Photoactivated Functionizable Tetracarbonyl(phenylpyridine)manganese(I) Complexes as CO-Releasing Molecules: A Direct Suzuki–Miyaura Cross-Coupling on a Thermally Stable CO-RM

Article abstract of DOI:10.1002/ejic.201600775

A new class of carbon monoxide-releasing molecules (CO-RMs) are reported based on a previously known tetracarbonyl phenylpyridine manganese(I) motif. A pre-functionalized CO-RM undergoes a direct Pd-catalysed Suzuki–Miyaura cross-coupling with phenylboronic acid to give a π-extended three-ring CO-RM. Cross-coupling conditions were modified to allow coupling of a morpholine-containing boronic acid on to a CO-RM, introducing drug-like functionality. An LED system was used to facilitate controlled CO-release. Irradiation using an LED (400 nm or 365 nm) gives rise to faster CO-release, with lower overall input power than traditional use of a TLC lamp (365 nm), as measured by an assay based on the conversion of deoxymyoglobin to carbonmonoxymyoglobin.

Full text of DOI:10.1002/ejic.201600775

A Journal of
Accepted Article
Title: Photoactivated functionizable tetracarbonyl phenylpyridine manganese(I) com-
plexes as CO-releasing molecules: a direct Suzuki-Miyaura cross-coupling on
a thermally-stable CO-RM
Authors: Jason Martin Lynam; Jonathan S Ward; Joshua T W Bray; Benjamin J.
Aucott; Conrad Wagner; Natalie E Pridmore; Adrian C Whitwood; James W B
Moir; Ian J S Fairlamb
This manuscript has been accepted after peer review and the authors have elected
to post their Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by using the Digital
Object Identifier (DOI) given below. The VoR will be published online in Early View as
soon as possible and may be different to this Accepted Article as a result of editing.
Readers should obtain the VoR from the journal website shown below when it is pu-
blished to ensure accuracy of information. The authors are responsible for the content
of this Accepted Article.
To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201600775
Link to VoR: http://dx.doi.org/10.1002/ejic.201600775

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
Photoactivated functionizable tetracarbonyl phenylpyridine manganese(I)
complexes as CO-releasing molecules: a direct Suzuki–Miyaura cross-
coupling on a thermally-stable CO-RM
[
a]
[a]
[a]
[a]
Jonathan S. Ward , Joshua T. W. Bray , Benjamin J. Aucott , Conrad Wagner ,
[
a]
[a]
[b]
[a]
Natalie E. Pridmore , Adrian C. Whitwood , James W. B. Moir , Jason M. Lynam*
[a]
and Ian J. S. Fairlamb*
Keywords: Carbon monoxide / CO-RM/irradiation / morpholine / Suzuki-Miyaura
A new class of carbon monoxide-releasing molecules (CO-RMs) are reported based on a previously known tetracarbonyl
phenylpyridine manganese(I) motif. A pre-functionalized CO-RM undergoes a direct Pd-catalysed Suzuki–Miyaura cross-
coupling with phenylboronic acid to give a π-extended three-ring CO-RM. Cross-coupling conditions were modified to allow
coupling of a morpholine-containing boronic acid on to a CO-RM, introducing drug-like functionality. An LED system was
used to facilitate controlled CO-release. Irradiation using an LED (400 nm or 365 nm) gives rise to faster CO-release, with
lower overall input power compared to traditional use of a TLC lamp (365 nm), as measured by an assay based on the
conversion of deoxymyoglobin to carbonmonoxymyoglobin.
Introduction
by a chemical trigger such as an enzyme. A number of enzyme-
triggered CO-RMs (ET-CORMs) have been developed in which
a ligand within the coordination sphere of a metal complex is
modified by an appropriate enzyme triggering the CO-release
Despite its deserved reputation as a highly toxic gas, carbon
monoxide has been identified as having a wide variety of
therapeutic benefits, including increased healing rates,
[
7]
process. It should also be noted that CO-RM3 has been shown
[
1],[2]
[8]
vasodilation and inhibition of bacterial growth.
A
to bind to lysozyme and that [Mn(CO)
4 2 2 2
(S CNMe{CH CO H})], a
considerable number of studies have probed the biological
effects of CO and clinical trials based on CO inhalation have
been performed to investigate the anti-inflammatory effects.
CO-RM developed by Mann and co-workers, is stable in
phosphate buffered saline for several hours however, in the
presence of myoglobin CO is rapidly released.
[
9]
[3]
An alternative method to harness the beneficial effects of CO is
to use a molecular compound which has the ability to carry and
subsequently liberate the gas. A wide range of such carbon
Photochemically stimulated liberation of CO from CO-RMs
[
10]
has received considerable recent attention.
So-called
PhotoCO-RMs do not degrade significantly over a short period
of time, either thermally or in the presence of a CO binder such
as myoglobin. The release of CO from photoCO-RMs may be
controlled by the light intensity as well as CO-RM concentration.
Although topical applications of CO-RMs (e.g. skin treatments)
would in theory allow lower wavelengths to be used (~400 nm),
for use in tissue long wavelengths are needed (> 550
nm).Indeed, the development of photoCORMS which are
[4]
monoxide-releasing molecules (CO-RMs) have been prepared
and in a pivotal series of experiments Motterlini demonstrated
that transition metal-based CO-RMs were able to mimic the
[5]
effects of CO.
CO-RMs may be thought of as a pro-drug, i.e. a means of
delivering the CO to a biological target. Therefore for a CO-RM
to be effective, liberation of CO is required which may be
[
10l, 11]
promoted through
a
number of different stimuli. Thermal
activated by low-energy light is an area of focus.
stimulus of a molecule that liberates CO when in solution is
perhaps the most direct method to initiate release. It may be
envisaged that with appropriate design, optimal CO release
rates and could be obtained. It should however, be noted that
the mechanistic processes which underpin such pathways may
PhotoCO-RMs have also found applications as potential
antibiotics. We have recently described a tryptophan-substituted
manganese complex (TryptoCORM) which undergoes CO-
dissociation when exposed to light with a wavelength of 400
[
12]
nm. Under these conditions TryptoCORM is highly effective at
inhibiting the growth of Escherichia coli, whilst being non-toxic to
mammalian cells. Poole and Schatzschneider have
[
6]
be complex.
The liberation of CO from a CO-RM may also be promoted
3
+
demonstrated the antibacterial activity of [Mn(CO)
(
3
(tpa- N)]
[
13]
tpa = tris(2-pyridylmethyl)amine) when irradiated at 365 nm.
This paper reports the development of photoactivated CO-
_
___________
a] Department of Chemistry, University of York, Heslington, York, YO10
DD
[
RMs, based on a tetracarbonyl phenylpyridine manganese(I)
scaffold. Having readily accessible, functionalisable ligand
5
Fax: +44 (0) 1904 322516
E-mail: ian.fairlamb@york.ac.uk, jason.lynam@york.ac.uk
Homepage: www.york.ac.uk/chemistry
Department of Biology, University of York, YO10 5DD.
Supporting information for this article is available on the WWW under
http://www.eurjic.org/ or from the author.
scaffolds will provide a modular approach for the synthesis of a
[10b]
large range of analogues.
Importantly, the installation of
[b]
synthetic handles onto the ligand allow for late stage
functionalisation to be carried out, the thermal sensitivity of the
1

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
Scheme 2. General reaction scheme for the preparation of CO-RMs 2a-e. (R
‘
Mn(CO)
4
’ motif require very mild conditions to prevent
=
H, F, Cl, Br, Ph).
degradation.
The parent non-functionalised compound prepared by Bruce and
co-workers has been expanded here to include a series of
Table 2. Yields obtained for complexes 2a-e.
[
14]
substituents.
These were prepared to assess how ligand
Entry
R
% Yield
4
structural changes affect the ability of the ‘Mn(CO) ’ motif to
release CO.
2a
2b
2c
2d
2e
H
88
43
83
72
72
F
Cl
Br
Ph
Results and Discussion
Initial experiments were used to establish if the tetracarbonyl
phenylpyridine manganese(I) complex would be strong
a
Crystals of 2c and 2d were obtained by layering CH
2 2
Cl
candidate for further functionalisation, by preparing a series of
complexes with varying substituents in the 4-position of the
phenyl ring. This position was chosen so that attached groups
would not sterically interfere with the manganese(I) centre, or
solutions with n-hexane. Crystals of BnMn(CO) have also been
5
obtained by sublimation. The three structures have been
confirmed by X-ray crystallography, and all details are presented
in the supplementary information. By way of an exemplar, the X-
ray structure for complex 2d is shown in Figure 1. It is interesting
to note the C(14)-Mn(1)-C(12) bond angle of 168.51(8) ° is quite
distorted from an ideal octahedron. This is due to the size of the
phenylpyridine system, which forces the system to change
geometry giving a N-Mn-C(11) bond angle of only 79.55(6) °.
This geometry could play an important role in determining the
properties of the CO-RM. The slight distortion could alter how
electron density passes from the ligand to the metal, potentially
altering the mode of CO-release.
5
give isomers when reacted with BnMn(CO) .
Scheme 1. General reaction scheme for the preparation of substituted phenyl
pyridine ligands; R =H (1a), F (1b), Cl (1c), Br (1d), Ph (1e). Compound 1a is
commercially available.
Table 1. Synthesis details for ligands 1b-e.
Entry
R
Catalyst
Base
Na
% Yield
1b
1c
1d
1e
F
AB cat (0.7 mol %)
2
CO3(aq)
79
83
59
59
Cl
Br
Ph
Pd(PPh
Pd(PPh
Pd(PPh
3
3
3
)
4
)
4
)
4
(2 mol %)
(2 mol %)
(2 mol %)
K
2
CO3(aq)
Na
2
CO3(aq)
CO3(aq)
Na
2
A series of Suzuki–Miyaura cross-couplings were used to
prepare the desired 2-aryl-pyridine ligands for use in the
cyclometallation reactions (Scheme 2), the conditions are
Figure 1. X-ray crystal structure of complex 2d. Atoms displayed
as ellipsoids at 50% probability. Hydrogen atoms have been
omitted for clarity. Crystallised from CH Cl /hexane. Selected
2 2
bond angles (°) and distances (Å): Mn(1)-C(11) = 2.0477(17) ,
Mn(1)-N(1) = 2.0638(14), Mn(1)-C(15) = 1.8007(18), Mn(1)-
C(12) = 1.8642(19), Mn(1)-C(13) = 1.8401(19), Mn(1)-C(14) =
outlined in Table 1. For compounds 1c-1e, Pd(PPh
3 4
) was used
as the catalyst. For fluorinated compound 1b an alternative di-
[15]
nuclear pyridyl-bridged palladium catalyst was used.
arylpyridines were then used in a cyclometallation reaction with
BnMn(CO) , an efficient reagent for the addition of a manganese
tetracarbonyl group to phenylpyridine.
The 2-
5
1.8544(19); C(14)-Mn(1)-C(12) = 168.51(8), C(13)-Mn(1)-C(12)
[
16]
This results in the
=
=
=
95.58(8),C(11)-Mn(1)-C(15)
96.04(7), C(15)-Mn(1)-N(1)
90.03(7) , C(12)-Mn(1)-N(1) =88.03(7), N(1)-Mn(1)-C(11) =
9.55(6).
=
=
93.25(7), C(13)-Mn(1)-N(1)
172.80(7), C(14)-Mn(1)-N(1)
formation of complexes 2a-2e; the details of preparation and
yields are shown in Scheme 3 and Table 2.
The manganese(I) complexes were isolated in moderate to
excellent yields, following a simple filtration of the reaction
solvent, followed by evaporation to give solid products. Further
purification by column chromatography on silica-gel could be
performed if required. Due to a slower rate of reaction in the
7
Myoglobin assay: determination of CO-release rates.
synthesis of 2b a further 0.2 equivalents of BnMn(CO)
needed to ensure that a pure product was obtained.
5
was
To assess how complexes 2a-e release carbon monoxide, a
myoglobin assay in phosphate buffered saline was carried out.
The assay was left in the dark for an initial period of 45 mins in
order to ascertain if the compounds are stable in the absence of
light and in the presence of sodium dithionite and myoglobin.
Figure 2 shows the CO release profiles for complex 2a-e using a
conventional UV lamp (365 nm) placed above the sample for
irradiation.
2

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
Complexes 2c and 2d were taken forward for this study. The
CO-RMs were used at concentrations of 10 and 40 µM using
either 365 nm or 400 nm narrow-band LEDs drawing a power of
2.4 W. This was attached directly to the UV-vis cuvette so that a
high percentage of light passes through the sample, unlike the
conventional method of using a TLC lamp in which the bulb is
too large to fit close to the cuvette.
Figure 3 shows a comparison of the 40µM CO-RM myoglobin
assays for complexes 2c and d when 365 nm, 400 nm LEDs
and a TLC lamp are used for irradiation.
Figure 2. CO release from 40 µM 2a and 2e (left) and 2b-d (right) using 50-60
µM myoglobin in a myoglobin assay. Irradiation with 365 nm TLC lamp. On for
2
min in a 5 min period. * indicates the start of irradiation cycles. 0-35 minutes
omitted for clarity as no change is observed throughout this period.
These CO-RMs do not release any significant quantity of CO
over a period of 45 minutes in the dark, even on the addition of
sodium dithionite. However, following the onset of irradition CO
release was observed. Complexes 2a and 2e have a similar
initial rate of CO release. With irradiation of 40 µM CO-RM, 50
µM myoglobin is saturated with CO. It is evident that the addition
of a phenyl group to the parent compound 2a does not
significantly alter the CO-releasing properties of the compound.
This is potenially a desirable feature as the structure can be
changed and the kinetics of CO release controlled by varying
light intensity.
Figure 3. CO release from 40 µM CO-RM 2c (left) and 2d (right) using 50-60
µM myoglobin. Irradiation with 365 nm TLC lamp and LEDs (400 nm, 2.4 W
and 365 nm, 2.4 W). On for 2m per 5m period. * indicates start of irradiation
cycles. 0-35 minutes omitted for clarity as no change is observed throughout
this period. Spline curves are added as a guide.
Comparing the halogen-substituted complexes 2b-d, chloro
complex 2c initially releases slower than the other two
complexes. The half life of each complex, defined as the time
taken for a 40 μM solution of CO-RM to deliver 20 μM CO to
myoglobin, has been calculated from the data in Figure 2 (Table
Irradiation from the LEDs is found to be significantly more
efficient at the same concentration compared with use of the
TLC lamp. The increased efficiency is apparent at both 365 nm
and 400 nm using the LED system indicating that this is not
simply a wavelength effect. This is especially the case for
complex 2c where the myoglobin is saturated with CO 25 mins
before the same experiment with a TLC lamp. With the use of a
3). There does not appear to be a direct relationship between
half-life and the molar absorption coefficient (Table 3) implying
that the efficiency with which the absorbed light results in CO
release is different from complex-to-complex.
½
400 nm LED, the 20 μM t value of both 2c and 2d is surpassed
after just 2 irradiation cycles. Given that the input power of the
LED is 2.4 W and that the input power of the TLC used was 6 W,
these data demonstrate the efficency of the LED system at
promoting CO-release even when irradiation is occuring away
from the absorbance maximum.
Figure 4 shows the UV-vis spectrum for complex 2d in MeCN, in
addition to the clean deoxy- to carboxy-myoglobin conversion
following irradiation by LED.
Table 3. Half-life CO-release values for complexes 2a-e, with irradiation at 365
nm using a benchtop TLC lamp. Molar absorption coefficients are also given in
acetonitrile.
Entry
R
t
½
/
 at 330 nm  at 365 nm  at 400 nm
-1 -3 -3 -3
-1
/ mol dm
-1
-1
/ mol dm
-1
mins
/ mol dm
-1
cm
cm 
cm 
2a
2b
2c
2d
2e
H
23
17
27
18
30
4054
4522
4534
4872
13166
2211
1893
2399
2683
4747
321
175
243
317
885
F
Cl
Br
Ph
Complex 2b has the fastest t
½
value of 17 mins but is
comparable with complex 2d at 18 minutes. The amount of
irradiation recieved in these experiments is 40% of the total time
(
2 mins on, 3 mins off), so theoretically the amount of irradiation
required makes these times much shorter.
The variation in these results may arise from using a TLC
lamp to irradiate the samples, leading us to exploit an LED
system for all subsequent experiments. The LED irradiation
system has been developed so that controlled light emission to
CO-RM samples over a narrow wavelength range using high
−
4
−3
Figure 4. UV spectrum in MeCN at 1.125×10 mol dm for CO-RM 2d (left)
and full spectral conversion from deoxy-Mb to carboxy-Mb (right) using 40 µM
d (spectra used to calculate the CO profile curve shown, right).
2
[
10f]
quality LEDs may be achieved.
The system can monitor the
Another myoglobin assay was also carried out with complexes
c and 2d to assess how many molecules of CO were released
current drawn from the LED so that the same light intensity can
be used in repeat experiments.
2
per molecule of CO-RM.
3

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
Figure 5 shows the 10 µM CO release profile for complexes 2c
and d and illustrates that the complexes release almost three
molecules of CO per molecule of CO-RM. This is advantageous
as a lower concentration of CO-RM is required to get the same
amount of CO released. Complex 2d releases faster than 2c
at 10 µM which tallies well with the 40 µM TLC lamp irradiation
studies.
late stage functionalisation of tetracarbonyl manganese(I)
complexes based on a 2-phenyl-pyridine ligand backbone.
[
5a]
Scheme 4. Implementing a Suzuki-Miyaura cross-coupling with catalyst 4 and
boronic acid 3 allows access to 2f at 40 °C after only 3.5 hours.
Figure 5. CO release from 10µM 2c and 2d using 50-60 µM myoglobin.
Irradiation with LED (400 nm, 2.4 W). On for 2m per 5m period. *indicates start
of irradiation cycles. 0-20 minutes omitted for clarity as no change is observed
throughout this period.
CO-RMs 2c and 2d contain an aryl halide motif, providing an
opportunity to directly functionalise these CO-RMs and alter their
5
/6
properties. Highly electrophilic η- metal (Cr/Mn/Fe) tricarbonyl
fragments have previously been used to activate aryl-halides to
the oxidative addition of Pd into C-X bonds and to facilitate
[
17]
cross-coupling. So as a proof of concept 2e was synthesised
via a Pd-catalysed Suzuki–Miyaura cross-coupling reaction of
[
18]
2d with phenylboronic acid.
The optimized conditions are
shown in
Scheme 3.
Figure 6. CO release from a 40 µM solution of CO-RM 2f using 50-60 µM
myoglobin. Irradiation with LED (400 nm, 2.4 W). On for 2 min per 5 min
period. * indicates start of irradiation cycles.
Figure 6 shows a 40 µM assay of 2f. This compound also shows
stability in the dark in the presence of sodium dithionite and then
degrades upon irradiation with the 400 nm LED, albeit at a
slightly slower rate than 2c and 2d. Whereas 2c and 2d reached
their half-lives within two irradaiton cycles, 2f required four such
cycles to surpass 20 μM Mb-CO, with a t
This is in spite of values of 6872, 2158 and 796 mol dm cm
½
value of 14 minutes.
-1
-3
-1
at 330, 365 and 400 nm respectively. This relatively slow release
may be attributed to the relatively low water solubility of this
compound, though the synthetic flexibility of this work should
allow for more water-soluble compounds to be made.
Scheme 3. Direct Suzuki–Miyaura cross-coupling on 2d to give arylated
product 2e.
The product 2e was isolated in 67
% yield following
chromatography on silica-gel. The product 2e has been Conclusions
previously prepared by cyclometallation (Scheme 1) and
1
13
comparison of H and C NMR, IR and LIFDI-MS data with the
original reported synthesis confirm the presence of cross
coupled product 1e via a different route. Crucially the conditions
employed here operate at 50 °C lower than those previously
A series of tetracarbonyl manganese(I) complexes based on a
2-phenyl-pyridine system have been prepared in two linear steps
in good yield. The manganese(I) complexes release CO
efficiently on irradiation at both 365 nm and 400 nm. They are
stable in solution until irradiation is initiated, e.g. stable to
thermal degradation / reaction with sodium dithionite. Other
reported photoCO-RMs are stable in water, although susceptible
[
18]
reported (100 °C)
considerable degradation.
as above 70 °C, 2e suffers from
Application of the previously developed conditions (Scheme 3)
to a more challenging boronic acid (3) with 2d however failed to
provide any conversion to 2f. Changing the precatalyst to the
[
20]
to deleterious interactions with sodium dithionite.
PhotoCO-
RMs 2a-f have been found to be thermally stable under the
conditions of the myoglobin assay.
Complex 2c and 2d were used at 10 µM concentrations in
myoglobin assays and release three molecules of CO per CO-
RM. The CO-RM can release the required CO at a lower
2
-aminobiphenylpalladium methanesulfonate dimer (4) in the
[
19]
presence of XPhos allowed for 2f to be isolated in 43% yield
after only 3.5 hours at 40 °C (Scheme 4). This further
exemplifies the utility of these mild reaction conditions for the
4

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
concentration compared to, for example, CO-RM-3 which only
releases one productive CO ligand.
crystalline, slightly off white solid (231 mg, 59% Yield). MP (DSC): 64 °C ;
1
H NMR (400 MHz, CDCl
3
) δ: 8.69 (dd, J = 4.8, 1.0 Hz, 1H), 7.88 (d, J =
8
1
.3 Hz, 2H), 7.76 (td, J = 8.0, 1.0 Hz, 1H), 7.70 (dd, J = 8.0 Hz, 1.0 Hz,
It has been demonstrated that complex 2d can be functionalised
by a direct Pd-catalysed cross-coupling reaction to generate
complexes 2e and 2f. Late-stage functionalisation of 2d could be
extended to improve water solubility, further conjugation to
increase the wavelength of CO release, and fluorescent tagging
for cell microscopy studies. All of these aspects are currently
being examined within our laboratories.
13
H), 7.60 (d, J = 8.3 Hz, 2H), 7.28–7.23 (m, 1H (under ref. Peak));
) δ: 156.6, 150.1, 138.5, 137.2, 132.2, 128.8,
23.8, 122.8, 120.7 ; Elemental Analysis (CHN) C : 56.15% H: 3.49% N:
.77% (Calculated : C: 56.44% H: 3.34 % N: 5.98% ); ESI-MS m/z =
33.9917 [M+H]+ (calc. for C11NH Br = 233.9913); IR (Pressed KBr
C
NMR (100 MHz, CDCl
3
1
5
2
9
disc) : 1581, 1556, 1458, 1426, 1389, 1147, 1095, 1066, 1001, 833, 772,
−
1
625, 539, 453 cm
.
[
15, 21]
2-(4-Fluoro-phenyl)pyridine (1b).
Compound 1e was synthesised
Experimental Section
using general procedure 1 using ABcat (0.007 eq., 11.6 µm, 12.2 mg), 4-
fluorobenzeneboronic acid (1.5 eq., 2.5 mmol, 502 mg). The product was
isolated as a slightly off white solid (226 mg, 79% Yield). Note: ABcat is
General experimental details. All reactions were carried out under a
nitrogen atmosphere unless otherwise stated. Chemical reagents were
purchased from Sigma Aldrich, Alfa Aesar or Frontier Scientific and used
as received. All dry solvents apart from methanol were obtained from a
Pure Solv MD-7 solvent machine and were stored in ampules under
nitrogen until required. Ether solvents used in reactions came from the
same machine but were deoxygenated by sonication with nitrogen
bubbling for 30 minutes. All TLC analysis was carried out using Merck
air stable as a solid and doesn’t need to be weighed out in a glove box.
1
3
H NMR (400MHz, CDCl ) δ: 8.67 (ddd, J = 4.8, 1.7, 1.0 Hz, 1H), 7.98
(dd, J = 9.0, 5.4 Hz 2H), 7.74 (td, J = 8.0, 1.7 Hz, 1H) , 7.67 (dt, J = 8.0,
1.0 Hz, 1H), 7.22 (ddd, J = 8.3, 4.8, 1.0 Hz, 2H), 7.15 (apr. t, J = 9.0 Hz,
13
3
1H); C NMR (100 MHz, CDCl ) δ: δ: 163.6 (d, J = 248.2 Hz), 156.7,
150.0, 137.1, 136.6 (d, J = 3.0 Hz), 128.8 (d, J = 8.5 Hz), 122.3, 121.1,
115.7 (d, J = 22.0 Hz); Elemental Analysis (CHN) C: 76.79% H: 4.71% N:
5
3
554 silica plates and spots were visualised using UV light at 254 and
65 nm. Column chromatography was carried out using silica 60 gel
7.95%(Calculated : C: 76.29% H: 4.66% N: 8.09%) ESI-MS m/z =
+
9
174.0717 [M+H] (calc. for C11NH F = 174.0713).
1
13
purchased from Sigma Aldrich. Solution H, and C NMR analysis was
carried out on Jeol ESC400, ESX400 and ECX500 spectrometers. These
were operating at 400 MHz ( H), 100 MHz ( C) frequencies for the
[
15, 21]
2-(4-Chloro-phenyl)pyridine (1c).
using general procedure 1 using 4-chlorobenzene boronic acid (1.5 eq.,
2.5 mmol, 378 mg) and 2.0 M K CO (6 ml).The product was isolated
Compound 1d was synthesised
1
13
1
appropriate experiments. H NMR spectra are reported in ppm(δ) and are
2
3(aq)
referenced to the residual NMR solvent and were processed in MNova
as a crystalline, slightly off white solid (261 mg, 83% Yield). MP(DSC):
1
v.6 software. (CHCl
3
: 7.26 ppm DMSO: 2.54 ppm). All chemical shifts in
reported C NMR spectra are reported in ppm (δ) and are referenced to
the NMR solvent. (CHCl : 77.36 ppm, DMSO: 40.45 ppm). In some
instances, the complexes did not prove to be sufficinetly stable to permit
51°C ; H NMR (400 MHz, CDCl ) δ: 8.69 (dd, J = 4.6 Hz, 0.7 Hz, 1H),
3
13
7.94 (d, J = 8.5 Hz, 2H), 7.76 (td, J = 8.0, 1.8 Hz, 1H), 7.70 (d, J = 8.0 Hz,
13
3
1H), 7.44 (d, J = 8.5 Hz, 2H), 7.27-7.22 (m, 1H (under ref. peak));
C
NMR (100 MHz, CDCl ) δ: 156.6, 150.1, 138.1, 137.2, 135.4, 129.3,
3
13
observation of the metal carbonyl resonance in the C NMR spectrum.
Mass Spectrometry was carried out using a Bruker microTOF instrument.
All data was acquired in positive ion mode using ESI or LIFDI ionisation.
High resolution spectrometry data is reported with less than 5 ppm error
unless otherwise stated. All LIFDI data reported is within 120 ppm error.
Melting points of all complexes and ligands were obtained on a Perkin
Elmer DSC 7 machine. Experiments were all ran using a ramp rate of
128.5, 122.8, 120.7; Elemental Analysis (CHN) C: 69.19% H: 4.30% N:
7.18%(Calculated : C: 69.67% H: 4.25% N: 7.39%)ESI-MS m/z =
+
190.0422 [M+H] (calc. for C NH Cl = 190.0418); IR (Pressed KBr disc):
1
1
9
1585, 1565, 1491, 1462, 1433, 1397, 1153, 1087, 1009, 985, 847, 829,
−
1
773, 734, 702, 676, 633, 613, 541, 491, 452 cm
.
[15, 21]
2-(Biphenyl)pyridine (1e).
Compound 1e was synthesised using
-
1
1
0 °C min to above the required melting temperature. The melting point
general procedure 1 (1.66 mmol of 2-bromopyridine) using biphenyl
boronic acid (1.2 eq., 1.99 mmol, 331 mg). The product was isolated as a
was taken as the onset of the observed endothermic peak. IR spectra
were taken using a Thermo-Nicolet Avatar-370 FT-IR spectrometer.
Spectra were taken in either solid state (KBr Disc or ATR), or in solution
using THF or methanol as solvents. UV-Visible spectroscopy for the
myoglobin assay and molar absorption co-efficient determination was
carried out on a JASCO V-560 spectrometer. A baseline in the required
solvent was carried out prior to starting an assay. Photo-initiated carbon
monoxide release was carried out using either a 365 nm 6W TLC lamp or
a 5W 400 nm LED directly above the solution drawing 2.4 W of power.
ABCat was prepared using a literature procedure by Fairlamb and co-
1
white solid (226 mg, 59% Yield). MP(DSC): 144 °C; H NMR (400 MHz,
CDCl
3
) δ: 8.72 (dt, J = 4.7, 1.1 Hz, 1H), 8.09 (d, J = 8.5 Hz, 2H), 7.81–
.75 (m, 2H), 7.72 (d, J = 8.5 Hz, 2H), 7.67 (d, J = 8.0 Hz, 2H), 7.47 (t, J
8.0 Hz, 2H), 7.37 (t, J = 7.3 Hz, 1H), 7.26–7.22 (m, 1H (under ref.
7
=
13
peak)); C NMR (100 MHz, CDCl
37.1 129.2, 127.9, 127.8, 127.6, 127.5, 122.5, 120.9; Elemental
Analysis (CHN): C: 87.84% H: 5.75% N: 5.92% (Calculated: C: 88.28%
3
) δ: 157.4, 150.1, 142.1, 141.0, 138.7,
1
+
H: 5.67% N: 6.06%) ESI-MS m/z = 232.1122 [M+H] (calc. for C17NH14
=
2
1
8
32.1120); IR (Pressed KBr disc): 1603, 1595, 1584, 1570, 1556, 1487,
464, 1448, 1430, 1400, 1296, 1181, 1149, 1058, 1035, 1003, 983, 906,
[
15]
workers.
Coulson
Pd(PPh
and
3 4
) was prepared using a literature procedure by
[
21]
co-workers.
2-Aminobiphenylpalladium
−1
47, 786, 752, 711, 687, 644, 625, 608, 452 cm
.
methanesulfonate dimer (4) was prepared using a literature procedure by
[
19]
Buchwald and co-workers.
I
[22]
Benzyl pentacarbonyl manganese .
To an oven-dried Schlenk tube
equipped with a magnetic stirrer under nitrogen was added mercury (3
cm ). Sodium metal (4 eq., 1.07 mmol, 246 mg) was added in small
pieces with high stirring to allow dissolution. In a separate Schlenk tube
2
under nitrogen was added Mn (CO)10 (1 eq., 2.68 mmol, 1.04 g), followed
by anhydrous, deoxygenated THF (40 ml). The THF solution was then
transferred by cannula on to the sodium amalgam and was stirred for 3
hours. In a separate Schlenk tube equipped with a magnetic stirrer under
nitrogen was added benzyl chloride (2 eq., 5.36 mmol, 617 µl / 678 mg).
The Schlenk tube containing benzyl chloride was placed in an ice bath
and put under vacuum with stirring for 60 seconds. At ambient
General procedure
1
-
synthesis of 2-(4-bromo-phenyl)pyridine
In a nitrogen atmosphere glove box, to an oven dried Schlenk
tube equipped with a magnetic stirrer was added Pd(PPh (0.02 eq.,
.033 mmol, 38.3 mg). The Schlenk tube was removed from the glove
3
[
15, 21]
(1d).
3 4
)
0
box and was attached to a Schlenk line. Under a high flow of nitrogen
was added 4-bromobenzene boronic acid (1.5 eq., 2.5 mmol, 502 mg),
followed by 2-bromopyridine (1 eq., 1.66 mmol, 158 µl/260 mg). 1.9M
Na CO (aq) (6 ml) and THF (9 ml) was then added via syringe. The
2 3
reaction was heated to 60 °C for 64 h. The reaction was allowed to cool
and deionised water (40 ml) was added. The product was extracted with
temperature, the THF solution of NaMn(CO)
into the benzyl chloride. The mixture was stirred at ambient temperature
20 °C) for 20 h. The solution was then filtered through a bed of Celite™
5
was transferred by cannula
4
dichloromethane (3 × 40 ml), dried with MgSO and filtered. The solvent
was removed under reduced pressure to yield crude product. The crude
product was purified using silica gel column chromatography using 90:10
PET ether/ethyl acetate as solvent. The solvent was removed to give a
(
and was washed with diethyl ether (5 × 20 ml). The contents were then
5

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
loaded on to silica gel and this was added on to a pad of silica (5 cm).
The pad was washed with petroleum ether (3 × 40 ml). The solvent was
removed to yield product contaminated with benzyl chloride. Benzyl
chloride was removed at 35 °C under vacuum. The product must be
broken up periodically with a spatula and put back under vacuum. A
mmol, 215 mg), 2-(4-bromo-phenyl)pyridine (1 eq., 0.75 mmol, 176 mg)
and n-hexane (12 ml) were used to prepare complex 2d. At the end of
the reaction, the Schlenk tube was stored in the freezer (−18 °C)
overnight. The product had precipitated out of solution and the hexane
solution was removed with a pipette. The yellow/brown solid product was
then dried under reduced pressure. (217 mg, 72% Yield).
slightly yellow crystalline product was obtained. (1.18 g, 76% yield). MP
1
(
2
DSC): 40 °C; H NMR (400 MHz, CDCl
3
); δ: 7.18 (m, 4H), 6.97(m, 1H),
-
1
.41 (s, 2H). IR (solution THF): 2107, 2047, 2009, 1987 cm ; ESI-MS
m/z: 286.9748 [M+H] (Calculated for MnO C H : 286.9747).
5 12 8
1
MP (DSC): 208 °C; H NMR (400 MHz, CDCl
3
) δ: 8.71 (d, J = 5.6, 1H),
+
8
.09 (d, J = 1.9 Hz, 1H), 7.88–7.78 (m, 2H), 7.61(d, J = 8.5 Hz, 1H), 7.31
13
(
dd, J = 8.5, 2.0 Hz, 1H), 7.15 (d, J = 6.7, 2.1 Hz, 1H); C NMR (126
General procedure
2
-
Synthesis of Tetracarbonyl (2-
MHz CDCl ) δ: 219.5, 214.0, 213.2, 178.6, 165.6, 154.0, 144.8, 143.3,
138.1, 127.2, 126.1, 125.1, 122.8, 119.5. Elemental Analysis (CHN) C:
3
2
8
I
[23]
phenylpyridine-κ N,C )manganese (2a).
tube equipped with a magnetic stirrer under nitrogen was added 2-
phenylpyridine (1 eq., 1 mmol, 143 µl/ 155 mg), BnMn(CO) (1 eq., 1
mmol, 286 mg) followed by dry deoxygenated n-hexane (16 ml). The
mixture was heated with stirring for 6 h. The reaction mixture was
allowed to cool to ambient temperature. The hexane solution was filtered
through a pipette packed with cotton wool and removal of solvent under
To an oven dried Schlenk
44.97% H: 1.75% N: 3.39% (Calculated: C: 45.03% H: 1.76% N: 3.50%)
+
5
ESI-MS m/z = 399.9017 [M+H] (calc. for MnC15
H
8
−
BrNO
4
= 399.9012). IR
1
(Solution: THF): 2075, 1992, 1977, 1936, 1259 cm .
2
I
Tetracarbonyl (2-(biphenyl)κ,C -pyridine-κ,N)manganese (2e). Using
the details from general procedure 2, compound 3, BnMn(CO)
5
(1 eq.,
reduced pressure yielded a pure yellow crystalline solid (284 mg, 88%
Yield). MP(DSC) : 114 °C; H NMR (400 MHz, CDCl
0.5 mmol, 143 mg), 2-(biphenyl)pyridine (1 eq., 0.5 mmol, 116 mg) and
1
3
) δ: 8.72 (d, J = 5.5
n-hexane (8 ml) were used to prepare complex 2e. At the end of the
reaction, the reaction mixture was allowed to cool to ambient temperature.
Dichloromethane (10 ml) was added to the mixture to dissolve the yellow
precipitate. The solution was filtered through cotton wool packed in a
Hz, 1H), 7.97 (d, J = 7.5 Hz, 1H), 7.87 (d, J = 8.1 Hz, 1H), 7.81–7.74 (m,
H), 7.28 (td, J = 7.5, 1.0 Hz, 1H), 7.17 (td, J = 7.5, 1.5 Hz, 1H), 7.11
2
1
3
(
1
ddd, J = 7.5, 5.5, 1.5 Hz, 1H): C NMR (100 MHz, CDCl
66.4, 153.9, 146.2, 141.7, 137.9, 130.3 124.2, 124.0, 122.4, 119.3.
Elemental Analysis (CHN): C: 56.65% H: 2.98% N: 4.06% (Calculated: C:
3
) δ: 174.9,
pipette. Removal of solvent under reduced pressure gave pure product
1
(
144 mg, 72% Yield). MP(DSC): 138 °C; H NMR (400 MHz, CDCl
3
) δ:
+
5
6.10% H: 2.51% N: 4.36% LIFDI-MS m/z = 321.0202 [M] (calc. for
NO = 320.9834). IR (Solution: THF): 2071, 1986, 1972, 1928,
600, 1576, 1477 cm
8
8
2
.74 (ddd, J = 6.0, 1.7, 1.0 Hz, 1H), 8.21 (d, J = 1.8 Hz, 1H), 7.91 (d, J =
MnC15
1
H
8
4
.0 Hz, 1H), 7.85 (d, J = 8.0 Hz, 1H), 7.83–7.77 (m, 1H), 7.77–7.70 (m,
H), 7.48 (t, J = 7.6 Hz, 2H), 7.42 (dd J = 8.0, 1.8 Hz, 1H), 7.38 (t, J = 7.5
−
1
.
13
3
Hz, 1H), 7.13 (ddd, J = 7.5, 6.0, 1.4 Hz, 1H) ; C NMR (100 MHz, CDCl )
2
I
Tetracarbonyl (2-(4-fluoro-phen)κ,C -pyridine-κ,N)Manganese (2b),
Using the details from general procedure 2, BnMn(CO) (1 eq., 0.5 mmol,
43 mg), 2-(4-fluoro-phen-4-yl)pyridine (1 eq., 0.5 mmol, 86.5 mg) and n-
hexane (8 ml) were used to prepare complex 2b. After 6 h, the reaction
mixture was allowed to cool to ambient temperature. CH Cl (10 ml) was
δ: 175.6, 166.4, 154.2, 154.6, 142.8, 141.7, 140.2, 138.2, 129.1, 127.8,
124.6, 123.6, 122.6, 119.7; Elemental Analysis (CHN) C: 63.61 % H:
5
1
3.44 % N: 3.39 % (Calculated: C: 63.49% H: 3.04% N: 3.53% ); LIFDI-
+
MS m/z = 397.0349 [M] (calc. for MnC21
H
12NO
4
= 397.0147). IR
2
2
(Solution: THF): 2073, 1989, 1974, 1932, 1602, 1582, 1562, 1477, 1475
−
1
added to dissolve the yellow precipitate. The mixture was filtered through
cotton wool and solvent was removed under reduced pressure to yield
product containing 20% starting material (1b). The impure product was
reacted with more BnMn(CO)
Addition of dichloromethane and filtration as previously mentioned
cm
.
Alternative synthesis of complex 2e via a cross-coupling reaction.
[18]
5
(0.2 eq.) at 75 °C in hexane for six hours.
This synthesis is based on
Precatalyst solution: To a dry Schlenk tube was added Pd(OAc)
a
modified literature procedure.
(1.0
2
1
yielded a pure yellow solid (74 mg , 43% Yield). MP(DSC): 163 °C;
NMR (400 MHz, CDCl ) δ: 8.69 (dt, J = 5.6, 1.2 Hz, 1H), 7.87–7.78 (m,
H), 7.75 (dd, J = 8.5, 5.1 Hz, 1H), 7.68 (dd, J = 8.5, 2.5 Hz, 1H), 7.06–
H
eq., 22 µmol, 5 mg) and XPhos (2.0 eq., 45µmol, 21.2 mg) under a high
flow of nitrogen. Dry, degassed THF (1 ml) was added to make a red
stock solution of catalyst/ligand.
3
2
7
1
1
13
3
.15(m, 1H), 6.84 (td, J = 8.5, 2.5 Hz, 1H); C NMR (100 MHz, CDCl ) δ:
79.6, 165.7, 163.6 (d, J = 256.0 Hz), 154.2, 142.4, 138.3, 127.0 (d, J =
8.0 Hz), 125.22 (d, J = 8.5 Hz), 122.5, 119.5, 111.3 (d, J = 23.0 Hz);
To a dry Schlenk tube equipped with a magnetic stirrer bar was added
complex 2d (1 eq., 0.125 mmol, 50 mg), phenyl boronic acid (1.5 eq.,
Elemental Analysis (CHN) C: 52.94% H: 2.21% N: 3.98% (Calculated: C:
0
.188 mmol, 23 mg) and K
3
PO
4
( 2.0 eq., 0.250 mmol, 34 mg). The
three times. Dry
+
5
3.12% H: 2.08% N: 4.13%) ESI-MS m/z = 339.9827 [M+H] (calc. for
FNO = 339.9812). IR (Solution: THF): 2075, 1993, 1977, 1936,
605, 1587, 1571, 1558, 1480, 1464, 1431, 1315, 1262, 1192 cm
Schlenk tube was evacuated and backfilled with N
2
MnC15
1
H
8
4
degassed toluene (1 ml) was added to the Schlenk tube and the contents
were stirred for 5 minutes at ambient temperature. Catalyst stock solution
−
1
.
(
2
60 µl) giving Pd(OAc) (1 mol%, 0.3 mg) and Xphos (2 mol%, 1.2 mg)
2
I
Tetracarbonyl (2-(4-chloro-phenyl)κ,C -pyridine-κ,N)manganese (2c).
Using the details from general procedure 2, BnMn(CO) (1 eq., 0.25
was added via syringe to the Schlenk tube. The reaction mixture was
then heated to 50 °C with vigorous stirring in the dark for 23 h. The
reaction was quenched by cooling to ambient temperature. This was then
filtered through a pipette packed with Celite™ and subsequently filtered
through a silica plug in a pipette eluting with toluene collecting small
fractions. Solvent was then removed under reduced pressure to give
crude product. The crude mixture was purified by silica gel column
5
mmol, 72 mg), 2-(4-chloro-phenyl)pyridine(1c)(1 eq., 0.25 mmol, 50 mg)
and n-hexane (4 ml) were used to prepare complex 2c. At the end of the
reaction, the reaction mixture was allowed to cool to ambient temperature.
Dichloromethane (5 ml) was added to the mixture to dissolve the yellow
precipitate. The solution was filtered through cotton wool packed in a
pipette. Removal of solvent under reduced pressure gave pure product
2 2
chromatography. It was loaded on to silica using CH Cl , and then was
1
(82 mg, 83% Yield). MP (DSC): 161 °C; H NMR (400 MHz, CDCl
3
) δ:
charged on to a column packed with 5% EtOAc: pet ether. The product
was eluted by switching to 10% and finally 15% EtOAc:Pet ether.
Removal of column solvent under reduced pressure gave product 2e as
an off white solid (32 mg, 67% yield).
8
.71 (d, J = 4.3 Hz, 1H), 7.93 (s, 1H), 7.85–7.78 (m, 2H), 7.68 (d, J = 8.0
13
Hz, 1H), 7.15(d, J = 6.5 Hz, 2H); C NMR (100 MHz, CDCl
65.7, 154.2, 144.7, 140.7, 138.4, 136.8, 125.1, 124.6, 122.9, 119.7.
Elemental Analysis (CHN) C: 50.53% H: 2.11% N: 3.72% (Calculated: C:
3
) δ: 178.2,
1
+
5
0.66% H: 1.98% N: 3.94%) LIFDI-MS m/z = 354.9831 [M] (calc. for
ClNO = 354.9444). IR (Solution: THF): 2077, 1993, 1978, 1936,
605, 1567, 1543, 1478, 1424 cm
2
Tetracarbonyl (2-(4-morpholinocarbonyl) biphenyl)κ,C -pyridine-
MnC15
1
H
7
4
I
κ,N)manganese (2f). This synthesis is based on a modified literature
−
1
.
[24]
procedure. Precatalyst solution: A dried schlenk tube equipped with
a magnetic stirrer bar was charged with 2-Aminobiphenylpalladium
methanesulfonate dimer (4) (1.0 eq., 0.01 mmol, 7.4 mg) and ligand (2.0
2
I
Tetracarbonyl
(
(2-(4-bromo-phenyl)κ,C -pyridine-κ,N)manganese
(1 eq., 0.75
2d). Using the details from general procedure 2, BnMn(CO)
5
eq., 0.02 mmol, 9.5 mg). This tube was evacuated and refilled with N
2
6

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
[
6]
(a) A. J. Atkin, S. Williams, P. Sawle, R. Motterlini, J. M. Lynam, I. J. S.
Fairlamb, A. J. Atkin, S. Williams, P. Sawle, R. Motterlini, J. M. Lynam,
I. J. S. Fairlamb, Dalton Trans. 2009, 38, 3653-3656; (b) W.-Q. Zhang, A.
J. Atkin, R. J. Thatcher, A. C. Whitwood, I. J. S. Fairlamb, J. M. Lynam,
W.-Q. Zhang, A. J. Atkin, R. J. Thatcher, A. C. Whitwood, I. J. S.
Fairlamb, J. M. Lynam, revealing the essential trends 2009, 38, 4351-
.
three times THF (1 ml) was then added and the colourless solution was
allowed to age for thirty minutes with stirring at room temperature before
use in the coupling reaction. No colour change was observed.
2
Suzuki-Miyaura Coupling of Tetracarbonyl (2-(4-bromo-phenyl)κ,C -
4
358; (c) W.-Q. Zhang, A. C. Whitwood, I. J. S. Fairlamb, J. M. Lynam,
I
pyridine-κ,N)manganese (2d) with 4-morphoninocarbonylphenyl
W.-Q. Zhang, A. C. Whitwood, I. J. S. Fairlamb, J. M. Lynam, Inorg.
Chem. 2010, 49, 8941-8952; (d) A. J. Atkin, I. J. S. Fairlamb, J. S. Ward,
J. M. Lynam, Organometallics 2012, 31, 5894-5902.
(a) S. Romanski, B. Kraus, U. Schatzschneider, J.-M. Neudörfl, S.
Amslinger, H.-G. Schmalz, Angew. Chem. Int. Ed. 2011, 50, 2392-2396;
boronic acid (3): The 0.5 M K
PO (10.6 g, 50 mmol) in deionized water (100 ml) and degassed by
performing several evacuation/N refill cycles (until bubbling stops) under
3 4
PO solution was prepared by dissolving
K
3
4
[
7]
8]
2
sonication prior to use. A dry Schlenk tube equipped with a magnetic
stirrer bar and Teflon septum was charged with 3 (1.5 eq., 0.188 mmol,
(b) S. Romanski, B. Kraus, M. Guttentag, W. Schlundt, H. Rucker, A.
Adler, J.-M. Neudorfl, R. Alberto, S. Amslinger, H.-G. Schmalz, Dalton
Trans. 2012, 41, 13862-13875; (c) S. Romanski, E. Stamellou, J. T.
Jaraba, D. Storz, B. K. Krämer, M. Hafner, S. Amslinger, H. G. Schmalz,
B. A. Yard, Free Radical Biol. Med. 2013, 65, 78-88.
G. J. L. Bernardes, T. Santos-Silva, A. Mukhopadhyay, J. D. Seixas, C. C.
Romao, M. J. Romao, J. Am. Chem. Soc. 2011, 133, 1192-1195.
4
4 mg) and 2d (1.0 eq., 0.126 mmol, 50 mg). It was then evacuated and
refilled with N three times and the aged precatalyst solution in THF (314
µl, 5 mol % Pd) and aqueous K PO (2.0 eq., 1.0 mmol, 0.5 M, 2.00 ml)
2
3
4
[
were added by syringe. The reaction was stirred at 40 °C for 3.5 hours,
after which it was opened to air and passed through a small plug of celite.
The solvent was removed under reduced pressure and the crude mixture
purified by silica gel column chromatography. It was loaded onto silica
[9]
S. H. Crook, B. E. Mann, A. J. Meijer, H. Adams, P. Sawle, D. Scapens,
R. Motterlini, Dalton Trans. 2011, 40, 4230-4235.
[10]
(a) J. Niesel, A. Pinto, H. W. Peindy N'Dongo, K. Merz, I. Ott, R. Gust, U.
Schatzschneider, Chem. Commun. 2008, 1798-1800; (b) H. Pfeiffer, A.
Rojas, J. Niesel, U. Schatzschneider, Dalton Trans. 2009, 4292-4298; (c)
W.-Q. Zhang, A. J. Atkin, I. J. S. Fairlamb, A. C. Whitwood, J. M.
Lynam, Organometallics 2011, 30, 4643-4654; (d) U. Schatzschneider,
Inorganica Chimica Acta 2011, 374, 19-23; (e) M. A. Gonzalez, N. L.
Fry, R. Burt, R. Davda, A. Hobbs, P. K. Mascharak, Inorg. Chem. 2011,
2 2
using CH Cl , and then was charged onto a column packed with 80%
EtOAc: pet ether. The product was eluted with 80% EtOAc: pet ether.
Removal of the solvent under reduced pressure provided the product as
1
a white solid (28 mg, 43% yield). MP: 146–148°C (dec); H NMR (400
2 2
MHz, CD Cl ) δ: 8.73 (d, J = 5.7 Hz, 1H), 8.18 (d, J = 1.8 Hz, 1H), 7.93 (d,
5
0, 3127-3134; (f) J. S. Ward, J. M. Lynam, J. W. B. Moir, D. E. Sanin,
A. P. Mountford, I. J. S. Fairlamb, Dalton Trans. 2012, 41, 10514-10517;
g) F. Mohr, J. Niesel, U. Schatzschneider, C. W. Lehmann, Zeitschrift
J = 8.1 Hz, 1H), 7.88 (d, J = 8.1 Hz, 1H), 7.86–7.80 (m, 1H), 7.76 (d, J =
(
7.6 Hz, 2H), 7.48 (d, J = 7.6 Hz, 2H), 7.43 (dd, J = 8.1, 1.8 Hz, 1H), 7.41
Fur Anorganische Und Allgemeine Chemie 2012, 638, 543-546; (h) M. A.
Gonzalez, M. A. Yim, S. Cheng, A. Moyes, A. J. Hobbs, P. K. Mascharak,
Inorg. Chem. 2012, 51, 601-608; (i) S. J. Carrington, I. Chakraborty, P. K.
Mascharak, Chem. Commun. 2013, 49, 11254-11256; (j) P. Govender, S.
Pai, U. Schatzschneider, G. S. Smith, Inorg. Chem. 2013, 52, 5470-5478;
–
7.33 (m, 2H), 7.15 (ddd, J = 7.2, 5.7, 1.3 Hz, 1H), 3.39-3.30 (m, 8H);
C NMR (100 MHz, CD Cl ) δ: 175.4, 165.7, 154.1, 146.1, 142.8, 141.3,
2 2
1
3
1
1
5
5
5
39.6, 138.1, 129.7, 128.5, 127.7, 127.3, 127.1, 124.3, 123.2, 122.8,
19.6, 66.9, 66.8; Elemental Analysis (CHN) C: 61.30% H: 3.70 % N:
(k) I. Chakraborty, S. J. Carrington, P. K. Mascharak, Acc. Chem. Res.
.72%
(Calculated: C: 61.19% H: 3.75% N: 5.59%); LIFDI-MS m/z =
2
4
014, 47, 2603-2611; (l) M. A. Wright, J. A. Wright, Dalton Trans. 2016,
5, 6801-6811; (m) P. C. Ford, Chem. Sci. 2016, 7, 2964-2986.
+
10.06 [M] (calc. for MnC26
H
H
19
N
2
O
6
=
510.0624); ESI-MS m/z
= 511.0696), 533.0509 [M+Na]
533.0516). IR (ATR): 2855, 2072, 1965, 1922,
629, 1603, 1580, 1561, 1474, 1456, 1427, 1277, 1257, 1114, 1010, 954,
=
+
+
11.0705 [M+H] (calc. for MnC26
20
N
2
O
6
[11]
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7

European Journal of Inorganic Chemistry
10.1002/ejic.201600775
FULL PAPER
Entry for the Table of Contents (Please choose one layout)
Layout 1:
Key Topic
Photoactivated
CO-releasing
molecules have been traditionally
irradiated using a TLC lamp. In this
paper the use of LEDs close to the
sample is reported. This gives
efficient CO release compared to a
TLC lamp. The complex shown
releases CO efficiently and can be
functionalised further with a Suzuki
reaction.
Jonathan S. Ward, Joshua T. W.
Bray, Benjamin J. Aucott, Conrad
Wagner, Natalie E. Pridmore,
Adrian C. Whitwood, James W. B.
Moir, Jason M. Lynam*, and Ian J.
S. Fairlamb*…….. Page No. – Page
No.
Photoactivated functionizable
tetracarbonyl phenylpyridine
manganese(I) complexes as CO-
releasing molecules: a direct
Suzuki–Miyaura cross-coupling on a
thermally-stable CO-RM
Keywords: Carbon monoxide/ CO-
releasing molecules/CO-RM
/
morpholine/Suzuki–Miyaura
8