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1.
The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph3P−C−CN]M ( 1-M ; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium ( 1-Na ) and potassium ( 1-K ) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η2-coordination mode to the two central carbon atoms. The formation of the yldiide was accompanied by structural changes leading to shorter C−C and longer C−N bonds. This could be attributed to the delocalization of the free electron pairs at the carbon atom into the antibonding orbitals of the CN moiety, which was confirmed by IR spectroscopy and computational studies. Detailed density functional theory calculations show that the changes in the structure and the bonding situation were most pronounced in the lithium compounds due to the higher covalency.  相似文献   

2.
α-Metallated ylides have revealed themselves to be versatile reagents for the introduction of ylide groups. Herein, we report the synthesis of the thiophosphinoyl and piperidyl (Pip) substituted α-metallated ylide [Ph2(Pip)P=C−P(S)Ph2]M (M=Li, Na, K) through a four-step synthetic procedure starting from diphenylmethylphosphine sulfide. Metallation of the ylide intermediate was successfully accomplished with different alkali metal bases delivering the lithium, sodium and potassium salts, the latter isolable in high yields. Structure analyses of the lithium and potassium compounds in the solid state with and without crown ether revealed different aggregates (monomer, dimer and hexamer) with the metals coordinated by the thiophosphoryl moiety and ylidic carbon atom. Although the piperidyl group does not coordinate to the metal, it significantly contributes to the stability of the yldiide by charge delocalization through negative hyperconjugation.  相似文献   

3.
New Alkali Metal Coordinations by Chelating Siloxazane Units within Molecules of the General Formula [X–N–SiMe2–O–SiMe2–N–X]2M4 New solvent free alkali metal amides with Si–O–Si bridges of the general formula [X–N–SiMe2–O–SiMe2–N–X]2M4 (X = tBu ( 1 ), SiMe3 ( 2 ), SiMe2tBu ( 3 ) with M = Li; X = tBu ( 4 ), SiMe3 ( 5 ) with M = Na; X = tBu mit M = K, Li ( 6 )) have been synthesised and characterised by spectroscopic means. X‐ray structure analyses of the six metal derivatives reveal a common structural principle: the four metal atoms within the molecules are incorporated between two molecular halfs and form the bonding links between the two parts. The central molecular skeleton of the molecular halfs consists of a zig‐zag chain N–Si–O–Si–N. This chain is connected to the second one either ideally or approximately by S4 (4) symmetry. The point symmetries within the crystal are either S4 (4) (compounds 2 and 4 ), C2 (2) (compound 6 ), and C1 (1) (compounds 3 and 5 ). Compound 1 is special in different aspects: the molecule has the high crystallographic point symmetry D2d (4m2) and the lithium atoms occupy split atom positions (in a similar way as in compound 2 ). The high symmetry of 1 as well as the split atom positions of the lithium atoms are a consequence of dynamics within the crystal.  相似文献   

4.
Metal Derivatives of Molecular Compounds. IX. Bis(1,2-dimethoxyethane- O,O′ )lithium Phosphanide, Arsanide, and Chloride – Three New Representatives of the Bis(1,2-dimethoxyethane- O,O′ )lithium Bromide Type Experiments to obtain thermally unstable lithium silylphosphanide at –60 °C from a 1,2-dimethoxyethane solution resulted in the isolation of its dismutation product bis(1,2-dimethoxyethane-O,O′)lithium phosphanide ( 1 ). The homologous arsanide 2 precipitated after a frozen solution of arsane in the same solvent had been treated with lithium n-butanide at –78 °C. Unexpectedly, too, the analogous chloride 3 and bromide 4 were formed in reactions of 1-chloro-2,2-bis(trimethylsilyl)-1λ3-phosphaethene with (1,2-dimethoxyethane-O,O′)lithium bis(trimethylsilyl)stibanide and of lithium 1,2,3,4,5-pentaphenyl-2,3-dihydro-1λ3-phosphol-3-ide with ω-bromostyrene, respectively. The monomeric complexes 1 {–100 ± 3 °C; a = 1391.1(4); b = 809.8(2); c = 1249.1(3) pm; β = 102.84(2)°}, 2 {–100 ± 3 °C; a = 1398.3(4); b = 819.8(3); c = 1258.5(4) pm; β = 103.35(2)°} and 3 {–100 ± 3 °C; a = 1308.4(2); b = 788.2(1); c = 1195.6(1) pm; β = 95.35(1)°} crystallize in the monoclinic space group C2/c with four solvated ion pairs in the unit cell; they are isotypic with bis(1,2-dimethoxyethane-O,O′)lithium bromide ( 4 ) {–73 ± 2 °C; a = 1319.0(2); b = 794.1(1); c = 1214.3(2) pm; β = 96.22(1)°}, already studied by Rogers et al. [13] at room temperature. The neutral complexes show a trigonal bipyramidal configuration of symmetry C2, pnicogenanide or halide anions occupying equatorial sites {Li–P 260.4(4); Li–As 269.8(6); Li–Cl 238.6(7); Li–Br 256.3(10) pm} and the chelate ligands spanning equatorial and axial positions {Li–Oeq 205.4(4) to 207.4(4); Li–Oax 208.9(3) to 215.5(2) pm}. The coordination within the (dme)2Li fragment, the Li–X distances (X = P, As, Cl, Br), the structure of the chelate rings, and the packing of the neutral complexes are discussed in detail.  相似文献   

5.
Dinuclear low-valent compounds of the heavy main group elements are rare species owing to their intrinsic reactivity. However, they represent desirable target molecules due to their unusual bonding situations as well as applications in bond activations and materials synthesis. The isolation of such compounds usually requires the use of substituents that provide sufficient stability and synthetic access. Herein, we report on the use of strongly donating ylide-substituents to access low-valent dinuclear group 14 compounds. The ylides not only impart steric and electronic stabilization, but also allow facile synthesis via transfer of an ylide from tetrylene precursors of type RY2E to ECl2 (E=Ge, Sn; RY=TolSO2(PR3)C with R=Ph, Cy). This method allowed the isolation of dinuclear complexes amongst a germanium analogue of a vinyl cation, [(PhY)2GeGe(PhY)]+ with an electronic structure best described as a germylene-stabilized GeII cation and a ylide(chloro)digermene [CyY(Cl)GeGe(Cl)CyY] with an unusually unsymmetrical structure.  相似文献   

6.
The Cu‐catalyzed intramolecular CH insertion of phenyliodonium ylide 1b was investigated at 0° in the presence of several chiral ligands. Enantioselectivities varied in the range 38–72%, and were higher than those resulting from reaction of the diazo compound 1c at 65°. The intramolecular insertion of the enantiomerically pure methyl diazoacetate (R)‐ 20 and of the corresponding phenyliodonium ylide (R)‐ 21 proceeded to (R)‐ 23 with retention of configuration with [Cu(hfa)2] (hfa=hexafluoroacetylacetone=1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione) and [Rh2(OAc)4]. These results are consistent with a carbenoid mechanism for the Cu‐catalyzed insertion with phenyliodonium ylides. However, the insertion of the perfluorosulfonated phenyliodonium ylide (R)‐ 29 afforded with [Cu(hfa)2] as well as with [Rh2(OAc)4] the cyclopentanone derivative 30 as a cis/trans mixture with only 56–67% enantiomeric excess.  相似文献   

7.
Heteronuclear alcoholate complexes [M{Al(OiPr)4}2(bipy)] ( 2-M , M = Fe, Co, Ni, Cu, Zn) and [M{Al(OcHex)4}2(bipy)] ( 3-M , M = Fe, Co, Ni, Zn) are formed by adduct formation of [M{Al(OiPr)4}2] ( 1-M , M = Fe, Co, Ni, Cu, Zn) with 2,2'-bipyridine and transesterification reaction with cHexOAc. According to crystal structure analyses, in 2-M and 3-M the central transition metal ion M2+ is coordinated by two chelating Al(OR)4 moieties and one bipyridine ligand in an octahedral arrangement. Treating 1-Cu with 2,2'-bipyridine leads to a reduction process, whereat the intermediate [Cu{Al(OiPr)4}(bipy)2][Al(OiPr)4] ( 4 ) could be structurally characterized. During conversion of the iso-propanolate ligands in 1-Cu to cyclohexanolate ligands, Cu2+ is reduced to Cu+ forming [Cu{Al(OcHex)4}(py)2] ( 5 ). UV/Vis-spectra and results of thermolysis studies by TG/DTA-MS are reported.  相似文献   

8.
Bisylides and methandiides are two unique families of carbon bases that have found a variety of applications in recent years. Metalated ylides (yldiides) are the link between these types of compounds. Yet, only little is known about their properties, reactivities, and particularly their electronic structure. Here, we report the preparation of the metalated ylide [Ph3P‐C‐SO2Tol]? ( 1 ) with different alkali metal counterions. The compounds have been studied by X‐ray diffraction analysis and NMR spectroscopy and the first structures of a sodium and potassium yldiide are presented. The electronic structure of 1 was explored by DFT calculations confirming its relation with other divalent carbon species. Reactivity studies demonstrate the strong nucleophilicity of the yldiide and its capability to act both as a σ‐ and π‐donor.  相似文献   

9.
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   

10.
The intermediacy of metallocarbenes in decomposition reactions of iodonium ylides with [Rh2(OAc)4] was established by comparison with reactions of the corresponding diazo compounds. The sensitivity of the RhII-catalyzed intermolecular cyclopropane formation from substituted styrenes and bis(methoxycarbonyl)(phenyliodono)methanide ( 1a ) or dimethyl diazomalonate ( 1b ) is identical. The Hammett plot (with σ+) has a slope of ?0.47. Iodonium ylides and diazo compounds afford the same products in [Rh2(OAc)4]-catalyzed cyclopropane formations, cycloadditions, and intramolecular CH insertions, and exhibit the identical selectivity in intramolecular competitions for cyclopropane formation and insertion. The intramolecular CH insertion of the ylide 20c , when carried out in the presence of a chiral catalyst ([Rh2{(?)-(S)-ptpa}4]), results in formation of 21a having an ee of 67%, identical to the ee obtained with the diazo compound 20b .  相似文献   

11.
The reaction of MCl4(thf)2 (M = Zr, Hf) with 1,4-dilitiobutane in diethyl ether at –25 °C or at 0 °C with a molar ratio of 1 : 3 yields the homoleptic “ate” complexes [(thf)4Li] [{(thf)Li}M(C4H8)3] 1 - Zr (M = Zr) and 1 - Hf (M = Hf). The crystalline compounds form ion lattices with solvent-separated [(thf)4Li]+ cations and [{(thf)Li}M(C4H8)3] anions. The NMR spectra at –20 °C show magnetic equivalence of the M–CH2 and of the β-CH2 groups of the butane-1,4-diide ligands on the NMR time scale. Analogous reactions of MCl4(thf)2 with 1,4-dilithiobutane with a molar ratio of 1 : 2 proceed unclear. However, single crystals of [Li(thf)4] [HfCl5(thf)] ( 2 ) can be isolated with the hafnium atom in a distorted octahedral coordination sphere of five chloro and one thf ligand. NMR spectra allow to elucidate the time-dependent degradation of 1-Hf and 1-Zr in THF and toluene at 25 °C via THF cleavage. Addition of tmeda to a solution of 1-Zr allows the isolation of intermediately formed [{(tmeda)Li}2Zr(nBu)2(C4H8)2] ( 3 ).  相似文献   

12.
Two new aminophosphines – furfuryl‐(N‐dicyclohexylphosphino)amine, [Cy2PNHCH2–C4H3O] ( 1 ) and thiophene‐(N‐dicyclohexylphosphino)amine, [Cy2PNHCH2–C4H3S] ( 2 ) – were prepared by the reaction of chlorodicyclohexylphosphine with furfurylamine and thiophene‐2‐methylamine. Reaction of the aminophosphines with [Ru(η6p‐cymene)(μ‐Cl)Cl]2 or [Ru(η6‐benzene)(μ‐Cl)Cl]2 gave corresponding complexes [Ru(Cy2PNHCH2–C4H3O)(η6p‐cymene)Cl2] ( 1a ), [Ru(Cy2PNHCH2–C4H3O)(η6‐benzene)Cl2] ( 1b ), [Ru(Cy2PNHCH2–C4H3S)(η6p‐cymene)Cl2] ( 2a ) and [Ru(Cy2PNHCH2–C4H3S)(η6‐benzene)Cl2] ( 2b ), respectively, which are suitable catalyst precursors for the transfer hydrogenation of ketones. In particular, [Ru(Cy2PNHCH2–C4H3S)(η6‐benzene)Cl2] acts as a good catalyst, giving the corresponding alcohols in 98–99% yield in 30 min at 82 °C (up to time of flight ≤ 588 h?1). Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
Density, Conductivity, and Electrolysis of Liquid Phases in Nonaqueous Systems of the Type MCl/AlCl3/SO2 (M = Li, Na) The temperature dependence of the density and specific conductivity was determined at liquid phases of the composition MAlCl4 · nSO2 + mAlCl3 (M = Li, n = 3–5.5, m = 0.266; M = Na, n = 1.36–4.56, m = 0.01–0.1). The investigated range was between ?30°C and +45°C. For different compositions it was limited by the liquidus point and by the point, where the SO2-equilibrium pressure surpassed 1 bar. The densities are between 1.63 and 1.76 g/cm3, the specific conductivities between 0.03 and 0.07 Ω?1 · cm?1. In diluted solutions below ?10°C NaAlCl4 behaves as a strong electrolyte in which dissociation in Na+ and AlCl4?is prevailing. By electrolysis of the liquid phases at room temperature reversible galvanic cells of the type M/MAlCl4 · nSO2/Cl2, C(M = Li, Na) are generated, which have an open circuit potential between 4.12 and 4.18 volts. The alkali metal deposits are stable in contact with the electrolyte up to 60°C in the case of lithium and 35°C with sodium.  相似文献   

14.
The mechanism of the dirhodium tetracarboxylate-catalyzed O-H insertion reaction of diazomethane and methyl diazoacetate with H2O has been studied in detail using DFT calculations. The rhodium catalyst and a diazo compound couple to form a rhodiumcarbene complex. Of two reaction pathways of the Rh(II)-carbene complex with H2O, the stepwise pathway is more preferable than the concerted one. Formation of a Rh(II) complex-associated oxonium ylide is an exothermal process, and direct decomposition of the ylide gives a very high barrier. The high barriers for the 1,2-H shift of Rh(II) complex-associated oxonium ylides make the ylides become stable intermediates in both reactions, especially for the reactions in solution. Difficulty in formation of a free oxonium ylide supports experimental results, indicating that the Rh(II) complex-catalyzed nucleophilic addition of a diazo compound proceeds via a Rh(II) complex-associated oxonium ylide rather than via a free oxonium ylide.  相似文献   

15.
Li2B6 is formed from the elements as transparent red microcrystalline compound (Li : B = 1 : 3; Mo crucible in closed Nb ampoule; 1723 K; 4 h). Single crystals are grown from a lithium silicide melt with large Li excess at 1923 K. Li2B6 is a semiconductor with electron as well as Li+ ionic conductivity which dominates above 600 K. Microcrystalline samples react with H2O liberating gases and forming a brownish amorphous product, but larger crystals are not very sensitive. – Li2B6 crystallizes tetragonally in a new tP16 structure type which is a variant of the CaB6 structure (a = 5.975 Å, c = 4.189 Å; Z = 2; space group P4/mbm). The [B62–] net of the polymeric octahedro-anion is slightly distorted to give space for the insertion of a (32434) net of the Li+ cations in the cavities (d(B–B)endo = 1.766 Å; d(B–B)exo = 1.720 Å; d(Li–B) = 2.363 Å; d(Li–Li) = 3.094 Å). The incomplete occupancy of the Li position (80%) and the electron density at a further position (20%) indicate the mobility of the Li+ cations.  相似文献   

16.
Cyclability of the Li|Li7La3Zr2O12 interface was tested by voltammetry under externally applied potential difference. It was found that the solid electrolyte synthesized in the study contains a minor amount of an impurity in the form of lithium carbonate. This impurity forms, when brought in contact with metallic lithium, carbon that pierces the whole volume of the ceramic separator and produces a channel for a flow of electrons through the material, which leads to a poor cyclability of the solid electrolyte. A possible way to solve the given problem is via a purposeful replacement of the carbonate in the intergrain space of Li7La3Zr2O12 with another crystalline or glassy plasticizer that possesses an acceptable unipolar lithium conductivity (no less than 10–6 S cm–1) and forms, when brought in contact with metallic lithium, no electrically conducting compound or a compound capable of reversibly intercalating/deintercalating lithium.  相似文献   

17.
Reaction of bromoacylsilane 1 (pink solution) with tBu2MeSiLi (3.5 equiv) in a 4:1 hexane:THF solvent mixture at −78 °C to room temperature yields the solvent separated ion pair (SSIP) of silenyl lithium E‐[(tBuMe2Si)(tBu2MeSi)C=Si(SiMetBu2)] [Li⋅4THF]+ 2 a (green–blue solution). Removal of the solvent and addition of benzene converts 2 a into the corresponding contact ion pair (CIP) 2 b (violet–red solution) with two THF molecules bonded to the lithium atom. The 2 a ⇌ 2 b interconversion is reversible upon THF⇌ benzene solvent change. Both 2 a and 2 b were characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy, and theoretical calculations. The degree of dissociation of the Si−Li bond has a large effect on the visible spectrum (and thus color) and on the silenylic 29Si NMR chemical shift, but a small effect on the molecular structure. This is the first report of the X‐ray molecular structure of both the SSIP and the CIP of any R2E=E′RM species (E=C, Si; E′=C, Si; M=metal).  相似文献   

18.
Reaction of bromoacylsilane 1 (pink solution) with tBu2MeSiLi (3.5 equiv) in a 4:1 hexane:THF solvent mixture at ?78 °C to room temperature yields the solvent separated ion pair (SSIP) of silenyl lithium E‐[(tBuMe2Si)(tBu2MeSi)C=Si(SiMetBu2)]? [Li?4THF]+ 2 a (green–blue solution). Removal of the solvent and addition of benzene converts 2 a into the corresponding contact ion pair (CIP) 2 b (violet–red solution) with two THF molecules bonded to the lithium atom. The 2 a ? 2 b interconversion is reversible upon THF? benzene solvent change. Both 2 a and 2 b were characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy, and theoretical calculations. The degree of dissociation of the Si?Li bond has a large effect on the visible spectrum (and thus color) and on the silenylic 29Si NMR chemical shift, but a small effect on the molecular structure. This is the first report of the X‐ray molecular structure of both the SSIP and the CIP of any R2E=E′RM species (E=C, Si; E′=C, Si; M=metal).  相似文献   

19.
The title compound, dilithium(I) trizinc(II) bis[diphosphate(4−)], is the first quaternary lithium zincopyrophosphate in the Li–Zn–P–O system. It features zigzag chains running along c, which are built up from edge‐sharing [ZnO5] trigonal bipyramids. One of the two independent Zn sites is fully occupied, whereas the other is statistically disordered by Zn2+ and Li+ cations, although the two Zn sites have similar coordination environments. Li+ cations occupy a four‐coordinated independent site with an occupancy factor of 0.5, as well as being disordered on the partially occupied five‐coordinated Zn site with a Zn2+/Li+ ratio of 1:1.  相似文献   

20.
A comparative structural study of LiMPO4 (M = Mn, Fe, Co, Ni) orthophosphates and Li2MPO4F (M = Co, Ni) fluorophosphates obtained by mechanochemically assisted solid-state synthesis is performed using powder XRD, IR, and NMR spectroscopy methods. It is shown that all compounds crystallize in the orthorhombic symmetry (space group Pnma). Lattice parameters decrease on passing from Mn to Ni, which is due to the decrease in the ionic radius of the d metal. According to the IR spectroscopy data, in this series an increase in the covalency of the P–O bond is observed along with a decrease in the covalency of the M–O bond. On passing to fluorophosphates, the symmetry of PO4 tetrahedra increases. 6Li and 31P NMR spectra of all compounds are characterized by the dependence of the contact shift on the nature of metal M and the degree of distortion of the MO6 coordination polyhedron. 6Li MAS NMR line width is noticeably affected by the concentration of structural defects. Unlike orthophosphates with equivalent lithium ions, fluorophosphates contain lithium ions in three different positions.  相似文献   

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