Phosphinodefluorination of polyfluorobenzenes by silylphosphines Ph(R)PSiMe3 (R = Me, Ph): Further experimental and computational evidences for the concerted ANDN mechanism of aromatic nucleophilic substitution

Article abstract of DOI:10.1016/j.jfluchem.2014.04.012

Trimethylsilylphosphines PhRPSiMe₃ (1 R = Me, 2 R = Ph) have been shown to phosphinodefluorinate 1,2,3- (3), 1,3,5- (4) and 1,2,4-trifluorobenzene (5) in benzene solution or without solvent at 150-200 °C to form the respective (difluorophenyl)methylphenyl- and -diphenylphosphines in high NMR yields under harder conditions compared to the previously reported reactions of Me₂PSiMe₃ with the same substrates. Hexafluorobenzene (6), pentafluorobenzene (7) (at 150 °C), octafluorotoluene (8) and pentafluoropyridine (9) (at 20 °C) react with phosphine 2 without a solvent almost quantitatively under fluorine 1,4-disubstitution (for 6) or monosubstitution (for 7-9) by the Ph₂P group to give the corresponding (polyfluoroaryl)diphenylphosphines in 50-60% (for 6-8) and 95% (for 9) isolated yields. The regio and substrate selectivities exhibited by 3-5 in the reactions of the single substrates and in competitive reactions of 3 vs. 4 with 1 or 2 and 4 vs. 5 with 2 indicate relative fluorine substituent rate factors f_o-F > f_m-F consistent with the concerted A_ND_N mechanism which is supported by high level quantum chemical DFT-studies for the reactions of the substrates 3 and 4 with 1, 2 and 10 as well as for 6 with 2.

Full text of DOI:10.1016/j.jfluchem.2014.04.012

Accepted Manuscript
Title: Phosphinodefluorination of Polyfluorobenzenes by
Silylphosphines Ph(R)PSiMe3 (R = Me, Ph): Further
Experimental and Computational Evidences for the Concerted
ANDN Mechanism of Aromatic Nucleophilic Substitution
Author: S.I. Zhivetyeva L.I. Goryunov I.Yu. Bagryanskaya J.
¨
Grobe V.D. Shteingarts E.-U. Wurthwein
PII:
S0022-1139(14)00103-1
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.jfluchem.2014.04.012
FLUOR 8308
To appear in:
FLUOR
Received date:
Revised date:
Accepted date:
12-2-2014
17-4-2014
18-4-2014
Please cite this article as: S.I. Zhivetyeva, L.I. Goryunov, I.Yu. Bagryanskaya,
¨
J. Grobe, V.D. Shteingarts, E.-U. Wurthwein, Phosphinodefluorination of
Polyfluorobenzenes by Silylphosphines Ph(R)PSiMe3 (R = Me, Ph): Further
Experimental and Computational Evidences for the Concerted ANDN Mechanism
of Aromatic Nucleophilic Substitution, Journal of Fluorine Chemistry (2014),
http://dx.doi.org/10.1016/j.jfluchem.2014.04.012
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*Graphical Abstract - Pictogram
Page 1 of 31

*Graphical Abstract - Synopsis
PhRPSiMe3 (R = Me, Ph) phosphanodefluorinate trifluoro-, hexafluoro-, pentafluorobenzene,
octafluorotoluene, and pentafluoropyridine to give respective phenyl-fluorinated methyldiphenyl-
and –triiphenylphosphanes. The regio and substrate selectivities exhibited by trifluorobenzenes
and high level quantum chemical DFT-studies support the concerted ANDN mechanism.
1
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*Highlights (for review)
Highlights
PhRPSiMe3 (R = Me,Ph) phosphanodefluorinate polyfluorobenzenes or perfluoropyridine.
Phenyl-fluorinated methyldiphenyl- and –triiphenylphosphanes can be thus prepared.
The selectivities in this reactions are consistent with the ANDN mechanism.
The high level gas phase quantum chemical DFT-studies support this mechanism.
Page 3 of 31

*Manuscript
Phosphinodefluorination of Polyfluorobenzenes by Silylphosphines Ph(R)PSiMe3
(R = Me, Ph): Further Experimental and Computational Evidences for the
Concerted ANDN Mechanism of Aromatic Nucleophilic Substitution
S.I. Zhivetyeva,a,b L.I. Goryunov,a,† I.Yu. Bagryanskaya,a J. Grobe,c,*
V.D. Shteingarts,a,* E.-U. Würthweind,*
a
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division of RAS, Lavrentiev Ave. 9, 630090
Novosibirsk, Russian Federation
b
c
d
Novosibirsk State University, 630090 Novosibirsk, Pirogova Str., 2
Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstraβe 28/30, 48149 Münster, Germany
Organisch-Chemisches Institut, Universität Münster, Corrensstraβe 40, 48149 Münster, Germany
Keywords:
Phosphines
Polyfluoroarenes
Aromatic substitution
Nucleophilic substitution
Ab initio calculations
Trimethylsilylphosphines PhRPSiMe3 (1 R = Me, 2 R = Ph) have been shown to phosphinodefluorinate
1,2,3- (3), 1,3,5- (4) and 1,2,4-trifluorobenzene (5) in benzene solution or without solvent at 150–200 ºC
to form the respective (difluorophenyl)methylphenyl- and -diphenylphosphines in high NMR yields
under harder conditions compared to the previously reported reactions of Me2PSiMe3 with the same
substrates. Hexafluorobenzene (6), pentafluorobenzene (7) (at 150 ºC), octafluorotoluene (8) and
pentafluoropyridine (9) (at 20 ºC) react with phosphine 2 without a solvent almost quantitatively under
fluorine 1,4-disubstitution (for 6) or monosubstitution (for 7–9) by the Ph2P group to give the corresponding
(polyfluoroaryl)diphenylphosphines in 50–60% (for 6–8) and 95% (for 9) isolated yields. The regio and
substrate selectivities exhibited by 3–5 in the reactions of the single substrates and in competitive reactions
†
deceased
* Corresponding authors:
E-mail address: grobe@uni-muenster.de (J. Grobe);
Tel.: +7-383-330-9171; Fax.: +7-383-330-9752. E-mail address: shtein@nioch.nsc.ru (V.D. Shteingarts);
E-mail address: wurthwe@uni-muenster.de (E.-U. Würthwein).
1
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of 3 vs. 4 with 1 or 2 and 4 vs. 5 with 2 indicate relative fluorine substituent rate factors fo-F > fm-F
consistent with the concerted ANDN mechanism which is supported by high level quantum chemical DFT-
studies for the reactions of the substrates 3 and 4 with 1, 2 and 10 as well as for 6 with 2.
1. Introduction
Tertiary fluoroarylphosphines are of considerable interest as ligands of catalytically active
transition metal complexes [1] and starting materials for various phosphorus containing compounds,
for example benzoheterocycles [2] or 1,4-naphthoquinone phosphonium betaines [3]. One of the
widely used methods to prepare fluoroarylphosphines is the phosphinodefluorination of fluoroarenes
by secondary phosphines (PНR1R2 [4,5]), their alkaline salts (MPR1R2, M = Li, Na, K) [5–8] or
trimethylsilyl and -stannyl derivatives (R1R2РEMe3; R1, R2 = Me, iso-Pr, tert-Bu, Ph, CH2CH2PPh2; E =
Si, Sn) [4,9–13]. Thus, phosphines PНR1R2 were used as nucleophiles in reactions only with such
active substrates as pentafluoropyridine [4] and tetrafluorophthalonitrile [5]. The interaction of the
salts Me2PLi and Ph2PK, respectively, with bromo- [8] or iodofluorobenzenes [7] resulted in heavy
halogen substitution, whereas the reaction of C6F5Cl with Me2PLi led to chlorine and fluorine
substitution and thus to a complex mixture of products [8]. Tetrafluorophthalonitrile with the
phosphide Ph2PNa gave only intractable tars [5]. Dialkyl(trimethyl)silyl- and -stannylphosphines
R1R2РEMe3 (R1, R2 = Me, iso-Pr, tert-Bu; E = Si, Sn), which are of intermediate nucleophilicity between
the phosphines PНR1R2 and their salts MPR1R2, were found to be rather convenient, selective and efficient
reagents for fluorine substitution by dialkylphosphinyl groups R1R2P in polyfluoroarenes C6F5X (X = H, F,
Cl, CF3, etc.), 1,2,3- or 1,3,5-tri-, 1,2- or 1,3-difluorobenzenes and pentafluoropyridine giving the
corresponding (fluoroaryl)dialkylphosphines [4,9–13]. Since fluoroaryl phosphines are also of
considerable interest as ligands, the less nucleophilic phenyl- and diphenylphosphines Ph(R)РSiMe3 (R =
tert-Bu, Ph [4], CH2CH2PPh2 [11]) were used in phosphinodefluorination reactions only with
pentafluoropyridine, the most active among the above substrates [4]. Quite recently, functionalized
triaryl- and diarylalkylphosphines were reported to be easily accessible via fluoride catalyzed P–C
coupling of electron-withdrawing functionalized fluoroaromatics and silylated phosphines [14].
However, the dimethylphosphinodefluorinations of polyfluoroarenes with Me2PSiMe3 in benzene or
MeCN [9] and dimethylaminodeflorination of pentafluorobenzene with Me2NSiMe3 in MeCN [10]
were reported not to be affected by a CsF or Et4NF additive.
2
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Considering the synthetic importance of the above polyfluoroarene reactions with reagents
R1R2РEMe3, their mechanism is of interest. In our previous publication [12] for the reactions of 1,2-,
1,3-difluoro-, 1,2,3- and 1,3,5-trifluorobenzenes with the phosphines Me2РM (M = SiMe3, SnMe3 or Li)
the fo-F > fm-F correlation of fluorine substituent rate factors was found, the opposite one being expected
for the two-step SNAr mechanism with a Meisenheimer-intermediate-like transition state (TS). Based
on the results of quantum-chemical DFT and MP2 calculations, this finding was rationalized in terms
of the concerted ANDN mechanism proceeding via a single TS. Such a type of an aromatic nucleophilic
substitution mechanism was previously suggested for the transfer of a 1,3,5-triazinyl group between
different ligands and nucleophiles [15a–e] and for the replacement of a pentafluorophenoxy group by a
fluoride anion in 4-pentafluorophenoxy-2,3,5,6-tetrafluoropyridine [15f]. Computationally this
mechanism was found for the gas phase reactions of halobenzenes [16a–e] and halonitrobenzenes [16f]
with halide anions, as well for the nucleophilic defluorination of 2,3,4,5,6-pentafluorobiphenyl by
ammonia, microsolvated lithium fluoride or lithium hydroxide [17].
Pursuing the further development of the application of polyfluoroarene reactions with the
phosphines R1R2РEMe3 for synthesis of polyfluorophenylphosphines and the additional test of
relevance of the notion of the ANDN mechanism for these reactions, in this paper we present the results
obtained with the silylphenylphosphines МеPhРSiMe3 (1) and Ph2РSiMe3 (2) to introduce МеPhР and
Ph2P groups, respectively, into 1,2,3- (3), 1,3,5- (4) and 1,2,4-trifluorobenzene (5) and to reveal the
positional and substrate selectivities in these phosphinodefluorination reactions. Furthermore, the
results of diphenylphosphinodefluorination of hexafluorobenzene (6), pentafluorobenzene (7),
octafluorotoluene (8) and pentafluoropyridine (9) with phosphine 2 are reported. High level quantum
chemical DFT-studies were performed concerning the starting materials and the TSs of the
phosphinodefluorination reactions.
2. Results and Discussion
2.1. Reaction conditions and product distributions
As expected, weakening the reagent nucleophilicity in going from Me2PSiMe3 (10) [9,10,12] to
silylphosphines 1 and 2 requires somewhat harder conditions for phosphinodefluorination of
trifluorobenzenes 3–5 (Scheme 1). So, 3 and 1 (molar ratio 1.7:1.0) reacted in benzene at 150 °C (30 h)
(~40% conversion) and then at 175 °C (30 h) to form a 1.7:1.0:1.1 mixture of (2,3-
difluorophenyl)(methyl)phenylphosphine (11), (2,6-difluorophenyl)(methyl)phenylphosphine (12), and (3-
3
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fluoro-1,2-phenylene)bis[methyl(phenyl)phosphine] (13) in a total ~100% yield (according to 19F and
31P NMR control). According to the 19F and 31P NMR spectra, phosphine 13 forms a 1.4:1.0 mixture of
two diastereomers. Since the phosphines 11–13 are difficult to be individualized owing to oxidation by
atmospheric oxygen, for identification their mixture was transformed by treatment with sulfur into a
3.3:2.3:1.2:1.0 mixture of the corresponding phosphinethiones 14, 15 and diastereomeric bis-
phosphinethiones 16 (RR,SS) and 16 (RS,SR) (Scheme 1), which were isolated in 37%, 30%, 10% and 8%
yields, respectively. The X-ray structures of 16 (RR,SS) and 16 (RS,SR) are depicted in Figure 1.
Scheme 1. Reactions of trifluorobenzenes with МеPhРSiMe3 (1).
16(SS)
16(RS)
4
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Figure 1. Perspective views of molecular structures of 16(SS) and 16(RS) in their crystals (30%
thermal ellipsoid). The F1 atom of these compounds is disordered over the two positions with
F1/H17 : F1’/H14 occupancy ratio of 0.85 : 0.15(1) for 16(RS) and 0.84 : 0.16(1) for 16(SS).
In
a
similar reaction, the substrate
4
(4:1 = 1.7:1) was transformed to (3,5-
difluorophenyl)(methyl)phenylphosphine (17) by consecutive heating at 175 °C (16 h) (~30% conversion)
and 200 °С (50 h) (~100% conversion, 70% isolated yield). Reaction of 5 with 1 (1.6:1) without solvent
showed intermediate activity to give ~100% conversion to (2,5-difluorophenyl)(methyl)phenylphosphine
(18) at 200°C within 11 h (72% isolated yield).
The diphenylphosphinodefluorination of 3–5 by phosphine 2 in benzene occurs with appreciable
rates only above 170 °С (Scheme 2). Compound 3 reacts with 2 in benzene at 180°C to give quantitatively a
2.7:1 mixture of (2,3-difluorophenyl)diphenylphosphine (19) and (2,6-difluorophenyl)diphenylphosphine (20)
(36% and 6% isolated yields, respectively). The less reactive compounds 4 and 5 reacted with phosphine 2
in benzene at 200 °C to undergo a ~100% conversion to (3,5-difluorophenyl)diphenylphosphine (21) (70%
isolated yield) and (2,5-difluorophenyl)diphenylphosphine (22) (72% isolated yield), respectively.
Scheme 2. Reactions of trifluorobenzenes with Ph2РSiMe3 (2).
The (difluorophenyl)diphenylphosphines obtained are partly oxidised by atmospheric oxygen
during the isolation process, thus reducing their yields. Thus, upon isolation of 21 by TLC, (3,5-
difluorophenyl)diphenylphosphineoxide (23) was also obtained (7% isolated yield). Phosphines 19 and
22 were oxidized by H2O2 to (2,3-difluorophenyl)diphenylphosphineoxide (24) and (2,5-
difluorophenyl)diphenylphosphineoxide (25), respectively.
5
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Thus, the reactions described above demonstrate, that the silylphosphines 1 and 2, despite being
less active phosphinodefluorinating agents towards polyfluoroarenes than their analogue 10 [9,10,12], can
be used to prepare the corresponding polyfluorophenylphosphines and, further, their oxides and
sulfides.
On going from 3–5 to 6 and 7, due to of the increasing the number of fluorine substituents, and,
especially, to 8 and 9, owing to embedding the unit CCF3 or N into the ring, the polyfluoroarene
activity towards phosphinodefluorination reagents is enhanced. Polyfluoroarenes 6–9 react with
phosphine 2 without solvent almost quantitatively with fluorine substitution by the Ph2P group (according to 19F
31
and P NMR spectra) to give the corresponding polyfluoroaryldiphenylphosphines in 50–60 % (for 6–8)
and 95 % (for 9) isolated yields, respectively (Scheme 3). For compounds 6 and 7 this occurs at rather high
temperature (150 ºC). Thus, 6 gives the disubstituted product 1,4-bis-(diphenylphosphino)tetrafluorobenzene
(26) (59% isolated yield) which undergoes a partial oxidation upon isolation by TLC (NMR data). This
result is in accord with that obtained earlier by reacting C6F6 with Me2РSiMe3 [9] and shows that the secondary
para-phosphinodefluorination occurs, at least, not slower than the first one, apparently due to the first removal
of an electron donating fluorine substituent and the combined effect of five successively standing fluorine
atoms with the middle one as the most mobile (cf. [18]). In accord with this, 7 reacts exclusively with
formation of the monosubstituted product: diphenyl(2,3,5,6-tetrafluorophenyl)phosphine (27) (60% isolated
yield). The diphenylphosphinodefluorinations of 8 and 9 by 2 differ sharply from those of 6 and 7, due to
the strong activating influence of the ring members N or CCF3. The reactions proceed already at room
temperature to yield diphenyl[2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenyl]phosphine (28) (53% isolated
yield) and 4-(diphenylphosphinyl)-2,3,5,6-tetrafluoropyridine (29) (95% isolated yield), respectively. As
expected, 9, judging from the transformation time (Scheme 3), is much more active than 8. Phosphine
29 was previously obtained from the analogous reaction in benzene at 50 °C in the 81% yield [4].
Scheme 3. Reactions of polyfluoroarenes with Ph2РSiMe3 (2).
6
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3. Discussion of the Reaction Mechanism
3.1. Substrate and Positional Selectivities
In analogy to reactions of di- and trifluorobenzenes with10 [9,12,13], the phosphinodefluorination of
trifluorobenzenes by silylphosphines 1 and 2 could be supposed to proceed via the concerted mechanism.
In general (except the regioselectivity exhibited by 3 in its reaction with 2), this assumption turned out
consistent with the observed fo-F > fm-F correlation, which is opposite to the fm-F > fo-F one, conventionally
considered as typical for the two-step SNAr mechanism with a Meisenheimer-intermediate-like (“late”)
TS [18,19]. The above reaction conditions and transformation rates/degrees show on a first glance a
smaller activity of 4, containing mutual meta-located fluorine atoms, compared with its isomers 3 and
5, but direct experiments were obviously needed for a firm conclusion. Hence, to get a more distinct
pattern of the trifluorobenzenes substrate regioselectivity in the reactions under study, competitive
reactions of compounds 3 and 4 with phosphines 1 and 2 (Scheme 4), and compounds 4 and 5 with
phosphine 2 (Scheme 5) were studied by NMR measurements in sealed tubes.
In both cases the product distributions clearly display the higher activity of trifluorobenzenes 3 and 5
in comparison with their isomer 4. This does not correspond to the above correlation expected for the SNAr
mechanism and exhibited by 4 with Me2NSiMe3, but is in line with the substrate selectivities found for
the inferred ANDN reactions of the same substrates with 10 [12]. The substrate/regioselectivities observed
for 3 and 5 depend on the silylphosphine used. Thus, for the reaction of reagent 1 at 125 °C the product
distribution is markedly in favor of phosphines 11 and 12 over 17 and of the 2-position over the 1-one
in 11, but lowers in going to 150 °C. In the competitive reaction with phosphine 2 the substrate
selectivity is also in favor of 3, but, in contrast to the reaction of phosphine 1, increases with temperature
(from 150 to 180 ºC).
To discuss the revealed selectivities in terms of substituent electronic effects, one should make sure that
corresponding competitions are enthalpically controlled. Provided that the linear dependences ln (ki/kj)
= f (1/T) are valid (ki/kj – the ratios of the competitive reactions rate constants as provided by the
corresponding product distributions), the isokinetic temperatures (Tiso) found from the temperature
dependences of product distributions indicate that this condition is fulfilled for the regioselectivity of 3 in
the reactions with 1 at 125–150 °C (Tiso ~ 420 K), with 2 at 150–180 °C (Tiso ~518 K; Scheme 4), and also for
the 3 vs 4 competition in the reaction with 1 at 125–150 °C (Tiso = 445 K; Scheme 5). On the contrary,
the 3 vs 4 competition in the reaction with 2 at 150–180 °C (Tiso ~217 K; Scheme 4) is entropically
controlled.
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Scheme 4. Competitive reactions of trifluorobenzenes 3 and 4 with RPhPSiMe3 (R = Me, Ph).
Scheme 5. Competitive reaction of trifluorobenzenes 4 and 5 with Ph2PSiMe3.
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Scheme 6. Regioselectivity of trifluorobenzene 3 with RPhPSiMe3 (R = Me, Ph).
Following this, the enthalpically controlled correlation fo-F > fm-F observed in the substrate
selectivities and in the regioselectivity of 3 with 1 excludes the fm-F >fo-F correlation expected for the SNAr
mechanism [18,19], but can be explained in terms of the ANDN mechanism as caused by the
predominance of inductive effects in the combined substituent influence on the reaction rates. This is in line
with the quantum-chemically predicted nature of the TS depicted in Figure 2 and characterized by
conservation of the substantial ring aromaticity. The increasing stability (reducing ΔH≠) in the sequence
TS-1 < TS-2 < TS-3 is obviously determined by the –I-effect correlation ortho-F > meta-F. Besides, according
to our calculations in ref. [12], 1,2,3-trifluorobenzene is destabilized compared to 1,3,5-trifluorobenzene
by 32.2 kJ/mol, obviously due to the repulsion of the neighboring dipoles Сδ+–Fδ–. So, the observed
sequence of ΔH≠ values in the above TS series is partly due to an appreciable reduction of this dipole
interaction by transformation of substrate 3 to TS-2 and, even more, to TS-3.
Figure 2. TS structures for the reactions of compounds 4 (TS-1), 3 (position 1, TS-2) and 3 (position 2,
TS-3) withRPhPSiMe3 (R = Me, Ph).
9
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Unlike the reaction of 3 with 1, the regioselectivity of 3 in its reaction with the less active
nucleophile phosphine 2 (Schemes 4 and 6) indicates the activating correlation ortho-F < meta-F, which
is similar to that allegedly peculiar to SNAr reactions [19] but is really not possible to be unambiguously
rationalized at the moment (vide infra).
The competitive reactions of the trifluorobenzenes 3 and 4, respectively, with the even weaker
nucleophile methyl(phenyl)phosphine occurred at much higher temperature (225 °C) and show a
similar substrate selectivities (Scheme 7) compared to the above reaction with 2. However, the
regioselectivity displayed by 3 is different and can not be excluded to be entropically controlled.
Scheme 7. Competitive reaction of trifluorobenzenes 3 and 4 with PhMePH.
On the other side, it seemed reasonable to compare the (R)PhPSiMe3 regioselectivities in the
above reactions with that displayed by a significantly stronger nucleophile. For this purpose, Ph2PLi
was chosen to react with 5 which exhibits a pronouncedly high regioselectivity with phosphine 2 (vide
supra). Unlike this, the reaction with Ph2PLi led to a mixture of three monophosphinodefluorination products:
22, 19 and (3,4-difluorophenyl)diphenylphosphine (30) in only ~35% total yield and in á 4.7:1.0:1.0 ratio
(NMR data); the reaction was accompanied by the additional formation of not identified phosphorus
containing by-products. Upon TLC separation of the mixture, the above phosphines were partially
oxidized, so that mixtures were isolated of phosphines 19 and 30 with oxide 24 and (3,4-
difluorophenyl)diphenylphosphineoxide (31), respectively. The mixture of 19 and 24 was turned to oxide
24 by simple stirring its acetone solution without protection against air. The fraction consisting of
phosphine 30 and its oxide 31 was oxidized by H2O2 to yield 31 which, unfortunately, could not be
obtained as an analytically pure specimen because of the small amount available. However, the NMR
spectral data of 30 and 31 and HRMS analysis of 31 (Experimental section) clearly prove the structures.
One may see that the formation of 22 as the principal monophosphanodefluorination product
corresponds to the regioselectivity displayed by the same educt with reagent 2, which is, at least in part,
10
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probably formed via the direct substitution. However, the formation of phosphine 19 clearly reveals the
aryne mechanism involvement which, in principle, may account for all the above products (Scheme 8).
Scheme 8. Reaction of trifluorobenzene 5 with Ph2PLi.
3.2. Quantum chemical DFT calculations
In principle, the fo-F > fm-F correlation does not allow to discriminate between the two-step SNAr
mechanism with the substrate-like (“early”) TS and the ANDN mechanism with the substrate-like TS in
which a benzenoid aromaticity of the ring is substantially conserved. Chambers et al. explain the fortho
>
fmeta correlation in terms of the “early” SNAr TS a priori assuming the SNAr mechanism, not
considering the ANDN mechanism [19b]. However, the “early” SNAr TS is normally associated with the
high reactivity of the substrate and/or of the reagent which is not the case in the reactions under this
study. On the other hand, the fo-F < fm-F substrate/regioselectivity is not an unambiguous evidence for the
SNAr mechanism because such a selectivity can be realized within the ANDN mechanism since the TS
may be substantially close to the Meisenheimer-adduct-like limit [20]. Therefore, to resolve this
dichotomy in our previous paper [12] we combined the fortho > fmeta correlation, experimentally found for
the fluorobenzenes phosphinodefluorination by Me2PSiMe3, with the results of quantum chemical DFT-
calculation which clearly revealed the absence of a Meisenheimer intermediate (cf. [17]).
Following this methodology, in this study high level quantum chemical DFT-calculations were
performed concerning the starting fluorobenzenes 3, 4 and 6 and the phosphines 1, 2 and 10 with
special regard to the respective TSs of their phosphinodefluorination reactions. For the geometry
optimizations and energy determinations the method M06-2X/6-311+G(d,p) [21] was used as
11
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implemented in the GAUSSIAN 09 series of programs [22]. In order to simulate the influence of
benzene, which often was used as solvent in this study, the self consistent reaction field method using
the CPCM polarizable conductor model with benzene as solvent was employed. Furthermore, the
dispersion method D3 as recently developed by Grimme was used for the optimizations in order to
correct for intramolecular interactions [23].
Importantly, TS structures corresponding to a ANDN mechanism have been obtained for all the
above substrates. All TSs are characterized by a staggered conformation with respect to the forming
C..P-bond with the TMS-group in gauche position. The Si..F-distances (3.5 – 4.0 Å) are long and give
no indication for a significant silicon-fluorine interaction.
Table 1 summarizes the calculated energies of activation E‡ at 0 K (including zero point
correction) as well as the free Gibbs energies of activation G‡ for 298 K and for 448 K, which were
obtained from the respective differences of the sum of the starting materials and the data of the TSs
resulting from the nucleophilic attack of the phosphine at the respective fluorinated carbon atom of the
aromatic moiety. The large calculated differences between the E‡ and the G‡ values indicate the
importance of the activation entropy in these reactions characterized by a highly ordered TS. The
activation energies for the reaction of 1,3,5-trifluorobenzene 4 are calculated to be the highest within this
series of reactions, while those for the 1-position of 1,2,3-trifluorobenzene 3 are slightly smaller,
indicating higher reactivity at high temperatures, thus reflecting the substituent effect of the second fluorine
atom in 2-position. Attack at the central position (position 2) of 3 is according to the calculations even
more facile, indicating the substituent effect of both neighboring fluorine atoms. Within the series of
nucleophiles 1, 2 and 10, as expected, lowest barriers were calculated for the latter. In accordance with
the experimental data, this nucleophile reacts at lower temperatures compared to the phenyl derivatives.
In most of the examples phosphine 1 is calculated to have a slightly lower barrier of activation
compared to phosphine 2, again in good agreement with the experimental data. We also included the
reaction of hexafluorobenzene 6 with phosphine 2 in this study. Not unexpectedly, the reaction of this
very electron-poor benzene derivative with this particular phosphine is calculated to have the lowest
barrier within this series of fluorinated arenes.
In Table 1, the characteristic C–P and C–F distances of the TSs at the M062x-level (including
GD3-correction and the CPCM-model for benzene) are also included. The C–P distances vary in the
range of 2.00 – 2.11 Å, the C–F distances from 1.42 – 1.50 Å. For comparison, the reacting fluorinated
benzenes 3, 4, and 6 show calculated C–F bond lengths of 1.32 – 1.34 Å, whereas the final products are
characterized by C–P bond lengths of ca. 1.85 – 1.87 Å. It is difficult to correlate these distances with the
12
Page 15 of 31

Table 1: Calculated TS properties: C–P and C–F distances [Å], activation energies ΔE‡ [0 K, kJ/mol],
and Free Gibbs Energies ΔG‡ (298 and 448 K) for the reactions of 3, 4 and 6 with
trimethylsilylphosphanes 1, 2 and 10 using the CPCM-method for benzene as solvent (M06-2X/6-
311+G(d,p)//M06-2X/6-311+G(d,p)+GD3+CPCM (solvent = benzene)).
TS C–P
TS C–F
ΔE‡
(0 K)
[kJ/mol]
ΔG‡
(298K)
[kJ/mol]
ΔG‡
(448K)
[kJ/mol]
Reaction
components
[Å]
[Å]
3 (position 1) + 10
3 (position 1) + 1
3 (position 1) + 2
2.0971
2.0428
2.0563
1.4383
1.4662
1.4657
79,21
84.12
88.98
135,21
141.92
146.83
163,32
170.31
175.41
3 (position 2) + 10
3 (position 2) + 1
3 (position 2) + 2
2.0942
2.0659
2.0035
1.4439
1.4658
1.4968
76.72
80.87
89.45
132.13
142.88
150.91
159.84
173.68
184.48
4 + 10
4 + 1
4 + 2
2.1173
2.0788
2.0707
1.4236
1.4371
1.4458
84.79
92.40
95.76
135.57
147.98
150.37
160.55
175.71
177.03
6 + 2
2.0593
1.4531
68.97
125.53
153.74
Figure 3. Quantum chemically calculated free Gibbs energy profile (448 K) for the reaction of 4 with
methylphenyltrimethylsilylphosphine. Relative energies [kJ/mol](M06-2X/6-311+G(d,p)//M06-2X/6-
311+G(d,p) + GD3+ CPCM; solvent = benzene)
13
Page 16 of 31

activation barriers of the respective systems and analyze them in terms of the TS character. The potential
energy surface around the TSs seems to be rather soft, obviously because of the flexibility of the C–P
bond, thus allowing variable structural properties. However, some interesting trends can be discerned.
For example, the TS C–F distances tend to lengthen from 10 through 1 to 2, as expected for the TSs to
become “later” with the phosphine reagent deactivation. Simultaneously, the TS C–P distances
lengthen and C–F distances shorten in going from 3 and 4 to 6 which is in line with the TSs to become
“earlier” with the polyfluoroarene substrate activation. It should be mentioned, that in all cases this first
TS is rate determining. However, these TSs do not lead directly to the free products phosphinylbenzene
and trimethylfluorosilane. In one case (reaction of 4 with 1) we studied the reaction profile in more
detail (Figure 3). We obtained a shallow minimum for a first substitution product, featuring a five-
coordinate phosphorus atom with the fluorine atom attached to it (P-F distance: 1.8841 Å). A very
small second barrier has to be surmounted in order to complete the quite exothermic reaction by
elimination of Me3SiF and the formation of the arylphosphine.
Experimentally, the positional selectivity of 3 in its reaction with phosphine 2 (Schemes 4 and 6)
indicates the activating correlation ortho-F < meta-F (vide supra). As it was argued above, within the
ANDN mechanism it could be a manifestation of the substantially more Meisenheimer-adduct-like TS in
contrast to the reactions of 3 with the stronger nucleophiles Me(R)PSiMe3 (R = Me [12], Ph). However,
this suggestion is not confirmed by the calculated energy correlation of the respective TSs (Table 1).
Probably, a steric consequence of the reagent solvation can not be excluded in this case.
4. Conclusion
In conclusion, the results presented in this article about reactions of polyfluorobenzenes with
silylphosphines (Ме)PhPSiMe3 (1) and Ph2PSiMe3 (2) essentially contribute to a knowledge both about
the preparation and the formation mechanism of poly- and oligofluoroarylphosphines. 1 and 2 have
been found capable to phosphinodefluorinate 1,2,3- (3), 1,3,5- (4) and 1,2,4-trifluorobenzene (5) at 170–
240 ºC to give the respective (difluorophenyl)methylphenyl- and -diphenylphosphines in reasonable to good
yields. Isomeric phospanes 11 and 12 and diphosphine 13 formed by 3 with 1 were characterized as
phosphinethiones 14, 15 and diastereomeric bis-phosphinethiones 16 (RR,SS) and 16 (RS,SR), the
latter diastereomers having been isolated and characterized by the X-ray analysis.
(Difluorophenyl)diphenylphosphines 19, 21, and 22 were oxidized to the respective oxides. In going
to hexa- (6), pentafluorobenzene (7) and, especially, to perfluorotoluene (8) and -pyridine (9) the
reactivity of fluoroarene substrates markedly increased to undergo diphenylphosphinodefluorination with 2
14
Page 17 of 31

at 150 °C for 6 and 7 or 20 °C for 8 and 9. Competitive reactions of trifluorobenzenes 3 and 4 with
phosphines 1 and 2 or 4 and 5 with 2 clearly displayed the higher activity of 3 and 5 in comparison
with their isomer 4. These substrate selectivities are not expected for the SNAr mechanism, but
consistent with those reported by us previously for the (putatively) ANDN reactions of the same
substrates with Me2PSiMe3. High level quantum chemical DFT-studies, performed for the starting
materials 3, 4 and 6 and the TSs of their phosphinodefluorination reactions, have corroborated a
validity of the notion of the ANDN mechanism. The correlations of the calculated activation energies are
generally in accord with the experimental substrate/positional selectivities, besides the positional
selectivity displayed by 1,2,3-trifluorobenzene 3 in its reaction with phosphines 1, 2 and 10.
5. Experimental
The NMR spectra were recorded with a Bruker AV 300 (1H: 300.13 MHz, 13C: 75.47 MHz, 19F:
31
282.36 MHz, P{1H}: 121.49 MHz) spectrometer in the respective deuterated solvents relative to the
residual proton chemical shifts of acetone (δH 2.07 ppm), chloroform (δH 7.25 ppm, δC 77.00 ppm),
C6H6 (δC 128.00 ppm) in 1H NMR spectra, Me4Si in 13C NMR spectra, external C6F6 (δF = –163.0 ppm)
19
in F NMR spectra, and H3PO4 in 31P spectra. High-resolution mass spectra (HRMS) were measured
with a DFS Thermo scientific instrument (EI, 70 eV). The melting points were determined on an FP
900 Thermosystem microscope melting point apparatus (Mettler-Toledo International Inc., Zürich,
Switzerland). The XRD data were collected with a Bruker Kappa Apex II CCD diffractometer using φ,
ω scans of narrow (0.5°) frames with Mo Kα radiation (λ = 0.71073 Å) with graphite monochromator
at T = 200 (2) K. The structures were solved by direct methods and refined by full-matrix least-squares
method against all F2 in anisotropic approximation (isotropic for H atoms in compound LS19) using
the SHELX-97 programs set [24]. The H atoms positions were calculated with the riding model.
Absorption corrections were applied empirically using SADABS programs [25]. The bond lengths and
bond angles are the same as the statistical means [26]. The obtained crystal structures were analyzed for
short contacts between non-bonded atoms using the PLATON program [27]. Tables listing detailed
crystallographic data, atomic positional parameters, and bond lengths and angles are available as
CCDC 952601, 952602 from the Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Solvents were distilled. Pentafluorobenzene, octafluorotoluene, pentafluoropyridine, C6H6, C6D6
were purified by vacuum distillation (0.09 kPa) and dried by molecular sieves 3 Å.
15
Page 18 of 31

Polyfluorobenzenes 3–6 (98–99%) were purified by vacuum distillation (0.09 kPa) and dried by
calcium hydride. Compound 1 was prepared according to [28] and compound 2 according to [29].
5.1. Reaction between (3) and (1)
Compounds 1 (0.167 g, 0.851 mmol), 3 (0.168 g, 1.272 mmol), and C6D6 (0.30 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.09 kPa), allowed to warm to ambient temperature and kept at 150 °C for 30 h and then 175
°C for 30 h while NMR spectra were periodically recorded. The resulting solution was analysed by
NMR spectroscopy (Scheme 1):
19
3
3
4
Phosphine 11: F NMR (C6D6): δ = –131.4 [ddd, 1F, JFP = 36.7 Hz, JFF = 22.1 Hz, JFH ≈ 6
Hz, F2], –138.9 [ddm, 1F, 3JFF = 22.1 Hz, 3JFH = 10.0, F3] ppm. 31P{1H} NMR (C6D6): δ = –35.8 [dd,
1P, 3JPF = 36.7 Hz, 4JPF = 2.5 Hz] ppm.
Phosphine 12: 19F NMR (C6D6): δ = –100.4 [ddd, 2F, 3JFP = 37.5 Hz, 4JFF and 3JFH ≈ 7 Hz, F2,6]
ppm. 31P{1H} NMR (C6D6): δ = –43.9 [t, 1P, 3JPF = 37.5 Hz] ppm.
Phosphine 13 (a mixture of two diastereomers): 19F NMR (C6D6): δ = –99.5 (m, 1F) and –99.7 (m,
1F) ppm. 31P{1H} NMR (C6D6): δ = –29.8 [dd, 1P, 3JPP = 112.3 Hz, 4JPF = 6.0 Hz, P1], –40.2 [dd, 1P,
3JPP = 112.3 Hz, 3JPF = 14.4 Hz, P2] and –31.1 [dd, 1P, 3JPP = 112.3 Hz, 4JPF = 6.0 Hz, P1], –38.9 [dd,
1P, 3JPP = 112.3 Hz, 3JPF = 14.4 Hz, P2] ppm.
5.2. (2,3-Difluorophenyl)(methyl)phenyl-λ5-phosphinethione (14), (2,6-difluorophenyl)(methyl)phenyl-
λ5-phosphinethione (15),
(R,S)-{2-fluoro-6-[(R,S)-methyl(phenyl)sulfanylidene-λ5-
phosphinyl]phenyl}(methyl)phenyl-λ5-phosphinethione [16(RR,SS)] and (R,S)-{2-fluoro-6-[(S,R)-
methyl(phenyl)sulfanylidene-λ5-phosphinyl]phenyl}(methyl)phenyl-λ5-phosphinethione [16(RS,SR)]
The volatile components of mixture obtained by the reaction between 3 and 1 were distilled off in vacuo
(0.09 kPa). The residue, S8 (0.036 g, 1.125 mmol) and C6H6 (2.0 mL) were kept at 90–95 °C under argon
for 8 h. After cooling to room temperature, traces of substrate were distilled off in vacuo (0.09 kPa), the
residue was separated by TLC (Sorbfil, chloroform–hexane, 1:1) to yield:
1
Phosphinethione 14 (RF = 0.5, 0.085 g, 37%), colorless liquid. H NMR (CDCl3): δ = 7.89
[ddddd, 1H, J = 13.4, 7.8, 6.2, 2 J ≈ 1.5 Hz, CArH], 7.80 [dd, 2H, J = 14.0, 7.3 Hz, C6H5], 7.41–7.52 (m,
3H, CArH), 7.33 [dddd, 1H, J = 2  ~8.7, 8.0, 1.7 Hz, CArH], 7.20–7.27 (m, 1H, CArH), 2.4 [dd, 3H, 2JHP
16
Page 19 of 31

= 13.9 Hz, 5JHF = 1.9 Hz, CH3] ppm. 13C NMR (CDCl3): δ = 150.3 [ddd, 1JCF = 250.8, 2JCF = 13.5, 3JCP
2
= 1.5 Hz, C3], 150.2 [ddd, 1JCF = 252.1, JCF = 14.3, 2JCP = 8.9 Hz, C2], 133.3 [d, 1JCP = 86.0 Hz, C1’],
131.7 [d, 4JCP = 3.0 Hz, C4’], 130.1 [dd, JCP = 11.3, 1.3 Hz, C3’ or C2’], 129.6 [ddd, J = 8.3, ~3.4, ~1.5
3
4
Hz, C5], 128.7 [d, JCP = 12.9 Hz, C2’ or C3’], 124.7 [ddd, 2JCF = 13.7 Hz, JCF = 6.1 Hz, JCP = 4.6 Hz,
C4], 123.2 [dd, 1JCP = 74.5, 2JCF = 14.8 Hz, C1], 121.4 [dm, 2JCP = 17.3 Hz, C6], 21.2 [dd, 1JCP = 61.4, J
19
3
= 4.6 Hz, CH3] ppm. F NMR (CDCl3, C6F6 internal): δ = –129.6 [br.d, 1F, JFF = 22.4 Hz, F3], –138.7
3
4
5
31
[ddddd, 1F, JFF = 22.4 Hz, 3JFP = 9.5 Hz, 4JFH ≈ 6.2 Hz, JFH ≈ 4.5Hz, JFH ≈ 1.2 Hz, F2] ppm. P{1H}
NMR (CDCl3): δ = 33.2 [dd, 1P, 3JPF = 6.1 Hz, 4JPF = 3.0 Hz] ppm. HRMS: calcd. for С13H11F2PS [M]
268.0282; found 268.0279; Anal. calcd. for С13H11F2PS: C, 58.20; H, 4.13; found: C, 58.16; H, 4.46.
Phosphinethione 15 (RF = 0.4, 0.069 g, 30%), colorless liquid. 1H NMR (CDCl3): δ = 7.90 [ddm,
2H, 3JHF = 14.6 Hz, 3JHH ≈ 6.7 Hz, H3,5], 7.38–7.55 (m, 4H, CArH), 6.88 [ddd, 2H, 3JHP, 3JHH ≈ 8.5 Hz, 4JHH = 3.6
Hz, H2’,6’], 2.34 [dt, 3H, 2JHP = 14.1 Hz, 5JHF = 3.2 Hz, CH3] ppm. 13C NMR (CDCl3): δ = 162.6 [dd, 1JCF =
253.8 Hz, 2JCP = 7.9 Hz, C2,6], 134.1 [t, J = 11.1 Hz, C4], 133.5 [d, 1JCP = 86.8 Hz, C1’], 131.6 [d, 4JCP
=
3
2
2
3.0 Hz, C4’], 130.2 [d, JCP = 11.7 Hz, C3’,5’], 128.7 [dm, JCF ≈ 12.9 Hz, C3,5], 128.4 [d, JCP = 13.1
Hz, C2’,6’], 112.6 [dm, 1JCP ≈ 23.4 Hz, C1], 25.4 [dt, 1JCP = 61.4 Hz, 4JСF = 5.3 Hz, CH3] ppm. 19F NMR
31
3
(CDCl3, C6F6 internal): δ = –101.2 (m, 2F, F 2,6) ppm. P{1H} (CDCl3): δ = 29.1 [br. t, 1P, JPF ≈ 1.6
Hz] ppm. HRMS: calcd. for С13H11F2PS [M] 268.0282; found 268.0277; Anal. calcd. for С13H11F2PS:
C, 58.20; H, 4.13; found: C, 58.38; H, 4.23.
Phosphinethione 16(RR,SS) (RF = 0.1, 0.034 g, 10%), colorless liquid. Crystals suitable for X-
1
ray analysis were grown from hexane/benzene (1:10), m.p. 169–171 °C. H NMR (CDCl3): δ = 7.81
3
3
[dddd, 2H, JHP = 13.6 Hz, 3JHH ≈ 6.8 Hz, J = 1.0–1.5 Hz, H2’,6’ or H2’’,6’’], 7.71 [dddd, 2H, JHP = 14.2
Hz, 3JHH ≈ 6.9 Hz, J = 1.0–1.5 Hz, H2’’,6’’ or H2’,6’], 7.53 [dddd, 1H, 3JHH ≈ 7.7 Hz, 4JHF = 3.2 Hz, 5JHP = 1.2
Hz, H4], 7.36–7.51 (m, 7H, CArH), 7.10 [ddddd, 1H, 3JHF = 10.0 Hz, 3JHH = 7.7 Hz, 4JHH = 3.7 Hz, 2JHP
=
2
2
5
1.0–1.5 Hz, H3], 2.6 [d, 3H, JHP = 12.8 Hz, CH3], 2.5 [dd, 3H, JHP = 13.4 Hz, JHF = 2.7 Hz, CH3]
ppm. 13C NMR (CDCl3): δ = 164.1 [ddd, 1JCF = 254.8 Hz, 2JCP = 15.3 Hz, J = 1.1 Hz, C2], 140.4 [dd,
1JCP = 76.4 Hz, J = 5.5 Hz, C1], 136.8 [dd, 1JCP = 85.3 Hz, 3JCF = 3.5 Hz, C6], 135.7 [d, 1JCP = 84.0 Hz,
3
3
4
4
C1’’], 132.6 [ddd, JCF = 14.4 Hz, JCP = 10.3 Hz, JCP = 2.1 Hz, C4], 131.6 [d, JCP = 3.0 Hz, C4’ or
C4’’], 131.3 [ddd, 2JCP = 12.1 Hz, 3JCP = 9.2 Hz, 4JCF = 2.8 Hz, C5], 131.0 [d, 4JCP = 3.1 Hz, C4’’ or C4’],
130.9 [d, 3JCP = 10.6 Hz, C3’’,5’’], 129.4 [dd, 3JCP = 11.2 Hz, 5JCF = 2.4 Hz, C3’,5’], 128.7 [d, 2JCP = 12.6
Hz, C2’,6’ or C2’’,6’’], 128.4 [d, 2JCP = 13.0 Hz, C2’’,6’’ or C2’,6’], 126.7 [ddd, 1JCP = 72.3 Hz, 2JCP = 13.8, 3JCP =
11.0 Hz, C1’], 120.1 [ddd, 2JCF = 26.9 Hz, 3JCP = 4.3, 4JCP = 2.5 Hz, C3], 29.7 [dd, 3H, 1JCP = 59.0 Hz, 4JСF
= 4.2 Hz, CH3], 27.1 [d, 3H, 1JCP = 59.8 Hz, CH3] ppm. 19F NMR (CDCl3, C6F6 internal): δ = –89.7 (m, 1F)
ppm. 31P{1H} NMR (CDCl3): δ = 42.8 [dd, 1P, 3JPP = 7.9 Hz, 4JPF ≈ 7.6 Hz, P6], 35.0 [dd, 1P, 3JPF = 13.2 Hz,
17
Page 20 of 31

3JPP = 7.9 Hz, P1] ppm. HRMS: calcd. for С20H19FP2S2 [M] 404.0382; found 404.0375; Anal. calcd. for
С20H19FP2S2: C, 59.39; H, 4.74; F, 4.70; found: C, 58.99; H, 4.65; F, 4.32. The X-ray molecular
structure is depicted in Fig. 1.
Phosphinethione 16(RS,SR) (RF = 0.2, 0.028 g, 8%), colorless crystals. Crystals suitable for X-
ray analysis were grown from hexane/benzene (1:10), m.p. 173–176 °C. 1H NMR (CDCl3): δ = 7.79–
3
3
4
7.94 (m, 5H, CArH), 7.39–7.60 (m, 7H, CArH), 7.19 [ddd, 1H, JHF = 11.2 Hz, JHH = 8.3 Hz, JHH
13
= 3.6 Hz, H3], 2.3 [d, 3H, 2JHP = 13.0 Hz, CH3], 2.2 [dd, 3H, 2JHP = 13.9 Hz, 5JHF = 3.8 Hz, CH3] ppm. C
1
2
1
NMR (CDCl3): δ = 164.6 [dd, JCF = 255.0 Hz, JCP = 15.1 Hz, C2], 138.8 [dd, JCP = 76.6 Hz, J = 5.3
Hz, C1], 135.9 [d, 1JCP = 84.8 Hz, C6 or C1’’], 134.9 [d, 1JCP = 82.2 Hz, C1’’or C6], 132.9 [dd, 3JCF = 14.4
3
4
Hz, JCP = 9.6 Hz, C4], 131.9 [dd, JCP = 2.5 Hz, C4’ or C4’’], 131.5 [dd, 4JCP = 2.5 Hz, C4’’ or C4’], 130.6
[ddd, 2JCP = 13.8 Hz, 3JCP = 8.8 Hz, 4JCF ≈ 2.5 Hz, C5], 130.4 [d, 3JCP = 11.1 Hz, C3’’,5’’], 129.8 [d, 3JCP = 11.4
Hz, C3’,5’], 129.1 [d, 3JCP = 12.7 Hz, C2’,6’ or C2’’,6’’], 128.6 [d, 2JCP = 13.0 Hz, C2’’,6’’ or C2’,6’], 126.6 [ddd,
1JCP = 71.3 Hz, 2JCP = 13.0, 3JCP = 11.0 Hz, C1’], 120.6 [br. d, 2JCF = 27.6 Hz, C3], 29.8 [dd, 3H, 1JCP
=
58.5 Hz, 4JСF = 5.5 Hz, CH3], 28.3 [d, 3H, 1JCP = 61.2 Hz, CH3] ppm. 19F NMR (CDCl3, C6F6 internal): δ =
–89.7 (m, 1F) ppm. 31P{1H} NMR (CDCl3): δ = 43.8 [dd, 1P, 4JPF, 3JPP ≈ 7.2 Hz, P6], 37.0 [dd, 1P, 3JPF
3
= 14.2 Hz, JPP = 7.1 Hz, P1] ppm. HRMS: calcd. for С20H19FP2S2 [M] 404.0382; found 404.0380;
Anal. calcd. for С20H19FP2S2: C, 59.39; H, 4.74; S, 15.87; found: C, 59.03; H, 4.55; S, 15.80. The X-
ray molecular structure is depicted in Fig. 1.
5.3. (3,5-Difluorophenyl)(methyl)phenylphosphine (17)
Compounds 2 (0.167 g, 0.851 mmol), 4 (0.168 g, 1.272 mmol), and C6D6 (0.47 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.09 kPa), allowed to warm to ambient temperature and kept at 150 °C for 30 h, 175 °C for 16
h and then 200 °C for 50 h while NMR spectra were periodically recorded. The volatile components
were distilled off in vacuo (0.09 kPa) while the bath temperature was increased to 100 °C and 17 was
obtained as a colourless liquid by vacuum distillation at bath temperatures increasing from 120 to 130 °C
(0.14 g, 70%). 1H NMR (C6D6): δ = 7.29–7.35 (m, 2H, CArH), 7.10–7.13 (m, 3H, CArH), 6.81–6.87 (m,
2H, CArH), 6.46 [ttd, 1H, 3JHF = 8.9 Hz, 4JHH = 2.3 Hz, 4JHP = 0.4 Hz, H4], 1.26 [d, 3H, 2JHP = 4.3 Hz,
13
1
3
3
CH3] ppm. C NMR (C6D6): δ = 163.3 [ddd, JCF = 251.4 Hz, JCP = 11.6 Hz, JCF = 7.9 Hz, C3,5],
146.8 [dt, 1JCP = 20.0 Hz, 3JCF = 6.2 Hz, C1], 138.7 [d, 2JCP = 12.9 Hz, C2’,6’], 132.8 [d, 1JCP = 20.1 Hz,
3
2
2
4
C1’], 129.3 (s, C4’), 128.9 [d, JCP = 7.0 Hz, C3’,5’], 114.2 [ddd, JCF, JCP ≈ 18.2 Hz, JCF = 6.3 Hz,
2
4
1
C2,6], 103.6 [td, JCF = 25.4 Hz, JCP = 1.1 Hz, C4], 11.9 [d, 3H, JCP = 15.4 Hz, CH3] ppm.19F NMR
18
Page 21 of 31

(C6D6): δ = –107.5 [ddd, 2F, 3JFH = 8.7, 6.6 Hz, 5JFН = 1.2 Hz, F3,5] ppm. 31P{1H} NMR (C6D6): δ = –23.6
(m, 1P) ppm. NMR data are consistent with those previously reported [30].
5.4. (2,5-Difluorophenyl)(methyl)phenylphosphine (18)
Compounds 1 (0.540 g, 2.753 mmol), 5 (0.545 g, 4.130 mmol), and C6D6 (0.05 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.05 kPa), allowed to warm to ambient temperature and kept at 200 °C for 11 h while NMR
spectra were periodically recorded (Scheme 1). The volatile components were distilled off in vacuo
(0.07 kPa) while the bath temperature was increased to 100 °C and 18 was obtained as a colourless
1
liquid by vacuum distillation at bath temperatures increasing from 100 to 130 °C (0.465 g, 72%). H
NMR (CDCl3): δ = 7.51–7.57 (m, 2H, CArH), 7.38–7.43 (m, 3H, CArH), 6.94–7.00 (m, 2H, CArH),
6.82–6.88 (m, 1H, CArH), 1.68 [d, 3H, 2JHP = 4.6 Hz, CH3] ppm. 13C NMR (CDCl3): δ = 159.8 [dd, 1JCF
= 240.8 Hz, 2JCP = 12.0 Hz, C2], 158.6 [d, 1JCF = 244.3 Hz, C5], 136.9 [d, 2JCP = 11.1 Hz, C2’,6’], 132.4
[d, 1JCP = 20.2 Hz, C1’], 129.1 (s, C4’), 128.5 [d, 3JCP = 6.9 Hz, C3’,5’], 118.3 [dd, 2JCF = 24.0 Hz, 3JCP
=
12.1 Hz, C3], 118.3 [d, 2JCF = 24.0 Hz, C4], 116.4 [dd, J = 24.3, 8.7 Hz, C1 or C6], 116.1 [dd, J = 26.6, 7.9
1
Hz, C6 or C1], 10.7 [d, 3H, JСP = 13.6 Hz, CH3] ppm. 19F NMR (CDCl3): δ = –112.6 [dm, 1F, 3JFP = 40.4
3
Hz, F2], 43.2 (m, 1F, F5) ppm. 31P{1H} (CDCl3): δ = –35.6 [d, 1P, JPF = 40.4 Hz] ppm. HRMS: calcd. for
С13H11F2P [M] 236.0561; found 236.0567; Anal. calcd. for С13H11F2P: C, 66.11; H, 4.69; F, 16.09;
found: C, 66.52; H, 4.87; F, 15.60.
5.5. (2,3-Difluorophenyl)diphenylphosphine (19)and (2,6-difluorophenyl)diphenylphosphine(20)
Compounds 2 (0.437 g, ~1.7 mmol), 3 (0.335 g, 2.54 mmol), and C6D6 (0.18 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.04 kPa), allowed to warm to ambient temperature and then kept at 180 °C for 26 h while
NMR spectra were periodically recorded. The volatile components were distilled off in vacuo (0.04
kPa), the residue was separated by TLC (Sorbfil, hexane, 2 times) to yield:
1
Phosphine 19 (RF = 0.4, 0.182 g, 36%), white crystals; m.p. 112–113 °C. H NMR (CDCl3): δ =
7.30–7.40 (m, 10H, CArH), 7.15 [ddddd, 1H, 3JHF = 10.0 Hz, 3JHH = 8.3 Hz, 4JHF = 7.5 Hz, 4JHH = 1.6 Hz,
5JHP = 0.8 Hz, H4], 6.98 [ddddd, 1H, 3JHH = 8.3 Hz, 3JHH = 7.7 Hz, 4JHF = 4.6 Hz, 4JHP = 1.3 Hz, 5JHF
0.7 Hz, H5], 6.56 [ddddd, 1H, 3JHH = 7.4 Hz, 3JHP = 5.4 Hz, 4JHF = 4.5 Hz, 4JHH = 1.6 Hz, 5JHF = 1.4 Hz,
=
13
1
2
2
H6] ppm. C NMR (CDCl3): δ = 151.8 [ddd, JCF = 247.3 Hz, JCP = 15.1 Hz, JCF = 12.4 Hz, C2],
19
Page 22 of 31

2
150.4 [ddd, 1JCF = 250.6 Hz, JCF = 14.2 Hz, 3JCP = 3.4 Hz, C3], 134.8 [dd, 2JCP = 10.5, 5JCF = 1.1 Hz,
1
3
C2’,6’], 133.8 [d, JCP = 20.7 Hz, C1’], 129.3 (s, C4’), 128.7 [d, JCP = 7.3 Hz, C3’,5’], 128.6–128.7 (m,
C6), 127.9 [dd, 1JCP = 20.6 Hz, 2JCF = 16.2 Hz, C1], 124.4 [ddd, 3JCF = 6.3 Hz, J = 4.3 Hz, 1.6 Hz, C5],
118.0 [d, 2JCF = 17.2 Hz, C4] ppm. 19F NMR (CDCl3): δ = –130.4 [dddd, 1F, 3JFP = 50.2 Hz, 3JFF = 22.1
Hz, 3JFH = 8.3 Hz, 4JFH = 6.0 Hz, F2], –139.4 [ddddd, 1F, 3JFF = 22.2 Hz, 3JFH = 8.4 Hz, 4JFH = 4.5 Hz,
5
4JFP = 3.6 Hz, JFH = 1.0 Hz, F3] ppm. 31P{1H} NMR (CDCl3): δ = –18.3 [dm, 1P, 3JPF ≈ 50 Hz] ppm.
HRMS: calcd. for С18H13F2P [M] 298.0718; found 298.0719; Anal. calcd. for С18H13F2P: C, 72.48; H,
4.39; F, 12.74; found: C, 72.54; H, 4.37; F, 12.70.
Phosphine 20 (RF = 0.3, 0.030 g, 6%). 1H NMR (CDCl3): δ = 7.33–7.49 (m, 11H, CArH), 6.9 [ddd,
3
3
19
3
2H, JHF, JHH ≈ 7.9 Hz, 4JHH = 2.0 Hz, H3,5] ppm. F NMR (CDCl3): δ = –99.1 [ddd, 2F, JFP = 41.8
3
4
31
3
Hz, JFH, JFН ≈ 6.9 Hz, F2,6] ppm. P{1H} NMR (CDCl3): δ = –28.0 [tm, 1P, JPF ≈ 42.0 Hz] ppm.
HRMS: calcd. for С18H13F2P [M] 298.0718; found 298.0717. NMR data are consistent with those
previously reported [31,32].
5.6. Oxidation of phosphine 19 to phosphineoxide 24
A mixture of 19 (0.016 g, 0.054 mmol), hydrogen peroxide (50%) (0.4 mL) and chloroform (4 mL)
was stirred for 2 h at 20 °C. A chloroform solution was centrifuged off, the solvent was distilled off in
vacuo (0.07 kPa), the residue was purified by TLC (Sorbfil, diethyl ether, RF = 0.5) to yield
phosphineoxide 24 (0.015 g, 86%), white crystals, m.p. 111–112 °C. 1H NMR (CDCl3): δ = 7.43–7.83 (m,
11H, CArH), 7.37 (m, 1H, CArH), 7.20–7.29 (m, 1H, CArH) ppm. 13C NMR (CDCl3): δ = 150.6 [ddd, 1JCF
1
2
2
= 252.1 Hz, 2JCF = 13.3 Hz, 3JCP = 2.5 Hz, C3], 150.4 [ddd, JCF = 252.0 Hz, JCF = 13.9 Hz, JCP = 9.9
4
3
6
1
Hz, C2], 132.4 [d, JCP = 2.8 Hz, C4’], 131.6 [dd, JCP = 10.6 Hz, JCF = 1.7 Hz, C3’], 131.5 [d, JCP
=
108.8 Hz, C1’], 129.1 (m, C6), 128.6 [d, 2JCP = 12.8 Hz, C2’], 125.0 [ddd, 3JCF = 12.3 Hz, 3JCP = 6.0 Hz,
1
2
2
4JCF = 4.5 Hz, C5], 123.0 [dd, JCP = 96.9 Hz, JCF = 15.2 Hz, C1], 121.8 [d, JCF = 17.6 Hz, C4] ppm.
19F NMR (CDCl3): δ = –126.2 [dt, 1F, 3JFF ≈ 22.7 Hz, 4JFH ~ 3JFP ≈ 6.7 Hz, F2], –137.3 [dm, 1F, 3JFF ≈
3
22.7 Hz, F3] ppm. 31P{1H} NMR (CDCl3): δ = 23.9 [d, 1P, JPF ≈ 6.7 Hz] ppm. HRMS: calcd. for
С18H12F2OP [M–H] 313.0588; found 313.0587.
5.7. (3,5-Difluorophenyl)diphenylphosphine (21) and (3,5-difluorophenyl)diphenylphosphineoxide (23)
Compounds 2 (0.091 g, 0.352 mmol), 4 (0.093 g, 0.705 mmol), C6H6 (0.6 mL) and C6D6 (0.05 mL)
were condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
20
Page 23 of 31

vacuum (0.08 kPa), allowed to warm to ambient temperature and kept at 175 °C for 251 h and then 196 °C
for 172 h while NMR spectra were periodically recorded (Scheme 2). The volatile components were
distilled off in vacuo (0.08 kPa), the residue was separated by TLC (Sorbfil) to sequentially isolate:
19
Phosphine 21 (eluent: chloroform–hexane, 1:2, RF = 0.4, 0.007 g, 7%), colorless liquid. F
NMR (CDCl3): δ = –110.5 (m, 2F, F3,5) ppm. 31P{1H} NMR (CDCl3): δ = –3.4 (br. s, 1P) ppm. NMR
data are consistent with those previously reported [33].
Phosphineoxide 23 (eluent: acetone, Rf = 0.8, and then acetone–hexane, 1:1, RF = 0.5; 0.008 g, 7%),
white crystals. 1H NMR (CDCl3): δ = 7.42–7.70 (m, 10H, C6H5), 7.2 (m, 2H, H2), 6.95 [tt, 1H, 3JHF
=
4
8.6 Hz, JHH = 2.3 Hz, H4] ppm. 19F NMR (CDCl3): δ = –105.3 (m, 2F, F3,5) ppm. 31P{1H} NMR
(CDCl3): δ = 27.6 (br. s, 1P) ppm. HRMS: calcd. for С18H12F2OP [M–H] 313.0588; found 313.0589.
NMR data are consistent with those previously reported [34].
5.8. (3,5-Difluorophenyl)diphenylphosphine (21)
Compounds 2 (0.320 g, 1.240 mmol), 4 (0.274 g, 2.072 mmol) and C6D6 (0.05 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under vacuum
(0.05 kPa), allowed to warm to ambient temperature and kept at 240 °C for 22 h while NMR spectra
were periodically recorded (Scheme 2). The volatile components were distilled off in vacuo (0.07
kPa), while the bath temperature was increased to 170 °C and 21 was obtained as a colourless liquid
by vacuum distillation at bath temperatures increasing from 170 to 185 °C (0.13 g, 35%).
5.9. (2,5-Difluorophenyl)diphenylphosphine (22) and (2,5-difluorophenyl)diphenylphosphineoxide (25)
Compounds 2 (0.128 g, 0.5 mmol), 5 (0.132 g, 1.0 mmol), C6H6 (0.45 mL) and C6D6 (0.05 mL)
were condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.08 kPa), allowed to warm to ambient temperature and kept at 175 °C for 251 h and then 196
°C for 98 h (Scheme 2). The volatile components were distilled off in vacuo (0.08 kPa), the residue
was separated by TLC (Sorbfil) to sequentially isolate:
Phosphine 22 (eluent: chloroform–hexane, 1:2, RF = 0.6, 0.053 g, 36%), colorless liquid. 1H NMR
13
(CDCl3): δ = 7.41–7.48 (m, 10H, CArH), 7.00–7.08 (m, 2H, CArH), 6.58–6.66 (m, 1H, CArH) ppm. C
1
2
4
1
NMR (CDCl3): δ = 159.8 [ddd, JCF = 241.6 Hz, JCP = 14.8 Hz, JCF = 2.1 Hz, C2], 158.7 [dd, JCF
=
244.5 Hz, 4JCF = 2.1 Hz, C5], 134.7 [dd, 2JCP = 10.6 Hz, 4JCF = 1.3 Hz, C2’,6’], 133.7 [d, 1JCP = 20.7 Hz,
C1’], 129.5 (s, C4’), 128.9 [d, 3JCP = 7.4 Hz, C3’,5’], 127.6 [ddd, 2JCF = 22.5 Hz, 1JCP = 21.5 Hz, 3JCF = 5.3
21
Page 24 of 31

Hz, C1], 120.0 [ddd, 2JCF = 24.6 Hz, 2JCP = 5.3, 3JCF = 3.2 Hz, C6], 117.2 [dd, 2JCF = 24.4 Hz, 3JCF = 8.7
Hz, C4], 116.3 [ddd, 2JCF = 26.4 Hz, 3JCF = 8.1 Hz, 3JCP = 1.3 Hz, C3] ppm. 19F NMR (CDCl3): δ = –108.2
[ddm, 1F, 3JFP = 51.9 Hz, 5JFF ≈ 18.0 Hz, F2], –116.1 [dm, 1F, 5JFF ≈ 18.0 Hz, F5] ppm. 31P{1H} (CDCl3): δ =
–18.0 [d, 1P, 3JPF = 51.9 Hz] ppm. HRMS: calcd. for С18H13F2P [M] 298.0718; found 298.0717; Anal.
calcd. for С18H13F2P: C, 72.48; H, 4.39; found: C, 72.77; H, 4.36.
Phosphineoxide 25 (eluent: acetone, RF = 0.8, and then chloroform, 5 times, RF = 0.2; 0.008 g,
5%), white crystals, m.p. 135–136 °C. 1H NMR (CDCl3): δ = 7.70 [br. dd, 4H, 3JHP = 12.9 Hz, 3JHH = 7.7 Hz,
3
4
5
H2’,6’], 7.57 (m, 1H, H4), 7.53 [ttd, 2H, JHH = 7.5 Hz, JHH, JHP = 1.5–2.0 Hz, H4’], 7.44 [dddd, 4H,
4
5
3
3JHH = 7.5–7.7 Hz, JHP = 3.0–3.5 Hz, JHH ≈ 1.0 Hz, H3’,5’], 7.19 [dm, 1H, JHF = 9.0 Hz, H3], 7.02
[dddd, 1H, 3JHF, 3JHP = 8.6–8.8 Hz, 4JHF = 5.3 Hz, 4JHH = 4.7 Hz, H6] ppm. 13C NMR (CDCl3): δ = 158.6
1
3
4
[ddd, 1JCF = 246.6 Hz, 2JCP = 14.2 Hz, 4JCF = 2.4 Hz, C2], 158.5 [ddd, JCF = 246.3 Hz, JCP, JCF = 2.0–
2.5 Hz, C5], 132.3 [d, 4JCP = 2.8 Hz, C4’], 131.6 [dd, 3JCP = 10.6 Hz, 6JCF = 1.5 Hz, C3’], 131.2 [d, 1JCP
=
108.8 Hz, C1’], 128.5 [d, 2JCP = 12.8 Hz, C2’], 122.1 [ddd, 1JCP = 97.6 Hz, 2JCF = 21.8 Hz, 3JCF = 5.8 Hz,
C1], 121.2 [ddd, 2JCF = 24.3 Hz, 3JCF = 8.9 Hz, 4JCP = 2.0 Hz, C4], 120.8 [ddd, 2JCF = 25.4 Hz, 3JCF = 5.7
3
2
3
3
19
Hz, JCP = 4.9 Hz, C3], 117.6 [ddd, JCF = 26.1 Hz, JCF, JCP ≈ 7.2 Hz, C6] ppm. F (CDCl3): δ = –
107.3 [dm, 1F, 5JFF = 18.9 Hz, F2], –118.2 [dm, 1F, 5JFF = 18.9 Hz, F5] ppm. 31P{1H} (CDCl3): δ = 23.7
3
4
[dd, 1P, JPF, JPF = 2.0–3.0 Hz] ppm. HRMS: calcd. for С18H12F2OP [M–H] 313.0588; found
313.0591; Anal. calcd. for С18H13F2OP: C, 68.79; H, 4.17; F, 12.09; found: C, 69.16; H, 4.23; F, 12.02.
5.10. (2,5-Difluorophenyl)diphenylphosphine (22)
Compounds 2 (0.235 g, 0.910 mmol), 5 (0.240 g, 1.820 mmol) and C6D6 (0.13 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.05 kPa), allowed to warm to ambient temperature and kept at 240 °C for 28 h while NMR
spectra were periodically recorded (Scheme 2). The volatile components were distilled off in vacuo
(0.07 kPa), while the bath temperature was increased to 170 °C and 22 was obtained as a colourless
liquid by vacuum distillation at bath temperatures increasing from 170 to 180 °C (0.20 g, 74%).
5.11. Oxidation of posphine (22) to phosphineoxide (25)
A mixture of 22 (0.053 g, 0.178 mmol), hydrogen peroxide (14%) (0.2 mL) and chloroform (3 mL)
was stirred for 48 h at 20 °C. The chloroform solution was centrifuged off, the solvent was distilled off in
vacuo (0.08 kPa) to give oxide 25 (0.023 g, 40%).
22
Page 25 of 31

5.12. [4-(Diphenylphosphinyl)-2,3,5,6-tetrafluorophenyl]diphenylphosphine (26)
Compounds 2 (0.348 g, 1.348 mmol), 6 (0.126 g, 0.675 mmol), and C6D6 (0.09 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.09 kPa), allowed to warm to ambient temperature and then kept at 150 °C for 4 h. The
volatile components were distilled off in vacuo (0.09 kPa), the residue was purified by TLC (Sorbfil,
chloroform, RF = 0.9, and then chloroform–hexane, 1:4, 4 times, RF = 0.5) to yield phosphine 26
(0.207 g, 59%), white crystals, m.p. 203–204 °C (203–204 °C [35]). 1H NMR (CDCl3): δ = 7.40–7.48
(m, 8H, CArH), 7.34–7.39 (m, 12H, CArH) ppm. 19F (CDCl3, C6F6 internal): δ = –128.9 [dm, 4F, 3JFP =
36.7 Hz] ppm. 31P{1H} (CDCl3): δ = –23.1 [m, 2P, 3JPF = 36.7 Hz] ppm. HRMS: calcd. for С30H20F4P2
[M] 518.0971; found 518.0966.
5.13. Diphenyl(2,3,5,6-tetrafluorophenyl)phosphine (27)
Compounds 2 (0.735 g, 2.85 mmol), 7 (0.718 g, 4.27 mmol), and C6D6 (0.05 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under vacuum
(0.08 kPa), allowed to warm to ambient temperature and then kept at 150 °C for 9 h while NMR spectra
were periodically recorded. The volatile components were distilled off in vacuo (0.08 kPa) while the bath
temperature was increased to 130 °C and phosphine 27 was obtained as a colorless liquid by vacuum
distillation (0.05 kPa) at a bath temperature from 130 to 150 °C (yield 0.57 g, 60%). 1H NMR (CDCl3): δ =
7.44–7.50 (m, 4H, CArH), 7.35–7.41 (m, 6H, CArH), 7.12 [tt, 1H, 3JHF = 9.3 Hz, 4JHF = 7.4 Hz, H4] ppm. 13C
NMR (CDCl3): δ = 147.8 [dm, 1JCF = 247.3 Hz, C2,6], 146.0 [dddd, 1JCF = 251.1 Hz, 2JCF = 16.4 Hz, 3JCP = 9.2
Hz, 4JCF = 4.3 Hz, C3,5], 133.0 [d, 1JCP = 21.1 Hz, C1’], 129.2 (s, C3’,5’ or C4’), 128.6 [d, 2JCP = 7.2 Hz,
1
2
2
C2’,6’], 121.5 (s, C4’ or C3’,5’), 117.1 [dt, JCP = 38.4 Hz, JCF = 21.0 Hz, C1], 108.0 [t, JCF = 22.7 Hz,
19
3
C4] ppm. F NMR (CDCl3, C6F6 internal): δ = –129.5 [dm, 2F, JFP = 38.3, F2,6], –138.9 (m, 2F, F3,5)
ppm. 31P{1H} NMR (CDCl3): δ = –23.9 [t, 1P, 3JPF = 38.3 Hz] ppm. HRMS: calcd. for С18H11F4P [M]
334.0529; found 334.0531; Anal. calcd. for С18H11F4P: C, 64.68; H, 3.32; found: C, 64.49; H, 3.42.
5.14. Diphenyl[2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenyl]phosphine (28)
Compounds 2 (0.360 g, 1.40 mmol), 8 (0.494 g, 2.09 mmol), and C6D6 (0.05 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
23
Page 26 of 31

vacuum (0.08 kPa), allowed to warm to ambient temperature and then kept for 142 h while NMR
spectra were periodically recorded. The volatile components were distilled off in vacuo (0.08 kPa)
while the bath temperature was increased to 130 °C and phosphine 28 was obtained as a colourless
liquid by vacuum distillation (0.08 kPa) at a bath temperature from 155 to 160 °C. The resultant residue
was crystallized from hexane (6 mL), dried in vacuo (0.08 kPa) at room temperature for 1 h to give
phosphine 28 (0.30 g, 53%) as white crystals, m.p. 50–51 °C. 1H NMR (CDCl3): δ = 7.36–7.49 (m, 10H,
C6H5) ppm. 13C NMR (CDCl3): δ = 147.9 [dm, 1JCF = 249.5 Hz, C2,6], 143.9 [ddm, 1JCF = 262.8 Hz, J =
4
2
5
18.3 Hz, C3,5], 133.2 [dt, JCF = 1.0 Hz, C1’], 132.5 [dt, JCP = 10,1 Hz, JCF = 2.6 Hz, C2’,6’], 129.8
(br. s, C4’), 128.9 [d, 3JCP = 7.6 Hz], 121.6–122.6 (m, CF3, C4), 110.9 [dtm, 1JCP = 35.0 Hz, 2JCF = 12.6
Hz, C1] ppm. 19F NMR (CDCl3): δ = –57.8 [t, 3F, 4JFF = 21.6 Hz, CF3], –127.5 [dm, 2F, 3JFP = 33.9 Hz,
4
31
3
F2,6], –140.9 [qm, 2F, JFF = 21.6 Hz, F3,5] ppm. P{1H} NMR (CDCl3): δ = –21.6 [t, 1P, JPF = 33.9
Hz] ppm. HRMS: calcd. for С19H10F7P [M] 402.0403; found 402.0405; Anal. calcd. for С19H10F7P: C,
56.73; H, 2.51; F, 33.06; found: C, 56.37; H, 2.62; F, 32.79.
5.15. 4-(Diphenylphosphinyl)-2,3,5,6-tetrafluoropyridine (29)
Compounds 2 (0.380 g, 1.47 mmol), 9 (0.223 g, 1.32 mmol), and C6D6 (0.05 mL) were
condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was sealed under
vacuum (0.08 kPa), allowed to warm to ambient temperature and then kept for 24 h at room
temperature. The volatile components were distilled off in vacuo (0.08 kPa) while the bath
temperature was increased to 130 °C and phosphine 29 was obtained as a colourless liquid by vacuum
distillation (0.08 kPa) at a bath temperature from 155 to 160 °C (0.420 g, 95%). 19F NMR (CСl4): δ = –
31
3
92.0 (m, 2F, F2,6), –131.8 (m, 2F, F3,5) ppm. P{1H} NMR (CСl4): δ = –19.7 [t, 1P, JPF = 26.6 Hz]
ppm. NMR data are consistent with those previously reported [4].
5.16. Typical procedure for kinetic experiments
Compound 1 or 2 (0.100.15 g, 0.500.60 mmol), polyfluoroarene 3 or 4 (0.130.15 g,
1.001.40 mmol), and C6D6 (0.150.30 mL) were condensed into an evacuated NMR tube cooled with
liquid nitrogen. The tube was sealed under vacuum (0.07 kPa), allowed to warm to ambient
temperature and then kept at the temperature of the kinetic measurement (see Schemes 4 – 7) while
periodically recording NMR spectra.
24
Page 27 of 31

5.17. Competitive reactions of 4 and 5 with 2
Compounds 2 (0.620 g, 2.40 mmol), 4 (0.275 g, 2.08 mmol), 5 (0.272 g, 2.06 mmol), and C6D6
(0.11 mL) were condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was
sealed under vacuum (0.08 kPa), allowed to warm to ambient temperature and then kept at the
temperature specified in Scheme 5 while NMR spectra were periodically recorded.
5.18. Competitive reactions of 3 and 4 with PhMePH
Compounds 1 (0.061 g, 0.49 mmol), 3 (0.130 g, 0.98 mmol), 4 (0.130 g, 0.98 mmol), and C6D6
(0.27 mL) were condensed into an evacuated NMR tube cooled with liquid nitrogen. The tube was
sealed under vacuum (0.09 kPa), allowed to warm to ambient temperature and then kept at the
temperature specified in Scheme 7 while NMR spectra were periodically recorded.
5.19. Reaction between 5 and Ph2PLi (Scheme 8)
Compound 5 (0.132 g, 0.10 mmol), C6H6 (0.7 mL), and C6D6 (0.05 mL) were condensed into an
evacuated reaction vessel, charged with Ph2PLi (0.077 g, ~0.40 mmol) and cooled with liquid
nitrogen. The reaction vessel was sealed under vacuum (0.09 kPa) and allowed to warm to ambient
19
temperature. The resulting solution was stirred at 20 °C for 1 h, filtered and was shown by F NMR
spectroscopy to contain phospines 22, 19, and 30 in the 4.7:1.0:1.0 ratio. Phosphine 30: 19F NMR
(CD3)2CO): δ = –132.2 [dm, 1F, 3JFF = 22.0 Hz, F4], –140.1 [dm, 1F, 3JFF = 22.0 Hz, F3] ppm. 31P{1H}
4
5
NMR ((CD3)2CO): δ = –13.8 [dd, 1P, JPF, JPF ≈ 6.0 Hz] ppm. The mixture was separated by the
stepped TLC: first, eluating with CHCl3–hexane 1:2 to isolate the fraction with RF = 0.8, then this
fraction was eluated two times with CHCl3–hexane 1:10 to obtain fraction A (RF = 0.6, 0.002 g),
consisting of 30 and its oxide 31 (11:1), and, at last, two times with CHCl3–hexane 1:20 to obtain
fraction B (RF = 0.5, 0.002 g), consisting of 19 and its oxide 24 (1.0:1.3).
A mixture of fraction A (0.002 g), hydrogen peroxide (14%) (0.2 mL) and acetone (1 mL) was
stirred for 24 h at 20 °C. Water (1 mL) was added, a precipitate was centrifuged off, washed with
water (1 mL) and dried in vacuum (0.08 kPa) to give phosphineoxide 31 (0.002 g, 98%), white crystals
thermally decomposing without melting.1H NMR ((CD3)2CO): δ = 8.04–8.10 (m, 1H, CArH), 7.91
3
[dddd, 1H, JHF = 8.2 Hz, J = 3.5, 2.7, 0.8, CArH], 7.45–7.75 (m, 10H, CArH) ppm. 19F NMR
((CD3)2CO): δ = –132.5 [dd, 1F, 3JFF = 22.3 Hz, 3JFH = 8.2 Hz, F4], –137.3 [dddd, 1F, 3JFF = 22.3 Hz,
25
Page 28 of 31

4
3JFH = 10.5, JFH = 6.6, J = 3 Hz, F3] ppm. 31P{1H} NMR ((CD3)2CO): δ = 29.3 (br. s, 1P) ppm.
HRMS: calcd. for С18H11F2OP [M–2H] 312.0510; found 312.0506.
A mixture of fraction B (0.002 g) and acetone (0.5 mL) was stirred for 24 h at 20 °C. The volatile
components were distilled off in vacuo (0.08 kPa) to give phosphineoxide 24 (0.002 g, 98%). 1H and 19F
NMR data match those of the specimen described above.
Acknowledgment
This research was in part supported by the Siberian Division of the Russian Academy of Sciences (the
project No. 59) and by Russian Foundation of Basic Research (the project No. 14-03-00108).
References
[1] (a) C.L. Pollock, G.C. Saunders, E.C.M.S. Smyth, V.I. Sorokin, J. Fluor. Chem. 129 (2008) 142–166;
(b) L.I. Goryunov, J. Grobe, V.D. Shteingarts, Collect. Czech. Chem. Сommun. 73 (2008) 1612–1622.
[2] V.V. Kormachev, T.V. Vasil'eva, J. Gen. Chem. (Engl. Transl.) 58 (1988) 681–686.
[3] L.I. Goryunov, S.I. Zhivetyeva, G.A. Nevinsky, V.D. Shteingarts, ARKIVOC 8 (2011) 185–191.
[4] Yu.A. Veits, N.B. Karlstedt, A.V. Chuchuryukin, I.P. Beletskaya, Russ. J. Org. Chem. 36 (2000)
750–756.
[5] M. Nieuwenhuyzen, G.C. Saunders, V.I. Sorokin, Mendeleev Commun. 16 (2006) 171–172.
[6] K. Issleib, A. Tzschach, H.-U. Blok, Chem. Ber. 101 (1968) 2931–2937.
[7] S.Y. Coote, G.J. Dawson, C.G. Frost, J.M.J. Willioms, Synlett 7 (1993) 509–510.
[8] L.I. Goryunov, J. Grobe, V.D. Shteingarts, R. Mews, E.-U. Würthwein, Russ. J. Org. Chem. 45
(2009) 1860–1862.
[9] (a) L.I. Goryunov, J. Grobe, B. Krebs, A. Lindemann, C. Muck-Lichtenfeld, V.D. Shteingarts,
E.-U. Würthwein, Eur. J. Chem. 6 (2000) 4612–4622;
(b) L.I. Goryunov, J. Grobe, V.D. Shteingarts, E.-U. Würthwein, Russ. J. Org. Chem. 45 (2009)
1859–1861.
[10] L.I. Goryunov, J. Grobe, B. Krebs, V.D. Shteingarts, M.U. Triller, Z. Anorg. Allg. Chem. 628
(2002) 1770–1779.
[11] R.M. Bellabarba, M. Nieuwenhuyzen, G.C. Saunders, Organometallics 22 (2003) 1802–1810.
[12] L.I. Goryunov, J. Grobe, D. Le Van, E. Lork, R. Mews, V.D. Shteingarts, E.-U. Würthwein, Eur.
J. Org. Chem. 6 (2010) 1111–1123.
26
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