LITHIUM ALKYL ALUMINATES AS ALKYL TRANSFER REAGENTS

Abstract

The invention relates to lithium alkyl aluminates according to the general formula Li[AlR.sub.4] and to a method for preparing same, starting from LiAlH.sub.4 and RLi in an aprotic solvent. The invention also relates to compounds according to the general formula Li[AlR.sub.4] which can be obtained using the claimed method, and to the use thereof. The invention also relates to the use of a lithium alkyl aluminate Li[AlR.sub.4] as a transfer reagent for transferring at least one radical R to an element halide or metal halide and to a method for transferring at least one radical R to a compound E(X).sub.q for preparing a compound according to the general formula E(X).sub.q-pR.sub.p, where E=aluminium, gallium, indium, thallium, germanium, tin, lead, antimony, bismuth, zinc, cadmium, mercury, or phosphorus, X=halogen, q=2, 3 or 4, and p=1, 2, 3 or 4. The invention also relates to compounds which can be obtained using such a method, to the use thereof, and to a substrate which has an aluminium layer or a layer containing aluminium on one surface.

Claims

1-14. (canceled)

15. A method for preparing lithium alkyl aluminates according to the general formula
Li[AlR.sub.4]  (I) wherein R is selected from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a (trialkylsilyl) alkyl radical R.sup.A—Si(R.sup.B).sub.3, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, wherein R.sup.A is selected from the group consisting of a (C1-C6) alkylene radical and a partially or fully halogenated (C1-C6) alkylene radical, R.sup.B radicals are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical and an O—R.sup.E alkyl ether radical, wherein radicals R.sup.E are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, comprising the step of: Reacting LiAlH.sub.4 with a compound according to the general formula RLi, wherein R is selected from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a (trialkylsilyl) alkyl radical R.sup.A—Si(R.sup.B).sub.3, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, wherein R.sup.A is selected from the group consisting of a (C1-C6) alkylene radical and a partially or fully halogenated (C1-C6) alkylene radical, R.sup.B radicals are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical and an O—R.sup.E alkyl ether radical, wherein radicals R.sup.E are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, in at least one aprotic solvent in a reaction vessel, wherein a molar ratio LiAlH.sub.4:RLi is ≥0.25.

16. The method according to claim 15, wherein R is selected from the group consisting of Me, Et, nPr, iPr, nBu, tBu, sBu, iBu, CH(Me)(iPr), CH(Me)(nPr), CH(Et).sub.2, CH(Et)(Me).sub.2, CH.sub.2C.sub.6H.sub.5, C.sub.6H.sub.5, CH.sub.2SiMe.sub.3, CH.sub.2SiEt.sub.3, CH.sub.2Si(Me).sub.2(OMe), CH.sub.2Si(Et).sub.2(OEt), CH.sub.2Si(Me)(tBu)(OMe), CH.sub.2Si(tBu)(C.sub.6H.sub.5)(OtBu) and CH.sub.2Si(iPr).sub.2(OiPr).

17. The method according to claim 15, wherein the reaction of LiAlH.sub.4 with compound RLi comprises the steps of: i) providing a solution or a suspension of LiAlH.sub.4 in a first solvent S1, ii) adding the compound RLi, wherein during and/or after the addition of RLi, a reaction of LiAlH.sub.4 with the compound RLi takes place.

18. The method according to claim 15, wherein the compound RLi is added in a form suspended or dissolved in a second solvent S2.

19. The method according to claim 18, wherein the second solvent S2 is miscible with or identical to the first solvent S1.

20. The method according to claim 18, wherein the first solvent S1 and the second solvent S2 are selected independently of one another from the group consisting of hydrocarbons, benzene and benzene derivatives.

21. The method according to claim 15, wherein the reaction of LiAlH.sub.4 with the compound RLi is carried out at an internal temperature T.sub.U of the reaction vessel, the internal temperature T.sub.U being between −30° C. and 100° C.

22. The method according to claim 17, wherein an internal temperature T.sub.H of the reaction vessel during and/or after the addition of the compound RLi is between −40° C. and 80° C.

23. The method according to claim 15, wherein the step comprising the reaction of LiAlH.sub.4 with compound RLi is followed by a further step comprising the isolation of Li[AlR.sub.4]: i) as a solution, comprising Li[AIR.sub.4] (I) and the at least one aprotic solvent, or ii) as a solid.

24. The method according to claim 15, wherein isolation comprises a filtration step.

25. (canceled)

26. (canceled)

27. Use of a lithium alkyl aluminate according to the general formula
Li[AlR.sub.4]  (I), obtained by the method according to claim 15, for preparing compounds according to the general formula
(R)EH.sub.2  (III), wherein R is selected from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a (trialkylsilyl) alkyl radical R.sup.A—Si(R.sup.B).sub.3, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, wherein R.sup.A is selected from the group consisting of a (C1-C6) alkylene radical and a partially or fully halogenated (C1-C6) alkylene radical, R.sup.B radicals are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical and an O—R.sup.E alkyl ether radical, wherein radicals R.sup.E are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene and E is selected from the group consisting of phosphorus, antimony and bismuth.

28. A method for preparing compounds according to the general formula
(R)EH.sub.2  (III), using a lithium alkyl aluminate according to the general formula Li[AlR.sub.4] (I), wherein R is selected from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a (trialkylsilyl) alkyl radical R.sup.A—Si(R.sup.B).sub.3, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, wherein R.sup.A is selected from the group consisting of a (C1-C6) alkylene radical and a partially or fully halogenated (C1-C6) alkylene radical, R.sup.B radicals are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical and an O—R.sup.E alkyl ether radical, wherein radicals R.sup.E are selected independently of one another from the group consisting of a (C1-C10) alkyl radical, a partially or fully halogenated (C1-C10) alkyl radical, a benzyl radical, a partially or fully substituted benzyl radical, a mononuclear or polynuclear arene, a partially or fully substituted mononuclear or polynuclear arene, a mononuclear or polynuclear heteroarene and a partially or fully substituted mononuclear or polynuclear heteroarene, comprising the steps of: a) providing a solution of lithium alkyl aluminate according to the general formula Li[AlR.sub.4] (I) in at least one aprotic solvent, b) reacting the solution from step a) with a compound EX3 in a reaction vessel, wherein E is selected from the group consisting of phosphorus, antimony and bismuth and X=halogen, and c) adding a solution or a suspension comprising a hydridic reducing agent in an aprotic solvent S.sub.Z, wherein a molar ratio EX.sub.3:Li[AIR.sub.4] (I) is ≥4 and a molar ratio EX.sub.3:reducing agent is ≤1.

29. The method according to claim 28, wherein the hydridic reducing agent is prepared in situ by reacting NaAlH.sub.4 with a glycol ether, wherein a molar ratio NaAlH.sub.4:glycol ether is 0.5.

30. The method according to claim 29, wherein the glycol ether is selected from the group consisting of a monoethylene glycol monoether, a diethylene glycol monoether, a triethylene glycol monoether, a monopropylene glycol monoether, a dipropylene glycol monoether and a tripropylene glycol monoether.

31. (canceled)

Description

[0157] Other characteristics, details, and advantages of the invention follow from the wording of the claims as well as from the following description of the embodiment examples based upon the figures. The following are shown:

[0158] FIG. 1: .sup.27Al-coupled .sup.1H-NMR spectrum of Li[AltBu.sub.4], prepared in accordance with Exemplary Embodiment 1, after simple recondensation,

[0159] FIG. 2: .sup.1H-coupled .sup.27Al-NMR spectrum of Li[AltBu.sub.4], prepared in accordance with Exemplary Embodiment 1, after simple recondensation,

[0160] FIG. 3: .sup.27Al-coupled .sup.13C-NMR spectrum of Li[AltBu.sub.4], prepared in accordance with Comparative Example 1, after simple recondensation,

[0161] FIG. 4: .sup.1H-decoupled .sup.27Al-NMR spectrum of Li[AltBu.sub.4], prepared in accordance with Exemplary Embodiment 1, after simple recondensation,

[0162] FIG. 5: .sup.27Al-coupled .sup.1H-NMR spectrum of Li[Al(CH.sub.2SiMe.sub.3).sub.4], prepared in accordance with Exemplary Embodiment 2, after simple recondensation,

[0163] FIG. 6: .sup.1H-coupled .sup.27Al-NMR spectrum of Li[Al(CH.sub.2SiMe.sub.3).sub.4], prepared in accordance with Exemplary Embodiment 2, after simple recondensation, and

[0164] FIG. 7: .sup.1H-coupled .sup.31P-NMR spectrum of tBuPH.sub.2, prepared in one-pot synthesis in accordance with Exemplary Embodiment 4, after fractional distillation.

[0165] The NMR spectra shown in FIG. 1 to FIG. 6 were taken up in THF-.sub.d8. n-decane was used as solvent for the measurement of the NMR spectrum shown in FIG. 7. The chemical shift δ is plotted in ppm in each case on the x-axis. The respective temperatures (in K) and frequencies (in MHz) at which the individual NMR spectra were recorded can be gathered from the process specifications, or more precisely from the respective evaluations of the NMR spectra shown in FIG. 1 to FIG. 7.

[0166] FIG. 1 shows a .sup.27Al-coupled .sup.1H-NMR spectrum of Li[AltBu.sub.4], prepared in accordance with an embodiment of the claimed method (see Exemplary Embodiment 1). The product Li[AltBu.sub.4] was isolated by simple condensation of the solvent n-pentane under fine vacuum (10.sup.−2 to 10.sup.−3 mbar). As can be seen in FIG. 1, only one signal is observed at a chemical shift δ.sub.H of 0.91 ppm. Splitting of the signal into a sextet with a coupling constant .sup.3J.sub.HAl=4 Hz is due to the nuclear spin quantum number of the coupling aluminum nucleus. The fact that only one signal can be observed in the .sup.27Al-coupled .sup.1H-NMR spectrum shown in FIG. 1 suggests a complete and selective reaction to the desired target product Li[AltBu.sub.4].

[0167] FIG. 2 shows a .sup.1H-coupled .sup.27Al-NMR spectrum of Li[AltBu.sub.4]. The only signal at a chemical shift of δ.sub.Al=143.9 ppm appears due to the coupling to 36 hydrogen atoms as multiplet, which—in accordance with the .sup.27Al-coupled .sup.1H-NMR spectrum of Li[AltBu.sub.4] (see FIG. 1)—has a coupling constant .sup.3J.sub.AlH=4 Hz.

[0168] FIG. 3 shows a .sup.27Al-coupled .sup.13C-NMR spectrum of Li[AltBu.sub.4] with a sextet as the only signal at a chemical shift δ.sub.C=19.5 ppm. One coupling constant .sup.1J.sub.CAl is 76 Hz. The same value was determined via satellites in a .sup.1H-decoupled .sup.27Al-NMR spectrum of Li[AltBu.sub.4] (see FIG. 4).

[0169] FIG. 5 shows a .sup.27Al-coupled .sup.1H-NMR spectrum of Li[Al(CH.sub.2SiMe.sub.3).sub.4]. Two singlets can be observed for one CH.sub.2SiMe.sub.3 radical, wherein the CH.sub.2 unit is detected at a chemical shift of δ.sub.H=−2.22 ppm and the SiMe.sub.3 group at a chemical shift δ.sub.H=0.21 ppm. A .sup.1H-coupled .sup.27Al-NMR spectrum of Li[Al(CH.sub.2SiMe.sub.3).sub.4] (FIG. 6) shows only one signal at a chemical shift of δ.sub.Al=150.4 ppm. This suggests a complete and selective reaction to the desired product Li[Al(CH.sub.2SiMe.sub.3).sub.4]. The signal observed in the .sup.1H-coupled .sup.27Al-NMR spectrum (FIG. 6) is downfield-shifted compared to the corresponding signal of Li[AltBu.sub.4] (see FIG. 2). This can be explained by a comparatively lower electron density at the aluminum due to the less strong +1 effect of the CH.sub.2SiMe.sub.3 radical. A coupling constant .sup.2J.sub.AlH=9.1 Hz was determined based on the .sup.1H-coupled .sup.27Al-NMR spectrum (FIG. 6).

[0170] FIG. 7 shows a .sup.1H-coupled .sup.31P-NMR spectrum of tBuPH.sub.2 (TBP) prepared in one-pot synthesis in accordance with Exemplary Embodiment 4, comprising isolation by fractional distillation. It can be seen from the .sup.31NMR spectrum that the preparation of the desired product tBuPH.sub.2 was effected selectively. The solvent n-decane used and the target compound tBuPH.sub.2 have significantly different boiling points. Consequently, the two compounds were completely separated from one another by means of fractional distillation.

Process Specifications for the Synthesis of Li[AltBu.sub.4], Li[Al(CH.sub.2SiMe.sub.3).sub.4], PCl.sub.2tBu, tBuPH.sub.2, PCltBu.sub.2, PtBu.sub.3, ZntBu.sub.2, AltBu.sub.3 and Al(CH.sub.2SiMe.sub.3).sub.3

Materials and Methods:

[0171] All reactions were carried out in a protective gas atmosphere. Work was carried out using conventional Schlenk techniques, with nitrogen or argon being used as protective gas. The corresponding vacuum rakes or Schlenk lines were connected to rotary vane pumps made by Vacuubrand. The educts, reagents and synthesized products were weighed and stored in glove boxes made by MBraun (model MB 150 BG-1 or Lab Master 130) under a nitrogen atmosphere.

[0172] The solvents used were dried according to standard procedures and stored in stainless steel columns over suitable drying agents (molecular sieve, aluminum oxide, copper catalyst). Solvents CDCl.sub.3 and CD.sub.2Cl.sub.2 were dehydrated over molecular sieve 3 Å, condensed and then stored over molecular sieve 3 Å. In the case of gas injections of NH.sub.3, said gas was first passed through a drying tube with KOH cookies.

[0173] All nuclear magnetic resonance spectroscopic measurements were performed in automated mode on an AV II 300 instrument or in manual mode on an AV III HD 250, AV III HD 300 or AV III 500 instrument. The heteronuclear NMR spectra .sup.7Li, .sup.13C, .sup.27Al, .sup.29Si, .sup.31P were measured as standard .sup.1H-broadband decoupled spectra at 300 K. Where .sup.27Al- or .sup.31P-NMR spectra were measured both as .sup.1H decoupled and H coupled spectra, direct discrimination takes place such that the former is marked with .sup.27Al{.sup.1H}/.sup.31P{.sup.1H} and the latter with .sup.27Al/.sup.31P. .sup.1H and .sup.13C-NMR spectra were calibrated to the corresponding residual proton signal of the solvent as an internal standard: .sup.1H: C.sub.6D.sub.6: 7.16 ppm (s), THF-d.sub.8: 1.72 ppm (brs). .sup.13C: C.sub.6D.sub.6: 128.0 ppm (t), THF-d.sub.8: 25.2 ppm (quin). The chemical shifts are indicated in ppm and refer to the δ scale. All signals are provided with the following abbreviations according to their splitting pattern: s (singlet), quint (quintet), sext (sextet) or sept (septet); br (broad). The coupling between two nuclei A and B via n bonds is indicated by the coupling constant of the form .sup.nJ.sub.AB in hertz (Hz).

[0174] In substance, the measurements of infrared spectra were usually performed on an Alpha ATR-IR spectrometer made by Bruker. The absorption bands are indicated in wave number (cm.sup.−1), and the intensity is described with the following abbreviations: w (weak), m (moderate), st (strong), vst (very strong), br (broad). The spectra were always normalized to the band with the highest intensity.

[0175] The elemental analyses were carried out on a vario MICRO cube combustion device made by Elementar. Sample preparation was carried out in a glove box flooded with nitrogen by weighing the substance in tin crucibles, which were cold-welded and stored in a protective gas atmosphere until measurement. The elements of hydrogen, carbon and nitrogen were determined by means of a combustion analysis, wherein the information is always given in mass percent.

[0176] The thermogravimetric investigations were performed on a TGA/DSC 3+ STAR system made by Mettler Toledo. In the process, a coupled SDTA measurement was performed for each TGA. The samples were measured in aluminum oxide, aluminum or sapphire crucibles, depending on the method or state of aggregation. The sample was heated at a specific heating rate from 25° C. to the final temperature. The evaluation of the spectra obtained was carried out with STARe software made by Mettler Toledo.

Exemplary Embodiment 1: Preparation of Li[AltBu.SUB.4.] in n-pentane

[0177] LiAlH.sub.4 (150 mg, 3.95 mmol, 1.00 eq) was provided in 10 mL of n-pentane and a solution of tBuLi in n-hexane (8.64 mL, 1.83 M, 15.8 mmol, 4.00 eq) was added dropwise. The LiAlH.sub.4 used was observed to dissolve while a colorless solid precipitated. The colorless suspension was stirred for 16 h at room temperature. The emulsion-like reaction mixture was filtered, the filter cake was washed with 5 mL of n-pentane and the solvent of the filtrate was removed in a fine vacuum (10.sup.−2 to 10.sup.−3 mbar). The desired product was obtained as a colorless solid. The yield was 80% (824 mg, 3.14 mmol).

[0178] Alternatively, the product was isolated by decanting and subsequent drying. n-hexane and n-decane, for example, were used as alternative solvents.

[0179] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=1.10 (s, CMe.sub.3); .sup.1H-NMR (THF-d.sub.8, 500 MHz, 300 K): δ/ppm=0.91 (sext, .sup.3J.sub.HAl=4 Hz, CMe.sub.3); .sup.1H{.sup.27Al}-NMR (THF-d.sub.8, 500 MHz, 300 K): δ/ppm=0.91 (s, CMe.sub.3); .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=33.3 (s, CMe.sub.3); .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=19.5 (sext, .sup.1J.sub.CAl=76 Hz, CMe.sub.3), 35.1 (brs, CMe.sub.3); .sup.7Li-NMR (THF-d.sub.8, 117 MHz, 300 K): δ/ppm=−0.48 (s); .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=143.9 (m, .sup.3J.sub.AlH=4 Hz); .sup.27Al{.sup.1H}-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=143.9 (s); IR: {tilde over (υ)}/cm.sup.−1=2955 (m), 2933 (m), 2864 (m), 2814 (vst), 1496 (w), 1467 (m), 1382 (m), 1259 (w), 1170 (w), 1005 (w), 916 (m), 805 (st), 784 (vstbr), 557 (w), 523 (st), 439 (st).

Exemplary Embodiment 2: Preparation of Li[Al(CH.SUB.2.SiMe.SUB.3.).SUB.4.] in n-pentane

[0180] LiAlH.sub.4 (100 mg, 2.64 mmol, 1.00 eq) was suspended in 10 mL of n-pentane and cooled to 0° C. A solution of LiCH.sub.2SiMe.sub.3 (992 mg, 10.5 mmol, 4.00 eq) in 15 mL of n-pentane was added dropwise at room temperature. The colorless reaction mixture was stirred for 1 h at 0° C., then for 48 h at room temperature. The precipitated colorless solid was filtered and the solvent of the filtrate was removed in a fine vacuum (10.sup.−2 to 10.sup.−3 mbar). The product was obtained as a colorless solid with a yield of 39% (399 mg, 1.04 mmol).

[0181] The yield can be increased by repeatedly extracting the filter cake.

[0182] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=−2.04 (s, 8H, CH.sub.2SiMe.sub.3), 0.18 (s, 36H, CH.sub.2SiMe.sub.3); .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=−2.22 (s, 8H, CH.sub.2SiMe.sub.3), 0.21 (s, 36H, CH.sub.2SiMe.sub.3); .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=−4.6 (s, CH.sub.2SiMe.sub.3), 3.6 (s, CH.sub.2SiMe.sub.3); .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=−7.0 (s, CH.sub.2SiMe.sub.3), 6.0 (s, CH.sub.2SiMe.sub.3); .sup.7Li-NMR (C.sub.6D.sub.6, 117 MHz, 300 K): δ/ppm=1.3 (s); .sup.7Li-NMR (THF-d.sub.8, 117 MHz, 300 K): δ/ppm=1.3 (s); .sup.27Al-NMR (C.sub.6D.sub.6, 130 MHz, 300 K): δ/ppm=150.7 (quint, .sup.2J.sub.AlH=9.0 Hz); .sup.27Al-NMR (THF-ds, 130 MHz, 300 K): δ/ppm=150.4 (sept, .sup.2J.sub.AlH=9.1 Hz); .sup.27Al{.sup.1H}-NMR (C.sub.6D.sub.6, 130 MHz, 300 K): δ/ppm=150.6 (s); .sup.27Al{.sup.1H}-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=150.4 (s); .sup.29Si{.sup.1H}-NMR (THF-d.sub.8, 99 MHz, 300 K): δ/ppm=−3.9 (s); IR: {tilde over (υ)}/cm.sup.−1=2945 (m), 2890 (w), 2815 (w), 2787 (w), 1430 (w), 1241 (st), 1046 (w), 935 (w), 851 (vst), 811 (vst), 714 (vst), 668 (st), 603 (w), 454 (st); elemental analysis: for C.sub.16H.sub.44AlLiSi.sub.4: calculated: C: 50.20%, H: 11.59%, N: 0.00%, found: C: 49.53%, H: 10.93%, N: 0.25%. The determined nitrogen content of the sample can be explained by the sample's preparation in a nitrogen-flooded glove box.

Exemplary Embodiment 3: Transfer of One Tert-Butyl Group to PCl.SUB.3 .in n-Pentane Using Li[AltBu.SUB.4.] as Transfer Reagent

[0183] PCl.sub.3 (746 mg, 5.43 mmol, 4.00 eq) was provided in 15 mL of n-pentane and cooled to 0° C. A solution of Li[AltBu.sub.4] (356 mg, 1.36 mmol, 1.00 eq) in 20 mL of n-pentane was added dropwise, wherein precipitation of a colorless solid was observed. The reaction mixture was stirred for 16 h at room temperature and then examined by means of .sup.31P-NMR spectroscopy.

[0184] Synthesis was alternatively carried out, for example, in toluene, n-hexane and n-decane. Distillation of PCl.sub.2tBu from toluene provided an 84% yield.

[0185] .sup.31P-NMR (n-pentane, 101 MHz, 300 K): δ/ppm=197.2.

[0186] The chemical shift observed is consistent with that reported in the literature for PCl.sub.2tBu. (Y. Liu, B. Ding, D. Liu, Z. Zhang, Y. Liu, W. Zhang, Res. Chem. Intermed. 2017, 43, 4959-4966)

Exemplary Embodiment 4: Preparation of tBuPH.SUB.2 .Using a Solution of Li[AltBu.SUB.4.] in n-Decane Prepared In Situ (One-Pot Synthesis)

[0187] PCl.sub.3 (1.45 g, 10.6 mmol, 4.00 eq) was provided in 15 mL of n-pentane and cooled to 0° C. A solution of Li[AltBu.sub.4] prepared in situ based on LiAlH.sub.4 (100 mg, 2.65 mmol, 1.00 eq) and tBuLi (5.8 mL, 1.83 M, 10.6 mmol, 4.00 eq) in 20 mL of n-decane was slowly added dropwise, wherein a colorless solid precipitated. The reaction mixture was stirred at room temperature for 1 hr, cooled to 0° C. and mixed with Na[AlH.sub.2(OC.sub.2H.sub.4OC.sub.2H.sub.4OnBu).sub.2] prepared in situ based on NaAlH.sub.4 (570 mg, 10.6 mmol, 4.00 eq) and 2-(2-butoxyethoxy)ethanol (3.42 g, 21.1 mmol, 8.00 eq) in 10 mL of n-decane. The reaction mixture was slowly heated to room temperature and stirred for 1 h. The product was recondensed together with n-decane in a fine vacuum (10.sup.−2 to 10.sup.−3 mbar). The desired product tBuPH.sub.2 (850 mg, 9.43 mmol) was isolated by fractional distillation to give an 89% yield of a colorless liquid.

[0188] The reaction can be carried out in an analogous manner in n-pentane, but the latter cannot be separated from the product by fractional distillation.

[0189] Intermediate: .sup.31P-NMR (n-decane, 101 MHz, 300 K): δ/ppm=197.2.

[0190] Final product: .sup.31P-NMR (n-decane, 101 MHz, 300 K): δ/ppm=−80.3.

Exemplary Embodiment 5: Transfer of Two Tert-Butyl Groups to PCl.SUB.3 .in n-Hexane Using Li[AltBu.SUB.4.] as Transfer Reagent

[0191] Li[AltBu.sub.4] (75 mg, 0.29 mmol, 2.00 eq) was provided in 8 mL of n-hexane, cooled to 0° C. and mixed with PCl.sub.3 (80 mg, 0.58 mmol, 4.00 eq). The reaction mixture was heated to room temperature and stirred for 16 h. The slightly yellow suspension was filtered through a syringe filter and the filtrate was examined by means of .sup.31P-NMR spectroscopy.

[0192] .sup.31P-NMR (n-pentane, 101 MHz, 300 K): δ/ppm=144.9.

The chemical shift observed is consistent with that reported in the literature for PCltBu.sub.2. (F. Eisenträger, A. Göthlich, I. Gruber, H. Heiss, C. A. Kiener, C. Krüger, J. Ulrich Notheis, F. Rominger, G. Scherhag, M. Schultz, B. F. Straub, M. A. O. Volland, P. Hofmann, New J. Chem. 2003, 27, 540-550)

Exemplary Embodiment 6: Transfer of Three Tert-Butyl Groups to PCl.SUB.3 .in Toluene Using Li[AltBu.SUB.4.] as Transfer Reagent

[0193] Li[AltBu.sub.4] (75 mg, 0.29 mmol, 3.00 eq) was provided in 8 mL of toluene and cooled to 0° C. PCl.sub.3 (53 mg, 0.39 mmol, 4.00 eq) was added dropwise. The reaction mixture was heated to room temperature and stirred for 16 h. The slightly yellow suspension was filtered through a syringe filter and the filtrate was examined by means of .sup.31P-NMR spectroscopy.

[0194] .sup.31P-NMR (toluene, 101 MHz, 300 K): δ/ppm=58.0.

The chemical shift observed is consistent with that reported in the literature for PtBu.sub.3. (L. Rösch, W. Schmidt-Fritsche, Z. Anorg. Allg. Chem. 1976, 426, 99-106)

Exemplary Embodiment 7: Transfer of Two Tert-Butyl Groups to ZnCl.SUB.2 .in n-Hexane Using Li[AltBu.SUB.4.] as Transfer Reagent

[0195] ZnCl.sub.2 (100 mg, 0.73 mmol, 1.00 eq) was provided in 10 mL of n-hexane and cooled to −40° C. A solution of Li[AltBu.sub.4] (96 mg, 0.37 mmol, 0.50 eq) in 10 mL of n-hexane was added dropwise. The grayish suspension was kept at a temperature of −40° C. for 8 h and then slowly heated to room temperature. The suspension was filtered, cooled to −10° C. and freed from the solvent. ZntBu.sub.2 was obtained after repeated freeze-drying as a colorless solid with a yield of approximately 30% (40 mg, 0.22 mmol). The colorless solid can be sublimated under slightly reduced pressure at room temperature or recondensed at 40° C.

[0196] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=0.85 (s, CMe.sub.3).

No signal was detected in the .sup.7Li-NMR spectrum or in the .sup.27Al-NMR spectrum. A complete reaction was therefore effected.

Exemplary Embodiment 8: Transfer of Three Tert-Butyl Groups to AlCl.SUB.3 .in n-Pentane Using Li[AltBu.SUB.4.] as Transfer Reagent

[0197] AlCl.sub.3 (70 mg, 0.53 mmol, 1.00 eq) was provided in 10 mL of n-pentane, cooled to −40° C. and mixed with a solution of Li[AltBu.sub.4] (417 mg, 1.59 mmol, 3.00 eq) in 20 mL of n-pentane. The reaction mixture was stirred for 3 h at −40° C. and for 16 h at room temperature. The slightly gray suspension was filtered at 0° C. and the solvent of the filtrate was removed at −10° C. The product AltBu.sub.3 was obtained in the form of colorless crystals with a yield of 82% (345 mg, 1.74 mmol).

[0198] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=1.18 (s, CMe.sub.3), .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=32.0 (CMe.sub.3).

[0199] The quaternary carbon atom was not detected in the .sup.13C-NMR spectrum.

Exemplary Embodiment 9: Transfer of Three Tert-Butyl Groups to AlCl.SUB.3 .in n-Pentane Using Li[AltBu.SUB.4.] as Transfer Reagent on a Larger Scale

[0200] AlCl.sub.3 (700 mg, 5.30 mmol, 1.00 eq) was provided in 120 mL of n-pentane, cooled to −40° C. and mixed with a solution of Li[AltBu.sub.4] (4.17 g, 15.9 mmol, 3.00 eq) in 250 mL of n-pentane which was pre-cooled to 0° C. The reaction mixture was stirred for 10 h at −40° C. and for 16 h at room temperature. The gray suspension was filtered at 0° C. and the solvent of the filtrate was removed at −10° C. The product was obtained in the form of a crystalline solid with a yield of 76% (3.19 g, 16.1 mmol).

Exemplary Embodiment 10: Transfer of Three CH.SUB.2.SiMe.SUB.3 .Groups to AlCl.SUB.3 .in n-Pentane Using Li[Al(CH.SUB.2.SiMe.SUB.3.).SUB.4.] as Transfer Reagent

[0201] AlCl.sub.3 (80 mg, 0.61 mmol, 1.00 eq) was provided in 10 mL of n-pentane, cooled to −40° C. and mixed with a solution of Li[Al(CH.sub.2SiMe.sub.3).sub.4] (701 mg, 1.59 mmol, 3.00 eq) in 10 mL of n-pentane. The reaction mixture was stirred for 6 h at −40° C. and for 16 h at room temperature. After filtration, the solvent of the filtrate was removed at −10° C. in a fine vacuum (10.sup.−2 to 10.sup.−3 mbar). The product was recondensed in a fine vacuum (10.sup.−2 to 10.sup.−3 mbar) at 55° C. and obtained as a colorless liquid. The yield was 67% (424 mg, 1.47 mmol).

[0202] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=−2.00 (s, 6H, CH.sub.2SiMe.sub.3), −0.25 (s, 27H, CH.sub.2SiMe.sub.3).

[0203] It is clear that the invention relates to lithium alkyl aluminates according to the general formula Li[AlR.sub.4] and to a method for preparing same, starting from LiAlH.sub.4 and RLi in a non-ethereal solvent. The invention also relates to compounds according to the general formula Li[AlR.sub.4] which can be obtained using the claimed method, and to the use thereof. The invention further relates to the use of a lithium alkyl aluminate according to the general formula Li[AlR.sub.4] as a transfer reagent for transferring at least one radical R to an element halide or metal halide and to a method for transferring at least one radical R to a compound according to the general formula E(X).sub.q for preparing a compound according to the general formula E(X).sub.q-pR.sub.p. E is selected from the group consisting of aluminum, gallium, indium, thallium, germanium, tin, lead, antimony, bismuth, zinc, cadmium, mercury and phosphorus, X=halogen, q=2, 3 or 4, and p=1, 2, 3 or 4. The invention also relates to compounds which can be obtained according to an embodiment of such a method, to the use thereof, and to a substrate which has an aluminum layer or a layer containing aluminum on one surface.

[0204] With the claimed method, defined lithium alkyl aluminates according to the general formula Li[AlR.sub.4] (I) can be prepared in a simple, cost-effective and reproducible manner in high purity and good yields. The method can also be carried out on an industrial scale. Coordinating solvents, in particular ethers, are advantageously dispensed with. The compounds according to the general formula Li[AlR.sub.4] are also characterized by the fact that, also in the form of their parent solutions, they enable selective transfer of one or more alkyl radicals R to a plurality of metal halides and elemental halides. Under the otherwise chosen reaction conditions, only by-products that are relatively easy to separate accrue, i.e. normally LiAlX.sub.4 and in some cases LiX. It is furthermore advantageous that in the case of a transfer of four radicals R based on one molar equivalent of Li[AlR.sub.4] (I), the resulting salt load is significantly reduced as compared to when using an alkylation reagent, by means of which only one radical R can be transferred per molar equivalent. The alkylation products are in turn characterized by a high purity and are therefore particularly suitable as precursors for vapor deposition methods. The compounds AlR.sub.3 which can be prepared by the claimed method are suitable as precursors for preparing high-quality aluminum layers or layers containing aluminum.

[0205] All features and advantages resulting from the claims, the description and the figures, including constructive details, spatial arrangements and method steps, can be essential to the invention, both in themselves and in the most diverse combinations.