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1.
Janet E. Del Bene 《Chemical physics letters》1979,64(2):227-229
Ab initio SCF calculations have been performed to investigate the structural and electronic features of the interactions of H+ and Li+ with the oxygen bases H2CO and OH?. The data indicate that the OH interactions are primarily covalent while the LiO interactions are primarily electrostatic, although the LiO interaction in LiOH has considerable covalent character. 相似文献
2.
《Journal of organometallic chemistry》1986,317(3):267-275
The solid state structure of trimethylsilylmethyllithium has been determined by single crystal X-ray diffraction techniques. The compound crystallizes in the monoclinic system, space group P21/n. Cell dimensions were determined as follows: a 10.931(3), b 18.397(6), c 21.490(8) Å, β 96.0(2)°, V 4298(2) Å3, Z = 4, and a final Rf 5.1% based on 2203 data with σ(I) ≥ 2.5σ(I). The compound is formed by hexameric units, {LiCH2Si(CH3)3}6, with two distinct classes of LiLi distances of 2.46 and 3.18 Å. There are also two LiC distances av 2.20 and 2.27 Å. The LiH distances to the methylene H atoms have been determined and are short varying between 2.0 and 2.3 Å to the closest lithium atom. The structure, including possible LiH interactions, is discussed and compared with the other known hexameric aggregates. 相似文献
3.
Christopher M. Johnson Mark G. Shilton Arthur T. Howe 《Journal of solid state chemistry》1981,37(1):37-43
We have measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data. The conductivities (in ohm?1 m?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li+4H2O, 10?4; Li+, Na+, K+, and NH4+3H2O, 10?4, 10?2, 10?4, and 10?4; H+, Li+, and Na+1.5H2O, 10?2, 10?4, and 10?4; Na+1H2O, 10?5; H+, K+, and NH4+0.5H2O, all 10?5; and H+, Li+, Na+, K+, NH+4, and , 10?5, 10?5, 10?4, 10?5, 10?5, and 10?6. A ring mechanism is proposed to account for the high conductivity found in NaUO2PO4 · 3.1H2O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO2PO4(A ? x)H2O, where x can be between 0 and 0.3. 相似文献
4.
Reed M. Izatt Don W. McBride James J. Christensen Jerald S. Bradshaw Glen A. Clark 《Journal of membrane science》1985,22(1):31-46
Carrier-mediated cation fluxes were determined using a H2OCHC13H2O liquid merebrane system for TlNO3 and for binary mixtures of either TlNO3 or KNO3 with alkali metal ions, alkaline earth metal ions, and Pb2+ (in the case of TlNO3). Both macrocyclic polyether and cryptand ligands were used as carriers. In Tl+Mn+ mixtures, selective transport of Tl+ was found over all cations studied, except in the cases of Ag+ by 2.2 and of Pb2+ by 18C6, DC18C6, ClDKP18C6, and 2.2. Generally, K+ was transported selectively from K+Mn+ mixtures, except in the cases of K+Tl+ mixtures in which Tl+ was transported selectively in all cases. A model relating cation flux to log K(CH3OH) for Mn+—macrocycle interaction and to ion-partitioning between the organic and aqueous phases was successful in rationalizing selective cation transport in most of the systems studied. 相似文献
5.
The molecular geometry of perfluoro(methyloxirane) has been studied using gas-phase electron diffraction data, effective least-squares refinement of the structure being achieved with the aid of constraints to limit the number of variable parameters. With the CCF3 bond constrained to be 0.078 Å longer than the ring CC, the refined bond- length values CF (av.) = 1.323(2), CO (av.) = 1.410(8), and CC (ring) = 1.467(7) Å (g values, with e.s.d. in parentheses) were obtained; the angles between ring bonds and substituent CF bonds were CCF (av.) 121(1) and OCF (av.) 114(1)o, the corresponding parameters involving the bulkier CCF3 fragment being larger by 3o in each case [∠CCCF3 124(1)o∠OCCF3 117(2)o]. The remaining refined parameters were ∠CCF(of CF3) = 110.6(4)o and τ , a torsion angle defining the orientation of the CF bonds of the CF3 group with respect to ring bonds, = 29(2)o. Dependent bond angles possessed the values 62.7 (COC), 58.7 [OCC (ring)], 108.3 [FCF (CF3 group)], 114 [FCF (ring CF2)], and 111o (FCCF3). 相似文献
6.
Characteristic fast atom bombardment (FAB) mass spectra (8 keV, argon, glycerol matrix) have been obtained for an isostructural series of organometallic cations of the form cis,trans[(diars)Fe(CO)2(C(O)Me)L]+ Bf4 (L = phosphorus donor). The fast atom bombardment mass spectra (FABMS) obtained show relatively abundant fragments corresponding to the cationic portion of the complex [C+]. Extensive fragmentation also occurs via successive CO loss, phosphorus donor ligand cleavage, and ligand decomposition. Evidence for a rearrangement fragmentation corresponding to the process [Fe(C(O)Me)]+ → [FeMe]+ + CO is presented. 相似文献
7.
《Journal of organometallic chemistry》2002,641(1-2):195-202
Addition of BH3·thf to 1-alkylimidazoles (alkyl=methyl, butyl) and 1-methylbenzimidazole leads to BH3 adducts, which are deprotonated by BuLi to yield the organolithium compounds (L)Li+(1b–d)−. In the solid state (thf)Li+1b− is dimeric. The acyl–iron complexes (thf)3Li+(3b,d)− are formed from (thf)Li+(1b,d)− and Fe(CO)5. (L)Li+(1a–c)− react with [CpFe(CO)2X], however, the only complex obtained is [CpFe(CO)21a] (5a). The analogous reaction of (L)Li+1a− with the pentadienyl complex [(C7H11)Fe(CO)2Br] yields the corresponding iron compound 6a. Their compositions follow from spectroscopic data. Treatment of Cp2TiCl with (L)Li+1a− leads to [Cp2Ti1a] (7a), which could not be oxidized with PbCl2 to give the corresponding Ti(IV) complex. The compounds [Li(py)4]+9a− and [Li(L)4]+(10b–d)− are obtained when (L)Li+1− are reacted with VCl3 and ScCl3. The X-ray structure analysis of the vanadium complex reveals a distorted tetrahedron of the anion [V(1a)4]− with two smaller and four larger CVC angles. The scandium compound [Li(dme)2+10c−] has a different structure: the distorted tetrahedron of the anion [Sc(1c)4]− contains two larger (140.2 and 142.9°) and four smaller CScC angles (93.9–98.7°). This arrangement allows the formation of four bridging BHSc 3c,2e bonds to give an eight-fold coordination. The anion 10c− is formally a 16e complex. 相似文献
8.
9.
《Journal of organometallic chemistry》1987,326(2):151-158
The structure of 2.8 M MgI2 in diethyl ether solution and that of 1.7 M MgI2 in tetrahydrofuran solution have been determined by large angle X-ray scattering measurements. The measurement on the diethyl ether solution was performed at 44°C, on a phase crystallizing at approximately 30°C. In diethyl ether a dimeric structure is found, arranged in a square-planar fashion. The bond lengths are: MgI 2.652(2), II (diagonal) 3.75(2) and II (linear) 5.30 Å. Three diethyl ether molecules are probably coordinated to each magnesium to complete an octahedral arrangement. In tetrahydrofuran the ion MgI+ from a dissociated complex predominates. In the MgI2 complex a tetrahedral arrangement is found. In both the MgI+ and MgI2 complexes the MgI distance is 2.56(2) Å. In the MgI2 complex the II distance is 4.44(4) Å. In both solutions the MgO and MgC distances were kept fixed at 2.10 and 3.48 Å, respectively. The solubility of MgI2 in diethyl ether has been shown to be strongly dependent on the water content of the ether; 0.2 M was the highest concentration obtained in anhydrous diethyl ether. 相似文献
10.
The influence of small monovalent metal ions on hydrogen bonds of the OH…N type is studied with the example Li+/H2ONH3. The net stabilization effect is discussed and compared with the OH…O system. The applicability of the semi-empirical CNDO/2 method and ab initio calculations with extended and minimal basis sets is investigated. 相似文献
11.
《Tetrahedron letters》1986,27(1):33-36
The gas phase reactivity of first row transition metal cations with 2-methylpropane was investigated using a triple quadrupole mass spectrometer. This reactivity is very variable depending on the nature of the metal : Ti+ and V+ give mainly the multiple collision product M(C8H14)+ whereas Cr+, Mn+, Cu+ and Zn+ (reported to be unreactive under other conditions) aaa I or 2 C4H10 units ; Fe+, Co+, Ni+ cleave CH and CC bonds of 2-methylpropane and react further. 相似文献
12.
Hachizo Muto Kazumi Toriyama Keichi Nunome Machio Iwasaki 《Chemical physics letters》1984,105(6):592-597
A 4 K matrix ESR study shows that the molecular radical cations of isopropyl formate and acetate, produced radiolytically in halocarbon matrices at 4.2 K, undergo spontaneous rearrangement due to a selective intramolecular hydrogen shift from the tertiary CH bond in the isopropyl group to the carbonyl oxygen atom giving RC+(OH)OC(CH3)2, where R = H or CH3. The radical cation of tert-butyl acetate undergoes further fragmentation at the ester CO bond following a similar rearrangement to give an isobutene radical cation in CFCl3. 相似文献
13.
β-ketonitriles R1COCH2CN and R1COCH(R2)CN are respectively prepared from (CH3)3SiOCOCHLiCN or R2CHLiCN by acylation reaction with mixed anhydrides RCOOCO2Et. 相似文献
14.
Roland A. Bougon Karl O. Christe William W. Wilson 《Journal of fluorine chemistry》1985,30(2):237-239
Evidence is presented for the existence of (O2+)2MF62?(M=Ni,Mn) salts. These salts are marginally stable up to about 10°C and are characterized by an OO stretching frequency of about 1805 cm?1. 相似文献
15.
Cubic, disordered phases of the compounds MSbO3 (M = Li, Na, K, Rb, Tl, and Ag) have been investigated. KSbO3 is readily synthesized in the disordered, cubic structure at high pressure, and the other isomorphic compounds were obtained by ion exchange. The structures of NaSbO3 and AgSbO3, which have space group Im3, were solved by X-ray single-crystal analysis. The structures contain an essentially rigid SbO3 subarray consisting of pairs of edge-shared octahedra sharing common corners. Within this subarray, face-shared octahedra form 〈111〉 tunnels that intersect at the origin and body center of the unit cell, and the M+ ions are randomly distributed over two positions within these tunnels. Ordered, cubic phases have the primitive-cubic space group Pn3. The two M positions are different for Na+ and for Ag+ ions. At one of the Ag+-ion positions, the AgO bond length is only 2.26 Å, consistent with the gray-black color of AgSbO3. Deformation of the 4d10 Ag+-ion core by 4d-5s hybridization appears to be induced by AgO covalent bonding. This conclusion is compatible with the observation that ion exchange is reversible for all compounds but AgSbO3. Several properties of these compounds are compared with the super ionic conductors M2O·11Al2O3 β-alumina. 相似文献
16.
Solid complexes of boron decachloro-o-carborane and boron decachloro-m-carborane (B10Cl10C2H2) with some oxygen and nitrogen bases have been investigated by infrared and Raman spectroscopy. Complexes containing CH · · O hydrogen bonds are characterized by a relative CH stretching frequency shift up to 12% and a halfwidth of the νCH band up to 220 cm?1. CH · · N hydrogen bonds, with trimethylamine for example, are stronger with a relative shift of about 18% and of about 500 cm?1. Triethylamine complexes, however, form a NH+ · · C? proton transfer hydrogen bond while pyridine can give either CH · · N or C? · · +HN hydrogen-bonded adducts depending on the solvent and temperature. The CH · · N?c? · · +HN equilibrium appears to be shifted towards ion-pair formation at considerably smaller enthalpy values compared to the OH · · N?O? · · +HN system. CH and NH stretching frequencies are correlated with the acidity of the donor and the basicity of acceptor molecules. 相似文献
17.
C. Broquet 《Tetrahedron》1973,29(22):3595-3598
The enolate ylide Ph3P+C?C(Ph)O?Li+ obtained by the reaction of HMPT-Li with the benzoylmethylenetriphenylphosphorane Ph3PCHCOPh reacts with aliphatic ketones, in contrast to its precursor. This condensation makes it possible to prepare β,γ-unsaturated ketones, of type RCHC(R′)CH2COPh, instead of the α,β isomer usually obtained in a Wittig reaction. 相似文献
18.
Giovanni Fronza Pierfrancesco Bravo Calimero Ticozzi 《Journal of organometallic chemistry》1978,157(3):299-310
The 13C chemical shifts, the 13C31P coupling constants, and some one-bond 13C1H coupling constants were measured for the title compounds. For the ylides of phosphorus, arsenic and sulfur, the data are consistent with an sp2-hybridized ylidic carbon with a strong, localized negative charge, while for the pyridinium ylide this charge is much more delocalized. in the homologous series of salts the electron-withdrawing ability of the groups studied varies in the order: Ph3P+ < Ph3As+ « Me2S+ « Me2C5H3N+. The differences in the carbonyl chemical shift between the ylides and the corresponding salts are a measure of the resonance stabilization of the negative charge in the form X+CCO?; this stabilization varies with the groups studied in the order: Ph3P+ < Ph3As+ ≈ Me2S+ « Me2C5H3N+. The ylide—palladium(II) complexes contain a bond between the ylidic carbon and the metal: the ylidic carbon is shifted upfield in the complex with respect to the free ligand, while the adjacent carbonyl is shifted strongly downfield. These data suggest that the PdC(1) bond is strongly polarized with a high electron density on the C(1) atom which cannot be delocalized through resonance as in the free ligands. 相似文献
19.
In this study, two complementary approaches, affinity capillary electrophoresis (ACE) and quantum mechanical density functional theory (DFT) calculations, have been employed for quantitative characterization and structure elucidation of the complex between hexaarylbenzene (HAB)‐based receptor R and lithium ion Li+. First, by means of ACE, the apparent binding constant of Li R + complex (K) in methanol was determined from the dependence of the effective electrophoretic mobilities of Li R + complex on the concentration of lithium ions in the 25 mM Tris/50 mM chloroacetate background electrolyte (BGE) using non‐linear regression analysis. Prior to regression analysis, the effective electrophoretic mobilities of the Li R + complex were corrected to reference temperature 25°C and constant ionic strength 25 mM. The apparent binding constant of the Li R + complex in the above methanolic BGE was evaluated as logK = 1.15±0.09. Second, the most probable structures of nonhydrated Li R + and hydrated Li R +·3H2O complexes were derived by DFT calculations. The optimized structure of the hydrated Li R +·3H2O complex was found to be more realistic than the nonhydrated Li R + complex because of the considerably higher binding energy of Li R +·3H2O complex (500.4 kJ/mol) as compared with Li R + complex (427.5 kJ/mol). 相似文献
20.
Prof. Dr. Werner Uhl Christian Rösener Marcus Layh Alexander Hepp 《无机化学与普通化学杂志》2012,638(11):1746-1754
We have investigated the coordination of alkanide and alkynide anions to the coordinatively unsaturated aluminium atoms of the methylene‐bridged dialuminium compound R2Al‐CH2‐AlR2 [ 1 , R = CH(SiMe3)2]. Treatment of 1 with the corresponding lithium derivatives in the presence of a small excess of TMEN (TMEN = tetramethylethylenediamine) yielded mono‐adducts [M]+[R2Al‐CH2‐AlR2R']– [ 2a , M = Li(TMEN)2, R' = Me; 2b , M = Li(TMEN)2, R' = n‐Bu; 3a , M = Li(TMEN)2, R' = C≡C‐SiMe3; 3b , M = Li(TMEN)2, R' = C≡C‐t‐Bu; 3d , M = Li(DME)3, R' = C≡C‐Ph; 3e , M = Li(TMEN)2, R' = C≡C‐PPh2)] and bis‐adducts [Li(TMEN)2]+[LiCH2(AlR2R')2]– [ 4a , R' = C≡C‐CH2‐NEt2; 4b , R' = C≡C‐t‐Bu]. In the solid state the mono‐adducts have clearly separated coordinatively saturated (coordination number four) and unsaturated aluminium atoms (coordination number three). In solution the groups R' show a fast exchange between both aluminium atoms as evident from the room temperature NMR spectra that showed in most cases equivalent CH(SiMe3)2 groups despite different coordination spheres of the metal atoms. Only 2b gave the expected splitting of resonances at ambient temperature, while cooling was required to prevent the dynamic process for 3a . The dialkynide 4a has a unique molecular structure with one of the lithium cations bonded to the α‐carbon atoms of the alkynido ligands and to the carbon atom of the methylene bridge which is five‐coordinate with a distorted trigonal bipyramidal coordination sphere. 相似文献