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1.
63Cu-NMR.-Spectra of Cu(CH3CN)4X (X = ClO, BF, PF) and Cu(C5H5N)4X (X = ClO, BF) in solution are reported at different temperatures and concentrations. The influence of temperature on the linewidth and chemical shift indicates an equilibrium of Cu(CH3CN) and Cu(C5H5N) with another complex of lower symmetry. The preferential solvation of Cu (I) by pyridin in a mixture acetonitrile/pyridine is clearly shown.  相似文献   

2.
Polyacetylene, (CH)x, has been doped with trimethyloxonium hexachloroantimonate, (CH3)3O+SbCl(1), in dichloromethane and acetonitrile. The maximally doped (CH)x films have moderate conductivities [σRT(CH2Cl2) = 10, σRT(CH3CN) = 0.7 Ω?1 cm?1]. Reactions between 1 and (CH)x CH2Cl2 or CH3CN were followed in situ by 1H nuclear magnetic resonance spectroscopy and x-band electron spin resonance spectroscopy. It was found that the reactions in the two solvents are different. In dichloromethane the dopant is SbCl5, which forms from the decomposition of 1, and doping proceeds by electron removal from (CH)x chains. Based on the ESR signal loss, an estimate can be made of the diffusion rate of SbCl5, into the (CH)x fibrils in CH2Cl2; it is found to be ca. 10?17 cm2/s. In acetonitrile the dopant appears to be either CH3CNCH, H+, CH, or a combination of one or more of these dopants. It is postulated that the CH3CNCH, CH, and/or H+ dopant covalently binds to the (CH)x chain. X-ray photoelectron spectra show that films doped with excess 1 in both solvents have approximately one SbCl per 33 CH units.  相似文献   

3.
The thermodynamics of the reaction of an ethylene molecule with the Cp2TiCH3Cl/Al(CH3)2Cl system (Cp = η5-C5H5), as a model for olefin polymerization with homogeneous Ziegler-Natta catalysts, was investigated via quantum mechanical DFT calculations. The comparison of the calculated energies for three possible titanium-olefin coordinated intermediates, the ionic complex Cp2TiCH3(C2H4)+/Al(CH3)2Cl, the bimetallic complex Cp2TiCH3(C2H4)δ+ · Al(CH3)2Cl and the olefin-separated ion pair Cp2TiCH/C2H4/Al(CH3)2Cl, shows that the most feasible polymerization mechanism occurs via olefin-separated ion pair.  相似文献   

4.
The reactions indicated in the title have been studied in terms of direct processes and complex formation. Quantum-chemical methods have been applied to the passage of an acid (H+, CH, X+) from CH3X to CH3X, and the abstraction of a radical (H· CH, X·) from CH3X by CH3X. It has been shown that a complex represented by a dimer of a methyl-halide radical cation, (CH3X), with a two-center three-electron bond X? X, has fairly high stability. These investigations were based on non-empirical quantum-chemical calculations, the results being systematically compared with experimental determinations. Some calculations included all electrons (X=F, Cl, Br), others were based on relativistic pseudopotentials (X=F through At). The two sets of calculations agree qualitatively with each other and with experimental observations.  相似文献   

5.
Synthesis and Structure Investigations of Iodocuprates(I). XV Iodocuprate(I) with Solvated Cations: [Li(CH3CN)4] [Cu2I3] and [Mg{(CH3)2CO}6][Cu2I4] [Li(CH3CN)4][Cu2I3] 1 and [Mg((CH3)2CO)6][Cu2I4] 2 were prepared by reactions of CuI with LiI in acetonitrile and of CuI with MgI2 in acetone. 1 crystallizes orthorhombic, Pnma, a = 552.7(2), b = 1258.8(8), c = 2516(1) pm, z = 4. [Li(CH3CN)4]+ cations are located between rod packings of CuI4 tetrahedra double chains [(CuI2/2I2/4)2]? parallel to the axis. Short intermolecular anion/cation contacts were observed. The crystal structure of 2 (monoclinic, P21/n, a = 1840(2), b = 1059.2(2), c = 1879(2)pm, β = 112.94(4)°, z = 4) is built up by [Mg((CH3)2CO)6]2+ cations forming a simple hexagonal sphere packing. The binuclear anions [Cu2I4]2? occupy holes in the trigonal prismatic channels formed by the cations.  相似文献   

6.
The α-distonic sulphur-containing ion $ {}^ \cdot {\rm CH}_2 \mathop {\rm S}\limits^ + \left({{\rm CH}_3 } \right)_2 $ has been generated by transfer of CH from ionized oxirane to dimethyl thioether and distinguished from the molecular ion of ethyl methyl thioether by collision induced dissociation (CID) experiments. In particular, the α-distonic ion expels CH2 to a minor extent following collision, whereas the molecular ion of ethyl methyl thioether does not undergo this reaction. The metastable C3H8S ions formed by CH transfer to dimethyl thioether and ionization of ethyl methyl thioether decompose by competing losses of CH3R˙, CH4 and C2H4. The elimination of ethene is taken as evidence for isomerization of the α-distonic ion to the molecular ion of ethyl methyl thioether prior to spontaneous dissociation. Evidence for the formation of stable α-distonic sulphur-containing ions by transfer of CH from ionized oxirane to methyl phenyl thioether has not been obtained. The collision-induced and spontaneous reactions of the ions formed by CH transfer to methyl phenyl thioether indicate that a mixture of the radical cations of CH3C6H4SCH3, C6H5SCH2CH3 and C6H5CH2SCH3 is generated implying that attack on the phenyl group occurs in addition to a formal insertion of a methylene entity in a C? S bond.  相似文献   

7.
Reactions of monosubstituted alkenes RCH = CH2 and [Re(η5–C5H5)(CH2Cl2) (NO)(PPh3)]+BF give complexes ([Re(η5–C5H5))(CH2?CHR)(NO) (PPh3)]+BF ( 1a–g ) in 63–99% yields as mixtures of (RS,SR)- and (RR,SS)-diastereoisomers ( 1a (R = Me), 66:34; 1b (R = Pr), 63:37; 1c (R = PhCH2), 70:30; 1d (R = Ph), 75:25; 1e (R = i-Pr), 64:36; 1f (R = t-Bu), 84:16; 1g (R = Me3Si), 69:31; Scheme 2). These differ in the C?C enantioface bound to the chiral Re fragment. In most cases, the analogous reactions of RCH?CH2 and [Re(η5–C5H5) (C6H5Cl)(NO)(PPh3)]+ BF give comparable results. When 1a – e , g are heated in PhCl at 95–100°, equilibration to 96:4, 97:3, 97:3, 90:10, > 99:< 1, and > 99:< 1 (RS,SR)/(RR,SS) mixtures occurs (79–99% recoveries; Tables 1 and 2). Thus, thermodynamic enantioface-binding selectivities are much higher than kinetic binding selectivities. This phenomenon is analyzed in detail. A crystal structure of (RS,SR)- 1e (monoclinic, P21/c, a = 10.256(1) Å. b = 17.191(1) Å, c = 16.191(1) Å, β = 101.04(1)°, Z = 4) shows that the Re–C(1)–C(2) plane (see Fig.2) is nearly coincident with the Re–P bond (angle 15°), and that the i-Pr group is ‘syn’ to the nitrosyl ligand.  相似文献   

8.
Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf, AsF, SbF, I (incommensurate), and 3:2 with tetrahedral anions BF?4, CIO?4, ReO?4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.  相似文献   

9.
Intermediate neglect of differential overlap (INDO ) calculations were used to study two structures of C60NH: one of C, geometry with a bridging NH across the bond between two fused six-membered rings in C60 and the other of Cs geometry with a bridging NH across the bond between a five- and a six-membered ring. We calculated the most stable isomer of C60NH to be of C, symmetry. It was found that the C isomer has a protonated aziridine structure with a bridging C? C bond length of 0.1520 nm. The electronic spectra of both isomers of C60NH were calculated. Comparisons were made with the isoelectronic molecules C60O and C60CH2, cases in which the calculated electronic spectra for the most stable isomers C60O (C) and C60CH2 (C) are in good agreement with recent experimental results. © 1995 John Wiley & Sons, Inc.  相似文献   

10.
On the Insertion into the Lanthanide–Carbon Bond. Synthesis and Structure of [Cp Sm(C6H5CH2NNO)]2 and [K(18-crown-6)Cp Yb(NCS)2] The compound [CpSm(CH2C6H5)(thf)] was investigated, regarding its reactions with small molecules. The main subject was to detect an insertion into the Ln–C bond. With N2O an insertion reaction is observed, yielding the dimer [CpSm(C6H5CH2NNO)]2 ( 1 ). The structural data of 1 was collected by a single crystal X-Ray diffraction analysis. (Space group P 1, Z = 1, a = 982.8(2) pm, b = 1052.2(2) pm, c = 1383.8(3) pm, α = 89.29(3)°, β = 73.64(3)°, γ = 66.41(3)°). In the dimer, the two Samarium ions are linked via an (η1 : η2) bridge by two benzyl diazotato ligands. A nearly planar six-membered central Sm2N2O2-ring is formend. Two pentamethylcyclopentadienyl ligands complete the coordination sphere of each Samarium ion, which are thus surrounded by four ligands each and have a distorted tetrahedral coordination geometry. An insertion of a SCN fragment in the Ln–C bond could not be observed. The substitution of the benzyl ligand leads to a polymeric chain structure. The new compound [K(18-crown-6)CpYb(NCS)2] 2 contains a tetrahedrally coordinated Yb(III)-ion. (Space group P21/n}, Z = 4, a = 1640.6(3) pm, b = 1482.2(3) pm, c = 1674.5(3) pm, β = 102.82(1)°).  相似文献   

11.
Poly(vinyl alcohol) (PVA)/poly(vinyl acetate) (PVAc) microspheres with a skin/core structure were prepared through the heterogeneous surface saponification of PVAc microspheres suspension‐polymerized. The PVA skin formed through the heterogeneous saponification was hydrogel swellable in water. In addition, to obtain monodisperse PVA/PVAc microspheres having various skin/core ratios and morphologies, the ion‐specificities to the heterogeneous saponification were investigated using SO, Cl?, NO, Br?, and I? for anions and Li+, Na+, and K+ for cations, respectively. The ions were not specific significantly to the rate of the heterogeneous saponification, while were related to the degree of saponification (DS). DSs had different values between by weight loss (DSw) and by proton nuclear magnetic resonance spectroscopy (DSNMR) measurements. The order of DSws was SO < Cl? < NO < Br? < I? for anions and K+ < Na+ < Li+ for cations, and that of DSNMRs, I? < Br? < NO < Cl? < SO for anions and Li+ < Na+ < K+ for cations. The differences in values between DSws and DSNMRs were caused by the dissolution of PVA skin and were significantly decreased for SO. The peaks at melting temperature of PVA were sharp and their areas were large for ions deswelling PVA skins.  相似文献   

12.
A systematic investigation on the SN2 displacement reactions of nine carbene radical anions toward the substrate CH3Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6‐31+G (d, p)/relativistic effective core potential (RECP), 6‐311++G (d, p)/RECP, and aug‐cc‐pVTZ/RECP. The studied models are CX1X2?? + CH3Cl → X2X1CH3C? + Cl?, with CX1X2?? = CH2??, CHF??, CHCl??, CHBr??, CHI??, CF2??, CCl2??, CBr2??, and CI2??. The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH2?? should be a strongest base among the anion‐containing species (CX1X2??) and so more favorable nucleophile. (b) Regardless of frontside attacking pathway or backside one, the SN2 reaction starts at an identical precomplex whose formation with no barrier. (c) The back‐SN2 pathway is much more preferred than the front‐SN2 one in terms of the energy gaps [ΔE(front)?ΔE(back)], steric demand, NBO population analysis. Thus, the back‐SN2 reaction was discussed in detail. On the one hand, based on the energy barriers (ΔE and ΔE) analysis, we have strongly affirmed that the stabilization of back attacking transition states (b‐TSs) presents increase in the order: b‐TS‐CI2 < b‐TS‐CBr2 < b‐TS‐CCl2 < b‐TS‐CHI < b‐TS‐CHBr < b‐TS‐CHCl < b‐TS‐CF2 < b‐TS‐CHF < b‐TS‐CH2. On the other hand, depended on discussions of the correlations of ΔE with influence factors (PA, IE, bond order, and ΔE), we have explored how and to what extent they affect the reactions. Moreover, we have predicted that the less size of substitution (α‐atom) required for the gas‐phase reaction with α‐nucleophile is related to the α‐effect and estimated that the reaction with the stronger PA nucleophile, holding the lighter substituted atom, corresponds to the greater exothermicity given out from reactants to products. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012  相似文献   

13.
The formation of ternary nitridometalates from the elements in the case of the systems Li—Cr, V, Mn—N leads to compounds which contain the transition metals in the highest (VV, CrVI) or a comparably high (MnV) oxidation state. In the corresponding calcium and strontium systems, the transition metals show a lower oxidation state (VIII, CrIII, MnIII). Transition metals with intermediate oxidation states (CrV, MnIV) are present in the quaternary (mixed cation) compounds Li4Sr2[CrN6], Li6Ca2[MnN6], and Li6Sr2[MnN6] (R3¯(#148), a = 585.9(3) pm, c = 1908.6(4) pm, Z = 3), as well as in the solid solution series Li6(Ca1—xSrx)2[MnN6].  相似文献   

14.
New oxocarbenium perchlorates, [(C2H5)(4-n)C(CH2OCH2CH2CO+ClO)n, n = 3, 4] were synthesized and used in the preparation of poly (tetrahydrofuran) (PTHF) polyols. The structures of PTHF polyols and corresponding hydrolysis products were determined by 1H-NMR and FTIR. GPC curves showed that the amount of cyclic oligomers was negligible. The polymerization process was followed by gas chromatography. Kinetic studies showed no termination reaction. The mechanism of the polymerization was discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3391–3399, 1999  相似文献   

15.
Fluorospherands (F‐spherands) are highly preorganized hosts composed of fluorobenzene or 4‐methylfluorobenzene units attached to one another at their 2,6‐positions. To understand the intrinsic factors affecting cation complexation, we investigated the complexation behavior between F‐spherands and cations using density functional theory (DFT) at the level of B3LYP/6‐31G**. The F6‐spherand (C6H3F)6, ( 1 ) has a highly preorganized spherical cavity, which can encapsulate Li+ and Na+. Its cavity is not big enough for K+ and NH, which prefer external binding. Plausible conformations were studied for F8‐spherand (C6H3F)8. Conformer of D2d symmetry ( 2b ) is more stable than that of D4d ( 2a ), in agreement with NMR experiments. The cavity size of F8‐spherand is big enough to encapsulate all cations studied. However, the cavity size of 2b is smaller than that of 2a , which resulted in the guest selectivity. Upon complexation, 2b conformation is more stable for Li+ and Na+, while 2a conformation is preferred for larger cations such as K+ and NH. Thus, the ab initio calculations over these highly preorganized fluorospherands give important insights into their host–guest chemistry. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007  相似文献   

16.
The Hartree-Fock instablities of S2N2 are reported and compared with those of S3N and S4N. These unsaturated sulfur nitrogen planar rings are π electron rich and although the symmetry adapted HF solutions are singlet stable at the experimental bond lengths they become unstable with only a very modest increase in bond length. The broken symmetry solutions for S2N3, S3N, and S4N are of planar C2v type with one of the nitrogens stripped of its π electrons, producing a π hole.  相似文献   

17.
Ab initio calculations at the CCSD(T)/6‐311++G(2d,p)//B3LYP/6‐311++G(d,p) level of theory have been carried out for three prototypical rearrangement processes of organosilicon anion systems. The first two are reactions of enolate ions which involve oxygen–silicon bond formation via three‐ and four‐membered states, respectively. The overall reactions are: The ΔG (reaction) values for the two processes are +175 and +51 kJ mol?1, with maximum barriers (to the highest transition state) of +55 and +159 kJ mol?1, respectively. The third studied process is the following: (CH3O)C(?CH2)Si(CH3)2CH → (CH3)2(C2H5)Si? + CH2CO, a process involving an SNi reaction between ‐CH and CH3O‐ followed by silicon–carbon bond cleavage. The reaction is favourable [ΔG(reaction) = ?39 kJ mol?1] with the barrier for the SNi process being 175 kJ mol?1. The previous experimental and the current theoretical data are complementary and in agreement. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

18.
A New Structure Type of Copper Lanthanoide Oxotungstates: CuDy5(WO4)8 Single crystals of the hitherto unknown compound CuDy5(WO4)8 were prepared in closed copper tubes and investigated by X-ray technique. It shows monoclinic symmetry, space group C—C2/c, a = 19.118, b = 5.612, c = 11.518 Å, β = 111.32°, Z = 2. The crystal structure is characterized by [W4O18] groups which are connected to layers. Dy3+ shows one sided capped trigonal prisms and Cu+/Dy3+ with statistical distribution an octahedral oxygen surrounding.  相似文献   

19.
We have determined the dynamic dipole (α1), quadrupole (α2), octupole (α3), and dipole–dipole–quadrupole (B) polarizabilities and the second hyperpolarizability tensor (γ) for the helium atom in its lowest triplet state (23S). We have done so for both real and imaginary frequencies: in the former case, for a range of frequencies (ω) between zero and the first electronic-transition frequency, and in the latter case for a 32-point Gauss–Legendre grid running from zero to ?ω = 20 Eh. We have also determined the dispersion-energy coefficients C6, C8, and C10 for the systems H(12S)? He(23S), He(11S)? He(23S), and He(23S)? He(23S) and the C, C, C, C, and C coefficients for the interaction He(23S)? H2(X1∑). Our values of the higher-order multipolar polarizabilities and of γ for the 23S state of helium are, we believe, the first to be published. © 1993 John Wiley & Sons, Inc.  相似文献   

20.
The rate constants for the reactions of OH radicals with CH3OCF2CF3, CH3OCF2CF2CF3, and CH3OCF(CF3)2 have been measured over the temperature range 250–430 K. Kinetic measurements have been carried out using the flash photolysis, laser photolysis, and discharge flow methods combined respectively with the laser induced fluorescence technique. The influence of impurities in the samples was investigated by using gas‐chromatography. The following Arrhenius expressions were determined: k(CH3OCF2CF3) = (1.90) × 10−12 exp[−(1510 ± 120)/T], k(CH3OCF2CF2CF3) = (2.06) × 10−12 exp[−(1540 ± 80)/T], and k(CH3OCF(CF3)2) = (1.94) × 10−12 exp[−(1450 ± 70)/T] cm3 molecule−1 s−1. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 846–853, 1999  相似文献   

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