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1.
采用表面改性法制备了负载型Sn2(OMe)2Cl2/SiO2双核桥联配合物催化剂,用IR,TPD和微量反应技术研究了催化剂的表面结构、化学吸附性能和反应活性.结果表明,双核桥联配合物Sn2(OMe)2Cl2以O(Me)为桥,Cl为配体,并以Sn-O-Si形式键合到SiO2表面上;CO2与催化剂表面的金属离子Sn4+和桥基配体OMe的O2-形成桥式和甲氧碳酸酯基两种吸附态,CH3OH与催化剂表面的金属离子Sn4+仅形成一种分子吸附态;在413K以下,CO2和CH3OH在Sn2(OMe)2Cl2/SiO2催化剂表面上以近100%的选择性生成碳酸二甲酯;CO2在催化剂表面形成的甲氧碳酸酯基吸附态是生成DMC的关键物种,其与在同一活性中心的分子吸附态甲醇的反应决定了催化剂的活性和产物选择性.  相似文献   

2.
A new open-framework germanium oxide Ge(10)O(21)(OH).N(4)C(6)H(21) has been hydrothermally synthesized at 180 degrees C for 6 days by using the tris(2-aminoethyl)amine (tren) molecule as a structure-directing agent. This compound was characterized by means of single-crystal X-ray diffraction and FTIR. It crystallizes in the noncentric monoclinic system Cm (a = 14.0495(2) A, b = 12.8058(3) A, c = 9.2637(2) A, beta = 128.406(1) degrees, Z = 4). Its three-dimensional framework is built up from GeO(4) and GeO(3)(OH) tetrahedra connected by vertexes to GeO(5) trigonal bipyramids and GeO(6) octahedra. A pseudo-cubic building unit ("4-3" subunit) consists of four GeO(4) tetrahedra, two GeO(5) trigonal bipyramids, and one GeO(6) octahedron (Ge(7)). In the "4-3" block, the GeO(5) trigonal bipyramids share a common edge. This Ge(7) entity is linked to three tetrahedral units GeO(3)X (X = O, OH), and this forms an original decameric building unit Ge(10)O(21)(OH) which is new in the germanates crystal chemistry. It results in a relatively dense open framework composed of pear-shape cavities (7(8)6(2)5(2)4(4)3(2)) encapsulating the triprotonated tren molecule. The inorganic network contains small pores delimited by 7-ring channels running along [001].  相似文献   

3.
The reaction of [n-Bu(2)SnO](n) with 1,5-naphthalenedisulfonic acid tetrahydrate in a 1:1 stoichiometry followed by reaction with 2,2'-bipyridine-N,N'-dioxide (BPDO-I) afforded a 1D-coordination polymer [n-Bu(2)Sn(BPDO-I)(1,5-C(10)H(6)(SO(3))(2))](n) (1) where the disulfonate ligand acts as a bridging ligand between two tin centers. An analogous reaction involving [Ph(2)SnO](n) afforded a trihydrated O,O'-chelated diorganotin cation [{Ph(2)Sn(BPDO-I)(H(2)O)(3)}(2+)][C(10)H(6)(SO(3)(-))(2)]·2CH(3)OH (2·2CH(3)OH). Utilizing two equivalents of BPDO-I in this reaction resulted in the ionic complex [{Ph(2)Sn(BPDO-I)(2)(H(2)O)}(2+)][C(10)H(6)(SO(3)(-))(2)]·3H(2)O (3·3H(2)O). In 2 and 3 the sulfonate ligands are not present in the coordination sphere of tin. Reaction of [n-Bu(2)SnO](n) and 1,5-naphthalenedisulfonic acid tetrahydrate, followed by reaction with [bis(diphenylphosphoryl)methane (DPPOM)] resulted in the formation of, [{n-Bu(2)Sn(DPPOM)(2)(H(2)O)(1,5-C(10)H(6)(SO(3))(SO(3)(-))}]·H(2)O (4·H(2)O). Of the two coordinating groups present in DPPOM, only one P=O group is coordinated to the tin atom. The remaining P=O motif is free and is involved in intramolecular H-bonding with the tin-bound water molecule. Using [Ph(2)SnO](n) instead of [n-Bu(2)SnO](n) afforded the ionic complex [{Ph(2)Sn(DPPOM)(2)}(2+){1,5-C(10)H(6)(SO(3)(-))(2)}] (5) where the DPPOM functions as a chelating ligand. The reaction of [n-Bu(2)SnO](n) with 1,5-naphthalenedisulfonic acid tetrahydrate followed by addition of one equivalent of 8-hydroxyquinoline (8-HQ) in presence of triethylamine afforded the neutral dinuclear complex, [(H(2)O)(8-Q)n-Bu(2)Sn(μ-1,5-C(10)H(6)(SO(3))(2))n-Bu(2)Sn(8-Q)(H(2)O)] (6) where the two tin atoms are bridged by the disulfonate ligand. Compounds 1-6 are thermally stable as shown by their thermogravimetric analyses.  相似文献   

4.
A novel germanium phosphate with a chain-like framework constructed from GeO(4)N(2) octahedra and PO(4) tetrahedra, [NH(4)](2)[Ge(NH(3))(2)(PO(4))(2)]·0.38H(2)O, was first synthesized via in situ decomposition of urea from ionic eutectic mixtures comprising urea and quaternary ammonium salts.  相似文献   

5.
We report the preparation of luminescent oxide-embedded germanium nanocrystals (Ge-NC/GeO2) by the reductive thermal processing of polymers derived from phenyl trichlorogermane (PTG, C6H5GeCl3). Sol-gel processing of PTG yields air-stable polymers with a Ge:O ratio of 1:1.5, (C6H5GeO1.5)n, that thermally decompose to yield a germanium rich oxide (GRO) network. Thermal disproportionation of the GRO results in nucleation and initial growth of oxide-embedded Ge-NC, and subsequent reaction of the GeO2 matrix with the reducing atmosphere results in additional nanocrystal growth. This synthetic method affords quantitative yields of composite powders in large quantities and allows for Ge-NC size control through variations of the peak thermal processing temperature and reaction time. Freestanding germanium nanocrystals (FS-Ge-NC) are readily liberated from Ge-NC/GeO2 composite powders by straightfoward dissolution of the oxide matrix in warm water. Composites and FS-Ge-NC were characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), and photoluminescence (PL) spectroscopy.  相似文献   

6.
The reactions of the digermanium and ditin alkyne analogues Ar'MMAr' (M = Ge or Sn) with R2NO, (R2NO = Me2C(CH2)3CMe2NO or N2O), result in complete MM bond cleavage to afford the germylene :Ge(Ar')ONR2 or the germanium(II) or tin(II) hydroxides {M(Ar')(micro-OH)}2.  相似文献   

7.
The reaction of Cp(CO)2FeEMe2 (E  As, Sb, Bi) with Me3P, Et3P, Me2PhP and (MeO)3P leads to a CO/R3P exchange and formation of the chiral derivatives Cp(CO)(R3P)FeEMe2. Cp(CO)[(MeO)3P]FeEMe2 rearranges already at room temperature to Cp(CO)[(Me3E]FeP(O)(OMe)2 which is transformed by (MeO)3P to Cp(CO)[(MeO)3P]FeP(O)(OMe)2. The high nucleophilicity of the new organometallic Lewis bases is established by the easy conversion of Cp(CO)(Me3P)FeSbMe2 to [Cp(CO)(Me3P)Fe(SbMe3)]I with MeI, or to [Cp(CO)(Me3P)FeSbMe2Fe(CO)LCp]Hal (L  CO, Hal  Cl; L  Me3P, Hal  Br) with Cp(CO)LFe-Hal, respectively. The new compounds are characterized by spectroscopy and elementary analyses.  相似文献   

8.
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 T4— 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).  相似文献   

9.
The isomorphous compounds NH(4)[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (1), K[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (2), Li(3)O[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (3), and Ba[(UO(6))(2)(UO(2))(9)(GeO(4))(2)] (4) were synthesized by hydrothermal reaction at 220 °C. The structures were determined using single crystal X-ray diffraction and refined to R(1) = 0.0349 (1), 0.0232 (2), 0.0236 (3), 0.0267 (4). Each are trigonal, P(3)1c. 1: a = 10.2525(5), c = 17.3972(13), V = 1583.69(16) ?(3), Z = 2; 2: a = 10.226(4), c = 17.150(9), V = 1553.1(12) ?(3), Z = 2; 3: a = 10.2668(5), c = 17.0558(11), V = 1556.94(15) ?(3), Z = 2; 4: a = 10.2012(5), c = 17.1570(12), V = 1546.23(15) ?(3), Z = 2. There are three symmetrically independent U sites in each structure, two of which correspond to typical (UO(2))(2+) uranyl ions and the other of which is octahedrally coordinated by six O atoms. One of the uranyl ions donates a cation-cation interaction, and accepts a different cation-cation interaction. The linkages between the U-centered polyhedra result in a relatively dense three-dimensional framework. Ge and low-valence sites are located within cavities in the framework of U-polyhedra. Chemical, thermal, and spectroscopic characterizations are provided.  相似文献   

10.
Solutions of the complexes of hypervalent manganese, [Mn(III)(C(2)O(4))(3)](3)(-) (in oxalate buffers), [Mn(IV)(bigH)(3)](4+) (in biguanide buffers), and [(bipy)(2)Mn(III)(O)(2)Mn(IV)(bipy)(2)](3+) (in bipyridyl buffers) may be reduced by s(2) center reductants In(I), Sn(II), and Ge(II), yielding Mn(II) quantitatively. In all cases, rates are determined by the initial act of electron transfer, giving an s(1) transient (In(II), Sn(III), or Ge(III)); subsequent steps are rapid and kinetically silent. The In(I)-Mn(III) and Ge(II)-Mn(III) reactions are inhibited by added oxalate, whereas the Sn(II)-(Mn(III)Mn(IV)) reaction is strongly accelerated by Cl(-). The In(I)-Mn(IV) reaction is complicated by formation of a 1:1 addition compound In(I).Mn(IV). We find no evidence for two-unit steps in any of these systems.  相似文献   

11.
We report a simple and efficient method for replacing germanium atoms in deltahedral Ge(9)(4-) clusters with Sb or Bi. While reactions of Ge(9)(4-) with EPh(3) (E = Sb, Bi) at room temperature are known to produce mono- and disubstituted clusters [Ph(2)E-Ge(9)-Ge(9)-EPh(2)](4-) and [Ph(2)E-Ge(9)-EPh(2)](2-), respectively, at elevated temperatures or with sonication they result in exchange of Ge cluster atoms with Sb or Bi. Structurally characterized from such reactions are the novel "n-doped" deltahedral Zintl ions [(EGe(8))-(Ge(8)E)](4-), (Sb(2)Ge(7))(2-), and [(SbGe(8))-SbPh(2)](2-).  相似文献   

12.
Eichler JF  Just O  Rees WS 《Inorganic chemistry》2006,45(17):6706-6712
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.  相似文献   

13.
Synthesis and Structures of Bis(amino)germa and -stanna Chalcogenides The cyclic bis(amino)germylene 1 and the -stannylene 2 react with elemental S, Se and Te to yield oxydation products of the general formula Me2Si(NtBu)2MEl2M(NtBu)2SiMe2 (M = Ge, El = S ( 4 ), El = Se ( 5 ), El = Te ( 6 ); M = Sn, El = Se ( 9 ), El = Te ( 10 )). As may be deduced from X-ray structures ( 4, 5, 6, 9, 10 ) all compounds show similar central skeletons: the three spirocyclicly connected four-membered rings SiN2M (2x) and MEl2M are oriented in an orthogonal way to oneanother. The germanium and the tin atoms thus are in a distorted tetrahedral coordination while the chalcogen atoms only have two neighbours in acute angles. If 1 is allowed to react with trimethylamine-N-oxide, the oxygen is transferred to germanium and [Me2Si(NtBu)2GeO]3 ( 3 ) is formed. Contrarily to the other compounds 3 can be described as a trimer. There is a central almost planar Ge3O3 six-membered ring, the germanium atoms serving as spiro-cyclic centres to three GeN2Si four-membered rings (X-ray structure of 3 ). In the central four-membered rings of 4, 5, 6, 9 and 10 no transanular bonding between the chalcogen atoms have to be considered although these atoms have small distances to oneanother. The mean M-El distances have been found to be: Ge? O 1.762(5), Ge? S 2.226(3), Ge? Se 2.363(3), Ge? Te 2.592(5), Sn? Se 2.536(3), Sn? Te 2.741(3) Å.  相似文献   

14.
有关锗的石墨炉原子吸收光谱分析,文献报道较少,对锗的原子化机理,亦有不同的看法[1~3].本文基于右墨炉中锗原孚化行为的观察,对锗原子形成的过程进行了讨论,认为原子化过程中,并存着二种还原反应:GeO2(s)+C→GeO(g)+CO(g),GeO2(s)+CO→GeO(g)+CO2,而锗原子的形成是GeO(g)热分解的结果。  相似文献   

15.
Leong CL 《Talanta》1971,18(8):845-848
A ternary complex between germanium, Catechol Violet (CV) and cetyltrimethylanunoniuni bromide is proposed for the determination of germanium. The stoichiometric ratio Ge:CV is 1:2. Beer's law is obeyed from 0.1 to 1.0 ppm of Ge. The method is highly selective. Interference from Sn(IV), Fe(III), Bi(III), Cr(VI), Mo(VI), V(V) and Sb(III) in mg amounts is eliminated by extracting the germanium into carbon tetrachloride from 9M HC1 and then stripping into water before the photometric determination.  相似文献   

16.
The cyclostibane R(4)Sb(4)(1)(R = 2-(Me(2)NCH(2))C(6)H(4)) was synthesized by reduction of RSbCl(2) with Mg in THF or with Na in liquid NH(3). The reaction of 1 with [W(CO)(5)(THF)] gives the stibinidene complex RSb[W(CO)(5)](2)(2). RSbCl(2) and (RSbCl)(2)E [E = O (6), E = S (8)] react with KOH or Na(2)S in toluene/water to give the heterocycles (RSbE)(n)[E = O, n= 3 (3); E = S, n= 2 (4)]. The chalcogeno-bridged compounds of the type (RSbCl)(2)E [E = O (6), E = S (8)] were synthesized by reaction of RSbCl(2) with KOH or Na(2)S in toluene/water, but also by reaction of RSbCl(2) with the heterocycles (RSbE)(n). The compounds (RSbI)(2)O (7) and (RSbBr)(2)S (9) were prepared via halogen-exchange reactions between (RSbCl)(2)E and NaI (E = O) or KBr (E = S) or by reactions between RSbI(2) and KOH or RSbBr(2) and Na(2)S. The reaction of cyclo-(RSbS)(2) with W(CO)(5)(THF) in THF results in trapping of the cis isomer in cyclo-(RSbS)(2)[W(CO)(5)](5). The solution behaviour of the compounds was investigated by (1)H and (13)C NMR spectroscopy. The molecular structures of compounds 1-7 and 9 were determined by single-crystal X-ray diffraction.  相似文献   

17.
Experimental and computational studies were performed to understand the electronic structure of ternary perovskites (ASnO(3), A = Ca, Sr, Ba, Cd), pyrochlores (RE(2)Sn(2)O(7), RE = Y, La, Lu; Cd(2)Sb(2)O(7)), and defect pyrochlore oxides (Ag(2)Sb(2)O(6)) containing the main group ions Sn(4+) and Sb(5+). In all compounds, the lowest energy states in the conduction band arise primarily from the antibonding Sn/Sb 5s-O 2p interaction. In the alkaline-earth stannate perovskites (BaSnO(3), SrSnO(3), and CaSnO(3)) the conduction bandwidth decreases strongly in response to the octahedral tilting distortion triggered by the decreasing size of the alkaline-earth cation. This in turn leads to a corresponding increase in the band gap from 3.1 eV in BaSnO(3) to 4.4 eV in CaSnO(3). The band gap of CdSnO(3) is relatively small (3.0 eV) considering the large octahedral tilting distortion. The origin of this apparent anomaly is the mixing between the empty Cd 5s orbitals and the antibonding Sn 5s-O 2p states. This mixing leads to a widening of the conduction band and a corresponding decrease in the band gap. The participation of the normally inert A-site cation in the electronic structure near the Fermi level can be considered an inductive effect, as it utilizes substitution on the A-site to directly modify the electronic structure of the SnO(3)(2)(-) framework. While the pyrochlore structure is more complicated, the energy level and width of the lowest energy conduction band can be analyzed in a manner similar to that utilized on the perovskite structure. The Sn-O-Sn and Sb-O-Sb bonds are highly distorted from linear geometry in pyrochlore, leading to a relatively narrow conduction band and a wide band gap. In Cd(2)Sb(2)O(7) and Ag(2)Sb(2)O(6) the Cd(2+) and Ag(+) ions exhibit a strong inductive effect that widens the conduction band and lowers the band gap significantly, very similar to the effect observed in the perovskite form of CdSnO(3).  相似文献   

18.
Nanocrystalline mixtures of Sn(II) and Sn(IV) oxide powders, potential gas sensor materials, are synthesized via a simple precipitation route using SnCl(2) as the precursor. Materials are characterized by powder X-ray diffraction, thermogravimetric analysis, UV-visible diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy. The ratio of Sn(II)/Sn(IV) in powders precipitated at room temperature, as well as the identity of the primary Sn(II) product (SnO or Sn(6)O(4)(OH)(4)), can be varied by adjusting aging time and washing procedures. The identity of the initial Sn(II) product influences the subsequent phase composition and degree of disorder in the tetragonal SnO(2) phase obtained following sintering in air. Analysis of the DRS absorption edge and long-wavelength (Urbach) absorption tail is used to determine the SnO(2) optical band gap and extent of disorder. SnO(2) obtained by heating the SnO/SnO(2) mixture at 600 or 800 degrees C has a smaller optical band gap and a broader Urbach tail than the analogous sample obtained from heating Sn(6)O(4)(OH)(4), indicating a more disordered material.  相似文献   

19.
Sodium germanate glasses are well-studied materials in which, unlike silicates but analogous to borates, the major structural consequence of alkali addition is generally thought to involve a coordination number increase of the network-forming Ge cations. However, the nature of this change, in particular quantifying fractions of nonbridging oxygens and of five- and/or six-coordinated Ge, has remained unresolved. We present here high-resolution 17O results, including triple-quantum MAS NMR (3QMAS), on a series of crystalline model compounds that allow the definition of ranges of chemical shifts corresponding to oxygens bonded to various coordinations of Ge. These include quartz- and rutile-structured GeO2, Na4Ge9O20, Na2Ge4O9, and Na2GeO3 (germanium dioxide, sodium enneagermanate, sodium tetragermanate, and sodium metagermanate). 3QMAS spectra of Na-germanate glasses ranging from 0% to 27% Na2O clearly show the development of partially resolved peaks as alkali is added, corresponding to signals from nonbridging oxygens (in the highest Na glasses) and to oxygen bridging between one four-coordinated and one higher coordinated Ge. As in conventional models of this system, nonbridging oxygen contents are much lower than in corresponding silicates. Although we do not directly distinguish between five- and six-coordinated Ge, modeling of bridging oxygen populations and comparison with measured speciation suggest that substantial proportions of both species are likely to be present. High-field 23Na MAS NMR shows systematic decreases in mean Na-O bond distance and/or coordination number with increasing alkali content that can be compared with published results for high-temperature liquids. These results, as well as comparison of molar volumes of glasses and high-temperature liquids, suggest the possibility of significant temperature effects on liquid structure.  相似文献   

20.
Interaction of metallic salts (M = Hg, Sb, and Te) with bis(triorganotin)oxide, (R3Sn)2O, where (R = C6H5, p‐CH3C6H4, and cyclo‐C6H11) at room temperature proceeded with the simultaneous cleavage of the Sn C and Sn O bonds, invariably yielding R2SnO along with other products. Thus the treatment of HgX2 (X = Cl, CN, SCN) with (R3Sn)2O resulted in the formation of polymeric diorganotin oxide R2SnO along with R3SnX and RHgX derivatives. The reaction of SbCl3 with (R3Sn)2O was found to give R2SnO, R3SnCl, and RSbCl2, whereas interaction with SbCl5 provided R2SnO, R2SnCl2, and R2SbCl3. Treatment of TeCl4 with (R3Sn)2O provided R2SnO, R3SnCl, and RTeCl3 at room temperature. At reflux temperature, reaction of PhTeCl3 with (R3Sn)2O yielded R2SnO, R3SnCl, and mixed diorganotellurium dichloride, RPhTeCl2. The course of reaction indicated the instability of Sn O Sn system proceeding via a four‐centered mechanism, providing organometallic compounds in profitable yield. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:278–283, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20547  相似文献   

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