D e s c r i p t i o n

The following invention relates to the activation and degradation of Sulfurhexaflouride, SF ₆ .

Although sulfur hexafluoride SF ₆ has been recognized as the most potent greenhouse gas in the atmosphere, it is widely used in a variety of industrial applications and processes owing to its unique physical and chemical properties such as a high dielectric constant, low toxicity and its extreme chemical inertness. The 100 year global warming potential of SF ₆ is 23500 times higher than that of C0 ₂ as a result of its high radiative efficiency and long atmospheric lifetime of about 3200 years. Therefore, safe and efficient methods for its depletion are required. Typical technical methods include electrical or plasma discharge technologies, which not only suffer from the high energy consumption, but also yield especially toxic and corrosive decomposition products, cf. Zamostna and Braun, Nachrichten aus der Chemie 2016, 829-835. Therefore there is a constant need for methods for the degradation and/or activation of SF ₆ and it is an object to provide alternative methods which idealiter can be performed under mild conditions and possibly lead to products which have commercial and/or chemical interest. This object is solved by the method of Claim 1. Accordingly a method for the activation and/or degradation of SF ₆ is provided comprising the step of contacting SF ₆ with a phosphine PR ^X R ² R ³ , whereby at least one of the R ¹ to R ³ is a moiety which has π-donating

characteristics.

The term "π-donating characteristics" in the sense of the present invention especially means that the atom in a-position to the phosphorus atom of the phosphine has at least one lone pair of electrons that can donate electron density towards the phosphorus atom thus increasing the phoshine's basicity. The moiety which has π-donating characteristics can according to a preferred embodiment be neutral or the moiety which has π-donating characteristics can according to a preferred embodiment be anionic.

Surprisingly it has been found that these compounds are able to react with SF ₆ . For most applications within the present invention at least one or more of the following advantages can be observed:

- The reaction occurs at low temperatures, starting from -78°C or at room temperature

The reaction is very fast

The reaction does not require any additional activation

The reaction is quantitative with respect to the SF ₆

The reaction products are of chemical interest

- The reaction products can be used as fluorinating agents in chemical synthesis

The reaction products are temperature- stable solids

The reaction products are non-toxic

The inventors have found that the degradation of the SF ₆ in most applications follows one of the following two reaction pathways: a) Formation of two reaction products, i.e. P(=S)R ¹ R ² R ³ and PR ¹ R ² R ³ F ₂ .

b) Formation of the salt PR^R^ ^"1" SF ₅ ^" which is in most applications isolatable. It has been found that pathway a) more likely occurs when not all of the R ¹ to R ³ have a π- donating characteristics, whereas when all of the R ¹ to R ³ have a π-donating characteristics in many cases pathway b) is followed. As stated above, the reaction products are of chemical and/or commercial interest since they can be used as fluorine donor in suitable applications. Moreover, since ¹⁸ F- substituted sulfurhexafluoride is commercially available, the inventive degradation process offers the possibility to synthesize ¹⁸ F-labeled chemical compounds which are of high interest, e.g. in pharmaceutical and medical applications such as positron-emission tomography (PET) imaging.

According to a preferred embodiment of the present invention, the phosphine does not form a part of a metal complex and/or is not a ligand to a metal during the activation and/or degradation of SF ₆ .

According to a preferred embodiment of the present invention, the phosphine does not form a part of a Rhodium complex and/or is not a ligand to Rhodium during the activation and/or degradation of SF ₆ . So it is a further object of the present invention to provide new fluorinating and/or fluor- donating products obtainable from SF ₆ .

Accordingly PR ¹ R ² R ³ F ⁺ SF ₅ ^" and PR ¹ R ² R ³ F ₂ are provided with R ¹ to R ³ as defined in this invention.

The present invention also relates to the use of PR ¹ R ² R ³ F ⁺ SF ₅ ^" and/or PR ¹ R ² R ³ F ₂ in fluorination reactions According to a preferred embodiment the moiety which has π-donating characteristics comprises a structure -A-B with

A = :N-¾- .C-¾-

^• · R

with R ⁴ , R ⁵ , R ⁸ , R ¹⁶ being selected independently from each other hydrogen, alkyl, long- chain alkyl, alkenyl, cycloalkyl, alkoxy, long chain alkoxy, alkylene, aryl, arylene, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, and with R ⁶ , R ⁷ , R ⁹ to R ¹⁵ being selected independently from each other hydrogen, alkyl, long-chain alkyl, alkenyl, cycloalkyl, alkoxy, long chain alkoxy, alkylene, aryl, arylene, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, dialkylamine, whereby two suitable substituents may form a ring, especially an aromatic ring.

According to a preferred alternative embodiment the moiety which has π-donating

characteristics comprises a structure -A-B with

with M ⁺ being selected from alkali and Mg-Halogenide, R ¹⁷ and R ¹⁸ being selected independently from each other hydrogen, alkyl, long-chain alkyl, alkenyl, cycloalkyl, alkoxy, long chain alkoxy, alkylene, aryl, arylene, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, dialkylamine whereby two suitable substituents may form a ring, especially an aromatic ring.

Generic group definition: Throughout the description and claims generic groups have been used, for example alkyl, alkoxy, aryl. Unless otherwise specified the following are preferred groups that may be applied to generic groups found within compounds disclosed herein: alkyl: linear and branched Cl-C8-alkyl, long-chain alkyl: linear and branched C5-C20 alkyl alkenyl: C2-C6-alkenyl, cycloalkyl: C3-C8-cycloalkyl, alkoxy: Cl-C6-alkoxy, long-chain alkoxy: linear and branched C5-C20 alkoxy alkylene: selected from the group consisting of:

methylene; 1,1-ethylene; 1,2-ethylene; 1,1 -prop ylidene; 1,2-propylene; 1,3- propylene; 2,2- propylidene; butan-2-ol-l,4-diyl; propan-2-ol-l,3-diyl; 1, 4-butylene; cyclohexane- 1,1 -diyl; cyclohexan-l,2-diyl; cyclohexan-1,3- diyl; cyclohexan-l,4-diyl; cyclopentane- 1,1 -diyl; cyclopentan-l,2-diyl; and cyclopentan-l,3-diyl, aryl: selected from homoaromatic compounds having a molecular weight under 300, arylene: selected from the group consisting of: 1,2-phenylene; 1,3- phenylene; 1,4-phenylene;

1.2- naphtalenylene; 1,3-naphtalenylene; 1,4- naphtalenylene; 2,3-naphtalenylene; 1-hydroxy-

2.3- phenylene; l-hydroxy-2,4- phenylene; l-hydroxy-2,5- phenylene; and l-hydroxy-2,6- phenylene, heteroaryl: selected from the group consisting of: pyridinyl; pyrimidinyl; pyrazinyl; triazolyl; pyridazinyl; 1,3,5-triazinyl; quinolinyl; isoquinolinyl; quinoxalinyl; imidazolyl; pyrazolyl; benzimidazolyl; thiazolyl; oxazolidinyl; pyrrolyl; carbazolyl; indolyl; and isoindolyl, wherein the heteroaryl may be connected to the compound via any atom in the ring of the selected heteroaryl, heteroarylene: selected from the group consisting of: pyridindiyl; quinolindiyl; pyrazodiyl; pyrazoldiyl; triazolediyl; pyrazindiyl; and imidazolediyl, wherein the heteroarylene acts as a bridge in the compound via any atom in the ring of the selected heteroarylene, more specifically preferred are: pyridin-2, 3-diyl; pyridin-2,4-diyl; pyridin-2,5-diyl; pyridin-2,6- diyl; pyridin-3,4- diyl; pyridin-3,5-diyl; quinolin-2,3-diyl; quinolin-2,4-diyl; quinolin-2, 8- diyl; isoquinolin-1, 3-diyl; isoquinolin-l,4-diyl; pyrazol-1, 3-diyl; pyrazol-3,5- diyl; triazole- 3,5-diyl; triazole-1, 3-diyl; pyrazin-2,5-diyl; and imidazole-2,4-diyl, a -C1-C6- heterocycloalkyl, wherein the heterocycloalkyl of the -CI -C6-heterocycloalkyl is, selected from the group consisting of: piperidinyl; piperidine; 1,4-piperazine, tetrahydrothiophene; tetrahydrofuran; 1,4,7-triazacyclononane; 1,4,8,11- tetraazacyclotetradecane; 1,4,7,10,13- pentaazacyclopentadecane; 1,4-diaza- 7-thia-cyclononane; 1,4- diaza-7-oxa-cyclononane; 1,4,7, 10-tetraazacyclododecane; 1,4-dioxane; 1,4, 7-trithia-cyclononane; pyrrolidine; and tetrahydropyran, wherein the heterocycloalkyl may be connected to the -Cl-C6-alkyl via any atom in the ring of the selected heterocycloalkyl, heterocycloalkylene: selected from the group consisting of: piperidin-1,2- ylene; piperidin- 2,6-ylene; piperidin-4,4-ylidene; l,4-piperazin-l,4-ylene; l,4-piperazin-2,3-ylene; 1,4- piperazin-2,5-ylene; l,4-piperazin-2,6-ylene; 1,4-piperazin- 1,2-ylene; l,4-piperazin-l,3- ylene; l,4-piperazin-l,4-ylene; tetrahydrothiophen-2,5-ylene; tetrahydrothiophen-3,4-ylene; tetrahydrothiophen-2,3-ylene; tetrahydrofuran-2,5-ylene; tetrahydrofuran- 3,4-ylene;

tetrahydrofuran-2,3-ylene; pyrrolidin-2,5-ylene; pyrrolidin-3,4-ylene; pyrrolidin-2,3-ylene; pyrrolidin- 1,2- ylene; pyrrolidin-l,3-ylene; pyrrolidin-2,2-ylidene; l,4,7-triazacyclonon-l,4- ylene; 1,4,7- triazacyclonon-2,3-ylene; l,4,7-triazacyclonon-2,9-ylene; 1,4,7-triazacyclonon- 3,8-ylene; l,4,7-triazacyclonon-2,2- ylidene; 1,4,8,1 l-tetraazacyclotetradec-l,4-ylene;

1,4,8,11- tetraazacyclotetradec-l,8-ylene; 1,4,8,1 l-tetraazacyclotetradec-2,3-ylene; 1,4,8,11- tetraazacyclotetradec-2,5-ylene; 1,4,8,11- tetraazacyclotetradec-l,2-ylene; 1,4,8,11- tetraazacyclotetradec-2,2-ylidene; 1 ,4,7, 10-tetraazacyclododec- 1 ,4-ylene; 1 ,4,7, 10- tetraazacyclododec-l,7-ylene; 1,4,7,10-tetraazacyclododec- 1,2- ylene; 1,4,7,10- tetraazacyclododec-2,3- ylene; 1,4,7, 10-tetraazacyclododec-2,2-ylidene; 1,4,7,10,13 pentaazacyclopentadec-l,4-ylene; 1,4,7,10,13- pentaazacyclopentadec-l,7-ylene; 1,4,7,10,13- pentaazacyclopentadec-2,3- ylene; 1,4,7, 10, 13-pentaazacyclopentadec-l,2-ylene; 1,4,7,10, 13-pentaazacyclopentadec-2,2-ylidene; l,4-diaza-7-thia-cyclonon- 1,4-ylene; l,4-diaza-7- thia-cyclonon-l,2-ylene; l,4-diaza-7thia-cyclonon- 2,3-ylene; l,4-diaza-7-thia-cyclonon-6,8- ylene; l,4-diaza-7-thia-cyclonon- 2,2-ylidene; l,4-diaza-7-oxacyclonon- 1,4-ylene; 1,4-diaza-

7- oxa-cyclonon- 1,2-ylene; l,4diaza-7-oxa-cyclonon-2,3-ylene; l,4-diaza-7-oxa-cyclonon-6,

8- ylene; l,4-diaza-7-oxa-cyclonon-2,2-ylidene; l,4-dioxan-2,3-ylene; 1,4- dioxan-2,6-ylene; 1 ,4-dioxan-2,2-ylidene; tetrahydropyran-2,3-ylene; tetrahydropyran-2,6-ylene;

tetrahydropyran-2,5-ylene; tetrahydropyran-2,2- ylidene; l,4,7-trithia-cyclonon-2,3-ylene; l,4,7-trithia-cyclonon-2,9- ylene; and l,4,7-trithia-cyclonon-2,2-ylidene, heterocycloalkyl: selected from the group consisting of: pyrrolinyl; pyrrolidinyl; morpholinyl; piperidinyl; piperazinyl; hexamethylene imine; 1,4-piperazinyl; tetrahydrothiophenyl;

tetrahydrofuranyl; 1,4,7- triazacyclononanyl; 1,4,8, 11 -tetraazacyclotetradecanyl; 1,4,7,10,13- pentaazacyclopentadecanyl; l,4-diaza-7-thiacyclononanyl; l,4-diaza-7-oxa- cyclononanyl; 1,4,7, 10-tetraazacyclododecanyl; 1,4-dioxanyl; 1,4,7- trithiacyclononanyl; tetrahydropyranyl; and oxazolidinyl, wherein the heterocycloalkyl may be connected to the compound via any atom in the ring of the selected heterocycloalkyl. Unless otherwise specified the following are more preferred group restrictions that may be applied to groups found within compounds disclosed herein: alkyl: linear and branched Cl-C6-alkyl, more preferred methyl, ethyl, propyl, isopropyl, buyl, isobutyl long-chain alkyl: linear and branched C5-C10 alkyl, preferably linear C6-C8 alkyl alkenyl: C3-C6-alkenyl, cycloalkyl: C6-C8-cycloalkyl, alkoxy: Cl-C4-alkoxy, long-chain alkoxy: linear and branched C5-C10 alkoxy, preferably linear C6-C8 alkoxy alkylene: selected from the group consisting of: methylene; 1,2-ethylene; 1,3-propylene; butan-2-ol-l,4-diyl; 1,4-butylene; cyclohexane-l,l-diyl; cyclohexan-l,2-diyl; cyclohexan-1,4- diyl; cyclopentane-l,l-diyl; and cyclopentan-l,2-diyl, aryl: selected from group consisting of: phenyl; biphenyl; naphthalenyl; anthracenyl; and phenanthrenyl, arylene: selected from the group consisting of: 1,2-phenylene; 1,3- phenylene; 1,4-phenylene; 1,2-naphtalenylene; 1,4-naphtalenylene; 2,3- naphtalenylene and l-hydroxy-2,6-phenylene, heteroaryl: selected from the group consisting of: pyridinyl; pyrimidinyl; quinolinyl; pyrazolyl; triazolyl; isoquinolinyl; imidazolyl; and oxazolidinyl, wherein the heteroaryl may be connected to the compound via any atom in the ring of the selected heteroaryl, heteroarylene: selected from the group consisting of: pyridin

2.3- diyl; pyridin-2,4-diyl; pyridin-2,6-diyl; pyridin-3,5-diyl; quinolin-2,3-diyl; quinolin-2,4- diyl; isoquinolin-l,3-diyl; isoquinolin-l,4-diyl; pyrazol-3,5-diyl; and imidazole-2,4-diyl, heterocycloalkyl: selected from the group consisting of:

pyrrolidinyl; morpholinyl; piperidinyl; piperidinyl; 1,4 piperazinyl; tetrahydrofuranyl; 1,4,7- triazacyclononanyl; 1,4,8,11-tetraazacyclotetradecanyl; 1,4,7,10,13- pentaazacyclopentadecanyl; 1,4,7, 10-tetraazacyclododecanyl; and piperazinyl, wherein the heterocycloalkyl may be connected to the compound via any atom in the ring of the selected heterocycloalkyl, heterocycloalkylene: selected from the group consisting of:

piperidin-2,6-ylene; piperidin-4,4-ylidene; l,4-piperazin-l,4-ylene; l,4-piperazin-2,3-ylene;

1.4- piperazin-2,6-ylene; tetrahydrothiophen-2,5-ylene; tetrahydrothiophen-3,4-ylene;

tetrahydrofuran-2,5-ylene; tetrahydrofuran-3,4-ylene; pyrrolidin-2,5-ylene; pyrrolidin-2,2- ylidene; l,4,7-triazacyclonon-l,4- ylene; l,4,7-triazacyclonon-2,3-ylene; 1,4,7- triazacyclonon-2,2-ylidene; 1,4,8,11- tetraazacyclotetradec-l,4-ylene; 1,4,8,11- tetraazacyclotetradec-l,8-ylene; 1,4,8,1 l-tetraazacyclotetradec-2,3-ylene; 1,4,8,11- tetraazacyclotetradec-2,2-ylidene; 1 ,4,7, 10-tetraazacyclododec- 1 ,4-ylene; 1 ,4,7, 10- tetraazacyclododec- 1 ,7-ylene; 1 ,4,7,10-tetraazacyclododec-2,3-ylene; 1 ,4,7 , 10- tetraazacyclododec-2,2-ylidene; 1,4,7,10,13- pentaazacyclopentadec-l,4-ylene; 1,4,7,10,13- pentaazacyclopentadec-l,7-ylene; l,4-diaza-7-thia-cyclonon-l,4 ylene; l,4-diaza-7-thia- cyclonon-2,3-ylene; l,4-diaza-7-thia cyclonon-2,2-ylidene; l,4-diaza-7-oxa-cyclonon-l,4- ylene; 1,4 diaza-7-oxa-cyclonon-2,3-ylene;l,4-diaza-7-oxa-cyclonon-2,2- ylidene; 1,4- dioxan-2,6-ylene; l,4-dioxan-2,2-ylidene; tetrahydropyran-2,6-ylene; tetrahydropyran-2,5- ylene; and tetrahydropyran- 2,2-ylidene, a -Cl-C6-alkyl-heterocycloalky, wherein the heterocycloalkyl of the -CI- C6-heterocycloalkyl is selected from the group consisting of: piperidinyl; 1,4-piperazinyl; tetrahydrofuranyl; 1,4,7- triazacyclononanyl; 1,4,8,11- tetraazacyclotetradecanyl; 1,4,7,10,13- pentaazacyclopentadecanyl; 1,4,7,10- tetraazacyclododecanyl; and pyrrolidinyl, wherein the heterocycloalkyl may be connected to the -C1-C6- alkyl via any atom in the ring of the selected heterocycloalkyl,

According to a preferred embodiment of the present invention, the moiety which has π- donating characteristics is selected out of amido groups, carbanions, oxido group or out of the neutral groups comprising imidazol-2-ylidenamino groups, imidazolin-2-ylidenamino groups, imidazolidin-2-ylidenamino groups, benzimidazolin-2-ylidenamino groups, imidazolin-4- ylidenamino groups, imidazol-2-ylidenmethyl groups, imidazolin-2-ylidenmethyl groups, imidazolidin-2-ylidenmethyl groups, benzimidazolin-2-ylidenmethyl groups, imidazolin-4- ylidenmethyl groups, pyridine-2-ylidenamino groups, pyridine-4-ylidenamino groups, pyridine-2-ylidenmethyl groups, pyridine-4-ylidenmethyl groups, phosphoranylidenamino groups, phosphoranylidenmethyl groups and mixtures thereof.

According to a preferred embodiment of the present invention, the moiety which has π- donating characteristics comprises imines.

In the sense of the present invention, the term "imine" especially means and/or includes the structure -N=X with X being further substituted carbon and/or phosphorus. It should be noted that not all of the possible compounds which fall under that definition are usually called imines, however, in the sense of the present invention, they may especially be regarded as imines, too.

Especially preferred are imines in which the carbon is part of a six-membered heterocyclic ring comprising at least one nitrogen. In this regard it is especially advantageous if the carbon is in 2- or 4-position to a nitrogen.

According to a preferred embodiment of the present invention, the moiety which has π- donating characteristics comprises imidazolimines. In the sense of the present invention the term "imidazolimines" especially means and/or includes the structure

whereby R ⁴ and R ⁵ are selected from the group comprising hydrogen, aryl and alkyl and whereby R ⁷ and R ⁸ may form a ring, especially an aromatic ring. The bond between the carbon atoms at R ⁶ and R ⁷ may be a single or a (at least formal) double bond.

According to a preferred embodiment, all three of the R ¹ to R ³ have has π-donating characteristics. In this case it is especially preferred that R ¹ to R ³ are identical.

However, the present invention is not limited to that and according to a preferred embodiment of the present invention at least one of the R ¹ to R ³ does not have π-donating characteristics. In this case especially alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups or dialkylamino groups are preferred as substituents bound to phosphorus.

It should be noted that according to a preferred embodiment of the present invention, the phosphine is not isolated before it is contacted with the SF ₆ . It has been shown that for many applications within the present invention this is not necessary for degradation of the SF ₆ .

According to a preferred embodiment, the inventive method is carried out at a temperature between > -78°C and < 60°C, preferably > 20°C and < 30°C, more preferred at room temperature. According to a preferred embodiment, the inventive method is carried out in a solvent. The solvent is preferably a non-protic organic solvent, more preferred THF, DMF, acetonitrile, benzene, toluene, m-xylene, hexane, pentane, heptane, cyclohexane, 1,4-dioxane, diethyl ether, Ethyl acetate or mixtures thereof.

Alternatively the inventive method is carried out with the phosphine applied on a solid carrier. This especially allows the reaction to occur in a flow-through fashion without the need for a solvent. Possible solid carrier materials include silica zeolites, diatomaceous earth, silicon dioxide (silica), aluminium oxide (alumina), carbon and mixtures thereof.

In case the inventive method is carried out with the phosphine applied on a solid carrier it is especially preferred that before the gas which is to be cleaned from SF ₆ before reaching the phosphine is removed from water and/or oxygen and/or C0 ₂ since these compounds also often react with the phosphine. This can be achieved by known methods in the art, e.g. by passing the gas through molecular sieves or a charcoal filter.

The aforementioned components, as well as the claimed components and the components to be used in accordance with the invention in the described embodiments, are not subject to any special exceptions with respect to their size, shape, material selection and technical concept such that the selection criteria known in the pertinent field can be applied without limitations.

Additional details, characteristics and advantages of the object of the invention are disclosed in the subclaims and the following description of the respective examples and embodiments— which in an exemplary fashion— show preferred embodiments according to the invention. Such examples do not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention as claimed.

EXAMPLE I:

Isolation of:

(Compound 1)

A solution of P(NI Pr) ₃ (465 mg, 757,4 mmol) in diethyl ether (10 mL) was pressurized with 2 bar sulfur hexafluoride pressure for 45 minutes. The crystalline component was filtered off and the crystals were washed with diethyl ether (3 x 3 mL). The filtrate was evaporated to dryness. Compound 1 was isolated as a crystalline solid in 92% yield. 1 showed good solubility and stability in acetonitrile, THF, dichloromethane, chloroform and

difluorobenzene. 1 is insoluble in benzene, toluene, hexane or diethyl ether. An NMR analysis revealed that solid 1 is stable at temperatures up to 145 °C and slowly decomposed at temperatures higher than 150 °C. No decomposition took place upon storage of 1 under argon atmosphere for 4 months. After exposure of solid 1 to air for one hour decomposition was detected in the NMR spectra.

EXAMPLE II: In the following SF ₆ was allowed to react with a phosphine having two imidazolimine and one isopropyl substituents according to the following reaction:

The NMR study to verify the degradation of sulfur hexafluoride with the phosphine was performed in C6D ₆ under 1 bar SF ₆ pressure. After 36 h at room temperature complete conversion of phosphine could be observed. The two resonances in the ³¹ P NMR spectrum for the phosphine sulfide (45.4 ppm, 16 Hz) and the difluorophosphoran (-59.2 ppm; t,

^PF = 606.0 Hz) verify the clean degradation of SF ₆ into two species. The resonance for the difluorophosphoran (-32.5 ppm; d, ^PF = 606.0 Hz) was also identified in the ¹⁹ F NMR spectrum.

EXAMPLE III:

In the following SF ₆ was allowed to react with a phosphine having three benzimidazolimine substituents according to the following reaction:

The NMR study to verify the degradation of sulfur hexafluoride with the phosphine was performed in THF-Ds under 1 bar SF ₆ pressure. After 48 h at room temperature complete conversion of phosphine could be observed. The two resonances in the ³¹ P NMR spectrum for the phosphine sulfide (20.6 ppm) and the difluorophosphoran (-87.3 ppm; t, ^PF = 570 Hz) verify the clean degradation of SF ₆ into two species. The resonance for the

difluorophosphoran (-12.8 ppm; d, ^PF = 570.0 Hz) was also identified in the ¹⁹ F NMR spectrum. EXAMPLE IV:

In the following SF ₆ was allowed to react with an in situ formed phosphine having three pyridine-4-imine substituents according to the following reaction:

Phosphorus trichloride (0.6 mL, 6.84 mmol) was added dropwise to a stirring solution of 1- butylpyridine-4-imine (5.238 g, 34.86 mmol) in THF (50 mL) at 0 °C and the stirred reaction mixture was allowed to warm to room temperature. Conversion was monitored via ³¹ P NMR spectroscopy from the reaction mixture. At room temperature KHMDS (4.093 g, 20.25 mmol) was added and the reaction mixture was stirred for 1 h at room temperature. The conversion was monitored via ³¹ P NMR spectroscopy of the reaction mixture. The volatiles were removed in vacuo at 40 °C and THF (20 mL) was added to the residue. The solution was frozen in liquid nitrogen and the argon atmosphere was removed in vacuo. After warming the solution to room temperature the Schlenk-flask was pressurized with 1 bar sulfur

hexafluoride. The immediate precipitation of a yellow solid was observed. For NMR spectroscopic analysis the THF was removed in vacuo and the products were dissolved in acetonitrile. The two resonances in the ³¹ P NMR spectrum for the phosphine sulfide (45.1 ppm) and the fluorophosphonium (15.8 ppm; t, ¹ JPF = 951.0 Hz) verify the clean degradation of SF ₆ into these two species. The resonance for the fluorophosphonium (-69.0 ppm; d, ¹ JPF = 951.0 Hz) was clearly identified in the F NMR spectrum as well as the [F-D-F] anion (-149 ppm, ² /DF = 18.0 Hz).

The particular combinations of elements and features in the above detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the patents/applications incorporated by reference are also expressly contemplated. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the foregoing description is by way of example only and is not intended as limiting. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The invention's scope is defined in the following claims and the equivalents thereto. Furthermore, reference signs used in the description and claims do not limit the scope of the invention as claimed.