From hypervalent xenon difluoride and aryliodine(III) difluorides to onium salts: Scope and limitation of acidic fluoroorganic reagents in the synthesis of fluoroorgano xenon(II) and iodine(III) onium salts

Article abstract of DOI:10.1016/j.jfluchem.2006.05.008

Fluorinated organodifluoroboranes R_fBF₂ are in general suitable reagents to transform XeF₂ and RIF₂ into the corresponding onium tetrafluoroborate salts [R_fXe][BF₄] and [R(R_f)I][BF₄], respectively. (4-C₅F₄N)BF₂ and trans-CF₃CF{double bond, long}CFBF₂ which represent boranes of high acidity form no Xe-C onium salts in reactions with XeF₂ but give the desired iodonium salts with RIF₂ (R = C₆F₅, o-, m-, p-C₆FH₄). The reaction of (4-C₅F₄N)BF₂ with XeF₂ ends with a XeF₂-borane adduct. C₆F₅Xe(4-C₅F₄N), the first Xe-(4-C₅F₄N) compound, was obtained when C₆F₅XeF was reacted with Cd(4-C₅F₄N)₂. We describe the synthesis of (4-C₅F₄N)IF₂ and reactions of (4-C₅F₄N)IF₂ and C₆F₅IF₂ with (4-C₅F₄N)BF₂. Analogous to [(4-C₅F₄N)₂I][BF₄] and [C₆F₅(4-C₅F₄N)I][BF₄] aryl(perfluoroalkenyl)iodonium salts [R(R′)I][BF₄] were obtained from RIF₂ (R = C₆F₅, o-, m-, p-C₆FH₄) and R′BF₂ (R′ = trans-CF₃CF{double bond, long}CF, CF₂{double bond, long}CF). The gas phase fluoride affinities pF^- of selected fluoroorganodifluoroboranes R_fBF₂ and their hydrocarbon analogs are calculated (B3LYP/6-31+G^*) and discussed with respect to their potential to introduce R_f-groups into hypervalent EF₂ bonds. Four aspects which influence the transformation of hypervalent EF₂ bonds (E = Xe, R′I) under the action of Lewis acidic reagents RAF_n-1 (A = B, P; n = 3, 5) into the corresponding [RE][AF_n+1] salts are presented and the important role of the acidity is emphasized. Fluoride affinities may help to plan the introduction of organo groups into EF₂ moieties and to expand the types of acidic reagents. Thus C₆H₅PF₄ with a pF^- value comparable to that of R_fBF₂ compounds is able to introduce the C₆H₅ group into RIF₂ (R = C₆F₅, p-C₆FH₄).

Full text of DOI:10.1016/j.jfluchem.2006.05.008

Journal of Fluorine Chemistry 127 (2006) 1311–1323
www.elsevier.com/locate/fluor
From hypervalent xenon difluoride and aryliodine(III) difluorides
to onium salts: Scope and limitation of acidic fluoroorganic
reagents in the synthesis of fluoroorgano xenon(II) and
iodine(III) onium salts
*
Anwar Abo-Amer, Hermann-Josef Frohn , Christoph Steinberg, Ulrich Westphal
University Duisburg-Essen, Inorganic Chemistry, D-47048 Duisburg, Germany
Received 24 March 2006; received in revised form 8 May 2006; accepted 11 May 2006
Available online 16 May 2006
ˇ
Dedicated to Professor Boris Zemva.
Abstract
Fluorinated organodifluoroboranes RfBF2 are in general suitable reagents to transform XeF2 and RIF2 into the corresponding onium
tetrafluoroborate salts [RfXe][BF4] and [R(Rf)I][BF4], respectively. (4-C5F4N)BF2 and trans-CF3CF CFBF2 which represent boranes of high
acidity form no Xe–C onium salts in reactions with XeF2 but give the desired iodonium salts with RIF2 (R = C6F5, o-, m-, p-C6FH4). The reaction of
(4-C5F4N)BF2 with XeF2 ends with a XeF2–borane adduct. C6F5Xe(4-C5F4N), the first Xe-(4-C5F4N) compound, was obtained when C6F5XeF
was reacted with Cd(4-C5F4N)2. We describe the synthesis of (4-C5F4N)IF2 and reactions of (4-C5F4N)IF2 and C6F5IF2 with (4-C5F4N)BF2.
Analogous to [(4-C5F4N)2I][BF4] and [C6F5(4-C5F4N)I][BF4] aryl(perfluoroalkenyl)iodonium salts [R(R0)I][BF4] were obtained from RIF2
(R = C6F5, o-, m-, p-C6FH4) and R0BF2 (R0 = trans-CF3CF CF, CF2 CF). The gas phase fluoride affinities pFꢀ of selected fluoroorganodi-
fluoroboranes RfBF2 and their hydrocarbon analogs are calculated (B3LYP/6-31+G*) and discussed with respect to their potential to introduce Rf-
groups into hypervalent EF2 bonds. Four aspects which influence the transformation of hypervalent EF2 bonds (E = Xe, R0I) under the action of
Lewis acidic reagents RAFnꢀ1 (A = B, P; n = 3, 5) into the corresponding [RE][AFn+1] salts are presented and the important role of the acidity is
emphasized. Fluoride affinities may help to plan the introduction of organo groups into EF2 moieties and to expand the types of acidic reagents.
Thus C6H5PF4 with a pFꢀ value comparable to that of RfBF2 compounds is able to introduce the C6H5 group into RIF2 (R = C6F5, p-C6FH4).
# 2006 Elsevier B.V. All rights reserved.
Keywords: XeF2; Xe–C compound; Iodonium salts; Perfluoropyridyldifluoroborane; Perfluoroalk-1-enyldifluoroboranes; Fluoride affinities
1. Introduction
salts were obtained under acidic conditions. Basic or low acidic
conditionsareappliedtoobtainthemoleculesR–Xe–YorR–Xe–
R0. The class of organoiodine difluorides, RIF2, belongs to the
large family of polyvalent iodine compounds [11–13]. XeF2 and
RIF2 have a hypervalent EF2 triad in common. Both compounds
have a C-trigonal bipyramidal arrangement with three electron
pairs (sum of bonding and lone pairs) in the equatorial plane and
two fluorine atoms in the apical positions. Generally, hypervalent
F–E–F triads are characterized by strong opposite partial charges
in the E–Fsubunits. The Mulliken charges, forexample, onE and
F can be used to indicate this phenomenon. From RHF
calculations (UGBS or LANL2DZ basis sets) of representative
molecules in the gas phase we can deduce the influence of the
equatorial group R in RIF2 on the Mulliken charge of I and F
(Table 1) Despite a comparable polarity of the E–F bonds
The basic knowledge about Xe–C compounds: preparation,
spectroscopic and structural properties, and reactivities, is
summarized in reviews [1,2]. Most of the original papers deal
with arylxenonium salts. Alk-1-enyl- [3,4] and alk-1-ynyl
xenonium salts [5,6] have been investigated to a lesser extent
until now. In addition to organylxenonium salts [RXe][Y], with a
2 center – 2 electron Xe–C bond, only few examples of Xe–C
moleculesofthetypesR–Xe–Y[7–9]orR–Xe–R0 [7,8,10]witha
3 center – 4 electron bond are presently known. All [RXe][Y]
* Corresponding author. Tel.: +49 203 379 3310; fax: +49 203 379 2231.
E-mail address: frohn@uni-duisburg.de (H.-J. Frohn).
0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2006.05.008

1312
A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
Table 1
e.g. fluorinated phenyl groups, and anions of low nucleophilicity
[1]. Surprisingly, till the present work no Xe–C compounds with
heteroaryl groups have been known. Thus we were interested to
introduce the 2,3,5,6-tetrafluoropyrid-4-yl group into XeF2.
Our first aim was the synthesis of [(4-C5F4N)Xe][BF4]. In an
analogous procedure to the synthesis of [C6F5Xe][BF4] we
investigated the reaction of XeF2 with (4-C5F4N)BF2 in the
temperature range from ꢀ78 to ꢀ36 8C in CH2Cl2 and 1,1,1,3,3-
pentafluoropropane (PFP). In case of CH2Cl2 under markedly
acidic conditions (XeF2 was slowly added to (4-C5F4N)BF2) the
solvent was attacked in part as shown by the formation of
CH2ClF, CH2F2, and CHCl2F. In CH2Cl2 as well as in PFP the
precipitation of a green or blue solid proceeded between ꢀ78 and
ꢀ36 8C. After separation, washing and drying the solid became
white and was characterized as a XeF2-(4-C5F4N)BF2 adduct
(Eq. (1)). The adduct, even if cooled at ꢁ ꢀ60 8C, is shock-
sensitive. The approximately 1:1 relation of the adduct is based
on the stoichiometry and the amount of consumed starting
materials. The coloration of the impure adduct arises from a by-
product, presumably an oxidation product of a (4-C5F4N)BFn
derivative. In a modified experiment the acid (4-C5F4N)BF2 was
added as very diluted CH2Cl2 solution in small portions to an
excess of XeF2. In that case the adduct did not exhibit the green
color and the solvent was not attacked.
Partial charges in hypervalent XeF2 and IF2 triads: Mulliken charges calculated
on RHF level using UGBS and LANL2DZ basis sets
Compounds with EF2 triad
UGBS
E
LANL2DZ
E
F
F
XeF2
0.95
1.44
1.61
1.10
1.14
0.98
ꢀ0.48
ꢀ0.50
ꢀ0.49
ꢀ0.54
ꢀ0.46
ꢀ0.55
1.31
1.78
1.54
1.38
1.46
1.30
ꢀ0.65
ꢀ0.64
ꢀ0.67
ꢀ0.69
ꢀ0.66
ꢀ0.69
IF3
C6F5IF2
C6H5IF2
CF3IF2
CH3IF2
different reactivities of XeF2 and RIF2 should not be astonishing
because RIF2 possesses a permanent dipole moment in contrast
to XeF2. Thus XeF2 [14] and C6F5IF2 [15] show distinct
intermolecular interactions in their single crystals.
The present work deals with influences, mainly the acidity of
the transfer reagent RfAFnꢀ1 (A = B, P; n = 3, 5), on the
substitution of fluorine in the hypervalent F–E–F triad by one
organyl group, preferentially
a perfluoroorganyl group.
Classical carbon nucleophiles, such as organolithium or
Grignard reagents, are no suitable candidates to substitute
fluorine in such a EF2 moiety. The low stability of these
reagents towards strong oxidizers and their preferential
handling in basic solvents like ethers, which can be attacked
by the reactive EF2 group, militate against these widely applied
carbon nucleophiles in reactions with EF2 compounds. Lewis
acidic organoelement fluorides RfAFnꢀ1 present a suitable type
of reagents for the introduction of fluoroorgano groups into
molecules bearing an EF2 group. Two aspects are important for
such acid-assisted nucleophilic substitutions: (a) the interaction
of the acid RfAFnꢀ1 with the EF2 triad weakens one E–F bond
and makes the access of the nucleophilic Rf group to the
electrophilic center E more easy and (b) as a consequence of the
interaction of the fluoro base with RfAFnꢀ1 the nucleofugality
of the Rf group will be increased. In a borderline description we
can illustrate this interaction as a transition from the molecule
RfAFnꢀ1 to the anion [RfAFn]ꢀ (Scheme 1). Aim of the present
work is to demonstrate the preparative potential of moderate
RfAFnꢀ1 Lewis acids, especially organodifluoroboranes, for the
synthesis of fluoroorgano onium salts of Xe(II) and I(III) and to
show different reactivities of XeF2 and RfIF2 if the acidity of
RfAFnꢀ1 is gradually varied.
The presence of [(4-C5F4N)Xe][BF4] in the solid product
could be excluded by chemical proofs (see below) and low tem-
perature Raman spectroscopy. The absence of a Xe–C bond is in
agreement with the lack of the generally very intensive Xe–C
vibration mode nearby the region 198–205 cmꢀ1 which is
characteristic for [C6F5Xe]+ salts [16]. Salts with the [XeF]+ or
[Xe2F3]+ cation can be excluded because of their instability in
CH2Cl2 and by the low temperature Raman spectrum (no band in
the region 596–619 cmꢀ1 ([XeF]+) or at 160 cmꢀ1 (Xe–F bend of
[Xe2F3]+)).Theproductcontainsnoband(ns(XeF2))at496 cmꢀ1
,
characteristic for non-coordinated XeF2. Two bands at 536 and
548 cmꢀ1 may belong to XeF2 coordinated at the borane. The
intensive band at 517 was attributed to (4-C5F4N)BF2. XeF2
coordinated at Ca2+ or Cd2+ in [M(XeF2)5][PF6]2 is characterized
byRamanbandsat522(strong)and545(weak)cmꢀ1 (Ca2+)[17].
Multi-NMR characterization of the adduct is not possible
because the solid could not be dissolved in aHF or EtCN at
ꢀ78 8C without decomposition.
We attribute the absence of the desired F-(4-C5F4N)
substitution in XeF2 to the cooperation of two influences: (a)
the high acidity of (4-C5F4N)BF2 (see Section 2.5) and (b) the
lower C-nucleophilicity of the (4-C5F4N) group relative to
fluorinated aryl groups.
2. Results and discussion
2.1. Three different approaches and results in experiments
to obtain 2,3,5,6-tetrafluoropyrid-4-ylxenon compounds
CH2Cl2 or PFP
XeF2 þ ð4-C5F4NÞBF2 ꢀ78ꢀto!ꢀ36 ꢂ
C
A larger number of arylxenonium salts is known. The stability
of such Xe–C compounds premises electron-poor aryl groups,
no formation of½ð4-C5F4NÞXeꢃ½BF4ꢃ
! ð4-C5F4NÞBF2 ꢄ XeF2
(1)
It should be mentioned that 2XeF2ꢄBF3 and XeF2ꢄBF3 were
reported, but have not been confirmed [18].
The acidic component of the adduct (4-C5F4N)BF2ꢄXeF2
reacted with [NMe4]F to the corresponding fluoroborate anion
Scheme 1.

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1313
and XeF2 was released (Eq. (2)). But the recovered amount of
the C6F5 group.
XeF2 was low (ꢅ11%) and varied from experiment to
experiment, caused by several side-reactions with the
easily oxidizable [(4-C5F4N)BF3]ꢀ anion under heterogeneous
conditions.
C6F5Xeð4-C5F4NÞ þ aHF ꢀ78ꢀꢂ!C=1 h
½C6F5Xeꢃ½FðHFÞnꢃ þ ð4-C5F4NÞH
(6)
CH2Cl2
ð4-C5F4NÞBF2 ꢄ XeF2 þ ½NMe4ꢃF ꢀ!
ꢀ40 ꢂC
½NMe4ꢃ½ð4-C5F4NÞBF3ꢃ þ XeF2
2.2. The substitution of fluorine in hypervalent bonds of
organoiodine difluorides using 2,3,5,6-tetrafluoropyrid-4-
ylboron difluoride
(2)
CH2Cl2
ð4-C5F4NÞBF2 ꢄ XeF2 þ 2½NBu4ꢃIꢀ50ꢀto!20 ꢂ
In order to compare the reactivity of the hypervalent EF2
triad in RfIF2 compounds with that in XeF2 we discuss reactions
of C6F5IF2 and (4-C5F4N)IF2 with (4-C5F4N)BF2. The new
heteroaryliodine difluoride (4-C5F4N)IF2 – subsequently used
as starting material – was obtained by the sequence of reactions
((7a)–(7c)). Recently we have published the formation of
[(C6F5)2I][BF4] [21] (Eq. (8)) and [C6F5(4-C5F4N)I][BF4] but
the latter as an admixture with [C6F5(4-C5F4N)I][(4-
C5F4N)BF3] [22] (Eq. (9)).
C
½NBu4ꢃ½ð4-C5F4NÞBF3ꢃ þ Xeo þ < ½NBu4ꢃF > þ I2
(3)
Above ꢀ50 8C the reaction of (4-C5F4N)BF2ꢄXeF2 with [NBu4]I
(Eq. (3)) resulted in evolution of Xe8 and the formation of 89%
[NBu4][(4-C5F4N)BF3], 8% [BF4]ꢀ, and 2% (4-C5F4N)H, but
no (4-C5F4N)I was detected as would be expected in case of a
[(4-C5F4N)Xe]+ salt (cf. [C6F5Xe][C6F5BF3] + [NMe4]I [19]).
The base-catalyzed transfer of the perfluoroorgano group – a
method introduced by Naumann [8] – did not lead to the desired
molecules (4-C5F4N)XeF or (4-C5F4N)2Xe. (4-C5F4N)2 was
formed as the main pyridyl species beside traces of (4-C5F4N)H
(Eq. (4)).
Et2O
ð4-C5F4NÞH þ BuLiꢀꢀ7!8 ꢂCð4-C5F4NÞLi þ Bu-H
(7a)
(7b)
(7c)
(8)
Et2O
ð4-C5F4NÞLi þ IClꢁꢀꢀ4!0 ꢂ ð4-C5F4NÞI þ LiCl
C
½½NMe4ꢃFꢃ
CH2Cl2 ꢀ60 ꢂC=10 min
XeF2 þ ð4-C5F4NÞMe3Si
ꢀ!
CH2Cl2
ð4-C5F4NÞIþ XeF2 ꢀ! ð4-C5F4NÞIF2 þ Xe ðcf: ½23ꢃÞ
20 ꢂ
C
no ð4-C5F4NÞXeF or ð4-C5F4NÞ2Xe; mainlyð4-C5F4NÞ2
(4)
CH2Cl2
C6F5IF2 þ C6F5BF2 ꢀ! ½ðC6F5Þ2Iꢃ½BF4ꢃ
20 ꢂC=ꢁ1 min
As a third alternative to establish a Xe–(4-C5F4N) bond we
investigated the fluoride substitution in C6F5XeF [7,10] and
used weakly acidic Cd(4-C5F4N)2 as a transfer reagent of the
heteroaryl group (Eq. (5)).
CH2Cl2
C6F5IF2 þ > 1ð4-C5F4NÞBF2 ꢀ!
0 ꢂC=1 h
½C6F5ð4-C5F4NÞIꢃ½BF4ꢃ þ ½C6F5ð4-C5F4NÞIꢃ
½ð4-C5F4NÞBF3ꢃ
CH2Cl2
2C6F5XeF þ Cdð4-C5F4NÞ2ꢀ78ꢀto!ꢀ50 ꢂC
(9)
2C6F5Xeð4-C5F4NÞ þ CdF2
(5)
Now we append to the former investigation [22] the following
two reactions with less than 1 equiv. of (4-C5F4N)BF2
(Eqs. (10) and (11)).
By this approach the desired pyridylxenon compound
C6F5Xe(4-C5F4N) could be realized. C6F5H, (4-C5F4N)H,
C6F5(4-C5F4N), (C6F5)2, and (4-C5F4N)2 were the character-
istic by-products or decomposition products of the temperature-
sensitive target product. C6F5Xe(4-C5F4N) was characterized
by 19F and 129Xe NMR spectroscopy in CH2Cl2 solution at
ꢀ80 8C. The 19F NMR displayed two signals (ꢀ92.2 and
ꢀ135.0) for the (4-C5F4N) and three signals (ꢀ133.3,
ꢀ153.1, and ꢀ158.6) for the C6F5 group in the correct integral
ratios 2:2 and 2:1:2. The resonances of the C6F5 group appeared
at low frequency in relation to that in [C6F5Xe][AsF6] (MeCN,
32 8C, d ꢀ124.7 (o-F), ꢀ141.4 ( p-F), ꢀ154.4 (m-F) [20]) and
are similar to that in (C6F5)2Xe (CH2Cl2, ꢀ78 8C, d ꢀ133.1 (o-
F), ꢀ154.1 ( p-F), ꢀ159.0 (m-F) [10]). The 129Xe NMR reso-
nance appeared as an unresolved singlet (t1/2 = 112 Hz) at
ꢀ4100 ppm in a comparable position to (C6F5)2Xe (d ꢀ4152
[10]). The constitution of the molecule C6F5Xe(4-C5F4N) was
proved by solvolysis in aHF (Eq. (6)). The cleavage products
[C6F5Xe]+ and (4-C5F4N)H underline that in C6F5Xe(4-C5F4N)
the (4-C5F4N) group possesses a more anionic character than
CH2Cl2
ꢀ!
C6F5IF2 þ < 1ð4-C5F4NÞBF2
½C6F5ð4-C5F4NÞIꢃ½BF4ꢃ
0 ꢂC=spontaneously
(10)
CH2Cl2
ð4-C5F4NÞIF2 þ < 1ð4-C5F4NÞBF2 ꢀ!
0 ꢂC= ꢆ 10 min
½ð4-C5F4NÞ2Iꢃ½BF4ꢃ
(11)
Reaction (11) proceeded slower than (10). The important
information from Eq. (11) is that fluorine-(2,3,5,6-tetra-
fluoropyridyl) substitution took place. Even if the IF2 triad is
bonded to the strong electron-withdrawing (4-C5F4N) group it
reacts with the highly acidic pyridylboron difluoride and forms
the corresponding onium salt. This reactivity is in contrast to
that of XeF2 where [(4-C5F4N)Xe][BF4] is not formed (see
Section 2.1).
It is worth mentioning that in the optimized reaction of
C6F5IF2 with less than 1 equiv. of (4-C5F4N)BF2 only the pure

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A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
[C6F5(4-C5F4N)I][BF4] salt resulted. Thus the presence of the
[(4-C5F4N)BF3]ꢀ anion in Eq. (9) is due to a slow consecutive
reaction of very acidic (4-C5F4N)BF2 under abstraction of
fluoride from [BF4]ꢀ (Eq. (12)). Now we have experimentally
verified reaction (12). By the absence of [(4-C5F4N)BF3]ꢀ in
Eq. (10) we can exclude that the intermediate R(R0)IF reacts
faster with (4-C5F4N)BF2 than with BF3 (Scheme 1).
occurred and C3F7BF2 and C3F8 or C6F13BF2 and C6F14 beside
the olefines XCF CF2 were observed.
PFB or PFP
XeF2 þ trans-XCF¼CFBF2ꢀ50ꢀto!ꢀ40 ꢂC
no formation of½trans-XCF¼CFXeꢃ½BF4ꢃ
(13)
X = CF3, C4F9 [4]; PFB = 1,1,1,3,3-pentafluorobutane, PFP
= 1,1,1,3,3-pentafluoropropane.
CH2Cl2
½RðR0ÞIꢃ½BF4ꢃðsÞ þ ð4-C5F4NÞBF2 ꢀ!
In order to compare the reactivity of XeF2 with that of RfIF2
we investigated the reactions of mono-(o-, m-, p-) and
½RðR0ÞIꢃ½ð4-C5F4NÞBF3ꢃ þ BF3
perfluorinated
phenyliodine
difluorides
with
trans-
R ¼ C6F5; R0 ¼ ð4-C5F4NÞ
(12)
CF3CF CFBF2 (Eqs. (14) and (15)). Qualitatively we compared
the reaction with that of CF2 CFBF2 to study the influence of the
CF3 group (CF3: sI = 0.38, sR = 0.16; F: sI = 0.45, sR = ꢀ0.39
[25]) in trans position to BF2 (Eqs. (16) and (17)).
Table 2 compiles 19F spectroscopic data of (4-C5F4N)IIII com-
pounds in MeCN solution. The step from (4-C5F4N)IF2 to [(4-
C5F4N)2I]+ is associated with a high-frequency shift of F2,6 as
well as F3,5 comparable to that observed for the couple C6F5IF2
and [(C6F5)2I]+. The higher deshielding of the p- and m-F atoms
of the C6F5 group in [C6F5(4-C5F4N)I]+ compared to
[(C6F5)2I]+ is in agreement with the stronger electron-with-
drawing nature of the (4-C5F4N) group. Thus the strong polar-
ization of the p-system of the C6F5 group by IIII is consequently
compensated by F–C back-bonding.
CH2Cl2
o-; m-; p-C6FH4IF2 þ trans-CF3CF¼CFBF2 ꢀꢀ6!0 ꢂC
½o-; m-; p-C6FH4ðtrans-CF3CF¼CFÞIꢃ½BF4ꢃ
(14)
(15)
75ꢀ85% yield
CH2Cl2
C6F5IF2 þ trans-CF3CF¼CFBF2 ꢀꢀ6!0 ꢂC
½C6F5ðtrans-CF3CF¼CFÞIꢃ½BF4ꢃ
92% yield
2.3. The substitution of hypervalently bonded fluorine in
fluoroaryliodine difluorides using perfluoroalk-1-enylboron
difluorides
CH2Cl2
o-; m-; p-C6FH4IF2 þ CF2¼CFBF2 ꢀꢀ6!0 ꢂC
½o-; m-; p-C6FH4ðCF2¼CFÞIꢃ½BF4ꢃ
(16)
(17)
In general, aryl(perfluoroalk-1-enyl)iodonium salts are
promising electrophilic perfluoroalkenylating agents, because
of the high fugality of aryliodides [24]. In addition to the
necessity of developing a widely applicable synthesis there was
theaspecttocomparetheintroductionofperfluoroalkenylgroups
into aryliodine difluorides with that into XeF2. Recently we
introduced a larger variety of fluorinated alk-1-enyl groups into
XeF2 using the corresponding boranes CF2 CXBF2 (X = H, Cl,
CF3) [3] or XCF CFBF2 (X = F, trans-H, cis- and trans-Cl, cis-
CF3, cis-C2F5) [4]. In case that X was a perfluoroalkyl substituent
trans to the BF2 group in XCF CFBF2 the reaction failed
(Eq. (13)) and mainly addition across the C C double bond
79ꢀ94% yield
CH2Cl2
C6F5IF2 þ CF2¼CFBF2 ꢀꢀ6!0 ꢂC ½C6F5ðCF2¼CFÞIꢃ½BF4ꢃ
91% yield
The conversion of RfBF2 in reactions ((14)–(17)) proceeded
quantitatively in less than 30 min at ꢀ60 8C. Different to the
system XeF2/trans-CF3CF CFBF2 where no fluorine substitu-
tion took place below ꢀ40 8C, o-, m-, p-C6FH4IF2 as well as
C6F5IF2 with the strong electron-withdrawing C6F5 group under-
went successful transformations to the corresponding onium
salts.
Table 2
19F NMR shift values d (ppm) of (4-C5F4N)IIII compounds in MeCN
Compounds
T (8C)
MeCN
F2,6
F3,5
IF2
[BF4]ꢀ
(4-C5F4N) moiety
a
(4-C5F4N)IF2
[C6F5(4-C5F4N)I][BF4]b
[(4-C5F4N)2I][BF4]b
24
24
24
ꢀ86.1
ꢀ84.3
ꢀ83.9
ꢀ125.8
ꢀ123.1
ꢀ122.5
ꢀ162.5
ꢀ148.9
ꢀ148.8
Compounds
T (8C)
MeCN
o-F
p-F
m-F
IF2
[BF4]ꢀ
C6F5 moiety
C6F5IF2
24
24
24
ꢀ123.0
ꢀ119.7
ꢀ120.2
ꢀ144.6
ꢀ140.5
ꢀ141.1
ꢀ157.1
ꢀ155.0
ꢀ155.2
ꢀ160.5
[C6F5(4-C5F4N)I][BF4]
[(C6F5)2I][BF4]b
ꢀ148.9
ꢀ149.4
a
In CH2Cl2: ꢀ84.9 ꢀ125.3, ꢀ160.5.
b
Insoluble in CH2Cl2.

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1315
Table 3
The dependence of 19F NMR shift values d (ppm) of [x-C6FH4(XCF CF)I][BF4] salts on the coordination property of the solvent
x-C6FH4(trans-XCF CF)I+ compounds T (8C) MeCN
x-F
CH2Cl2
F1
F2
trans-X [BF4]ꢀ
x-F
F1
F2
trans-X [BF4]ꢀ
[o-C6FH4(FCF CF)I][BF4]
24
24
24
24
24
24
ꢀ95.0
ꢀ158.2 ꢀ98.0
ꢀ78.7
ꢀ78.8
ꢀ79.5
ꢀ148.5 ꢀ94.8
ꢀ157.8 ꢀ98.0
ꢀ79.0
ꢀ79.1
ꢀ79.0
ꢀ143.6
ꢀ143.2
ꢀ143.9
ꢀ141.8
ꢀ142.5
ꢀ142.5
[m-C6FH4(FCF CF)I][BF4]
ꢀ105.0 ꢀ158.5 ꢀ98.2
ꢀ102.7 ꢀ158.9 ꢀ98.7
ꢀ148.7 ꢀ104.3 ꢀ158.1 ꢀ98.6
ꢀ148.3 ꢀ101.7 ꢀ157.9 ꢀ98.9
[p-C6FH4(FCF CF)I][BF4]
[o-C6FH4(trans-CF3CF CF)I][BF4]
[m-C6FH4(trans-CF3CF CF)I][BF4]
[p-C6FH4(trans-CF3CF CF)I][BF4]
ꢀ94.1
ꢀ140.4 ꢀ119.3 ꢀ67.4
ꢀ148.7 ꢀ93.1
ꢀ138.2 ꢀ119.4 ꢀ67.7
ꢀ104.7 ꢀ140.7 ꢀ119.9 ꢀ67.5
ꢀ101.9 ꢀ141.4 ꢀ120.2 ꢀ67.5
ꢀ148.4 ꢀ103.5 ꢀ139.1 ꢀ120.1 ꢀ68.4
ꢀ148.6 ꢀ101.4 ꢀ140.2 ꢀ120.8 ꢀ68.6
CH2Cl2=ꢀ60 ꢂC
All mentioned aryl(1,2,3,3,3-pentafluoroprop-1-enyl)iodo-
nium and -(trifluorovinyl)-iodonium salts are colorless solids
stable at room temperature. In case of the C6F5 species the
thermal stability was determined in closed melting capillaries
and by DSC measurements: [C6F5(trans-CF3CF CF)I][BF4]
160–162 8C (capillary) and 161.2 8C (Tonset, endothermal
process); [C6F5(CF2 CF)I][BF4] 108–110 8C (capillary) and
109.7 8C (Tonset, endothermal process). All [C6FH4(XCF CF)
I][BF4] salts are not only soluble in coordinating solvents
(MeCN, MeNO2) but also in weakly coordinating, polar
solvents (CH2Cl2). This property allows to investigate the effect
of close contact ion pairing. Such an interaction is responsible
for the significant deshielding caused by the change of solvent
from MeCN to CH2Cl2 (Table 3) of the boron-bonded fluorine
atoms (Dd(19F) = 4.4–4.9 ppm for X = F and 5.9–6.9 ppm for
X = trans-CF3). A less expressed deshielding can also be found
for the fluorine atom F1 of the alk-1-enyl group and the single
fluorine atom in the phenyl group. This deshielding is stronger
for X = trans-CF3 than for X = F.
C6F5IF2 þ C6H5PF4
ꢀ!
½C6F5ðC6H5ÞIꢃ½PF6ꢃ
(21)
The temperature at which the fast reactions ((18)–(21)) started
differed and increased parallel to lower acidity in case of
identical RfIF2 molecules (Eqs. (18) versus (19) and (20) versus
(21)). Aryliodine difluorides with electron-withdrawing aryl
groups (low fluoride donors) require in case of the less acidic
aryltransfer reagent C6H5BF2 (Eqs. (20) versus (18)) a higher
starting temperature for the reaction.
The iodonium salts [C6FH4(C6H5)I][AFn+1] (E = B, n = 3;
E = P, n = 5) are soluble in MeCN but also in weakly
coordinating CH2Cl2 and show in comparison to
[C6FH4(XCF CF)I][BF4] salts a significantly lower tendency
to form close contact ion pairs (Table 4). The deshielding of
their [BF4]ꢀ anion in CH2Cl2 is reduced to 2.9–3.4 ppm. We
deduce this to a lower positive partial charge on iodine and
explain this by the ability of the electron-rich phenyl group to
take over positive charge better than perfluoroalkenyl groups.
2.5. Influences on the fluorine–fluoroorgano group
substitution in hypervalent EF2 triads and presentation of
gas phase acidities (fluoride affinities pFꢀ) of organo- and
perfluoroorganoelement fluorides
2.4. A comparison of two reagents of different fluoro acid
types, phenylboron difluoride and phenylphosphorous
tetrafluoride, in aryl transfer reactions forming iodonium
salts
There are four main factors which influence the reaction of
the EF2 triad with Lewis acidic RAFnꢀ1 reagents to the
corresponding onium salts: the acidity of RAFnꢀ1, the
nucleophilicity and nucleofugality of the group R in
RAFnꢀ1, the fluoride donor property of the EF2 triad, and
the electrophilicity of E in EF2. In this paper we want to focus
on the acidity of RAFnꢀ1 and discuss the other three factors on
the basis of the actual results only shortly.
We compared the reaction of p-C6FH4IF2 with C6H5BF2 and
C6H5PF4 (Eqs. (18) and (19)) to show the influence of the type
of fluoro acid and its acidity on the formation of iodonium salts.
Additionally we indicated the influence of distinct fluoride
donor properties of IF2 groups and compared the reaction of p-
C6FH4IF2 and C6F5IF2 with C6H5BF2 (Eqs. (18) and (20)).
Finally we showed the reactivity of C6H5BF2 and C6H5PF4 in
their reactions with C6F5IF2 (Eqs. (20) and (21)). In the here
discussed series, C6F5IF2 is the candidate with the lowest
fluoride donor property and C6H5PF4 the strongest acid.
In arylelement compounds a C6F5 group takes over more
negative partial charge than a C6H5 group. The transition of
RAFnꢀ1 to [RAFn]ꢀ (R = aryl) is associated with a higher
CH2Cl2=ꢀ50 ꢂC
p-C6FH4IF2 þ C6H5BF2
½ p-C6FH4ðC6H5ÞIꢃ½BF4ꢃ
ꢀ!
Table 4
The dependence of 19F NMR shift values d (ppm) of x-C6FH4(C6H5)I[BF4] salts
on the coordination property of the solvent
(18)
CH2Cl2=ꢀ60 ꢂC
x-C6FH4(C6H5)I[BF4]
T (8C)
MeCN
CH2Cl2
p-C6FH4IF2 þ C6H5PF4
½ p-C6FH4ðC6H5ÞIꢃ½PF6ꢃ
ꢀ!
x-F
[BF4]ꢀ
x-F
[BF4]ꢀ
(19)
(20)
o-C6FH4(C6H5)I[BF4]
m-C6FH4(C6H5)I[BF4]
p-C6FH4(C6H5)I[BF4]
24
24
24
ꢀ95.7
ꢀ105.8
ꢀ104.4
ꢀ149.7
ꢀ148.9
ꢀ149.2
ꢀ95.5
ꢀ105.2
ꢀ104.6
ꢀ146.6
ꢀ146.0
ꢀ145.8
CH2Cl2=ꢀ40 ꢂC
C6F5IF2 þ C6H5BF2
ꢀ!
½C6F5ðC6H5ÞIꢃ½BF4ꢃ

1316
A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
nucleofugality for R = C6F5 than for R = C6H5 as demonstrated
for the introduction of aryl groups into IF5 under basic
conditions [26]. If we compare the nucleophilicity of the C6F5
and the (4-C5F4N) group we have to consider that in the (4-
C5F4N) group more negative partial charge is located on
nitrogen than on the ipso carbon. Thus C6F5 can more easily be
introduced into RIF2 than (4-C5F4N). The influence of the
fluoride donor property of the EF2 triad could be proved by
varying R in RIF2. Strong electron-withdrawing groups R
increase the positive partial charge on iodine and make the
Table 5
Fluoride affinities pFꢀ of organodifluoroboranes and related compounds
Lewis acid RAFnꢀ1
pFꢀa
Referenceb
8.31
Difference in acidity RFAFnꢀ1/RHAFnꢀ1
D(pFꢀ)
BF3
7.88
9.98
9.67
9.61
9.58
9.40
9.08
9.00
8.90
8.90
8.51
8.03
7.62
7.53
7.43
7.25
7.16
7.10
6.89
6.87
6.77
6.71
6.59
6.55
6.53
6.46
6.35
6.26
(CF3)3CBF2
CF3CF2CF2BF2
(CF3)2CFBF2
CF3CF2BF2
(CF3)3CBF2/(CH3)3CBF2
3.11
3.08
2.90
3.05
2.94
1.46
2.65
2.64
2.01
1.74
1.48
CF3CF2CF2BF2/CH3CH2CH2BF2
(CF3)2CFBF2/(CH3)2CHBF2
CF3CF2BF2/C2H5BF2
CF3BF2
CF3BF2/CH3BF2
(4-C5F4N)BF2
cis-CF3CF CFBF2
trans-CF3CF CFBF2
CF3CBB CBF2
C6F5BF2
(4-C5F4N)BF2/(4-C5H4N)BF2
cis-CF3CF CFBF2/cis-CH3CH CHBF2
trans-CF3CF CFBF2/trans-CH3CH CHBF2
CF3CBB CBF2/CH3CBB CBF2
C6F5BF2/C6H5BF2
CF2 CFBF2
(4-C5H4N)BF2
FCBB CBF2
CF2 CFBF2/CH2 CHBF2
FCBB CBF2/HCBB CBF2
0.10
HCBB CBF2
m-FC6H4BF2
o-FC6H4BF2
p-FC6H4BF2
CH3CBB CBF2
(CH3)3CBF2
C6H5BF2
(CH3)2CHBF2
CH3CH2CH2BF2
CH2 CHBF2
C2H5BF2
CH3BF2
cis-CH3CH CHBF2
trans-CH3CH CHBF2
SiF4
7.18
8.45
7.98
7.45
6.58
6.24
6.12
6.05
5.76
5.31
4.92
3.95
3.03
2.68
7.35
C2F5SiF3
C2F5SiF3/C2H5SiF3
3.14
1.40
1.69
(4-C5F4N)SiF3
C6F5SiF3
(4-C5F4N)SiF3/(4-C5H4N)SiF3
C6F5SiF3/C6H5SiF3
(4-C5H4N)SiF3
m-FC6H4SiF3
p-FC6H4SiF3
o-FC6H4SiF3
C6H5SiF3
C2H5SiF3
C6F5Si(CH3)3
(CH3)3SiCN
(CH3)3SiF
C6F5Si(CH3)3/C6H5Si(CH3)3
2.24
C6H5Si(CH3)3
PF5
8.92
9.78
9.58
8.81
8.62
8.15
7.47
7.44
7.34
7.30
9.49
(4-C5F4N)PF4
C2F5PF4
(4-C5F4N)PF4/(4-C5H4N)PF4
C2F5PF4/C2H5PF4
0.97
2.11
(4-C5H4N)PF4
C6F5PF4
C6F5PF4/C6H5PF4
0.47
C6H5PF4
C2H5PF4
m-FC6H4PF4
o-FC6H4PF4
p-FC6H4PF4
a
The fluoride affinities pFꢀ were calculated on the B3LYP level using the 6-31 + G* basis set for the isodesmic reaction RAFnꢀ1 + [COF3]ꢀ ! [RAFn] + COF2
and the experimentally known fluoride affinity of COF2 = 49.9 kcal/mol [27].
b
pFꢀ values from Ref. [27].

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1317
polarization and finally the cleavage of the I–F bond by Lewis
acids more difficult. On the other hand electron-withdrawing
groups R in RIF2 increase the electrophilicity of iodine and
favor the interaction with the nucleophile and thereby the
onium cation formation.
by insolubility, and (c) weak interaction under polarization of
one E–F bond, followed by the migration of the nucleophilic
group R to the electrophilic center E.
But it should be pointed out that the transformation of
hypervalent EF2 triads into the corresponding organoonium
cations cannot only be predicted on the basis of the acidity of
the RAFnꢀ1 reagent.
An important parameter which influences the formation of
onium ions from the corresponding EF2 compounds is the acidity
of the Lewis acid RAFnꢀ1 which acts as transfer reagent of the
organo group R. To have a quantitative basis for argumentation
we decided to calculate gas phase acidities (fluoride affinities
pFꢀ) on the B3LYP level using the 6-31+G* basis set. Fluoride
affinities for most common inorganic Lewis acidic fluorides have
been calculated at the correlated MP2/PDZ level of theory by
Christe. [27] The difference in pFꢀ values of BF3, SiF4, and PF5
obtained from B3LYP/6-31+G* calculations shows, compared to
MP2/PDZ calculations (higher level of theory), the same
tendency of deviation in all three Lewis acids which is
minimized in case of the highly symmetric SiF4 molecule
(2.3%), relative to BF3 (5.2%) and PF5 (6.0%).
3. Conclusion
In reactions with XeF2, (4-C5F4N)BF2 behaves differently to
the related fluorophenyldifluoroboranes. Instead of fluorine-(4-
C5F4N) substitution adduct formation proceeded. A Xe-(4-
C5F4N) compound can principally be synthesized but on a
different route using the reaction of C6F5XeF with Cd(4-
C5F4N)2. Generally, the hypervalent IF2 moiety in RIF2 is more
reactive to Lewis acidic transfer reagents than XeF2. Thus (4-
C5F4N)BF2 and trans-CF3CF CFBF2 did not successfully
transfer their organo group into XeF2 but enable the synthesis of
the corresponding iodonium salts [C6F5(4-C5F4N)I][BF4], [(4-
C5F4N)2I][BF4], and [R(trans-CF3CF CF)I][BF4] (R = C6F5,
o-, m-, p-C6FH4). The same approach can be applied to
synthesize [R(R0)I][BF4] salts (R = C6F5, o-, m-, p- C6FH4,
R0 = CF2 CF and C6H5) and can be expanded to reagents of the
RPF4 type. The acidity of RAFnꢀ1 is an important but not the
only factor which determines the result of such fluorine-organyl
substitution reactions. Fluoride affinities of organodifluorobor-
anes and related moderate Lewis acids are helpful tools for
planning the transformation of hypervalent triads EF2 into the
corresponding [RE]+ onium salts.
Table 5 includes the Lewis acids BF3, SiF4, and PF5 and
selected organo derivatives RBF2, RSiX3, RPF4. It is worth to
remember the sequence of gas phase acidity of the inorganic
fluorides considered here: SiF4 < BF3 < PF5. The class (alkyl,
alk-1-enyl, phenyl, heteroaryl, alk-1-ynyl) and the type
(hydrocarbon and perfluorinated one) of the organo group
present in boranes RBF2, which are in the focus of this work,
were varied. In case of the RfBF2 compounds we find both
properties: more and less acidic molecules than BF3 itself. For
RfBF2 with Rf = (CF3)3C, CF3CF2CF2, (CF3)2CF, CF3CF2,
CF3, (4-C5F4N), cis- and trans-CF3CF CF, CF3CBBC, C6F5,
and CF2 CF higher pFꢀ values were calculated than for the
parent molecule BF3, whereas a lower one for FCBBCBF2. The
C6F5 derivatives of SiF4 and PF5 show a different behavior:
C6F5SiF3 is more acidic than SiF4, but C6F5PF4 less acidic than
PF5. As expected, in all cases the perfluorinated organo
difluoroboranes are more acidic than their hydrocarbon
analogs. Caused by their si values [25] the series of acidity
is headed by perfluoro species of the alkyl class followed by the
ones of the pyridyl, alk-1-enyl, alk-1-ynyl and aryl class. In the
right column of Table 5 the increase of acidity caused by
perfluorination of the organo group is displayed. It is worth
mentioning that the influence of perfluorination of the phenyl
group has a significantly stronger implication on acidity in case
of the fluoroborane than of the fluorosilane or fluoro-
phosphorane. The high acidity of (4-C5F4N)BF2 which played
an important role in the distinct reactivity of (4-C5F4N)BF2 and
C6F5BF2 towards XeF2 (see Section 2.1) is supported by the
pFꢀ values in the gas phase. The higher acidity of (4-
C5F4N)BF2 in comparison to that of C6F5BF2 is also in
agreement with the experimental finding that for the abstraction
of fluoride from K[(4-C5F4N)BF3] the strong Lewis acid AsF5
is needed [22] whereas less strong BF3 is sufficient in case of
K[C6F5BF3] [28]. Based on our present knowledge about the
interaction of the EF2 triad with Lewis acids RAFnꢀ1 we can
principally discuss three simplified cases: (a) abstraction of
fluoride and formation of [EF][RAFn] (contact ion pairs or
solvent separated ions), (b) adduct formation, mainly stabilized
4. Experimental details
NMR spectra were recorded on the Bruker spectrometer
AVANCE 300 (1H at 300.13 MHz, 11B at 96.29 MHz, 13C at
75.47 MHz, 19F at 282.40 MHz, and 129Xe at 83.46 MHz). The
chemical shifts are referenced to TMS (1H, 13C), BF3ꢄOEt2/
CDCl3 15% v/v (11B), CCl3F (19F) (C6F6 as a secondary
reference, d = ꢀ162.9), and XeOF4 (XeF2 as a secondary
reference, XeF2/MeCN/297 K (c ! 0), d ꢀ1813.28 ppm [29]).
Low temperature (ꢀ60 8C) Raman spectra were recorded on
the Bruker FT-Raman spektrometer RFS 100/S. DSC measure-
ments were made with a Netzsch 204/1/g Phoenix instrument.
The samples were placed in aluminium pans with a pierced lid
and measured under an atmosphere of dry N2 (heating rate
10 8C/min). Standard quantum chemical calculations were
performed with the GAUSSIAN 03 program package [30]. DFT
calculations were carried out using the B3LYP method with the
basis set 6-31+G* to obtain fluoride affinities pFꢀ. Optimized
geometries were obtained at the RHF/LANL2DZ and RHF/
UGBS level. Standard geometries were used as starting points
for the structure optimizations, which were performed without
any symmetry restrictions.
2,3,5,6-tetrafluoropyridine (4-C5F4N)H and (4-C5F4N)BF2
were synthesized according to Refs. [31,22]. Cd(4-C5F4N)2 was
obtained by decarboxylation of Cd[(4-C5F4N)CO2]2 [32]. Trans-
CF3CF CFBF2 was prepared in four steps from CF3CF CF2 via

1318
A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
trans-CF3CF CFH [33], Li[trans-CF3CF CFB(OMe)3] [34],
and K[trans-CF3CF CFBF3] [34]. CF2 CFBF2 was synthe-
sized according [35], C6H5BF2 was obtained from the reaction of
K[C6H5BF3] with BF3 in CH2Cl2 analog [28]. Cis/trans-
configuration in olefinic products resulting from the correspond-
ing boranes is related to the position of the B-containing
substituent in the parent compound. C6H5PF4 was prepared from
C6H5PF2 and SbF3 [36]. C6F5IF2 was produced by low-
temperature fluorination [37] and x-C6FH4IF2 (x = o-, m-, p-)
by oxygen–fluorine substitution [34].
added slowly in five portions to an intensively stirred XeF2
(33.5 mg, 0.198 mmol) solution in CH2Cl2 (5 ml, ꢀ45 8C).
Within 20 min precipitation proceeded. After 75 min at ꢀ40 8C
the mother liquor was separated, the solid product washed with
CH2Cl2 (2 ꢈ 3 ml, ꢀ40 8C) and dried in vacuum (ꢀ40 8C, 2 h).
The white product suspended in CH2Cl2 at < ꢀ40 8C gave the
same reaction with [NBu4]I as described above. The excess of
XeF2 was proved in the mother liquor.
4.1.2. Reaction of 2,3,5,6-tetrafluoropyridin-4-
yltrimethylsilan with xenon difluoride in the presence of
tetramethylammonium fluoride
4.1. Attempts to prepare 2,3,5,6-tetrafluoropyridin-4-
ylxenon compounds
(4-C5F4N)Si(CH3)3 (678 mg, 3.04 mmol) was added to a
stirred suspension of XeF2 (333 mg, 1.97 mmol) in CH2Cl2
(10 ml, ꢀ60 8C). No reaction took place within 15 min (19F
NMR). After addition of [N(CH3)3]F (51 mg, 0.55 mmol) the
mixture turned black immediately. After 10 min (4-
C5F4N)Si(CH3)3 had been consumed and the 19F NMR
spectrum displayed a mixture (d (ppm); molar ratio) of Me3SiF
(ꢀ158.2, dec, 3J(F, H) = 7 Hz, 1J(F, Si) = 274; 100), (4-
C5F4N)2 (ꢀ87.6, m, 4F, F2,6 ꢀ138.5, m, 4F, F3,5; 67) [38], XeF2
4.1.1. Reaction of 2,3,5,6-tetrafluoropyridin-4-
yldifluoroborane with xenon difluoride in methylene
chloride under formation of the adduct (4-C5F4N)BF2ꢄXeF2
A cold solution (ꢀ36 8C) of XeF2 (40 mg, 0.236 mmol) in
CH2Cl2 (1 ml) was added to a colorless suspension of (4-
C5F4N)BF2 (48 mg, 0.235 mmol) in CH2Cl2 (3.5 ml, ꢀ36 8C).
After 10 min of stirring a green–blue solid was formed beside a
colorless mother liquor which contained only by-products
deriving from attacks on the solvent: CH2ClF, CCl2HF, CH2F2,
(19F NMR, ꢀ40 8C). After 1 h at ꢀ40 8C the suspension was
subdivided into two approximately equal portions. Each was
centrifuged (ꢀ78 8C). The mother liquors were separated and the
solid products were washed with 1 ml CH2Cl2 (ꢀ50 8C) and
dried (HV, 40 min, ꢀ50 8C). Twowhitesolids(AandB)resulted.
Caution: The solid product is shock sensitive. Furthermore
cooled (ꢁꢀ 60 8C) samples in FEP tubes (di = 3.5 mm)
exploded several times during the alignment in the Raman
spectrometer.
1
(ꢀ175.9, s, J(F, Xe) = 5594 Hz; 22), (4-C5F4N)H (ꢀ92.3, m,
2F, F2,6, ꢀ141.0, m, 2F, F3,5; 3) [39], C5F5N (ꢀ87.6, m, 2F, F2,6
,
ꢀ133.2m, 1F, F4, ꢀ162.0 m, 2F, F3,5; 2), and unknown (4-
C5F4N)X compounds; 6). After 20 h at ꢀ40 8C the distribution
of products did not change.
4.1.3. Synthesis of pentafluorophenyl(2,3,5,6-
tetrafluoropyridin-4-yl)xenon
Solid Cd(4-C5F4N)2 (116 mg, 0.28 mmol) was added to
C6F5XeF (125 mg, 0.39 mmol) dissolved in CH2Cl2 (1 ml,
ꢀ78 8C). The mixture was diluted with CH2Cl2 (1 ml, ꢀ78 8C)
and after 10 min at ꢀ78 8C the suspension (gray solid with a
clear mother liquor) was warmed to ꢀ50 8C and stirred for
45 min. After sedimentation of the solid at ꢀ78 8C the mother
liquor was separated. The solid was washed with CH2Cl2
(ꢀ78 8C, 3 ꢈ 0.5 ml). All CH2Cl2-phases were combined and
evaporated to dryness (HV, ꢀ50 8C, 2 h). The white solid
residue was washed with pentane (ꢀ78 8C, 3 ꢈ 1 ml) and dried
(HV, ꢀ50 8C, 1 h). About 62 mg (<0.14 mmol) of C6F5Xe(4-
C5F4N), still contaminated with decomposition products (see
below), were obtained.
Raman spectrum of the adduct in FEP (ꢀ60 8C): 127 (19),
187 (14), 205 (16), 221 (16), 440 (62), 460 (63), 517 (98), 536.1
(24, n(Xe–Fbridging), 548 (12, n(Xe–Fterminal), 593 (55), 638
(54), 679 (11), 704 (16), 749 (100), 908 (22), 1169 (10), 1256
(16), 1427 (19), 1508 (22), 1567 (17), 1674 (16) cmꢀ1
.
Solid A (ꢇ0.1 mmol) was stored at ꢀ78 8C before CH2Cl2
(ꢀ50 8C, 0.5 ml) was added. The suspension turned green–blue.
After addition of a cold [NBu4]I solution (43 mg, 0.117 mmol) in
CH2Cl2 (0.77 ml, ꢀ50 8C) a light orange solution resulted. After
10 min at ꢀ50 8C the temperature was raised to 20 8C. During
warming gas bubbles escaped. When the evolution of gas was
finished a second portion of [NBu4]I was added. No further gas
evolution could be observed. The 19F NMR spectrum of the
solution (ꢀ40 8C) showed the presence of [(4-C5F4N)BF3]ꢀ
(89 mol%), [BF4]ꢀ (9 mol%), and (4-C5F4N)H (2 mol%).
Solid B (ꢇ0.1 mmol) was suspended in cold CH2Cl2 (1 ml,
ꢀ48 8C) and turned green–blue. A solution of [NMe4]F (43 mg,
0.117 mmol) in CH2Cl2 (1 ml, ꢀ40 8C) was added. 19F
monitoring of the suspension at ꢀ40 8C indicated only traces
of non-reacted [NMe4]F beside traces of XeF2. Warming of the
suspension to 20 8C within 18 h showed that XeF2 (11 mol%)
was present beside an unknown (4-C5F4N) product (d ꢀ83.3
and ꢀ123.9, 23 mol%).
C6F5Xe(4-C5F4N): 19F NMR (CH2Cl2, ꢀ80 8C) d ꢀ92.2
(m, 2F, F2,6, (4-C5F4N)), ꢀ133.3 (m, 2F, F2,6, C6F5), ꢀ135.0
(m, 2F, F3,5, (4-C5F4N)), ꢀ153.1 (t, 3J(F4, F3,5) = 21 Hz, 1F, F4,
C6F5), ꢀ158.6 (m, 2F, F3,5
, C6F5), C6F5Xe(4-C5F4N)
64.1 mol%, (4-C5F4N)Cl (ꢀ90.6, m, 2F, F2,6, ꢀ141.4 m, 2F,
F3,5; 16 mol%) [40], (4-C5F4N)H (7 mol%) [39], C6F5(4-
C5F4N) (4 mol%) [38], C6F5H (3 mol%), (C6F5)2 (2 mol%),
C6F6 (2 mol%), (4-C5F4N)2 (1 mol%), 129Xe NMR (CH2Cl2,
ꢀ80 8C) d ꢀ4099.8; t1/2 = 112 Hz).
Solvolysis of C6F5Xe(4-C5F4N) in aHF: In a 3.5 mm i.d.
FEP trap C6F5Xe(4-C5F4N) (28.3 mg, < 0.063 mmol) was
cooled to ꢀ78 8C before cold aHF (0.4 ml, ꢀ78 8C) was added.
After 1 h at ꢀ78 8C the 19F NMR spectrum (ꢀ80 8C) confirmed
the conversion of C6F5Xe(4-C5F4N) under formation of
[C6F5Xe]+ (ꢀ123.6, m, 2F, F2,6, ꢀ138.3, m, 2F, F4, ꢀ151.7,
In an alternative procedure a cold solution of (4-C5F4N)BF2
(31.6 mg, 0.159 mmol) in CH2Cl2 (13,3 ml, ꢀ30 8C) was

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1319
m, 2F, F3,5) and (4-C5F4N)H in the molar ratio 1.0:0.9. The
and dried in vacuum. [C6F5(4-C5F4N)I][BF4] was yielded
quantitatively.
129Xe NMR (ꢀ80 8C) corroborated the presence of [C6F5Xe]+ d
3
ꢀ3917.6 (t, J(Xe, F) = 61 Hz) [20].
19F NMR (24 8C, CH3CN) d ꢀ84.3 (m, 2F, F2,6, (4-C5F4N)),
ꢀ119.7 (m, 2F, F2,6, C6F5), ꢀ123.1 (m, 2F, F3,5, (4-C5F4N)),
ꢀ140.5 (tt, 3J(F4, F3,5) = 20 Hz, 4J(F4, F2,6) = 7 Hz, F4, C6F5),
ꢀ155.0 (m, 1F, F3,5, C6F5), ꢀ148.8/ꢀ148.9 (s, 4F, [10BF4]ꢀ/
[11BF4]ꢀ).
4.2. Preparation of 2,3,5,6-tetrafluoropyridin-4-yliodine
compounds
4.2.1. 2,3,5,6-tetrafluoropyridin-4-yliodine (4-C5F4N)I as
starting material
4.2.4. Reaction of pentafluorophenyl(2,3,5,6-
tetrafluoropyridyl)iodonium tetrafluoroborate with (2,3,5,6-
tetrafluoropyridyl)difluoroborane
Within 2.5 h a n-BuLi solution (80.15 mmol in 32 ml hexane)
was added under intensive stirring to a ꢀ78 8C cold solution of
2,3,5,6-tetrafluoropyridine (11.532 g, 76.34 mmol) in diethy-
lether (40 ml). The suspension was stirred for 1 h at ꢀ78 8C
before a solution of ICl (13.01 g, 80.15 mmol) in diethylether
(40 ml) was added within 30 min. The crimson solution was
warmed to ꢀ40 8C and stirred for 2 h before HClaq (10%, 50 ml)
was added. The crimson ether phase was separated and treated
with a saturated aqueous solution (50 ml) of Na2SO3 till
discoloration. Theaqueousphasewasextractedwithdiethylether
(2 ꢈ 25 ml). The combined ether phases were dried over
MgSO4. Ether was distilled and the residue treated at 0 8C
and 23 h Pa for 10 min till a brown solid resulted which was
dissolved in diethylether (10 ml) and evaporated at 20 8C and
23 h Pa. The purification was repeated and the nearly colorless
solid was finally sublimed (ꢁ48 8C, 23 hPa). Transparent square
shaped prisms were obtained. 19F NMR(CH3CN, 24 8C) d ꢀ91.3
(m, 1J(F, C) ꢅ248 Hz, 2F, F2,6) ꢀ123.6 (m, 1J(F, C) = 253 Hz,
2F, F3,5), 19F NMR (CH2Cl2, 24 8C) d ꢀ90.7 (m, 2F, F2,6, ꢀ123.7
m, 2F, F3,5), 13C{1H} NMR (CH3CN, 24 8C) d 144.8 (dm, 1J(C,
F) = 253 Hz, C3,5), 143.5(dm, 1J(C, F) = 245 Hz, C2,6);114.2(tt,
2J(C, F) = 26 Hz, 3J(C, F) = 2 Hz, C4) [41]
A cold solution of (4-C5F4N)BF2 (67 mg, 34 mmol) in
CH2Cl2 (1 ml, 0 8C) was added to a suspension of [C6F5(4-
C5F4N)I][BF4] (216 mg, 0.42 mmol) in CH2Cl2 (1 ml). The
suspension was vigorously stirred in a closed FEP trap. After
5 min the temperature was raised to 20 8C and stirring was
continued for 1.5 h. Fuming of BF3 was observed when a first
sample for 19F NMR monitoring was taken. A second sample
was taken after 18 h (fuming of BF3) before the mother liquor
was separated. Subsequently, the solid residue was washed and
dried in vacuum. The white powder (235 mg) was dissolved in
MeCN (0.7 ml) and its composition was determined by 19F
NMR.
19F NMR (CH3CN, 0 8C) d ꢀ85.1 (m, 2F, F2,6, [(4-
C5F4N)RI]+), ꢀ123.7 (m, 2F, F3,5, [(4-C5F4N)RI]+), ꢀ120.4
(m, 2F, F2,6, [C6F5(R0)I]+), ꢀ141.2 (t, 1F, F4, [C6F5(R0)I]+),
ꢀ155.7 (m, 2F, F3,5, [C6F5(R0)I]+), ꢀ149.2 (br, 4F, [BF4]ꢀ),
ꢀ97.3 (m, 2F, F2,6, [(4-C5F4N)BF3]ꢀ), ꢀ137.7 (m, 2F, F3,5, [(4-
C5F4N)BF3]ꢀ), ꢀ134.1 (br, 3F, [(4-C5F4N)BF3]ꢀ), molar ratio
[C6F5(4-C5F4N)I]+:[BF4]ꢀ:[(4-C5F4N)BF3]ꢀ = 1:0.63:0.41.
[C6F5(4-C5F4N)I][BF4] 129 mg, 0.243 mmol, 58% yield, [C6F5
(4-C5F4N)I][(4-C5F4N)BF3] 105 mg, 0.159 mmol, 38% yield.
19F NMR (CH2Cl2 mother liquor after 1.5 h, 24 8C) d ꢀ81.7
(m, 2F, F2,6, [(4-C5F4N)RI]+), ꢀ122.1 (m, 2F, F3,5, [(4-
C5F4N)RI]+), ꢀ118.1 (m, 2F, F2,6, [C6F5(R0)I]+), ꢀ136.2 (t,
4.2.2. 2,3,5,6-tetrafluoropyridin-4-yliodine difluoride (4-
C5F4N)IF2
XeF2 (1.208 g, 7.13 mmol) was added to (4-C5F4N)I
(1.885 g, 6.81 mmol) which was suspended in CH2Cl2
(20 ml) at ꢀ78 8C. The temperature was raised to ca. 20 8C
and after 4 h a solution resulted. Within 20 h transparent
crystals were formed. The mother liquor was separated and
checked by 19F NMR (CH2Cl2, 24 8C) d ꢀ84.9 (m, 2F, F2,6
ꢀ125.3, m, 2F, F3,5, ꢀ160.5, s, 2F, IF2). It still contained (4-
C5F4N)IF2, (4-C5F4N)I, and XeF2 in the molar ratio 69:21:10.
The crystals were washed (CH2Cl2, 1 ml) and dried in vacuum
and yielded 1.802 g (84%) (4-C5F4N)IF2. 19F NMR (CH3CN,
24 8C) d ꢀ86.1 (m, 2F, F2,6), ꢀ125.8 (m, 2F, F3,5), ꢀ162.5 (s,
3J(F4, F3,5) = 20 Hz, 1F, F4, [C6F5(R0)I]+), ꢀ153.0 (m, 2F, F3,5
,
[C6F5(R0)I]+), ꢀ92.6 (br, 2F, F2,6, [((4-C5F4N)BF2)nF]ꢀ),
ꢀ134.6 (br, 2F, F3,5, [((4-C5F4N)BF2)nF]ꢀ), ꢀ96.3 (br, [((4-
C5F4N)BF2)nF]ꢀ), molar ratio of (4-C5F4N) groups cation:
anion = 1:2.6.
19F NMR (CH2Cl2 mother liquor after 18 h, 24 8C) d ꢀ81.4
(m, 2F, F2,6, [(4-C5F4N)RI]+), ꢀ122.7 (m, 2F, F3,5, [(4-
C5F4N)RI]+), ꢀ117.8 (m, 2F, F2,6, [C6F5(R0)I]+), ꢀ136.0 (t,
3J(F4, F3,5) = 20 Hz, 1F, F4, [C6F5(R0)I]+), ꢀ153.0 (m, 2F, F3,5
,
[C6F5(R0)I]+), ꢀ95.5 (br, 2F, F2,6, [((4-C5F4N)BF2)nF]ꢀ),
ꢀ139.4 (br, 2F, F3,5, [((4-C5F4N)BF2)nF]ꢀ), ꢀ122.9 (br, [((4-
C5F4N)BF2)nF]ꢀ), molar ratio of (4-C5F4N) groups
cation:anion ꢅ 1:1, content of [C6F5(4-C5F4N)I][(4-C5F4N)
BF3] (determined by the internal quantitative standard
C6H5CF3) 0.01 mmol, 3%.
1
2F, IF2) 13C{1H} NMR (CH3CN, 24 8C) d 144.0 (dm, J(C,
1
F) = 235 Hz, C2,6), 140.8 (dm, J(C, F) = 264 Hz, C3,5), 118.9
2
(t, J(C, F) = 24 Hz, C4).
4.2.3. Pentafluorophenyl(2,3,5,6-
tetrafluoropyridyliodonium tetrafluoroborate) [C6F5(4-
C5F4N)I][BF4]
4.2.5. Synthesis of bis(2,3,5,6-tetrafluoropyridin-4-
yl)iodonium tetrafluoroborate [(4-C5F4N)2I][BF4]
A cold solution of (4-C5F4N)BF2 (26 mg, 0.131 mmol) in
CH2Cl2 (6 ml, 0 8C) was added within 30 min to a cold solution
of C6F5IF2 (65 mg, 0.196 mmol). Immediately a slightly yellow
precipitate was formed. After 20 h at 0 8C the mother liquor was
separated and the solid product was washed (2 ꢈ 4 ml CH2Cl2)
Over a period of 30 min a cold solution of (4-C5F4N)BF2
(105.8 mg, 0.53 mmol) in CH2Cl2 (15 ml, 0 8C) was added in
five portions to a stirred solution of (4-C5F4N)IF2 (244 mg,
0.78 mmol) in CH2Cl2 (5 ml, 0 8C) in a 23 mm i.d. FEP trap.

1320
A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
After 10 min a white tarnish appeared. 19F NMR monitoring
F3) = 277 Hz, 2J(C3, F2) = 36 Hz, 3J(C3, F1) = 5 Hz, C3,
alkenyl), 84.6 (tm, 2J(C1, F2,6) = 26 Hz, C1, C6F5).
proceeded after 90 min at 0 8C. The content of the mother liquor
((4-C5F4N)IF2 (59.0 mg, 0.19 mmol)and(4-C5F4N)I(0.016 mg,
0.057 mmol)) was determined using the quantitative internal
standard benzotrifluoride. Following the temperature was raised
to 20 8C and kept for 1.5 h. The suspension was centrifuged, the
mother liquor separated, and the solid residuewashed three times
with CH2Cl2 (3, 2, and finally 1 ml). The yield after drying (HV,
20 8C, 45 min) was 240 mg (0.47 mmol, 88%).
4.3.2. Pentafluorophenyl(trifluorovinyl)iodonium
tetrafluoroborate
The preparation proceeded analog to that of [C6F5(trans-
CF3CF CF)I][BF4] starting from pentafluoro(difluoroiodo)-
benzene (664 mg, 2.00 mmol) in CH2Cl2 (10 ml) at ꢀ60 8C and
trifluorovinylborane CF2 CFBF2 (1.82 mmol) as CH2Cl2
solution (20 ml; ꢀ78 8C). Yield of [C6F5(CF2 CF)I][BF4]
760 mg (1.65 mmol, 91%), melting point (sealed capillary)
108–110 8C, DSC: Tonset 109.7 8C (endothermal process).
[C6F5(CF2 CF)I][BF4] 19F NMR (CH3CN, 24 8C) d ꢀ77.2
(dd, 1F, 3J(F2(trans), F1) = 61 Hz, 2J(F2(trans), F2(cis)) = 27 Hz,
F2(trans), alkenyl), ꢀ95.7 (ddt, 1F, 3J(F2(cis), F1) = 125 Hz,
19F NMR (CH3CN, 24 8C) d ꢀ83.9 (m, 2F, F2,6) ꢀ122.5 (m,
2F, F3,5), ꢀ148.8 (s, 4F, [BF4]ꢀ), minor impurities: (4-
C5F4N)IF2 (0.8 mol%), (4-C5F4N)I (1.1 mol%), [AsF6]ꢀ
(1.7 mol%); 13C{1H} NMR (CH3CN, 24 8C) d 144.3 (dm,
1
1J(C, F) = 250 Hz, C2,6), 142.7 (dm, J(C, F) = 267 Hz, C3,5),
2
106.8 (t, J(C, F) = 25 Hz, C4).
6
2J(F2(cis), F2(trans)) = 27 Hz, J(F2(cis), F2,6) = 5 Hz, F2(cis), alke-
4.3. Preparation of pentafluorophenyl(trans-1,2,3,3,3-
pentafluoroprop-1-enyl)- and
nyl), ꢀ120.5 (m, 2F, F2,6, C6F5), ꢀ140.9 (tt, 1F, 3J(F4,
4
F3,5) = 20 Hz, J(F4, F2,6) = 7 Hz, F4, C6F5), ꢀ148.1 (s, t1/2
pentafluorophenyl(trifluorovinyl)iodonium
tetrafluoroborate
= 4 Hz, 4F, BF4), ꢀ155.3 (m, 2F, F3,5, C6F5), ꢀ157.0 (ddt, 1F,
3J(F1, F2(cis)) = 125 Hz, 3J(F1, F2(trans)) = 61 Hz, 5J(F1,
F2,6) = 3 Hz, F1, alkenyl); 19F NMR (CH2Cl2, 24 8C) d ꢀ75.3
(dd, 1F, 3J(F2(trans), F1) = 63 Hz, 2J(F2(trans), F2(cis)) = 17 Hz,
F2(trans), alkenyl), ꢀ94.9 (ddt, 1F, 3J(F2(cis), F1) = 127 Hz,
4.3.1. Pentafluorophenyl(trans-1,2,3,3,3-pentafluoroprop-
1-enyl)iodonium tetrafluoroborate
6
A solution of trans-1,2,3,3,3-pentafluoroprop-1-enyldifluor-
oborane (2.44 mmol) in CH2Cl2 (20 ml; ꢀ78 8C) was added in
eight equal portions over a period of 0.5 h to the cold stirred
solution of C6F5IF2 (863 mg, 2.60 mmol) in CH2Cl2 (10 ml,
ꢀ60 8C) in a 23 mm i.d. FEP trap. The resulting suspension was
stirred for further 0.5 h at ꢀ50 8C and then warmed to 20 8C
within 1 h. The mother liquor was separated and the white solid
residue washed with CH2Cl2 (4 ꢈ 10 ml) to remove the slight
excess of C6F5IF2. After drying in HV at 20 8C the iodonium
salt was stored in a FEP vessel under an atmosphere of dry
argon at 20 8C. Yield of [C6F5(trans-CF3CF CF)I][BF4] 1.1 g
(2.25 mmol, 92%), melting point (sealed capillary) 160–
162 8C, DSC: Tonset 161.2 8C (endothermal process).
2J(F2(cis), F2(trans)) = 17 Hz, J(F2(cis), F2,6) = 4 Hz, F2(cis), alke-
nyl), ꢀ119.5 (m, 2F, F2,6, C6F5), ꢀ137.8 (tt, 1F, 3J(F4,
4
F3,5) = 21 Hz, J(F4, F2,6) = 7 Hz, F4, C6F5), ꢀ142.0 (s, t1/2
= 4 Hz, 4F, BF4), ꢀ153.8 (m, 2F, F3,5, C6F5), ꢀ156.5 (ddt, 1F,
3J(F1, F2(cis)) = 127 Hz, 3J(F1, F2(trans)) = 63 Hz, 5J(F1,
F2,6) = 3 Hz, F1, alkenyl); 11B NMR (CH3CN, 24 8C); d ꢀ1.4
(s, t1/2 = 2 Hz, BF4); 11B NMR (CD3NO2, 24 8C) d ꢀ1.4 (s, t1/2
= 5 Hz, BF4); 13C NMR (CD3NO2, 24 8C) d 156.3 (ddd, 1J(C2,
1
2
F2(cis)) = 313 Hz, J(C2, F2(trans)) = 290 Hz, J(C2, F1 = 31 Hz,
C2, alkenyl), 147.4 (dm, J(C4, F4) = 263 Hz, C4, C6F5), 147.3
1
(dm, 1J(C2, F2) = 258 Hz, C2,6, C6F5), 138.5 (dm, 1J(C3,
F3,5) = 257 Hz, C3,5, C6F5), 103.2 (ddd, J(C1, F1) = 327 Hz,
1
2J(C1, F2(trans)) = 64 Hz, J(C1, F2(cis)) = 31 Hz, C1, alkenyl),
2
[C6F5(trans-CF3CF CF)I][BF4] 19F NMR (CD3CN, 24 8C)
85.8 (tm, 2J(C1, F2,6) = 26 Hz, C1, C6F5).
3
4
d ꢀ67.4 (dd, 3F, J(F3, F2) = 19 Hz, J(F3, F1) = 10 Hz, F3,
alkenyl), ꢀ117.8 (dqt, 1F, 3J(F2, F1) = 139 Hz, 3J(F2,
4.3.3. The preparation of monofluorophenyl(trans-1,2,3,3,3-
pentafluoroprop-1-enyl)iodonium and monofluorophenyl
(perfluorovinyl)iodonium tetrafluoroborates, [o-, m-, and p-
C6H4F(trans-CF3CF CF)I][BF4] and [o-, m-, and p-
F3) = 19 Hz, J(F2, F2,6) = 4 Hz, F2, alkenyl), ꢀ119.6 (m, 2F,
6
F2,6, C6F5), ꢀ138.2 (dqt, 1F, 3J(F1, F2) = 139 Hz, 4J(F1,
F3) = 10 Hz, J(F1, F2,6) = 5 Hz, F1, alkenyl), ꢀ140.0 (tt, 1F,
5
3J(F4, F3,5) = 20 Hz, 4J(F4, F2,6) = 7 Hz, F4, C6F5), ꢀ147.9.0 (s,
4F, BF4), ꢀ154.9(m, 2F, F3,5, C6F5);19F NMR(CD3NO2, 24 8C)
C6H4F(CF2 CF)I][BF4], general procedure
Monofluoro(difluoroiodo)benzenes (3–4 mmol) were dis-
solved in CH2Cl2 (approximately 12–15 ml) at ꢀ60 8C in a
23 mm i.d. FEP trap provided with a suitable stirring bar. Under
intensive stirring the appropriate quantity (93–98%) of trans-
1,2,3,3,3-pentafluoroprop-1-enylborane, trans-CF3CF CFBF2,
or perfluorovinyldifluorborane, CF2 CFBF2, was added as
CH2Cl2 solution (conc. approximately 0.20 mmol/ml, ꢀ78 8C)
in 8–10 equal portions over a period of 30 min. The resulting
suspension was stirred for further 0.5 h. The mother liquor was
separated from the light yellowish solid. The solid was washed
with CH2Cl2 (2 ꢈ 5 ml) at ꢀ50 8C to remove the slight excess of
monofluorodifluoroiodobenzenes. The salt was dried at ꢆ
ꢀ78 8C in high vacuum. The mother liquor and the CH2Cl2
washing solutions were combined, evaporated (HV, ꢆ ꢀ78 8C),
3
4
d ꢀ66.9 (dd, 3F, J(F3, F2) = 19 Hz, J(F3, F1) = 10 Hz, F3,
alkenyl), ꢀ117.6 (dqt, 1F, 3J(F2, F1) = 139 Hz, 3J(F2,
F3) = 19 Hz, J(F2, F2,6) = 4 Hz, F2, alkenyl), ꢀ119.3 (m, 2F,
6
F2,6, C6F5), ꢀ138.2 (dqt, 1F, 3J(F1, F2) = 139 Hz, 4J(F1,
F3) = 10 Hz, J(F1, F2,6) = 5 Hz, F1, alkenyl), ꢀ139.8 (tt, 1F,
5
3J(F4, F3,5) = 20 Hz, 4J(F4, F2,6) = 7 Hz, F4, C6F5), ꢀ147.4(s, 4F,
BF4), ꢀ154.6 (m, 2F, F3,5, C6F5); 11B NMR (CD3CN, 24 8C) d
ꢀ1.4 (s, BF4); 13C NMR (CD3NO2, 24 8C) d 147.8 (dm, 1J(C4,
F4) = 264 Hz, C4, C6F5), 147.6(dm, 1J(C2,6, F2,6) = 256 Hz, C2,6
,
C6F5), 145.1 (dqd, 1J(C2, F2) = 268 Hz, 2J(C2, F3) = 44 Hz,
2J(C2, F1) = 30 Hz, C2, alkenyl), 138.6 (dm, 1J(C3,5
,
F3,5) = 257 Hz, C3,5, C6F5), 127.5 (ddm, J(C1, F1) = 354 Hz,
1
2J(C1, F2) = 63 Hz, C1, alkenyl), 116.2 (qdd, 1J(C3,

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1321
and the solid residue was washed with n-pentane (3 ꢈ 5 ml) to
p-Fluorophenyl(trans-1,2,3,3,3-pentafluoroprop-1-enyl)io-
remove non-reacted monofluoro(difluoroiodo)benzenes. The
donium tetrafluoroborate prepared from 796.55 mg
(3.063 mmol) p-C6H4FIF2 and 532 mg (2.96 mmol) trans-
CF3CF CFBF2 in 15 ml CH2Cl2; yield 500 mg (1.14 mmol,
38.5%) isolated from the primary precipitation and 602 mg
(1.37 mmol, 46.3%) from the mother liquor; overall yield
1102 mg (2.51 mmol, 84.8%).
1
reaction products were characterized by 19F, 13C, H, and 11B
spectroscopy. The salts can be stored over months under dry
argon at ꢀ70 8C.
o-Fuorophenyl(trans-1,2,3,3,3-pentafluoroprop-1-enyl)io-
donium tetrafluoroborate prepared from 453.4 mg (1.74 mmol)
o-C6H4FIF2 and 309.6 mg (1.72 mmol) trans-CF3CF CFBF2
in 15 ml CH2Cl2; yield 527 mg (1.2 mmol) isolated from the
primary precipitation and 50 mg (0.11 mmol, 6.4%) from the
mother liquor; overall yield 577 mg (1.31 mmol, 76%).
[o-C6H4F(trans-CF3CF CF)I][BF4] 19F NMR (CH2Cl2,
[p-C6H4F(trans-CF3CF CF)I][BF4] 19F NMR (CH2Cl2,
24 8C) d ꢀ68.6 (dd, 3F, 3J(F3, F2) = 19 Hz, 4J(F3, F1) = 11 Hz,
F3, alkenyl), ꢀ101.4 (tt, 1F, 3J(F, H5,3) = 8 Hz, 4J(F,
3
H2,6) = 4 Hz, p-C6H4F), ꢀ120.8 (dq, 1F, J(F2, F1) = 142 Hz,
3J(F2, F3) = 19 Hz, F2, alkenyl), ꢀ140.2 (dq, 1F, 3J(F1,
4
ꢀ40 8C)
d
ꢀ67.7 (dd, 3F, 3J(F3, F2) = 19 Hz, 4J(F3,
F2) = 142 Hz, J(F1, F3) = 11 Hz, F1, alkenyl), ꢀ142.5 (s, 4F,
3
F1) = 11 Hz, F3, alkenyl), ꢀ93.1 (dtdd, 1F, J(F, H3) = 10 Hz,
BF4); 1H NMR (CH2Cl2, 24 8C) d 8.4 (dd, 2H, 3J(H2,
H3) = 9 Hz, 4J(H2, F) = 5 Hz, H2,6), 7.5 (dd, 2H, 3J(H3,
H2) = 9 Hz, 3J(H2, F) = 8 Hz, H3,5); 11B NMR (CH2Cl2,
24 8C) d ꢀ2.2 (s, BF4); 13C{1H} NMR (CH2Cl2, 24 8C) d
4J(F, H4) = 9 Hz, J(F, F1) = 5 Hz, J(F, F2) = 5 Hz, o-C6H4F),
ꢀ119.4 (dqd, 1F, 3J(F2, F1) = 141 Hz, 3J(F2, F3) = 19 Hz, 6J(F2,
F2,6) = 4 Hz, F2, alkenyl), ꢀ138.2 (dqd, 1F, 3J(F1, F2) = 141 Hz,
4J(F1, F3) = 11 Hz, 5J(F1, F2,6) = 6 Hz, F1, alkenyl), ꢀ141.8 (s,
4F, BF4); 1H NMR (CH2Cl2, 24 8C) d 8.4 (ddd, 3J(H6,
H5) = 8 Hz, 4J(H6, F) = 6 Hz, 6J(H6, H4) = 2 Hz, H6), 8.0
5
6
1
1
166.3 (d, J(C4, F4) = 259 Hz, C4, aryl), 144.2 (dqd, J(C2,
F2) = 266 Hz, 2J(C2, F3) = 43 Hz, 2J(C2, F1) = 31 Hz, C2,
alkenyl), 139.9 (d, 3J(C2,6, F) = 10 Hz, C2,6), 125.0 (ddq,
3
3
4
2
3
(ddd, J(H3, F) = 9 Hz, J(H3, H4) = 7 Hz, J(H3, H5) = 2 Hz,
1J(C1, F1) = 350 Hz, J(C1,F2) = 63 Hz, J(C1, F3) = 3 Hz, C1,
H3), 7.7 (ddd, J(H5, H6) = 8 Hz, 3J(H5, H4) = 8 Hz, 4J(H5,
alkenyl), 121.0 (d, 2J(C3,5, F) = 23.4, C3,5), 116.0 (qdd, J(C3,
3
1
H3) = 1 Hz, H5), 7.6 (ddd, 3J(H4, H3) = 8 Hz, 3J(H4, H5) = 8 Hz,
4J(H4, H6) = 1 Hz, H4); 11B NMR (CH2Cl2, 24 8C) d ꢀ1.3 (s,
BF4); 13C{1H} NMR (CH2Cl2, 24 8C) d 160.8 (d, 1J(C2,
F2) = 257 Hz, C2, aryl), 145.2 (ddq, 1J(C2, F2) = 267 Hz, 2J(C2,
F3) = 277 Hz, 2J(C3, F2) = 36 Hz, 3J(C3, F1) = 5 Hz, C3), 104.4
(s, C1).
o-Fluorophenyl(perfluorovinyl)iodonium tetrafluoroborate
prepared from 1000 mg (3.85 mmol) o-C6H4FIF2 and
480 mg (3.69 mmol) CF2 CFBF2 in 15 ml CH2Cl2; yield
745 mg (1.91 mmol, 51.8%) isolated from the primary
precipitate and 496 mg (1.27 mmol, 34.4%) from the mother
liquor; overall yield 1241 mg (3.18 mmol, 86.2%).
[o-C6H4F(CF2 CF)I][BF4] 19F NMR (CH2Cl2, 24 8C) d
2
3
F1) = 44 Hz, J(C2, F3) = 31 Hz, C2, alkenyl), 138.8 (d, J(C4,
F) = 8 Hz, C4), 138.4 (s, C5), 129.3 (d, J(C6, F) = 3 Hz, C6),
3
125.4 (ddq, 1J(C1, F1) = 351 Hz, 2J(C1, F2) = 62 Hz, 3J(C1,
F3) = 3 Hz, C1, alkenyl), 118.7 (d, 2J(C3, F) = 21 Hz, C3), 116.5
(qdd, 1J(C3, F3) = 277 Hz, 2J(C3, F2) = 36 Hz, 3J(C3, F1) = 5 Hz,
C3, alkenyl), 98.1 (d, 2J(C1, F) = 23 Hz, C1).
ꢀ79.0 (dd, 1F, 3J(F2(trans)
,
F1) = 61 Hz, 2J(F2(trans)
,
m-Fluorophenyl(trans-1,2,3,3,3-pentafluoroprop-1-enyl)io-
donium tetrafluoroborate prepared from 824 mg (3.17 mmol)
m-C6H4FIF2 and 606 mg (3.37 mmol) trans-CF3CF CFBF2 in
15 ml CH2Cl2; yield 672 mg (1.53 mmol, 45.4%) isolated from
the primary precipitation and 374 mg (0.85 mmol, 25.2%) from
the mother liquor; overall yield 1046 mg (2.37 mmol, 70.6%).
[m-C6H4F(trans-CF3CF CF)I][BF4] 19F NMR (CH2Cl2,
24 8C) d ꢀ68.4 (dd, 3F, 3J(F3, F2) = 19 Hz, 4J(F3, F1) = 11 Hz,
F3, alkenyl), ꢀ103.5 (ddd, 1F, 3J(F, H2,4) = 8 Hz, 4J(F,
F2(cis)) = 25 Hz, F2(trans)), ꢀ94.8 (m, 1F, o-C6H4F), ꢀ98.0
3
2
(ddd, 1F, J(F2(cis), F1) = 127 Hz, J(F2(cis), F2(trans)) = 25 Hz,
6J(F2(cis), F2)) = 6 Hz, F2(cis)), ꢀ143.6 (s, 4F, BF4) ꢀ157.8
(ddd, 1F, 3J(F1, F2(cis)) = 127 Hz, 3J(F1, F2(trans)) = 61 Hz,
1
5J(F1,F2) = 4 Hz, F1); H NMR (CH2Cl2, 24 8C) d 8.3 (dd,
1H, 3J(H3, F) = 7 Hz, 3J(H3, H4) = 7 Hz, 1H, H3), 7.9 (dd, 1H,
3
3
4J(H6, F) = 7 Hz, J(H6, H5) = 7 Hz, H6), 7.6 (dd, 1H, J(H4,
H5) = 8 Hz, 3J(H4, H3) = 8 Hz, H4); 11B NMR (CH2Cl2, 24 8C)
d ꢀ2.3 (s, BF4); 13C{1H} NMR (CH2Cl2, 24 8C) d 160.1 (d,
1J(C2, F2) = 256 Hz, C2, aryl), 155.3 (ddd, 1J(C2, F2(cis)) = 312,
1J(C2, F2(trans)) = 290 Hz, 2J(C2, F1) = 32 Hz, C2, alkenyl),
3
H5) = 7 Hz, m-C6H4F), ꢀ120.1 (dq, 1F, J(F2, F1) = 142 Hz,
3J(F2, F3) = 19 Hz, F2, alkenyl), ꢀ139.1 (dq, 1F, 3J(F1,
4
3
3
F2) = 142 Hz, J(F1, F3) = 11 Hz, F1, alkenyl), ꢀ142.5 (s, 4F,
137.8 (d, J(C4, F) = 8 Hz, C4), 137.9 (s, C5), 128.4 (d, J(C6,
BF4); 1H NMR (CH2Cl2, 24 8C) d 8.2 (d, 3J(H2, F) = 9 Hz, H2),
F) = 3 Hz, C6), 117.9 (d, J(C3, F) = 21 Hz, C3), 100.5 (ddd,
2
3
3
8.1 (d, J(H6, H5) = 8 Hz, H6), 7.9 (ddd, J(H5, H6) = 8 Hz,
3J(H5, H4) = 8 Hz, 4J(H5, F) = 6 Hz, H5), 7.7 (ddd, 3J(H4,
H5) = 8 Hz, 3J(H4, F) = 8 Hz, 4J(H4, H6) = 2 Hz, H4); 11B NMR
(CH2Cl2, 24 8C) d ꢀ2.1 (s, BF4); 13C{1H} NMR (CH2Cl2,
1J(C1, F1) = 325 Hz,
2J(C1, F2(trans)) = 63.3,
2J(C1,
F2(cis)) = 30 Hz, C1, alkenyl), 98.7 (d, J(C1, F) = 23 Hz, C1).
m-Fluorophenyl(perfluorovinyl)iodonium tetrafluoroborate
prepared from 1040.3 mg (4.00 mmol) m-C6H4FIF2 and
486.2 mg (3.74 mmol) CF2 CFBF2 in 15 ml CH2Cl2; yield
650 mg (1.66 mmol, 44.9%) isolated from the primary
precipitate and 496 mg (1.27 mmol, 34%) from the mother
liquor; overall yield 1146 mg (2.93 mmol, 78.9%).
2
24 8C) d 163.6 (d, J(C3, F3) = 259 Hz, C3, aryl), 144.9 (ddq,
1
1J(C2, F2) = 267 Hz, J(C2, F3) = 44 Hz, J(C2, F1) = 30 Hz,
2
2
C2, alkenyl), 134.9 (d, J(C5, F) = 8 Hz, C5), 133.3 (d, J(C6,
3
4
F) = 4 Hz, C6), 125.5 (ddq, 1J(C1, F1) = 352 Hz, 2J(C1,
F2) = 62 Hz, J(C1, F3) = 3 Hz, C1, alkenyl), 124.7 (d, J(C2,
[m-C6H4F(CF2 CF)I][BF4] 19F NMR (CH2Cl2, 24 8C) d
3
2
F) = 26 Hz, C2), 122.8 (d, J(C4, F) = 21 Hz, C4), 116.4 (ddd,
ꢀ79.1 (dd, 1F, 2J(F2(trans)
,
F1) = 60 Hz, 2J(F2(trans)
,
2
1J(C3, F3) = 277 Hz, 2J(C3, F2) = 36 Hz, 3J(C3, F1) = 5 Hz, C3,
F2(cis)) = 26 Hz, F2(trans), alkenyl), ꢀ98.6 (ddm, 1F, J(F2(cis)
,
3
alkenyl), 110.2 (d, J(C1, F) = 9 Hz, C1).
F1) = 127 Hz, 2J(F2(cis), F2(trans)) = 26 Hz, F2(cis), alkenyl),
3

1322
A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
ꢀ104.3 (dd, 1F, 3J(F, H2) = 8 Hz, 3J(F, H4) = 7 Hz, m-C6H4F),
o-C6H4F), ꢀ146.6 (s, 4F, BF4); 11B NMR (CH2Cl2, 24 8C) d
ꢀ2.1 (s, BF4, t1/2 = 4 Hz); 1H NMR (CH2Cl2, 24 8C) d 8.3 (dd,
1H, 3J(H3, F) = 7 Hz, 3J(H3, H4) = 7 Hz, H3(o-C6H4F)), 8.2 (m,
2H), 7.9–7.8 (m, 2H), 7.7 (m, 2H), 7.6 (m, 2H); 13C{1H} NMR
(CH2Cl2, 24 8C) d 160.5 (d, 1J(C2, F2) = 254 Hz, C2), 137.9 (s,
3
ꢀ143.2 (s, 4F, BF4). ꢀ158.1 (dd, 1F, J(F1, F2(cis)) = 127 Hz,
3J(F1, F2(trans)) = 60 Hz, F1, alkenyl); 11B NMR (CH2Cl2,
24 8C) d ꢀ2.2 (s, BF4); 1H NMR (CH2Cl2, 24 8C) d 8.8 (m, 1H),
8.0 (m, 1H), 7.8 (m, 1H), 7.6 (m, 1H); 13C{1H} NMR (CH2Cl2,
0
0
1
3
24 8C) d 163.0 (d, J(C3, F3) = 258 Hz, C3, aryl), 155.3 (ddd,
C5), 136.4 (d, J(C6, F) = 8 Hz, C6), 135.9 (s, C3 ,5 , phenyl),
40
20,60
1J(C2, F2(cis)) = 312.4 Hz, 1J(C2, F2(trans)) = 289 Hz, 2J(C2,
F1) = 32 Hz, C2, alkenyl), 134.2 (d, 3J(C5, F) = 8 Hz, C5),
133.5(s, C , phenyl), 132.9 (s, C , phenyl), 127.8 (d, 3J(C40,
F) = 3 Hz, C4), 117.3 (d, J(C3, F) = 22 Hz, C3), 112.7 (s, C1 ,
phenyl), 98.5 (d, J(C1, F) = 23 Hz, C1).
2
4
2
2
132.2 (d, J(C6, F) = 4 Hz, C6), 123.4 (d, J(C2, F) = 26 Hz,
C2), 121.8 (d, 2J(C4, F) = 21 Hz, C4), 111.2 (d, 3J(C1,
F) = 8 Hz, C1), 100.5 (ddd, 1J(C1, F1) = 324 Hz, 2J(C1,
m-Fluorophenyl(phenyl)iodonium tetrafluoroborate pre-
pared from 800 mg (3.076 mmol) m-C6H4FIF2 and 370 mg
(2.93 mmol) C6H5BF2 in 15 ml CH2Cl2; yield 750 mg (66.2%)
isolated from the primary precipitation and 297 mg
(0.77 mmol, 26.3%) from the mother liquor; overall yield
1047 mg, 92.5%; melting point 125–127 8C.
F2(trans)) = 63 Hz, J(C1, F2(cis)) = 30 Hz, C1, alkenyl).
2
p-Fluorophenyl(perfluorovinyl)iodonium tetrafluoroborate
prepared from 1050 mg (4.04 mmol) p-C6H4FIF2 479.7 mg
(3.69 mmol) and CF2 CFBF2 in 15 ml CH2Cl2; yield 940 mg
(2.41 mmol, 65.3%) isolated from the primary precipitate and
410 mg (1.05 mmol, 28.5%) from the mother liquor; overall
yield 1350 mg (3.46 mmol, 93.8%).
[m-C6H4F(C6H5)I][BF4] 19F NMR (CH2Cl2, 24 8C) d
ꢀ105.2 (ddd, 1F, 3J(F, H2) = 8 Hz, 3J(F, H4) = 7 Hz, 4J(F,
1
H5) = 6 Hz, m-C6H4F), ꢀ146.0 (q, 4F, J(BF4, BF4) = 2 Hz,
[p-C6H4F(CF2 CF)I][BF4] 19F NMR (CH2Cl2, 24 8C) d
BF4); 11B NMR (CH2Cl2, 24 8C) d ꢀ2.1 (q, 1J(BF4,
ꢀ79.0 (dd, 1F, 3J(F2(trans)
,
F1) = 60 Hz, 2J(F2(trans)
,
BF4) = 1 Hz, BF4); H NMR (CH2Cl2, 24 8C) d 8.2 (m, 1H),
1
F2(cis)) = 27 Hz, F2(trans), alkenyl), 98.9 (dd, 1F, 3J(F2(cis)
,
8.2 (m, 1H), 8.0 (m, 1H), 7.9 (m, 1H), 7.9 (m, 1H), 7.7–7.6 (m,
3H), 7.5 (m, 1H); 13C{1H} NMR (CH2Cl2, 24 8C) d 163.5 (d,
F1) = 127 Hz, 2J(F2(cis), F2(trans)) = 27 Hz, F2(cis), alkenyl),
ꢀ101.7 (m, 1F, p-C6H4F), ꢀ143.9 (s, 4F, BF4) ꢀ157.9 (dd,
1F, 3J(F1, F2(cis)) = 127 Hz, 3J(F1, F2(trans)) = 60 Hz, F1, alkenyl);
11B NMR (CH2Cl2, 24 8C) d ꢀ2.1 (s, BF4); 1H NMR (CH2Cl2,
24 8C) d 8.3 (m, 2H, H3,5), 7.5 (m, 2H, H2,6); 13C{1H} NMR
(CH2Cl2, 24 8C) d 166.1 (d, 1J(C4, F4) = 258 Hz, C4, aryl), 155.1
0
0
1J(C3, F3) = 257 Hz, C3), 136.3 (s,0 C2 ,6 , phenyl), 134.2 (d,
0
0
4J(C5, F) = 8 Hz, C5), 133.9 (s, C4 , phenyl), 133.2(s, C3 ,5
,
phenyl), 131.8 (d, 4J(C6, F) = 3 Hz, C6), 123.1 (d, 2J(C20,
F) = 26 Hz, C2), 121.0 (d, 2J(C4, F) = 21 Hz, C4), 112.8 (s, C1 ,
3
phenyl), 111.3 (d, J(C1, F) = 8 Hz, C1).
1
1
2
(ddd, J(C2, F2(cis)) = 312.2, J(C2, F2(trans)) = 289 Hz, J(C2,
p-Fluorophenyl(phenyl)iodonium tetrafluoroborate pre-
pared from 710 mg (2.73 mmol) p-C6H4FIF2 and 342 mg
(2.72 mmol) C6H5BF2 in 15 ml CH2Cl2; yield 520 mg
(1.35 mmol, 49.5%) isolated from the primary precipitation
and 430 mg (1.11 mmol, 41.0%) from the mother liquor;
overall yield 950 mg, 90.5%; melting point 134–136 8C.
[p-C6H4F(C6H5)I][BF4] 19F NMR (CH2Cl2, 24 8C) d
ꢀ104.6 (tt, 1F, 3J(F, H3,5) = 8 Hz, 4J(F, H2,6) = 5 Hz, p-
C6H4F), ꢀ145.8 (q, 4F, 1J(BF4, BF4) = 2 Hz, BF4); 11B
F1) = 32 Hz, C2, alkenyl), 139.1 (d, J(C2,6, F) = 10 Hz, C2,6),
3
120.7 (d, J(C3,5, F) = 23 Hz, C3,5), 105.8 (s, C1), 100.6 (ddd,
2
1J(C1, F1) = 324 Hz, 2J(C1, F2(trans)) = 63 Hz, 2J(C1,
F2(cis)) = 29 Hz, C1, alkenyl).
4.3.4. Preparation of monofluorophenyl(phenyl)iodonium
tetrafluoroborates, [o-, m-, and p-C6H4F(C6H5)I][BF4],
general procedure
1
Monofluoro(difluoroiodo)benzenes (2–3 mmol) were dis-
solved in CH2Cl2 (12 ml) at 20 8C in a 23 mm i.d. FEP trap.
Under intensive stirring 90–95% of the equimolar quantity of
phenyldifluoroborane was added as CH2Cl2 solution (concen-
tration approximately 0.24 mmol/ml) in five equal portions
within 20 min. The resulting suspension was stirred for
additional 0.5 h. The mother liquor was separated from the
light yellowish solid. The solid was washed with CH2Cl2 at
ꢀ50 8C (2 ꢈ 5 ml) and dried in vacuum at ꢁ 20 8C. The
NMR (CH2Cl2, 24 8C) d ꢀ2.0 (q, J(BF4, BF4) = 2 Hz, BF4);
1H NMR (CH2Cl2, 24 8C) d 8.3–8.1 (m, 4H), 7.8 (m, 1H), 7.7
(m, 2H), 7.4 (m, 2H); 13C{1H} NMR (CH2Cl2, 24 8C) d 165.1
(d, 1J(C4, F4) = 256 Hz, C4), 138.1 (d, 3J(C2,6, F) = 9 Hz, C2,6),
0
0
0
0
0
0
135.9 (s, C2 ,6 , phenyl), 133.7 (s, C4 , phenyl), 133.1 (s, C3 ,5
,
phenyl), 119.9 (d, 2J(C3,5, F) = 23 Hz, C3,5), 113.2 (s, C1 ,
phenyl), 105.8 (s, C1).
4.3.5. The reaction of p-C6H4FIF2 with C6H5PF4
1
products were characterized by 19F, 13C, H, and 11B spectro-
A solution of freshly prepared C6H5PF4 (187.7 mg,
1.020 mmol) in CH2Cl2 (1 ml; ꢀ78 8C) was added to a stirred
cold solution of p-C6H4FIF2 (263.7 mg, 1.014 mmol) in
CH2Cl2 (2 ml, ꢀ60 8C). Immediately a blue colored solution
resulted which turned colorless when intensively stirred for
some minutes at ꢀ60 8C. Following the solvent was removed in
HV (ꢆ ꢀ78 8C) and the solid was dried in HVat 20 8C for 2 h.
Yield of [p-C6H4F(C6H5)I][PF6] 420 mg (0.946 mmol, 93.3%);
melting point 125–126 8C.
scopy. The melting points of the products were determined in
sealed glasscapillariesunder argon. Thesaltswere stored undera
dry atmosphere of argon at ambient temperature.
o-Fluorophenyl(phenyl)iodonium tetrafluoroborate pre-
pared from 710 mg (2.73 mmol) o-C6H4FIF2 and 340 mg
(2.70 mmol) C6H5BF2 in 15 ml CH2Cl2; yield 520 mg
(1.35 mmol, 49.9%) isolated from the primary precipitation
and 416 mg (1.08 mmol, 40.0%) from the mother liquor;
overall yield 936 mg, 89.9%; melting point: 140–142 8C.
[o-C6H4F(C6H5)I][BF4] 19F NMR (CH2Cl2, 24 8C) d ꢀ95.5
[p-C6H4F(C6H5)I][PF6] 19F NMR (CH2Cl2; 24 8C) d ꢀ69.8
(d, 6F, 1J(PF6, PF6) = 714 Hz, PF6), ꢀ103.5 (m, 1F, p-C6H4F);
1H NMR (CH2Cl2, 24 8C); d 8.2–8.1 (m, 4H), 7.8 (m, 1H), 7.6
3
4
4
(ddd, 1F, J(F, H3) = 8 Hz, J(F, H4) = 6 Hz, J(F, H6) = 6 Hz,

A. Abo-Amer et al. / Journal of Fluorine Chemistry 127 (2006) 1311–1323
1323
(m, 2H), 7.3 (m, 2H); 31P NMR (CH2Cl2, 24 8C) d ꢀ144.4 (sep,
[17] T. Bunic, G. Tavcar, M. Tramsek, B. Zemva, Inorg. Chem. 45 (2006)
1038–1042.
1
1P, J(PF6, PF6) = 715 Hz, PF6).
[18] B. Zemva, in: R.B. King (Ed.), Encyclopedia of Inorganic Chemistry, vol.
5, Wiley, New York, 1994, pp. 2660–2680.
4.3.6. The reaction of C6F5IF2 with C6H5PF4
[19] H.-J. Frohn, S.J. Jakobs, Chem. Soc. Chem. Commun. (1989) 625–
627.
In a similar way C6H5PF4 (0.288 mmol) in CH2Cl2 (0.3 ml,
ꢀ60 8C) was added slowly to C6F5IF2 (47.9 mg, 0.144 mmol)
in CH2Cl2 (0.3 ml, ꢀ60 8C). After 2 h the 19F NMR spectrum
of the resulting solution showed that C6F5IF2 was quantitatively
consumed. The solvent was removed in vacuum and the solid
residue was washed five times with n-pentane (each 0.5–1 ml).
[C6F5(C6H5)I][PF6] (69.3 mg, 0.135 mmol) was isolated in
94% yield. The melting point was determined by DSC: Tonset
118 8C (endothermal process).
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[C6F5(C6H5)I][PF6] 19F NMR (CH2Cl2; 24 8C) d ꢀ69.3 (d,
6F, 1J(F, P) = 715 Hz, PF6), ꢀ120.4 (m, 2F, F2,6, C6F5), ꢀ139.9
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Acknowledgements
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We gratefully acknowledge financial support by the
Deutsche Forschungsgemeinschaft and the Fonds der Che-
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