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1.
Reinhold Tacke Rüdiger Bertermann Andreas Biller Olaf Dannappel Martin Penka Melanie Pülm Reiner Willeke 《无机化学与普通化学杂志》2000,626(5):1159-1173
The syntheses of the zwitterionic spirocyclic λ5Si‐silicates 7–14 are described. The chiral zwitterions contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom, the ate and onium center being connected by an alkylene group. The zwitterions each contain two identical bidentate diolato(2–) ligands that formally derive from acetohydroximic acid or benzohydroximic acid. The stereochemistry and dynamic behavior of these compounds were investigated by experimental and theoretical methods. For this purpose, the zwitterionic λ5Si‐silicates 7–14 were studied by solution (1H, 13C, 29Si) and solid‐state (13C, 15N, and 29Si CP/MAS) NMR experiments. In addition, compounds 7 , 8 , 10 , 11 , and 13 were structurally characterized by single‐crystal X‐ray diffraction. The dynamic behavior (intramolecular enantiomerization) of 7 and 13 in solution was studied by VT 1H NMR experiments. These experimental studies were completed by ab initio investigations of the related anionic model species 15 . The chiral compounds 7–14 exist as (λ)‐ and (δ)‐enantiomers in the solid state and in solution. The trigonal‐bipyramidal structure of the respective Si‐coordination polyhedra, with the two carbon‐linked oxygen atoms in the axial sites, is the energetically most favorable one. The (λ)‐ and (δ)‐enantiomers of 7–14 are configurationally stable in solution on the NMR time scale ([D6]DMSO, room temperature). They undergo an intramolecular (λ)/(δ)‐enantiomerization (twist‐type mechanism), with an activation free enthalpy of δG{ = 72–73 kJ mol–1 (experimentally established for 7 and 13 ; calculated energy barrier for the model species 15 : 66.0 kJ mol–1). 相似文献
2.
Reinhold Tacke Rüdiger Bertermann Andreas Biller Olaf Dannappel Melanie Pülm Reiner Willeke 《欧洲无机化学杂志》1999,1999(5):795-805
The syntheses of the zwitterionic (molecular) spirocyclic λ5Si-silicates 5 – 9 are described. These chiral compounds contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom. The stereochemistry and dynamic behavior of 5 – 9 were investigated. For this purpose, compounds 5 – 9 were studied by solution-state NMR spectroscopy (1H, 13C, 29Si; including VT 1H-NMR studies of 9 ) and solid-state NMR spectroscopy (13C CP/MAS, 29Si CP/MAS). In addition, compounds 5 ·H2O, 7 , 8 , 9 ·H2O, and 9 ·2CH3CN were structurally characterized by single-crystal X-ray diffraction, and ab initio investigations of the zwitterion 8 and the related anionic model species 10 were carried out. 相似文献
3.
The syntheses of the zwitterionic (molecular) spirocyclic λ5Si-silicates 7 and 8 (SiO5 skeletons) and 10 – 12 (SiO4C skeletons) are described. These chiral compounds contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom. The pairs 7 / 11 and 8 / 12 are isoelectronic O/CH2 analogues and 10 – 12 represent a series of homologous compounds containing different alkylene spacers that connect the ate and onium center of these zwitterions. Compound 7 , 8 , and 10 – 12 were studied by single-crystal X-ray diffraction, solution-state (1H, 13C, 29Si) and solid-state (29Si CP/MAS) NMR spectroscopy, and VT 1H-NMR spectroscopy. The experimental investigations were completed by ab initio studies of the related anionic λ5Si-silicate 13 . 相似文献
4.
Synthesis and Crystal and Molecular Structure of Tetrafluoro[2-(pyrrolidinio)ethyl]silicate The zwitterionic tetrafluoro[2-(pyrrolidinio)ethyl]silicate ( 4 ) was synthesized by reaction of trimethoxy(2-pyrrolidinoethyl)silane ( 5 ) with hydrogen fluoride in ethanol/hydrofluoric acid at 0°C. The crystal and molecular structure of 4 was studied at ?100°C by single-crystal X-ray diffraction. In addition, 4 was characterized by solution-state NMR studies (CD3CN: 1H, 13C). 相似文献
5.
Reinhold Tacke Mathias Mühleisen Angel Lopez-Mras William S. Sheldrick 《无机化学与普通化学杂志》1995,621(5):779-788
Syntheses and Crystal Structure Analyses of New Zwitterionic Spirocyclic (Ammonioorganyl)bis[vic-arenediolato(2–)]silicates: Studies on the Structure of the λ5Si Coordination Polyhedra A new crystallographic modification ( 1-II ) of the zwitterionic λ5Si-spirosilicate [2-(pyrrolidinio)ethyl]bis[3,4,5,6-tetrabromobenzene-1,2-diolato(2 – )]silicate ( 1 ) was synthesized. In addition, two solvent-free crystallographic modifications ( 2-I, 2-II ) and two solvates ( 2 · Me2CO, 2 λ MeNO2) of the zwitterionic λ5Si-spirosilicate [(morpholinio)methyl]bis[2,3-naphthalenediolato(2 – )]silicate ( 2 ) were prepared. All new compounds were studied by 29Si-CP/MAS NMR spectroscopy and compounds 1-II (Pna21), 2 · Me2CO (P21/c), and 2 · MeNO2 (P21/n) were structurally characterized by single-crystal X-ray diffraction. 相似文献
6.
P,P′-(2,5-Dimethoxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic acid tetramethylester The title compound 1 is formed by reaction of the corresponding phosphonic acid 2 and orthoformicacidmethylester as a mixture of four stereoisomeres. The RRSS isomer was separated. It crystallizes in the triclinic space group P ?1 with a = 649.2 pm, b = 976.1 pm, c = 1 571.7 pm, α = 80.9°, β = 88.1°, γ = 78.6° and Z = 2. The 31P and 13C NMR spectra (4 and 5 spin systems) are discussed. 相似文献
7.
P,P′-(2,5-Dihydroxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic Acid The tetrahydrate 1 of the title compound crystallizes in the monoclinic space group P21/c with a = 845.8, b = 1 098, c = 981.7 pm, β = 113.02° and Z = 2. The anions of the oxonium compound (H3O+ · H2O)2(C4H10O12P42?) are layered by hydrogen bridges. The 1H, 13C and 31P NMR spectra (4 and 5 spin systems) are discussed. 相似文献
8.
A Cyclic Methylenediphosphinic Acid: 1,3‐Dihydroxy‐1,3‐dioxo‐1,2,3,4‐tetrahydro‐1λ5,3λ5‐[1,3]diphosphinine Strong acids protonate 1,3‐bis(dimethylamino)‐1λ5,3λ5‐[1,3]diphosphinine ( 5 ) to give the corresponding cation. The protonation is followed by hydrolytic cleavage of the dimethylamino groups resulting in the formation of the cyclic methylenediphosphinic acid ( 6 ). 相似文献
9.
The new compound C10H6P(S)[NSi(CH3)3]2P(S) ( 3 ) which contains a P2N2 heterocycle has been prepared in low yield by partial thermal decomposition of 1-{[N,N′-bis(trimethylsilyl)acetamidinium]sulfido}-3-(trimethylsilylamino)-1 H,3 H,1 λ5,3 λ5-naphtho[1,8 a,8-cd][1,2,6]thiadiphosphinine-1,3-dithione [CH3C{NHSi(CH3)3}2]+[C10H6P(S)(NHSiMe3)SP(S)2]– ( 2 ). Reaction of 2 with potassium hydroxide in acetonitrile gives the completely desilylated product [CH3C(NH2)2]+[C10H6P(S)(NH2)SP(S)2]– ( 4 ). The structures of the new compounds 3 and 4 were elucidated by FTIR and NMR spectroscopy methods and by X-ray structure analyses. 相似文献
10.
Ernst Ruch 《Angewandte Chemie (International ed. in English)》1977,16(2):65-72
Chemistry judging by its applications, physics according to its methods, and heavily reliant upon the tools of mathematics—that is what makes theoretical chemistry. And yet that is where its strength lies—in the variety of these sciences. It is quite natural that, in answer to specific problems, results and methods can sometimes be developed whose scope extends far beyond the original application. Rather it is a mark of quality if consequences can be found in chemistry and physics and the pathway leads via new mathematical procedures and concepts. Regrettably, any publication aiming to present such aspects will usually encounter little resonance since the linguistic confusion in science, its disciplines, and subdisciplines, lies like a veil over our understanding. The author nevertheless wishes to attempt to present, in a series of articles, results of research into chemical themes in a manner designed to appeal to the interest of chemists, without neglecting interdisciplinary aspects. All that is required to understand the argumentation is a lively interest. The first two articles are concerned with the chirality of molecules, and in particular with questions relating to the chirality phenomenon of molecules in the framework of molecular classes. In view of the algebraic nature of the mathematical methods adopted, it is not surprising that precise statements result. It appears of primary interest to establish the degree to which such statements can be considered valid for molecular models or molecules themselves. 相似文献
11.
1,1,3,3,5,5-Hexakis(dimethylamino)-λ5-[1,3,5]triphosphinine – Synthesis, Crystal Structure, and NMR Data Preparation of 1,1,3,3,5,5-hexakis(dimethylamino)-λ5-[1,3,5]triphosphinine ( 4 ) and the path of its formation from methyl-bis(dimethylamino)difluorophosphorane ( 1 ) and n-butyllithium are described. The chemical behaviour of compounds of type [R2P=CH–]n is compared with that of the isoelectronic dichlorophosphazenes [Cl2P=N–]n. The structure of 4 is eludicated by n.m.r. spectra and X-ray structural analysis. 相似文献
12.
Reaction of 1,′, 3,3′-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphete with S? H Acidic Compounds. Reaction of 1,′,3,3′-tetrakis(dimethyl-amino)-1λ5,3λ5-diphosphete ( 1 ) with hydrogen sulfide yields bis(dimethylamino)thiophosphonylmethylidene-methyl-bis(dimethylamino)phosphorane ( 5 ).Water eliminates dimethylamine from 5 and forms bis(dimethyl-amino)thiophosphonyl-methyl(dimethylamino)phosphonylmethylene 6 . The reaction of 1 with ethylmercaptane yields the 2,4-bis(ethylthio)-derivative of 1 , i.e. compound 8 and bis(dimethylamino)phosphanylmethylidene-methyl-bis(dimethylamino)phosphorane ( 9 ), which is also formed from 1 and 2,4,6-trimethylphenylphosphane. Thiophenol protonates 1 to give the corresponding cation which is isolated as its thiophenolate, 10 . Properties, nmr and mass spectra of 5, 6 and 8 – 10 are described and discussed. 相似文献
13.
Aleksandr G. Shipov Evgeniya P. Kramarova Elizaveta A. Mamaeva Oksana A. Zamyshlyaeva Vadim V. Negrebetsky Yuri E. Ovchinnikov Sergey A. Pogozhikh Alan R. Bassindale Peter G. Taylor Yuri I. Baukov 《Journal of organometallic chemistry》2001,620(1-2):139-149
Reactions of 2-sila-5-morpholinones, 4-acyl-2-silamorpholines and 4-acyl-2,6-disilamorpholines with electrophilic reagents generally lead to the opening of the sila- or disilacycle by cleavage of the Si–O bond with subsequent rearrangement to form five-membered chelate derivatives where the amide oxygen atoms coordinate with the silicon to form pentacoordinate silicon species. Multinuclear NMR spectroscopy and X-ray diffraction studies were used for structural investigation of the products. 4-Acyl-2,6-disilamorpholines initially form adducts with strong acids where the amide oxygen is protonated by the acid as demonstrated by X-ray crystallography. 相似文献
14.
Phosphorus(V)-Hydrazine-Sulfur(IV) Heterocycles with Twist-Boat Conformation . Unlike the corresponding unsubstituted compounds N-ethoxycarbonyl-substituted dihydrazidophosphoric acid derivatives do not react with thionylchloride under redoxdecomposition but yield sulfur containing sixmembered rings. In solution (NMR spectra) as well as in the crystal (X-ray structure analysis) the rings adopt unusual twist-boat conformations. Due to the rather bulky substituents high energies of interconversion between enantiomeric twist-forms are found: 75 ± 2 kJ/mol. 相似文献
15.
Vadim A. Pestunovich Natal’ya F. Lazareva Aleksander I. Albanov Mikhail G. Voronkov 《Journal of organometallic chemistry》2007,692(11):2160-2167
The synthesis and reaction behavior of pentacoordinate hydrochlorosilanes LCH2SiRHCl (L- 2-piperidonyl ligand, R = Me, Ph, Bn) are described. The intramolecular O-Si and N-Si coordination is discussed on the basis of the NMR data. The strength of the O-Si coordinate bond is nearly the same for chelates 5, 6, 8 irrespective of the equatorial substituent R at the silicon atom. However, the nature of R substituent markedly affects the stability of the complexes with the N-Si intramolecular bond. 相似文献
16.
17.
Ekkehard Fluck Gernot Heckmann Fred Rosche Matthias Westerhausen Ekaterina Gorbunowa 《无机化学与普通化学杂志》1995,621(9):1539-1546
Reactions of λ5-Diphosphetes with COS and CO2. Dihydro-λ5-Phosphetes 1,1,3,3-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphete, 1 , reacts with COS to yield the (3-oxo-3,4-dihydro-1λ5-phosphete-2-yl)-phosphonothioic bis(dimethylamide) 7 . Reaction of dimethyl substituted 1 , i.e. 1,1,3,3-tetrakis(dimethylamino)-2,4-dimethyl-1λ5,3λ5-diphosphete 4 , with COS and CO2 results in (3-oxo-2,3-dihydro-1λ5-phosphete-2-yl)-phosphonothioic bis(dimethylamide) 9 , and (3-oxo-2,3-dihydro-1λ5-phosphete-2-yl)-phosphonic bis(dimethylamide) 10 , respectively. Reaction mechanisms are suggested. 7, 9 and 10 are characterized by their properties, and their nmr, mass-, and ir-spectra. The results of X-ray structural analyses of 9 and 10 are reported and discussed. 相似文献
18.
Diphosphabenzenes. VII. Reactions of 1,1,3,3‐Tetrakis(dimethylamino)‐1 λ5, 3 λ5‐diphosphete with 5‐Cyano‐1‐pentine and 2‐(Cyanomethyl)‐1‐methylpyrrol 5‐Cyano‐1‐pentine reacts with the equimolar amount of the λ5‐diphosphete 1 to give the λ5‐diphosphinine (λ5‐diphosphabenzene) ( 3 ), while reaction with the double equimolar amount of 1 yields the λ5‐diphosphinine ( 4 ). The acyclic compount 6 is the main product of the reaction between 1 and 2‐(cyanomethyl)‐1‐methylpyrrol, 5 . Melting points of 4 · CH3CN and 6 , and mass, nmr and ir spectra of 3 , 4 , and 6 are reported. The crystal structure of 4 · CH3CN shows an open‐chain ylidic CPCP‐sequence, which is linked to a λ5‐diphosphinine via an ethylene bridge. The X‐ray structure analysis of 6 confirms the existence as an acyclic conjugated double ylid. 相似文献
19.
Stefan Plank Gernot Heckmann Wolfgang Schwarz Bernhard Neumüller Ekkehard Fluck 《无机化学与普通化学杂志》1999,625(10):1712-1720
Diphosphabenzenes. VI. New 1λ5, 3λ5-[1,3]Diphosphinines with Thio and Seleno Phosphonic Acid Groups – Preparation, Crystal Structure, NMR Data, and Coordination to PdII Preparation of N,N,N′,N′-tetraethyl-P-phenylethinyl phosphonothioacid diamide ( 2 ) and the corresponding phosphonoselenoacid diamide ( 3 ) are described. 2 and 3 react with 1,1,3,3-tetrakis(dimethylamino)-1λ5,3λ5-diphosphete ( 1 ) to yield 1λ5,3λ5-[1,3]diphosphinine derivatives 4 and 5 . With (bzl)2Cl2Pd 5 forms the coordination compound 6 . All new compounds 2–6 are characterized by their nmr and ir spectra, the structures of 4–6 are further elucidated by X-ray structural analyses. 相似文献
20.
Takayuki Kawashima Tomokazu Soda Renji Okazaki 《Angewandte Chemie (International ed. in English)》1996,35(10):1096-1098