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1.
Synthesis and Structure of Lithium Tris(trimethylsilyl)silanide · 1,5 DME Lithium tris(trimethylsilyl)silanide · 1,5 DME 2a synthesized from tetrakis(trimethylsilyl)silane 1 [6] and methyllithium in 1,2-dimethoxyethane , crystallizes in the monoclinic space group P21/c with following dimensions of the unit cell determined at a temperature of measurement of ?120 ± 2°C: a = 1 072.9(3); b = 1 408.3(4); c = 1 775.1(5) pm; β = 107.74(2)°; 4 formula units (Z = 2). An X-ray structure determination (Rw = 0.040) shows the compound to be built up from two [lithium tris(trimethylsilyl)silanide] moieties which are connected via a bridging DME molecule. Two remaining sites of each four-coordinate lithium atom are occupied by a chelating DME ligand. The Li? Si distance of 263 pm is considerably longer than the sum of covalent radii; further characteristic mean bond lengths and angles are: Si? Si 234, Li? O 200, O? C 144, O?O (biß) 264 pm; Si? Si? Si 104°, Li? Si? Si 107° to 126°; O? Li? O (inside the chelate ring) 83°. Unfortunately, di(tert-butyl)bis(trimethylsilyl)silane 17 prepared from di(tert-butyl)dichlorsilane 15 , chlorotrimethylsilane and lithium, does not react with alkyllithium compounds to give the analogous silanide.  相似文献   

2.
Metal Derivatives of Molecular Compounds. VI. Lithium and (Tetrahydrofuran)lithium Cyanotrimethylsilylamide — Syntheses and Structures At different temperatures N,N′-bis(trimethylsilyl)carbodiimide ( 1 ) and lithium methanide react either under addition or substitution. When compound 1 , however, is treated at ?40°C with an equimolar amount of (1,2-dimethoxyethane-O,O′)lithium phosphanide ( 2 ) in 1,2-dimethoxyethane, only exchange of one trimethylsilyl group versus lithium is observed and in addition to phosphane and tris(trimethylsilyl)phosphane a very pure lithium derivative insoluble in n-pentane can be isolated. The vibrational spectra prove the compound to be lithium cyanotrimethylsilylamide ( 3 ). Recrystallization from tetrahydrofuran (+40/+20°C) yields (tetrahydrofuran)lithium cyanotrimethylsilylamide ( 3 ′). As shown by an X-ray structure analysis {C2/c; a = 2 261.1(5); b = 1 106.4(2); c = 1 045.9(2) pm; β = 113.63(1)°; Z = 8 formula units}, compound 3 ′ is polymeric in the solid state. Coordinative Li? N2′ bonds allow a head-to-tail addition of two monomeric units each to give an eight-membered heterocycle with two linear N1? C2≡N2 fragments (N1? C2 126.1; C2≡N2 117.5; N1? Si 171.4; Li? N1 203.2; Li? N2′ 206.1 pm; C2? N1? Li 109.0; N1? Li? N2′ 115.9; N2≡C2? N1 177.2°). Forming planar four-membered Li? N2? Li? N2 rings (Li? N2″″ 198.3 pm; Li′? N2? Li″ 80.3; N2′? Li? N2″″ 99.5°) these heterocycles polymerize to slightly folded tapes.  相似文献   

3.
Metal Derivatives of Molecular Compounds. III. Molecular and Crystal Structure of Lithium bis(trimethylsilyl)phosphide · DME and of Lithium dihydrogenphosphide · DME Lithium bis(trimethylsilyl)phosphide · DME 1 prepared from tris(trimethylsilyl)-phosphine and lithium methanide [2, 4] in 1,2-dimethoxyethane
  • 1 1,2-Dimethoxyethan (DME); Tetrahydrofuran (THF); Bis[2-(dimethylamino)ethyl]methyl-amin (PMDETA).
  • , crystallizes in the orthorhombic space group Pnnn {a = 881.1(9); b = 1308.5(9); c = 1563.4(9) pm at ?120 ± 3°C; Z = 4 formula units}, lithium dihydrogenphosphide · DME 2 [10] prepared from phosphine and lithium- n -butanide in the same solvent, in P2 1 2 1 2 1 {a = 671.8(1); b = 878.6(1); c = 1332.2(2) pm at ?120 ± 3°C; Z = 4 formula units}. X-ray structure determinations (R w = 0.036/0.045) show the bis(trimethylsilyl) derivative 1 to be dimeric with a planar P? Li? P? Li ring (P? Li 256 pm; Li? P? Li 76°; P? Li? P 104°), and the dihydrogenphosphide 2 to be polymeric with a linear Li? P? Li fragment (P? Li 254 to 260 pm; Li? P? Li 177°; P? Li? P 118°). The shortened P? Si distance (221 pm) of compound 1 and the structure of the PH 2 group in 2 are discussed in detail. Lithium obtains its preferred coordination number 4 by a chelation with one molecule of 1,2-dimethoxyethane (Li? O 202 to 204 pm).  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.
    Metal Derivatives of Molecular Compounds. IV Synthesis, Structure, and Reactivity of Lithium [Tris(trimethylsilyl)silyl]tellanide · DME Lithium tris(trimethylsilyl)silanide · 1,5 DME [3] and tellurium react in 1,2-dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide · DME ( 1 ). An X-ray structure determination {-150 · 3·C; P21/c; a = 1346.6(4); b = 1497.0(4); c = 1274.5(3) pm; β = 99.22(2)·; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li? Te? Li? Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li? Te 278 and 284; Si? Te 250; Li? O 200 pm (2X); Te? Li? Te 105°; Li? Te? Li 75°; O? Li? O 84°}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 ± 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane ( 2 ), methyl-[tris(trimethylsilyl)silyl]tellane ( 4 ) and bis[tris(trimethylsilyl)silyl]ditellane ( 5 ) are formed.  相似文献   

    6.
    Metal Derivatives of Molecular Compounds. VIII. catena-Poly[(2,5,8-trioxanonane-O2,O5) lithium-methylphosphanide] — a Compound with a meso-Helix Structure Studies of Fritz et al. [10] showed methylphosphane to be lithiated at ?60°C in 1,2-dimethoxyethane or bis(2-methoxyethyl) ether solution by stoichiometric amounts of lithium n-butanide in n-hexane. After removing the hydrocarbons almost completely by distillation and cooling the solutions to ?60°C again, colourless square crystals of (1,2-dimethoxyethane-O,O′)lithium ( 1 ) and (2,5,8-trioxanonane-O2,O5)lithium methylphosphanide ( 2 ) precipitate. As shown by an X-ray structure determination (monoclinic, P21/n; a = 805.5(1); b = 1820.6(2); c = 851.5(1) pm; β = 116.76(1)° at ?100 ± 3°C; Z = 4 formula units; R = 0.034) complex 2 forms a polymer which has the shape of an up to now scarcely noted meso-helix. Four-coordinated lithium is bound to two phosphorus (P? Li 252.9 and 253.2 pm; P? Li? P 131.8°; Li? P? Li 132.1°) and to two oxygen atoms (Li? O 203.9 and 206.8; O …? O 270.7 pm; O? Li? O 82.5°) of the inherently tridentate 2,5,8-trioxanonane ligand. As compared to the standard value (185 pm) the P? C distance (187.4 pm) is slightly lengthened. Structure determinations of (2,5,8-trioxanonane-O2,O5,O8) lithium 1-(phenylsulfonyl)alkyl compounds published some years ago [26, 27], allow a comparison of molecular parameters characteristic for the twofold or threefold coordinating chelate ligand.  相似文献   

    7.
    Alkylidynephosphanes and -arsanes. I [P ≡ C? S]?[Li(dme)3]+ – Synthesis and Structure O,O′-Diethyl thiocarbonate and bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide dissolved in 1,2-dimethoxyethane, react below 0°C to give ethoxy trimethylsilane and tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide – [P≡C? S]? [Li(dme)3]+ – ( 1a ). Apart from bis(trimethylsilyl)sulfane or carbon oxide sulfide, dark red concentrated solutions of λ3-phosphaalkyne 1 are also obtained from reactions of carbon disulfide with bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide or with the homologous lithoxy-methylidynephosphane ( 2 ) [1]. The ir spectrum shows two absorptions at 1762 and 747 cm?1 characteristic for the P≡C and C? S stretching vibrations. The nmr parameters {δ(31P) ? 121.3; δ(13C) 190.8 ppm; 1JCP 18.2 Hz} resemble much more values of diorganylamino-2λ3-phosphaalkynes than those of bis(1,2-dimethoxyethane-O,O′)lithoxy-methylidyne-phosphane ( 2a ). As found by an X-ray structure analysis (P21/c; a = 1192.6(16); b = 1239.1(19); c = 1414.8(26) pm; β = 105.91(13)° at ?100 ± 3°C; Z = 4 formula units; wR = 0.064) of pale yellow crystals (mp. + 16°C) isolated from the reaction with O,O′-diethyl thiocarbonate, the solid is built up of separate [P≡C? S]? and [Li(dme)3]+ ions. Typical bond lengths and angles are: P≡C 155.5(11); C? S 162.0(11); Li? O 206.4(17) to 220.3(20) pm; P≡C? S 178.9(7)°.  相似文献   

    8.
    Metal Derivatives of Molecular Compounds. VII. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium Disilylphosphanide — Synthesis and Structure Crystalline lithium phosphanides studied so far show a remarkably high diversity of structure types dependent on the ligands at lithium and the substituents at phosphorus. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium disilylphosphanide ( 1 ) discussed here, belongs to the up to now small group of compounds which are ionic in the solid state. It is best prepared from silylphosphane by twofold lithiation with lithium dimethylphosphanide first and subsequent monosilylation with silyl trifluoromethanesulfonate, followed by complexation. As found by X-ray structure determination (wR = 0.038) on crystals obtained from diethyl ether {monoclinic; space group P21/c; a = 897.8(1); b = 1 673.6(2); c = 1 466.8(1) pm; β = 90.73(1)° at ?100 ± 3°C; Z = 4 formula units}, the lithium cation is tetrahedrally coordinated by four nitrogen atoms of two 1,2-bis(dimethylamino)ethane molecules. Characteristic parameters of the disilylphosphanide anion are a shortened average P? Si bond length of 217 pm (standard value 225 pm) and a Si? P? Si angle of 92.3°.  相似文献   

    9.
    Tris(trimethylsilyl)silylamine and the lithiated and silylated Derivatives — X-Ray Structure of the dimeric Lithium Trimethylsilyl-[tris(trimethylsilyl)silyl]amide The ammonolysis of the chlor, brom or trifluormethanesulfonyl tris(trimethylsilyl)silane yields the colorless tris(trimethylsilyl)silylamine, destillable at 51°C and 0.02 Torr. The subsequent lithiation, reaction with chlor trimethylsilane and repeated lithiation lead to the formation of lithium tris(trimethylsilyl)silylamide, trimethylsilyl-[tris(trimethylsilyl)silyl]amine and finally lithium trimethylsilyl-[tris(trimethylsilyl)silyl]amide, which crystallizes in the monoclinic space group P21/n with a = 1 386.7(2); b = 2 040.2(3); c = 1 609.6(2) pm; β = 96.95(1)° and Z = 4 dimeric molecules. The cyclic Li2N2 moiety with Li? N bond distances displays a short transannular Li …? Li contact of 229 pm. The dimeric molecule shows nearly C2-symmetry, so that one lithium atom forms agostic bonds to both the trimethylsilyl groups, the other one to the tris(trimethylsilyl)silyl substituents. However, the 7Li{1H}-NMR spectrum displays a high field shifted singlet at —1.71 ppm. The lithiation of trimethylsilyl-[tris(trimethylsilyl)silyl]amine leads to a high field shift of the 29Si{1H} resonance of about 12 ppm for the Me3SiN group, whereas the parameters of the tris(trimethylsilyl)silyl ligand remain nearly unaffected.  相似文献   

    10.
    Trimethylsilyl Derivatives of Vb Elements. VII. Crystal Structures of Lithium Bis(trimethylsilyl)bismuthide · DME and of Tetrakis(trimethylsilyl)dibismuthane as well as Some Comments on the Crystal Structure of Bis(4-methoxyphenyl)ditellane Colourless lithium bis(trimethylsilyl)bismuthide · DME
  • 1 1,2-Dimethoxyethan (DME); Tetrahydrofuran (THF)
  • 1 and green, metallic lustrous tetrakis(trimethylsilyl)dibismuthane 2 crystallize isotopic to their antimony homologues [1, 2]. As it is shown by crystal structure determinations { 1 : ?90°C; I 4 2d; a = 1017,3(4); c = 3738,0(26) pm; Z = 8; R w = 0,065; 2 : + 20°C; P2 1 /c; a = 680,9(4); b = 1704,8(13); c = 1197,9 (10) pm; β = 119,46(6)°; Z = 2; R w = 0,084} both compounds form chains which in the case of bismuthide 1 are built up as screws of alternating bismuth and lithium atoms; bonding further to two trimethylsilyl groups or to the chelating DME ligand both atoms gain coordination number 4 {Li? Bi 292(3); Bi? Si 263.3(14) pm; Bi? Li? Bi 132(1); Li? Bi? Li 148(1); φ(Li? Bi? Li? Bi) 83°}. In the case of dibismuthane 2 the centrosymmetric molecules are strung, their Bi-Bi groups forming nearly linear zigzag chains with shortened intermolecular contact distances {Bi-Bi 303.5(3); Bi …? Bi 380.4(3); Bi? Si 268 pm; Bi? Bi …? Bi 169; Bi? Bi? Si 97.4(5) and 92.0(5)°}. Structure and properties of 2 are compared with those of similar compounds; the crystal structure of brown, green metallic lustrous bis(4-methoxyphenyl)ditellane 5 already published by Ludlow and McCarthy[3] is reinvestigated with respect to very short intermolecular Te…?Te contacts.  相似文献   

    11.
    Metal Derivatives of Molecular Compounds. V. Synthesis and Structure of Hexakis{lithium-[tris(trimethylsilyl)silyl]tellanide}—Cyclopentane (1/1) . Lithium [tris(trimethylsilyl)silyl]tellanide—DME (1/1) [1 b] prepared from lithium tris(trimethylsilyl)silanide—DME (2/3) [3] and tellurium, reacts with hydrogen chloride in toluene to form [tris(trimethylsilyl)silyl]tellane ( 1 ) [1 b]. Subsequent metalation of this compound with lithium n-butanide gives lithium [tris(trimethylsilyl)silyl]tellanide ( 2 ) free of coordinating solvent. Pale yellow crystals are obtained from cyclopentane solution. An X-ray structure determination {P1 ; a = 1 558.5(7); b = 1 598.4(8); c = 1 643.5(6) pm; α = 117.64(4); β = 91.63(3); γ = 117.19(3)°; Z = 1; R = 0.032} shows them to be the (1/1) packing complex ( 2 ′) of hexakis{lithium-[tris(trimethylsilyl)silyl]tellanide} and disordered cyclopentane molecules —{Li? Te? Si[Si(CH3)3]3}6 · C5H10.  相似文献   

    12.
    Trimethylsilyl Derivatives of Vb-Elements. II. Molecular and Crystal Structure of Tetrakis(trimethylsilyl)diarsine Pale yellow tetrakis(trimethylsilyl)diarsine 1 which is easily obtained from lithium bis(trimethylsilyl)arsenide · 2 tetrahydrofurane (THF) and 1,2-dibromoethane crystallizes in a trigonal, acentric space group. The dimensions of the unit cell determined at ?95 ± 5°C are: a = 974.2(2); c = 2 080.0(4) pm; Z = 3. Considering anomalous dispersion the refinement of structural data in space group P3121 converges at an R-value of 0.060, in its enantiomorph P3221, however, at 0.031. With a dihedral angle Si2′? As′? As? Si1 of ?125.7° the molecule adopts gauche conformation. Both bis(trimethylsilyl)arsino groups are symmetry-related by the crystallographic operation of the diad. Characteristic bond lengths and angles are: As? As 245.8(1); As? Si 236.5(1) and 236.2(2) pm; Si? As? Si 100.90(5); As? As? Si 93.87(3) and 113.63(4)°. The shortest intermolecular As? As distance is found to be 662 pm.  相似文献   

    13.
    Trimethylsilyl Derivatives of Vb-Elements. V. Molecular and Crystal Structure of Lithium Bis(trimethylsilyl)arsenide · DME Lithium bis(trimethylsilyl)arsenide · DME 1 obtained from tris(trimethylsilyl)-arsine and n-butyl or methyl lithium in 1,2-dimethoxyethane crystallizes monoclinic with {a = 1813(3); b = 1327(3); c = 968(1) pm; β = 119.3(1)°; Z = 4} at +20°C. Experimental conditions unfavourable for an X-ray structure determination caused high standard deviations of all structural parameters. The refinements of these values calculated with respect to the centrosymmetric space group C2/m converged at a relatively high R-value of 0.090. In contrast to the homologous antimonide lithium bis(trimethylsilyl)arsenide · DME 1 is found to be dimeric in solution as well as in the solid state. The four-membered ring built up by bis(trimethylsilyl)arsino groups and DME-coordinated lithium atoms in alternating sequence is planar; the carbon atoms statistically occupy positions on both sides of a mirror plane. Characteristic bond lengths and angles are: As? Si 230.7(7); As? Li 259(2); Li? O 205(4) and 215(4) pm; Si? As? Si 103.2(4)°; Li? As? Li 81(1)°; As? Li? As 99(1)° and Li? As? Si 115(1)°.  相似文献   

    14.
    Formation of Organosilicon Compounds. 112. The Influence of Reaction Conditions on the Reaction of (Cl3Si)2CCl2 with Silicon. The Structures of 2,2,3,3,5,5,6,6-Octachloro-1,4-bis(trichlorosilyl)-2,3,5,6-tetrasilabicyclo[2.1.1]-hexane and 1,1,3,4,6,6-Hexakis(trichlorosilyl)hexatetraene While reactions of (Cl3Si)2CCl2 1 with Si(Cu) in a fluid bed at 320°C exclusively yield products by silylation of the CCl2 group in 1 does the reaction in a stirred bed preferrably give rize to chlorosilanes containing C? C double and triple bonds. Compounds 5, 6, 7, 8 and 9 in Tab. 1 belong to the first group, whereas 3 and 4 belong to the second one. The reaction of 1 with elemental copper under dehalogenation at carbon produces 3, 4 and 11 . In the reaction of 1 with CaSi2 no additional Si? C bonds are formed, exclusively chlorosilanes with multiple C? C bonds as 3, 4 and 10 were found besides of SiCl4. The bicyclo[2.1.1]hexane 6 (Tab. 1) crystallizes monoclinically in the space group C2/c (no. 15) with a = 1557.8, b = 857.4, c = 1727.3 pm, β = 104.34° und Z = 4 molecules per unit cell; the hexatetraene 10 (Tab. 1) crystallizes monoclinically in the space group C2/m (no. 12) with a = 1189.6, b = 1433.8, c = 983.5 pm, β = 98.75° pm, and Z = 2 molecules per unit cell. The skeleton of 6 is a system of high bond stress with 2-C2 symmetry. The strongly folded (138.8°) four-membered ring (sum of angles = 344.2°) and the presence of both a Si? Si bond length of 238.2 pm and a Si? Si non-bonding distance of 255.1 pm are remarkable aspects of this feature. The mean bond lengths in the bicyclic compound were found to be d(Si? C) = 190.9 pm and d(Si? C) = 185.1 pm for exo- and endocyclic bonds, respectively. The skeleton of 10 is of the symmetry 2/m-C2h. The six-membered chain is plane. The central C? C single bond length and the mean distance of the cumulated double bonds are 148.6 pm and 130.5 pm, respectively.  相似文献   

    15.
    Silanediyldiphosphinite tBu2Si(OPPh2)2 1 has been synthesised. 1 reacts with the norbornadiene complexes C7H8M(CO)4 (M = Cr, Mo, W) to give six-membered chelate rings of the type cis-M(CO)4[tBu2Si(OPPh2)2] 2–4 . The crystal structures of the chromium and molybdenum complexes cis-Cr(CO)4[tBu2Si(OPPh2)2] 2 and cis-Mo(CO)4[tBu2Si(OPPh2)2] 3 have been determined. Both complexes crystallise in the triclinic system (space group P1 ) with unit cell parameters: ( 2 ) a = 1 093(3) pm, b = 1 477(5) pm and c = 1 542(5) pm; α = 108.4(2)°, b? = 103.87(11)° and b? = 104.57(10)°; U = 2.143(12) nm3; Z = 2; ( 3 ) a = 1 097.8(2) pm, b = 1 483.7(2) pm and c = 1 554.3(2) pm; α = 108.10(1)°, b? = 103.956(6)° and γ = 104.213(7)°; U = 2.1899(6) nm3; Z = 2. Both 2 and 3 consist of discrete, slightly distorted, octahedral monomers in which the six-membered chelate rings are essentially planar. In contrast, the conformations of the chelate rings found in crystal structures of analogous complexes vary from twist-boat to “chaise longue”.  相似文献   

    16.
    Preparation, Crystal Structure, and Properties of KLi2As The novel arsenide KLi2As has been synthesized either from the elements or from mixtures of the binary components Li3As and K3As in sealed Nb ampoules at 823 K and 623 K, respectively. It crystallizes in the space group Pmmn (no. 59) with a = 445.8(9); b = 671.5(11); c = 627.0(12) pm and Z = 2 formula units. The metallic reflecting silvercoloured platelets hydrolize rapidly under wet air. The compound (Pearson code oP8) is isopuntal with BaLi2Si and an intermediate between the Li3N and the Na3As type of structure. Potassium is distorted tetrahedrally coordinated by four As atoms (d(K? As) = 355 and 367 pm), arsenic by four potassium and six lithium atoms (d(As? K) = 355–367 pm; d(As? Li) = 260–265 pm) in form of a sphenocorona. Lithium is threefold coordinated (distorted trigonal planar) by arsenic and this unit is enveloped by a monocapped trigonal prism build by three lithium and four potassium atoms.  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.
    Syntheses and Crystal Structures of the Nitrido‐chloro‐molybdates [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 and [Li(12‐Crown‐4)(NMoCl4)]2 · 2 CH2Cl2 Both the title compounds as well as [Li(12‐crown‐4)2]+MoNCl4 were made from MoNCl3 and the chlorides MgCl2 and LiCl, respectively, in dichloromethane suspensions in the presence of tetrahydrofuran and 12‐crown‐4, respectively. They form orange‐red moisture‐sensitive crystals, which were characterized by their IR spectra and partly by crystal structure analyses. [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 ( 1 ): space group C2/m, Z = 2, lattice dimensions at –50 °C: a = 1736.6(1), b = 1194.8(1), c = 1293.5(2) pm; β = 90.87(1)°; R1 = 0.037. In 1 the magnesium ion is coordinated octahedrally by the oxygen atoms of the four THF molecules and in trans‐position by the nitrogen atoms of the two [N≡MoCl4(THF)] ions. [Li(12‐crown‐4)(NMoCl4)]2 · 2 CH2Cl2 ( 2 ): space group P 1, Z = 1, lattice dimensions at –70 °C: a = 930.4(1), b = 957.9(1), c = 1264.6(1) pm; α = 68.91(1)°, β = 81.38(1)°, γ = 63.84(1)°; R1 = 0.0643. 2 forms a centrosymmetric ion ensemble in the dimeric cation of which, i. e. [Li(12‐crown‐4)]22+, the lithium ions on the one hand are connected to the four oxygen atoms each of the crown ether molecules in a way not yet known; and in addition, each of the lithium ions enters into a intermolecular Li–O bond with neighboring crown ether molecules under formation of a Li2O2 four‐membered ring. The two N≡MoCl4 counterions are loosely coordinated to one oxygen atom each of the crown ether molecules with Mo–O distances of 320.2 pm.  相似文献   

    19.
    Acyl- and Alkylidenephosphines. XXVII. Molecular and Crystal Structure of Methyl-[(N-phenyl, N-trimethylsilyl)thiocarbamoyl]trimethylsilylphosphine . Methyl[(N-phenyl, N-trimethylsilyl)thiocarbamoyl]trimethylsilylphosphine 1a formed via an addition of methylbis(trimethylsilyl)phosphine to phenyl isothiocyanate [1], crystallizes in the monoclinic centrosymmetric space group P21/n with following dimensions of the unit cell determined at a temperature of measurement of ?80±3°C: a=1041.2(4);b=1706.9(12);c=1001.1(6)pm; β=106.41(4)°; Z = 4. An X-ray structure determination (Rw = 0.039) confirms the constitution of the compound as already derived from its nmr spectra. One trimethylsilyl group is bound to the phosphorus atom, whereas the other is connected with the sp2-hybridized nitrogen atom. Characteristic rounded bond lenghts and angles are: P? Si 231, P? CH3 184, P? C(S) 187, C?S 167, N? C(S) 137, and N? Si 181 pm as well as P? C? S 122°, P? C? N 117°, and S? C? N 121°.  相似文献   

    20.
    Alkylidynephosphanes and -arsanes. II. Oxydation of Lithoxy-methylidynephosphane P?C? O? Li with Sulphur Dioxide and Iodine At ?50°C bis(1,2-dimethoxyethane-O,O′)lithoxymethylidynephosphane P?C? O? Li(dme)21,2) ( 1 a ) [2] reacts almost quantitatively with sulphur dioxide or iodine in 1,2-dimethoxyethane solution to give bis(1,2-dimethoxyethane-O,O′)bis(tetrahydrofuran-O)(μ-1,2,4-triphospholo[1,2-a]-1,2,4-triphosphol-1,3,5,7-tetraonato(2?)-O1,O7:O3,O5)dilithium ( 2 a ) and lithium dithionite or iodide respectively. From the reaction with sulphur dioxide the crystalline, pale yellow compound is obtained in 40% yield. The formation of the unusual anionic heterocycle, built up of four PCO units, may be explained by an oxydation of two [P?C? O]? species first, followed by a nucleophilic attack of two other [P?C? O]? anions and coupled ?intramolecular”? cycloaddition reactions. In the 31P{1H} nmr spectrum two phosphorus atoms each of coordination number two and three give rise to two triplets with chemical shift values of 81.4 and 36.9 ppm and a 2J(PP) coupling constant of 31.7 Hz; the 13C{1H} resonances of the [(PCO)4]2? anion come from an ABMM′X spin system, the X part being discussed in detail. An X-ray structure determination {Cmcm; a = 1 277.14(11); b = 1 487.7(2); c = 1 556.94(11) pm at ?100 ± 3°C; Z = 4 molecules; R1 = 0.061; wR2 = 0.150} shows compound 2 a to crystallize as a neutral complex of symmetry mm2. The anionic part of the molecule consists of two anellated 1,2-dihydro-5-oxo-1,2,4-triphosphol-3-olate rings which share the central P? P unit (P1? P1′ 215.3; P1–C1 189.1; C1 P2 178.4; C1 O1 123.9pm; C1? P1? P1′ 98.4; Cl? P1? C1″ 91.2; C1 P2 C1′ 98.7°). Thus compound 2a may be assigned to the group of P? P heterocycles with a butterfly structure [71–75] as well as to the well-known diacylphosphanides taking into account, however, the unusual E,E configuration of both O?C? P?C? O? units. The lithium cations are square pyramidally coordinate (Li? O 193.5 to 209.1 pm), each additionally binding an 1,2-dimethoxyethane and a tetrahydrofuran molecule.  相似文献   

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