) and cobaltocenes (C₅R₅)₂Co (R = H, Me), respectively. The contribution of nucleophilic addition of Ph₃ELi decreases in the order of elements Si > Ge > Sn and when hydrogen atoms are replaced by methyl groups in the initial cobaltocenium salt. Thermal decomposition of cobalt cyclopentadiene-cyclopentadienyl complexes results in substituted cobaltocenes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 10, pp. 2557–2560, October, 1996.     

Dipolmomente der Alkohole (CH3)3M(CH2)nOH (M=C,Si, Ge; n=1−4)

Ohne Zusammenfassung     

Synthesis and characterization of imidocubanes with exocube Ge(IV) and Sn(IV) substituents: [M(mu3-NGeMe3)]4 (M = Sn, Ge, Pb); [Sn(mu3-NSnMe3)]4

The heteroleptic lithium amide, [(Me3Sn)(Me3Ge)NLi.(Et2O)]2 (2), reacts with MCl(2) (M = Sn, Ge, Pb) to yield the corresponding cubane complexes [M(mu3-NGeMe3)]4 [M = Sn (3), Ge (4), Pb (5)]. In an analogous reaction with SnCl2, the lithium stannylamide, [(Me3Sn)2NLi.(Et2O)]2 (1), produces the mixed-valent Sn congener [Sn(mu3-NSnMe3)]4 (6). All imidocubanes contain both di- and tetravalent group 14 metals that are bridged by N. These structures are comprised of M4N4 (M = Sn, Pb, Ge) cores that possess varying distortion from perfect cube geometry. The Pb derivative (5) exhibits enhanced volatility and vapor-phase integrity.     

Spektroskopische Untersuchungen an XCH2(CH3)2SiF-Verbindungen

Mössbauer-spectrometric and Catalytic Investigations of the System Pt? Sn? η-Al₂O₃ Tin compounds on an Al₂O₃-carrier exhibit interactions with the carrier, their chemical properties are different from those of the carrier-free compounds. In reduced Pt? Sn? Al₂O₃ catalysts of different preparation there are different interactions between platinum and tin. Impregnation of the carrier with platinum-tin complexes gives vicinal locations of both compounds in socalled Pt? Sn ensembles. The modification of the electronic properties of a part of the platinum by tin in Pt? Sn? Al₂O₃ catalysts causes a decrease of the adsorption of hydrogen and of the activity in the dehydrogenation of cyclohexane, and an increase of the activity of dehydrocyclization of n-heptane.     

Pu3M和PuM3 (M=Ga,In, Sn,Ge)化合物的电子结构和形成热

采用全势线性缀加平面波(FPLAPW)方法, 在广义梯度近似(GGA)+自旋轨道耦合(SOC)+自旋极化(SP)下计算了具有AuCu3构型的Pu3M和PuM3 (M=Ga, In, Sn, Ge)化合物的平衡结构、电子结构和形成热. 计算的晶格常数与实验值符合得很好; 态密度分析表明Pu 和M 原子轨道间的杂化作用决定于Pu 6d-Pu 5f、Mp-Pu 6d和Msp-M sp轨道杂化之间的竞争, 而这种竞争又依赖于M的含量; 电负性差和电子杂化效应是影响Pu3M和PuM3化合物形成热和稳定性的两个重要因素, 电负性差越大, M的s、p带中心距费米能级越远, Pu3M(PuM3)化合物的形成热越负, 稳定性越高.     

Protolyses of (CH3)3SnM(CH3)3 (M = Sn,Ge, Si,C)

Product and kinetic studies on the reactions of hydrogen chloride in methanol solution with the substrates (CH₃)₃SnM(CH₃)₃ (M = Sn; Ge and Si) show that both SnM and SnCH₃ cleavage reactions occur, at similar rates, and are followed by other reactions giving complex but explicable mixtures of products. Similar behaviour is observed for trifluoroacetolysis in carbon tetrachloride solution, and some intermediates are observable. Trifluoroacetolysis of (CH₃)₃SnC(CH₃)₃ results in exclusive SnCH₃ cleavage. The very slow apparent solvolysis in acetic acid solution is thought to involve reaction with dissolved oxygen.     

C-H activation of cycloalkenes by dimetallynes (M = Ge, Sn) under ambient conditions

Treatment of the dimetallynes Ar'EEAr' [E = Ge, Sn; Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-iPr(2))(2)] with a cyclic olefin-cyclopentadiene (CpH), cyclopentene, 1,4-cyclohexadiene (CHD), or cyclohexene-showed that, with the exception of cyclohexene, they react readily, affording C-H activation at room temperature. Reaction of the digermyne and distannyne with CpH gave the cyclopentadienyl anion, which is bound in a π-fashion to a mononuclear group 14 element center, along with evolution of hydrogen gas. Unusually, the digermyne also reacted with cyclopentene to give the same dehydroaromatization product, formed from triple C-H activation/dehydrogenation. It also was found to react with CHD to give a mixture of (Ar'GeH)(2), benzene, and a new 7-germanorbornadiene species bound to a cyclohex-2-enyl fragment.     

Vibrational assignment of some X3MCo(CO)4 molecules (M = Si,Ge, Sn and X = Cl,Br, I)

The infrared and Raman vibrational spectra of X₃MCo(CO)₄ compounds (M = Si, Ge, Sn and X = Cl, Br, I) including depolarization measurements are presented. These spectra result in complete vibrational assignments which are different from those reported previously.     

Si(SiMe3)3]3Ge9M(CO)3(-) (M=Cr, Mo, W): coordination chemistry with metalloid clusters

Very recently it was shown that the metalloid cluster compound {Ge(9)[Si(SiMe(3))(3)](3)}(-)1 can be used for subsequent reactions as the shielding of the cluster core is rather incomplete. So the reaction of 1 with Cr(CO)(3)(CH(3)CN)(3) leads to a cluster enlargement where the chromium atom is incorporated into the cluster core. Here further applications of 1 as a flexible ligand in coordination chemistry are presented where the reaction of 1 with Mo(CO)(3)(EtCN)(3) and W(CO)(3)(CH(3)CN)(3) leads to [(CO)(3)MoGe(9)R(3)](-)4 and [(CO)(3)WGe(9)R(3)](-)5 respectively (R = Si(SiMe(3))(3)), showing that 1 can indeed be used as a flexible ligand in coordination chemistry. Structural and electronic properties of the Ge(9)M clusters 4 and 5 are discussed as well as mechanistic aspects of their formation.     

LCGTO MP LSD calculations for the diatomics PdX (X = C,Si, Ge,Sn)

Results are presented of a theoretical study of RhC, PdC, PdSi, PdGe and PdSn metal-alloy diatomics performed with the LCGTO MP LSD method. For the RhC molecule the computed electronic structure and spectroscpic constants are in good agreement with experimental data. The ground state of RhC is found to be ²Σ⁺ withe the lowest-lying excited state, ²II, at 10654 cm⁻¹ above the ground state, in good agreement with experiment and with ab initio CI calculations. For PdC and the other Pd-group IV A dimers the ground state is predicted to be ¹Σ and the two lowest-lying excited state are ³II (at 2718 cm⁻¹ for PdC) and ³gS (at 12164 cm⁻¹ for PdC). Our results are in disagreement with ab initio CI studies for PdC, which found a ³Σ ground state with a ³II lowest-lying excited state, and for PdGe, which found a ³II ground state followed by ³Σ⁻ and ¹Σ⁺.