Stepwise fluorination of [MeAlN(2,6-i-Pr2C6H3)]3 using trimethyltin fluoride as fluorinating agent

doi:10.1016/S0022-1139(02)00285-3

Journal of Fluorine Chemistry

Volume 120, Issue 1, 1 March 2003, Pages 59-64

Dedicated to Professor Alan H. Cowley for his outstanding contributions in Chemistry

https://doi.org/10.1016/S0022-1139(02)00285-3 Get rights and content

Abstract

The fluorination of [MeAlN(2,6-i-Pr₂C₆H₃)]₃ 1 using 1 and 2 eq., respectively, trimethyltin fluoride leads to the mono- and difluoro compounds, [FAl(MeAl)₂(N(2,6-i-Pr₂C₆H₃))₃]·2THF 2 and [(FAl)₂MeAl(N(2,6-i-Pr₂C₆H₃))₃]·3THF 3, where each methyl group can be selectively exchanged for terminal fluorine atoms (AlF). The reaction of 1 and 3 eq. of trimethyltin fluoride leads to the trifluoro compound [FAlN(2,6-i-Pr₂C₆H₃)]₃·3THF 4 and [Me₂SnN(2,6-i-Pr₂C₆H₃)]₂ 5 as a by-product. The core of compound 5 consists of a tin–nitrogen four-membered Sn₂N₂ ring.

Graphic

Introduction

Since 1955, Ziegler and Köster [1], [2] had pioneered the preparation of dialkylaluminum fluorides, only a small number of other alkylaluminum fluorides [3], [4], [5], [6], [7] has been synthesized due to the lack of suitable fluorination routes. General attempts of selective fluorination have led to product mixtures.

Recently, Uhl et al. reported that the reaction of a carbaalane cluster (AlEt)₇(CCHC₆H₅)₂(CCH₂C₆H₅)₃H with HBF₄·OEt₂ yields the fluorine derivative (AlEt)₇(CCHC₆H₅)₂(CCH₂C₆H₅)₃(μ₃-F) [8]. In the past we have reported the facile preparation of groups 4–6 and main group fluorides [9], [10], [11] from their corresponding chlorides using trimethyltin fluoride as fluorinating reagent. Furthermore, based on this experience we have developed in recent years the chemistry of aminoalane mono- and difluorides [12] and trisylaluminum difluorides (trisyl=(Me₃Si)₃C) [13] using trimethyltin fluoride in methyl-fluorine exchange reactions with the concomitant generation of volatile tetramethyltin. However, a stepwise fluorination has not been realized until now.

Herein, we report the first controlled stepwise fluorination of [MeAlN(2,6-i-Pr₂C₆H₃)]₃ 1 [14] with trimethyltin fluoride in THF solution. However, the fluorination of 1 with 3 eq. of trimethyltin fluoride yields a mixture of [FAlN(2,6-i-Pr₂C₆H₃)]₃·3THF 4 and a four-membered tin–nitrogen Sn₂N₂ ring 5 in a molar ratio of 10:1.

Section snippets

Results and discussion

The reactions of trimethyltin fluoride in various stoichiometries with 1 in THF solution at room temperature leads to the colorless iminoalane fluoride-THF adducts [FAl(MeAl)₂(N(2,6-i-Pr₂C₆H₃))₃]·2THF 2 and [(FAl)₂MeAl(N(2,6-i-Pr₂C₆H₃))₃]·3THF 3, respectively, having terminal AlF bonds (Scheme 1). Increasing the amount to 3 eq. of trimethyltin fluoride at room temperature leads to the trifluoro iminoalane 4 and to a tin–nitrogen four-membered ring 5 (Scheme 2). In contrast to our previously

Experimental

All experiments were performed using standard Schlenk techniques under a dry nitrogen atmosphere, due to the sensitivity of the reactants and products towards air and moisture. All solvents were distilled from sodium/benzophenone and degassed prior to use. [MeAlN(2,6-i-Pr₂C₆H₃)]₃ 1 was prepared as described in the literature [14]. Elemental analyses were performed by the Analytisches Labor des Instituts für Anorganische Chemie der Universität Göttingen. NMR spectra were recorded on Bruker AM

Acknowledgements

We are grateful for financial support by the Deutsche Forschungsgemeinschaft and the Göttinger Akademie der Wissenschaften. H.W. is grateful to the Fonds der Chemischen Industrie for a fellowship.

References (21)

G Gundersen et al.
J. Organomet. Chem.
(1973)
V Krieg et al.
J. Organomet. Chem.
(1970)
H Grützmacher et al.
Angew. Chem.
(1991)
H Grützmacher et al.
Angew. Chem., Int. Ed. Engl.
(1991)
K Ziegler et al.
Angew. Chem.
(1955)
K Ziegler et al.
Liebigs Ann. Chem.
(1957)
A.W Laubengayer et al.
Inorg. Chem.
(1966)
H Lehmkuhl et al.
Chem. Ber.
(1968)
M Witt et al.
Curr. Sci.
(2000)
W Uhl et al.
Organometallics
(2001)
K Köhler et al.
Angew. Chem.
(1996)
K Köhler et al.
Angew. Chem., Int. Ed. Engl.
(1996)

There are more references available in the full text version of this article.

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Stepwise fluorination of [MeAlN(2,6-i-Pr2C6H3)]3 using trimethyltin fluoride as fluorinating agent

Abstract

Introduction

Section snippets

Results and discussion

Experimental

Acknowledgements

J. Organomet. Chem.

J. Organomet. Chem.

Angew. Chem.

Angew. Chem., Int. Ed. Engl.

Angew. Chem.

Liebigs Ann. Chem.

Inorg. Chem.

Chem. Ber.

Curr. Sci.

Organometallics

Angew. Chem.

Angew. Chem., Int. Ed. Engl.

Stepwise fluorination of [MeAlN(2,6-i-Pr₂C₆H₃)]₃ using trimethyltin fluoride as fluorinating agent