Novel Ruthenium Phthalocyanine-Containing Model Complex for the Active Site of [FeFe]-Hydrogenases: Synthesis, Structural Characterization, and Catalytic H2 Evolution

Article abstract of DOI:10.1021/acs.organomet.5b01040

The first phthalocyanine (Pc) macrocycle-containing [FeFe]-hydrogenase model complex, (i-BuO)₈PcRu(CO)(-PDT)[(Ph₂P)₂NCH₂C₅H₄N]Fe₂(CO)₄ (6), has been prepared by a mult

Full text of DOI:10.1021/acs.organomet.5b01040

Article
pubs.acs.org/Organometallics
Novel Ruthenium Phthalocyanine-Containing Model Complex for the
Active Site of [FeFe]-Hydrogenases: Synthesis, Structural
Characterization, and Catalytic H2 Evolution
Li-Cheng Song,*,†,‡ Fei-Xian Luo,† Bei-Bei Liu,† Zhen-Chao Gu,† and Hao Tan†
†Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, and ‡Collaborative Innovation Center of Chemical
Science and Engineering (Tianjin), Nankai University, Tianjin 300071, China
S
* Supporting Information
ABSTRACT: The first phthalocyanine (Pc) macrocycle-
containing [FeFe]-hydrogenase model complex, (i-
BuO)8PcRu(CO)(μ-PDT)[(Ph2P)2NCH2C5H4N]Fe2(CO)4
(6), has been prepared by a multistep synthetic route. The
treatment of 4-picolylamine with Ph2PCl/Et3N in CH2Cl2 at
room temperature gave 4-picolyl-substituted azadiphosphine
(Ph2P)2NCH2C5H4N (1), whereas further treatment of 1 with
diiron complex (μ-PDT)Fe2(CO)6 in refluxing o-xylene
produced the 4-picolylazadiphosphine-chelated diiron complex
(μ-PDT)[(Ph2P)2NCH2C5H4N]Fe2(CO)4 (2). While 3,6-
dihydroxyphthalonitrile reacted with i-BuBr/K2CO3 in DMF at 80 °C to give 3,6-diisobutoxyphthalonitrile 3, further reaction
of 3 with lithium wire in refluxing i-BuOH afforded isobutoxyphthalocyanine (i-BuO)8PcH2 (4). Furthermore, 4 reacted with
Ru3(CO)12 in refluxing PhCN to give ruthenium phthalocyanine (i-BuO)8PcRu(CO)2 (5). Finally, CO substitution reaction of 5
with diiron complex 2 in the presence of Me3NO in CH2Cl2 resulted in formation of the targeted model complex 6. While all the
new compounds 1−6 were structurally characterized, complex 6 was found to be a catalyst for photoinduced H2 generation.
This is because such models might enable chemists to study the
photoinduced H2 production catalyzed by a dyad assembly that
contains a photosensitizer directly or indirectly attached to the
catalytic diiron subsite of a simple [FeFe]Hase model. To date,
although several light-driven models have been prepared, none
of them contain the well-known photosensitive phthalocyanine
(Pc) macrocycles. Phthalocyanines (Pcs) are 18 π-electron
conjugated aromatic systems formally made of four isoindole
units connected at their 1,3-positions by aza-bridges. These
two-dimensional aromatic macrocycles not only have unique
structures but also have many invaluable properties.32−34 For
example, they can present a strong absorption in the red and
near-infrared region of the solar spectrum with considerably
large extinction coefficients and high fluorescence quantum
yields. In addition, a wide range of substituents and more than
70 different metal and nonmetal atoms can be incorporated in
the Pc macrocycles by which the physicochemical and
photochemical properties of the corresponding Pc derivatives
could be modified and controlled.32−34 Therefore, to develop
the synthetic methodology of [FeFe]Hase models and to
prepare the first Pc macrocycle photosensitizer-containing
model complex, we initiated this study. Fortunately, we have
successfully synthesized such a targeted model in which the
INTRODUCTION
■
[FeFe]-hydrogenases (hereafter abbreviated as [FeFe]Hases)
are metalloenzymes that can catalyze proton reduction to
hydrogen with rapid rates in many microorganisms.1 In recent
years, [FeFe]Hases have attracted considerable attention,
largely due to their unique structure and particularly their
special catalytic function for the production of “clean” and
renewable hydrogen fuel.2 The X-ray crystallographic3−6 and
FTIR spectroscopic7−9 studies demonstrated that the active site
of [FeFe]Hases (so-called H-cluster)10 is composed of a
butterfly Fe2S2 cluster and a cubane-like Fe4S4 cluster, which are
linked together by a cysteine S atom. In addition, the two iron
atoms in the Fe2S2 cluster are coordinated by a dithiolate
cofactor and a given amount of CO and CN− diatomic ligands
(Scheme 1a). Although Szilagyi and co-workers have recently
suggested the dithiolate cofactor to be most likely an
oxadithiolate by using an X-ray crystallographic refinement to
close to atom resolution and the DFT optimizations,11 the
other groups have presented experimental evidence of 14N
HYSCORE,12a controlled metalloenzyme activation,12b and
heterolytic cleavage of H2 by an iron hydrogenase model13 to
support that the dithiolate cofactor is most likely an
azadithiolate.
Inspired by the structural information on the H-cluster
described above, synthetic chemists have designed and
prepared a variety of biomimetic models for the active site of
[FeFe]Hases.14−31 Among these prepared models, the light-
driven (or photoactive) models are of particular interest.28−31
Special Issue: Organometallics in Asia
Received: December 31, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. (a) Basic Structure of the Active Site of [FeFe]Hases (X = CH2, NH, or O); (b) Targeted Model Reported in This
Article
pyridine N atom of a simple diiron model is coordinated to the
central Ru atom of the isobutoxy-substituted phthalocyanine
macrocycle (Scheme 1b). In this article, we report the synthesis
and structural characterization of this novel model along with
its five new precursors. In addition, the photoinduced H2
production catalyzed by the targeted model is also described.
RESULTS AND DISCUSSION
■
Synthesis and Characterization of New Precursors
(Ph2P)2NCH2C5H4N (1) and (μ-PDT)[(Ph2P)2NCH2C5H4N]-
Fe2(CO)4 (2). According to our designed synthetic route to the
targeted light-driven model, the new precursors 1 and 2 should
be first prepared. As shown in Scheme 2, treatment of 4-
Scheme 2. Synthetic Route to Precursors 1 and 2
Figure 1. ORTEP view of 2 with 30% probability level ellipsoids.
Hydrogen atoms are omitted for clarity.
form two fused six-membered rings. One is the chair-shaped
Fe1S1C5C6C7S2 ring, and another is the boat-shaped
Fe2S1C5C6C7S2 ring. In addition, it also contains a 4-picolyl
picolylamine with diphenylphosphine chloride in the presence
of triethylamine in CH2Cl2 at room temperature gave the 4-
picolyl-substituted azadiphosphine 1 in 65% yield. Further CO
substitution reaction of the all-carbonyl diiron complex (μ-
PDT)Fe2(CO)6 (PDT = SCH2CH2CH2S) with azadiphos-
phine 1 in o-xylene at reflux afforded the simple 4-
picolylazadiphosphine-chelated diiron model 2 in 52% yield.
Precursors 1 and 2 are air-stable solids, which have been
characterized by elemental analysis and various spectroscopic
azadiphosphine, (Ph2P)2NCH2C5H4N, ligand, which is che-
lated between Fe1 and Fe2 atoms with a symmetrically cisoid
basal/basal coordination pattern to constitute a five-membered
Fe1P1N1P2Fe2 ferracycle. The Fe1−Fe2 bond length (2.4998
Å) of 2 is slightly shorter than that (2.5103 Å) of its parent
complex (μ-PDT)Fe2(CO)6,36 but slightly longer than those
found in other azadiphosphine-chelated diiron complexes, such
as (μ-PDT)Fe2(CO)4[(Ph2P)2N(i-Pr)] (Fe1−Fe2 = 2.4836 Å)
and (μ-PDT)Fe2(CO)4[(Ph2P)2N(n-Bu)] (Fe1−Fe2 = 2.4837
Å).35
1
techniques. For example, the H NMR spectra of 1 and 2
showed one signal at ca. 4.6 ppm for their NCH2 groups
attached to their pyridine rings, whereas the 31P{1H} NMR
spectra of 1 and 2 displayed one singlet at 62.6 and 120.2 ppm
for their two chemically equivalent P atoms. The considerably
downfield shift of the 31P{1H} NMR signal of 2 compared to
that of 1 is obviously due to the chelation of diphosphine 1
with the electron-withdrawing diiron carbonyl unit in 2. In
addition, the IR spectrum of 2 exhibited three strong
absorption bands in the range 1986−1908 cm−1 for its terminal
carbonyls, which is very close to those of the previously
reported analogues.35 The molecular structure of 2 was
unequivocally confirmed by X-ray diffraction analysis. While
Figure 1 shows its ORTEP view, Table 1 lists the selected bond
lengths and angles. As shown in Figure 1, complex 2 contains a
PDT ligand, which is bridged between Fe1 and Fe2 atoms to
Synthesis and Characterization of New Precursors
3,6-(i-BuO)2-1,2-(NC)2C6H4 (3), (i-BuO)8PcH2 (4), and (i-
BuO)8PcRu(CO)2 (5). In order to synthesize the targeted light-
driven model, the other three new precursors 3−5 should also
be prepared. Scheme 3 shows that (i) 3,6-diisobutoxyphthalo-
nitrile 3 could be prepared in 96% yield by etherification
reaction of 3,6-dihydroxyphthalonitrile with i-BuBr in the
presence of K2CO3 at 80 °C in DMF; (ii) treatment of the
isobutanol solution of 3 with lithium wire at reflux resulted in
formation of octaisobutoxyphthalocyanine 4 in 14% yield; and
(iii) the ruthenium dicarbonyl phthalocyanine 5 was prepared
in 65% yield by reaction of free phthalocyanine 4 with
Ru3(CO)12 in refluxing PhCN. It is worth noting that the
formation of 5 is unexpected since reaction of free
phthalocynine t-Bu4PcH2 with Ru3(CO)12 in refluxing PhOH
B
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 1. Selected Bond Lengths [Å] and Angles [deg] for 2
Fe(1)−C(1)
1.769(3)
P(2)−N(1)
1.723(2)
Fe(1)−P(1)
Fe(1)−S(1)
Fe(1)−Fe(2)
P(1)−Fe(1)−S(1)
P(1)−Fe(1)−S(2)
P(1)−Fe(1)−Fe(2)
N(1)−P(2)−Fe(2)
2.2043(11)
2.2510(10)
2.4998(10)
151.57(3)
87.36(3)
Fe(2)−P(2)
N(1)−C(20)
Fe(2)−S(2)
Fe(1)−S(1)−Fe(2)
P(1)−N(1)−P(2)
N(1)−P(1)−Fe(1)
P(2)−Fe(2)−Fe(1)
2.1996(11)
1.481(3)
2.2636(10)
67.29(3)
121.30(13)
112.37(8)
96.24(3)
96.87(3)
113.06(8)
Scheme 3. Synthetic Route to Precursors 3−5
gave rise to the corresponding ruthenium monocarbonyl
phthalocyanine analogue.37
the side view of Figure 3 shows that the two terminal carbonyls
C1O1 and C1AO1A are perpendicular to the metallophthalo-
cyanine macrocycle with angles of O1−C1−Ru1 (176.1°) and
C1−Ru1−C1A (180.0°). The dihedral angle between A1 and
B2 or A2 and B1(12.82°) in 5 is much smaller than that
(25.06°) of its precursor 4. To the best of our knowledge,
complex 5 is the first crystallographically characterized
metallophthalocyanine in which two terminal carbonyl ligands
are axially coordinated to the central ruthenium atom, although
some metallophthalocyanines with one axially bonded carbonyl
ligand are known and crystallographically characterized.37−39,42
Synthesis and Characterization of Model Complex (i-
BuO)8PcRu(CO)(μ-PDT)[(Ph2P)2NCH2C5H4N]Fe2(CO)4 (6).
On the basis of synthesis and structural characterization of
new precursors 1−5, we have successfully synthesized the
targeted model complex 6 via the last step in our designed
synthetic route. This step involves the CO subsitution reaction
of ruthenium dicarbonyl phthalocyanine 5 with 4-picolylazadi-
phosphine-chelated diiron complex 2 in the presence of
decarbonylating agent Me3NO·2H2O in CH2Cl2 at room
temperature to give the targeted model 6 in 61% yield
(Scheme 4).
Precursors 3−5 are also air-stable solids, which have been
characterized by elemental analysis and various spectroscopic
methods. The 1H NMR spectra of 3 and 4 displayed a doublet
at 3.80 and 4.71 ppm assigned respectively to their OCH2
groups, whereas 5 showed a multiplet in the range 4.30−4.98
ppm for its OCH2 groups. Apparently, such a considerably
1
downfield shift of the H NMR signals of 4 and 5 relative to
that of 3 is similar to their analogues due to the deshielding
effect of the phthalocyanine macrocycles.38,39 In addition, the
IR and 13C{1H} NMR spectra of 5 are also similar to its
analogues by showing one strong absorption band at 1956 cm−1
for its two terminal carbonyls and one signal at 183.6 ppm for
its two C atoms in its two terminal carbonyls.38,39 The
molecular structures of the phthalocyanine derivatives 4 and 5
were unambiguously confirmed by X-ray crystallographic study.
Their ORTEP views are presented in Figures 2 and 3, whereas
the selected bond lengths and angles are given in Tables 2 and
3, respectively. As shown in the top view of Figure 2,
compound 4 is indeed a macrocyclic molecule of
1,4,8,11,15,18,22,25-octaisobutoxyphthalocyanine. The core
skeleton of this molecule deviates remarkably from planarity
to form a saddle-shaped structure, which can be seen in the side
view of Figure 2. Similar to its analogues,40,41 the two pairs of
isoindoles A1A2 and B1B2 are turned aside in an opposite
direction. The top view of Figure 3 shows that complex 5
contains a metal atom, Ru1, that is coordinated by the four N1/
N1A/N3/N3A nitrogen atoms and the two C1O1/C1AO1A
terminal carbonyls to form an octahedral geometry. In addition,
Photoactive model 6 is an air-stable solid, and its structure
has been fully characterized by elemental analysis, spectroscopy,
and X-ray diffraction analysis. The IR spectrum of 6 showed
three strong absorption bands in the region 2000−1932 cm−1
for the terminal carbonyls attached to its iron and ruthenium
atoms.38,39,43 The 1H NMR spectrum of 6 displayed a singlet at
7.48 ppm for the eight aromatic protons attached to the four
isoindole rings in its phthalocyanine macrocycle. This 1H NMR
C
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Figure 2. (a) Top ORTEP view and (b) side ORTEP view of 4 with
30% probability level ellipsoids. Hydrogen atoms are omitted for
clarity.
Figure 3. (a) Top ORTEP view and (b) side ORTEP view of 5 with
30% and 20% probability level ellipsoids, respectively. Hydrogen
atoms are omitted for clarity.
signal is very close to that (7.47 ppm) displayed by its precursor
5. Consistent with its IR spectrum is that the 13C{1H} NMR
spectrum of 6 exhibited one signal at 180.1 ppm for the one
carbonyl attached to its ruthenium atom and two signals at
211.5 and 213.0 ppm for the four carbonyls attached to its iron
atoms. The 31P{1H} NMR spectrum of 6 showed a singlet at
119.1 ppm for its two chemically equivalent P atoms. This
31P{1H} NMR signal is very close to that (120.2 ppm) of its
precursor 2. The molecular structure of 6 was confirmed by X-
ray crystallography. The ORTEP view of 6 is depicted in Figure
4, while Table 4 lists its selected bond lengths and angles. As
shown in Figure 4, model complex 6 contains one molecule of
diiron complex 2, whose pyridine N9 atom is coordinated to
the Ru1 atom of the ruthenium monocarbonyl isobutoxyph-
thalocyanine moiety generated from ruthenium dicarbonyl
isobutoxyphthalocynine 5 by loss of one of its two terminal CO
ligands. In addition, the Ru1 atom is coordinated with the N1/
N3/N5/N7 nitrogen atoms and C95O9 terminal carbonyl
ligand. The bond length Ru1−C95 (1.849 Å) is shorter than
the corresponding Ru1−C1 bond length (1.967 Å) in its
precursor 5, and the bond length of C95O9 (1.148 Å) is
increased by 0.264 Å relative to that of C1O1 (0.884 Å) in its
precursor 5. The Fe1−Fe2 bond length (2.4733 Å) is slightly
shorter than that (2.4998 Å) of its precursor 2 due to the steric
effect between the metallophthalocyanine macrocycle and
ligand 2. It is interesting to note that complex 6 is the first
prepared and crystallographically characterized photoactive
complex with a metallophthalocyanine macrocycle that is
attached to a simple [FeFe]Hase model complex.
UV−Vis Absorption Spectra and Fluorescence Emis-
sion Spectra of Light-Driven Model 6 and Related
Compounds. To study and understand the photoinduced H2-
producing behavior catalyzed by our light-driven model 6 (see
bolow), we determined the UV−vis absorption spectra of 4−6
and fluorescence emission spectra of 5, 6, and an equimolar
mixture of 2 and 5 under the same conditions. As shown in
Figure 5, the UV−vis spectrum of free phthalocyanine 4 shows
one Soret band at 328 nm and three Q bands in the range
673−765 nm, whereas the ruthenium dicarbonyl phthalocya-
nine 5 displays one Soret band at 298 nm and two Q bands at
632 and 702 nm. It follows that the Soret and Q bands of 5 are
considerably blue-shifted respectively by a maximum of 30 or
63 nm relative to the corresponding bands of its precursor free
phthalocyanine 4 due to the ruthenium coordination effect.42,44
In addition, the UV−vis spectrum of light-driven model 6
shows one Soret band at 300 nm and two Q bands at 631 and
702 nm, which are just slightly red-shifted respectively by a
maximum of 1−2 nm relative to the corresponding bands of its
precursor 5. The fluorescence emission spectra of precursor 5,
light-driven model 6, and the equimolar mixture of simple
D
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 2. Selected Bond Lengths [Å] and Angles [deg] for 4 and 5
4
O(1)−C(9)
O(2)−C(8)
O(3)−C(21)
O(4)−C(29)
C(5)−O(1)−C(9)
C(8)−O(2)−C(13)
C(20)−N(4)−C(17)
C(3)−N(2)−C(4)
1.446(5)
1.368(5)
1.366(5)
1.436(5)
116.0(3)
115.7(3)
111.5(3)
106.5(3)
N(1)−C(4)
N(2)−C(3)
N(3)−C(3)
N(4)−C(20)
N(1)−C(4)−N(2)
N(3)−C(17)−N(4)
O(1)−C(9)−C(10)
O(2)−C(8)−C(2)
1.335(5)
1.367(5)
1.333(5)
1.367(5)
127.6(3)
127.1(4)
111.3(4)
124.3(4)
5
Ru(1)−C(1)
Ru(1)−N(3)
Ru(1)−N(1)
O(1)−C(1)
C(1)−Ru(1)−N(3)
C(1)−Ru(1)−N(1)
C(17)−N(1)−Ru(1)
C(34)−N(2)−C(17)
1.838(6)
2.005(5)
2.015(4)
1.2175(11)
91.5(3)
C(16)−N(4)
N(2)−C(17)
N(3)−C(35)
N(2)−C(34)
N(3)−Ru(1)−N(1)
C(35)−N(3)−Ru(1)
O(1)−C(1)−Ru(1)
C(35)−N(3)−C(34)
1.323(7)
1.338(7)
1.364(7)
1.388(7)
89.87(18)
124.9(4)
174.9(7)
109.6(5)
89.4(2)
125.2(4)
125.5(5)
Table 3. Selected Bond Lengths [Å] and Angles [deg] for 6
Ru(1)−C(95)
Ru(1)−N(1)
Ru(1)−N(9)
Fe(1)−Fe(2)
O(9)−C(95)−Ru(1)
C(95)−Ru(1)−N(1)
N(5)−Ru(1)−N(1)
N(1)−Ru(1)−N(3)
P(2)−Fe(2)−Fe(1)
1.849(3)
2.013(2)
2.173(2)
2.4733(7)
175.5(3)
95.44(11)
176.20(9)
89.64(9)
100.38(3)
N(1)−C(4)
P(2)−N(10)
Fe(1)−P(1)
Fe(1)−S(1)
N(1)−Ru(1)−N(9)
P(1)−Fe(1)−S(1)
S(1)−Fe(1)−S(2)
S(1)−Fe(2)−Fe(1)
C(65)−N(9)−Ru(1)
1.366(4)
1.724(2)
2.1913(9)
2.2494(9)
87.91(9)
87.65(3)
84.33(3)
56.56(2)
122.35(19)
Scheme 4. Synthetic Route to Light-Driven Model 6
model 2 and precursor 5 are recorded in Figure 6. The
fluorescence emission spectrum of 6 displays only one emission
band at 729 nm, which is slightly blue-shifted by 2 nm relative
to the corresponding band of 5 but is obviously quenched
(quenching efficiency Q = 25%) compared with that of 5. Since
the intensity of the fluorescence emission band of the
equimolar mixture of 2 and 5 is nearly the same as that of 5,
it is believed that the decreased intensity with Q = 25% of the
fluorescence emission band of 6 relative to that of 5 is most
likely due to the appropriate intramolecular electron transfer
(ET) from the photoexcited ruthenium phthalocyanine macro-
cycle to the catalytic diiron subsite of simple model 2 via the
coordinatively bonded 4-picolylazadiphosphine 1,42,44 but not
by an intermolecular collision process between molecules of
6.28a,45
Figure 4. ORTEP view of 6 with 30% probability level ellipsoids.
Hydrogen atoms are omitted for clarity.
Generally, there are two major classes of catalytic systems
used for photoinduced H2 production. The first catalytic system
consists of four separate components, namely, an electron
donor, a photosensitizer, a catalyst, and a proton source.46−52
Photoinduced H2 Production Catalyzed by Light-
Driven Model 6 with a Three-Component System.
E
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 4. Crystal Data and Structure Refinements Details for 2, 4, 5, and 6
2
4
5
6
mol formula
mol wt
cryst syst
space group
a/Å
C37H32Fe2N2O4P2S2·1.25CH2Cl2
912.56
C32H41N4O4 ·CHCl3
665.06
C66H80N8O10Ru
1246.45
C102H112Fe2N10O13P2RuS2
2024.85
triclinic
triclinic
triclinic
monoclinic
P2(1)/c
P1
P1
̅
P1
̅
̅
13.634(4)
15.907(5)
20.456(7)
74.973(9)
89.387(12)
66.619(8)
3912(2)
4
7.949(4)
14.096(7)
15.683(8)
87.595(9)
82.722(9)
77.709(8)
1703.0(15)
2
8.906(4)
12.166(5)
15.992(7)
106.291(5)
105.192(5)
97.839(4)
1563.3(12)
1
16.5432(16)
32.515(3)
20.7429(19)
90
b/Å
c/Å
α/deg
β/deg
111.0100(10)
90
γ/deg
V/Å3
10415.9(17)
4
Z
Dc/g·cm−3
abs coeff/mm−1
F(000)
index ranges
1.550
1.295
1.324
1.291
1.144
0.311
0.315
0.552
1866
700
656
4224
−17 ≤ h ≤ 17
−20 ≤ k ≤ 20
−15 ≤ l ≤ 26
33 213
−9 ≤ h ≤ 8
−15 ≤ k ≤ 16
−12 ≤ l ≤ 18
8440
−10 ≤ h ≤ 9
−14 ≤ k ≤ 14
−19 ≤ l ≤ 19
12 379
−19 ≤ h ≤ 19
−38 ≤ k ≤ 32
−20 ≤ l ≤ 24
52 145
no. of reflns
no. of indep reflns
18 459
5944
5492
18 401
2θmax/deg
55.78
50.02
50.04
50.04
R
0.0471
0.0696
0.0828
0.0435
Rw
0.1131
0.1899
0.2181
0.1135
GOF
1.048
1.015
1.140
1.075
largest diff peak, hole/e Å−3
0.928/−0.640
0.668/−0.704
2.35/−1.24
1.682/−0.536
Figure 6. Fluorescence emission spectra (λex = 630 nm) of 5, 6, and an
equimolar mixture of 2 and 5 in THF (1 × 10−5 M).
Figure 5. UV−vis spectra of 4−6 in THF (1 × 10−5 M).
The second catalytic system is composed of three separate
components, namely, an electron donor, a proton source, and a
complicated photoactive catalyst in which a photosensitizer is
attached to a simple catalyst.28−31,53−57 In order to test whether
our model 6 could be used as a photoactive catalyst to realize
expected H2 production, we carried out a study on photo-
induced H2 production using a three-component catalytic
system that contains light-driven model 6, electron donor Et3N,
and proton source H2O. It was found that H2 was indeed
generated when a THF solution of the three-component
system was irradiated by a 50 W Xe lamp with a UV cutoff filter
(λ > 400 nm). However, when the same experiment was carried
out in the absence of any one of the three components or
without light irradiation, no H2 evolution was observed. It
follows that the presence of electron donor Et3N, proton source
H2O, light-driven model 6, and light irradiation is essential for
such photoinduced H2 production. In addition, as shown in
Figure 7, the H2 production increased linearly during 140 min
irradiation and then became very slow. A total of 180 min
irradiation produced 0.13 × 10−3 mmol of H2. Such a low
catalytic efficiency is mainly due to serious decomposition of
model 6 evidenced by a color change of the dark green solution
to blue. It is interesting to note that 6 is the first
phthalocyanine-macrocycle-containing [FeFe]Hase model that
has been found to be a catalyst for photoinduced H2
production, although the catalytic efficiency is low.
To compare the photoinduced catalytic efficiency of the
light-driven model 6-containing three-component system with
the simple model 2-containing four-component system, we
further carried out a control experiment for the photoinduced
F
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
CONCLUSIONS
■
We have synthesized the first Pc-macrocycle-containing light-
driven model complex 6 via the following six separated reaction
steps: (i) amination reaction of Ph2PCl with 4-picolylamine
with the aid of Et3N to give azadiphosphine 1; (ii) CO
substitution reaction of diiron complex (μ-PDT)Fe2(CO)6 with
1 in o-xylene to produce azadiphosphine-chelated diiron
complex 2; (iii) etherification reaction of 3,6-dihydroxyph-
thalonitrile with i-BuBr/K2CO3 to afford 3,6-diisobutoxyph-
thalonitrile 3; (iv) cyclization reaction of 3 with i-BuOH/Li to
afford phthalocyanine macrocycle 4; (v) coordination reaction
of 4 with Ru3(CO)12 to yield ruthenium dicarbonyl
phthalocyanine 5; and finally (vi) CO substitution reaction of
5 with diiron complex 2 to yield the targeted model 6. The X-
ray crystallographic study on metallophthalocyanine 5 confirms
that it is a ruthenium dicarbonyl phthalocynine molecule, in
which its Ru(II) center is coordinated to four N atoms of the
Pc macrocycle and its two terminal CO ligands are
perpendicular to the Pc macrocycle plane. Interestingly, 5 is
the first crystallographically characterized metallophthalocya-
nine in which two terminal CO ligands are axially coordinated
to the central metal atom. In addition, the X-ray crystallo-
graphic study on model 6 confirms that it is indeed a dyad
assembly that contains one molecule of the 4-picolylazadiphos-
phine-chelated diiron complex 2 and the pyridine N atom of
complex 2 is coordinated to the Ru(II) center of the ruthenium
isobutoxyphthalocyanine macrocycle. Particularly worth noting
is that the three-component system consisting of model 6,
electron donor Et3N, and proton source H2O has been found
to be a catalytic system for photoinduced H2 production,
although the production efficiency is low due to the weak
intramolecular ET from the excited RuPc macrocycle to the
catalytic diiron subsite of simple model 2 as well as serious
decomposition of light-driven model 6 under such photo-
catalytic conditions.
Figure 7. Time dependence of photoinduced H2 production from a
THF (4 mL) solution of Et3N (1.44 M) and H2O (4 mL) catalyzed by
light-driven model 6 (0.10 mM).
H2 production using the four-component system consisting of
simple model 2, electron donor Et3N, photosensitizer Ru
phthalocyanine 5, and proton source H2O. The experiment was
conducted under the same conditions as those using the three-
component system involving light-driven model 5. As a result,
no H2 evolution was observed during 120 min light irradiation.
It follows that the intermolecular ET from the photoexcited
photosensitizer 5 to the catalytic diiron subsite of simple model
2 could not occur. This is consistent with the aforementioned
spectral study that the fluorescence emission spectrum of the
equimolar mixture of 2 and 5 is almost the same as that of 5.
According to the above-mentioned fluorescence spectral
study and photoinduced H2 production study as well as the
previously reported mechanisms for photoinduced H2
production catalyzed by other light-driven models (such as
the photosensitizer porphyrin or C60-containing models),58,59
we might suggest a pathway to account for the photoinduced
H2 production catalyzed by light-driven model 6. As shown in
Figure 8, when model 6 is irradiated, the electron of the Pc
EXPERIMENTAL SECTION
■
General Comments. All reactions were performed by using
standard Schlenk and vacuum-line techniques under highly prepurified
N2. Solvents were distilled under nitrogen by using standard
60
procedures. (μ-PDT)Fe2(CO)6 was prepared according to the
published method. Other chemicals such as 4-picolylamine, 3,6-
dihydroxyphthalonitrile, Ph2PCl, Me3NO·2H2O, Ru3(CO)12, and
Ru(bpy)3Cl2·6H2O were purchased from commercial suppliers and
used without further purification. Preparative TLC was carried out on
glass plates (26 × 20 × 0.25 cm) coated with silica gel H (10−40 μm).
IR spectra were recorded on a Bruker Tensor 27 infrared
spectrophotometer. 1H, 13C{1H}, and 31P{1H} NMR spectra were
taken on a Bruker Avance 400 NMR spectrometer. Elemental analyses
were performed with an Elementar Vario EL analyzer. UV−vis spectra
and fluorescence emission spectra were recorded using a Hitachi U-
3900 spectrophotometer and a Hitachi F-4600 spectrophotometer,
respectively. Melting points were determined on an X-4 microscopic
melting point apparatus and were uncorrected.
Preparation of (Ph2P)2NCH2C5H4N (1). A 100 mL three-necked
flask equipped with a dropping funnel, a mechanical agitator, and a
serum cap was charged with 4-picolylamine (0.56 g, 5.0 mmol),
triethylamine (1.02 g, 10.0 mmol), and 20 mL of CH2Cl2. After the
mixture was cooled to 0 °C, a solution of diphenylphosphine chloride
(2.21 g, 10.0 mmol) in 10 mL of CH2Cl2 was dropwise added, and
then the new mixture was stirred at room temperature for 4 h. After
removal of the volatiles at reduced pressure, the residue was washed
thoroughly with water (3 × 10 mL) and ethyl alcohol (3 × 5 mL) and
finally dried under vacuum to give 1 as a white solid (1.55 g, 65%), mp
136−138 °C. Anal. Calcd for C30H26N2P2: C, 75.62; H, 5.50; N, 5.88.
Figure 8. Suggested pathway for photoinduced H2 production
catalyzed by model 6.
moiety in 6 can be excited to give 6*. Then, the excited
electron can be transferred intramolecularly to the diiron-PDT
unit to give the charge-separated species 6 . After 6 reduces
protons to give H2, it becomes 6+ with a positive charge on the
Pc moiety of 6. Furthermore, when 6+ gets one electron from
the sacrificial electron donor D, the photocatalyst 6 is
regenerated and the catalytic cycle is completed. Finally, it
should be noted that although this suggested pathway appears
to be reasonable, some details regarding this pathway still need
to be further investigated.
G
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Found: C, 75.54; H, 5.46; N, 5.81. IR (KBr disk): νC−H 3069 (s), 3052
(s), νCN 1599 (s), νCC 1478 (s), 1433 (vs), νC−N 1265 (s), νC−P
1091 (vs), νN−P 1057 (s) cm−1. 1H NMR (400 MHz, CDCl3): 4.52 (t,
3JP−H = 10.8 Hz, 2H, NCH2), 6.64 (d, J = 5.2 Hz, 2H, m-H of NC5H4),
7.28−7.38 (m, 20H, 4C6H5), 8.26 (d, J = 5.2 Hz, 2H, o-H of NC5H4)
ppm. 13C{1H} NMR (100 MHz, CDCl3): 55.5 (NCH2), 123.4, 128.4,
129.2, 132.8, 133.1, 138.9, 149.2 (C6H5, NC5H4) ppm. 31P{1H} NMR
(162 MHz, CDCl3, 85% H3PO4): 62.6 (s) ppm.
Preparation of (μ-PDT)[(Ph2P)2NCH2C5H4N]Fe2(CO)4 (2). A
100 mL three-necked flask equipped with a reflux condenser, a
magnetic stir-bar, and a serum cap was charged with 1 (0.476 g, 1.0
mmol), (μ-PDT)Fe2(CO)6 (0.386 g, 1.0 mmol), and 50 mL of o-
xylene. After the stirred mixture was refluxed for 1 h, solvent was
removed at reduced pressure, and then the residue was subjected to
TLC separation with CH2Cl2/ethyl acetate (v/v = 30:1) as eluent.
From the major red band, 2 was obtained as a red solid (0.419 g,
52%), mp 240−241 °C. Anal. Calcd for C37H32Fe2N2O4P2S2: C, 55.11;
H, 4.00; N, 3.47. Found: C, 55.07; H, 4.06; N, 3.19. IR (KBr disk):
νCO 1986 (s), 1955 (vs), 1908 (s) cm−1. 1H NMR (400 MHz,
CDCl3): 2.10 (br s, 2H, CH2CH2CH2), 2.24, 2.48 (2br s, 4H, 2SCH2),
4.66 (br s, 2H, NCH2), 6.99−7.77 (m, 24H, 4C6H5, NC5H4) ppm.
13C{1H} NMR (100 MHz, CDCl3): 25.3 (CH2CH2CH2), 31.3
(SCH2), 52.4 (NCH2), 127.5, 128.2, 128.3, 128.4, 130.2, 131.5,
132.2, 132.8, 132.9, 135.1, 139.2 (C6H5, NC5H4), 212.6, 214.4 (C
O) ppm. 31P{1H} NMR (162 MHz, CDCl3, 85% H3PO4): 120.2 (s)
ppm.
chromatography with toluene/THF (v/v = 30:1) as eluent. From the
major dark green band, 5 was obtained as a dark green solid (0.065 g,
52%), mp 175−177 °C. Anal. Calcd for C66H80N8O10Ru: C, 63.60; H,
6.47; N, 8.99. Found: C, 63.35; H, 6.37; N, 9.01. IR (KBr disk): νC−H
2957 (s), 2927 (s), 2871 (s), νCO 1956 (vs), νCN 1595 (s), νCC
1499 (vs), 1469 (s), νC−O 1237 (s), 1209 (vs), νC−N 1058 (vs) cm−1.
1H NMR (400 MHz, d6-C6D6): 1.00−1.32 (m, 48H, 16CH3), 2.36−
2.68 (m, 8H, 8CH), 4.30−4.98 (m, 16H, 8OCH2), 7.47 (s, 8H,
4NC8H2 of Pc ring) ppm. 13C{1H} NMR (100 MHz, d6-C6D6) 19.7,
19.8 (CH3), 28.7 (CH), 79.6 (OCH2), 119.6, 130.1, 143.8, 151.3
(NC8H2 of Pc ring), 183.6 (CO) ppm. UV−vis (THF, 1 × 10−5
M): λmax (log ε) = 298 (4.82), 632 (4.61), 702 (5.24) nm.
Preparation of (i-BuO)8PcRu(CO)(μ-PDT)[(Ph2P)2NCH2C5H4N]-
Fe2(CO)4 (6). A 100 mL three-necked flask equipped with a magnetic
stir-bar and two serum caps was charged with 5 (0.062 g, 0.05 mmol),
Me3NO·2H2O (0.011 g, 0.1 mmol), and 20 mL of CH2Cl2. The
mixture was stirred at room temperature for 1 h, and then 2 (0.081 g,
0.1 mmol) was added. The resulting mixture was stirred for another 2
h at room temperature. After removal of the solvent at reduced
pressure, the residue was subjected to silica gel column chromatog-
raphy with toluene/THF (v/v = 90:1) as eluent. From the black-green
band, 6 was obtained as a black solid (0.062 g, 61%), mp 216−218 °C.
Anal. Calcd for C102H112Fe2N10O13P2RuS2: C, 60.50; H, 5.58; N, 6.92.
Found: C, 60.25; H, 5.42; N, 7.15. IR (KBr disk): νC−H 2956 (s), 2930
(m), 2871 (m), νCO 2000 (s), 1968 (vs), 1932 (s), νCN 1596 (m),
νCC 1498 (s), 1469 (m), 1434 (m), νC−O 1265 (m), 1238 (m), 1208
1
(vs), νC−N 1110 (m), 1058 (s) cm−1. H NMR (400 MHz, d6-C6D6):
Preparation of 3,6-(i-BuO)2-1,2-(NC)2C6H4 (3). A 250 mL three-
necked flask equipped as that for the preparation of 2 was charged with
3,6-dihydroxyphthalonitrile (8.0 g, 50 mmol), i-BuBr (16.3 mL, 150
mmol), K2CO3 (41.4 g, 200 mmol), and 150 mL of DMF. The
reaction mixture was stirred at 80 °C for 16 h. After the mixture was
cooled to room temperature, it was poured into 800 mL of ice water.
The resulting white solid was filtered and washed thoroughly with
water and dried in air. 3 was obtained as a white solid (13.0 g, 96%),
mp 194−196 °C. Anal. Calcd For C16H20N2O2: C, 70.56; H, 7.40; N,
10.29. Found: C, 70.41; H, 7.23; N, 10.18. IR (KBr disk): νC−H 2975
(s), 2932 (m), 2904 (m), 2874 (m), νCN 2223 (s), νC−O 1287 (vs),
1.27 (d, J = 2.8 Hz, 48H, 16CH3), 1.41 (br s, 2H, CH2CH2CH2), 1.57,
1.67 (2br s, 4H, 2SCH2), 1.94 (br s, 2H, NCH2), 2.71−2.81 (m, 8H,
8CH), 3.28, 3.29 (2s, 4H, NC5H4), 4.64−4.70, 5.02−5.07 (2m, 16H,
8OCH2), 5.78, 6.63, 6.83, 7.39 (4br s, 20H, 4C6H5), 7.48 (s, 8H,
4NC8H2 of Pc ring) ppm. 13C{1H} NMR (100 MHz, d6-C6D6): 18.5,
18.7 (CH3), 23.6 (CH2CH2CH2), 27.9 (CH), 29.9 (SCH2), 48.6
(NCH2), 79.0 (OCH2), 116.4, 118.5, 125.2, 128.4, 129.4, 129.6, 130.0,
131.4, 131.6, 131.8, 133.1, 137.6, 137.9, 138.1, 139.8, 142.1, 144.9,
151.1 (C6H5, NC5H4, NC8H2 of Pc ring), 180.1 (RuCO), 211.5,
213.0 (FeCO) ppm. 31P{1H} NMR (162 MHz, d6-C6D6, 85%
H3PO4): 119.1 (s) ppm. UV−vis (THF, 1 × 10−5 M): λmax (logε) =
300 (4.83), 631 (4.56), 702 (5.21) nm.
Photoinduced H2 Production Catalyzed by Light-Driven
Model 6. A 30 mL Schlenk flask fitted with a N2 inlet tube, a serum
cap, a magnetic stir-bar, and a water-cooling jacket was charged with
model 6 (2.03 mg, 0.001 mmol), Et3N (2 mL, 14.4 mmol), H2O (4
mL), and THF (4 mL). The resulting solution was stirred and
irradiated for 120 min at about 25 °C (controlled by the cooling
jacket) through a UV cutoff filter (λ > 400 nm) by using a 50 W Xe
lamp. During the photoinduced catalytic reaction, the evolved H2 was
withdrawn periodically using a gastight syringe and analyzed by gas
chromatography with a Shimadazu GC-2014 instrument equipped
with a thermal conductivity detector and a carbon molecular sieves
column (3 mm × 2.0 m) and with N2 as the carrier gas. The total
amount of H2 produced during 120 min of irradiation was 0.13 × 10−3
mmol.
X-ray Structure Determinations of 2, 4, 5, and 6. Single
crystals of 2 suitable for X-ray diffraction analysis were grown by slow
diffusion of hexane into its CH2Cl2 solution at about −5 °C, whereas
single crystals of 4, 5, and 6 suitable for X-ray diffraction analyses were
grown by slow diffusion of methanol into their CHCl3 solutions at
about −5 °C. A single crystal of 2 or 5 was mounted on a Rigaku MM-
007 (rotating anode) diffractometer equipped with a Saturn 724 CCD.
Data were collected at 113 K by using a confocal monochromator with
Mo Kα radiation (λ = 0.710 73 Å) in the ω−θ scanning mode. Data
collection, reduction, and absorption correction were performed with
the CRYSTALCLEAR program.61 A single crystal of 4 or 6 was
mounted on a Bruker APEX-II CCD diffractometer. Data were
collected at 173 K using a graphite monochromator with Mo K
radiation (0.710 73 Å) in the ω−θ scanning mode. Absorption
correction was performed by the SADABS program.62 All structures
were solved by direct methods using the SHELXS-97 program63 and
refined by full-matrix least-squares techniques (SHELXL-97)64 on F2.
1
1269 (s) cm−1. H NMR (400 MHz, CDCl3): 1.05 (d, J = 6.4 Hz,
12H, 4CH3), 2.09−2.20 (m, 2H, 2CH), 3.80 (d, J = 6.4 Hz, 4H,
2OCH2), 7.14 (s, 2H, C6H2) ppm. 13C{1H} NMR (100 MHz,
CDCl3): 19.1 (CH3), 28.3 (CH), 76.4 (OCH2), 105.2, 113.2, 118.7,
155.4 (CN, C6H2) ppm.
Preparation of (i-BuO)8PcH2 (4). The same equipped flask as that
for the preparation of 2 was charged with 3 (2.72 g, 10.0 mmol) and
60 mL of isobutanol. While stirring, the mixture was heated to 80 °C,
and then lithium wire (2.10 g, 300 mmol) was added in portions. The
resulting mixture was refluxed for 3 h. After the mixture was cooled to
room temperature, it was poured into 250 mL of ice water. The
mixture was extracted with CH2Cl2 (3 × 20 mL). The combined
organic phase was washed with brine and dried with anhydrous
MgSO4. After removal of the drying agent and volatiles, the residue
was subjected to neutral Al2O3 column chromatography with toluene/
THF (v/v = 60:1) as eluent. From the major green band, 4 was
obtained as a green solid (0.382 g, 14%), mp >300 °C. Anal. Calcd for
C64H82N8O8: C, 70.43; H, 7.57; N, 10.27. Found: C, 70.26; H, 7.37;
N, 10.10. IR (KBr disk): νN−H 3305 (m), νC−H 2956 (s), 2910 (m),
2871 (m), νCN 1598 (s), νCC 1499 (vs), 1468 (s), νC−O 1271 (vs),
1237 (vs), νC−N 1035 (vs) cm−1. 1H NMR (400 MHz, d6-C6D6): 1.26
(d, J = 6.8 Hz, 48H, 16 CH3), 2.64−2.74 (m, 8H, 8CH), 4.71 (d, J =
6.8 Hz, 16H, 8OCH2), 7.52 (s, 8H, 4NC8H2 of Pc ring) ppm. 13C{1H}
NMR (100 MHz, d6-C6D6): 19.6 (CH3), 28.6 (CH), 79.1 (OCH2),
119.2, 126.9, 149.1, 151.9 (NC8H2 of Pc ring) ppm. UV−vis (THF, 1
× 10−5 M): λmax (log ε) = 328 (4.79), 673 (4.56), 748 (5.09), 765
(5.13) nm.
Preparation of (i-BuO)8PcRu(CO)2 (5). A 25 mL three-necked
flask equipped as that for the preparation of 2 was charged with 4
(0.109 g, 0.1 mmol), Ru3(CO)12 (0.128 g, 0.2 mmol), and 5 mL of
benzonitrile. The reaction mixture was refluxed at 190 °C for 1 h and
then cooled to room temperature. After the solvent was removed at
reduced pressure, the residue was subjected to silica gel column
H
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Hydrogen atoms were located by using the geometric method. Details
of crystal data, data collections, and structure refinements are
summarized in Table 4.
(15) Gloaguen, F.; Lawrence, J. D.; Schmidt, M.; Wilson, S. R.;
Rauchfuss, T. B. J. Am. Chem. Soc. 2001, 123, 12518−12527.
(16) Lyon, E. J.; Georgakaki, I. P.; Reibenspies, J. H.; Darensbourg,
M. Y. J. Am. Chem. Soc. 2001, 123, 3268−3278.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.5b01040.
(17) Razavet, M.; Davies, S. C.; Hughes, D. L.; Barclay, J. E.; Evans,
D. J.; Fairhurst, S. A.; Liu, X.; Pickett, C. J. Dalton Trans. 2003, 586−
595.
■
S
(18) (a) Harb, M. K.; Niksch, T.; Windhager, J.; Gorls, H.; Holze, R.;
̈
Lockett, L. T.; Okumura, N.; Evans, D. H.; Glass, R. S.; Lichtenberger,
D. L.; El-khateeb, M.; Weigand, W. Organometallics 2009, 28, 1039−
1048. (b) Almazahreh, L. R.; Imhof, W.; Talarmin, J.; Schollhammer,
Full tables of crystal data, atomic coordinates and
thermal parameters, and bond lengths and angles for 2,
4, 5, and 6 (CIF)
P.; Gorls, H.; El-khateeb, M.; Weigand, W. Dalton Trans. 2015, 44,
̈
7177−7189.
(19) Capon, J.-F.; Hassnaoui, S. E.; Gloaguen, F.; Schollhammer, P.;
Talarmin, J. Organometallics 2005, 24, 2020−2022.
(20) Adam, F. I.; Hogarth, G.; Richards, I.; Sanchez, B. E. Dalton
Trans. 2007, 2495−2498.
AUTHOR INFORMATION
Corresponding Author
*E-mail: lcsong@nankai.edu.cn.
■
(21) Lawrence, J. D.; Li, H.; Rauchfuss, T. B. Chem. Commun. 2001,
1482−1483.
(22) Song, L.-C.; Ge, J.-H.; Zhang, X.-G.; Liu, Y.; Hu, Q.-M. Eur. J.
Inorg. Chem. 2006, 2006, 3204−3210.
Notes
The authors declare no competing financial interest.
(23) Song, L.-C.; Yang, Z.-Y.; Bian, H.-Z.; Liu, Y.; Wang, H.-T.; Liu,
X.-F.; Hu, Q.-M. Organometallics 2005, 24, 6126−6135.
(24) Song, L.-C.; Yang, Z.-Y.; Hua, Y.-J.; Wang, H.-T.; Liu, Y.; Hu,
Q.-M. Organometallics 2007, 26, 2106−2110.
ACKNOWLEDGMENTS
■
We are grateful to the Ministry of Science and Technology of
China (973 Programs 2014CB845604 and 2011CB935902)
and the National Natural Science Foundation of China
(21132001, 21272122, and 21472095) for financial support.
(25) Daraosheh, A. Q.; Harb, M. K.; Windhager, J.; Gorls, H.; El-
̈
khateeb, M.; Weigand, W. Organometallics 2009, 28, 6275−6280.
(26) Harb, M. K.; Apfel, U.-P.; Sakamoto, T.; El-khateeb, M.;
Weigand, W. Eur. J. Inorg. Chem. 2011, 2011, 986−993.
(27) Heinekey, D. M. J. Organomet. Chem. 2009, 694, 2671−2680.
(28) (a) Song, L.-C.; Tang, M.-Y.; Su, F.-H.; Hu, Q.-M. Angew.
Chem., Int. Ed. 2006, 45, 1130−1133. (b) Song, L.-C.; Tang, M.-Y.;
Mei, S.-Z.; Huang, J.-H.; Hu, Q.-M. Organometallics 2007, 26, 1575−
1577. (c) Song, L.-C.; Wang, L.-X.; Jia, G.-J.; Li, Q.-L.; Ming, J.-B.
Organometallics 2012, 31, 5081−5088.
(29) Kluwer, A. M.; Kapre, R.; Hartl, F.; Lutz, M.; Spek, A. L.;
Brouwer, A. M.; van Leeuwen, P. W. N. M.; Reek, J. N. H. Proc. Natl.
Acad. Sci. U. S. A. 2009, 106, 10460−10465.
(30) Samuel, A. P. S.; Co, D. T.; Stern, C. L.; Wasielewski, M. R. J.
Am. Chem. Soc. 2010, 132, 8813−8815.
(31) Ott, S.; Kritikos, M.; Åkermark, B.; Sun, L. Angew. Chem. 2003,
115, 3407−3410; Angew. Chem., Int. Ed. 2003, 42, 3285−3288.
(32) Bottari, G.; de la Torre, G.; Guldi, D. M.; Torres, T. Chem. Rev.
2010, 110, 6768−6816.
(33) (a) Bottari, G.; Díaz, D. D.; Torres, T. J. Porphyrins
Phthalocyanines 2006, 10, 1083−1100. (b) de la Torre, G.;
Claessens, C. G.; Torres, T. Eur. J. Org. Chem. 2000, 2000, 2821−
2830.
(34) (a) Huang, J.-S.; Yu, G.-A.; Xie, J.; Wong, K.-M.; Zhu, N.; Che,
C.-M. Inorg. Chem. 2008, 47, 9166−9181. (b) Rawling, T.; Xiao, H.;
Lee, S.-T.; Colbran, S. B.; McDonagh, A. M. Inorg. Chem. 2007, 46,
2805−2813.
REFERENCES
■
(1) (a) Adams, M. W. W.; Stiefel, E. I. Science 1998, 282, 1842−1843.
(b) Cammack, R. Nature 1999, 397, 214−215. (c) Nicolet, Y.;
Cavazza, C.; Fontecilla-Camps, J. C. J. Inorg. Biochem. 2002, 91, 1−8.
(2) (a) Frey, M. ChemBioChem 2002, 3, 153−160. (b) Nicolet, Y.;
Lemon, B. J.; Fontecilla-Camps, J. C.; Peters, J. W. Trends Biochem. Sci.
2000, 25, 138−143. (c) Evans, D. J.; Pickett, C. J. Chem. Soc. Rev.
2003, 32, 268−275. (d) Cammack, R.; Frey, M.; Robson, R. In
Hydrogen as a Fuel: Learning from Nature; Taylor & Francis: London,
2001.
̀
(3) Nicolet, Y.; de Lacey, A. L.; Vernede, X.; Fernandez, V. M.;
Hatchikian, E. C.; Fontecilla-Camps, J. C. J. Am. Chem. Soc. 2001, 123,
1596−1601.
(4) Lemon, B. J.; Peters, J. W. Biochemistry 1999, 38, 12969−12973.
(5) Nicolet, Y.; Piras, C.; Legrand, P.; Hatchikian, C. E.; Fontecilla-
Camps, J. C. Structure 1999, 7, 13−23.
(6) Peters, J. W.; Lanzilotta, W. N.; Lemon, B. J.; Seefeldt, L. C.
Science 1998, 282, 1853−1858.
(7) Chen, Z.; Lemon, B. J.; Huang, S.; Swartz, D. J.; Peters, J. W.;
Bagley, K. A. Biochemistry 2002, 41, 2036−2043.
(8) De Lacey, A. L.; Stadler, C.; Cavazza, C.; Hatchikian, E. C.;
Fernandez, V. M. J. Am. Chem. Soc. 2000, 122, 11232−11233.
(9) Pierik, A. J.; Hulstein, M.; Hagen, W. R.; Albracht, S. P. J. Eur. J.
Biochem. 1998, 258, 572−578.
(35) Song, L.-C.; Li, C.-G.; Ge, J.-H.; Yang, Z.-Y.; Wang, H.-T.;
Zhang, J.; Hu, Q.-M. J. Inorg. Biochem. 2008, 102, 1973−1979.
(36) Lyon, E. J.; Georgakaki, I. P.; Reibenspies, J. H.; Darensbourg,
M. Y. Angew. Chem., Int. Ed. 1999, 38, 3178−3180.
(37) Rodríguez-Morgade, M. S.; Torres, T.; Atienza-Castellanos, C.;
Guldi, D. M. J. Am. Chem. Soc. 2006, 128, 15145−15154.
(38) Omiya, S.; Tsutsui, M.; Meyer, E. F., Jr.; Bernal, I.; Cullen, D. L.
Inorg. Chem. 1980, 19, 134−142.
(10) Adams, M. W. W. Biochim. Biophys. Acta, Bioenerg. 1990, 1020,
115−145.
(11) Pandey, A. S.; Harris, T. V.; Giles, L. J.; Peters, J. W.; Szilagyi, R.
K. J. Am. Chem. Soc. 2008, 130, 4533−4540.
(12) (a) Silakov, A.; Wenk, B.; Reijerse, E.; Lubitz, W. Phys. Chem.
Chem. Phys. 2009, 11, 6592−6599. (b) Berggren, G.; Adamska, A.;
Lambertz, C.; Simmons, T. R.; Esselborn, J.; Atta, M.; Gambarelli, S.;
Mouesca, J.-M.; Reijerse, E.; Lubitz, W.; Happe, T.; Artero, V.;
Fontecave, M. Nature 2013, 499, 66−69.
(13) Liu, T.; Wang, X.; Hoffmann, C.; DuBois, D. L.; Bullock, R. M.
Angew. Chem., Int. Ed. 2014, 53, 5300−5304.
(39) Gorbunova, Y. G.; Enakieva, Y. Y.; Sakharov, S. G.; Tsivadze, A.
Y. J. Porphyrins Phthalocyanines 2003, 7, 795−800.
(40) Kobayashi, N.; Fukuda, T.; Ueno, K.; Ogino, H. J. Am. Chem.
Soc. 2001, 123, 10740−10741.
(14) For reviews, see for example: (a) Song, L.-C. Acc. Chem. Res.
2005, 38, 21−28. (b) Capon, J.-F.; Gloaguen, F.; Schollhammer, P.;
Talarmin, J. Coord. Chem. Rev. 2005, 249, 1664−1676. (c) Lubitz, W.;
(41) Fukuda, T.; Homma, S.; Kobayashi, N. Chem. - Eur. J. 2005, 11,
5205−5216.
(42) Xu, H.; Ng, D. K. P. Inorg. Chem. 2008, 47, 7921−7927.
(43) Cheng, R.-J.; Lin, S.-H.; Mo, H.-M. Organometallics 1997, 16,
2121−2126.
Ogata, H.; Rudiger, O.; Reijerse, E. Chem. Rev. 2014, 114, 4081−4148.
̈
(d) Simmons, T. R.; Berggren, G.; Bacchi, M.; Fontecave, M.; Artero,
V. Coord. Chem. Rev. 2014, 270−271, 127−150.
I
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(44) Rawling, T.; McDonagh, A. Coord. Chem. Rev. 2007, 251, 1128−
1157.
(45) (a) Dudic, M.; Lhotak, P.; Kral, V.; Lang, K.; Stibor, I.
̌ ́ ́
Tetrahedron Lett. 1999, 40, 5949−5952. (b) Baskaran, D.; Mays, J. W.;
Zhang, X. P.; Bratcher, M. S. J. Am. Chem. Soc. 2005, 127, 6916−6917.
(46) Wang, F.; Wang, W.-G.; Wang, X.-J.; Wang, H.-Y.; Tung, C.-H.;
Wu, L.-Z. Angew. Chem., Int. Ed. 2011, 50, 3193−3197.
(47) Na, Y.; Wang, M.; Pan, J.; Zhang, P.; Åkermark, B.; Sun, L.
Inorg. Chem. 2008, 47, 2805−2810.
(48) Streich, D.; Astuti, Y.; Orlandi, M.; Schwartz, L.; Lomoth, R.;
Hamarstrom, L.; Ott, S. Chem. - Eur. J. 2010, 16, 60−63.
̈
(49) Yu, T.; Zeng, Y.; Chen, J.; Li, Y.-Y.; Yang, G.; Li, Y. Angew.
Chem., Int. Ed. 2013, 52, 5631−5635.
(50) Call, A.; Codola,
Eur. J. 2014, 20, 6171−6183.
̀ ́
Z.; Acuna-Pares, F.; Lloret-Fillol, J. Chem. -
̃
(51) Probst, B.; Kolano, C.; Hamm, P.; Alberto, R. Inorg. Chem.
2009, 48, 1836−1843.
(52) Rousset, E.; Chartrand, D.; Ciofini, I.; Marvaud, V.; Hanan, G. S.
Chem. Commun. 2015, 51, 9261−9264.
(53) Ozawa, H.; Haga, M.; Sakai, K. J. Am. Chem. Soc. 2006, 128,
4926−4927.
(54) Rau, S.; Walther, D.; Vos, J. G. Dalton Trans. 2007, 915−919.
(55) Fihri, A.; Artero, V.; Razavet, M.; Baffert, C.; Leibl, W.;
Fontecave, M. Angew. Chem., Int. Ed. 2008, 47, 564−567.
(56) Wang, W.-G.; Wang, F.; Wang, H.-Y.; Tung, C.-H.; Wu, L.-Z.
Dalton Trans. 2012, 41, 2420−2426.
(57) Figliola, C.; Male, L.; Horswell, S. L.; Grainger, R. S. Eur. J.
Inorg. Chem. 2015, 2015, 3146−3156.
(58) Song, L.-C.; Wang, L.-X.; Tang, M.-Y.; Li, C.-G.; Song, H.-B.;
Hu, Q.-M. Organometallics 2009, 28, 3834−3841.
(59) Song, L.-C.; Liu, X.-F.; Ming, J.-B.; Ge, J.-H.; Xie, Z.-J.; Hu, Q.-
M. Organometallics 2010, 29, 610−617.
(60) Seyferth, D.; Henderson, R. S.; Song, L.-C. J. Organomet. Chem.
1980, 192, C1−C5.
(61) CRYSTALCLEAR 1.3.6; Rigaku and Rigaku/MSC: The
Woodlands, TX, 2005.
(62) Sheldrick, G. M. SADABS, A Program for Empirical Absorption
Correction of Area Detector Data; University of Gottingen: Germany,
̈
1996.
(63) Sheldrick, G. M. SHELXS97, A Program for Crystal Structure
Solution; University of Gottingen: Germany, 1997.
̈
(64) Sheldrick, G. M. SHELXL97, A Program for Crystal Structure
Refinement; University of Gottingen: Germany, 1997.
̈
J
DOI: 10.1021/acs.organomet.5b01040
Organometallics XXXX, XXX, XXX−XXX