TARGETED PRODUCTION OF 2,2,3,3-TETRASILYL TETRASILANE

Abstract

The present invention provides the octasilane 2,2,3,3-tetrasilyltetrasilane 1, compositions comprising one or more additional constituents that are not 1 as well as 2,2,3,3-tetrasilyltetrasilane 1, processes for preparing 2,2,3,3-tetrasilyltetrasilane 1 and mixtures of higher hydridosilanes that include 1. The present invention further provides for the use of 1 and mixtures of higher hydridosilanes including 1 for deposition of silicon-containing material.

Claims

1. 2,2,3,3-Tetrasilyltetrasilane of the formula 1, having: a molecular mass, determined by mass spectrometry, of 242 g/mol; a .sup.29Si NMR spectrum with 2 resonance signals, the first signal having a chemical shift of =92.71 ppm and the form of a quartet with a heteronuclear coupling .sup.1J.sub.SiH=201 Hz (SiH.sub.3), and the second signal a chemical shift of =150.42 ppm and the form of a multiplet with a heteronuclear coupling .sup.2J.sub.SiH=3 Hz, (Si.sub.q); a .sup.1H NMR spectrum with signals typical of SiH.sub.3 groups and a chemical shift in the region of 3-4 ppm, where an integration across these signals corresponds to a sum total of 18 protons and the chemical shifts of the .sup.29Si and .sup.1H NMR spectra are based on tetramethylsilane as a reference standard ##STR00010##

2. 2,2,3,3,4,4-Hexasilylpentasilane of the formula 2, having: a molecular mass, determined by mass spectrometry, of 332 g/mol; a .sup.29Si NMR spectrum with 4 resonance signals, the first signal having a chemical shift of =146.50 ppm and the form of a multiplet with a heteronuclear coupling of .sup.2J.sub.SiH=2.7 Hz (Si(SiH.sub.3).sub.3), the second signal a chemical shift of =135.26 ppm and the form of a multiplet with a heteronuclear coupling of .sup.2J.sub.SiH=3.0 Hz (Si(SiH.sub.3).sub.2), the third signal a chemical shift of =93.65 ppm and the form of a quartet with heteronuclear coupling constants of .sup.1J.sub.SiH=201.4 Hz and .sup.3J.sub.SiH=3.2 Hz (Si(SiH.sub.3).sub.2), and the fourth signal a chemical shift of =90.11 ppm and the form of a quartet with heteronuclear coupling constants of .sup.1J.sub.SiH=201.6 Hz, and .sup.3J.sub.SiH=3.6 Hz (Si(SiH.sub.3).sub.3); a .sup.1H NMR spectrum with signals typical of SiH.sub.3 groups and a chemical shift in the region of 3-4 ppm, where the chemical shift of the .sup.1H NMR spectrum is based on tetramethylsilane as reference standard ##STR00011##

3. A composition comprising the 2,2,3,3-tetrasilyltetrasilane of the formula 1 according to claim 1, and one or more additional constituents that are not 2,2,3,3-tetrasilyltetrasilane of the formula 1.

4. The composition according to claim 3, comprising at least 30 area % of the 2,2,3,3-tetrasilyltetrasilane, not more than 10 area % of 2,2,3,3,4,4-hexasilylpentasilane and not more than 30 area % of neopentasilane, where the difference from 100 area % includes higher hydridosilanes of the formula Si.sub.nH.sub.2n+m with m=0, 2 and n5, unconverted reactants and by-products that are not hydridosilanes, and where the stated area percentages are based on the total area of a gas chromatography measurement.

5. The composition according to claim 4, in the liquid phase under standard conditions/SATP, freed of unconverted reactants and by-products, comprising 50-70 area % of the 2,2,3,3-tetrasilyltetrasilane, 2,2,3,3,4,4-hexasilylpentasilane, and higher hydridosilanes of the formula Si.sub.nH.sub.(2n+m) with m=0, 2 and n>5, where the difference from 100 area % comprises nonvolatile higher hydridosilanes of the formula Si.sub.nH.sub.(2n+m) with m=0, 2 and n>11, and where the stated area percentages are based on the total area of a gas chromatography measurement.

6. The composition according to claim 3, wherein the one or more additional constituents that are not 2,2,3,3-tetrasilyltetrasilane of the formula 1 comprise 2,2,3,3,4,4-hexasilylpentasilane.

7. The composition according to claim 6, wherein the one or more additional constituents that are not 2,2,3,3-tetrasilyltetrasilane of the formula 1 further comprise neopentasilane.

8. The composition according to claim 3, wherein the one or more additional constituents that are not 2,2,3,3-tetrasilyltetrasilane of the formula 1 comprise: 2,2,3,3,4,4-hexasilylpentasilane, neopentasilane, and a compound of formula Si.sub.nH.sub.2n+m with m=0 or 2 and n>11.

9. A process for preparing a higher hydridosilane of the formula Si.sub.nH.sub.2n+m with m=0 or 2 and n5, comprising: a) providing one or more metal silanides of the formula M(Si.sub.nH.sub.2n+m).sub.o with 1n12, m=1, 1, o=1, 2 and M=alkali metal, alkaline earth metal; b) reacting the metal silanides of the formula M(Si.sub.nH.sub.2n+m).sub.o with 1n12, m=1, 1, o=1, 2 and M=alkali metal, alkaline earth metal, with one or more electrophiles selected from the group consisting of the element halides and the element organyl halides, where the subgroup of the element organyl halides comprises element alkyl or aryl halides, each of the 4th main group of the Periodic Table of the Elements; and c) working up the reaction mixture obtained from b) to obtain a mixture of hydridosilanes of the formula Si.sub.mH.sub.2m+2 with m5.

10. The 2,2,3,3-Tetrasilyltetrasilane according to claim 1, obtained by a process comprising: a) providing a metal silanide of the formula M(Si.sub.nH.sub.2n+m).sub.o with 1n12, m=1, 1, o=1, 2 and M=alkali metal, alkaline earth metal; b) reacting the metal silanide with an electrophile selected from the group consisting of the element halides and the element organyl halides, where the subgroup of the element organyl halides comprises element alkyl or aryl halides, each of the 4th main group of the Periodic Table of the Elements; and c) working up the reaction mixture obtained from b) to obtain the 2,2,3,3-tetrasilyltetrasilane.

11. A mixture of higher hydridosilanes of the formula Si.sub.nH.sub.2n+m with m=0, 2 and n5, obtained by a process comprising: a) providing a metal silanide of the formula M(Si.sub.nH.sub.2n+m).sub.o with 1n12, m=1, 1, o=1, 2 and M=alkali metal, alkaline earth metal; b) reacting the metal silanide with an electrophile selected from the group consisting of the element halides and the element organyl halides, where the subgroup of the element organyl halides comprises element alkyl or aryl halides, each of the 4th main group of the Periodic Table of the Elements; and c) working up the reaction mixture obtained from b) to obtain a mixture of silanes of the formula Si.sub.nH.sub.2n+m with m=0, 2 and n5.

12. (canceled)

Description

EXAMPLE 1

[0064] ##STR00007##

[0065] To a solution of 1.00 g NPS (6.6 mmol, 1 equivalent) in 6 ml of diethyl ether are gradually added, at 30 C., 3.95 ml of a 1.6 M solution of MeLi in diethyl ether (6.2 mmol, 0.95 eq.), and then the mixture was stirred at room temperature for 1 h. The solution of isotetrasilanyllithium thus obtained is added dropwise at 0 C. to a solution of 0.28 ml of dibromoethane (3.3 mmol, 0.55 eq.) in 12 ml of diethyl ether, and the mixture is stirred at room temperature for 45 minutes. Then the solvent is removed at 0 C. under reduced pressure, and the remaining residue is extracted 3 times with 15 ml each time of pentane and filtered off via a filter cannula. The pentane is removed by distillation from the soluble fraction at 0 C. under reduced pressure, and the remaining oily product mixture is recondensed at 38-40 C. at 0.05 mbar=5 Pa. This gives 0.21 g (28%) of pure 1 in the form of a clear oxidation-sensitive liquid.

EXAMPLE 2

[0066] ##STR00008##

[0067] To a solution of 1.00 g NPS (6.6 mmol, 1 equivalent) in 6 ml of diethyl ether are gradually added, at 30 C., 3.95 ml of a 1.6 M solution of MeLi in diethyl ether (6.2 mmol, 0.95 eq.), and then the mixture was stirred at room temperature for 1 h. The solution of isotetrasilanyllithium thus obtained is added dropwise at 0 C. to a solution of 0.61 g of tetrachlorosilane (3.6 mmol, 0.55 eq.) in 12 ml of diethyl ether, and the mixture is stirred at room temperature for 45 minutes. Then the solvent is removed at 0 C. under reduced pressure, and the remaining residue is extracted 3 times with 15 ml each time of pentane and filtered off via a filter cannula. The pentane is removed by distillation from the soluble fraction at 0 C. under reduced pressure, and the remaining oily product mixture is recondensed at 38-40 C. at 0.05 mbar=5 Pa. This gives 0.21 g (28%) of pure 1 in the form of a clear oxidation-sensitive liquid. The residue from the distillation is transferred to a sublimation apparatus and sublimed at 40-60 C. at 110.sup.3 mbar. This gives 40 mg (5%) of pure 2 in the form of a colourless oxidation-sensitive solid.

[0068] Characterization of 1:

[0069] .sup.29Si NMR (C.sub.6D.sub.6): =92.71 ppm (q, .sup.1J.sub.SiH=201 Hz, SiH.sub.3); 150.42 ppm (m, .sup.2J.sub.SiSiH=3 Hz, Si.sub.q)

[0070] .sup.1H NMR (C.sub.6D.sub.6): =3.48 ppm (s, 18H, SiH.sub.3)

[0071] MS: 242 (M+), 210 (M+-SiH.sub.4), 178 (M+-2 SiH.sub.4), 146 (M+-3 SiH.sub.4)

[0072] Characterization of 2:

[0073] .sup.29Si NMR (C.sub.6D.sub.6): =146.50 ppm (m, .sup.2J.sub.SiH=2.7 Hz, Si(SiH.sub.3).sub.3), 135.26 ppm (m, .sup.2J.sub.SiH=3.0 Hz, Si(SiH.sub.3).sub.2), 93.65 ppm (q, .sup.1J.sub.SiH=201.4 Hz, .sup.3J.sub.SiH=3.2 Hz, Si(SiH.sub.3).sub.3); 90.11 ppm (q, .sup.1J.sub.SiH=201.6 Hz, .sup.3J.sub.SiH=3.6 Hz, Si(SiH.sub.3).sub.2)

[0074] .sup.1H NMR (C.sub.6D.sub.6): =3.54-3.56 (m, SiH.sub.3)

[0075] MS: 332 (M.sup.+), 300 (M.sup.+-SiH.sub.4), 268 (M.sup.+-2 SiH.sub.4)

EXAMPLE 3

[0076] ##STR00009##

[0077] To 1.00 g NPS (6.6 mmol, 1 equivalent) is added, at 30 C. 0.20 ml of a 1.6 M solution of MeLi in diethyl ether (0.3 mmol, 0.05 equivalent), and then the mixture was stirred at 30 C. for 10 min. Subsequently, 0.03 g of tetrachlorosilane (0.1 mmol, 0.03 equivalent) is added dropwise to the reaction solution and the mixture is stirred at room temperature for 45 minutes. Then the solvent is removed under reduced pressure at 0 C., and the remaining oily product mixture is recondensed at 38-40 C. at 0.05 mbar=5 Pa. This gives 0.16 g (20%) of pure 1 in the form of a clear oxidation-sensitive liquid.

TABLE-US-00001 TABLE 1 Quantitative evaluation of the product mixture obtained according to Example 1 (route A, dibromoethane as electrophile).sup.. Amount used: 1 g of NPS 3 Octasilane Solid residue Soluble fraction (isolated) Theoretical 0.5 g LiBr 0.8 g higher silanes 0.8 g amount Experimental 0.4 g 0.4 g 0.2 g amount (after condensation) Analysis LiBr + nonvolatile 1, 2 further 1 polymeric oligomeric H- hydridosilanes* silanes.sup.# Yield 50% 25% .sup.GC-MS analysis reveals equal amounts of 1 and 3 (see FIG. 3). *determined by IR spectroscopy (FIG. 1) .sup.#determined by NMR spectroscopy (FIG. 2)

TABLE-US-00002 TABLE 2 Quantitative evaluation of the product mixture obtained according to Example 2 (route B, tetrachlorosilane as electrophile).sup.. Amount used: 1 g of NPS 3 Octasilane Solid residue Soluble fraction (isolated) Theoretical 0.25 g LiCl 0.8 g higher silanes 0.8 g amount Experimental 0.35 g 0.55 g 0.2 g amount (solid residue) (soluble fraction) (after condensation) Analysis LiCl + nonvolatile 1, 2 further 1 polymeric oligomeric H- hydridosilanes* silanes.sup.# Yield 70% 25% .sup.detection by means of GC-MS *determined by IR spectroscopy (FIG. 1) .sup.#determined by NMR spectroscopy (FIG. 2)

[0078] FIG. 2 shows the .sup.1H NMR spectrum of the extracted product mixture as results from the process according to the invention. The registered resonance signals in the region of 3-4 ppm are typical of SiH.sub.3 groups and reveal at least 3 species of hydridosilanes of the formula Si.sub.mH.sub.2m+2 with m>5.

[0079] A broad signal in this region which is typical of polymeric hydridosilanes is not registered.

[0080] The main constituents of the crude product mixture prior to distillative workup are 1 (at least 30%), 2 (at most 10%) and 3 (at most 30%), determined as area % in a gas chromatography measurement.

[0081] The finding is supported by the results from coupled gas chromatography and mass spectrometry studies; see FIG. 3.

[0082] Removal of the solid and volatile constituents (essentially 3) leaves, in the liquid phase under SATP, 50-70 area % of soluble higher silanes, the difference from 100 area % comprising nonvolatile higher hydridosilanes of the formula Si.sub.nH.sub.2n+m with m=0, 2, especially m=2 and n>11.

[0083] 1 can be isolated in pure form in about 25% yield.

[0084] The solid residue contains, as well as the LiX (X=Br, Cl) formed, also relatively small amounts of insoluble polymeric hydridosilanes. This becomes clear from the IR spectroscopy data disclosed in FIG. 1. The registered bands in the region of about 2100 cm.sup.1 and of about 800 cm.sup.1 are typical of compounds having SiH bonds. On contact with moisture, additional bands appear in the IR spectrum in the region of 3400 cm.sup.1 and 1600 cm.sup.1, which are attributable to adsorbed water and increase in intensity on prolonged contact with moisture; see lower IR spectrum in FIG. 1.

[0085] Further bands appear in the region of 1200 cm.sup.1 on prolonged contact with moisture, which are typical of siloxanes. They indicate the oxidation of the nonvolatile polymeric hydridosilanes to corresponding polymeric siloxanes as breakdown product.

[0086] Irrespective of the electrophile chosen in the process according to the invention, with regard to the solid residue obtained, identical results are obtained in the IR spectroscopy data. This residue is thus a mixture of LiX with X=Br or Cl and polymeric hydridosilanes, which, as well as a low vapour pressure, additionally feature sparing solubility in nonpolar solvents or nonpolar solvent mixtures.

[0087] The registered UV-Vis spectra of compound 1 and compound 2 are disclosed in FIG. 4 and FIG. 5 at concentrations of 1*10.sup.4 mol/L.