19F and 13C GIAO-NMR chemical shifts for the identification of perfluoro-quinoline and -isoquinoline derivatives

Article abstract of DOI:10.1016/j.jfluchem.2013.05.005

Reaction of perfluoroquinoline 1 and perfluoroisoquinoline 2 with benzylamine gave mono- and di-aminated quinoline and isoquinoline systems, respectively, depending upon the reaction conditions by selective S _NAr processes. Optimised model geom

Full text of DOI:10.1016/j.jfluchem.2013.05.005

Journal of Fluorine Chemistry 155 (2013) 62–71
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
19F and C GIAO-NMR chemical shifts for the identification of
13
perfluoro-quinoline and -isoquinoline derivatives
b
Mark A. Fox a, Graham Pattison a, Graham Sandford a, , Andrei S. Batsanov
*
a Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
b Chemical Crystallography, Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
A R T I C L E I N F O
A B S T R A C T
Article history:
Reaction of perfluoroquinoline 1 and perfluoroisoquinoline 2 with benzylamine gave mono- and di-
aminated quinoline and isoquinoline systems, respectively, depending upon the reaction conditions by
selective SNAr processes. Optimised model geometries of the aminated derivatives at MP2/6-31G* were
Received 18 March 2013
Received in revised form 7 May 2013
Accepted 8 May 2013
in very good agreement with available X-ray crystallographic data and were used to compute 19F and 13
C
Available online 17 May 2013
GIAO-NMR shifts. Comparison with observed 19F and 13C NMR shifts give excellent correlations,
indicating that 19F and 13C GIAO-NMR computations are powerful tools in structurally identifying
polyfunctional, polycyclic perfluoroheteroaromatic compounds and aiding NMR resonance assignment.
ß 2013 Elsevier B.V. All rights reserved.
Keywords:
Perfluoroheteroaromatic
Nucleophilic aromatic substitution
Perfluoroquinoline
NMR spectroscopy
1. Introduction
Consequently, simple and accurate methods of product identifica-
tion for products derived from SNAr processes involving per-
The chemistry of perfluoroheteroaromatic derivatives has
developed considerably since the first efficient synthesis of the
most simple member of this chemical class, pentafluoropyridine,
was reported in the 1960s and many reactions of perfluoroheter-
oaromatic systems, principally nucleophilic aromatic substitution
processes, have been described [1]. Indeed, a wide range of
macrocycles [2], polysubstituted polyfluorinated systems [3],
biologically active heterocyclic systems [4], glycosyl donors [5]
and ring-fused derivatives [6] have been prepared recently using
SNAr chemistry. The product identification arising from many SNAr
processes involving monocyclic perfluoroaromatic substrates,
such as pentafluoropyridine, is relatively simple to establish by
19F NMR spectroscopic analysis due to large chemical shift
differences associated with fluorine atoms ortho, meta and para
to ring nitrogen of the highly fluorinated heterocyclic product [2–
6]. However, product identification and spectral assignments by
19F NMR spectroscopy of more complex polycyclic substrates such
as perfluoro-quinoline and -isoquinoline can be ambiguous due to
the complexity of their 19F NMR spectra because of the similar
coupling constant ranges for fluorine atoms ortho and para to
one another, limiting development of the chemistry of these
potentially very useful polyfluorinated heteroaromatic scaffolds.
fluorinated polycyclic substrates are required for the chemistry of
perfluoroheteroaromatic systems to develop further.
The use of 1H and 13C GIAO-NMR shift computations for the
structural characterisation of many organic systems have been
shown to be highly effective for accurate compound identification
[7,8]. However, 19F NMR shift computations have not been widely
used for compound identification [7,9,10]. In this paper, we explore
the use of GIAO-NMR calculations for 19F and 13C NMR chemical
shift predictions and subsequent structural confirmation and
spectral assignment of products derived from representative
model perfluoro-quinoline 1 and -isoquinoline 2 in comparison
with appropriate unambiguous X-ray crystallographic analysis
where possible.
Perfluoro-quinoline 1 and -isoquinoline 2 were synthesised
some years ago [11] and a very limited number of nucleophilic
aromatic substitution processes have been reported [12,13]
involving 1 and 2 as substrates. Reaction of perfluoroquinoline
with ammonia and perfluorocarbanionic nucleophiles give, in
general, mixtures of products derived from substitution at the 2-
and 4-positions depending upon the nature of the nucleophile [13].
Perfluoroisoquinoline 2 is reported to react with oxygen and
nitrogen nucleophiles to give products arising from substitution at
the 1-position whereas sulfur nucleophiles are less selective and
give predominantly products substituted at the 6-position,
providing an indication of the synthetic possibilities of these
scaffolds for further chemistry upon development of suitable
* Corresponding author. Tel.: +44 191 334 2039; fax: +44 191 384 4737.
E-mail address: graham.sandford@durham.ac.uk (G. Sandford).
0022-1139/$ – see front matter ß 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jfluchem.2013.05.005

M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
63
simple structural identification techniques [13]. Previous identifi-
cation of substituted derivatives of 1 and 2 have relied exclusively
on 19F NMR spectra where some shifts were assumed by
comparison with related hydrocarbon analogues, by the use of
the substituent chemical shift (SCS) method and fluorine-fluorine
or carbon-fluorine couplings which can aid NMR resonance
assignments.
Monosubstituted isomer 4, derived from substitution of fluorine at
the 4-position, was deduced by comparison with the structure of
disubstituted 5.
By a similar process, reaction of perfluoroisoquinoline 2 with
two equivalents of benzylamine in THF at reflux temperature gave
two monosubstituted products 6 and 7 in the ratio of 6:1 by 19F
NMR analysis of the crude product mixture. X-ray diffraction
analysis of crystals of the major isomer confirmed the structure of
6 (Fig. 3), arising from substitution at C-1, while the minor isomer
was the 6-substituted derivative 7. Reaction of isoquinoline 2 in
neat benzylamine gave a single disubstituted product 8 in high
yield. The identities of 7 and 8 were determined by computations
vide infra.
Molecular structures for 3, 5 and 6 are shown in Figs. 1–3 and
selected bond lengths are listed in Tables 1 and 2. The quinoline or
isoquinoline moieties are planar and the adjacent nitrogen atoms
always have planar-trigonal (sp2) geometry where the planes
practically coincide with the perfluoroaromatic rings, resulting in
2. Results and discussion
Reactions of perfluoro-quinoline 1 and -isoquinoline 2 with
benzylamine, selected as the model primary amine nucleophile
due to the likely formation of suitable crystals of the substituted
products for corroborative X-ray crystallography, are collated in
Scheme 1. Heating a solution of perfluoroquinoline with two
equivalents of benzylamine in THF led to two products 3 and 4
in an approximately 4:3 ratio. Separation and isolation of these
products was possible using column chromatography and X-ray
crystallography (Fig. 1) confirmed the structure of major
product 3 arising from substitution of fluorine located at the 2-
position. Reaction of 1 in neat benzylamine at ambient tempera-
ture gave a single disubstituted product and X-ray diffraction
confirmed the structure of 2,4-disubstituted quinoline 5 (Fig. 2).
substantial
p-conjugation indicated by shortened C–N bond
distances [15]. Such conformations maximise intramolecular N–
Hꢀ ꢀ ꢀF interactions. Generally, ‘organic’ fluorine is regarded to be a
poor acceptor of hydrogen bonds [16], participating in such
interactions only in the absence of any more effective acceptor but,
Scheme 1. Reactions of perfluoro-quinoline 1 and -isoquinoline 2 with benzylamine.

64
M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
Fig. 1. Molecular structure of N-benzyl-3,4,5,6,7,8-hexafluoroquinolin-2-amine 3,
showing thermal ellipsoids (at the 50% probability level) and intermolecular
contacts. Torsion angle C(2)–N(2)–C(1)–C(11) 111.1(2)8. Symmetry operation (1):
1 ꢁ x, 1/2 + y, 1/2 ꢁ z. Drawn using OLEX2 graphics [14].
in 3, 5 and 6, such acceptors are seemingly available in the form of
heterocyclic N atoms. Structures 5 and 6 show no N–Hꢀ ꢀ ꢀN bonding
although 3 contains an intermolecular contact H(2N)ꢀ ꢀ ꢀN(1)
(Fig. 1). This is too long to be considered a hydrogen bond
˚
˚
(2.35 A, assuming the idealised N–H bond length of 1.03 A [17],
compared to the usual range for N–Hꢀ ꢀ ꢀN hydrogen bonds (1.8–
˚
2.1 A) [18]) and is directed at 578 to the quinoline plane (i.e. is not
directed along the N(1) lone electron pair). In 5, H(2N) forms an
intermolecular contact with a phenyl carbon atom along the
Fig. 3. Molecular structure of N-benzyl-3,4,5,6,7,8-hexafluoroisoquinolin-1-amine 6.
Torsion angle C(1)–N(1)–C(11)–C(Ph) 161.0(1)8.
˚
direction of its p
˚
p
orbital, at 2.72 A (cf. the sum of van der Waals
radii of 2.87 A [12]). In both cases, the intramolecular NHꢀ ꢀ ꢀF
contact is shorter than N–Hꢀ ꢀ ꢀN contacts, if awkwardly directed,
while H(3N) in 5 and H(1N) in 6 indisputably form intramolecular
Table 1
Comparison of observed (X-ray) bond distances in perfluoroquinolines 3 and 5 and
calculated values for 3a and 5a.
3
3a
5
5a
N(1)–C(2)
N(1)–C(9)
C(2)–C(3)
C(3)–C(4)
C(4)–C(10)
C(10)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(2)–N(2)
C(4)–N(3)
F(3)ꢀ ꢀ ꢀH(2N)
F(5)ꢀ ꢀ ꢀH(3N)
1.321(2)
1.364(2)
1.431(2)
1.352(2)
1.420(2)
1.407(2)
1.362(2)
1.398(2)
1.368(2)
1.407(2)
1.422(2)
1.350(2)a
1.327
1.364
1.428
1.365
1.420
1.410
1.379
1.405
1.379
1.415
1.432
1.356a
1.321(1)
1.359(1)
1.416(2)
1.375(2)
1.455(1)
1.411(2)
1.369(2)
1.394(2)
1.361(2)
1.415(2)
1.426(2)
1.362(1)a
1.360(1)a
2.27(2)c
1.93(2)c
1.325
1.362
1.418
1.380
1.446
1.413
1.379
1.402
1.378
1.416
1.434
1.369b
1.380b
2.26
2.30(3)c
2.33
1.91
Fig. 2. Molecular structure of N2,N4-benzyl-3,5,6,7,8-pentafluoroquinolin-2,4-diamine
5. Torsion angles (8): C(2)–N(2)–C(1)–C(Ph) 167.7(1), C(4)–N(4)–C(20)–C(Ph)
179.1(1). Symmetry operation (1): 1 ꢁ x, ꢁy, 1 ꢁ z.
a
N atom planar.
b
N atom pyramidal.
c
˚
N–H bond length corrected to 1.03 A [13].

M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
65
Table 2
It is noteworthy that individual, even sterically disparate,
arenes and perfluoroarenes nearly always co-crystallise in a 1:1
ratio, such as exists (intramolecularly) in 3 and 6. Compound 5,
however, which contains two arene groups for each perfluoroar-
ene, adopts an entirely different packing motif (Fig. 5) with
effectively segregated components. Rigorously parallel quinoline
moieties form a stack with near-uniform interplanar separations
Comparison of observed (X-ray) bond distances in perfluoroisoquinoline 6 and
calculated values for 6a.
6
6a
C(1)–N(2)
C(1)–C(9)
N(2)–C(3)
C(3)–C(4)
C(4)–C(10)
C(10)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(1)–N(1)
F(8)ꢀ ꢀ ꢀH(1N)
1.324(2)
1.452(2)
1.324(2)
1.353(2)
1.411(2)
1.411(2)
1.361(2)
1.394(2)
1.364(2)
1.407(2)
1.427(2)
1.354(2)a
1.99(2)c
1.332
1.446
1.332
1.372
1.414
1.415
1.378
1.404
1.378
1.410
1.435
1.363b
1.94
˚
(3.28–3.29 A), running parallel to the crystallographic x direction.
Stacks are arrayed alongside one another in the y direction and,
between them, segregated phenyl groups form layers parallel to
the (0 0 1) plane. Within these layers, phenyl rings form contacts
of both the offset face-to-face type (planes parallel, interplanar
˚
separation 3.42 A) and the herringbone type (interplanar angles
ca. 508).
Consequently, with compounds 3, 5 and 6 in hand and their
structures unambiguously confirmed by X-ray crystallography, we
were in a position to determine whether computations could be
used for product identification by comparison of experimental and
calculated NMR resonance data derived from optimised structural
geometry calculations. To reduce computational efforts using the
computationally-demanding ab initio MP2 method, optimised
model geometries of structures 3a, 5a and 6a – where each phenyl
group was replaced with a hydrogen atom – were used to
computationally model products 3, 5 and 6 respectively. Selected
parameters of structures obtained experimentally 3–6 with those
obtained computationally 3a–6a are listed in Tables 1 and 2 for
comparison. The agreement between experimental and computed
data for 3, 5 and 6 in Tables 1 and 2 are excellent with differences of
a
N atom planar.
b
N atom pyramidal.
c
˚
N–H bond length corrected to 1.03 A [13].
N–Hꢀ ꢀ ꢀF hydrogen bonds. This situation could be due to the
heterocyclic nitrogen atoms becoming sterically masked by the
adjacent substituents and their being electrophilicity depleted by
electronegative fluorine atoms, but could also indicate that the
polarisability of organic fluorine is underestimated [19].
The crystal packing of 3 and 6 (Fig. 4) resemble those of arene-
perfluoroarene co-crystals (molecular complexes) [20], comprising
slanted stacks of alternating, nearly parallel (within 5.68 in 3 and
1.58 in 6) hexafluoroquinoline (or -isoquinoline) and phenyl
moieties, with practically uniform interplanar separations averag-
˚
less than 0.02 A in all bond lengths. The agreement in the
intramolecular hydrogen-fluorine distances between 3, 5, 6 and 3a,
5a and 6a respectively is also excellent. Consequently, these
calculations confirm that the MP2-optimised model geometries
3a–8a can effectively predict the geometries of 3–8 given the
agreement between computational and experimental data sets.
Observed and computed 19F NMR shift data for the perfluoro-
quinoline and -isoquinoline derivatives 1–8 are collated in Tables 3
and 4. The MP2-optimised model geometries of 3a–8a were used
to calculate 19F and 13C GIAO-NMR chemical shifts for the
corresponding phenyl derivatives 3–8. Calculated 19F NMR shifts
with an error range between 4.9 and ꢁ4.7 ppm (within a range
˚
˚
ing 3.31 A in 3 and 3.43 A in 6. The tighter stacking in 3, results in it
having a higher overall density (by ca. 1%), and a melting
temperature 15 8C higher than its isomer 6.
Fig. 4. Stacking motifs of 3 and 6. Hydrogen atoms are omitted for clarity.

66
M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
Fig. 5. Crystal packing of 5. Hydrogen atoms are omitted for clarity.
Table 3
Calculated and observed 19F NMR chemical shifts for perfluoroquinoline derivatives.
Resonance
1 Calc.
1 Observed
3a Calc.
3 Observed
4a Calc.
4 Observed
5a Calc.
5 Observed
F-2
F-3
F-4
F-5
F-6
F-7
F-8
ꢁ72.5
ꢁ163.4
ꢁ124.0
ꢁ146.6
ꢁ155.5
ꢁ152.0
ꢁ148.2
ꢁ72.9
ꢁ161.3
ꢁ124.6
ꢁ146.5
ꢁ154.8
ꢁ151.0
ꢁ148.8
–
–
ꢁ82.3
ꢁ80.2
ꢁ164.6
–
–
–
ꢁ166.7
ꢁ138.8
ꢁ149.6
ꢁ166.0
ꢁ157.6
ꢁ156.5
ꢁ163.9
ꢁ137.5
ꢁ148.7
ꢁ163.7
ꢁ155.4
ꢁ153.1
ꢁ168.2
ꢁ165.9
ꢁ163.2
–
ꢁ152.4
ꢁ164.4
ꢁ158.6
ꢁ148.4
ꢁ149.0
ꢁ160.3
ꢁ154.6
ꢁ148.4
ꢁ152.2
ꢁ169.6
ꢁ160.3
ꢁ153.7
ꢁ150.1
ꢁ167.8
ꢁ158.6
ꢁ153.4
Table 4
Calculated and observed 19F NMR chemical shifts for perfluoroisoquinoline derivatives.
Resonance
2 Calc.
2 Observed
6a Calc.
6 Observed
7a Calc.
7 Observed
8a Calc.
8 Observed
F-1
F-3
F-4
F-5
F-6
F-7
F-8
ꢁ63.0
ꢁ94.4
ꢁ62.1
ꢁ96.8
–
–
ꢁ66.8
ꢁ97.4
ꢁ65.6
ꢁ99.9
ꢁ159.3
ꢁ147.2
–
–
–
ꢁ95.8
ꢁ96.4
ꢁ98.5
ꢁ179.2
ꢁ145.3
ꢁ101.3
ꢁ175.6
ꢁ147.7
–
ꢁ156.0
ꢁ146.2
ꢁ147.1
ꢁ155.2
ꢁ138.7
ꢁ155.7
ꢁ145.9
ꢁ145.4
ꢁ153.1
ꢁ139.9
ꢁ176.4
ꢁ146.8
ꢁ153.7
ꢁ164.2
ꢁ146.0
ꢁ172.3
ꢁ146.8
ꢁ150.6
ꢁ159.3
ꢁ143.0
ꢁ160.6
ꢁ148.6
ꢁ152.8
ꢁ144.4
ꢁ150.5
ꢁ144.2
ꢁ156.6
ꢁ147.7
ꢁ156.8
ꢁ148.2

M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
67
Table 5
Calculated and observed 13C NMR chemical shifts for perfluoroquinoline derivatives.
Resonance
1 Calc.
1 Observed
3a Calc.
3 Observed
4a Calc.
4 Observed
5a Calc.
5 Observed
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
151.1
134.2
150.8
140.4
140.0
142.3
142.7
126.6
108.3
152.6
133.7
152.0
140.5
139.5
142.0
141.9
127.2
107.8
149.0
134.8
147.4
140.8
137.1
142.1
141.6
130.3
104.2
149.3
135.2
148.0
140.5
136.3
141.3
140.8
130.9
102.1
152.0
130.3
141.1
143.7
137.9
140.7
143.2
128.2
106.4
154.1
130.4
140.3
143.4
137.7
140.5
141.9
128.7
107.5
150.5
134.9
134.4
144.4
136.4
140.8
142.6
131.2
105.3
150.2
133.8
134.1
143.7
134.5
139.8
140.7
132.3
104.7
Table 6
Calculated and observed 13C NMR chemical shifts for perfluoroisoquinoline derivatives.
Resonance
2 Calc.
2 Observed
6a Calc.
6 Observed
7a Calc.
7 Observed
8a Calc.
8 Observed
C-1
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
148.5
145.6
135.6
140.8
143.0
139.3
142.7
104.5
118.0
149.6
145.0
135.3
141.0
143.4
139.3
142.3
104.2
119.8
148.5
148.5
128.9
141.1
141.5
137.0
144.7
101.6
118.3
148.1
148.2
128.5
141.2
141.7
137.4
144.2
103.2
119.3
148.7
145.8
134.6
138.4
130.8
139.6
142.1
101.3
119.2
149.9
144.7
133.5
137.8
131.2
140.2
141.8
103.2
119.7
148.6
148.6
128.1
140.4
130.4
139.8
145.7
99.6
147.9
147.7
127.2
139.4
129.0
138.6
144.2
98.5
117.6
118.5
between ca. ꢁ70 and ꢁ170 ppm in 19F NMR) (see Fig. 6) suggest
that these computations are accurate enough to aid 19F NMR peak
assignments and unambiguously determine structure identifica-
tion. Resonance assignments, therefore, were based on calculated
values of 19F and 13C NMR shifts and were further confirmed by the
measurement of appropriate coupling constants such as peri JFF
and ortho JFF being in the ranges of ca. 50–60 Hz and 15–20 Hz,
respectively.
Similarly, observed 13C NMR resonances using 19F-selective-
decoupled 13C NMR experiments and computed 13C NMR shift data
for perfluoro-quinoline and -isoquinoline derivatives 1–8 are
collated in Tables 5 and 6. The correlation between observed and
computed 13C NMR shifts, with an error range between 2.1 and
ꢁ2.1 ppm (within a range between ca. 50 and 150 ppm in 13C
NMR), suggest that GIAO-NMR calculations of 13C NMR chemical
shifts can be used with a high degree of confidence for reliable
160
-180
-160
-140
-120
-100
-80
Largest shift differences: +2.1 / -2.1 ppm
Line fitting value, R = 0.998
Largest shift differences: +4.9 / -4.7 ppm
Line fitting value, R = 0.998
150
140
130
120
110
100
-60
100
110
120
130
140
150
160
-60
-80
-100
-120
-140
-160
-180
Observed δ(19
F
)
ppm
Observed δ(13
C
)
ppm
Fig. 6. Plots of experimental 19F and 13C NMR shifts for 1–8 vs computed 19F and 13C GIAO-NMR shifts from optimised geometries.

68
M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
carbon and fluorine nuclear magnetic resonance spectra (1H NMR,
13C NMR and 19F NMR) were recorded on a Varian Inova-500 (1H
NMR, 500 MHz; 13C NMR, 126 MHz; 19F NMR, 470 MHz) or a
Varian DD-700 (1H NMR, 700 MHz; 13C NMR, 176 MHz; 19F NMR,
658 MHz) spectrometer with solvent resonance as the internal
standard (1H NMR, CHCl3 at 7.26 ppm; 13C NMR, CDCl3 at
77.36 ppm, (CD3)2SO at 40.17 ppm; 19F NMR, CFCl3 at
0.00 ppm). 1H, 13C and 19F spectroscopic data are reported as
follows: chemical shift, integration, multiplicity (s = singlet,
d = doublet, t = triplet, m = multiplet), coupling constants (Hz),
and assignment. Mass spectra were recorded on a Fisons VG-Trio
1000 Spectrometer coupled with a Hewlett Packard 5890 series II
gas chromatograph using a 25 m HP1 (methyl-silicone) column.
Elemental analyses were obtained on an Exeter Analytical CE-440
elemental analyser. Melting points were recorded at atmospheric
pressure and are uncorrected. Column chromatography was
carried out on silica gel (Merck no. 109385, particle size 0.040–
0.063 mm) and TLC analysis was performed on silica gel TLC plates
(Merck).
Table 7
Best line-fit values, R, and largest shift errors between computed NMR chemical
shifts for model monosubstituted perfluoroisoquinoline isomers and observed NMR
shifts for 7.
Position of
substituent
R value 19F
R value 13C
Largest error
(ppm) 19F
Largest error
(ppm) 13C
1-
3-
4-
5-
6-
7-
8-
0.913
0.920
0.974
0.999
0.999
0.995
0.997
0.990
0.992
0.977
0.983
0.998
0.978
0.990
46.1
40.1
13.1
6.0
3.8
4.1
4.8
5.0
1.9
5.1
5.1
2.5
4.7
5.3
product identification of perfluoroheteroaromatic derivatives.
Linear regression fits between observed and calculated NMR shifts
gave R values of 0.998 for both 19F and 13C nuclei (Fig. 4). Such a
high correlation between observed and calculated results indicate
that the computational NMR method used here is accurate [7].
The substitution pattern of minor monosubstituted isoquino-
line derivative 7 could not be determined by X-ray crystallography.
To establish its position of substitution, 19F and 13C GIAO-NMR
data on optimised geometries of all possible isomers of the
monosubstituted isoquinoline were compared with observed 19F
and 13C NMR data for 7. Table 7 lists the linear fit and major shift
error values between observed NMR data for 7 and computed
GIAO-NMR data for all isomers. The computed shifts are assumed
to be assigned in the same peak order as the observed peaks of 7. It
can be predicted with some confidence, therefore, that compound
7 is the 6-isomer from the excellent R values and the smallest shift
errors in both 19F and 13C NMR data. The 19F and 13C peak
assignments determined by 19F–19F couplings, 2D 19F–19F COSY
and 13C{19F selective} spectra for 7 are in accord with the peak
assignments of the 6-isomer by GIAO-NMR computations. As 6 is
Perfluoroquinoline 1; dF ꢁ72.9 (dd, 3JF2,F3 26.4, 4JF2,F4 26.4, F-2),
ꢁ124.6 (ddd, 3JF4,F5 47.6, 4JF2,F4 26.3, 3JF3,F4 14.5, F-4), ꢁ146.5 (ddd,
3
5
5
4JF4,F5 46.7, JF5,F6 15.4, JF5,F8 15.4, F-5), ꢁ148.8 (dd, JF5,F8 16.5,
3JF7,F8 16.5, F-8), ꢁ151.0 (ddd, 3JF6,F7 19.2, 3JF7,F8 19.2, 7JF3,F7 7.3, F-
3
3
3
7), ꢁ154.8 (dd, JF5,F6 18.8, JF6,F7 18.8, F-6), ꢁ161.3 (ddd, JF2,F3
26.4, 3JF3,F4 14.5, 7JF3,F7 7.3, F-3); C 107.8 (dd, 2JCF 9.7, 2JCF 9.7, C-10),
d
127.2 (dd, 2JCF 18.7, 2JCF 13.3, C-9), 133.7 (ddd, 1JCF 268.4, 2JCF 34.9,
2JCF 11.6, C-3), 139.5 (ddd, 1JCF 256.5, 2JCF 14.5, 2JCF 14.5, C-6), 140.5
1
1
2
(dm, JCF 258.0, C-5), 141.9 (dd, JCF 258.9, JCF 14.5, C-8), 142.0
(ddd, 1JCF 259.4, 2JCF 14.8, 2JCF 14.5, C-7), 152.0 (dm, 1JCF 276.6, C-4),
152.6 (dd, JCF 249.6, JCF 14.8, C-2).
1
2
4
5
Perfluoroisoquinoline 2; dF -62.1 (ddd, JF1,F8 63.3, JF1,F4 33.9,
4JF1,F3 11.3, F-1), ꢁ96.8 (s, F-3), ꢁ139.9 (dm, JF1,F8 60.9, F-8),
4
ꢁ145.4 (m, F-6), ꢁ145.9 (ddd, 4JF4,F5 47.4, 3JF5,F6 18.0, 5JF5,F8 18.0, F-
3
3
4
5), ꢁ153.1 (dd, JF6,F7 18.0, JF7,F8 18.0, F-7), ꢁ155.7 (ddd, JF4,F5
confirmed by X-ray crystallography as the 1-isomer and
7
47.4, 5JF1,F4 33.9, F-4);
d
C 104.2 (dd, 2JCF 30.7, 2JCF 12.4, C-9), 119.8
confirmed by GIAO-NMR as the 6-isomer, the disubstituted
derivative 8 must be the 1,6-isomer, thus ruling out the need to
explore other isomers by computations to establish its identity.
(dd, 2JCF 11.0, 2JCF 11.0, C-10), 135.3 (dd, 1JCF 259.1, 2JCF 27.1, C-4),
1
2
2
1
139.3 (ddd, JCF 258.4, JCF 15.3, JCF 15.3, C-7), 141.0 (dm, JCF
259.9, C-5), 142.3 (dm, 1JCF 270.0, C-8), 143.4 (ddd, 1JCF 263.4, 2JCF
14.6, 2JCF 14.6, C-6), 145.0 (ddd, 1JCF 243.7, 2JCF 15.0, 2JCF 15.0, C-3),
1
3. Conclusions
149.6 (dm, JCF 254.7, C-1).
Reaction of perfluoroquinoline 1 with benzylamine gave a
mixture of 2- and 4-monosubstituted quinolines and 2,4-
disubstituted quinoline was obtained upon reaction with excess
benzylamine. Perfluoroisoquinoline 2 gave a mixture of 1- and 6-
substituted isoquinolines upon reaction with benzylamine and a
1,6-disubstituted isoquinoline was isolated upon reaction with
neat benzylamine. X-ray structural analysis was used to unam-
4.2. Reactions of perfluoroquinoline with benzylamine
(a) With two equivalents of benzylamine
A
mixture consisting of perfluoroquinoline 1 (1.00 g,
3.92 mmol), benzylamine (0.86 mL, 7.88 mmol) and THF
(20 mL) was heated at reflux temperature for 4 h. The solution
was allowed to cool and water (20 mL) and DCM (20 mL) were
added. The organic layer was separated and the aqueous layer
was extracted with DCM (2 ꢂ 20 mL) and ethyl acetate
(2 ꢂ 20 mL). The combined organic extracts were dried
(MgSO4), filtered and evaporated. Column chromatography
on silica gel using hexane: DCM (2:1) as elutant gave N-benzyl-
3,4,5,6,7,8-hexafluoroquinolin-2-amine 3 (0.60 g, 44%) as white
crystals; mp 114–115 8C (Found: C, 56.4; H, 2.7; N, 8.6.
biguously identify products 3,
5 and 6. Optimised model
geometries of these compounds at MP2/6-31G* were in very good
agreement with available X-ray crystallographic data and used to
compute 19F and 13C GIAO-NMR shifts of 3–8. Computed 19F and
13C GIAO-NMR shifts were compared with observed 19F and 13C
NMR shifts for 1–8 and we find that the correlations between
experimental and calculated NMR shifts are excellent, indicating
that 19F and 13C GIAO-NMR computations are powerful tools in
identifying polyfunctional, polycyclic perfluoroheteroaromatic
compounds and aiding NMR resonance assignment.
C
16H8F6N2 requires: C, 56.2; H, 2.4; N, 8.2%); d
H 4.68 (2H, d, 3JHH
5.8, CH2), 5.44 (1H, br s, NH), 7.19–7.32 (5H, m, ArH); dF ꢁ137.5
(1F, dd, 4JF4,F5 46.2, 3JF3,F4 15.4, F-4), ꢁ148.7 (1F, ddd, 4JF4,F5 46.4,
5
3
5
3JF5,F6 20.8, JF5,F8 15.8, F-5), ꢁ153.1 (1F, dd, JF7,F8 17.8, JF5,F8
17.8, F-8), ꢁ155.4 (1F, ddd, 3JF6,F7 20.5, 3JF7,F8 20.5, 7JF3,F7 6.2, F-
7), ꢁ163.7 (1F, dd, 3JF5,F6 20.6, 3JF6,F7 20.6, F-6), ꢁ163.9 (1F, s, F-
4. Experimental
3); d
C 45.3 (s, CH2), 102.1 (dd, 2JCF 7.0, 2JCF 7.0, C-10), 127.9 (s, C-
4.1. General
20), 128.3 (s, C-40), 128.8 (s, C-30), 130.9 (d, 2JCF 7.2, C-9), 135.2
1
2
1
2
(dd, JCF 259.0, JCF 12.6, C-3), 136.3 (ddd, JCF 245.6, JCF 15.3,
2JCF 15.3, C-6), 137.8 (s, C-10), 140.5 (dm, 1JCF 253.2, C-5), 140.8
(dd, JCF 258.1, JCF 55.3, C-8), 141.3 (ddd, JCF 251.4, JCF 14.2,
Perfluoroquinoline 1 and perfluoroisoquinoline 2 were synthe-
sised following literature methods [11]. Other materials were
obtained commercially (Aldrich, Lancaster or Fluorochem). Proton,
1
2
1
2

M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
69
3
3
2JCF 14.2, C-7), 148.0 (dm, 1JCF 267.5, C-4), 149.3 (dd, 2JCF 11.7,
3JCF 3.5, C-2); m/z (EI+) 342 ([M]+, 8%), 263 (8), 236 (5), 224 (14),
186 (8), 106 (20, [NHCH2Ph]+), 91 (100, [CH2Ph]+), 77 (26); and,
N-benzyl-2,3,5,6,7,8-hexafluoroquinolin-4-amine 4 (0.44 g, 32%)
as a cream solid; mp 113–115 8C (Found: C, 56.4; H, 2.5; N, 8.2.
3JF6,F7 20.1, F-6), ꢁ159.3 (1F, ddd, JF6,F7 21.1, JF7,F8 21.1,
7JF3,F7 5.8, F-7), ꢁ172.3 (1F, dd, JF4,F5 51.3, JF3,F4 21.9, F-4);
4
3
d
C 46.4 (s, CH2), 103.2 (dd, 2JCF 9.9, 3JCF 2.5, C-9), 119.3 (m, C-
1
2
10), 128.0 (s, C-20), 128.2 (s, C-40), 128.5 (dd, JCF 249.7, JCF
28.4, C-4), 129.1 (s, C-30), 137.4 (ddd, 1JCF 256.1, 2JCF 19.9, 2JCF
1
C
16H8F6N2 requires: C, 56.2; H, 2.4; N, 8.2%);
d
H 4.76 (2H, d, 3JHH
4.8, NHCH2), 6.16 (1H, d, JHF 18.8, NHCH2), 7.24–7.34 (5H, m,
19.9, C-7), 137.9 (s, C-10), 141.2 (dm, JCF 258.1, C-5), 141.7
3
1
1
2
(dm, JCF 257.1, C-6), 144.2 (dd, JCF 248.1, JCF 17.9, C-8),
148.1 (dm, 3JCF 18.3, C-1),148.2 (dd, 1JCF 237.2, 2JCF 13.5, C-3);
m/z (EI+) 342 ([M]+, 46%), 236 (32), 224 (26), 186 (33), 91
([CH2Ph]+, 100); and, N-benzyl-1,3,4,5,7,8-hexafluoroisoquino-
lin-6-amine 7 (0.11 g, 8%) as a cream solid; dH 4.68 (3H, m,
3
3
Ar–H); dF ꢁ80.2 (1F, d, JF2,F3 27.5, F-2), ꢁ148.4 (1F, dd, JF7,F8
20.5, 5JF5,F8 15.5, F-8), ꢁ149.0 (1F, dd, 5JF5,F8 15.8, 3JF5,F6 15.8, F-
3
3
7
5), ꢁ154.6 (1F, ddd, JF6,F7 20.9, JF7,F8 20.9, JF3,F7 5.6, F-7),
ꢁ160.3 (1F, ddd, 3JF5,F6 20.9, 3JF6,F7 20.9, 7JF2,F6 4.7, F-6), ꢁ164.6
(1F, d, 3JF2,F3 28.2, F-3);
d
C 50.0 (d, 3JCF 11.0, CH2), 107.5 (s, C-10),
NH, CH2), 7.22–7.32 (5H, m, ArH); dF ꢁ65.6 (1F, ddd, JF1,F8
4
127.4 (s, C-20), 128.2 (s, C-40), 128.7 (d, 2JCF 24.8, C-9), 129.1 (s,
C-30), 130.4 (dd, 1JCF 245.7, 2JCF 31.0, C-3), 137.6 (s, C-10), 137.7
58.6, JF1,F4 30.6, JF1,F5 11.8, F-1), -99.9 (1F, m, F-3), ꢁ144.2
5
5
(1F, ddd, 4JF1,F8 58.7, 5JF5,F8 16.0, 5JF4,F8 16.0, F-8), ꢁ147.2 (1F,
1
2
2
4
5
5
(ddd, JCF 254.0, JCF 16.3, JCF 16.3, C-6), 140.3 (s, C-4), 140.5
(dm, 1JCF 265.4, C-7), 141.9 (dm, 1JCF 252.4, C-8), 143.4 (dd, 1JCF
244.5, JCF 16.3, C-5), 154.1 (dd, JCF 237.4, JCF 15.5, C-2); m/z
(EI+) 342 ([M]+, 49%), 224 (32), 186 (24), 91 ([CH2Ph]+, 100), 77
(20).
ddd, JF4,F5 51.3, JF5,F8 11.1, JF1,F5 11.1, F-5), ꢁ150.5 (1F, m,
4 5 3
F-7), ꢁ159.3 (1F, ddd, JF4,F5 51.3, JF1,F4 30.6, JF3,F4 15.5, F-
4); dC 49.3 (s, CH2), 103.2 (m, C-9), 119.7 (m, C-10), 127.7 (s,
C-40), 128.2 (s, C-20), 129.2 (s, C-30), 131.2 (m, C-6), 133.5 (dd,
2
1
2
1JCF 259, JCF 27, C-4), 137.8 (dm, JCF 243, C-7), 137.9 (s, C-
2
1
1
1
(b) With excess benzylamine
10), 140.2 (dm, JCF 253, C-8), 141.8 (dm, JCF 260, C-5), 144.7
1
3
2
1
(ddd, JCF 257.1, JCF 16, JCF 16, C-3), 149.9 (dm, JCF 265, C-
1); m/z (ASAP) 342 ([M]+, 100%).
Perfluoroquinoline 1 (1.27 g, 5 mmol) and benzylamine
(30 mL) were stirred together for 3 h at rt. The reaction mixture
was poured into water (400 mL) and filtered through celite. The
celite was washed with water and then washed with DCM
(3 ꢂ 20 mL). The organic extracts were dried (MgSO4) and
evaporated to leave a viscous brown oil. Column chromatog-
raphy on silica gel using hexane: DCM (2:1) as elutant and
recrystallisation from acetonitrile gave N2,N4-dibenzyl-
3,5,6,7,8-pentafluoroquinolin-2,4-diamine 5 (1.89 g, 88%) as a
white solid; mp 145 8C (Found: C, 64.0; H, 3.8; N, 9.6.
(b) With excess benzylamine
Perfluoroisoquinoline 1 (1.27 g, 5 mmol) and benzylamine
(30 mL) were stirred together for 3 h at rt. The reaction mixture
was poured into water (400 mL) and filtered through celite. The
celite was washed with water and DCM (3 ꢂ 20 mL). The
organic extracts were dried (MgSO4) and evaporated to leave a
viscous brown oil. Column chromatography on silica gel using
hexane: DCM (2:1) as elutant and recrystallisation from
ethanol gave N1,N6-dibenzyl-3,4,5,7,8-pentafluoroisoquinolin-
1,6-diamine 8 (1.83 g, 85%) as a white solid; mp 97–98 8C
(Found: C, 64.3; H, 3.8; N, 9.8. C23H16F5N3 requires: C, 64.3; H,
3.8; N, 9.8%); ymax (KBr)/cmꢁ1 3487, 3393, 3028, 1653, 1545,
C
23H16F5N3 requires: C, 64.3; H, 3.8; N, 9.8%); ymax (KBr)/
cmꢁ1 3487, 3426, 3031, 2892, 1663, 1631, 1543, 1506, 1491; dH
4.61 (2H, dd, J 3.8, J 3.8, CH2), 4.66 (2H, d, J 5.6, CH2), 5.14 (1H, q,
J 2.8, NH), 5.58 (1H, dt, 5JHF 18.4, NH), 7.32–7.19 (10H, m, ArH);
3
5
3
dF ꢁ150.1 (dd, JF5,F6 18.1, JF5,F8 15.8, F-5), ꢁ153.4 (dd, JF7,F8
1525; dH 4.50 (1H, br s, NH), 4.68 (2H, s, CH2), 4.69 (2H, s, CH2),
5
3
3
19.0, JF5,F8 11.9, F-8), ꢁ158.6 (ddd, JF6,F7 20.3, JF7,F8 20.3,
6.29 (1H, br s, NH), 7.40–7.29 (10H, m, ArH); dF ꢁ101.3 (d, 3JF3,F4
3
3
4
3
7JF3,F7, 4.5, F-7), ꢁ163.2 (s, F-3), ꢁ167.8 (dd, JF5,F6 21.4, JF6,F7
22.4, F-3), ꢁ147.7 (d, JF4,F5 55.7, F-5), ꢁ148.2 (dd, JF7,F8 15.6,
4
21.4, F-6); dC (d6-dmso) 44.9 (s, CH2), 50.0 (d, JCF 10.6, CH2),
5JF5,F8 11.0, F-8), ꢁ156.8 (d, 3JF7,F8 15.6, F-7), ꢁ175.6 (dd, 4JF4,F5
3
104.7 (s, C-10), 127.1 (s, C-20), 127.2 (s, C-40), 127.4 (s, C-400),
55.7, JF3,F4 22.4, F-4); dC 45.9 (s, CH2), 49.5 (s, CH2), 98.5 (dd,
128.3 (s, C-200), 128.7 (s, C-30), 129.0 (s, C-300), 132.3 (d, 2JCF 8.8,
2JCF 10.6, 3JCF 4.3, C-9), 118.5 (dd, 2JCF 8.7, 2JCF 8.0, C-10), 127.2
1
1
1
2
C-9), 133.8 (d, JCF 244.5, C-3), 134.1 (s, C-4), 134.5 (ddd, JCF
240.7, 2JCF 15.8, 2JCF 15.8, C-6), 139.8 (ddd, 1JCF 249.3, 2JCF 12.8,
2JCF 12.8, C-7), 140.7 (d, 1JCF 239.3, C-8), 140.8 (s, C-10), 141.0 (s,
C-100), 143.7 (d, JCF 256.0, C-5), 150.2 (d, JCF 13.4, C-2); m/z
(ASAP) 429 ([M]+, 100%).
(dd, JCF 247.5, JCF 27.8, C-4), 127.4 (s, C-20,200), 127.7 (s, C-
40,400), 129.0 (s, C-30), 129.1 (s, C-300), 129.0 (dd, 2JCF 1.6, 2JCF 1.3,
1
2
C-6), 138.2 (s, C-10), 138.8 (s, C-100), 138.6 (dd, JCF 244.0, JCF
12.9, C-7), 139.4 (dm, 1JCF 210.5, C-5), 144.2 (dd, 1JCF 242.7, 2JCF
1
2
1
2
3
13.3, C-8), 147.7 (dd, JCF 228.6, JCF 15.7, C-3), 147.9 (d, JCF
18.7, C-1); m/z (ASAP) 429 ([M]+, 100%).
4.3. Reactions of perfluoroisoquinoline with benzylamine
(a) With two equivalents of benzylamine
4.4. X-ray crystallography
A mixture consisting of perfluoroisoquinoline 2 (1.00 g,
3.92 mmol), benzylamine (0.8 mL, 7.32 mmol) and THF
(30 mL) was heated at reflux temperature for 4 h. After
cooling, water (20 mL) and DCM (10 mL) were added and the
organic layer was separated. The aqueous layer was
extracted with DCM (3 ꢂ 10 mL) and the combined organic
extracts were dried (MgSO4), filtered and evaporated to yield
a crude cream solid (1.04 g) containing 6 and 7 in the ratio of
6:1 by 19F NMR analysis. Column chromatography using
hexane and DCM (1:1) as elutant gave N-benzyl-3,4,5,6,7,8-
Crystals of X-ray quality were obtained by slow evaporation of
DCM solution of 3 or acetonitrile solution of 5, and by slow
diffusion of hexane into DCM solution of 6. Single-crystal X-ray
diffraction experiments (Table 8) were carried out on Bruker 3-
circle diffractometers with CCD area detectors SMART 6000 (for 3
and 6) or APEX ProteumM (for 5), using graphite-monochro-
˚
¯
mated Mo-K radiation ð ¼ 0:71073 AÞ from a sealed tube (3, 6)
l
a
or a 60 W Mo-target microfocus Bede Microsource1 X-ray
generator with glass polycapillary X-ray optics (5). Crystals
were cooled to T = 120 K using Cryostream (Oxford Cryosystems)
open-flow N2 gas cryostats. The structures were solved by direct
methods and refined by full-matrix least squares against F2 of all
reflections, using SHELXTL 6.12 software [21]. In 3 and 6, all H
atoms were refined in isotropic approximation, in 5 only the
amino ones, the rest were treated as ‘riding’ on the corresponding
C atoms.
hexafluoroisoquinolin-1-amine
6 (0.60 g, 45%) as white
crystals; mp 99–100 8C (Found: C, 56.2; H, 2.3; N, 8.3.
C
16H8N2F6 requires: C, 56.2; H, 2.4; N, 8.2%); dH 4.72 (2H, dd,
4
5
3JHH 5.2, JHF 1.5, CH2), 6.52 (1H, br d, JHF 16.1, NH), 7.14–
3
7.31 (5H, m, ArH); dF ꢁ96.4 (1F, d, JF3,F4 21.8, F-3), ꢁ143.0
3
5
4
(1F, dd, JF7,F8 19.7, JF5,F8 15.3, F-8), ꢁ146.8 (1F, ddd, JF4,F5
3
5
3
50.7, JF5,F6 19.1, JF5,F8 14.6, F-5), -150.6 (1F, dd, JF5,F6 20.1,

70
M.A. Fox et al. / Journal of Fluorine Chemistry 155 (2013) 62–71
(c) G. Sandford, C.A. Hargreaves, R. Slater, D.S. Yufit, J.A.K. Howard, A. Vong,
Table 8
Tetrahedron 63 (2007) 5204–5211;
Crystal data (T =120 K).
(d) G. Pattison, G. Sandford, D.S. Yufit, J.A.K. Howard, J.A. Christopher, D.D. Miller,
J. Org. Chem. 74 (2009) 5533–5540;
Compound
3
5
6
(e) G. Pattison, G. Sandford, D.S. Yufit, J.A.K. Howard, J.A. Christopher, D.D. Miller,
Tetrahedron 65 (2009) 8844–8850;
(f) M.W. Cartwright, L. Convery, T. Kraynck, G. Sandford, D.S. Yufit, J.A.K. Howard,
J.A. Christopher, D.D. Miller, Tetrahedron 66 (2010) 519–529;
(g) M.R. Cargill, K.E. Linton, G. Sandford, D.S. Yufit, J.A.K. Howard, Tetrahedron 66
(2010) 2356–2362;
(h) R.D. Chambers, P.A. Martin, G. Sandford, D.L.H. Williams, J. Fluorine Chem. 129
(2008) 998–1002;
(i) R.D. Chambers, G. Sandford, J. Trmcic, J. Fluorine Chem. 128 (2007)
1439–1443;
(j) M.W. Cartwright, G. Sandford, J. Bousbaa, D.S. Yufit, J.A.K. Howard, J.A. Chris-
topher, D.D. Miller, Tetrahedron 63 (2007) 7027–7035;
(k) R.E. Banks, J.E. Burgess, W.M. Cheng, R.N. Haszeldine, J. Chem. Soc. (1965)
575–581;
(l) R.D. Chambers, J. Hutchinson, W.K.R. Musgrave, J. Chem. Soc. (1964) 3736–
3739.
CCDC dep. no.
Formula
925722
C16H8F6N2
342.24
Orthorhombic
P212121 (# 19)
6.2269(5)
8.4363(6)
25.859(2)
90
925723
C23H16F5N3
439.17
925724
C16H8F6N2
343.05
Formula weight
Symmetry
Triclinic
P-1 (# 2)
7.3099(4)
10.2092(5)
15.5910(7)
88.943(3)
83.130(3)
72.420(3)
930.48(14)
2
Monoclinic
P21/n (# 14)
7.8499(1)
12.3591(2)
14.4314(2)
90
Space group (no.)
˚
a (A)
˚
b (A)
˚
c (A)
a
b
g
(8)
(8)
(8)
90
101.913(1)
90
90
3
˚
V (A )
1358.4(2)
4
1369.95(3)
4
Z
Dx (g cmꢁ3
)
1.673
1.533
1.659
m
(mmꢁ1
)
0.16
0.13
0.16
[7] K. Wolinski, J.F. Hinton, P. Pulay, J. Am. Chem. Soc. 112 (1990) 8251–8260.
[8] (a) M.W. Lodewyk, M.R. Siebert, D.J. Tantillo, Chem. Rev. 112 (2012) 1839–1862;
(b) B.S. Dyson, J.W. Burton, T. Sohn, B. Kim, H. Bae, D. Kim, J. Am. Chem. Soc. 134
(2012) 11781–11790;
Refls collected
Unique refls
Rint (%)
R(F)a, wR(F2) (%)
18588
12510
13055
2298, 2178a,b
2.3
5395, 4126a
6.2
3135, 2623a
2.2
3.0, 8.9
4.5, 12.1
3.8, 11.5
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4.5. Computations
All ab initio/DFT computations were carried out using the
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optimised at the ab initio MP2 method with a 6-31G* basis set. The
GIAO-NMR shifts were calculated at the DFT hybrid B3LYP/6-
311G* from MP2-optimised geometries. Computed 19F chemical
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verted to the usual CFCl3 scale:
NMR shifts were referenced to TMS:
d
(
19F) = 145.0 ꢁ 0.9
s
(
19F) and 13C
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Acknowledgement
(e) M.A. Fox, R. Greatrex, D.L. Ormsby, Chem. Commun. (2002) 2052–2053;
(f) S.M. Cornet, K.B. Dillon, C.D. Entwistle, M.A. Fox, A.E. Goeta, H.P. Goodwin, T.B.
Marder, A.L. Thompson, Dalton Trans. (2003) 4395–4405;
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(h) S.Z. Konieczka, A. Himmelspach, M. Hailmann, M. Finze, Eur. J. Inorg. Chem.
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We thank Dr. Dmitry S. Yufit for help with X-ray study of
compound 5.
(i) M.A. Fox, G. Sandford, R. Slater, D.S. Yufit, J.A.K. Howard, A. Vong, J. Fluorine
Chem. 143 (2012) 148–154;
Appendix A. Supplementary data
(j) M. Finze, G. Reiss, Eur. J. Inorg. Chem. (2008) 2321–2325.
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