Bis(trimethylsilyl)amide und -methanide des Yttriums — Molekülstrukturen von Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl) methyl]yttriat,solvensfreiem Yttrium-tris[bis(trimethylsilyl)amid] sowie dem Bis(benzonitril)-Komplex

Bis(trimethylsilyl)amides and -methanides of Yttrium — Molecular Structures of Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl)methyl]yttriate, solvent-free Yttrium Tris[bis(trimethylsilyl)amide] as well as the Bis(benzonitrile) Complex The reaction of yttrium(III) chloride with the three-fold molar amount of LiE(SiMe₃)₂ (E = N, CH) yields the corresponding yttrium derivatives. Yttrium tris-[bis(trimethylsilyl)amide] crystallizes in the space group P3 1c with a = 1 636,3(2), c = 849,3(2) pm, Z = 2. The yttrium atom is surrounded trigonal pyramidal by three nitrogen atoms with Y? N-bond lengths of 222 pm. Benzene molecules are incorporated parallel to the c-axes. The compound with E = CH crystallizes as a (Et₂O)₃LiCl-adduct in the monoclinic space group P2₁/n with a = 1 111,8(2), b = 1 865,2(6), c = 2 598,3(9) pm, β = 97,41(3)° and Z = 4. The reaction of yttrium tris[bis(trimethylsilyl)amide] with benzonitrile yields the bis(benzonitrile) complex, which crystallizes in the triclinic space group P1 with a = 1 173,7(2), b = 1 210,3(2), c = 1 912,4(3) pm, α = 94,37(1), β = 103,39(1), γ = 117,24(1)° and Z = 2. The amido ligands are in equatorial, the benzonitrile molecules in axial positions.     

Synthesis and structural characterisation of cobalt(II) and iron(II) chloride complexes containing bis(2-pyridylmethyl)amine and tris(2-pyridylmethyl)amine ligands

Treatment of (2-C₅H₄N)CH_{2 3}N (TPA) with one equivalent of MCl₂ in n-BuOH at elevated temperatures affords the six-coordinate complexes [(TPA)MCl₂] (M = Co (1), Fe (2)) and, in the case of CoCl₂, the five-coordinate chloride salt [(TPA)CoCl]Cl (3). Conversely, addition of an excess of CoCl₂ in the latter reaction leads to [(TPA)CoCl]₂[CoCl₄] (4) as the only isolable product. Interaction of one equivalent of (2-C₅H₄N)CH_{2 2}NH (DPA) and MCl₂ under similar reaction conditions to that described above affords the dimeric species [(fac-DPA)MCl(μ-Cl)]₂ (M = Co (5), Fe (6)), while the bis(ligand) halide salts [(fac-DPA)₂M]Cl₂ (M = Co (7), Fe (8)) are accessible on addition of two equivalents of DPA. In the presence of air, 6 undergoes oxidation to give [ (fac-DPA)FeCl_{2 2}(μ-O)] (9). Single-crystal X-ray diffraction studies are reported for 1, 2 · MeCN, 3, , 7 · 3MeCN, 8 · 3MeCN and 9.     

Multiple bonds between main group elements and transition metals, 155. (Hexamethylphosphoramide) methyl(oxo) bis(η-peroxo)rhenium(VII), the first example of an anhydrous rhenium peroxo complex: crystal structure and catalytic properties

Methyl(oxo)bis(η²-peroxo)rhenium(VII)1, the active species of the system CH₃ReO₃/H₂O₂ in the catalytic oxidation of different organic and organometallic compounds, is stabilized by a water molecule attached to the rhenium center. This water molecule can be removed and substituted by hexamethylphosphoramide (HMPA) to yield (hexamethylphosphoramide)methyl(oxo)bis(η²-peroxo rhenium(VII) (3). The synthesis, crystal structure (X-ray difraction study), and catalytic properties of which compound are reported. Crystal data are as follows: monoclinic, space group P2₁/n, A = 900.76(7) pm, B = 1229.80(11) pm, C = 1318.57(11) pm, β = 90.251(7)°, R_w = 0.034 for 1878 reflections. The catalytic properties of compound 3 in the oxidation of olefins with H₂O₂ are similar to those of 1.     

Preparation of samarimm(ii) sulfide by the reaction of samarium(II) bis[bis(trimethylsilyl)amide] with hydrogen sulfide

X-ray amorphous samarium(II) sulfide was prepared by the reaction of H₂S with samarium(II) bis[bis(trimethylsilyl)amide] (1) in THF at 10^–2 Torr. Compound1 was prepared by two methods: 1) the reaction of SmI₂ with lithium bis(trimethylsilyl)amide and 2) the reaction of samarium naphthalide with bis(trimethylsilyl)amine. SmS was transformed to the polycrystalline state with the lattice parametera = 5.92 Å by annealing at 400–500 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 241–243, February, 1995.     

Recent studies on metal and metalloid bis(trimethylsilyl)methyls and the transformation of the bis(trimethylsilyl)methyl into the azaallyl and β-diketinimato ligands

Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR₂)_m (R = SiMe₃) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR₂)]_∞, [Rb(μ-CHR₂)(PMDETA)]₂, K₄(CHR₂)₄(PMDETA)₂, [Mg(CHR₂)(μ-CHR₂)]_∞, P(CHR₂)₂ (gaseous) and P₂(CHR₂)₄, [Yb(CHR₂)₂(OEt₂)₂] and [{Yb(CR₃)(μ-OEt)(OEt₂)}₂]; earlier information on other M(CHR₂)_m complexes and some of their adducts is tabulated. Treatment of M(CHR₂) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates , and (LL′ = N(R)C(^tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe₃ and Ar = C₆H₃Me₂-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′]⁻, [L′L′]⁻, [LL]⁻, [LL″]⁻, [L″L]⁻, [LL]⁻ and [{N(R)C(^tBu)CH}₂C₆H₄-2]²⁻ are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C(^tBu)C(H)C(Ph)NR, LL = N(R)C(^tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for and , respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides.     

Thallium(I) -bis(trimethylsilyl) amid

The reaction of LiN(SiMe₃)₂ With TlCl in toluene yields the bis(trimethylsilyl)amino derivative of thallium(I) (1). In the gaseous phase and in benzene solution the compound is mainly monomeric, whereas in the solid state the amide 1 consists of cyclic dimers, which are linked to infinite chains by intermolecular Tl Tl contacts.     

(Z)-1-methoxy-4-(diphenylphosphino) but-1-ene-3-yne: A versatile synthon for unsymmetrically substituted (diphenylphosphino) diacetylene derivatives

An efficient synthesis of Ph₂P-C≡C-C≡C-Li, 1, was found, starting from commercially available (Z)-1-methoxybut-1-ene-3-yne and its diphenylphosphino derivative 2. The lithio compound 1 was condensed with electrophiles to give Ph₂P-C≡C-C≡C—Σ (Σ = SiR₃, SnR₃, B(NⁱPr)₂) 3. Compound 2 was easily transformed into the phosphonium salt 6 and the phosphine oxide 7 using MeI and H₂O₂ respectively. Derivatives 3 (Σ = SiMe₃, SnMe₃) are reactive at phosphorus and at the Σ group; complexation with W(CO)₅THF gave the expected derivatives W(CO)₅Ph₂P-C≡C-C≡C—Σ (Σ = SiMe₃, SnMe₃), 10, and in the case of Σ = SnMe₃, coupling reaction between Ph₂P-C≡-C-C≡C-SnMe₃, 3c, and (η⁵-IC₅H₄)Mn(CO)₃ in the presence of PdCl₂(CH₃CN)₂ as a catalyst gave the complex 11, Ph₂P-C≡C-C≡C-(η⁵-C₅H₄)Mn(CO)₃.     

Molekül- und Kristallstruktur des Dimeren Magnesium-bis[bis(trimethylsilyl)amids]

Molecular and Crystal Structure of the dimeric Magnesium bis[bis(trimethylsilyl)-amide] The magnesium bis[bis(trimethylsilyl)amide] crystallizes as a dimeric molecule in the space group C2/c with {a = 1821.0(4); b = 1494.4(4); c = 1859.6(6) pm; β = 121.10(2)°; Z = 4 dimers}. The cyclic planar Mg₂N₂ moiety shows endocyclic NMgN angles of 95.8°. The bond lengths within this ring system to the four-coordinate, bridging nitrogen atoms N^b are 215 pm, whereas the distances between the magnesium atom and the terminal, three-coordinate nitrogen atom N^t display values of approximately 198 pm. These different coordination numbers of the nitrogen atoms affect the NSi bond length (N^tSi 171, N^bSi 177 pm).     

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF

Transamination reactions utilizing the compound mercuric bis(trimethylsilyl)amide, Hg{N(SiMe₃)₂}₂, in tetrahydrofuran (THF), and the metals Na, Mg, Ca, Sr, Ba and Al have been investigated. Thus the THF solvated compounds Na[N(SiMe₃)₂]·THF and M[N(SiMe₃)₂]₂·2THF, M = Mg, Ca, Sr and Ba (1–4), have been prepared. The X-ray crystal structures of 1 and the related manganese compound Mn[N(SiMe₃)₂]₂·2THF (5) are reported. Interaction of the silylamides, 2–4, with a range of crown ethers apparently proceeded with elimination of silylamine, (Me₃Si)₂NH, and novel ring opening of the crown ethers, generating species containing a donor alkoxide ligand with a vinyl ether function, presumably, ---O(CH₂CH₂O)_nCH=CH₂ (n = 3−5). The silylamides 2–4 were also cleanly converted to the corresponding alkoxides (from ¹H NMR data) in reactions with stoichiometric quantities of 3-ethyl-3-pentanol.     

Syntheses, spectroscopic characteristics and thermolytic rearrangements of bis-[(trimethylgermyl)methyl]platinum(II) and bis-[(trimethylstannyl)methyl]platinum(II) complexes

The preparations and spectroscopic characteristics are reported of a series of (trimethylgermyl)methyl- and (trimethylstannyl)methylplatinum(II) complexes with diene and P-donor ancillary ligands, cis-Pt(CH₂GeMe₃)₂L₂ (L = PPh₃ or PPh₂Me; L₂ = dppe or cod) and cis-Pt(CH₂SnMe₃)₂L₂ (L = PPh₃; L₂ =cod). Thermolysis of toluene solutions of cis-Pt(CH₂GeMe₃)₂(PPh₃)₂ leads to cis-Pt(Me)(CH₂GeMe₂CH₂GeMe₃)(PPh₃)₂ via β-alkyl migration, after (non-rate-limiting) phosphine dissociation. Estimated activation parameters (ΔH_{298 K}^‡ = 126 ± 3 kJ mol⁻¹, ΔS^‡ = + 17 ± 7 J mol⁻¹ K⁻¹ and hence Δ_{298 K}^‡ = 121 ± 5 kJ mol⁻¹) suggest that this system is more migration labile than its silicon analogue, primarily as a result of a lower activation enthalpy. While cis-Pt(CH₂GeMe₃)₂(PPh₂Me)₂ reacts similarly but less readily, Pt(CH₂GeMe₃)₂(dppe)₂ is inert at operable temperatures. Thermolysis of Pt(CH₂GeMe₃)₂(cod) generates 1,1,3,3,-tetramethyldi-1,3-germacyclobutane as the major organogermanium product, while from cis-Pt(CH₂SnMe₃)₂(PPh₃)₂, 1,1,3,3-tetramethyldi-1,3-stannacyclobutane predominates. Mechanistic implications are discussed.     

Synthesis, structure and characterization of M---Sn (M=Mo, W) bonded heterobimetallic complexes containing bis(pyrazol-1-yl)methane ligands

The reaction of bis(pyrazol-1-yl)methane tetracarbonylmolybdenum(0) or tungsten(0) complexes with RSnCl₃ (R=Ph, Cl) at room temperature yielded heterobimetallic complexes CH₂(Pz)₂M(CO)₃(Cl)(SnCl₂R) (Pz represents substituted pyrazole; M=Mo or W; R=Ph or Cl) in good yields, which have been characterized by elemental analysis, ¹H NMR and IR spectroscopy. The reaction of bis(3,5-dimethyl-4-halopyrazol-1-yl)methane tetracarbonyl tungsten with PhSnCl₃ did not take place even in refluxing CH₂Cl₂. The electronic and steric characteristics of substituents on the pyrazole ring remarkably influence the structures of the products. The structures of CH₂(3,5-Me₂-4-BrPz)₂W(CO)₃(Cl)(SnCl₃) (8) and CH₂(4-BrPz)₂Mo(CO)₃(μ-Cl)(SnCl₂Ph) (17) (Pz: pyrazole) determined by X-ray crystallography show that no chlorine-bridged W---Sn bond is observed in complex 8, while one chlorine-bridged Mo---Sn bond exists in complex 17. The Sn---M bond length is 2.7438(5) Å in complex 8 (W---Sn) and 2.7559(4) Å in complex 17 (Mo---Sn).     

Reactions of tetrakis(trifluoromethyl) diphosphine and bis(trifluoromethyl) phosphine with ruthenium carbonyl clusters; X-ray structure of tetraruthenium carbonyl cluster derivatives

Reaction of [Ru₃(CO)₁₂ with (CF₃)₂P---P(CF₃)₂ in p-xylene at 140°C yielded the compounds [Ru₄(CO)₁₃{μ-P(CF₃)₂}₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2) and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3). Reaction with [(μ-H)₄Ru₄(CO)₁₂] under similar conditions yielded [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). All four compounds have been characterised by X-ray crystallography. The fluxional behaviour of the hydrides in 4 has also been studied by variable-temperature NMR spectroscopy. Compounds 1, 2 and 4 were also obtained from the reactions of Ru₃(CO)₁₂ with (CF₃)₂PH in dichloromethane at 80°C.     

New synthesis of bis(disiloxanyl)-m-carboranes

Four bis（disiloxanyl）-m-carboranes(（RSiMe2OSiMe₂）₂-m-C₂B₁₀H₁₀,R = H,vinyl,ethynyl,allyl) were synthesized from the reaction of bis（hydroxydimethylsilyl）-m-carborane and disilazanes,and characterized by infrared spectra（IR）,nuclear magnetic resonance（NMR） and mass spectrometry（MS）.     

双(取代水杨醛)缩卡巴肼正丁基锡配合物的合成、结构及除草活性

在微波甲醇溶剂热中,正丁基三氯化锡(n-BuSnCl₃)与双[4-二乙氨基或(3,5-二叔丁基)取代水杨醛]缩卡巴肼和缩硫代卡巴肼配体反应,合成双(取代水杨醛)缩卡巴肼和缩硫代卡巴肼丁基锡配合物,( n-BuSn) ₂CI₃(OH₂)[(2-OH,R)PhCH=NNH]₂CX[R:4-NEt₂(4-二乙氨基),X:O(A1);R:4-NEt₂,X:S(A2);R:3,5-(t-Bu)₂,X:O(A3);R:3,5-(t-Bu)₂,X:S(A4)],经元素分析、IR、¹H 和 ¹³C NMR表征,X射线衍射获得的配合物A2的晶体结构表明,化合物A2是具有六配位畸形八面体构型的双锡核配合物。 配体及其丁基锡配合物均对马齿苋、刺苋、四九菜心、苋菜和决明子靶标植物具有生长抑制作用,且配合物A1和A2具有较广谱、配合物A3和A4具有选择性生长抑制作用,可作为杂草生长抑制候选物研究。     

Novel perfluoroalkenylphosphonates and iodoperfluoroalkenes from 3,3 -bis (trifluoromethyl) -1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene

The reaction of 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene with tris(trimethylsilyl)phosphite gave fluorotrimethylsilane and the respective (Z)-alkenylbis(trimethylsilyl)phosphonates. In one case hydrolysis afforded the free phosphonic acid (CF₃)₃CCF = CFP(O) (OH)₂. Using tri-n-butylphosphine and boron trifluoride etherate, 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene were converted into the corresponding phosphonium tetrafluoroborates, which when reacted further with iodine in the presence of Na₂CO₃ gave the iodo derivatives (CF₃)₃CCF = CFI and C₄F₉OCF = CFI.     

Strontium- und Barium-bis[N,N′ -bis(trimethylsilyl)benzamidinate] aus der Additionsreaktion der Erdalkalimetall-bis[bis(trimethylsilyl)amide] mit Benzonitril

Strontium and Barium Bis[N,N′-bis(trimethylsilyl)benzamidinates] from the Addition Reaction of the Alkaline Earth Metal Bis[bis(trimethylsilyl)amides] and Benzonitrile The reaction of strontium bis[bis trimethylsilyl)amide] with benzonitrile yields strontium bis[N,N′- bis(trimethylsilyl)benzamidinate] · 2THF, which crystallizes in the orthorhombic space group Pbcn (a = 1845.4(3); b = 131 1,3(2); c = 1838,(3) pm; Z = 4). During the similar reaction of barium bis[bis(trimethylsilyl)amide] with benzonitrile the benzonitrile adduct barium bis[N,N′-bis(trimethylsilyl)benzamidinate] · 2 THF · benzonitrile is formed. After the addition of diphenylacetylene to the strontium di(benzamidinate) in diglyme a clathrate of the composition strontium bis[N,N′-bis(trimethylsilyl)benzamidinate] · diglyme · diphenylacetylene could be isolated; the spectroscopic data as well as the X-ray structure (monoclinic, C2/c, a = 1492.2(2); b = 1539.1(2); c = 2337.8(3)pm; Z = 4) confirm the isolated appearance of the acetylene molecule without interaction to the metal center in solution and in the solid state, respectively.     

Synthesis and X-ray crystal structures of amine bis(phenolate) lanthanide complexes containing alkali metal cation

Three lanthanide “ate” complexes L₂YbM(THF)_n supported by amine bis(phenolate) ligand [L=Me₂NCH₂CH₂N{CH₂-(2-O-C₆H₂-Bu^t₂-2,4)}₂; M=Li, n=2 (1); M=Na, n=2 (2); M=K, n=3 (3)] were synthesized by the metathesis reactions of LM₂ with anhydrous YbCl₃ in 2:1 molar ratio in high yield. All the complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The influence of the alkali metal ions on the molecular structure of these lanthanide complexes has been elucidated.     

Structures and conformations of trifluoromethanesulfonic anhydride, (CF3SO2)2O, and bis(trifluoromethylsulfonyl)difluoromethane, (CF3SO2)2CF2

The geometric structures and conformational properties of trifluoromethanesulfonic anhydride, (CF₃SO₂)₂O, and bis(trifluoromethylsulfonyl)difluoromethane, (CF₃SO₂)₂CF₂ have been studied by gas electron diffraction (GED) and ab initio calculations (HF/3–21G*). The calculations predict for both systems two stable conformers with C₂ symmetry and one with C₁ symmetry. In both compounds structures with C₂ symmetry and dihedral angles SOSC ≈ 100° ((CF₃SO₂)₂O) and SCSC≈ 150° ((CF₃SO₂)₂CF₂ are lowest in energy. According to the GED analyses the dominant conformer of (CF₃SO₂)₂O₂ possesses C₂ symmetry with SOSC dihedral angles of 99.1(14)°. The presence of up to 30% of the two other conformers cannot be excluded; for (CF₃SO₂)₂CF₂ only one conformer with C₂ symmetry and SCSC dihedral angles of 143(2)° is observed. A complete set of geometric parameters is given.     

‘One-flask’ transformation of isocyanates and isothiocyanates to guanidines hydrochloride by using sodium bis(trimethylsilyl)amide

A ‘one-flask’ synthesis of guanidines was developed by reacting isocyanates and isothiocyanates with sodium bis(trimethylsilyl)amide followed by addition of primary or secondary amines with a catalytic amount of AlCl₃. The desired guanidines were obtained in good yields and the reaction was applicable to aliphatic and aromatic substrates. A plausible mechanism was proposed through the generation of cyanamide anion from isocyanates or isothiocyanates with sodium bis(trimethylsilyl)amide. Addition of amines and catalytic amount of AlCl₃ smoothly converted the cyanamides to the desired guanidines.     

Tris[bis(trimethysilyl)amido]zinkate von Lithium und Calcium

Tris[bis(trimethylsilyl)amido]zincates of Lithium and Calcium Calcium-bis[bis(trimethylsilyl)amide] and Bis[bis(trimethylsilyl)amido]zinc yield in 1,2-dimethoxyethane quantitatively Calcium-bis{tris[bis(trimethylsilyl)- amido]zincate} · 3DME. When THF is chosen as a solvent, the two reactants and the zincate form a temperature-independent equilibrium, whereas in benzene no reaction occurs. The tris[bis(trimethylsilyl)amido]zincate anion displays characteristic ¹³C{¹H) and ²⁹Si{¹H] chemical shifts of 7 and ?8 ppm, respectively; the nature of the solvent, the cation and the complexating ligands don't influence the IR nor NMR data of the zincate anion and thus verify that [Ca(DME)₃]²⁺ and {Zn[N(SiMe_{3 2}]₃}^? appear as solvent separated ions, which is also confirmed by their insolubility in hydrocarbons.