Method For The Production Of Salts Of Weakly Coordinating Anions, Salts Thereof And Use Thereof

Abstract

The invention relates to a method for the production of salts of weakly coordinating anions of the type according to the following formula (1), (2) or (3): M[F—X(OR F)m]z (1), M[(FRO)mX—F—X(ORF)m]z (2), M[(FRO)mX—F—X(ORF)n—F—X(ORF)m]z (3), these salts of weakly coordinating anions and use thereof.

Description

EXAMPLES

Because of the sensitivity to hydrolysis and oxidation of AlMe₃, all work was carried out so as to exclude air and moisture, in appropriate apparatus and under an inert N₂ atmosphere with Schlenk and glove-box techniques. The glass apparatus was closed in part with stopcocks from J. YOUNG company or glass stoppers and was heated under an oil-pump vacuum before beginning the experiment. The solvent was dried by standard methods, distilled and degassed and stored under nitrogen over a molecular sieve (400 pm). To determine the amount of gas generated in the reaction, a water-filled, gauged glass tube was connected by tubing to the apparatus. The gas volume could be deduced from the displacement of the water.

NMR Spectra

NMR-spectra were recorded using CD₂Cl₂-solvent at 20° with a BRUKER AC spectrometer, with SiMe₄ (¹H, ¹³C) and AlCl₃(²⁷Al) as references. The shifts are reported in ppm.

• s=singlet, d=doublet, q=quartet, m=multiplet; j=coupling constant (hz)

HiResESI Spectra

HiResESI spectra were recorded using CD₂Cl₂-solvent at 200, using an lonSpec Ultima FT-ICR-MS.

In the following examples R^F is (F₃C)₃C.

Example 1

Preparation of Aq[F—Al(OR^F)₃]pentane

AgBF₄+AlMe3+3HOR^F→Ag[F—Al(OR^F)₃]+3CH₄+BF₃

In a 250 ml two-necked flask, which is fitted with a reflux condenser cooled by cryostat to −20° C., 1.40 ml (2.82 mol) AlMe₃ (dissolved in n-heptane, c=2.0 mol/l) is introduced into about 20 ml of pentane at 0° C.

Then 1.18 ml (8.47 mmol) of alcohol R^FOH is instilled with further stirring. After full methane formation (190 ml; 100%), 0.550 g (2.82 mmol) of solid light beige AgBF₄-salt is added at one time to the mixture of the already formed Al(OR^F)₃ using a Schlenk vessel. With stirring, the salt reacts with the Al(OR^F)₃, whereby a light beige residue forms. After the gas formation of BF₃ (31 ml; 100%), the solvent is removed under high vacuum at 0° C. A bright yellow powder remains, which is weighed. This corresponds to the desired product Ag[F—Al(OR^F)₃] (yield: 2.375 g; 98%).

TABLE 1
13C- and 27Al-NMR Data for the Compound Ag[F—Al(ORF)3]
compound/fragment	NMR-nucleus	δ [ppm] exp.
OC(CF3)3	13C	119.3q; 1JCF = 290.0 Hz
OC(CF3)3		80.6 wide
[F—Al(ORF)3]−	27Al	41d; 1JAlF = 67.6 Hz

The HiResESI spectrum in CH₂Cl₂ confirms the theoretical mass of 751 for the anion [F—Al(OR^F)₃]⁻.

Example 2

Preparation of [NBu₄] [F—Al(OR^F)₃]pentane

NBu₄BF₄+AlMe₃+3HOR^F→[NBU₄][F—Al(OR^F)₃]+3CH₄+BF₃

In a two-necked flask, which is fitted with a reflux condenser cooled by cryostat to −20° C., 1.40 ml (2.82 mol) of AlMe₃ (dissolved in n-heptane, c=2.0 mol/l) is introduced into about 20 ml of pentane. At 0° C., 1.18 ml (8.47 mmol) R^FOH is instilled with stirring and reflux. After full methane formation (190 ml; 100%), white Al(OR^F)₃ appears. After the addition of 0.929 g (2.82 mmol) of the white NBu₄BF₄-salt using a Schlenk apparatus, a bright residue forms with time, which precipitates. The formation of BF₃ gas is complete at 62 ml (100%). After removal of the solvent under high vacuum, a bright solid powder remains, which is constant in weight and corresponds to the product [(NBu₄][F—Al(OR^F)₃] (yield: 2.394 g; 85%).

TABLE 2
NMR Data for [(NBu4][F—Al(ORF)3]
compound/fragment	NMR-nucleus	δ [ppm] exp.
N (C4H9)4+	1H	0.95m + 1.37m + 1.55m + 3.05m
OC(CF3)3	13C	121.6q; 1JCF = 291.6 Hz
OC(CF3)3		79.9 wide
N(C4H9)4+		13.2s + 19.6s + 23.9s + 58.9s
[F—Al(ORF)3]−	27Al	42s

The HiResESI spectrum clearly indicates the mass of the corresponding [F—Al(OR^F)₃]⁻-anions at 751, which is analogous to the mass of anions in the silver salt compound Ag[F—Al(OR^F)₃ of Example 1.

Example 3

Preparation of Aq(R^FO)₃Al—F—Al(OR^F)₃]pentane

AgBF₄+2AlMe₃+6HOR^F→Ag[(R^FO)₃Al—F—Al(OR^F)₃]+6CH₄+BF₃

In a 250 ml two-necked flask, which is fitted with a reflux condenser cooled by cryostat to 20° C., 1.40 ml (2.82 mol) AlMe₃ (dissolved in n-heptane, c=2.0 mol/l) is introduced into about 20 ml pentane at 0° C. While adding 1.18 ml (8.47 mmol) of R^FOH, 190 ml (100%) of methane forms. After gas evolution is complete, white Al(OR^F)₃ forms.

The AgBF₄-salt (0.275 g; 1.412 mmol) is added to the mixture at one time using a Schlenk apparatus. At once, a viscous light beige solid material forms in a colorless supernatant solution. The volume of evolving BF₃ gas is complete (31 ml; 100%). After decanting the solvent under high pressure, a beige, large-grained powder remains, which is constant in weight and corresponds to the product Ag[(R^FO)₃Al—F—Al(OR^F)₃] (yield: 1.939 g; 86%).

TABLE 3
NMR Data for Ag[(RFO)3Al—F—Al(ORF)3]
compound/fragment	NMR-nucleus	δ [ppm] exp.
OC(CF3)3	13C	120.9q; 1JCF = 291.1 Hz
OC(CF3)3		79.9 broad
[(RFO)3Al—F—Al(ORF)3]−	27Al	34s broad

Example 4

Preparation of [NBu₄][R^FO)₃Al—F—Al(OR^F)₃]

pentane

NBu₄BF₄+2AlMe₃+6HOR^F→[NBu₄][R^FO)₃Al—F—Al(OR^F)₃]+6CH₄+BF₃

In a 250 ml two-necked flask, which is fitted with a reflux condenser cooled by cryostat to −20° C., 1.40 ml (2.82 mol) of AlMe₃ (dissolved in n-heptane, c=2.0 mol/l) is introduced into about 20 ml pentane at 0° C. While adding 1.18 ml (8.47 mmol) of R^FOH, 190 ml (100%) of methane is formed After gas evolution is complete, white Al(OR^F)₃ forms.

The NBu₄BF₄-salt (0.464 g; 1.412 mmol) is added to the mixture at one time using a Schlenk apparatus. At once, a bright residue forms. The volume of evolving BF₃ gas is complete (31 ml; 100%). After decanting the solvent under high pressure, a colorless, slightly yellowish powder remains, which is constant in weight and corresponds to the product [NBu₄][(R^FO)₃Al—F—Al(OR^F)₃] (yield: 2.17 g; 89%).

TABLE 4
NMR Data for [NBu4][(RFO)3Al—F—Al(ORF)3]
	NMR-
compound/fragment	nucleus	δ [ppm] exp.
N(C4H9)4+	1H	0.98m + 1.37m + 1.55m + 3.01m
OC(CF3)3	13C	120.9q; 1JCF = 291.2 Hz
OC(CF3)3		80 broad
N(C4H9)4+		13.2s + 19.8s + 24.0s + 59.3s
[(RFO)3Al—F—Al(ORF)3]−	27Al	34s broad

Example 5

Preparation of [NBu₄][(R^FO)₃Al—F—Al(OR^F)₉—F—Al(OR^F)₃]

In a two-necked flask, which is fitted with a reflux condenser cooled by cryostat to −20° C., 1.40 ml (2.82 mol) of AlMe₃ (dissolved in n-heptane, c=2.0 mol/l) is introduced into about 30 ml of heptane at 0° C. With further stirring, 1.18 ml (8.47 mmol) R^FOH is added dropwise. White Al(OR^F)₃ forms. After complete methane generation, 0.464 g (1.41 mmol) of white NBu₄BF₄-salt, dissolved in about 5 ml CH₂Cl₂, is added to the mixture at one time. A dark yellow solution forms, which contains a small amount of light beige precipitate. After complete generation of BF₃ gas (31 ml; 100%), stirring is continued for about one hour at 0° C. Then, the solution is refluxed for about 2 hours and the solvent is removed under high vacuum. A light beige oily-solid residue in the amount of 2.453 g remains, which crystallizes from CH₂Cl₂. This yields the product: [NBu₄][(R^FO)₃Al—F—Al(OR^F)₂—F—Al(OR^F)₃].

TABLE 5
NMR Data for [NBu4][(RFO)3Al—F—Al(ORF)2—F—Al(ORF)3]
compound/fragment	NMR-nucleus	δ [ppm] exp.
N(C4H9)4+	1H	0.95m + 1.36m + .,49m + 3.03m
N(C4H9)4+	13C	13.3s + 19.9s + 24.1s + 59.4s
OC(CF3)3		120.9q; 1JCF = 291.1 Hz1)
		121.9q; 1JCF = 290.9 Hz2)
		120.8q; 1JCF = 290.9 Hz3)
OC(CF3)3		79.9 broad
[(RFO)3Al—F—Al(ORF)2—F—Al(ORF)3]−	27Al	35s, very broad

Claims

1. A method for preparing salts of weakly coordinating anions of the type corresponding to the following formula (1), (2) or (3): M[F—X(ORF)m]z  (1)M[(FRO)mX—F—X(ORF)m]z  (2)M[(FRO)mX—F—X(ORF)n—F—X (ORF)m]z  (3)

2. The method according to claim 1 for the production of salts of weakly coordinating anions of the type corresponding to the following formula (1′), (2′) or (3′): M[F—Al (ORF)3]z  (1)M[(FRO)3Al—F—Al(ORF)3]z  (2′)M[(FRO)Al—F—Al(ORF)—F—Al (ORF)3]z  (3′)

3. A method according to claim 1, wherein the aluminum trialkoxy compound Al(ORF)3 is reacted with the tetrafluoroborate salt M(BF4)z at a ratio of 1:1, if z is 1, or is reacted at a ratio of 2:1, if z is 2.

4. A method according to claim 1, wherein the aluminum trialkoxy compound Al(ORF)3 is reacted with the tetrafluoroborate salt M(BF4)z at a ratio of 2:1, if z is 1, or is reacted at a ratio of 4:1, if z is 2.

5. A method according to claim 1, wherein the organic, aprotic solvent is selected from the group consisting of pentane, hexane, heptane, octane, benzene, toluene, cresol, chlorobenzene and trichlorobenzene.

6. A method according to claim 1, wherein R is a radical selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, phenyl and tolyl.

7. A method according to claim 1, wherein RF is selected from the group consisting of linear or branched, partially or completely fluorinated C1 to C10 alkyl groups, partially or completely fluorinated C6 to C20 aryl groups, and partially or completely fluorinated C3 to C10 cycloalkyl groups.

8. A method according to claim 1, wherein, if z is 1, M is selected from the group consisting of alkali metal ions, In+, Ti+, Ag+, Cu+, NR′4+, PR′4+, wherein R′ is, independently in each case, hydrogen, a linear or branched C1 to C20-alkyl radical or substituted or unsubstituted aryl radical, and imidazolium, or, if z is 2, M is selected from the group consisting of Ni2+, Cu2+, Zn2+, Pd2+, Rh2+, and Pt2+.

9. A method according to claim 1, wherein, in a first step, the aluminum triorganyl compound AlMe3 is reacted with a partially or completely fluorinated alcohol FROH in pentane at a ratio of 1:3 and then, in a second step, the resulting aluminum trialkoxy compound Al(ORF)3 is reacted with tetrafluoroborate salt M(BF4)z at a ratio of 1:1, if z is 1, or at a ratio of 2:1, if z is 2, to yield a compound corresponding to formula (1′) above.

10. A method according to claim 1, wherein, in a first step, the aluminum triorganyl compound AlMe3 is reacted with a partially or completely fluorinated alcohol FROH in pentane at a ratio of 1:3 and, then in a second step, the resulting aluminum trialkoxy compound Al(ORF)3 is reacted with tetrafluoroborate salt M(BF4)z at a ratio of 2:1, if z is 1, or at a ratio of 4:1, if z is 2, to yield a compound corresponding to formula (2′) above.

11. A method according to claim 1, wherein, in a first step, the aluminum triorganyl compound AlMe3 is reacted with a partially or completely fluorinated alcohol FROH in heptane at a ratio of 1:3 and then, in a second step, the resulting aluminum trialkoxy compound Al(ORF)3 is reacted with tetrafluoroborate salt M(BF4)z at a ratio of 2:1 if z is 1, or at a ratio of 4:1, if z is 2, to yield a compound corresponding to formula (3′) above.

12. A method according to claim 9, wherein M is Ag+ or NBu4+ and RF is (F3C)3C.

13. A method according to claim 10 wherein M is Ag+ or NBu4+ and RF is (F3C)3C.

14. Salts of weakly coordinating anions corresponding to formula (3): M[(FRO)mX—F—X(ORF)n—F—X(ORF)m]z  (3)

15. The salts of weakly coordinating anions according to claim 14, represented by the formula (3′): M[(FRO)3Al—F—Al(ORF)2—F—Al(ORF)3]z  (3′)

16. The salts according to claim 14, wherein M is Ag+ or NBu4+ and RF is (F3C)3C.

17. (canceled)

18. An alkoxy compound of an element, represented by formula (4): X(ORF)m  (4)

19. The alkoxy compound of an element according to claim 18, wherein X is Al.

20. A method according to claim 11 wherein M is Ag+ or NBu4+ and RF is (F3C)3C.