Intramolecular C-F Activation in Schiff-Base Alkali Metal Complexes

Article abstract of DOI:10.1021/acs.organomet.8b00868

A series of alkali metal complexes (Li, Na, K) with different fluorinated phenoxo-imine ligands [M{(O-2-(RNa?CH)-C₆H₄}] [R = C₆F₅; 2,4,6-F₃C₆H₂F₃; 2,6-C₆H

Full text of DOI:10.1021/acs.organomet.8b00868

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Intramolecular C−F Activation in Schiff-Base Alkali Metal Complexes
́
Francisco M. García-Valle, Vanessa Tabernero, Tomas Cuenca, Marta E. G. Mosquera,*
́
and Jesus Cano*
́
́
́
́
Departamento de Química Organica y Química Inorganica, Instituto de Investigacion en Química “Andres M. del Río” (IQAR),
́
́
Universidad de Alcala, Campus Universitario, 28871-Alcala de Henares, Spain
S
* Supporting Information
ABSTRACT: A series of alkali metal complexes (Li, Na, K)
with different fluorinated phenoxo-imine ligands [M{(O-2-
(RNCH)-C6H4}] [R = C6F5; 2,4,6-F3C6H2F3; 2,6-C6H3F2;
2,3-C6H3F2; 2-C6H4F; 2-CF3C6H4CH2; CF3CH2] have been
synthesized and fully characterized. By using THF as solvent,
suitable crystals for X-ray diffraction analysis were obtained,
and the solid state structure of some of the prepared
compounds has been determined. This analysis reveals the
formation of a C−F bond activation product for the
potassium compound with the five-fluorinated ligand. In
stronger donor solvents, such as dimethylsulfoxide, this
process occurs immediately, independently of the metal
used. This C−F activation takes place in a smooth process
1
at room temperature. The nature of this reaction is studied by H-DOSY NMR experiments with stoichiometric amounts of
DMSO, monitoring the disaggregation process from the initial solution structure to the final activation product. The variation of
the number of fluorine atoms and their location in the iminic ring is also studied, showing their influence in this intramolecular
C−F bond activation process.
bond activation emerges as a greener and more sustainable
procedure for a broad type of substrates.6 In general, the group
s metal compound deprotonates the nucleophile, and the MNu
species formed reacts with the fluoroarene to give a C−F bond
activation and generate the corresponding C−Nu bond
(Figure 1).6a−e However, depending on the base strength or
the fluoroarene substitution, other mechanism pathways have
been observed.7
Transition metal-free C−F bond activation has been widely
used in the production of heterocyclic compounds via
intramolecular cyclization using gem-difluoroolefins, affording
5- and 6-membered heterocycles, and more recently 7-
membered rings.8 The synthesis of heterocycles from
INTRODUCTION
■
The synthesis of new fluoroaromatic compounds via C−F
bond activation has demonstrated to be important in several
applications such as pharmaceuticals, pesticides, or advanced
organic materials.1 As well, the possibility to cleave this bond is
crucial toward the degradation of fluorocarbons as a
remediation of their associated environmental problems. The
carbon fluorine (C−F) bond is the strongest bond formed by
carbon and any other element. The bond dissociation energy
makes the C−F bond relatively inert and stable, especially in
aromatic rings (CH3−F = 115 kcal·mol−1; CH3−H = 105 kcal·
mol−1; Ph−F = 127 kcal·mol−1).2
Furthermore, when directed toward different organic
transformations, a large number of C−F bond activations are
able to form new C−C bonds, although, in the presence of X−
species (O−, S−, N−), the formation of C−X bonds may take
place. The nature of these transformations has been widely
discussed in several reviews where a wide variety of approaches
have been described.3 Recently, the selective and catalytic C−F
bond cleavage mediated by transition metal complexes has
been reported.4 However, the use of transition metals implies
several drawbacks in industry, due to high costs, purification
processes, or metal toxicity which can be found in the final
products. In consequence, the use of metals with less toxicity
such as some group s metals is of great interest. In fact, these
metals have been employed successfully in C−F bond cleavage
reactions.5 As such, the nucleophilic aromatic substitution
reaction (SNAr) of fluoroarenes via transition metal-free C−F
Figure 1. Nucleophilic aromatic substitution of fluoroarenes. (a)
General procedure. (b) Intramolecular procedure.
Received: November 30, 2018
© XXXX American Chemical Society
A
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fluoroarenes as starting materials via an intramolecular SNAr
reaction is also a plausible and fast pathway; however, it has
been rarely reported.9 In this context, the use of group s metals
as transition metal-free agents is the most promising approach
to achieve these organic transformations (Figure 1b).
Schiff bases are very popular ligand precursors due to their
versatility and ease of preparation. We have already reported
several main group metal based complexes stabilized by the
presence of Schiff bases derived ligands with different steric
hindrance10 that are very active in polymerization processes.
However, the introduction of fluorine atoms in these
compounds has been scarcely reported, and only one example
of an alkali metal derivative has been found.11 The possibility
of an intramolecular SNAr reaction, as shown in Figure 1,
prompted us to study this kind of compounds. Herein, we
report the synthesis and characterization of a series of
fluorinated Schiff bases and their alkali metal derivatives.
These compounds give an intramolecular C−F bond activation
in the appropriate conditions, generating 7-membered
heterocyclic compounds. Moreover, the cleavage of the C−F
bond is straightforward and takes place at room temperature.
To our knowledge, this is one of the few cases that this C−F
activation is carried out in such mild conditions.7f,g
RESULTS AND DISCUSSION
■
By using reported synthetic methods,10 we have prepared the
perfluorinated Schiff base {La}H in high purity and good
yield.12 The 1H, 13C, and 19F NMR spectra confirm the
formation of this compound. The stoichiometric reaction
between {La}H and the corresponding metallic precursor,
[Li{N(SiMe3)2}], NaH, or [K{N(SiMe3)2}], in toluene gives
rise to the expected compounds (1−3)a (Scheme 1). After
removing the solvent, the resultant solids are washed in hexane
to eliminate the reaction byproducts and highly pure alkali
metal compounds are isolated (Scheme 1).
Figure 2. Top: ORTEP plot for 2a showing thermal ellipsoids plots
(30% probability). Hydrogen atoms are omitted for clarity. Bottom:
Core view.
Scheme 1. Synthesis of the Alkali Metal Compounds
stituted by four metallic atoms bridged by the oxygen atoms of
the Schiff bases, and gives a Na4O4 cubic core. The Na−O−Na
angles (from 85.59(11)° to 93.45(11)°) are close to 90°, in
agreement with the cubic arrangement. This class of solid state
structures have been already described for sodium com-
pounds,13 although, to the best of our knowledge, this is the
first structure reported of a fluorinated Schiff base alkali metal
compound. Both the nitrogen and the ortho fluorine atoms
establish a donor interaction with the sodium. The metal
completes its coordination sphere by coordinating one THF
molecule, and shows a distorted octahedral environment.
The Na−O bond lengths are within the usual range found in
the literature for this type of sodium compounds (see Table 1).
The shortest Na−O distances are those corresponding to the
donor interaction between the metal and the THF, whereas
the distances with the oxygen bridging atoms from the ligands
are slightly longer. Concerning Na···F interactions, the bond
lengths are remarkably different in the same molecule (Na1···
F6 = 2.5515(18) Å and Na2···F5 = 2.632(2) Å) and are quite
short and within the range observed in the literature (2.237−
3.739 Å).11b In this case, no lengthening of C−F distance
could be noticed in comparison with the fluorinated Schiff
base.12a
The final products are characterized in solution by NMR
spectroscopy and in the solid state by elemental analysis. The
1H and 19F NMR spectra are recorded in C6D6 and display a
series of broad signals due to the poor solubility of the
compounds, but good enough to confirm the formation of (1−
3)a (Figure S1; see Supporting Information). Three signals
corresponding to the different kinds of fluorine atoms (ortho,
meta, and para) present in the complexes are observed in the
19F NMR spectra. For 2a and 3a, a similar pattern in the
spectra can be noticed due to a higher similarity between the
metallic centers. However, for 1a, the spectrum is quite
different and shows one signal low-field shifted that belongs to
the ortho fluorine atoms, probably reflecting the presence of an
interaction with the metal. The addition of THF as solvent led
to the isolation of suitable single crystals for X-ray crystallo-
graphic analysis for 2a.
A THF-d8 solution of compound 3a has also been analyzed
by NMR techniques, and surprisingly, the formation of a
different compound than the expected and previously
The solid state structure for 2a is shown in Figure 2. The
molecular structure reveals a tetranuclear disposition con-
B
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a
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 2a
bond lengths (Å)
Na(1)−O(2)
Na(1)−O(2)#1
Na(1)−O(1)
Na(1)−O(3)
Na(1)−N(2)
Na(1)···F(6)
N(2)−C(22)
F(6)−C(1)
2.324(2)
2.359(2)
2.383(2)
2.441(2)
2.505(2)
2.551(2)
1.284(3)
1.346(3)
Na(2)−O(1)#1
Na(2)−O(1)
Na(2)−O(4)
Na(2)−O(2)
Na(2)−N(1)
Na(2) ···F(5)
N(1)−C(6)
2.322(2)
2.321(2)
2.400(2)
2.417(2)
2.492(2)
2.632(2)
1.291(3)
1.356(3)
F(5)−C(2)
angles (deg)
O(2)−Na(1)−O(2)#1
O(2)−Na(1)−O(1)
O(2)#1−Na(1)−O(1)
O(2)−Na(1)−O(3)
O(2)#1−Na(1)−O(3)
O(1)−Na(1)−O(3)
O(2)−Na(1)−N(2)
O(2)#1−Na(1)−F(6)
O(1)−Na(1)−F(6)
O(3)−Na(1)−F(6)
N(2)−Na(1)−F(6)
85.74(7)
92.89(7)
93.19(7)
99.08(8)
103.11(8)
160.37(8)
73.24(7)
135.89(7)
83.63(6)
77.07(7)
65.04(7)
O(1)#1−Na(2)−O(1)
O(1)#1−Na(2)−O(4)
O(1)−Na(2)−O(4)
O(1)#1−Na(2)−O(2)
O(1)−Na(2)−O(2)
O(4)−Na(2)−O(2)
O(1)#1−Na(2)−N(1)
O(1)−Na(2)−F(5)
O(4)−Na(2)−F(5)
O(2)−Na(2)−F(5)
N(1)−Na(2)−F(5)
85.54(7)
97.35(8)
102.45(8)
93.35(7)
91.93(7)
162.65(9)
72.80(7)
137.94(7)
78.16(7)
84.68(7)
63.81(7)
a
Symmetry transformations used to generate equivalent atoms: #1 −x, y, −z + 1/2.
characterized is detected. Figure 3 shows a comparative 19F
NMR spectrum of compound 3a in C6D6 and the new
Figure 4. ORTEP plot for Ox1 showing thermal ellipsoids plots (30%
probability). Hydrogen atoms are omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Ox1
Figure 3. Comparative 19F NMR spectra of compound 3a in C6D6 (a)
and THF-d8 (b) with the suggested formed compounds.
bond lengths (Å)
N(1)−C(7)
angles (deg)
C(7)−N(1)−C(15)
1.274(5)
1.405(5)
1.379(4)
1.404(4)
1.363(6)
1.390(5)
1.465(5)
121.9(3)
115.3(3)
119.8(3)
124.0(3)
130.7(4)
122.8(3)
126.3(3)
N(1)−C(15)
O(1)−C(10)
O(1)−C(1)
C(1)−C(2)
C(1)−C(6)
C(6)−C(7)
C(10)−O(1)−C(1)
C(6)−C(1)−O(1)
C(1)−C(6)−C(7)
N(1)−C(7)−C(6)
O(1)−C(10)−C(15)
C(10)−C(15)−N(1)
compound generated in THF-d8 solution. The 19F NMR
spectrum in THF-d8 shows now four resonances (Figure 3b)
that correspond to four different fluorine atoms instead of the
three expected according to that observed in C6D6 solvent
(Figure 3a). According to these spectroscopic data and the
elemental analysis, the formation of 6,7,8,9-tetrafluorodibenzo-
[b,f ][1,4]oxazepine (Ox1) is proposed.
Suitable single crystals from a THF solution of Ox1 were
obtained to be studied by X-ray diffraction techniques (Figure
4, Table 2). This study confirms the structure suggested on the
basis of the NMR and elemental analysis data. As shown in
Figure 4, the solid state structure demonstrates that, in THF
solution, compound 3a goes through a C−F ortho bond
activation that leads to the formation of a dibenzoxazepine.
Interestingly, under these conditions, this intramolecular C−F
bond cleavage occurs only from the potassium complex 3a,
while 1a and 2a remain unchanged. Dibenzoxazepines are very
interesting derivatives in medicinal chemistry due to their
biological and pharmacological activity.14 However, catalytic
asymmetric methodologies for the synthesis of chiral
dibenzoxazepines are uncommon.15
Influence of the Solvent. In order to obtain a better
understanding over the intramolecular C−F bond activation
process and to promote that the lithium 1a and sodium 2a
derivatives could also go through this C−F bond activation, a
stronger donor solvent such as DMSO was employed. Under
1
these conditions, the formation of Ox1 is detected by H and
19F NMR experiments. As such, when 1a and 2a are dissolved
in DMSO-d6, the spectra registered immediately display an
identical set of signals than the previously recorded for the
isolated crystals of Ox1 obtained from the THF solution of 3a
C
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(Figure S5 in the SI). This evidence confirms that an
intramolecular SNAr of the fluorine atom in the ortho position
for 1a and 2a takes place in the presence of dimethylsulfoxide.
As expected, when 3a was dissolved in DMSO, the Ox1
product was also formed immediately. On the basis of these
results, the reaction pathway for this SNAr reaction for the
fluoroaromatic compound {La}H mediated by different alkali
metals is proposed in Scheme 2.
Scheme 2. Proposed Reaction Pathway Based on the
Experimental Results
Figure 5. 1H-DOSY NMR spectra of complex 2a recorded in THF-d8
(see SI). The internal reference standards were N-benzylideneaniline
(PhNCHPh; FW = 181.2), 1-phenylnaphthalene (PhN, FW =
204.7), and 1,2,3,4-tetraphenylnaphthalene (TPhN, FW = 432.6).16
The reaction may start with the formation of an alkoxo-
imino alkali metal complex.10 This compound exhibits an M···
F interaction as observed in the crystalline structure of 2a. This
interaction might increase the electrophilicity of the carbon
atom, which then becomes more susceptible to the
nucleophilic attack by the oxygen atom bound to the alkali
metal. This nucleophilic attack leads to the formation of the
intramolecular cyclization product and the corresponding salt
MF. It is noteworthy that this behavior is preferably observed
for strong donor solvents such as dimethylsulfoxide or THF.
These reaction media probably have the ability of increasing
the C−F bond polarity, which may favor the subsequent
nucleophilic attack of the oxygen atom, the M−F bond
formation, and the intramolecular cyclization compound
generation.
dimeric and the monomeric derivative resulting from the
fragmentation process (Figures S6 and S7, Table S3; see
Supporting Information). When another equivalent of DMSO-
d6 is added, the NMR experiment shows again the presence of
two compounds. Now, the dimeric compound has disappeared
completely and only the monomeric is detected together with
another species that match the C−F bond activation product
(Figures S8 and S9, Table S4; see Supporting Information).
After 24 h, it is not possible to identify the signals belonging to
the initial sodium complex or the monomeric species and only
the C−F bond cleavage derivative is observed. This
experimental evidence is collected in Scheme 4.
The activation process also takes place when the reaction is
performed as one pot using THF or DMSO as solvents
(Scheme 3).
Scheme 4. Diffusion-Ordered NMR Spectroscopy
Experiments in THF-d8
a
Scheme 3. Reaction Ways and Products Based on the
a
Experimental Results
a
Conditions: (a) Complex/solvent: 1a−2a/THF. (b) Complex/
solvent: 3a/THF; (1−3)a/DMSO.
a
The presence of coordinated solvent has been omitted for clarity.
For a more in-depth investigation over this process, the
reaction between compound 2a in THF-d8 and different
amounts of DMSO-d6 at room temperature has been
investigated through a series of Diffusion-Ordered NMR
SpectroscopY (DOSY) experiments. First, the aggregation
state in solution of compound 2a (Figure 5) was studied
employing the same strategy as the one previously described in
the literature.10,16 In these conditions, complex 2a shows a
dimeric nature in THF (Figure S3, Table S1; see Supporting
Information).10a Then, 1 equiv of DMSO-d6 was added and
quickly analyzed, but no changes in the aggregation state of
this compound were noticed (Figures S4 and S5, Table S2; see
Supporting Information). However, after 72 h, a disaggregation
process is observed, and two different species are identified, the
From these results, it can be deduced that the role of the
solvent is crucial in this process, leading to the disaggregation
of the multinuclear alkali metal compound and promoting the
C−F bond activation reaction.
Fluorine Substituents Influence. Encouraged by the
obtained results when the Schiff base {La}H has been used, we
considered the introduction of a variable number of fluorine
atoms in the ring to analyze their influence on the C−F
activation reactivity. In consequence, a series of Schiff base
compounds and their alkali metal derivatives have been
synthesized and fully characterized following the same
procedure as that for {La}H and (1−3)a (see Figure 6).
D
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> C6H2F3 > C6H3F2 > C6H4F). The position of the fluorine
atoms also has an important effect on the reactivity and
modifies the reaction rates as observed for {Lc}H and {Ld}H.
For these compounds, the reaction occurs faster if both
fluorine atoms are in ortho positions than if they are placed in
ortho and meta.
We also confirmed that the metal effect is a very important
factor, following the general trend of reactivity K > Na > Li,
already reported by Diness et al.6c in the N-arylation of azoles
and indoles from unactivated monofluorobenzenes which
could be related to a higher ionic character for the potassium
compounds. Finally, for Schiff bases synthesized with a
trifluoromethyl group, such as {Lf}H or {Lg}H, the C−F
bond activation does not take place as consequence of the
different C(sp3) nature of the carbon atom.
Figure 6. (a) Fluorinated Schiff bases. (b) Alkali metal derivatives.
The C−F bond activation reaction has been studied
following the same conditions as those previously described
for 1−3a by using DMSO at room temperature. The results for
these tests are summarized in Table 3. As it can be seen, a
decreasing number of fluorine atoms in the imine ring
produces a slower C−F bond activation and the SNAr reaction,
in those cases where the process takes place,17 needs longer
reaction times to reach completion. As a result, a general
reactivity trend has been found, where perfluorinated
substrates are more reactive than less substituted ones (C6F5
CONCLUSIONS
■
In summary, we have reported a series of fluorinated Schiff
base alkali metal complexes. The five-fluorinated sodium
derivative 2a can be isolated, and its crystal molecular structure
has been determined by X-ray diffraction analysis. In the
structure, an M···F interaction is observed. In the presence of
strong donor solvents, these alkali metal compounds (M = Li,
Na, K) are able to give, at room temperature, the intra-
molecular C−F bond activation of the ortho fluor-C bond with
the corresponding formation of the cyclization product, the
6,7,8,9-tetrafluorodibenzo[b,f ][1,4]oxazepine Ox1, which was
a
Table 3. C−F Bond Formation and Cyclization Products
1
also characterized by X-ray analysis. The H-DOSY NMR
experiments of the isolated sodium complex 2a let us to detect
the disaggregation process and subsequent C−F bond cleavage
that takes place in the presence of DMSO, and to confirm its
crucial role in the process. This proof leads us to suggest a
reaction pathway where the alkali metal establishes an M···F
interaction that, in the appropriate conditions, leads to the C−
F bond activation. Subsequently, the study with different Schiff
bases containing a variable number of fluorine atoms
demonstrates that the number and position of the fluorine
atoms have an important influence in the activation of the C−
F bond. Thus, the lesser fluorine atoms are present in the ring,
the harder the reaction is. This intramolecular reaction is an
important achievement for these C−F activation processes
since the reaction takes place stoichiometrically and at room
temperature using group s metals, something which is not
usually observed.
EXPERIMENTAL SECTION
■
General Procedures. Air or water sensitive experiments were
performed under an inert atmosphere using an MBraun MB-20G
glovebox (O2 < 0.6 ppm) or standard Schlenk-line techniques (O2 < 3
ppm). An MBraun Solvent Purification System was employed to
purify solvents. Moreover, deuterated solvents were degassed by
freeze−thaw−vacuum cycles and stored in a glovebox in the presence
of molecular sieves (4 Å). Fluoroaniline compounds were purchased
from Fluorochem and used as received. 2-Hydroxybenzaldehyde and
metallic precursors were purchased from Sigma-Aldrich. Sodium
hydride was washed twice with dry hexane due to that the commercial
reagent is an oil suspension. A Bruker 400 Ultrashield (1H 400 MHz,
13C 101 MHz, 19F 376 MHz) was used to record NMR spectra. All
chemical shifts were determined using the residual signal of solvents
and were reported versus SiMe4. All the new described compounds
have been characterized by elemental analysis with a PerkinElmer
2400 CHNS/O analyzer Series II. Found values close to the
calculated values have been obtained with deviations slightly above
0.4% in some cases. The nature of the substances studied, the
a
Conditions: r.t., DMSO. Li[N(SiMe3)2], NaH, K[N(SiMe3)2].
b
c
Determined by H and 19F NMR spectroscopy. Not determined.
1
E
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instability in polar solvents necessary for the crystallization, and their
tendency to retain small amounts of solvent very difficult to eliminate
under the experimental conditions applied justify these deviations.
Synthesis of (C6F5NCHC6H4OH), {La}H. A solution of
2,3,4,5,6-pentafluoroaniline (3.863 g, 0.021 mol) and 2-hydroxyben-
zaldehyde (2.603 g, 0.021 mol) in ethanol (150 mL) was prepared.
This mixture was refluxed (100 °C) for 2 days under stirring. Later, it
was concentrated under vacuum to 100 mL, and MgSO4 was added to
dry the solution. After, it was filtered and concentrated again under
vacuum and stored at low temperature one night. A pale yellow
powder was obtained and isolated in high yield. Yield: 4.972 g, 83%.
1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 12.23 (s, 1H, OH),
8.38 (s, 1H, HCN), 7.18−7.13 (m, 1H, C6H4), 7.10−7.07 (m, 1H,
C6H4), 6.95 (m, 1H, C6H4), 6.72−6.68 (m, 1H, C6H4). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 171.3 (CN), 162.2 (C−OH),
multiplets from 142.4 to 137.0 (C−F, due to complicated 13C−19F
coupling), 135.2, 133.6, 123.9, 119.6, 119.2, 118.0 (Ar−C). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −153.1 (dd, 2F, o-F), −160.3 (t,
1F, p-F), −164.0 (m, 2F, m-F). Anal. Calcd for C13H6F5NO (287.19
g/mol): C 54.37, H 2.11, N 4.88. Found: C 54.36, H 2.00, N 5.07.
Synthesis of (2,4,6-C6H2F3NCHC6H4OH), {Lb}H. Using the
same procedure as that described for {La}H but employing 2,4,6-
trifluoroaniline (3.320 g, 0.022 mol) and 2-hydroxybenzaldehyde
(215.23 g/mol): C 72.55, H 4.68, N 6.51. Found: C 72.47, H 4.87, N
6.76.
Synthesis of (2-CF3C6H4CH2NCHC6H4OH), {Lf}H. Following
the same procedure as that described for {La}H but with 2-
(trifluoromethyl)benzylamine (3.840 g, 0.021 mol) and 2-hydrox-
1
ybenzaldehyde (2.678 g, 0.021 mol). Yield: 5.514 g, 92%. H NMR
(C6D6/THF-d8, 400 MHz, 295 K): δ 13.21 (s, 1H, OH), 7.85 (s, 1H,
HCN), 7.42 (m, 1H, ArH), 7.21 (m, 1H, ArH), 7.11−6.90 (m, 5H,
ArH), 6.70 (m, 1H, ArH), 4.59 (m, 2H, −CH2−). 13C NMR (C6D6/
THF-d8, 101 MHz, 295 K): δ 167.2 (CN), 161.9 (C−OH), 137.4,
132.8, 132.4, 132.0, 129.8 (Ar−C), 127.4 (CF3), 126.1, 123.8, 119.3,
118.8, 117.4 (Ar−C), 59.6 (−CH2−). 19F NMR (C6D6/THF-d8, 376
MHz, 295 K): δ −59.8 (s, 3F, CF3). Anal. Calcd for C15H12F3NO
(279.26 g/mol): C 64.51, H 4.33, N 5.02. Found: C 64.79, H 4.32, N
5.24.
Synthesis of (CF3CH2NCHC6H4OH), {Lg}H. As described
above for {La}H but using 2,2,2-trifluoroethylamine (2.985 g, 0.029
mol) and 2-hydroxybenzaldehyde (3.680 g, 0.029 mol). Yield: 5.231
g, 87%. 1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 12.49 (s, 1H,
OH), 7.64 (s, 1H, HCN), 7.07 (m, 1H, C6H4), 6.94−6.88 (m, 2H,
C6H4), 6.67 (m, 1H, C6H4), 3.46 (m, 2H, −CH2−). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 170.8 (CN), 161.6 (C−OH),
133.6, 132.5 (Ar−C), 126.2, 123.4 (CF3, due to complicated 13C−19F
coupling), 119.0, 118.7, 117.5 (Ar−C), 59.5 (−CH2−). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −71.5 (s, 3F, CF3). Anal. Calcd
for C9H8F3NO (203.16 g/mol): C 53.21, H 3.97, N 6.89. Found: C
53.38, H 4.15, N 6.96.
1
(2.729 g, 0.022 mol). Yield: 4.513 g, 82%. H NMR (C6D6/THF-d8,
400 MHz, 295 K): δ 12.95 (s, 1H, OH), 8.22 (s, 1H, HCN), 7.06−
7.01 (m, 2H, C6H2), 6.82 (m, 1H, C6H4), 6.60 (m, 1H, C6H4), 6.23−
6.15 (m, 2H, C6H4). 13C NMR (C6D6/THF-d8, 101 MHz, 295 K): δ
168.6 (CN), 161.9 (C−OH), multiplets from 160.9 to 154.5 (C−F,
due to complicated 13C−19F coupling), 134.0, 132.8, 122.3, 119.1,
118.8, 117.7, 100.5 (Ar−C). 19F NMR (C6D6/THF-d8, 376 MHz, 295
K): δ −111.0 (s, 1F, p-F), −120.1 (s, 2F, o-F). Anal. Calcd for
C13H8F3NO (251.21 g/mol): C 62.16, H 3.21, N 5.58. Found: C
62.34, H 3.30, N 5.71.
Synthesis of [Li(O-2-{(C6F5)NCH}C6H4)] [Li{La}] (1a). A
mixture of {La}H (0.500 g, 1.74 mmol) and Li[N{Si(CH3)3}2]
(0.300 g, 1.74 mmol) was prepared in toluene (50 mL) and stirred
one night. Then, volatile compounds and the solvent were removed
under vacuum and a white powder was obtained. The resultant solid
was washed in hexane, filtered, and dried under vacuum. Yield: 0.427
1
g, 84%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.08 (s, 1H,
Synthesis of (2,6-C6H3F2NCHC6H4OH), {Lc}H. As described
HCN), 7.19 (m, 1H, C6H4), 7.04 (m, 1H, C6H4), 6.72 (m, 1H,
C6H4), 6.43 (m, 1H, C6H4). 13C NMR (C6D6/THF-d8, 101 MHz,
295 K): δ 173.5 (CN), 172.4 (C−O), multiplets from 161.1 to
138.0 (C−F, due to complicated 13C−19F coupling), 137.4, 135.6,
129.3, 125.7, 123.5, 122.0, 113.2, 109.2 (Ar−C). 19F NMR (C6D6/
THF-d8, 376 MHz, 295 K): δ −155.1 (bs, 2F, o-F), −163.3 (bs, 1F, p-
F), −164.4 (m, 2F, m-F). Anal. Calcd for C13H5F5LiNO (293.12 g/
mol): C 53.27, H 1.72, N 4.78. Found: C 53.48, H 1.90, N 5.10.
Synthesis of [Na(O-2-{(C6F5)NCH}C6H4)] [Na{La}] (2a). As
described for 1a but using {La}H (0.500 g, 1.74 mmol) and NaH
(0.042 g, 1.74 mmol). A yellow pale powder was obtained. Yield:
0.442 g, 82%. 1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.03 (s,
1H, HCN), 6.90 (m, 2H, C6H4), 6.26 (m, 2H, C6H4). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 173.7 (CN), 171.9 (C−O),
multiplets from 141.9 to 136.1 (C−F, due to complicated 13C−19F
coupling), 136.9, 134.2, 129.7, 123.1, 122.2, 111.8 (Ar−C). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −157.3 (bs, 2F, o-F), −164.5
(m, 2F, m-F), −164.8 (m, 1F, p-F). Anal. Calcd for C13H5F5NNaO
(309.17 g/mol): C 50.50, H 1.63, N 4.53. Found: C 50.55, H 1.82, N
5.25.
Synthesis of [K(O-2-{(C6F5)NCH}C6H4)] [K{La}] (3a). As
described aboved for 1a but using {La}H (0.222 g, 0.773 mmol)
and K[N{Si(CH3)3}2] (0.162 g, 0.773 mmol). Yield: 0.221 g, 88%.
1H NMR (C6D6, 400 MHz, 295 K): δ 7.71 (s, 1H, HCN), 6.99 (s,
1H, C6H4), 6.86 (m, 1H, C6H4), 6.39 (m, 1H, C6H4), 5.22 (m, 1H,
C6H4). 13C NMR (C6D6, 101 MHz, 295 K): δ 174.0 (CN), 172.2
(C−O), multiplets from 155.3 to 137.7 (C−F, due to complicated
13C−19F coupling), 138.2, 135.6, 130.0, 123.5, 122.7, 112.0 (Ar−C).
19F NMR (C6D6, 376 MHz, 295 K): δ −158.9 (m, 2F, o-F), −163.2
above but using 2,6-difluoroaniline (3.710 g, 0.028 mol) and 2-
1
hydroxybenzaldehyde (3.474 g, 0.028 mol). Yield: 5.735 g, 88%. H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 12.92 (s, 1H, OH), 8.45
(s, 1H, HCN), 7.11 (m, 1H, C6H4), 7.02−6.95 (m, 2H, C6H4),
6.69−6.63 (m, 4H, C6H4-C6H3). 13C NMR (C6D6/THF-d8, 101
MHz, 295 K): δ 169.6 (CN), 162.2 (C−OH), multiplets from
157.5 to 154.9 (C−F, due to complicated 13C−19F coupling), 134.2,
133.2, 126.7, 126.0, 119.6, 119.2, 117.8, 112.3, 112.0 (Ar−C). 19F
NMR (C6D6/THF-d8, 376 MHz, 295 K): δ −123.7 (s, 2F, o-F). Anal.
Calcd for C13H9F2NO (233.22 g/mol): C 66.95, H 3.89, N 6.01.
Found: C 67.09, H 3.59, N 6.19.
Synthesis of (2,3-C6H3F2NCHC6H4OH), {Ld}H. As described
for {La}H but using 2,3-difluoroaniline (3.954 g, 0.030 mol) and 2-
1
hydroxybenzaldehyde (3.741 g, 0.030 mol). Yield: 5.976 g, 85%. H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 13.03 (s, 1H, OH), 7.88
(s, 1H, HCN), 7.05 (m, 2H, C6H3), 6.86 (d, 1H, C6H3), 6.65 (m,
1H, C6H4), 6.54 (m, 1H, C6H4), 6.40 (m, 1H, C6H4), 6.22 (m, 1H,
C6H4). 13C NMR (C6D6/THF-d8, 101 MHz, 295 K): δ 165.8 (C
N), 162.0 (C−OH), multiplets from 152.6 to 138.5 (C−F, due to
complicated 13C−19F coupling), 133.9, 132.7, 123.6, 119.0, 118.8,
117.7, 116.4, 114.6, 114.4 (Ar−C). 19F NMR (C6D6/THF-d8, 376
MHz, 295 K): δ −137.1 (d, 1F, o-F), −150.5 (d, 1F, m-F). Anal.
Calcd for C13H9F2NO (233.22 g/mol): C 66.95, H 3.89, N 6.01.
Found: C 66.66, H 3.85, N 6.36.
Synthesis of (2-C6H4FNCHC6H4OH), {Le}H. Using the same
method as that for {La}H but employing a mixture of 2-fluoroaniline
(3.097 g, 0.028 mol) and 2-hydroxybenzaldehyde (3.474 g, 0.028
mol). A yellow powder was isolated in high yield. Yield: 5.334 g, 89%.
1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 13.36 (s, 1H, OH),
8.02 (s, 1H, HCN), 7.06 (m, 2H, C6H4), 6.89 (m, 1H, C6H4),
6.82−6.59 (m, 5H, C6H4). 13C NMR (C6D6/THF-d8, 101 MHz, 295
K): δ 165.0 (CN), 162.3 (C−OH), 157.4, 154.9 (C−F, due to
complicated 13C−19F coupling), 136.9, 133.8, 132.8, 124.6, 121.7,
119.5, 118.9, 117.9, 116.5 (Ar−C). 19F NMR (C6D6/THF-d8, 376
MHz, 295 K): δ −125.5 (s, 1F, o-F). Anal. Calcd for C13H10FNO
(m, 2F, m-F), −164.0 (m, 1F, p-F). Anal. Calcd for C13H5F5KNO
(325.28 g/mol): C 48.00, H 1.55, N 4.31. Found: C 47.62, H 1.64, N
4.51.
Synthesis of [Li(O-2-{(2,4,6-C6H2F3)NCH}C6H4)] [Li{Lb}]
(1b). Using the same method as that described for 1a but employing
{Lb}H (0.620 g, 2.47 mmol) and Li[N{Si(CH3)3}2] (0.426 g, 2.47
mmol). Yield: 0.602 g, 95%. 1H NMR (C6D6/THF-d8, 400 MHz, 295
F
DOI: 10.1021/acs.organomet.8b00868
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
K): δ 8.22 (s, 1H, HCN), 7.17 (bs, 1H, C6H4), 7.03 (bs, 1H,
C6H4), 6.83 (m, 1H, C6H4), 6.45 (m, 1H, C6H4), 6.26 (m, 2H, C6H2).
13C NMR (C6D6/THF-d8, 101 MHz, 295 K): δ 171.8 (CN), 169.5
(C−O), multiplets from 160.5 to 154.7 (C−F, due to complicated
13C−19F coupling), 137.1, 134.5, 123.5, 122.6, 113.1, 100.6 (Ar−C).
19F NMR (C6D6/THF-d8, 376 MHz, 295 K): δ −113.5 (bs, 2F, o-F),
g, 4.29 mmol) and NaH (0.103 g, 4.29 mmol). Yield: 0.991 g, 91%.
1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.02 (s, 1H, HCN),
7.09 (m, 1H, C6H4), 6.97 (m, 1H, C6H4), 6.77 (m, 1H, C6H3), 6.55
(m, 3H, C6H4-C6H3), 6.38 (m, 1H, C6H3). 13C NMR (C6D6/THF-d8,
101 MHz, 295 K): δ 172.4 (C−O), 168.3 (CN),155.9 (Ar−C),
multiplets from 149.7 to 143.8 (C−F, due to complicated 13C−19F
coupling), 136.8, 133.8, 123.7, 123.3, 115.9, 112.2, 111.5 (Ar−C). 19F
NMR (C6D6/THF-d8, 376 MHz, 295 K): δ −138.4 (s, 1F, o-F),
−155.7 (bs, 1F, m-F). Anal. Calcd for C13H8F2NNaO (255.20 g/
mol): C 61.18, H 3.16, N 5.49. Found: C 61.40, H 3.23, N 5.55.
Synthesis of [K(O-2-{(2,3-C6H3F2)NCH}C6H4)] [K{Ld}] (3d).
As described above for compound 1a and using {Ld}H (0.600 g, 2.57
mmol) and K[N{Si(CH3)3}2] (0.540 g, 2.57 mmol). Yield: 0.663 g,
−122.2 (s, 1F, p-F). Anal. Calcd for C13H7F3LiNO (257.14 g/mol): C
60.72, H 2.74, N 5.45. Found: C 60.68, H 2.95, N 5.85.
Synthesis of [Na(O-2-{(2,4,6-C6H2F3)NCH}C6H4)] [Na{Lb}]
(2b). Following the same procedure as that described for 1a but using
{Lb}H (1.005 g, 4.00 mmol) and NaH (0.096 g, 4.00 mmol). Yield:
1
1.045 g, 96%. H NMR (C6D6/THF-d8, 400 MHz): δ 8.14 (s, 1H,
HCN), 7.02 (m, 1H, C6H4), 6.89 (m, 1H, C6H4), 6.65 (bs, 1H,
C6H4), 6.36−6.27 (m, 3H, C6H4-C6H2). 13C NMR (C6D6/THF-d8,
101 MHz, 295 K): δ 172.4 (CN), 169.1 (C−O), multiplets from
160.7 to 148.4 (C−F, due to complicated 13C−19F coupling), 136.9,
133.6, 130.5, 123.3, 111.3, 113.8, 100.1 (Ar−C). 19F NMR (C6D6/
THF-d8, 376 MHz, 295 K): δ −115.9 (bs, 1F, p-F), −125.1 (bs, 2F, o-
F). Anal. Calcd for C13H7F3NNaO (273.19 g/mol): C 57.16, H 2.58,
N 5.13. Found: C 57.55, H 2.66, N 5.19.
Synthesis of [K(O-2-{(2,4,6-C6H2F3)NCH}C6H4)] [K{Lb}]
(3b). As described for 1a but with {Lb}H (1.000 g, 3.98 mmol)
and K[N{Si(CH3)3}2] (0.836 g, 3.98 mmol). Yield: 1.017 g, 88%. 1H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.04 (s, 1H, HCN),
6.94 (m, 1H, C6H4), 6.77 (m, 1H, C6H4), 6.33 (m, 2H, C6H2), 6.19
(m, 1H, C6H4), 6.01 (m, 1H, C6H4). 13C NMR (C6D6/THF-d8, 101
MHz, 295 K): δ 174.5 (C−O), 172.9 (CN), multiplets from 159.3
to 153.9 (C−F, due to complicated 13C−19F coupling), 137.0, 133.7
(Ar−C), multiplets from 130.5 to 129.3 (C−F, due to complicated
13C−19F coupling), 123.3, 122.2, 109.7, 100.5 (Ar−C). 19F NMR
1
95%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.13 (s, 1H,
HCN), 7.14 (m, 1H, C6H3), 6.69−6.54 (m, 5H, C6H4-C6H3), 6.29
(m, 1H, C6H4). 13C NMR (C6D6/THF-d8, 101 MHz, 295 K): δ 174.3
(C−O), 168.2 (CN), multiplets from 152.6 to 143.3 (C−F, due to
complicated 13C−19F coupling), 137.0, 134.1, 124.3, 123.8, 123.1,
116.6, 112.1, 111.9, 110.4 (Ar−C). 19F NMR (C6D6/THF-d8, 376
MHz, 295 K): δ −139.2 (d, 1F, o-F), −154.5 (d, 1F, m-F). Anal.
Calcd for C13H8F2KNO (271.31 g/mol): C 57.55, H 2.97, N 5.16.
Found: C 57.22, H 3.14, N 5.08.
Synthesis of [Li(O-2-{(2-C6H4F)NCH}C6H4)] [Li{Le}] (1e).
The same procedure as that described for 1a was followed but with
{Le}H (1.000 g, 4.65 mmol) and Li[N{Si(CH3)3}2] (0.801 g, 4.65
mmol). Yield: 0.920 g, 90%. 1H NMR (C6D6/THF-d8, 400 MHz, 295
K): δ 8.27 (s, 1H, HCN), 7.19 (m, 1H, C6H4), 7.14 (bs, 1H,
C6H4), 6.95−6.76 (m, 5H, C6H4), 6.45 (t, 1H, C6H4). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 171.9 (C−O), 167.0 (CN),
multiplets from 157.9 to 155.4 (C−F, due to complicated 13C−19F
coupling), 140.8, 136.8, 134.2, 125.8, 124.8, 123.8, 122.9, 121.2,
115.9, 112.5 (Ar−C). 19F NMR (C6D6/THF-d8, 376 MHz, 295 K): δ
−127.8 (s, 1F, o-F). Anal. Calcd for C13H9FLiNO (221.16 g/mol): C
70.60, H 4.10, N 6.33. Found: C 70.24, H 4.24, N 6.44.
(C6D6/THF-d8, 376 MHz, 295 K): δ −117.2 (s, 1F, p-F), −126.3 (s,
2F, o-F). Anal. Calcd for C13H7F3KNO (289.30 g/mol): C 53.97, H
2.44, N 4.84. Found: C 54.22, H 2.81, N 4.93.
Synthesis of [Li(O-2-{(2,6-C6H3F2)NCH}C6H4)] [Li{Lc}] (1c).
As described for 1a but using {Lc}H (0.390 g, 1.67 mmol) and
Synthesis of [Na(O-2-{(2-C6H4F)NCH}C6H4)] [Na{Le}] (2e).
As described for 1a but using {Le}H (1.000 g, 4.64 mmol) and NaH
(0.111 g, 4.64 mmol). A yellow powder was obtained. Yield: 0.946 g,
1
Li[N{Si(CH3)3}2] (0.288 g, 1.67 mmol). Yield: 0.325 g, 81%. H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.40 (bs, 1H, HCN),
6.94 (m, 3H, C6H4-C6H3), 6.37−6.27 (m, 4H, C6H4-C6H3). 13C
NMR (C6D6/THF-d8, 101 MHz, 295 K): δ 171.5 (CN), 169.3
(C−O), multiplets from 157.7 to 155.2 (C−F, due to complicated
13C−19F coupling), 137.0, 134.4, 124.6, 123.6, 123.1, 114.5, 112.0,
111.8 (Ar−C). 19F NMR (C6D6/THF-d8, 376 MHz, 295 K): δ
−125.4 (s, 2F, o-F). Anal. Calcd for C13H8F2LiNO (239.15 g/mol): C
65.29, H 3.37, N 5.86. Found: C 65.42, H 3.63, N 5.97.
1
86%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.03 (s, 1H,
HCN), 7.11 (m, 1H, C6H4), 6.93 (m, 2H, C6H4), 6.70 (m, 4H,
C6H4), 6.42 (bs, 1H, C6H4). 13C NMR (C6D6/THF-d8, 101 MHz,
295 K): δ 166.7 (CN), 157.5 (C−O), multiplets from 150.1 to
149.2 (C−F, due to complicated 13C−19F coupling), 137.2, 133.7,
133.3, 125.1, 124.3, 123.6, 119.9, 115.5, 110.9 (Ar−C). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −132.2 (s, 1F, o-F). Anal. Calcd
for C13H9FNNaO (237.21 g/mol): C 65.83, H 3.82, N 5.90. Found:
C 65.78, H 3.56, N 5.80.
Synthesis of [K(O-2-{(2-C6H4F)NCH}C6H4)] [K{Le}] (3e). As
described for 1a but using {Le}H (1.000 g, 4.64 mmol) and
K[N{Si(CH3)3}2] (0.976 g, 4.64 mmol). Yield: 0.917 g, 80%. 1H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.09 (s, 1H, HCN),
7.12 (m, 1H, C6H4), 6.97 (m, 1H, C6H4), 6.86−6.72 (m, 4H, C6H4),
6.54 (m, 1H, C6H4), 6.26 (m, 1H, C6H4). 13C NMR (C6D6/THF-d8,
101 MHz, 295 K): δ 174.3 (C−O), 167.5 (CN), multiplets from
157.6 to 155.2 (C−F, due to complicated 13C−19F coupling), 143.3,
137.1, 133.9, 125.0, 124.7, 124.1, 123.4, 121.4, 115.6, 110.1 (Ar−C).
19F NMR (C6D6/THF-d8, 376 MHz, 295 K): δ −128.8 (s, 1F, o-F).
Synthesis of [K(O-2-{(2,6-C6H3F2)NCH}C6H4)] [K{Lc}] (3c).
Using the same procedure but employing {Lc}H (0.400 g, 1.72
mmol) and K[N{Si(CH3)3}2] (0.360 g, 1.72 mmol). Yield: 0.407 g,
1
88%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.14 (s, 1H,
HCN), 6.99 (m, 1H, C6H4), 6.82 (m, 1H, C6H4), 6.55−6.43 (m,
3H, C6H3-C6H4), 6.19 (m, 2H, C6H3). 13C NMR (C6D6/THF-d8, 101
MHz, 295 K): δ 174.9 (C−O), 172.3 (CN), multiplets from 157.0
to 154.5 (C−F, due to complicated 13C−19F coupling), 137.0, 133.8,
123.0, 122.6, 111.9, 111.5, 109.8 (Ar−C). 19F NMR (C6D6/THF-d8,
376 MHz, 295 K): δ −143.1 (s, 2F, o-F). Anal. Calcd for
C13H8F2KNO (271.31 g/mol): C 57.55, H 2.97, N 5.16. Found: C
57.83, H 2.76, N 5.03.
Synthesis of [Li(O-2-{(2,3-C6H3F2)NCH}C6H4)] [Li{Ld}] (1d).
Using the same method as that for 1a but with {Ld}H (0.390 g, 1.67
mmol) and Li[N{Si(CH3)3}2] (0.288 g, 1.67 mmol). Yield: 0.305 g,
Anal. Calcd for C13H9FKNO (253.32 g/mol): C 61.64, H 3.58, N
5.53. Found: C 61.28, H 3.61, N 5.57.
1
Synthesis of [Li(O-2-{(2-CF3C6H4CH2)NCH}C6H4)] [Li{Lf}]
(1f). Using the same method as that for 1a but with {Lf}H (0.684
g, 2.45 mmol) and Li[N{Si(CH3)3}2] (0.423 g, 2.45 mmol). Yield:
0.583 g, 83%. 1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 7.97 (s,
1H, HCN), 7.42−7.37 (m, 2H, ArH), 7.10−6.89 (m, 4H, ArH),
6.43 (bs, 2H, ArH), 4.57 (bs, 2H, −CH2−). 13C NMR (C6D6/THF-
d8, 101 MHz, 295 K): δ 169.1 (CN), 163.8 (C−O), 138.5, 136.0,
133.0, 132.5, 131.2 (Ar−C), 126.9 (CF3), 125.6, 124.0, 122.8, 112.2
(Ar−C), 62.1 (−CH2−). 19F NMR (C6D6/THF-d8, 376 MHz, 295
K): δ −59.4 (s, 3F, CF3). Anal. Calcd for C15H11F3LiNO (285.19 g/
mol): C 63.17, H 3.89, N 4.91. Found: C 63.41, H 3.92, N 4.67.
76%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.14 (s, 1H,
HCN), 7.21 (m, 1H, C6H4), 7.12 (d, 1H, C6H4), 6.93 (d, 1H,
C6H4), 6.63−6.46 (m, 4H, C6H4-C6H3). 13C NMR (C6D6/THF-d8,
101 MHz, 295 K): δ 172.0 (C−O), 168.3 (CN), multiplets from
152.8 to 143.4 (C−F, due to complicated 13C−19F coupling), 142.9,
137.0, 134.7, 123.9, 123.7, 122.6, 116.7, 113.0, 112.9 (Ar−C). 19F
NMR (C6D6/THF-d8, 376 MHz, 295 K): δ −138.5 (d, 1F, o-F),
−153.1 (d, 1F, m-F). Anal. Calcd for C13H8F2LiNO (239.15 g/mol):
C 65.29, H 3.37, N 5.86. Found: C 65.27, H 3.77, N 6.28.
Synthesis of [Na(O-2-{(2,3-C6H3F2)NCH}C6H4)] [Na{Ld}]
(2d). Using the same method as that for 1a but with {Ld}H (1.000
G
DOI: 10.1021/acs.organomet.8b00868
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Synthesis of [K(O-2-{(2-CF3C6H4CH2)NCH}C6H4)] [K{Lf}]
(3f). As described for 1a but with {Lf}H (0.502 g, 1.80 mmol) and
K[N{Si(CH3)3}2] (0.378 g, 1.80 mmol). Yield: 0.386 g, 68%. 1H
NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 8.20 (s, 1H, HCN),
7.41 (m, 2H, C6H4), 7.22 (bs, 1H, C6H4), 7.05−6.92 (m, 3H, C6H4),
Synthesis of 9-Fluorodibenz[b,f][1,4]oxazepine (Ox3). At
room temperature, a mixture of {Lc}H (0.400 g, 1.72 mmol) and
K[N{Si(CH3)3}2] (0.360 g, 1.72 mmol) in toluene (50 mL) was
stirred for one night. Then, the complex was isolated under vacuum,
and a little quantity of DMSO was added. After the reaction time, 5
mL of hexane was added. However, this compound is completely
soluble in any solvent. In consequence, it was directly dried under
6.54 (bs, 1H, C6H4), 6.38 (m, 1H, C6H4), 4.69 (bs, 2H, −CH2−). 13
C
NMR (C6D6/THF-d8, 101 MHz, 295 K): δ 168.2 (CN), 164.6
(C−O), 139.7, 135.2, 133.0, 132.7, 130.5, 129.5(Ar−C), 127.0 (CF3),
126.0, 124.0, 123.2, 121.8, 111.2 (Ar−C), 62.4 (−CH2−). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −59.6 (s, 3F, CF3). Anal. Calcd
for C15H11F3KNO (317.04 g/mol): C 56.77, H 3.49, N 4.41. Found:
C 56.39, H 3.65, N 4.58.
Synthesis of [Li(O-2-{(CF3CH2)NCH}C6H4)] [Li{Lg}] (1g).
Using the same method as that for 1a but with {Lg}H (0.486 g,
2.39 mmol) and Li[N{Si(CH3)3}2] (0.412 g, 2.39 mmol). Yield:
0.410 g, 82%. 1H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 7.86 (s,
1H, HCN), 7.14 (m, 1H, C6H4), 7.02 (d, 1H, C6H4), 6.76 (d, 1H,
C6H4), 6.42 (m, 1H, C6H4), 3.62 (m, 2H, −CH2−). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 172.9 (CN), 171.0 (C−O),
136.3, 134.0 (Ar−C), 127.0, 124.3 (CF3, due to complicated 13C−19F
coupling), 123.3, 121.9, 112.3 (Ar−C), 62.2 (−CH2−). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −71.2 (s, 3F, CF3). Anal. Calcd
for C9H7F3LiNO (209.10 g/mol): C 51.70, H 3.37, N 6.70. Found: C
51.40, H 3.52, N 6.51.
1
vacuum. Yield: 0.329 g, 90%. H NMR (C6D6/DMSO-d6, 400 MHz,
295 K): δ 8.54 (s, 1H, HCN), 7.28 (m, 2H, C6H4), 7.02 (m, 3H,
C6H4-C6H3), 6.86 (m, 2H, C6H4-C6H3). 13C NMR (C6D6/DMSO-d6,
101 MHz, 295 K): δ 162.3 (CN), 160.0 (C−O, C6H4), 159.2 (C−
O, C6H3), 156.7, 154.4 (C−F, due to complicated 13C−19F coupling),
134.2, 130.8, 129.2, 127.6, 125.9, 120.9, 117.2, 113.4, 113.2 (Ar−
C).19F NMR (C6D6/DMSO-d6, 376 MHz, 295 K): δ −119.6 (s, 1F,
C6H3F). Anal. Calcd for C13H8FNO (213.21 g/mol): C 73.23, H
3.78, N 6.57. Found: C 73.69, H 3.67, N 6.79.
Synthesis of 6-Fluorodibenz[b,f ][1,4]oxazepine (Ox4). As
described aboved but employing {Ld}H (0.400 g, 1.72 mmol) and
K[N{Si(CH3)3}2] (0.360 g, 1.72 mmol). 1H NMR (C6D6/DMSO-d6,
400 MHz, 295 K): δ 8.51 (s, 1H, HCN), 7.30 (m, 2H, ArH), 7.05−
6.96 (m, 5H, ArH). 13C NMR (C6D6/DMSO-d6, 101 MHz, 295 K): δ
161.9 (CN), 160.0 (C−O), 155.3, 152.8 (C−F, due to complicated
13C−19F coupling), 142.9 (C−O), 134.2, 131.1, 127.5, 126.1, 125.7,
124.3, 120.8, 115.6, 115.4 (Ar−C).19F NMR (C6D6/DMSO-d6, 376
MHz, 295 K): δ −133.1 (s, 1F, C6H3F). Anal. Calcd for C13H8FNO
(213.21 g/mol): C 73.23, H 3.78, N 6.57. Found: C 73.04, H 3.65, N
6.19.
Synthesis of [K(O-2-{(CF3CH2)NCH}C6H4)] [K{Lg}] (3g). As
described above for compound 1a and using {Lg}H (0.421 g, 2.07
mmol) and K[N{Si(CH3)3}2] (0.435 g, 2.07 mmol). Yield: 0.266 g,
Single-Crystal X-ray Structure Determination for (2a·2THF)
and Ox1. Data collection was performed at 200(2) K, with the
crystals covered with perfluorinated ether oil. Single crystals of 1c
were mounted on a Bruker-Nonius Kappa CCD single-crystal
diffractometer equipped with a graphite-monochromated Mo−Kα
radiation (λ = 0.71073 Å). Multiscan18 absorption correction
procedures were applied to the data. The structure was solved using
the WINGX package,19 by direct methods (SHELXS-97) and refined
using full-matrix least-squares against F2 (SHELXL-16).20 All non-
hydrogen atoms were anisotropically refined. Hydrogen atoms were
geometrically placed and left riding on their parent atoms except for
H7 in Ox1 that was found in the Fourier map and refined freely. As
well, Ox1 showed some degree of twinning. For 2a, two disordered
solvent molecules were present per each molecule of compound 2a.
No chemical sense could be done of the disordered solvent molecule,
so the squeeze procedure21 was applied to remove its contribution
from the structure factors. As well, there is some disorder in the THF
molecules bonded to the Na, that was not treated. Full-matrix least-
1
53%. H NMR (C6D6/THF-d8, 400 MHz, 295 K): δ 7.92 (s, 1H,
HCN), 7.10 (m, 1H, C6H4), 7.02 (m, 1H, C6H4), 6.90 (m, 1H,
C6H4), 6.66 (m, 1H, C6H4), 3.68 (m, 2H, −CH2−). 13C NMR
(C6D6/THF-d8, 101 MHz, 295 K): δ 171.1 (C−O), 168.9 (CN),
133.6, 132.5 (Ar−C), 126.5, 123.7 (CF3, due to complicated 13C−19F
coupling), 119.0, 118.7, 117.8 (Ar−C), 59.7 (−CH2−). 19F NMR
(C6D6/THF-d8, 376 MHz, 295 K): δ −71.7 (s, 3F, CF3). Anal. Calcd
for C9H7F3KNO (241.25 g/mol): C 44.81, H 2.92, N 5.81. Found: C
44.35, H 2.87, N 6.16.
Synthesis of 6,7,8,9-Tetrafluorodibenz[b,f ][1,4]oxazepine
(Ox1). At room temperature, a mixture of {La}H (0.530 g, 1.84
mmol) and K[N{Si(CH3)3}2] (0.387 g, 1.84 mmol) in toluene (50
mL) was stirred for one night. Volatile compounds were removed
under vacuum, and the resultant solution was filtered and
concentrated under reduced pressure and cooled at −20 °C, giving
a yellow powder. This solid was filtered and dried under vacuum.
Later, a little amount of THF or DMSO was added. A dark red
solution was formed, and one single crystal was finally obtained and
2
squares refinements were carried out by minimizing ∑w(Fo − Fc2)2
1
analyzed by X-ray diffraction. Yield: 0.440 g, 89%. H NMR (C6D6/
with the SHELXL-97 weighting scheme and stopped at shift/err <
0.001. The final residual electron density maps showed no remarkable
features. Crystallographic data for the structures reported in this paper
have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication nos. CCDC- 1881295 (2a·
2THF) and CCDC-1881296 (Ox1).
DMSO-d6, 400 MHz, 295 K): δ 8.59 (s, 1H, HCN), 7.34 (m, 2H,
C6H4), 7.10 (m, 1H, C6H4), 7.01 (m, 1H, C6H4). 13C NMR (C6D6/
DMSO-d6, 101 MHz, 295 K): δ 164.1 (CN), 159.3 (C−O),
multiplets from 143.7 to 137.1 (C−F, due to complicated 13C−19F
coupling), 141.0, 134.9, 131.5, 127.2, 126.8, 121.0 (Ar−C). 19F NMR
(C6D6/DMSO-d6, 376 MHz, 295 K): δ −148.4 (dd, 1F, C6F4),
−158.7 (t, 1F, C6F4), −159.7 (dd, 1F, C6F4), −163.1 (t, 1F, C6F4).
Anal. Calcd for C13H5F4NO (267.18 g/mol): C 58.44, H 1.89, N
5.24. Found: C 58.35, H 1.75, N 5.35.
ASSOCIATED CONTENT
■
S
* Supporting Information
Synthesis of 7,9-Difluorodibenz[b,f ][1,4]oxazepine (Ox2).
Following the same procedure as that described above but using
{Lb}H (0.500 g, 1.99 mmol) and K[N{Si(CH3)3}2] (0.418 g, 1.99
mmol). After the addition of DMSO, 10 mL of hexane was added, and
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00868.
1
a dark yellow solid could be isolated. Yield: 0.391 g, 85%. H NMR
Characterization data for the synthesized compounds,
details for the solid state structure determination, and
NMR spectra (PDF)
(C6D6/DMSO-d6, 400 MHz, 295 K): δ 8.48 (s, 1H, HCN), 7.25
(m, 2H, C6H4), 7.01 (m, 2H, C6H4), 6.76 (m, 2H, C6H2). 13C NMR
(C6D6/DMSO-d6, 101 MHz, 295 K): δ 161.7 (CN), 159.4 (C−O),
multiplets from 163.3 to 156.7 (C−F, due to complicated 13C−19F
coupling), 154.5, 134.2, 130.9, 127.4, 127.2, 126.2, 121.0, 105.2, 102.1
(Ar−C). 19F NMR (C6D6/DMSO-d6, 376 MHz, 295 K): δ −110.6 (d,
1F, C6H2F2), −115.4 (d, 1F, C6H2F2). Anal. Calcd for C13H7F2NO
(231.20 g/mol): C 67.54, H 3.05, N 6.06. Found: C 67.23, H 2.81, N
6.11.
Accession Codes
CCDC 1881295 and 1881296 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
H
DOI: 10.1021/acs.organomet.8b00868
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
F Bond Activation in Organic Synthesis. Chem. Rev. 2009, 109, 2119−
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Functionalization of Fluorinated Molecules by Transition-Metal-
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Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
■
Corresponding Authors
*E-mail: jesus.cano@uah.es (J.C.).
*E-mail: martaeg.mosquera@uah.es (M.E.G.M.).
(4) (a) Giffin, K. A.; Korobkov, I.; Baker, R. T. Bronsted acid-
promoted C-F bond activation in [P,S]-ligated neutral and anionic
perfluoronickelacyclopentanes. Dalton Trans. 2015, 44, 19587−
19596. (b) Chen, W.; Bakewell, C.; Crimmin, M. R. Functionalisation
of Carbon-Fluorine Bonds with Main Group Reagents. Synthesis
2017, 49, 810−821. (c) Huang, W.; Diaconescu, P. L. Aromatic C−F
Bond Activation by Rare-Earth-Metal Complexes. Organometallics
2017, 36, 89−96. (d) Deacon, G. B.; Forsyth, C. M.; Junk, P. C.;
Wang, J. Intramolecular Metal-Fluorocarbon Coordination, C-F Bond
Activation and Lanthanoid-Fluoride Clusters with Tethered Poly-
fluorophenylamide Ligands. Chem. - Eur. J. 2009, 15, 3082−3092.
ORCID
́
Jesus Cano: 0000-0002-6643-7534
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Dedicated to Prof. Dietmar Stalke on the occasion of his 60th
birthday. We acknowledge MICINN (I3 program SPI1752-
XV0), UAH (CCG08-UAH/PPQ-4203 and UAH-AE-2017-
2), and MINECO (CTQ201458270-R) projects for financial
support. EU COST Action CA15106 (CHAOS). F.M.G-V.
acknowledges the UAH for a fellowship.
́
(e) Nova, A.; Mas-Balleste, R.; Ujaque, G.; Gonzalez-Duarte, P.;
3
́
Lledos, A. Csp -F bond activation by nucleophilic attack of the
{Pt2S2} core assisted by non-covalent interactions. Chem. Commun.
2008, 3130−3132. (f) Clot, E.; Eisenstein, O.; Jasim, N.; MacGregor,
S. A.; McGrady, J. E.; Perutz, R. N. C-F and C-H Bond Activation of
Fluorobenzenes and Fluoropyridines at Transition Metal Centers:
How Fluorine Tips the Scales. Acc. Chem. Res. 2011, 44, 333−348.
(g) Cano, J.; Sudupe, M.; Royo, P.; Mosquera, M. E. G. Evidence of
Fluoride Transfer from the Anion of [Zr{C5H3[SiMe2(η1-
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Richmond, T. G.; Osterberg, C. E. Activation of Carbon-Fluorine
Bonds by Metal Complexes. Chem. Rev. 1994, 94, 373−431.
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