Synthesis, Characterization, and Electronic Properties of Porphyrins Conjugated with N-Heterocyclic Carbene (NHC)-Gold(I) Complexes

Article abstract of DOI:10.1021/acs.organomet.5b00966

Porphyrins fused to peripheral N-heterocyclic carbenes (NHC) across two neighboring β,β-pyrrolic positions were used for the synthesis of different mono- and bis-carbenic gold(I) complexes. These studies also revealed how it is possible to modulate the re

Full text of DOI:10.1021/acs.organomet.5b00966

Article
pubs.acs.org/Organometallics
Synthesis, Characterization, and Electronic Properties of Porphyrins
Conjugated with N‑Heterocyclic Carbene (NHC)−Gold(I) Complexes
†
‡
‡
§
†
Jean-Franco
́ ́
̧ is Longevial, Adam Langlois, Antoine Buisson, Charles H. Devillers, Sebastien Clement,
∥
‡
,†
Arie van der Lee, Pierre D. Harvey, and Seb
́
astien Richeter*
†Institut Charles Gerhardt de Montpellier ICGM, UMR 5253 CNRS-ENSCM-UM, CC 1701, Place E. Bataillon, 34095 Montpellier
Cedex 05, France
‡
Dep
́
artement de Chimie, Universite
́
de Sherbrooke, Sherbrooke, Queb
21000 Dijon, France
́
n des Membranes, UMR 5635 CNRS-ENSCM-UM, CC 047, Place E. Bataillon, 34095 Montpellier Cedex 05,
́
ec J1K 2R1, Canada
§
ICMUB, UMR CNRS 6302, Bourgogne Franche-Comte,
́
∥
Institut Europee
France
*
S Supporting Information
ABSTRACT: Porphyrins fused to peripheral N-heterocyclic carbenes (NHC) across two neighboring β,β-pyrrolic positions
were used for the synthesis of different mono- and bis-carbenic gold(I) complexes. These studies also revealed how it is possible
to modulate the reactivity of the peripheral NHC by deprotonating the inner NH groups of the fused free base porphyrin core.
All complexes were fully characterized and displayed high stability, allowing the formation of mono-carbenic and also stable
homoleptic and heteroleptic bis-carbenic Au(I) complexes. Optical and electrochemical properties of bis-carbenic Au(I) revealed
no or weak electronic communication between the porphyrins, which behave as two independent groups.
INTRODUCTION
In recent years, hybrid compounds containing NHC ligands
attached to porphyrin derivatives have been developed.
■
11−17
N-heterocyclic carbenes (NHCs) have evolved as one of the
Reported porphyrin−NHC systems differ in the position of the
NHC (Chart 1). By taking advantage of the flexibility of the
“N-confused porphyrins” (NCP, where the positions of one
most important class of ligands in the field of organometallic
1
chemistry, exhibiting broad applications in catalysis, bio-
2
,3
4,5
medicine, and materials science. Most NHCs are built
upon five-membered imidazoles or benzimidazoles and can be
easily generated by deprotonating the corresponding azolium
salts. These NHCs are considered as highly versatile ligands
because their steric and electronic properties can be quite easily
modulated according to the nature of their substituents. While
their steric properties can be varied according to the size, the
shape, and the rigidity of the substituents on the carbene
Chart 1. Porphyrin−NHC Systems Recently Reported in the
Literature
6
ligand, the variation of their electronic properties can be
achieved by grafting chemical functions onto the backbone with
7
the desired electron-donating or -accepting characters. For
NHCs with identical or at least very similar steric features, the
tuning of their electronic properties is of crucial importance for
1
catalytic applications. With regard to facile modulation of the
electronic and catalytic properties of their metal complexes,
some original NHCs with stimuli-responsive functional groups
8
9
10
(
redox, pH, or light ) may be used to allow reversible and
Received: November 22, 2015
controlled switching of their electronic properties.
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.5b00966
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Article
pyrrolic NH and one β-CH are switched), Furuta and co-
workers reported an NHC embedded in a NCP framework
1
1
(
Chart 1, A). This unique structure was serendipitously
obtained from the reaction of an inner-methylated NCP with
Re (CO) and represents a rare example of an NHC located in
2
10
18
the inner core of a macrocycle.
More examples of porphyrins with NHCs linked at their
periphery are known in the literature. Wang and co-workers
used tetraimidazolium salts as NHC precursors, and
imidazoliums were separated from the meso positions by
1
2
−
(C H )O(CH ) − spacers (Chart 1, B). Recently, Ruppert
6
5
2 3
and co-workers avoided the use of spacers by introducing azoles
1
3
directly onto meso positions. The alkylation of these
compounds afforded porphyrins with meso azolium units,
which could further be deprotonated to obtain the correspond-
ing NHC ligands and their metal complexes (Chart 1, C). In
our group, we have synthesized porphyrins fused to imidazole
and imidazolium units across two neighboring β,β-pyrrolic
Figure 1. ORTEP views of the molecular structure of the imidazolium
salt Fb-I with atomic displacement parameters at the 50% probability
level: (left) front view; (right) side view, meso aryl groups omitted for
clarity. Hydrogen atoms, except that involved in hydrogen bonding,
are omitted for clarity.
1
4
positions. The deprotonation of the imidazolium ring affords
the corresponding NHC (Chart 1, D). It is worth noting that
we showed that the electronic properties of peripheral NHC
ligands fused to free-base porphyrins can be dramatically
altered upon protonation of the inner nitrogen atoms of the
is found to be ruffled even in the absence of an inner nickel(II)
ion. The imidazolium ring and its fused pyrrole are close to
coplanarity with an angle of 10.3° between the two mean planes
calculated for each ring. It is also noticeable that the iodide is
hydrogen bonded to the C(2)−H of the imidazolium ring with
1
5
porphyrin core. So far, we have reported the synthesis of
1
5,16
17
NHC−Rh(I)
and NHC−Pd(II) complexes. Here, we
d
= 2.84 Å.
H−I
extend our investigations to the synthesis of several Au(I)
complexes and also highlight (i) how the porphyrin backbone is
able to modulate the coordination properties of the peripheral
NHC ligand and (ii) the impact of the peripheral Au(I)
complex on the photophysical properties of the porphyrins.
The synthesis of [(NHC)AuCl] complexes was achieved
following different procedures. First, the well-known prelimi-
nary formation of NHC−silver complexes was performed with
Ag O followed by transmetalation reactions with [AuCl-
2
(
THT)] (THT = tetrahydrothiophene). This synthesis strategy
allowed the synthesis of [NiAuCl] in 50% yield (Scheme 1,
RESULTS AND DISCUSSION
procedure A). The formation of the peripheral [AuCl] complex
■
1
was confirmed by H NMR spectroscopy because the signal
Synthesis and Characterization. Free base porphyrins
arising from the imidazolium proton at δ 11.07 ppm
disappeared due to the formation of the C(2)−Au bond.
Moreover, the signal of the carbene C(2) could be clearly
observed at δ 182.3 ppm in its 13C{ H} NMR spectrum and is
Fb-I and Fb-BF and their corresponding nickel(II) complexes
4
14a
Ni- I and Ni-BF were used as starting materials (Scheme 1).
4
These species are porphyrins fused to imidazolium salts across
two neighboring β-pyrrolic positions. Single crystals of Fb- I
were obtained by slow diffusion of n-pentane in a solution of
Fb-I in CH Cl . An X-ray diffraction analysis unambiguously
1
in good agreement with data reported in the literature for
3
[
(NHC)AuCl] complexes. However, the same synthetic
2
2
approach proved to be unsuccessful in obtaining the desired
complex [FbAuCl]. We presume that the silver ion could be
trapped by the free base porphyrin core, thus preventing the
established its structure (Figure 1). Notably, the porphyrin core
Scheme 1. Synthesis of [NiAuCl] and [FbAuCl] Complexes
19
formation of the NHC−Ag bond. Indeed, alternative silver-
free synthetic procedures were then sought. Recently, Nolan,
Gimeno, and their co-workers reported improved one-step
20
procedures to obtain [(NHC)AuCl] complexes. They consist
of in situ formation of the NHCs by deprotonating the
corresponding azolium salts with a weak base such as K CO in
2
3
the presence of [AuCl(SMe )]. We performed this reaction
2
with Fb-I as the NHC precursor and obtained a mixture of
[FbAuI] (major compound) and [FbAuCl] (minor com-
pound) complexes according to mass spectrometry. Then, Fb-
BF was used as an NHC precursor to prevent the formation of
4
[
FbAuI]. In this case, K CO was not strong enough to
2 3
deprotonate the imidazolium ring, because Fb-BF could be
4
recovered. Knowing that, we used KOtBu as a stronger base
(
Scheme 1, procedure B), and by reacting Fb-BF with 1.1
4
equiv of KOtBu and [AuCl(THT)] in THF at 35 °C, the
corresponding complex [FbAuCl] was obtained in a moderate
yield of 38%. All spectroscopic data are in agreement with the
proposed structure for [FbAuCl]. A broad signal at δ −2.95
ppm corresponding to the two inner NHs of the free base
1
porphyrin was observed in its H NMR spectrum. The signal of
B
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Article
the carbene was also observed at δ 182.0 ppm in its 13C{ H}
NMR spectrum. By use of the same synthetic strategy, the
complex [NiAuCl] was obtained in 34% yield. Although the
yields obtained in both cases by procedure B were rather low,
the formation of undesired side products was not observed and
the remaining starting materials Fb-BF and Ni-BF could be
1
found in the literature.22−24 Notably, Nolan and co-workers
reported the use of Au hydroxide complexes [(NHC)Au(OH)]
as precursors to obtain heteroleptic cationic complexes
a
b
+
[(NHC )Au(NHC )] by protonolysis with the appropriate
22
imidazolium salts. Recently, Cazin and co-workers reported a
straightforward route permitting the formation of heteroleptic
4
4
a
b
+
recovered after purification by column chromatography.
[(NHC )Au(NHC )] complexes under microwave irradiation
with imidazolium salts, [(NHC)AuCl] complexes, and NaOH
+
Cationic bis-carbenic [(NHC)Au(NHC)] complexes were
then obtained by reacting the aforementioned [(NHC)AuCl]
complexes with another 1 equiv of NHC generated in situ
23
as reagents. In the present study, we used the same conditions
to synthesize homoleptic and heteroleptic complexes. The
(
Scheme 2). Ni-BF and Fb-BF were used as NHC precursors
heteroleptic complex [NiAuFb]BF was obtained in 75% yield
4
4
4
by reacting the complex [NiAuCl] with 1 equiv of imidazolium
Scheme 2. Synthesis of [NiAuNi]BF , [FbAuFb]BF , and
salt Fb-BF in the presence of potassium carbonate in acetone
(Scheme 2). Spectroscopic data are in accordance with the
4
4
4
[
NiAuFb]BF Complexes
4
proposed structure for [NiAuFb]BF . Two sets of signals
4
corresponding respectively to the Ni and free base porphyrins
1
13
1
were observed in the H and C{ H} NMR spectra, including
the two signals of the carbenes at δ 194.7 and 194.2 ppm in its
13
1
C{ H} NMR spectrum (Figure S33 in the Supporting
Information). The molecular peak corresponding to the
+
cationic species [NiAuFb] was observed at m/z = 2065.9 by
MALDI-TOF mass spectrometry (Figure S34 in the Supporting
Information). EDX analyses of [NiAuFb]BF4 showed a
chemical composition of Ni/Au/Cl in a ca. 1/1/0 ratio
consistent with the proposed structure.
In the course of these studies, we observed a strong
modulation of the coordination properties of the peripheral
NHC ligand upon deprotonating the inner NH. Complex
[
1
FbAuCl] was obtained in a moderate yield of 38% when using
.1 equiv of KOtBu as base (Scheme 1, procedure B). Under
these conditions, the color of the reaction mixture remained
purple, indicating that the inner NHs of the porphyrin free base
were not deprotonated. However, the reaction mixture turned
green when using 3.3 equiv of KOtBu as the deprotonation of
the inner NH of the porphyrin takes place, followed by the
formation of the NHC. The appearance of negative charges in
the inner core of the porphyrin has dramatic effects on the
reactivity of the peripheral NHC. Indeed, bis-carbenic
2
1
and deprotonated in situ by K CO in acetone. The
2
3
homoleptic complexes [NiAuNi]BF and [FbAuFb]BF were
4
4
obtained following this procedure in 77 and 78% yields,
respectively. MALDI-TOF mass spectrometry provided evi-
dence for the formation of these homoleptic bis(NHC)−Au
complexes. The molecular peaks corresponding to the cationic
species [NiAuNi]+ and [FbAuFb]+ were observed at m/z
[FbAuFb]BF and monocarbenic [FbAuCl] complexes were
4
obtained in 82% and 9% yields, respectively (molar ratio bis/
mono ∼80/20, Scheme 3). Surprisingly, the bis-carbenic
complex [FbAuFb]BF was obtained as the major compound
4
despite the use of 1 equiv of [AuCl(THT)]. Presumably, the
2
121.7 and 2010.0, respectively (Figures S17 and S25 in the
1
13
1
Supporting Information). The H and C{ H} NMR spectra
of these complexes showed the expected signals. For examples,
the 13C{ H} NMR signals of the carbenes were observed at
Scheme 3. Reactivity of Fb-BF and Ni-BF toward 1 equiv of
4
4
[AuCl(THT)] with 3.3 equiv of KOtBu
1
1
93.9 and 194.5 ppm, respectively, for [NiAuNi]BF4 and
[
FbAuFb]BF4 (Figures S16 and S23 in the Supporting
−
Information). The presence of BF anions was confirmed by
4
1
9
F NMR spectroscopy (Figures S15 and S24 in the Supporting
Information). Energy-dispersive X-ray (EDX) spectroscopy was
also used to characterize these complexes, which allows
elemental analyses of materials with two or more transition
15,16
metals and/or halides and determination of their ratios.
Indeed, the EDX analysis of [NiAuCl] showed a chemical
composition of Ni/Au/Cl in a ca. 1/1/1 ratio, in accordance
with the proposed structure. Conversely, a chemical composi-
tion of Ni/Au/Cl in a ca. 2/1/0 ratio was observed for
[
NiAuNi]BF , confirming that one Au cation is coordinated by
4
two NHC ligands.
Although the synthesis of heteroleptic bis-carbenic Au
complexes remains relatively scarce, some examples can be
C
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Article
generated anionic NHC in situ exerts a higher trans effect able
to weaken the Au−Cl bond in the intermediate monocarbenic
complex, thus promoting the formation of the corresponding
bis-carbenic complex. In order to verify this hypothesis, the
same reaction with Ni-BF and 3.3 equiv of KOtBu as reagents
4
was performed. The Ni(II) acts as a protecting group preventing
the appearance of negative charges in the inner core of the
porphyrin. On the basis of the same procedure, the bis-carbenic
[
NiAuNi]BF and mono-carbenic [NiAuCl] complexes were
4
obtained in 19 and 44% yields, respectively (molar ratio bis/
mono ∼15/85, Scheme 3). The increase in quantity of base
improved the yield of [NiAuCl] in comparison to the
experiment with 1.1 equiv of KOtBu (Scheme 1, procedure
B, yield of 34%). However, the high-yield formation of the bis-
carbenic [NiAuNi]BF complex did not occur.
4
Electronic and Photophysical Properties. The elec-
tronic interactions between the porphyrin moieties may be
estimated from their electronic spectra and their electro-
chemical properties. The UV−visible spectra of the
homoleptic complexes correspond to the superimposition of
the spectra of the two corresponding monomers (Figure 2 and
Figure 3. Cyclic voltammograms of [NiAuCl] (top) and [NiAuNi]-
−4
BF (bottom) in CH Cl 0.1 M TBAPF (C = 5 × 10 M, v = 0.1 V
4 2 2 6
s , working electrode glassy carbon, i.d. 3 mm).
2
5
−1
reductions at E = −1.180 and −1.410 V, leading to the anion
1
/2
•
−
2−
radical (H P ) and dianion (H P ), respectively, as expected
2
2
26
for free base porphyrins. Thus, the carbene−Au−Cl moiety is
not electroactive in the −2.0 to +2.2 V potential range. A
similar behavior is observed for [NiAuCl], with both oxidation
•+
2+
processes (Ni(II)P → Ni(II)P → Ni(II)P ) occurring at E
1
/2
=
1.015 and 1.215 V and both reductions (Ni(II)P →
•−
2−
Ni(II)P → Ni(II)P ) noted at E = −1.230 and −1.660 V.
However, for this Ni(II) complex, a third pseudoreversible
1/2
oxidation is observed at E1/2 = 1.875 V (peak O3, top of Figure
3
). This latter wave has previously been assigned to the Ni(II)/
27
Ni(III) redox couple. This peak also reveals a shoulder at
1.84 V. This unexpected additional redox system is absent
∼
from the CV of [NiAuNi]BF . This redox system likely arises
4
from an unknown product which is generated by a chemical
reaction subsequent to the electron transfer. The CVs of the
homoleptic complexes [NiAuNi]BF and [FbAuFb]BF are
4
4
practically identical with those of their respective monomers, as
exemplified in Figure 3 for [NiAuCl] and [NiAuNi]BF . The
4
maximum difference is only ±30 mV in comparison to their
redox potentials (Table 1). This similarity supports that each
porphyrin unit in the dimer does not interact, or only very
weakly, with the other porphyrin through the carbene−Au−
carbene fragment.
Figure 2. UV−visible spectra of [NiAuCl] (solid line) and
[
NiAuNi]BF (dashed line) in CH Cl at 298 K.
4 2 2
Figures S36−S38 in the Supporting Information). This fact and
the finding that there is also no substantial shifting or splitting
of the absorption bands on going from the monomeric
This feature is also observed in the CV of the heteroleptic
dimer [NiAuFb]BF , since it exactly corresponds to the
4
[
MAuCl] to the dimeric species [MAuM]BF (M = Ni, Fb)
superimposition of the CVs of complexes [NiAuCl] and
[FbAuCl] (Figure S43 in the Supporting Information). Thus,
five oxidations are observed though the first four oxidations and
appear as two merged systems and consequently only two
oxidation peaks are reliably addressable. According to the
potential values of the monomers and the expected lack of
electronic communication for this heteroleptic dimer, these five
oxidations appear to successively correspond to (i) one-
4
show that the electronic communication between the two
chromophores within dimeric species is minimal or non-
existent.
This absence of electronic communication is also confirmed
by electrochemical analyses. The cyclic voltammograms (CVs)
measured in CH Cl /0.1 M TBAPF for all species are
presented in Figure S43 in the Supporting Information (all
potential values given in the text or in the Supporting
Information are referenced vs the saturated KCl calomel
2
2
6
electron oxidation of the free base porphyrin moiety (H P →
2
•+
H P ), (ii) one-electron oxidation of the nickel(II) porphyrin
moiety (Ni(II)P → Ni(II)P ), (iii) one-electron oxidation of
the free base porphyrin (H2P → H P ), (iv) one-electron
oxidation of the nickel(II) porphyrin (Ni(II)P → Ni(II)P ),
and (v) one-electron oxidation of the nickel(II) metal into
Ni(III). In the negative potential region, four reductions can be
identified, though the first two reductions are merged.
Expectedly, these reductions appear in the following order:
2
•+
electrode, SCE). CVs of [NiAuCl] and [NiAuNi]BF are
represented in Figure 3. Table 1 gathers the redox potentials
extracted from the CVs. The cyclic voltammogram of
4
•
+
2+
2
•
+
2+
[
FbAuCl] exhibits two reversible monoelectronic porphyrin
ring centered oxidations at E = 0.925 and 1.130 V, leading to
1
/2
•+
2+
the cation radical (H P ) and dication (H P ), respectively,
and two reversible monoelectronic porphyrin ring centered
2
2
D
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Article
a
Table 1. Redox Potentials of [FbAuCl], [NiAuCl], [FbAuFb]BF , [NiAuNi]BF , and [NiAuFb]BF
4
4
4
E1/2 (ΔEp)
b
compound
1st oxidn
2nd oxidn
3rd oxidn
1st redn
2nd redn
3rd redn
HOMO−LUMO gap
[
[
[
[
[
FbAuCl]
0.925 (80)
1.015 (80)
0.945 (80)
1.025 (90)
1.06/0.915
1.13 (70)
1.215 (90)
1.14 (90)
1.21 (110)
−1.18 (80)
−1.23 (80)
−1.15 (105)
−1.21 (105)
−1.11/−1.255
−1.410 (70)
−1.660 (85)
−1.395 (80)
−1.665 (100)
−1.400 (80)
2.105
2.240
2.094
2.234
∼2.11
c
NiAuCl]
1.94/1.81
FbAuFb]BF4
NiAuNi]BF4
NiAuFb]BF4
1.855 (125)
1.855 (110)
c
c
c
1.26/1.11
−1.660 (135)
a
Abbreviations: oxidn, oxidation; redn, reduction. Unless otherwise noted, redox potentials correspond to E1/2 = (Epa + E )/2 and are given in V vs
pc
b
SCE. Values in parentheses correspond to ΔE = |E − E | and are given in mV. Experimental HOMO−LUMO gap = E1/2(1st oxidn) − E1/2(1st
redn). E /E values are given since these redox systems corresponds to the superimposition of two merging systems.
p
pa
pc
c
pa pc
(
i) first reduction corresponding to the one-electron reduction
emitting state is again the typical π-excited state. Again, the
fluorescence peaks are essentially the same between the two
species, thus corroborating the absence of electronic
communication in the excited state as well.
•−
of the free base porphyrin moiety (H P → H P ), (ii) first
one-electron reduction of the nickel(II)porphyrin (NiP →
NiP ), (iii) second one-electron reduction of free base
porphyrin (H2P → H P ), and (iv) second one-electron
reduction of the nickel(II) porphyrin (NiP → NiP ). In
conclusion, the level of electronic communication in the
homoleptic and heteroleptic dimers is essentially nonexistent.
To explain these electronic properties, computational studies
were performed. The geometries of [FbAuCl] and [FbAuFb]+
were first optimized by DFT (B3LYP; Figure 4). As expected,
2
2
•
−
•−
2−
2
Au(I) complexes with NHC ligands are considered as
•
−
2−
2,3
promising new metal-based anticancer drugs. Porphyrins are
also efficient photosensitizers (PS) for photodynamic therapy
28
(
PDT). Indeed, such porphyrin−NHC−Au(I) conjugates
may be interesting for dual therapy by combining the cytotoxic
effect of Au(I) in the dark with an additional photodynamic
effect of the porphyrin upon irradiation. To study the influence
of the peripheral Au(I) complex on the ability of the porphyrin
1
core to generate singlet oxygen ( O ) under illumination, the
2
photo-oxidation of a biological molecule such as cholesterol,
1
which can be easily monitored by H NMR spectroscopy, was
performed (Figure 5 and Figure S44 in the Supporting
29
Information). The free base 5,10,15,20-meso-tetrakis(4-tert-
butylphenyl)porphyrin (i.e., the porphyrin core of Fb-BF4
without the peripheral imidazolium ring), labeled H TPP-
2
(
tBu)4 in Figure 5, was also tested for comparison.
Interestingly, both the imidazolium salt Fb-BF and the gold
4
Figure 4. Representation of the frontier molecular orbitals and
corresponding energies for gold complexes: (a) [FbAuCl] and (b)
+
[
FbAuFb] .
the HOMO and LUMO exhibit the π-systems of the porphyrin.
Clearly, no atomic contribution of the carbene and gold units
has been computed for both complexes. This lack of
contribution unambiguously explains the absence of electronic
communication across the bridge in the dimer, as concluded by
17b,25
UV−visible spectroscopy and the CVs.
Consequently,
there is no frontier MO coupling between the two porphyrins,
thus corroborating the fact that the two porphyrins behave as
two disconnected chromophores within the dimeric species. The
fluorescence bands for both chromophores [FbAuCl] (Figures
S39 and S40 in the Supporting Information) and [FbAuFb]BF4
Figure 5. Photochemical oxidation of cholesterol. Experimental
conditions: in C D (500 μL) with cholesterol/PS = 200, cholesterol
6
6
−2
−4
(
5.2 × 10 M) and PS (2.6 × 10 M), 2h 30 min of irradiation (500
W halogen lamp, with filter λ >510 nm). Irradiation experiments were
reproduced three times. TON = turnover number, i.e. moles of
(Figures S41 and S42 in the Supporting Information) exhibit
1
oxidized cholesterol/mol of PS after 2h 30 min, estimated by H NMR
two peaks, the 0−0 component of which overlaps strongly with
that of the absorption. The excitation spectra superimpose well
with the absorption bands, indicating that the species which
emits is the same as that which absorbs. Thus, the nature of the
spectroscopy (see Figure S44 in the Supporting Information). The
asterisk (*) indicates that this PS was only partially soluble in C D : its
6
6
effective concentration in the course of the experiment was lower,
explaining the lower TON.
E
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Article
1
3
1
complex [FbAuCl] are able to photo-oxidize cholesterol. The
complex [FbAuCl] is a better PS in comparison to the
nonfunctionalized porphyrin H TPP(tBu) . (average TON
C{ H} NMR spectra were calibrated to TMS on the basis of the
1
9
relative chemical shift of the solvent as an internal standard. F NMR
spectra were calibrated to CFCl on the basis of this external reference
standard. Abbreviations used for H NMR spectra are as follows: s,
singlet; d, doublet. UV/vis absorption spectra were recorded in
3
2
4
1
1
6.3 vs 10.7). This additional phototodynamic effect may be
attributed to the “heavy atom” effect of Au(I) at the periphery
of the porphyrin, promoting the intercrossing system S → T
and causing the subsequent formation of O to occur. This is
CH Cl with a JASCO V-760 UV−visible−NIR spectrophotometer in
2
2
1
1
1
0 mm quartz cells (Hellma). High-resolution mass spectra (HRMS)
1
30
2
were recorded on ESI-TOF Q instruments in positive mode or on a
MALDI-TOF spectrometer in positive mode using dithranol as a
matrix and PEG as the internal reference. Elemental analyses were
performed using an Elementar Vario Micro Cube instrument.
Synthesis of [NiAuCl]. Procedure A. A solution of the porphyrin
consistent with the decrease in fluorescence quantum yields
(
Φ = 0.22 and 0.038) and lifetimes (τ (298 K) = 5.85 ± 0.1 ns
F
F
(λ
672 nm) and 4.08 ± 0.1 ns (λ 679 nm)) when going
em
em
1
7b
from Fb-I
to [FbAuCl] (Table S1 in the Supporting
−5
Ni-I (100 mg, 9.2 × 10 mol) was prepared in CH Cl (10 mL).
Then, Ag O (21 mg, 9.2 × 10 mol, 1 equiv) was added and the
reaction mixture was vigorously stirred at room temperature, under an
argon atmosphere protected from light. After 6 h, [AuCl(THT)] (30
mg, 9.2 × 10 mol, 1 equiv) was added and the mixture was stirred
for an additional 12 h under the same conditions. The reaction was
monitored by TLC analysis. When the reaction was complete, the
solvent was evaporated and the title compound was purified by
column chromatography (SiO ; eluent CH Cl /n-hexane 7/3).
Information). The homoleptic complex [FbAuFb]BF gen-
2
2
4
−5
1
erates O as well, but this cationic species is poorly soluble in
2
2
C D , explaining its lower activity. As expected, the Ni(II)
6
6
complexes are photochemically inert. All compounds appeared
stable under irradiation because their UV−visible spectra
remained similar during irradiation, indicating that no
decomposition of the porphyrin core occurred.
−5
2
2
2
CONCLUSION
2 2
■
Porphyrins fused to imidazolium salts were successfully used as
NHC precursors to synthesize mono- and bis-carbenic Au(I)
complexes following different synthetic procedures. The
synthesis of bis-carbenic complexes is readily straightforward
by using monocarbenic complexes as starting materials. The
[
NiAuFb]BF4 complex that now joins the family of rare
was evaporated and the title compound was purified by column
examples of heteroleptic bis-carbenic complexes was prepared.
These complexes are very stable and are easily purified by SiO2
column chromatography before recrystallization. Interestingly,
we showed for the NHC fused to the free base porphyrin that
its reactivity toward Au(I) could be modulated simply by
deprotonating the inner NH of the porphyrin with a base.
Indeed, the formation of the monocarbenic complex [FbAuCl]
was observed with the porphyrin in its free base state (i.e., with
two NH groups in the porphyrin core), whereas the bis-
chromatography (SiO ; eluent from CH Cl to CH Cl /MeOH 95/
2 2 2 2 2
5
). Crystallization from CH Cl /MeOH afforded [NiAuCl] as red
2
2
needles in 34% yield (15 mg). The starting material Ni-BF was
recovered partially after column chromatography (10 mg). H NMR
4
1
(
4
7
300 MHz, CDCl ): δ 8.71 (s, 2H, H ), 8.67 (s, 4H, Hpyrr), 8.08 (d,
3
pyrr
3
3
H, HAr ortho, J
= 8.3 Hz), 7.97 (d, 4H, H
, J
= 8.3 Hz),
= 8.3
H−H
H−H
Ar ortho
H−H
3
3
.78 (d, 4H, HAr meta, J
= 8.3 Hz), 7.72 (d, 4H, HAr meta, J
H−H
Hz), 3.15 (s, 6H, HNMe), 1.56 (s, 18H, HtBu), 1.55 (s, 18H, HtBu) ppm.
13
1
C{ H} NMR (100.6 MHz, CDCl ): δ 182.3 (Ccarbene), 152.9, 151.2,
3
144.7, 144.1, 143.6, 140.2, 137.8, 137.1, 135.3, 134.1, 132.8, 132.5,
132.4, 126.9, 125.2, 124.3, 120.8, 116.1, 37.9 (CNMe), 35.2, 35.1, 31.8
carbenic complex [FbAuFb]BF was preferentially obtained
4
when deprotonating the inner NH groups of the porphyrin
with KOtBu. For bis-carbenic complexes where the two
porphyrins are linked together by one Au(I) cation, there is
no electronic communication between the porphyrins through
the assembling metal, as demonstrated by UV−visible spec-
troscopy and electrochemical studies. According to DFT
calculations, this absence of coupling can be attributed to the
lack of atomic contribution of the carbene ligand and the Au(I)
cation in the frontier MOs. Finally, the ability of Fb-BF and
the corresponding gold complex [FbAuCl] to generate O was
demonstrated through the photo-oxidation of cholesterol. The
use of such compounds combining a metallodrug and a
photosensitizer for chemo-photodynamic dual therapy is clearly
appealing and should be developed in the future.
(CtBu), 32.7 (CtBu) ppm. UV/vis (CH
2
Cl
2
): λmax (log ε) 426 (5.41),
−1
−1
5
37 (3.76), 573 (4.26 L mol cm ) nm. HR-MS (MALDI-TOF): m/
z calcd for C H AuClN Ni [M] 1194.3900, found 1194.3892. Anal.
+
63
64
6
Calcd for C H N NiAuCl·H O [1214.37 g/mol]: C, 62.31; H, 5.48;
63
64
6
2
N, 6.92. Found: C, 62.16; H, 4.97; N, 7.02.
Synthesis of [FbAuCl]. Procedure A. This procedure was similar
to procedure A described for the synthesis of [NiAuCl]. The target
compound could not be obtained following this procedure.
Procedure B. A solution of the porphyrin Fb-BF (35 mg, 3.5 ×
4
10− mol, 1 equiv) and [AuCl(THT)] (11.2 mg, 3.5 × 10 mol, 1
5
−5
4
1
equiv) was prepared in dry THF (10 mL). Then, KOtBu (4.3 mg, 3.9
10 mol, 1.1 equiv) was added and the reaction mixture was stirred
2
−5
×
at room temperature under an argon atmosphere. After 20 h, the
solvent was evaporated and the title compound was purified by
column chromatography (SiO ; eluent from CH Cl to CH Cl /
2
2
2
2
2
MeOH 95/5). Crystallization from CH Cl /MeOH afforded
2
2
[
FbAuCl] as a purple powder in 38% yield (15 mg). The starting
EXPERIMENTAL SECTION
Materials. The syntheses of imidazolium salts Ni-I, Ni-BF , Fb-I,
■
material Fb-BF was recovered partially after column chromatography
(5 mg). H NMR (400 MHz, CD Cl ): δ 8.94 (d, 2H, H
4
1
3
JH−H =
4
2
2
pyrr,
3
and Fb-BF are described in ref 14a. Reactions were performed under
5.0 Hz), 8.86 (d, 2H, H
JH−H = 5.0 Hz), 8.80 (s, 2H, Hpyrr), 8.25
4
pyrr,
(d, 4H, HAr ortho, 3J
= 8.3 Hz), 8.00 (d, 4H, H
, J
3
= 8.3
H−H
= 8.3 Hz), 7.60 (d, 4H, HAr meta, J
argon using oven-dried glassware and Schlenk techniques. The gold
complex [AuCl(THT)] was prepared by the procedure described in
ref 31. Acetone (CHROMASOLV, for HPLC, ≥99.9%) was purchased
from Sigma-Aldrich. Dry THF and CH Cl were obtained by a
H−H
Ar ortho
3
3
Hz), 7.87 (d, 4H, HAr meta, J
= 8.3 Hz), 2.71 (s, 6H, HNMe), 1.65 (s, 18H, HtBu), 1.48 (s, 18H, HtBu),
−2.95 (broad s, 2H, HNH) ppm. C{ H} NMR (100.6 MHz,
CD Cl ,): δ 182.0 (Ccarbene), 156.2, 153.0, 151.7, 142.5, 139.5, 139.5,
139.3, 139.0, 139.0, 136.8, 135.6, 134.9, 129.0, 129.0, 125.5, 124.6,
121.8, 117.9, 37.5 (CNMe), 35.4, 35.3, 31.9 (CtBu), 31.8 (CtBu) ppm.
UV/vis (CH Cl ): λ (log ε) 429 (5.60), 527 (4.25), 566 (4.09), 599
(3.79), 661 (3.75 L mol cm ) nm. HR-MS (MALDI-TOF): m/z
calcd for C H AuClN [M + H] 1139.4781, found 1139.4768. Anal.
H−H
H−H
13
1
2
2
PureSolve MD5 solvent purification system from Innovative
Technology. Preparative purifications were performed by silica gel
flash column chromatography (Merck 40−60 μM). Solvents used as
2
2
1
19
13
1
eluents are technical grade. H, F, and C{ H} spectra were
recorded on a Bruker 300 or 400 MHz spectrometer, and all NOESY
2
2
max
−1
−1
1
+
experiments were recorded on the 400 MHz spectrometer. H and
63
67
6
F
DOI: 10.1021/acs.organomet.5b00966
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Calcd for C H N AuCl·CH Cl [1222.42 g/mol]: C, 62.77; H, 5.60;
Synthesis of [NiAuFb]BF . A solution of the porphyrin Fb-BF
6
3
66
6
2
2
4
4
−5
−5
N, 6.86. Found: C, 62.24; H, 5.28; N, 6.88.
(70 mg, 7.0 × 10 mol, 1 equiv) and [NiAuCl] (100 mg, 8.5 × 10
Synthesis of [NiAuNi]BF . From [NiAuCl] as Starting Material.
mol, 1.2 equiv) was prepared in an acetone/THF (85/15 v/v) mixture
4
−
5
−5
A solution of the porphyrin Ni-BF (100 mg, 9.5 × 10 mol, 1 equiv)
(35 mL). Then, K CO (12 mg, 8.5 × 10 mol, 1.2 equiv) was added
4
2
3
−
4
and [NiAuCl] (125 mg, 1.0 × 10 mol, 1.1 equiv) was prepared in an
and the reaction mixture was vigorously stirred at room temperature
under an argon atmosphere. After 24 h, the solvent was evaporated
and the target compound was purified by column chromatography
(SiO ; eluent from CH Cl to CH Cl /MeOH 95/5). Crystallization
acetone/THF (85/15 v/v) mixture (35 mL). Then, K CO (17 mg,
2
3
−4
1
.2 × 10 mol, 1.3 equiv) was added and the reaction mixture was
vigorously stirred at room temperature under an argon atmosphere.
After 15 h, the solvent was evaporated and the target compound was
purified by column chromatography (SiO ; eluent from CH Cl to
2
2
2
2
2
from CH Cl /n-hexane afforded [NiAuFb]BF as a purple powder in
2
2
4
1
75% yield (114 mg). H NMR (400 MHz, CD Cl ): δ 9.01 (d, 2H,
2
2
2
2
2
CH Cl /MeOH 95/5). Crystallization from CH Cl /n-pentane
Hpyrr, 3JH−H = 5.0 Hz), 8.95 (d, 2H, Hpyrr, 3JH−H = 5.0 Hz), 8.75 (s, 2H,
pyrr), 8.72 (s, 2H, Hpyrr), 8.71 (s, 4H, Hpyrr), 8.43 (d, 4H, HAr ortho,
2
2
2
2
afforded [NiAuNi]BF as red needles in 77% yield (161 mg).
H
4
3
3
From [AuCl(THT)] as Starting Material. A solution of the
JH−H = 8.2 Hz), 8.18 (d, 4H, H
, J
= 8.1 Hz), 8.12 (d, 4H,
Ar ortho
H−H
−
5
3
3
porphyrin Ni-BF4 (35 mg, 3.3 × 10
mol, 1 equiv) and
HAr ortho, J
= 8.3 Hz), 7.95 (d, 4H, H
, J
= 8.3 Hz), 7.93
H−H
H−H
Ar ortho
−5
3
3
[
AuCl(THT)] (5.3 mg, 1.7 × 10 mol, 0.5 equiv) was prepared in
(d, 4H, HAr meta, J
7.82 (d, 4H, HAr meta, J
= 8.2 Hz), 7.84 (d, 4H, HAr meta, J
= 8.1 Hz),
= 8.3
H−H
H−H
H−H
−4
3
3
dry THF (3 mL). Then, KOtBu (12.2 mg, 1.1 × 10 mol, 3.3 equiv)
was added and the reaction mixture was stirred at room temperature
under an argon atmosphere. After 1.5 h, the solvent was evaporated
and the target compound was purified by column chromatography
= 8.3 Hz), 7.75 (d, 4H, HAr meta, J
H−H
Hz), 3.19 (s, 6H, HNMe), 3.18 (s, 6H, HNMe), 1.62 (s, 18H, HtBu), 1.60
(s, 18H, HtBu), 1.56 (s, 18H, HtBu), 1.55 (s, 18H, HtBu), −2.91 (broad
s, 2H, HNH) ppm. 13C{ H} NMR (100.6 MHz, CD Cl ): δ 194.7
1
2
2
(
SiO ; eluent from CH Cl to CH Cl /MeOH 95/5). Crystallization
(Ccarbene), 194.2 (Ccarbene), 156.4, 153.3, 153.2, 151.8, 151.7, 145.1,
144.5, 143.9, 143.5, 141.1(2C), 139.8, 139.7, 139.0, 138.9, 138.4,
137.4, 137.2, 135.7, 135.5, 135.0, 134.4, 133.2, 132.8, 132.8, 129.2,
129.2, 127.2, 125.8, 125.7, 124.8, 124.6, 122.0, 121.3, 118.0, 116.5, 37.8
2
2
2
2
2
from CH Cl /n-pentane afforded [NiAuNi]BF as red needles in 48%
yield (17 mg). H NMR (400 MHz, CDCl ): δ 8.72 (s, 4H, Hpyrr),
2
2
4
1
3
3
8
8
.69 (d, 4H, Hpyrr, 3J
.11 (d, 8H, HAr ortho, J
= 5.0 Hz), 8.67 (d, 4H, Hpyrr, J
= 8.0 Hz), 7.94 (d, 8H, HAr ortho, J
= 5.0 Hz),
H−H
H−H
3
3
= 8.4
H−H
(CNMe), 37.7 (CNMe), 35.6, 35.5, 35.4, 35.3, 32.0 (CtBu), 32.0 (CtBu),
H−H
3
3
19
Hz), 7.84 (d, 8H, HAr meta, J
= 8.0 Hz), 7.72 (d, 8H, HAr meta, J
31.9 (CtBu), 31.9 (CtBu) ppm. F NMR (282 MHz, CDCl ): δ
H−H
H−H
3
10
11
=
8.4 Hz), 3.20 (s, 12H, HNMe), 1.55 (s, 36H, HtBu), 1.54 (s, 36H,
−153.52 (s, BF ), −153.58 (s, BF ). UV/vis (CH Cl ): λ (log ε)
432 (5.77), 534 (4.49), 566 (4.20), 600 (3.83), 660 (3.66 L mol
cm ) nm. HR-MS (ESI): m/z calcd for C126H130N AuNi [M −
BF4 ] 2065.9555, found 2065.9645. Anal. Calcd for
4
4
2
2
max
HtBu) ppm. 13C{ H} NMR (100.6 MHz, CDCl ): δ 193.9 (Ccarbene),
1
−1
3
−
1
1
1
53.7, 153.2, 151.4, 144.5, 143.9, 140.9, 137.7, 137.7, 136.8, 135.2,
34.0, 133.3, 133.0, 132.8, 125.7, 125.5, 124.4, 121.2, 115.9, 37.0
12
+
19
(
CNMe), 35.2, 35.0, 31.7 (C ), 31.7 (CtBu) ppm. F NMR (282.2
C126H130N AuNiBF ·3/2CH Cl [2280.35 g/mol]: C, 67.10; H,
tBu
12
4
2
2
1
0
11
MHz, CDCl ): δ −154.16 (s, BF ), −154.22 (s, BF ) ppm. UV/vis
5.87; N, 7.36. Found: C, 66.91; H, 5.71; N, 7.37.
3
4
4
−1
(
CH Cl ): λ (log ε) 429 (5.61), 538 (4.52), 571 (4.01 L mol
Electrochemical Studies. All electrochemical manipulations were
performed using Schlenk techniques under an atmosphere of dry
oxygen-free argon at room temperature (20 ± 2 °C). The supporting
2
2
max
−
1
cm ) nm. HR-MS (ESI): m/z calcd for C126H128N AuNi [M −
BF4 ] 2121.8752, found 2121.8805. Anal. Calcd for
12
2
+
−1
C126H128N AuNi BF ·CH Cl [2296.58 g/mol]: C, 66.42; H, 5.71;
electrolyte was a 0.1 mol L TBAPF6 (tetra-n-butylammonium
12
2
4
2
2
N, 7.32. Found: C, 66.35; H, 5.66; N, 7.49.
hexafluorophosphate)/CH Cl2 solution which was degassed under
2
Synthesis of [FbAuFb]BF . From [FbAuCl] as Starting Material.
vacuum before use. Voltammetric analyses were carried out in a
conventional three-electrode cell. A double-junction saturated calomel
electrode (SCE), with background electrolyte between the two frits,
was used as the reference electrode. The auxiliary electrode was a
platinum slab in an independent compartment filled with the
background electrolyte and separated from the analyzed solution by
a sintered-glass disk. For all voltammetric measurements, the working
electrode was a glassy-carbon (GC) disk electrode (i.d. 3 mm). Before
each measurement, the GC electrode was polished with a diamond
4
−
4
A solution of the porphyrin Fb-BF (100 mg, 1.0 × 10 mol, 1 equiv)
4
−
4
and [FbAuCl] (126 mg, 1.1 × 10 mol, 1.1 equiv) was prepared in an
acetone/THF (85/15 v/v) mixture (35 mL). Then, K CO (18 mg,
2
3
−4
1
.2 × 10 mol, 1.3 equiv) was added and the reaction mixture was
vigorously stirred at room temperature under an argon atmosphere.
After 15 h, the solvent was evaporated and the target compound was
purified by column chromatography (SiO ; eluent from CH Cl to
2
2
2
CH Cl /MeOH 95/5). Crystallization from CH Cl /n-hexane
2
2
2
2
+
afforded [FbAuFb]BF as a purple powder in 78% yield (163 mg).
suspension and rinsed with water. Under these conditions, the Fc /Fc
4
From [AuCl(THT)] as Starting Material. A solution of the
redox potential was found to be 0.46 V vs SCE.
DFT Calculations. All density functional theory (DFT) and time-
dependent density functional theory (TD-DFT) calculations were
−
5
porphyrin Fb-BF4 (35 mg, 3.5 × 10
mol, 1 equiv) and
−5
[
AuCl(THT)] (5.6 mg, 1.8 × 10 mol, 0.5 equiv) was prepared in
−4
32
dry THF (3 mL). Then, KOtBu (13.0 mg, 1.2 × 10 mol, 3.3 equiv)
was added and the reaction mixture was stirred at room temperature
under an argon atmosphere. After 1.5 h, the solvent was evaporated
and the target compound was purified by column chromatography
performed with Gaussian 09 at the Universite
́
de Sherbrooke with
eau Quebecois
De Calculs Hautes Performances. The DFT geometry optimizations as
the Mammouth supercomputer supported by Le Res
́
́
́
3
3
well as TD-DFT calculations were carried out using the B3LYP
method. A 6-31g* basis set was used for the central chromophores,
and a 3-21g* basis set was used for solubilizing 4-tert-butylphenyl
(
SiO ; eluent from CH Cl to CH Cl /MeOH 95/5). Crystallization
2 2 2 2 2
from CH Cl /n-hexane afforded [FbAuFb]BF as a purple powder in
4
Hpyrr, JH−H = 5.0 Hz), 8.95 (d, 4H, H
2
2
4
1
34
8% yield (17 mg). H NMR (400 MHz, CD Cl ): δ 9.02 (d, 4H,
groups. VDZ (valence double ζ) with SBKJC effective core potential
was used for Au atoms. A THF solvent field was applied to all
2
2
3
3
34
JH−H = 5.0 Hz), 8.75 (s, 4H,
= 8.0 Hz), 8.19 (d, 8H, HAr ortho,
= 8.0 Hz), 7.85 (d, 8H,
= 8.0 Hz), 3.21 (s, 12H, HNMe), 1.63 (s, 36H, HtBu),
pyrr,
3
H
pyrr), 8.45 (d, 8H, HAr ortho, J
calculations. The calculated absorption spectra were obtained from
H−H
3
3
35
JH−H = 8.0 Hz), 7.95 (d, 8H, H
, J
GaussSum 2.1.
Ar meta
H−H
3
HAr meta, J
1
(
Absorption, Emission, and Excitation Spectra. All samples
H−H
.62 (s, 36H, HtBu), −2.90 (broad s, 4H, HNH) ppm. 13C{ H} NMR
100.6 MHz, CD Cl ): δ 194.5 (Ccarbene), 156.5, 153.2, 151.8, 143.6,
1
were prepared in CH Cl or 2-MeTHF (2-methyltetrahydrofuran),
2
2
which was distilled over CaH under nitrogen. The absorption spectra
2
2
2
1
39.8, 139.7, 139.1, 138.9, 137.2 (2C), 135.5, 135.0, 129.2 (2C), 125.8,
24.6, 122.1, 118.0, 37.7 (CNMe), 35.6, 35.4, 32.0 (CtBu), 32.0 (CtBu
of the complexes were recorded at 298 K using a Varian Cary 300
spectrophotometer or a HP-8453 diode array spectrophotometer. The
steady-state emission and excitation spectra were measured at 298 K in
an airtight 1.0 cm capped quartz cell and a 5.0 mm (i.d.) NMR tube
inserted into a liquid nitrogen filled quartz EPR Dewar, respectively.
The steady state fluorescence (<820 nm) and the corresponding
excitation spectra were acquired on an Edinburgh Instruments FLS980
fluorimeter equipped with single monochromators. The fluorescence
1
)
19
10
ppm. F NMR (282.2 MHz, CDCl ): δ −153.33 (s, BF ), −153.58
3
4
11
(
s, BF ) ppm. UV/vis (CH Cl ): λ (log ε) 433 (5.86), 528 (4.53),
4 2 2 max
67 (4.39), 601 (4.24), 663 nm (4.15 L mol cm ) nm. HR-MS
−
1
−1
5
+
(
ESI): m/z calcd for C126H132N Au [M − BF ] 2010.0358, found
12
4
2
010.0419. Anal. Calcd for C126
H
132
N AuBF ·3CH Cl [2353.08 g/
12
4
2
2
mol]: C, 65.85; H, 5.91; N, 7.14. Found: C, 65.47; H, 5.74; N, 7.40.
G
DOI: 10.1021/acs.organomet.5b00966
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
lifetimes were measured on the same instrument using an LED laser
Angew. Chem., Int. Ed. 2002, 41, 1290−1309. (d) Glorius, F. Top.
Organomet. Chem. 2007, 21, 1−20. (e) Kantchev, E. A. B.; O’Brien, C.
J.; Organ, M. G. Angew. Chem., Int. Ed. 2007, 46, 2768−2813.
(f) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int. Ed. 2008, 47, 3122−
3172. (g) Alcaide, B.; Almendros, P.; Luna, A. Chem. Rev. 2009, 109,
(
excitation at 375 nm. fwhm 90 ps). The quantum yields, Φ , were
F
measured using H TPP (free base 5,10,15,20-meso-tetraphenylpor-
2
36
phyrin as the standard, Φ = 0.11).
F
X-ray Diffraction Analysis. Crystal evaluation and data collection
were performed on a Rigaku-Oxford Diffraction Gemini-S diffrac-
tometer with sealed-tube Mo Kα radiation using the CrysAlis Pro
́
3817−3858. (h) Díez-Gonzalez, S.; Marion, N.; Nolan, S. P. Chem.
Rev. 2009, 109, 3612−3676. (i) N-Heterocyclic Carbenes in Synthesis;
37
program. This program was also used for the integration of the
frames using default parameters, the correction for Lorentz and
polarization effects, and the empirical absorption correction using
spherical harmonics using symmetry-equivalent and redundant data.
The structure was solved using the ab initio iterative charge-flipping
method with parameters described elsewhere using the Superflip
program and was refined using full-matrix least-squares procedures
Nolan, S. P., Ed.; Wiley-VCH: Weinheim, Germany, 2006. (j) Droge,
̈
T.; Glorius, F. Angew. Chem., Int. Ed. 2010, 49, 6940−6952.
(
k) Fortman, G. C.; Nolan, S. P. Chem. Soc. Rev. 2011, 40, 5151−5169.
(
2) (a) Teyssot, M.-L.; Jarrousse, A.-S.; Manin, M.; Chevry, A.;
Roche, S.; Norre, F.; Beaudoin, C.; Morel, L.; Boyer, D.; Mahiou, R.;
Gautier, A. Dalton Trans. 2009, 6894−6902. (b) Oehninger, L.;
Rubbiani, R.; Ott, I. Dalton Trans. 2013, 42, 3269−3284. (c) Liu, W.;
Gust, R. Chem. Soc. Rev. 2013, 42, 755−773.
38
39
40
as implemented in CRYSTALS on all independent reflections with I
2σ(I). See page S43 in the Supporting Information to obtain more
details about the refinement procedure. Crystal data for Fb-I: formula
C H Cl IN , moiety C H N ·CH Cl I, T = 175 K, M = 1118.04,
>
(3) (a) Ray, S.; Mohan, R.; Singh, J. K.; Samantaray, M. K.; Shaikh,
M. M.; Panda, D.; Ghosh, P. J. Am. Chem. Soc. 2007, 129, 15042−
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64
67
2
6
63 65
6
2
2
r
3
crystal size 0.25 × 0.30 × 0.40 mm , triclinic, space group P1
̅
1
1
2
1
2571. (c) Weaver, J.; Gaillard, S.; Toye, C.; MacPherson, S.; Nolan, S.
3
00.574(7)°, β = 107.045(7)°, γ = 109.056(8)°, V = 2920.6(2) Å , Z =
P.; Riches, A. Chem. - Eur. J. 2011, 17, 6620−6624. (d) Rubbiani, R.;
Can, S.; Kitanovic, I.; Alborzinia, H.; Stefanopoulou, M.; Kokoschka,
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Abram, U.; Hagenbach, A.; Gust, R. J. Med. Chem. 2011, 54, 8605−
−3
−1
, ρcalcd = 1.271 g cm , μ = 0.684 mm , θ = 24.952°, experimental
max
resolution 1.05 Å, 14625 reflections measured, 7484 unique reflections,
017 reflections with I > 2σ(I), Rint = 0.065, ⟨σ(I)/I⟩ = 0.1179, 652
5
refined parameters, R1(I > 2σ(I)) = 0.1205, wR2(I > 2σ(I)) = 0.1343,
R1(all data) = 0.1577, wR2(all data) = 0.1690, GOF = 1.1220,
8
615. (f) Schuh, E.; Pfluger, C.; Citta, A.; Folda, A.; Rigobello, M. P.;
Bindoli, A.; Casini, A.; Mohr, F. J. Med. Chem. 2012, 55, 5518−5528.
g) Hackenberg, F.; Muller-Bunz, H.; Smith, R.; Streciwilk, W.; Zhu,
−3
Δρ(min/max) = −1.21/2.37 e Å .
(
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.5b00966.
■
X.; Tacke, M. Organometallics 2013, 32, 5551−5560. (h) Sivaram, H.;
Tan, J.; Huynh, H. V. Dalton Trans. 2013, 42, 12421−12428.
(i) Bertrand, B.; Stefan, L.; Pirrotta, M.; Monchaud, D.; Bodio, E.;
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Pasquali, M.; Gabbiani, C. Inorg. Chem. 2014, 53, 2396−2403.
*
S
1H and 13C{1H} NMR spectra, UV−visible and mass
spectra, and cyclic voltammograms for all compounds,
excitation and emission spectra and photophysical data
(k) Bertrand, B.; de Almeida, A.; van der Burgt, E. P. M.; Picquet, M.;
for [FbAuCl] and [FbAuFb]BF , and details of the
4
Citta, A.; Folda, A.; Rigobello, M. P.; Le Gendre, P.; Bodio, E.; Casini,
A. Eur. J. Inorg. Chem. 2014, 4532−4536. (l) Boselli, L.; Ader, I.;
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Paloque, L.; Gonzalez, G.; Benoit-Vical, F.; Valentin, A.; Hemmert, C.;
Gornitzka, H. Organometallics 2015, 34, 1046−1055.
crystallographic structure determination of Fb-I (PDF)
Crystallographic data of Fb-I (CIF)
Crystallographic data of Fb-I (CIF)
AUTHOR INFORMATION
■
(
4) (a) Mercs, L.; Albrecht, M. Chem. Soc. Rev. 2010, 39, 1903−1912.
Corresponding Author
S.R.: e-mail, sebastien.richeter@umontpellier.fr; tel, +33(0)
67-143-971.
(
b) Visbal, R.; Ospino, I.; Lopez-de-Luzuriaga, J. M.; Laguna, A.;
́
*
Gimeno, M. C. J. Am. Chem. Soc. 2013, 135, 4712−4715. (c) Li, K.;
Cheng, G.; Ma, C.; Guan, X.; Kwok, W.-M.; Chen, Y.; Lu, W.; Che, C.-
M. Chem. Sci. 2013, 4, 2630−2644. (d) Weidner, T.; Baio, J. E.;
Mundstock, A.; Grosse, C.; Karthauser, S.; Bruhn, C.; Siemeling, U.
̈
Aust. J. Chem. 2011, 64, 1177−1179. (e) Zhukhovitskiy, A. V.; Mavros,
M. G.; Van Voorhis, T.; Johnson, J. A. J. Am. Chem. Soc. 2013, 135,
4
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
The authors are grateful to the CNRS and the Agence
Nationale de la Recherche (ANR) for financial support
■
7
418−7421. (f) Crudden, C. M.; Horton, J. H.; Ebralidze, I. I.;
Zenkina, O. V.; McLean, A. B.; Drevniok, B.; She, Z.; Kraatz, H.-B.;
Mosey, N. J.; Seki, T.; Keske, E. C.; Leake, J. D.; Rousina-Webb, A.;
Wu, G. Nat. Chem. 2014, 6, 409−414.
(
research project ANR-09-JCJC-0089-01). C.H.D. acknowl-
edges the Universite de Bourgogne and the Conseil Regional de
Bourgogne for financial support. C.H.D. thanks the CNRS for
́
́
(5) (a) Hurst, E. C.; Wilson, K.; Fairlamb, I. J. S.; Chechik, V. New J.
Chem. 2009, 33, 1837−1840. (b) Vignolle, J.; Tilley, T. D. Chem.
Commun. 2009, 7230−7232. (c) Lara, P.; Rivada-Wheelaghan, O.;
Conejero, S.; Poteau, R.; Philippot, K.; Chaudret, B. Angew. Chem., Int.
Ed. 2011, 50, 12080−12084. (d) Ling, X.; Schaeffer, N.; Roland, S.;
Pileni, M.-P. Langmuir 2013, 29, 12647−12656. (e) Richter, C.;
Schaepe, K.; Glorius, F.; Ravoo, B. J. Chem. Commun. 2014, 50, 3204−
granting him the opportunity to work as a full-time researcher
for one year (“del
grateful to Dr. Fanny Picquet and Marie-Jose
analyses. P.D.H. and A.L. acknowledge the NSERC (Natural
Sciences and Engineering Research Council of Canada) for
funding and postgraduate scholarships.
́
eg
́
ation CNRS”, Sept 2015). The authors are
́
Penouilh for MS
3
̀
207. (f) Lara, P.; Suarez, A.; Colliere, V.; Philippot, K.; Chaudret, B.
ChemCatChem 2014, 6, 87−90. (g) Baquero, E. A.; Tricard, S.; Flores,
J. C.; de Jesus, E.; Chaudret, B. Angew. Chem., Int. Ed. 2014, 53,
13220−13224. (h) Crespo, J.; Guari, Y.; Ibarra, A.; Larionova, J.;
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Olmos, M. E.; Richeter, S. Dalton Trans. 2014, 43, 15713−15718.
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