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1.
Various 2-substituted 1,3-dithianes have been oxidized to the corresponding 1-oxides by cumene hydroperoxide in presence of a titanium complex (Ti(O-i-Pr) 4/(+)-DET/H 2O = 1/2/1) used in stoichiometric or lesser amounts. Enantioselectivity of up to 80% and excellent diastereoselectivity were achieved by a careful control of experimental conditions. The reaction temperature was found to be an important parameter. The relative stereochemistries of the new substituted monosulfoxides were determined by NMR spectroscopy. 相似文献
2.
Chiral allyltitaniums having an amino substituent at the C-4 position are prepared from optically active allylic alcohol derivatives 1 and a Ti(O-i-Pr) 4/2 i-PrMgCl reagent, which, in turn, react with aldehydes regio- and stereoselectively to afford 3-amino-2-vinylalkanols in excellent yields. 相似文献
3.
Reaction of the incompletely condensed silsesquioxane derivative Cy 7Si 7O 9(OH) 3 (1) with Ti(OEt) 4 affords the dimeric titanasilsesquioxane [(Cy 7Si 7O 12)Ti(μ-OEt)(EtOH)] 2 (13) in 81% yield. The known titanasilsesquioxane [Cy 7Si 7O 11(OSiMe 3)] 2Ti (18) has been prepared through a modified procedure starting from titanium tetraalkoxides. Novel oxotitanium silsesquioxane derivatives are obtained from reactions of titanocene dihalides with Cy 7Si 7O 9(OH) 2(OSiMe 3) (14). Cp 2TiCl 2 yields dinuclear (μ-O)[{Cy 7Si 7O 11(OSiMe 3)}TiCp] 2 (19), while with Cp *2TiCl 2 the trinuclear titanacycle Cp *2Ti 3O 3[Cy 7Si 7O 11(OSiMe 3)] 2 (20) is obtained. In addition, a new synthetic route to model compounds for titanium catalysts immobilized on silica has been developed. Disilylated Cy 7Si 7O 9(OH)(OSiMe 3) 2 (15) cleanly reacts with the ‘tucked-in’ fulvene complex Cp*Ti(C 5Me 4CH 2) to give the titanium(III) silsesquioxane Cp* 2Ti[Cy 7Si 7O 10(OSiMe 3) 2] (21). In a similar manner treatment of Cp*Ti(C 5Me 4CH 2) with Cy 7Si 7O 9(OH) 2(OSiMe 3) (14) affords the mono(pentamethylcyclopentadienyl) complex Cp*Ti[Cy 7Si 7O 11(OSiMe 3)][Cy 7Si 7O 10-(OH)(OSiMe 3)] (22) which is an advanced model compound for a catalytically active titanium center on a silica surface. The molecular structures of these titanium silsesquioxane derivatives have been determined by X-ray diffraction analyses. 相似文献
4.
Enantioselective catalytic trimethylsilylcyanations of aldehydes with 48% to 92% e.e. have been studied using the novel Ti-chiral Schiff base complexes. We have found that the catalyst led to high enantoselectivity when the molar ratio of the Schiff base 1 to Ti(O-i-Pr) 4 was 2:1. 相似文献
5.
Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C 5H 5)CH 2(2-C 4H 3NH) (2) with Ti(NMe 2) 4 affords bis(dimethylamido)titanium complex [(η 5-C 5H 4)CH 2(2-C 4H 3N)]Ti(NMe 2) 2 (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH 2(2-C 4H 3NH)} 2C 5H 4 (4), undergoes an analogous reaction with Ti(NMe 2) 4 to give [1,3-{CH 2(2-C 4H 3N)} 2(η 5-C 5H 3)]Ti(NMe 2) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies. 相似文献
6.
The X-ray diffraction study of crystals isolated from solutions obtained by reaction of Ba(OMe) 2 with Ti(OMe) 4 (molar ratio 1:2) in methyl alcohol was carried out; the crystals of the methanol solvate of the double barium-titanium methoxide, [Ba 2Ti 4O(OMe) 18(MeOH) 7]·MeOH (1), contain two Ba 2+ cations with different environments and two kinds of anionic binuclear titanium complexes with and without oxo-ligand, and thus can be formulated as [Ba(MeOH) 2] 2+[Ba(MeOH) 5] 2+[Ti 2O(OMe) 8] 2−[Ti 2(OMe) 10] 2−·MeOH. 相似文献
7.
文献报道了双(环戊二烯基)二硫氰基钛、锆、铪 [1-3]及双(甲基环戊二烯基)二硫氰基钛 [4]的合成。我们利用双(烷基环戊二烯基)二氯化钛、锆、铪与过量硫氰酸钾反应,合成了一系列新的双(烷基环戊二烯基)二硫氰基钛、锆、铪(见表1)。 相似文献
8.
As main composition of mishmetals, the four pure light lanthanide elements La, Ce,Pr or Nd was used individually instead of Ml or Mm as RE in preparation of AB 5 typed hydrogen storage alloy RE(Ni,Co,Mn,Ti) 5. The four alloys, La(Ni,Co 5Mn,Ti) 5, Ce(Ni,Co>ln,Ti) 5, Pr(Ni,Co,Mn,Ti) 5 and Nd(Ni,Co,Mn,Ti) 5 were then tested, characterized and compared in the their cell volumes (V cell), P-C-T curves, and mainly electrochemical characteristics against charge/discharge cycles, including the activation cycle number (n a),the maximum discharge opacity at 50 mA/g charge/discharge rate (C 50,max), the high-rate-dischargeability and the rate of decay (-dC/dn). These properties are compared and analyzed to reveal the difference of the effects of each element on the electrochemical properties of rare earth based AB 5 typed hydrogen storage alloy. 相似文献
9.
The reaction of norbornene (NBE) and norbornadiene (NBD) in the presence of seven-coordinate tungsten(II) and molybdenum(II) complexes of the [(CO) 4M(μ-Cl) 3M(SnCl 3)(CO) 3] and [MCl(M′Cl 3)(CO) 3(NCMe) 2] (M=W, Mo; M′=Sn, Ge) types leads to ring-opening metathesis polymerization (ROMP) and to the formation of high molecular weight polymers. The geometric structure of these polymers was determined by means of 1H- and 13C-NMR spectroscopy. The monitoring of the reaction between cyclic olefins and the metal complex by means of 1H-NMR spectroscopy allowed us to observe the coordination of NBD to metal atoms in the initiation step of the polymerization process. Compounds of the [MCl(SnCl 3)(CO) 3(η 4-NBD)] type prepared directly from [(CO) 4M(μ-Cl) 3M(SnCl 3)(CO) 3] or [MCl(M′Cl 3)(CO) 3(NCMe) 2] (M=W, Mo) in the presence of an excess of NBD initiate the ROMP reaction immediately. The detection of the first-formed products in the reaction between the metal complex and cyclic olefins provides valuable information concerning the nature of the initiating species. 相似文献
10.
A series of chromium(III) complexes [Cr(bipy)(HC 2O 4) 2]Cl·3H 2O (1), [Cr(phen)(HC 2O 4) 2]Cl·3H 2O (2), [Cr(phen) 2(C 2O 4)]ClO 4 (3), [Cr 2(bipy) 4(C 2O 4)](SO 4)·(bipy) 0.5·H 2O (4) and [Mn(phen) 2(H 2O) 2] 2[Cr(phen)(C 2O 4) 2] 3ClO 4·14H 2O (5) were synthesized (bipy=4,4′-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3–5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1–3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed. 相似文献
11.
The synthesis and reactivity of {(η 5-C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2} MCl 2 (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) with equimolar amounts of MCl 2 (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) and [Fe(dipy) 2]Cl 2 (5a) or [Fe(phen) 2]Cl 2 (5b). 1/ n[Cu IHal] n (6) or 1/ n[Ag IHal] n (7) (Hal = Cl, Br) react with {(η 5 -C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2}FeCl 2 (3a), by replacement of the FeCl 2 building block in 3a, to yield the compounds {(η 5-C 5H 4SiMe 3) 2Ti(C CSiMe 3) 2}Cu IHal (8) or {(η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2}Ag IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me 3SiCC-units is η 2-coordinated to monomeric Cu I Hal or Ag IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η 5-C 5H 4SiMe 3) 2 Ti(CSiMe 3) 2 (1) with 1/ n[Cu IHal] n (6) or 1/ n [Ag IHal] n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, 1H-NMR, MS). The magnetic moments of compounds 3 were measured. 相似文献
12.
我们曾经报道了腺嘌呤核苷3′,5′-环磷酸酯和3′,5′-环磷酰胺对肿瘤细胞的DNA和RNA的合成有明显的抑制作用 [1]。研究这类化合物对进一步了解c-AMP在生物系统中的作用机制以及它们与蛋白激酶和磷酸二酯酶的作用情况有一定价值 [2]。因此在合成一系列腺嘌呤核苷3′,5′-环磷酸酯和3′,5′-环磷酰胺的基础上 [1~3],我们用2′-保护核苷与三价磷试剂反应,经过一步环磷酰化反应合成了核苷3′,5′-环亚磷酸衍生物,后者经氧化和脱保护即可得到核苷3′,5′-环磷酸衍生物。本文将报道核苷环磷酰化反应中的立体化学问题。 相似文献
13.
A kinetic study of the oxidative addition of RC 6H 4CN (R = H, m-CN, p-CN) to Ni(DEPB) 2 (DEPB = 1,4-bis(diethylphosphino)butane) suggests a template mechanism leading to the fission of one C---CN bond. The reaction products are trans-planar cyano-organonickel(II) complexes, Ni 2(μ-DEPB) 2(RC 6H 4) 2(CN) 2 and Ni(η 1- DEPB)(RC 6H 4)(CN), in equilibrium. through exchange of DEPB. 相似文献
14.
The reaction of bis(pyrazol-1-yl)methane tetracarbonylmolybdenum(0) or tungsten(0) complexes with RSnCl 3 (R=Ph, Cl) at room temperature yielded heterobimetallic complexes CH 2(Pz) 2M(CO) 3(Cl)(SnCl 2R) (Pz represents substituted pyrazole; M=Mo or W; R=Ph or Cl) in good yields, which have been characterized by elemental analysis, 1H NMR and IR spectroscopy. The reaction of bis(3,5-dimethyl-4-halopyrazol-1-yl)methane tetracarbonyl tungsten with PhSnCl 3 did not take place even in refluxing CH 2Cl 2. The electronic and steric characteristics of substituents on the pyrazole ring remarkably influence the structures of the products. The structures of CH 2(3,5-Me 2-4-BrPz) 2W(CO) 3(Cl)(SnCl 3) (8) and CH 2(4-BrPz) 2Mo(CO) 3(μ-Cl)(SnCl 2Ph) (17) (Pz: pyrazole) determined by X-ray crystallography show that no chlorine-bridged W---Sn bond is observed in complex 8, while one chlorine-bridged Mo---Sn bond exists in complex 17. The Sn---M bond length is 2.7438(5) Å in complex 8 (W---Sn) and 2.7559(4) Å in complex 17 (Mo---Sn). 相似文献
15.
The H 2O 2-based epoxidation of bridged cyclic alkenes in a monophasic system containing low concentrations (<2 mM) of [Bu 4nN] 4[Pr 2iNH 3] 2H[P{Ti(O 2)} 2W 10O 38]·H 2O (1) (with two η 2-peroxotitanium sites in the anion) has been studied in search of the catalytically active species involved. 31P NMR spectra of 1, measured under a variety of conditions, revealed that the active species was not hydroperoxotitanium complex [P{Ti(OOH)} 2W 10O 38] 7−or [P{Ti(OOH)}Ti(O 2)W 10O 38] 7−. The reaction pathways for the alkene epoxidation are discussed to understand the kinetics (especially the initial [H 2O 2] dependence). It was concluded that the net catalytic reaction for the epoxidation occurred through the two-electron oxidation at the hydroperoxotitanium site in the catalyst. 相似文献
16.
The coordinatively unsaturated uranium(IV) complex U[N(C 6H 5) 2] 4 has been prepared via the stoichiometric reaction of diphenylamine with [(Me 3Si) 2N] 2
H 2. U[N(C 6H 5) 2] 4 coordinates Lewis bases such as Et 2O, THF, pyridine or (EtO) 3PO, based on electronic absorption spectroscopy and 1H NMR studies. Exchange between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4(L), where L is THF or pyridine, is rapid on the NMR time-scale between 307 and 323 K. Measurement of equilibrium constants for L = THF provides Δ H and Δ S values of −60 kJ mol −1 and −1.8 × 10 2 J K −1 mol −1, respectively. U[N(C 6H 5) 2] 4 coordinates and binds (EtO) 3PO much more tightly ( Keq = & > 10 4 M −1) than THF or pyridine with the exchange rate between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4[OP(OEt) 3] being close to the NMR time-scale. 相似文献
17.
From the reaction of MeReO 3 with the neutral arylamine C 6H 5CH 2NMe 2 and the aryldiamine C 6H 4(CH 2NMe 2) 2−1,3, have been isolated in good yields the 1/1 adduct complex [MeReO 3 · C 6H 5CH 2NMe 2], 1, and the 2/1 adduct complex [(MeReO 3) 2 · C 6H 4(CH 2NMe 2) 2− 1,3], 2, respectively. The X-ray molecular structure of 2 shows that both rhenium centres have a trigonal bipyramidal geometry and in the axial positions of each rhenium centre are one of the NMe 2 units of the aryldiamine ligand and a methyl group. The mono(ortho)-chelated arylaminorhenium trioxide complex [ReO 3(C 6H 4CH 2NMe 2−2], 3, can be synthesized by a transmetallation reaction of ClReO 3 with [ZnC 6H 4CH 2NMe 2−2 2] in a 2:1 molar ratio. In a similar way the bis(ortho)-chelated arylaminorhenium trioxide complex [ReO 3C 6H 3(CH 2NMe 2) 2−2,6], 4, can be synthesized by addition of a mixture of [Li 2C 6H 3(CH 2NMe 2) 2−2,6 2] and ZnCl 2 to ClReO 3. Complexes 3 and 4 have been isolated as white solids in 66% and 81% yields respectively. The rhenium centre in complex 4 has a bicapped tetrahedral geometry in which the monoanionic C 6H 3(CH 2NMe 2) 2−2,6 − ligand is pseudo-facially bonded with a characteristic N1-Re-N2 angle of 107.7(3)°, a Re-C ipso bond length of 2.112(11) Å and Re-N1 and Re-N2 bond lengths of 2.518(9) Å and 2.480(8) Å respectively. 相似文献
18.
Treatment of ruthenium complexes [CpRu(AN) 3][PF 6] (1a) (AN=acetonitrile) with iron complexes CpFe(CO) 2X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe 3, PMe 2Ph, PMePh 2, PPh 3, P(OPh) 3; X=Cl, Br, I) in refluxing CH 2Cl 2 for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO) 2X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe 3, PMe 2Ph, PMePh 2, PPh 3, P(OPh) 3; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN) 2][PF 6] (1b: L=CO, 1c: P(OMe) 3) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)] 2 was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH 2Cl 2 at room temperature to give 3a, and transforms into 7a by the reaction with PMe 3. 相似文献
19.
The gallium(I)tris(trimethylsilyl)silyl compound {GaSi(SiMe 3) 3} 4 (1) is obtained by reaction of Ga 2Cl 4-2dioxane with LiSi(SiMe 3) 3-3THF. The crystal structure of 1 reveals a tetramer with a nearly regular tetrahedral framework of gallium atoms. The gallium-gallium distances average 258.4 pm. Ab initio calculations on various substituted gallium tetrahedrons showed a greater stability of silyl-substituted cages compared with organyl substituted ones. Crystal data, with Mo K radiation are as follows: {GaSi(SiMe 3) 3} 4 · Si(SiMe 3) 4 (1), a, B = 1923.3(3) pm, C = 2671.2(4) pm, V = 9.881(3) nm 3; tetragonal space group P4/ ncc; Z = 4; 1513 ( I > 2σ( I)) data; RI = 0.068. ZusammenfassungDas Gallium(I)tris(trimethylsilyl)silyl-Derivat {GaSi(SiMe3)3}4 (1) wird durch Umsetzung von Ga2Cl4-2Dioxan mit LiSi(SiMe3)3-3THF erhalten. Die Analyse der Kristallstruktur zeigt ein Tetramer mit einem nahezu regulären Gallium-Tetraeder-Gerüst. Der Mittelwert der Gallium-Gallium-Abstände betrügt 258.4 pm. Ab initio-Berechnungen verschiedener Gallium(I)-Verbindungen belegten eine erhöhte Stabilität von silyl-substituierten Clustern im Vergleich zu organyl-substituierten. Kristalldaten, mit Mo K -Strahlung; {GaSi(SiMe3)3 }4 · Si(SiMe3)4 (1), a, B = 1923.3(3) pm, C = 2671.2(4) pm, V = 9.881(3) nm3; tetragonal, Raumgruppe P4/ncc; Z = 4; 1513 (I > 2 σ(I)) Daten; RI = 0.068. 相似文献
20.
Three families of heterobimetallic compounds were obtained by reaction of [Mo(CO) 3(CH 3CN) 2(Cl)(SnRCl 2)] (R = Ph, Me) with P(4-XC 6H 4) 3 (X = Cl, F, H, Me, MeO). The type of compound obtained dependent on the solvent and concentration of the starting compound. So, [Mo(CO) 2(CH 3COCH 3) 2(PPh 3)(Cl)(SnRCl 2)]· nCH 3COCH 3 (R = Ph, n = 0.5; R = Me, n = 1) (type I) and [Mo(CO) 3{P(4-XC 6H 4) 3}(μ-Cl)(SnRCl 2)] 2 (R = Ph, X = Cl, F, H, Me, MeO; R = Me, X = Cl, F) (type II) were isolated from acetone solution in ca 0.05 M and 0.1 M concentrations, respectively. However, [Mo(CO) 3(CH 3CN) {P(4-XC 6H 4) 3}(Cl)(SnRCl 2)] (R = Ph, X = H; R = Me, X = Cl, F, H) (type III) were obtained from dichloromethane solution independently of the concentration used. All new complexes showed a seven-coordinate environment at molybdenum, containing Mo---Cl and Mo---Sn bonds. Mössbauer spectra indicated a four-coordination at tin for type III complexes. 相似文献
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