共查询到20条相似文献，搜索用时 15 毫秒
1.
Bruce W. Tattershall Kathryn E. Holmes Catherine Tweedy Gina C. Valks 《无机化学与普通化学杂志》2008,634(10):1703-1710
Reaction of a mixture of bicyclic phosphorus sulfide selenide iodides α‐P4SnSe3−nI2 (n = 0–3) with PriNH2 and Et3N gave corresponding diamides α‐P4SnSe3−n(NHPri)2 (n = 0–3) and imides α‐P4SnSe3−n(μ‐NPri) (n = 2–3), identified in solution by 31P NMR. In one isomer of α‐P4S2Se(μ‐NPri), the C2 symmetry of imides such as α‐P4S3(μ‐NPri) was broken, allowing relative assignment of 2J NMR couplings to the PNP bridge and the PSP bridge opposite to it. The coupling through the sulfur bridge was found to be reduced to ca. zero, in contrast to previous assumptions for this class of compounds. Ab initio models were calculated at the MPW1PW91/svp level for the sulfide selenide imides and for a selection of bond rotamers of the diamides, and at the MPW1PW91/LanL2DZ(d) level for the sulfide selenide diiodides. Different skeletal isomers were prevalent for the mixed chalcogenide diamides than for the diiodides, showing that exchange of chalcogen between skeletal positions took place in the amination reaction even at room temperature. Similar differences to those observed were predicted by the models, suggesting that equilibrium was attained. 相似文献
2.
Henning Hopf Cornelia Mlynek Dagmar Klein Marit Traetteberg Pirkko Bakken 《European journal of organic chemistry》2001,2001(7):1385-1391
The highly strained conjugated aldehyde 3-tert-butyl-4,4-dimethyl-2-pentenal (3,3-di-tert-butylpropenal; abbreviated D33; 4 ) has been prepared, and its molecular structure and conformation have been studied experimentally by the gas electron diffraction method and by theoretical ab initio (HF/6-31G*) calculations. The propenal skeleton assumes an anti conformation, and the steric strain is primarily manifested in the following structural details: The C=C−C angle is substantially larger than normal [GED: 132.6(7)°; HF/6-31G*: 132.5°]; the (Z)-oriented tert-butyl group is twisted to a nearly staggered position relative to the C=C double bond, forming a cogwheel system with the other tert-butyl group, which has the normal eclipsed conformation relative to C=C; the C3−CtBu (formally sp2−sp3) bonds are elongated compared to those in unstrained compounds, and are longer than the (formally sp3−sp3) C−CH3 bonds. 相似文献
3.
Bohumil Štíbr Josef Holub Mario Bakardjiev Drahomír Hnyk Oleg L. Tok Wolfgang Milius Bernd Wrackmeyer 《欧洲无机化学杂志》2002,2002(9):2320-2326
The reaction of the carborane nido-5,6-C2B8H12 ( 1 ) with PCl3 in dichloromethane in the presence of a “proton sponge” [PS = 1,8-bis(dimethylamino)naphthalene], followed by hydrolysis of the reaction mixture, resulted in the isolation of the eleven-vertex nido-phosphadicarbaboranes 7,8,9-PC2B8H11 ( 2 ) and 10-Cl-7,8,9-PC2B8H10 ( 10-Cl-2 ), depending on the ratio of the reactants. Both of these compounds can be deprotonated by PS to give the nido anions [7,8,9-PC2B8H10]− ( 2− ) and [10-Cl-7,8,9-PC2B8H9]− ( 10-Cl-2− ). The molecular geometries of all compounds were optimized by ab initio methods at a correlated level of theory [RMP2(fc)] using the 6-31G* basis set and their correctness was assessed by a comparison of the experimental 11B NMR chemical shifts with those calculated by the GIAO-SCF/II//RMP2(fc)/6-31G* method. Moreover, the structure of 10-Cl-2 − was determined by an X-ray diffraction analysis. The anionic compounds 2− and 10-Cl-2− are analogs of the Cp (Cp = η5-C5H5−) anion. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002) 相似文献
4.
The bicyclic dioximes 4–6 and dimethoximes 7–9 , which contain the functional groups in opposite positions of bridged eight-membered rings, were synthesized. Their conformational properties and transannular interactions were investigated by spectroscopic (PE, 13C NMR) and theoretical (MMX, AM1, ab initio HF, and B3LYP) methods. While in the 3,7-disubstituted bicyclo[3.3.1]nonane derivatives 5 and 8 the eight-membered ring has a CC conformation favourable for through-space interactions of the π(CN) orbitals, in the bicyclo[3.3.0]octane derivatives 4 and 7 as well as the 2,6-disubstituted bicyclo[3.3.1]nonanes 6 and 9 the functional groups are in geometric orientations that are unfavourable for such interactions. Through-space orbital interactions in the molecules with favourable conformations lead to a splitting of the π(CN) MOs of 0.4–0.6 eV. 相似文献
5.
The dioximes 4–6 and the dimethoximes 7–9 , which contain the functional groups in opposite positions of a six-, eight-, or ten-membered ring, were synthesized. Their conformational properties and transannular interactions were investigated by spectroscopic (PE, 13C NMR) and theoretical (MMX, AM1, ab initio HF, and B3LYP) methods. While the cyclooctane derivatives 5 and 8 have conformations favourable for through-space interactions of the π(CN) orbitals, in the other compounds no such interactions can be ascertained. Through-space orbital interactions in the molecules with an eight-membered ring lead to a splitting of the π(CN) MOs of 0.4 eV. 相似文献
6.
The aromatic stabilization of cyclic phosphenium cations (general type C2N2P+) was studied by experimental methods (synthesis, multinuclear NMR, single crystal X-ray crystallography) and quantum chemical calculations (ab initio methods). The structures of the 1,3,2-diazaphosphole derivatives [(tBuN–CH=CH–NtBu)P+]Cl− ( 1 ), (tBuN–CH2–CH2–NtBu)P–Cl ( 2 ), [(tBuN–CH=CH–NtBu)P]+PF6− ( 3 ) and [(tBuN–CH2–CH2-NtBu)]P+PF6− ( 4 ) were examined by single crystal X-ray diffraction. The chloro phosphane [(tBuN–CH=CH–NtBu)P]+Cl− ( 1 ) has an ionic P–Cl bond and contains an aromatically stabilized phosphenium cation [shortest distance P···Cl = 275.9(2) pm], while the CC-saturated compound (tBuN–CH2–CH2–NtBu)P–Cl ( 2 ) is covalent. The two chloro-phosphanes 1 and 2 differ sharply in their volatility and solubility in organic solvents. Compound 2 is soluble in hydrocarbons and sublimes readily at 90 °C/0.1 Torr but 1 is insoluble in hexanes and not volatile below 180 °C/0.1 Torr. The degree of aromatic stabilization in the phosphenium cation 1 was investigated by ab initio methods. For the model cations [RN–CH2–CH2–NR]P+ and [(RN–CH=CH–NR)P]+, thermochemical stabilization energies of 25.8 kcal · mol−1 (R = H) and 28.1 kcal · mol−1 (R = Me) were obtained from isodesmic hydrogenation reactions at the RHF/MP2/6–31G*//RHF/6–31G* level. 相似文献
7.
Reaction of bicyclic β‐P4S3I2 with enantiomerically pure (R)‐Hpthiq (1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline) and Et3N gave a solution of a single diastereomer of the unusually stable diamide β‐P4S3(pthiq)2, accounting for 83 % of the phosphorus content. Despite the steric bulk of the substituents, each amide group of this could adopt either of two rotameric positions about their P–N bonds, so that, at 183 K, 31P NMR multiplets for four rotamers could be observed and the spectra of three of them analysed fully. The large 2J(P–P–P) coupling became greater (253, 292, 304 Hz) with decreasing abundance of the individual rotamers. The rotamers were modelled at the ab initio RHF/3–21G* level, and relative NMR chemical shifts predicted by the GIAO method using a locally dense basis set, allowing the observed spectra to be assigned to structures. Calculations at the same level for the model compound α‐P4S3(pthiq)Cl confirmed the assignments of low‐temperature rotamers of α‐P4S3(pthiq)I reported previously. Changes in observed P–P coupling constants and 31P chemical shifts, on rotating a pthiq substituent, could then be compared between β‐P4S3(pthiq)2 and α‐P4S3(pthiq)I, confirming both sets of assignments. The most abundant rotamer of β‐P4S3(pthiq)2 was not the one with the least sterically crowded sides of both pthiq substituents pointing towards the P4S3 cage, because of interaction between the two substituents. Only by using a DFT method could relative abundances of rotamers of β‐P4S3(pthiq)2 be predicted to be in the observed order. Use of racemic Hpthiq gave also the two diastereomers of β‐P4S3(pthiq)2 with Cs symmetry, for which the room temperature 31P{1H} NMR spectra were analysed fully. 相似文献
8.
Bruce W. Tattershall Julian G. Knight Mark J. Andrews Claire L. Booth 《无机化学与普通化学杂志》2006,632(3):425-432
Reactions of bicyclic α‐P4S3I2 with Hpthiq gave solutions containing α‐P4S3(pthiq)I and α‐P4S3(pthiq)2, where Hpthiq is the conformationally constrained chiral secondary amine 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline. The expected diastereomers have been characterised by complete analysis of their 31P{1H} NMR spectra. Hindered P–N bond rotation in the amide iodide α‐P4S3(pthiq)I caused greater broadening of peaks in the room‐temperature spectrum of one diastereomer than in that of the other. At 183 K, spectra of two P–N bond rotamers for each diastereomer were observed and analysed. The minor rotamers showed strong evidence for steric crowding, having large diastereomeric differences in 1J(P–P) and 2J(P–S–P) couplings (49 Hz, 16 % of value, and 4.4 Hz, 19 % of value, respectively). 相似文献
9.
Markus Henn Klaus Jurkschat Ralf Ludwig Michael Mehring Katja Peveling Markus Schürmann 《无机化学与普通化学杂志》2002,628(13):2940-2947
The reaction of the organolithium derivative {2, 6‐[P(O)(OEt)2]2‐4‐tert‐Bu‐C6H2}Li ( 1 ‐Li) with [Ph3C]+[PF6]— gave the substituted biphenyl derivative 4‐[(C6H5)2CH]‐4′‐[tert‐Bu]‐2′, 6′‐[P(O)(OEt)2]2‐1, 1′‐biphenyl ( 5 ) which was characterized by 1H, 13C and 31P NMR spectroscopy and single crystal X‐ray analysis. Ab initio MO‐calculations reveal the intramolecular O···C distances in 5 of 2.952(4) and 2.988(5)Å being shorter than the sum of the van der Waals radii of oxygen and carbon to be the result of crystal packing effects. Also reported are the synthesis and structure of the bromine‐substituted derivative {2, 6‐[P(O)(OEt)2]2‐4‐tert‐Bu]C6H2}Br ( 9 ) and the structure of the protonated ligand 5‐tert‐Bu‐1, 3‐[P(O)(OEt)2]2C6H3 ( 1 ‐H). The structures of 1 ‐H, 5 , and 9 are compared with those of related metal‐substituted derivatives. 相似文献
10.
J. Grobe Prof. Dr. A. Armbrecht D. Le Van B. Krebs J. Kuchinke M. Läge E.-U. Würthwein 《无机化学与普通化学杂志》2001,627(6):1241-1247
Perfluoro-2-phosphapropene ( 1 ) reacts with diazo compounds R(H)C=N2 (R = H ( 2 a ), Ph ( 2 b ), CO2Et ( 2 c ), Me3Si ( 2 d )) at low temperatures regioselectively yielding via 1,3-H shift the novel 1,2,3-diazaphospholes 4 a – d . The mesomerically stabilized compounds 4 b and 4 c were characterized by NMR spectroscopy and single crystal X-ray diffraction studies. Using diphenyldiazomethane 5 as partner for 1 , the cycloaddition is spontaneously followed by N2 elimination to give the crystalline phosphirane derivative 7 . The analogous reaction of 1 with 9-diazofluorene 9 unexpectedly leads to the so-far unknown 1,2-diphosphinane compound 11 . Quantum chemical calculations for the gas phase on DFT and RHF level prove that for both the perhydro- and the perfluoro-2-phosphapropene the [3 + 2]-cycloaddition is kinetically determined and that, due to high stability of the products, the thermodynamic equilibrium with the slightly more stable isomers is not accessible. 相似文献
11.
Henning Hopf Ralf Hänel Marit Trætteberg Pirko Bakken 《European journal of organic chemistry》1998,1998(3):467-472
The highly strained hydrocarbon 4-tert-butyl-5,5-dimethyl-1,3-hexadiene ( 3 ) has been prepared and its molecular structure and conformation have been studied experimentally by the gas-electron diffraction method and by theoretical ab initio (HF-6-31G*) calculations. The 1,3-diene skeleton assumes an anti conformation, and the sterical strain primarily manifests itself in the following structural details: The butadiene C=C−C angle on the substituted side is larger than normal (GED: 128.2°; HF-6-31G*: 132.7°); the Z-oriented tert-butyl group is rotated to a nearly staggered position relative to the C1=C2 double bond, forming a cogwheel system together with the other tert-butyl group, which has the normal eclipsed conformation relative to C1=C2; the C1−CtBu and C−CH3 bonds are both elongated compared to those in unstrained compounds, and the formally C(sp2)−C(sp3) C1−CtBu bonds are longer than the formally C(sp3)−C(sp3) ones in the methyl groups. 相似文献
12.
Gernot P. Weinberger;Florian Sommer;Ana Torvisco;Roland C. Fischer;Michaela Flock; 《欧洲无机化学杂志》2020,2020(39):3778-3785
The novel diphosphatrisilanes {(R2P-Si(SiMe3)2-)2-SiMe2} [R = Ph, H] and the cyclophosphatrisilabutanes {R–PSi3} [R = H, SiMe3] have been prepared via salt metathesis reactions between phosphanides and 2,4-dihalogenated pentasilanes and characterized via NMR spectroscopy. The experimental results were supported by DFT calculations. Although P–Si bond formation was observed in all cases, the outcome of the reactions varied depending on the nature of ligands on the phosphanides, forming either linear diphosphatrisilanes or cyclic phosphatrisilacyclobutanes. DFT studies were performed to get a better understanding of the reactions. The precursor silanes were fully characterized using NMR spectroscopy and single-crystal X-ray diffraction and offer interesting building blocks. In addition, a modified route for the synthesis of P(TMS)3 was successfully carried out, achieving high yields of up to 73 %, circumventing the use of white phosphorus and phosphine gas during the reaction. 相似文献
13.
Jan B. M. Wit Gerno T. van Eijkel Franciscus J. J. de Kanter Marius Schakel Andreas W. Ehlers Martin Lutz Anthony L. Spek Koop Lammertsma 《Angewandte Chemie (International ed. in English)》1999,38(17):2596-2599
Highly strained methylenephosphiranes are formed in the reaction of the new electrophilic phosphinidene complex [iPr2N−P=Fe(CO)4] with allenes. Remarkably, reaction with diallenes at 0°C also leads to a phosphirane, which rearranges upon warming to room temperature to a bis-isopropylidenephospholene (see scheme). 相似文献
14.
Olaf Schmidt Andr Fuchs Dietrich Gudat Martin Nieger Wilfried Hoffbauer Edgar Niecke Wolfgang W. Schoeller 《Angewandte Chemie (International ed. in English)》1998,37(7):949-952
The butadiene-like phosphanylcarbene 2 is, according to ab initio calculations, the intermediate in the conversion of 1 into 3 in the solid state [Eq. (a)]; it is only 1.3 kJ mol−1 higher in energy than 1 . For this conversion, only minor changes in the endocyclic bonds are required throughout the entire reaction. R2N=2,2,6,6-Me4C5H6N. 相似文献
15.
Minh Tho Nguyen Alk Dransfeld Luc Landuyt Luc G. Vanquickenborne Paul v. R. Schleyer 《欧洲无机化学杂志》2000,2000(1):103-112
Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 ( 1 ), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6–311G(d,p) method based on MP2/6–31G(d,p) geometries and corrected for zero-point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6–311++G(3df,2p). The cyclic trans-triphosphirane ( 1a ) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldi-phosphene (H2P–PPH). The decrease of ring strain in three-membered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P–P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C3v-symmetric 1b (all-cis) but also in 1a (Cs). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo-(CH3)3 –n(PH)n and their values were obtained: PA( 1a ) = 777 ±10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ±10 kJ/mol. Heats of formation are evaluated as follows (ΔH°f0 at 0 K in kJ/mol): 1a , 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a ), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IEa) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a . The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift). 相似文献
16.
17.
Bernd Wrackmeyer Hans-Jörg Schanz Matthias Hofmann Paul von R. Schleyer Roland Boese 《欧洲无机化学杂志》1999,1999(3):533-537
Hydroboration of bis(diethylboryl)ethyne ( 1 ) with tetraethyldiborane(6) leads to a B-ethyl-substituted tetracarba-nido-octaborane 2 , a spiro-carborane 3 , which belongs to the 2,3,5-tricarba-nido-carborane family, and a hexacarba-arachno-dodecaborane(12) 4 , along with polymeric material. The X-ray structure analysis of carborane 2 , determined here, is fully consistent with the structure deduced earlier from NMR data. The structure of 3 in solution was established by theoretical analysis of its NMR data. Ab initio calculations of the structures of 2b and 3b ( b denotes the B-metyhl-substituted derivatives) and the comparison of calculated with experimental NMR data support the suggested structures of 2 and 3 in solution. The calculated structure of the carborane cage of 2a also agrees with the experimental geometry of 2 . 相似文献
18.
Preparation, Characterization, and Structure of Functionalized Fluorophosphaalkenes of the Type R3E–P=C(F)NEt2 (R/E = Me/Si, Me/Ge, CF3/Ge, Me/Sn) P‐functionalized 1‐diethylamino‐1‐fluoro‐2‐phosphaalkenes of the type R3E–P=C(F)NEt2 [R/E = Me/Si ( 2 ), Me/Ge ( 3 ), CF3/Ge ( 4 ), Me/Sn ( 5 )] are prepared by reaction of HP=C(F)NEt2 ( 1 , E/Z = 18/82) with R3EX (X = I, Cl) in the presence of triethylamine as base, exclusively as Z‐Isomers. 2–5 are thermolabile, so that only the more stable representatives 2 and 4 can be isolated in pure form and fully characterized. 3 and 5 decompose already at temperatures above –10 °C, but are clearly identified by 19F and 31P NMR‐measurements. The Z configuration is established on the basis of typical NMR data, an X‐ray diffraction analysis of 4 and ab initio calculations for E and Z configurations of the model compound Me3Si–P=C(F)NMe2. The relatively stable derivative 2 is used as an educt for reactions with pivaloyl‐, adamantoyl‐, and benzoylchloride, respectively, which by cleavage of the Si–P bond yield the push/pull phosphaalkenes RC(O)–P=C(F)NEt2 [R = tBu ( 6 ), Ad ( 7 ), Ph ( 8 )], in which π‐delocalization with the P=C double bond occurs both with the lone pair on nitrogen and with the carbonyl group. 相似文献
19.
An ab initio study of the importance of the phosphorus atom in PHY, PY2, POY2 (Y=–H, –CH3, –NH2, –OH and –F) functional groups is presented. Methods like HF, DFT, MP(2,4), QCISD(T), CCSD(T) are used to estimate structural and energetic behaviour and obtain charge distribution. The radicals and their positive and negative ions are considered as well as neutral and negatively charged organic compounds in order to compare these situations. By the use of different properties, the influence of the phosphorus containing groups and the importance of the phosphorus atom in these substituents is discussed and clarified. 相似文献
20.
《Comptes Rendus Chimie》2015,18(9):935-944
Peracetylated d-glucopyranose has a high solubility in CO2 and can be a promising phase-change physical solvent or absorbent for CO2, as reported recently. However, peracetylated d-glucopyranose is unstable under acidic atmospheres, especially in sulfur-containing waste gases, and the possibly major decomposition products are 2,3,4,6-tetra-O-acetyl-d-glucopyranose, 1-thiol-d-glucopyranose tetraacetate, and 1-mercaptoethyl-d-glucopyranose tetraacetate. Therefore, it is highly interesting to investigate the interaction between CO2 and these three compounds using ab initio calculations, including geometry optimizations with HF/3-21G, B3LYP/6-31+G** and single-point energy calibration with MP2/aug-cc-pVDZ. The results indicate that the electrostatic interactions between the substrates and CO2 are mainly influenced by the interaction distance and the numbers of negative charge donors or the interacting pairs involved in the complex. It is furthermore found that ΔE increases significantly if S and O atoms could interact with CO2 simultaneously. The binding energy is irrelevant if one considers the chemical environment of the O atom (i.e. OAc, OE or OS) or the S atom (i.e. SEt or SH), and the electronegativity difference between the S and O atoms. The three substrates studied are still excellent CO2-philes, although their average ΔE (–20 kJ/mol) is slightly lower than that of peracetylated d-glucose (–22 kJ/mol), which has one more O atom that can interact with CO2. Therefore, the applications of carbohydrates can be expanded to include adsorbents for CO2, SO2 or both, and the functional groups attached to the carbohydrate can vary from those to the acetyl groups. 相似文献