New anions of pentacoordinate phosphorus containing fluorine and trifluoromethyl groups

Article abstract of DOI:10.1002/ejic.200600974

The unique pseudo-trigonal-bipyramidal CF₃PF₃O ^- and (CF₃)₂PF₂O^- anions were obtained and characterised for the first time. They were formed by the reactions of (PhO)₃P(O), Me₃SiCF₃ and the fluoride ion sources [Me₄N]F and CsF, respectively, in glyme. These anions represent the stable transition states postulated for nucleophilic substitution at a tetrahedral phosphorus atom. The salt Cs[(CF₃) ₂PF₂O] (7) is stable at room temperature for a month, while [Me₄N][CF₃PF₃O] (1) dismutates into [Me₄N][CF₃PF(O)O] (2) and [Me₄N][CF ₃PF₅] (3) above 0°C. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200600974

FULL PAPER
DOI: 10.1002/ejic.200600974
New Anions of Pentacoordinate Phosphorus Containing Fluorine and
Trifluoromethyl Groups
Natalya V. Pavlenko,[a] Lesya A. Babadzhanova,[a] Igor I. Gerus,[b] Yurii L. Yagupolskii,*[a]
Wieland Tyrra,[c] and Dieter Naumann[c]
Dedicated to Professor Karl Otto Christe on the occasion of his 70th birthday
Keywords: Phosphorus / Fluorides / Silanes / Pentacoordinate anions
The unique pseudo-trigonal-bipyramidal CF3PF3O– and
(CF3)2PF2O– anions were obtained and characterised for the
first time. They were formed by the reactions of (PhO)3P(O),
Me3SiCF3 and the fluoride ion sources [Me4N]F and CsF,
respectively, in glyme. These anions represent the stable
transition states postulated for nucleophilic substitution at a
tetrahedral phosphorus atom. The salt Cs[(CF3)2PF2O] (7) is
stable at room temperature for month, while
[Me4N][CF3PF3O] (1) dismutates into [Me4N][CF3PF(O)O] (2)
and [Me4N][CF3PF5] (3) above 0 °C.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
a
Introduction
Results and Discussion
The importance of fluorinated compounds is rapidly in-
creasing in many fields of modern agrochemistry, pharma-
ceutical industry and material sciences.[1] During the past
several decades numerous methods were developed for the
direct introduction of fluorinated substituents, in particular
trifluoromethyl groups, into different types of molecules.
Among a wide variety of reagents for CF3 group introduc-
tion, commercially available trimethyl(trifluoromethyl)-
silane had become the reagent of choice.[2] However, only a
few phosphorus-containing electrophiles have been used for
nucleophilic trifluoromethylation with Me3SiCF3.[3]
Reactions of (PhO)3P(O) with Me3SiCF3 and [Me4N]F
The reactions of (PhO)3P(O) with Me3SiCF3 and [Me4N]F
yielded complex product mixtures. The composition
strongly depended on the stoichiometry of the starting ma-
terials, the solvent and the temperature. The conditions for
obtaining tetramethylammonium trifluoro(trifluorometh-
yl)phosphoranolate (1) as the major phosphorus-containing
compound were 4 equiv. [Me4N]F, 1 equiv. Me3SiCF3 and
1 equiv. (PhO)3P(O), with dme as the solvent and a tem-
perature of –40 °C (Scheme 1).
Salt 1 contains a unique anion that represents the stable
transition state usually postulated in the course of nucleo-
philic substitution at a tetrahedral phosphorus atom.[5]
Compound 1 is stable for a reasonable time, both in solu-
tion and in the solid state at temperatures equal to or below
0 °C. It presents one more example of hypervalent com-
pounds whose stability is significantly increased by the in-
troduction of perfluoroalkyl groups.
It has been shown that it is possible to convert PV–F
compounds into the corresponding PV–CF3 derivatives by
reactions of Me3SiCF3 in the presence of catalytic amounts
of F– sources.[3] In order to avoid the use of toxic phospho-
rous oxofluorides as starting materials and taking into ac-
count two examples of successful trifluoromethylation of
[3c]
aryl esters of PIII-acids by Me3SiCF3
and by Ruppert’s
method,[4] we investigated the reactions of triphenylphos-
phate and Me3SiCF3 in the presence of fluoride sources. It
should be noted in advance that the results differ from each
other depending on the initiator, [Me4N]F or CsF, and will
therefore be described separately.
The formation of the trifluoro(trifluoromethyl)phos-
phoranolate anion and its structure were established by
NMR spectroscopic and mass spectrometric data. NMR
spectra recorded at 20 °C are of first order and imply that
the anion appears to be rigid at this temperature (Figure 1,
Table 1).
[a] Institute of Organic Chemistry, National Academy of Sciences
of Ukraine,
5 Murmanskaya St., 02094 Kiev 94, Ukraine
[b] Institute of Bioorganic Chemistry and Petrochemistry, National
Academy of Sciences of Ukraine,
1 Murmanskaya St., 02094 Kiev 94, Ukraine
[c] Institut für Anorganische Chemie, Universität zu Köln,
Greinstrasse 6, 50939 Köln, Germany
The anion exhibits two signals in the 19F NMR spectrum
for the fluorine atoms attached to the phosphorus centre
with an integrative ratio of 1:2. The low-field doublet of
triplets (δ = –46.9 ppm) corresponds to the fluorine atom
2
in the axial position (1JF
= 812 Hz, JF
= 82 Hz),
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ax–P
ax–Feq
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Y. L. Yagupolskii et al.
FULL PAPER
Scheme 1.
and the doublet of doublets of quartets (δ = –65.2 ppm) is
assigned to two equatorial fluorine atoms (1JF
=
eq–P
2
3
1010 Hz, JF
= 82 Hz, JF
= 15 Hz). The signal
eq–Fax
eq–CF3
of the CF3 group is found at δ = –73.0 ppm and appears as
3
a doublet of triplets (2JCF –P = 100 Hz, JCF –F = 15 Hz).
3
3
eq
The chemical shift (δ Ͻ –70 ppm) of the CF3 group suggests
axial position in comparison with NMR spectroscopic data
of related compounds.[7] The triplet of doublets of quartets
(δ = –71.3 ppm) in the 31P NMR spectrum falls into the
shift range of pentacoordinate phosphorus[7,8] and proves
additionally that the anion contains two different types of
fluorine atoms and one CF3 group. Thus the anion of salt
1 has the structure of a trigonal bipyramid with one fluor-
ine atom and the trifluoromethyl group in axial positions
and two fluorine atoms and the oxygen atom in the equato-
rial plane. The 1H NMR spectrum shows only the signal of
the tetramethylammonium cation at δ = 2.95 ppm.
Salt 1 undergoes slow dismutation at temperatures above
0 °C, forming stable tetracoordinate and hexacoordinate
(compounds 2 and 3, respectively) phosphorus species
(Scheme 2). Therefore, NMR spectra could be run at ambi-
ent temperature.
Dismutation of salt 1 presumably proceeds with initial
formation of the (trifluoromethyl)phosphonyl difluoride
(A) by fluoride elimination; A reacts with the anion 1 to
form the second intermediate, the dimeric anion B. The
Figure 1. NMR spectra of [Me4N][CF3PF3O] (1) recorded in
CD3CN: (a) 31P spectrum (121.42 MHz) and (b) 19F spectrum
(282.41 MHz).
Table 1. Compilation of 19F and 31P NMR spectroscopic data of all synthesised compounds.
1
[a] The spectrum is of higher order (A3B4CX spin system). [b] 13C{19F} NMR (D2O): δ = 126.2 (d, JP–C = 422 Hz) ppm. [c] Cf. ref.[6]
1
[d] 13C{19F} NMR (D2O): δ = 122.3 (d, JP–C = 248 Hz) ppm.
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New Anions of Pentacoordinate Phosphorus
FULL PAPER
Scheme 2.
Scheme 3.
Scheme 4.
fluoride anion liberated in the first reaction step then at- as at 20 °C. The 19F- and 31P NMR spectra analysis ([D6]-
tacks the hexacoordinate phosphorus atom of intermediate dmso, room temperature) showed that the reaction mixture
B to give salts 2 and 3 as the final reaction products. Both contained tetrafluorophosphoranolate (4) as the major
salts were separated by fractional crystallisation and char- product and its dismutation products 5 and 6 as minor ones
acterised by NMR spectroscopic methods and elemental (Scheme 4).
analyses.
NMR investigations of 1:1 mixtures of (PhO)3P(O) and
It is explicitly noteworthy that the result of the reaction [Me4N]F at –70 °C gave no evidence for the key ion
between (PhO)3P(O), Me3SiCF3 and [Me4N]F provides a
[(PhO)3-
new method to obtain two important perfluoroalkyl-con- PFO]– but allowed the detection of (PhO)2P(O)F {δF (dme/
1
taining phosphorus anions, that is, fluoro(trifluoromethyl)- [D8]thf, v/v = 50:50, –40 °C) = –78.7 ppm, JF–P = 996 Hz;
phosphonate (in salt 2) and hard-to-prepare λ6-pentafluo- δP (dme/[D8]thf, v/v = 50:50, –40 °C) = –17.0 ppm, JF–P
=
1
ro(trifluoromethyl)phosphate (in salt 3).[9] The doubtless 996 Hz}[10] and its consecutive products 5, [(PhO)2P(O)O]–
advantages of this method are the good availability of the and [PhOPF(O)O]–.[11,12]
starting materials, the mild reaction conditions and the high
yields of the target products.
The characteristic NMR spectroscopic data for the com-
pounds 4, 5 (Table 1) and 6 are in full agreement with the
An equimolar mixture of salts 2 and 3 was also obtained data given by Christe et al.[8] The main advantage of the
by fluorination of (trifluoromethyl)phosphonyl dichloride [F4PO]– anion synthesis starting from triphenylphosphate is
with [Me4N]F (Scheme 3).
the relative stability of this anion in the solid state as well
However, in this case we were unable to isolate salt 1. It as in dmso solution at 20 °C. This result supports the
was only detected in the NMR spectra of the mixture to- suggestion that the presence of excess P(O)F3 used in the
gether with salts 2 and 3. This may be explained by the known procedure significantly accelerates the dismutation
initial formation of (trifluoromethyl)phosphonyl difluoride process.[8]
(A) which adds [Me4N]F to form salt 1. Similarly the dis-
mutation process starts as outlined earlier, analogous to the
elusive tetrafluorophosphate dismutation presented by
Reactions of (PhO)3P(O) with Me3SiCF3 and CsF
Christe et al.[8] The latter anion was obtained by F– ad-
dition to P(O)F3, and its composition was elucidated by
To our great surprise we were unable to obtain the Cs
NMR experiments performed at –140 °C. In one of our ex- analogue of salt 1 under the same reaction conditions using
periments, triphenylphosphate was treated with 4 equiv. CsF instead of [Me4N]F. The product of this reaction was
[Me4N]F in dme at –40 °C. All phosphorus-containing the pentacoordinate phosphorus anion difluorobis(trifluoro-
products were insoluble in dme at this temperature as well methyl)phosphoranolate, [(CF3)2PF2O]–, while reasonable
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Y. L. Yagupolskii et al.
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amounts of the starting material triphenylphosphate re-
Salt 7 is stable in dme or CH3CN solutions, as well as in
mained unchanged. Variation of the stoichiometry to the solid state for months at 20 °C, but it is extremely sensi-
3 equiv. CsF, 2 equiv. Me3SiCF3 and 1 equiv. (PhO)3P(O) tive to moisture. Also, storing the solid especially in glass-
led to a nearly pure solution of cesium difluorobis(trifluoro- ware causes decomposition into bis(trifluoromethyl)phos-
methyl)phosphoranolate (7) (Scheme 5).
phinic (8)[6,14] and (trifluoromethyl)phosphonic (10)[6,15] ac-
ids (Scheme 6).
The degradation of 7 can be explained on the assumption
of the intermediate formation of bis(trifluoromethyl)phos-
phinyl fluoride (C) which is hydrolysed either by replace-
ment of the fluorine atom or the trifluoromethyl group by
hydroxy groups. In the latter case, NMR spectroscopic evi-
dence was found for fluoro(trifluoromethyl)phosphonic
Scheme 5.
By comparison to the known structure[13] and NMR
spectroscopic data[7] of the closely related (CF3)2PF3 and
the easily interpretable 19F- and 31P NMR spectra of salt 7
on a first order basis (Figure 2, Table 1), we propose both
CF3 groups reside in axial positions, while the two fluorine
atoms and the oxygen atom are located in the equatorial
plane of a trigonal bipyramid.
1
acid (9) [δF (CD3CN) = –71.8 ppm (d, JF–P = 980 Hz),
2
–72.7 ppm (d, JF–P = 102 Hz); δP (CD3CN) = –8.8 ppm
1
2
(dq, JF–P = 980 Hz, JF–P = 102 Hz)] which is rapidly hy-
drolysed to acid 10.
In order to obtain the Cs analogue of salt 1, we per-
formed the reaction of (trifluoromethyl)phosphonyl dichlo-
ride with CsF (Scheme 7).
The triplet of septets in the range of pentacoordinate
phosphorus (δ = –64.9 ppm) in the 31P NMR spectrum
gives evidence that anion 7 contains two magnetically
equivalent fluorine atoms and two equivalent CF3 groups.
The 19F NMR spectrum exhibits the signal of two fluorine
atoms bonded to the phosphorus atom as a doublet of sep-
tets centred at δ = –75.0 ppm. Correspondingly, the signals
of the trifluoromethyl groups are split into doublets of trip-
The instability of 11 prevented its detection in NMR
spectra of the reaction mixture. Only an equimolar mixture
of the dismutation products, fluoro(trifluoromethyl)phos-
phonate 12 and λ6-pentafluoro(trifluoromethyl)phosphate
13 was obtained. The salts were separated by fractional
crystallisation, and both compounds were characterised. It
–
is noteworthy that salts with the anion CF3PF5 were re-
ported at the end of the 1960s,[9] but the NMR spectro-
scopic characterisation had remained insufficient until now.
The 19F- and 31P NMR spectroscopic data for salt 13 are
shown in Figure 3 (cf. Table 1).
2
lets centred at δ = –74.3 ppm with JCF –P = 113 Hz and
3
3JCF –F = 16 Hz. The high-field shifts of both signals, com-
3
eq
pared with values found for compounds with opposite ar-
rangement of the CF3 groups and the fluorine atoms,[7] as
well as the value of 1JF–P = 1080 Hz, indicate that the fluor-
ine atoms are located in the equatorial plane of the trigonal
bipyramid.
The 19F NMR spectrum of the Cs salt 13 is of higher
order; the calculated spectrum[16] for an A3B4CX spin sys-
tem matched well with the measured spectrum. While the
Figure 2. NMR spectra of Cs[(CF3)2PF2O] (7) recorded in CD3CN at 20 °C: (a) 31P spectrum (121.42 MHz) and (b) 19F spectrum
(282.41 MHz).
Scheme 6.
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New Anions of Pentacoordinate Phosphorus
FULL PAPER
Scheme 7.
Conclusions
Some general conclusions can be made thus far. Tetraco-
ordinate triphenylphosphate is converted into the highly
fluorinated pentacoordinate phosphorus derivatives 1 or 7
in the reaction with Me3SiCF3 and sources of fluoride. We
assume that the nucleophilic substitution at the tetrahedral
phosphorus atom follows the addition-elimination pro-
cess[5] and, as far as F– is in excess relative to the second
–
nucleophile “CF3 ”, the first step of the reaction is the ad-
dition of F– to the P=O bond of triphenylphosphate to give
intermediate D (Scheme 8) followed by spontaneous PhO–
elimination to give (PhO)2P(O)F.[10] The ease of adding
fluoride to tris(pentafluoroethyl)phosphane oxide[17] and
phosphoryl trifluoride[8] further supports this assumption.
Upon the substitution of the next PhO group, the highly
–
reactive “CF3 ” nucleophile can compete with the fluoride
anion, as is shown in the proposed reaction mechanism
(Scheme 8).
One of the facts that supports this scheme is that the
intermediate of type G (mixed with salt 1) was observed in
the NMR spectra of the reaction mixture with the reagent
ratio (PhO)3P(O)/Me3SiCF3/[Me4N]F = 1:2:1. This inter-
mediate is tetramethylammonium phenyl difluoro(trifluoro-
methyl)phosphonate (14) (Figure 4).
The NMR spectroscopic data (Table 1) allow us to pro-
pose the mentioned structure of this unstable anion.
We have characterised three compounds among the pos-
sible final structures of type H, namely the tetramethylam-
Figure 3. NMR spectra of Cs[CF3PF5] (13) recorded in D2O at
20 °C: (a) 31P spectrum (202.45 MHz) and (b) 19F spectrum
(470.54 MHz).
signals for the fluorine atoms directly bonded to phospho- monium salt of the tetrafluorophosphoranolate ion (4), salt
rus appear as doublets of complex multiplets (δF 1 with one trifluoromethyl group and salt 7 with two tri-
=
ax
–72.9 ppm, δF = –73.9 ppm), the signal of the CF3 group fluoromethyl groups attached to the phosphorus atom. The
eq
(δ = –69.5 ppm) can be interpreted as a “first order” doub- stability of anions of type H increases significantly in the
–
–
–
let (2JCF –P = 140 Hz) of quintets (3JCF –F = 13 Hz) of series POF4 Ͻ CF3POF3 Ͻ (CF3)2POF2 , but their solu-
doublets3(3JCF –F = 2.5 Hz). The doublet eqof quintets of bility in organic solvents changes in the reverse order. The
3
3
ax
quartets in the 31P NMR spectrum unambiguously con- solvent plays a key role in the investigated reactions; dme
firms the predicted octahedral structure of the anion.
is the best choice allowing selective reactions, whereas mix-
Scheme 8.
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31P NMR spectra showed complete disappearance of a multiplet at
δ = –71 ppm (≈ 8 h). The solvent was removed in vacuo, and the
residue was extracted with hot dme (3ϫ10 mL). The solvent was
reduced to about 10 mL. After storage of the resultant solution at
–17 °C overnight, colourless crystals unsuitable for XRD measure-
ments of 2 were obtained. Yield: 0.13 g (78%). M.p. 110–113 °C
(dec.). 1H NMR (D2O): δ = 2.93 (s, NCH3) ppm. C5H12F4NO2P
(225.15): calcd. C 26.67, H 5.37, N 6.22; found C 26.35, H 5.72, N
6.13. The residue after extraction was recrystallised from MeCN to
Figure 4. Tetramethylammonium phenyl difluoro(trifluoromethyl)-
phosphonate (14).
1
give salt 3. Yield: 0.18 g (86%). M.p. 263–266 °C (dec.). H NMR
(D2O): δ = 2.89 (s, NCH3) ppm. C5H12F8NP (269.15): calcd. C
22.31, H 4.49, N 5.20; found C 22.15, H 4.53, N 5.13.
tures are formed in thf, and no reaction is observed in ether
or propionitrile. The distinct difference in the results de-
pending on whether [Me4N]F or CsF is used as a fluoride
source is probably a result of their different solubility in
dme. The less soluble CsF provides a lower concentration
of fluoride in solution, and consequently the possibility of
the substrate reacting with the competitive nucleophile
Fluorination of (Trifluoromethyl)phosphonyl Dichloride with Tetra-
methylammonium Fluoride: To a solution of CF3P(O)Cl2 (0.50 g,
2.67 mmol) in dme (10 mL) at –40 °C was added [Me4N]F (0.77 g,
8.27 mmol) in small portions over a period of 15 min. The resulting
mixture was stirred for 2 h at this temperature and was then
warmed slowly (≈ 4 h) to 0 °C. Stirring was continued at this tem-
perature for 30 min, and the precipitate was filtered off. 19F- and
31P NMR spectra of the resultant filtrate showed the presence of
compounds 1, 2 and 3 in a ratio of approximately 2:4:3. The solu-
tion was kept at room temp. overnight to complete the dismutation
of compound 1. The solvent was removed in vacuo. The reaction
mixture was worked up in the same manner as described earlier.
After purification, compounds 2 and 3 were obtained in yields of
72% (0.22 g) and 53% (0.19 g), respectively. Some part of the less
soluble salt 3 precipitated together with [Me4N]Cl. Extraction of
the primary precipitate with hot MeCN yielded more compound 3
(0.10 g) giving a total yield of compound 3 of 0.29 g (81%).
–
“CF3 ” is favoured. The result is the formation of salt 7
containing two trifluoromethyl groups. It is noteworthy that
we have never observed an anion with three CF3 groups
bonded to the phosphorus atom even when using a high
excess of trimethyl(trifluoromethyl)silane relative to the
fluoride source.
Experimental Section
General: All reactions were carried out under argon, using Schlenk
type glassware with rigorous exclusion of traces of moisture and
air. The solvents were purified by standard methods and were con-
densed in vacuo prior to use. Me3SiCF3 was purchased from
ABCR. [Me4N]F[18] and CF3P(O)Cl2[19] were synthesised according
to literature procedures. [Me4N]F and CsF were carefully dried in
vacuo directly before use. Room temp. 1H-, 19F-, 31P- and 13C
NMR spectra were recorded with either a Varian VXR-300 or a
Bruker Avance II 300 spectrometer and in one case (salt 13) with
a Bruker Avance DRX 500 spectrometer. Low-temperature NMR
experiments were performed with a Bruker AC 200 spectrometer.
Chemical shifts are given in ppm relative to Me4Si as internal and
CCl3F and 85% H3PO4 as external standards. The NMR spectro-
scopic data are compiled in Table 1. Negative ESI mass spectra
were recorded with a Finnigan MAT 900 apparatus with a flow
rate of 2 µL/min. Intensities are referenced to the most intense peak
of a group.
Cesium Difluorobis(trifluoromethyl)phosphoranolate (7): To a solu-
tion of triphenylphosphate (0.60 g, 1.84 mmol) and trimethyl(tri-
fluoromethyl)silane (0.55 g, 3.87 mmol) in dme (10 mL) at –40 °C
was added CsF (0.84 g, 5.53 mmol) in small portions over a period
of 15 min. The resulting mixture was stirred for 2 h at this tempera-
ture and was then warmed slowly to room temp. Stirring was con-
tinued overnight, the precipitated solid was filtered off, and the
solvent was removed in vacuo. The residue was washed with ben-
zene (3ϫ5 mL), filtered and dried in vacuo to give salt 7. Yield:
0.31 g (48%). M.p. 73–75 °C (dec.). Because of the extreme moist-
ure sensitivity of compound 7, we were unable to obtain satisfac-
tory elemental analytical data. Negative ESI-MS (MeCN): m/z (%)
= 223 (100) [(CF3)2PF2O]–.
Fluorination of (Trifluoromethyl)phosphonyl Dichloride with Cesium
Fluoride: To a solution of CF3P(O)Cl2 (0.40 g, 2.14 mmol) in dme
(10 mL) at –40 °C was added CsF (0.99 g, 6.52 mmol) in small por-
tions over a period of 15 min. The mixture was stirred for 2 h at
this temperature and was then warmed to room temp. Stirring was
continued overnight, the solvent was removed in vacuo, and the
residue was extracted with hot MeCN (50 mL). After storing the
solution at –17 °C, the precipitate was filtered off and recrystallised
from a 10:1 (v/v) dioxane/water mixture to yield the pure salt 13 as
colourless crystals unsuitable for XRD measurements. Yield: 0.31 g
(87%). CCsF8P (327.89): calcd. C 3.66, P 9.45; found C 3.57, P.
9.52. 19F- and 31P NMR spectra of the resultant filtrate showed
the presence of salt 12 (Table 1) as the major product (Ͼ70%). This
compound was not fully characterised because of its high sensitiv-
ity to moisture.
Tetramethylammonium Trifluoro(trifluoromethyl)phosphoranolate
(1): To a solution of triphenylphosphate (0.60 g, 1.84 mmol) and
trimethyl(trifluoromethyl)silane (0.32 g, 2.25 mmol) in dimethoxy-
ethane (dme) (10 mL) at –40 °C was added [Me4N]F (0.69 g,
7.42 mmol) in small portions over a period of 15 min, and the re-
sulting mixture was stirred for 2 h at this temperature and was then
warmed slowly (≈ 4 h) to 0 °C. Stirring was continued at this tem-
perature for 30 min, and the white precipitate was immediately fil-
tered. The solvent was removed in vacuo, and the residue was sus-
pended in diethyl ether (≈ 5 mL) at 0 °C, filtered and dried in vacuo
at this temperature to give salt 1. Yield: 0.38 g (82%). 1H NMR
(CD3CN): δ = 2.95 (s, NCH3) ppm. Negative ESI-MS (MeCN):
m/z (%) = 151 (20) [CF3(F)P(O)O]–, 173 (100) [CF3PF3O]–, 223
(68) [(CF3)2PF2O]–, 225 (45) [CF3P(O)(OPh)O]–. Note: Care has to
be taken that the operations are performed as quickly as possible
to avoid decomposition.
Acknowledgments
The Dismutation Reaction of Compound 1: The solution of 1
Generous financial support of this work by the Deutsche For-
(0.38 g, 1.54 mmol) in MeCN (10 mL) was kept at room temp. until schungsgemeinschaft is gratefully acknowledged (436 UKR 113/
1506 Eur. J. Inorg. Chem. 2007, 1501–1507
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New Anions of Pentacoordinate Phosphorus
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