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Jochen Pfalzgraf 《Journal of Geometry》1995,53(1-2):131-147
An application of constructions from so-called Bass-Serre theory to group spaces in noncommutative geometry is discussed motivated by the question how to make visible the interplay of different structures coming together in the notion of a group space. A compact summary of basic notions and constructions from Bass-Serre theory up to the structure theorem is developed; it should serve as a brief guideline for further applications. Concluding prospects indicate a way for generalizing the methods from a categorical point of view.Dedicated to Professor Johannes André on the occasion of his 70th birthday 相似文献
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The reaction between BaI2 · 2H2O and NaHFIP [HFIP = OCH(CF3)2] in a 1:1 stoichiometry gave the heterometallic compound NaBaI2(HFIP)(H2O)(THF)0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI2(DME)3 (2), trans-BaI2(DME)(triglyme) (3) and cis-BaI2(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI2 · 2H2O and NaTFA (TFA = O2CCF3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)2]I2 · C7H8 (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and 1H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4. 相似文献
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Mishra S Pfalzgraf LG Jeanneau E Chermette H 《Dalton transactions (Cambridge, England : 2003)》2007,(4):410-413
An ionic heterometallic species [Y(DMF)(8)][Cu(4)(micro(3)-I)(2)(micro-I)(3)I(2)](1) was isolated from a solution of CuI, NH(4)I and YI(3)(Pr(i)OH)(4) in DMF-isopropoxyethanol, and was converted in a confined environment by progressive substitution of the DMF ligands with water molecules first into a 1D zig-zag structure [Y(DMF)(6)(H(2)O)(2)][Cu(7)(micro(4)-I)(3)(micro(3)-I)(2)(micro-I)(4)(I)](1infinity)(2) and finally into a 2D sheet [Y(DMF)(6)(H(2)O)(3)][Cu(I)(7)Cu(II)(2)(micro(3)-I)(8)(micro-I)(6)](2infinity)(3) by H-bond templating. 相似文献
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Lauren C. Cauro‐Gamet Liliane G. Hubert‐Pfalzgraf Sylvain Lecocq 《无机化学与普通化学杂志》2004,630(12):2071-2077
The reactions between Ti(OR)4 and allylacetatoacetate (HAAA) in 1:1 or 1:2 stoichiometry at rt gave Ti2(OR)6(AAA)2 R = Et ( 1 ), iPr ( 2 ) and Ti(OR)2(AAA)2 R = Et ( 3 ), iPr ( 4 ) species. A monosubstituted derivative Ti2(OiPr)6(AMP)2 ( 5 ) was isolated with allylmethylphenol (AMPH). 1 and 5 were characterized by single crystal X‐ray diffraction. Their molecular structures consist of dimers with the polymerizable ligands in terminal positions andbridging alkoxide ligands assembling five and six‐coordinated metal atoms, respectively. The Ti‐O bond lengths of 1 are in the range 1.76(1) to 2.11(1) Å with the variation Ti‐OEt < Ti‐μ‐OEt < Ti‐η2‐O (allylacetatoacetate). All compounds were characterized by FT‐IR and 1H NMR. The possibility to accede to more extended arrays either by hydrolysis or by radical initiated homo‐ or co‐polymerization reactions was investigated for the allylacetato derivatives as well as for Ti(OiPr)2(AAEMA)2 AAEMA = [2‐(methacryloyloxy)ethylacetoacetato] for the latter reactions. 相似文献
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J. Pfalzgraf 《Geometriae Dedicata》1986,21(2):193-203
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一、TheProblem .Letf(x) =ax2 bx c ax2 px q,wherea >0 ,b2 - 4ac≤ 0andp2 - 4aq≤ 0 .OurProblemis“Whetherdoesminx∈Rf(x)exis?Moreover ,,ifminx∈Rf(x)exists,thenminx∈Rf(x)=?andinthiscasex =?” .Naturally ,weknowthatminx∈Rf(x)existsfromtheknowledgeofmathematicalanalysis.Also,wecangivethe… 相似文献
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