The N-acylated derivatives of parent complex [{(μ-SCH2) 2NH}Fe2(CO)6] as active site models of fe-only hydrogenases: Synthesis, characterization, and related properties

Article abstract of DOI:10.1002/ejic.200700845

A series of N-acylated diiron azadithiolate complexes as H-cluster models was synthesized and structurally characterized. Treatment of parent complex [{(μ-SCH₂)₂NH}Fe₂(CO)₆] (A) with 2-chloroacetic acid in the p

Full text of DOI:10.1002/ejic.200700845

FULL PAPER
DOI: 10.1002/ejic.200700845
The N-Acylated Derivatives of Parent Complex [{(µ-SCH2)2NH}Fe2(CO)6] as
Active Site Models of Fe-Only Hydrogenases: Synthesis, Characterization, and
Related Properties
Li-Cheng Song,*[a] Liang-Xing Wang,[a] Bang-Shao Yin,[a] Yu-Long Li,[a]
Xiao-Guang Zhang,[a] Yuan-Wei Zhang,[a] Xiang Luo,[a] and Qing-Mei Hu[a]
Keywords: Bioinorgnic chemistry / Iron / Electrochemistry / Hydrogenase models
A series of N-acylated diiron azadithiolate complexes as H-
cluster models was synthesized and structurally charac-
terized. Treatment of parent complex [{(µ-SCH2)2NH}-
Fe2(CO)6] (A) with 2-chloroacetic acid in the presence of di-
cyclohexylcarbodiimide or with 2-chloroacetyl chloride in the
presence of Et3N gave N-chloroacetyl complex [{(µ-SCH2)2-
NC(O)CH2Cl}Fe2(CO)6] (1). Further treatment of 1 with
MeC(O)SK afforded N-acetylthioacetyl complex [{(µ-SCH2)2-
NC(O)CH2SC(O)Me}Fe2(CO)6] (2). N-Ethoxylcarbonylacetyl
complex [{(µ-SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3) and N-
heterocyclic complexes [{(µ-SCH2)2NC(O)C4H3Y-2}Fe2(CO)6]
(4, Y = O; 5, Y = S) were produced by reactions of A with
EtO2CCH2C(O)Cl, 2-furancarbonyl chloride, and 2-thio-
phenecarbonyl chloride in the presence of pyridine or Et3N.
Similarly, N-malonyl complex [{Fe2(CO)6(µ-SCH2)2NC-
(O)}2CH2] (6) and N-carbonylbenzaldehyde complex [{(µ-
SCH2)2NC(O)C6H4CHO-p}Fe2(CO)6] (7) could be obtained
by reaction of A with malonyl dichloride in the presence of
pyridine and with p-CHOC6H4C(O)Cl in the presence of
Et3N. More interestingly, further reaction of 7 with PhCHO
and pyrrole in a 1:3:4 molar ratio in the presence of BF3·OEt2
followed by p-chloranil yielded the first light-driven type of
model complex containing an N-carbonylphenylporphyrin
moiety [{(µ-SCH2)2NC(O)(TPP)}Fe2(CO)6] (8, TPP
= tet-
raphenylporphyrin group). Whereas the molecular structures
of 2, 5, and 7 were established by X-ray crystallography, the
electrochemical properties of 2–5 as well as the proton re-
duction to hydrogen gas catalyzed by 2 and 3 were studied
by CV techniques.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
be used as starting materials to make complicated models,
such as light-driven[20] and whole H-cluster models[21] by
functional transformation reactions. Herein we report the
synthesis and structural characterization of a series of N-
functionalized ADT-type models. In addition, the related
electrochemical and catalytic properties for some of the
newly synthesized models are also described.
Introduction
Fe-only hydrogenases have received special attention in
recent years, mainly due to their unique structure and par-
ticularly their unusual capacity to catalyze proton reduction
to the “clean” and highly efficient fuel: hydrogen gas.[1] Pro-
tein crystallographic[2–4] and FTIR spectroscopic[5–7] studies
revealed that the active site of Fe-only hydrogenases, the
so-called H-cluster, consists of a cubane-like [Fe4S4] cluster
linked to a butterfly [Fe2S2] cluster through the S atom of
a cysteinyl bridge. In the [Fe2S2] cluster, the two iron atoms
are bridged by three-light-atom (possibly carbon or any
combination of C, N, and O)-containing dithiolate ligands,
and they are also coordinated by CO and CN– ligands (Fig-
ure 1). This well-elucidated structure has greatly inspired
chemists to design and synthesize a variety of structural
and functional models for the active site of Fe-only hydro-
genases.[8–19] As H-cluster models, the N-functionalized di-
iron azadithiolate (ADT) complexes are of particular inter-
est, as they are not only simple models, but they can also
Figure 1. Basic structure of the H-cluster (X = CH2, NH, or O).
Results and Discussion
Synthesis and Characterization of Model Complexes [{(µ-
SCH2)2NC(O)CH2Cl}Fe2(CO)6] (1) and [{(µ-SCH2)2-
NC(O)CH2SC(O)Me}Fe2(CO)6] (2)
[a] Department of Chemistry, State Key Laboratory of Elemento-
Organic Chemistry, Nankai University,
Tianjin 300071, China
N-Functionalized ADT-type model complexes 1 and 2
could be prepared conveniently starting from parent com-
Fax: +86-22-23504853
E-mail: lcsong@nankai.edu.cn
Eur. J. Inorg. Chem. 2008, 291–297
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
291

L.-C. Song et al.
FULL PAPER
plex [{(µ-SCH2)2NH}Fe2(CO)6] (A).[22] Treatment of A with Both the Fe1 and Fe2 atoms adopt the expected square-
2-chloroacetic acid in the presence of the carboxylic group pyramidal geometry and the Fe1–Fe2 bond length
activating reagent dicyclohexylcarbodiimide (DCC) gave N- (2.5062 Å) is close to the corresponding lengths of similar
chloroacetyl complex 1 in 53% yield; 1 was also prepared diiron dithiolate complexes.[14–19,23]
in a much higher yield (86%) by treatment of A with 2-
Table 1. Selected bond lengths and angles for 2.
chloroacetyl chloride in the presence of Et3N. Further treat-
ment of 1 with MeC(O)SK afforded corresponding N-func-
tionalized complex 2 in 56% yield (Scheme 1).
Bond lengths [Å]
Fe1–S1
Fe1–S2
Fe1–Fe2
Fe2–S1
2.2598(15)
Fe2–S2
S3–C10
S3–C11
C9–O7
2.2653(15)
1.831(5)
1.741(7)
1.204(5)
2.2597(15)
2.5062(10)
2.2592(15)
Bond angles [°]
S1–Fe2–Fe1
S2–Fe1–S1
S2–Fe1–Fe2
S1–Fe1–Fe2
S1–Fe2–S2
85.06(5)
56.47(4)
56.31(4)
84.94(5)
56.33(4)
56.26(4)
67.37(4)
67.26(4)
S2–Fe2–Fe1
Fe2–S1–Fe1
Fe1–S2–Fe2
Synthesis and Characterization of Model Complexes [{(µ-
SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3), [{(µ-SCH2)2NC-
(O)C4H3Y-2}Fe2(CO)6] (4, Y = O; 5, Y = S) and
[{Fe2(CO)6(µ-SCH2)2NC(O)}2CH2] (6)
Scheme 1. (a) ClCH2CO2H, DCC, CH2Cl2, 0 °C to room temp.;
(b) ClCH2C(O)Cl, Et3N, THF, 0 °C to room temp.; (c) MeC(O)-
SK, THF, MeOH, 0 °C to room temp.
Similarly, N-functionalized ADT-type model complexes
3–6 could also be prepared readily from parent complex A.
Treatment of A with EtO2CCH2C(O)Cl, 2-furancarbonyl,
or 2-thiophenecarbonyl chloride in the presence of pyridine
or Et3N produced diiron complexes 3–5 in 52–79% yields,
whereas the reaction of A with malonyl dichloride in the
presence of pyridine resulted in the formation of tetrairon
complex 6 in 53% yield (Scheme 2).
Compounds 1 and 2 are air-stable red solids, which were
characterized by elemental analysis and spectroscopy. For
instance, the IR spectra of 1 and 2 showed four absorption
bands in the region 2083–1969 cm–1 for their terminal car-
bonyl groups, whereas they displayed one or two additional
absorption bands in the range 1698–1676 cm–1 for their es-
1
ter and amide carbonyl groups. The H NMR spectra of 1
and 2 exhibited one singlet at δ = 4.12 and 4.13 ppm for the
two equivalent protons in each of their two NCH2S groups,
respectively.
The molecular structure of 2 was unequivocally con-
firmed by X-ray diffraction analysis (Figure 2, Table 1). As
shown in Figure 2, this molecule has an acetylthioacetyl
functionality, which is axially attached to the N1 atom of
the two fused six-membered rings: a chair-shaped Fe1–S1–
C7–N1–C8–S2 and a boat-shaped Fe2–S1–C7–N1–C8–S2.
Scheme 2. (a) EtO2CCH2C(O)Cl, pyridine, CH2Cl2, 0 °C to room
temp.; (b) C4H3YC(O)Cl, Et3N, CH2Cl2, room temp.; (c) ClC(O)-
CH2C(O)Cl, pyridine, CH2Cl2, 0 °C to room temp.
Compounds 3–6 are also air-stable red solids, which were
fully characterized by elemental analysis and IR and 1H
NMR spectroscopy. The IR spectra of 3–6 exhibited four
absorption bands in the region 2082–1972 cm–1 for their
terminal carbonyl groups. In addition, 3 displayed two ab-
sorption bands at 1663 and 1753 cm–1 for its amide and
ester carbonyl groups, whereas 4–6 showed one absorption
band in the range 1621–1660 cm–1 for their amide carbonyl
Figure 2. Molecular structure of 2 with 30% probability level ellip-
soids.
1
groups. The H NMR spectra of 3–6 showed one or two
292
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 291–297

N-Acylated Derivatives of [{(µ-SCH2)2NH}Fe2(CO)6]
singlets at ca. 4.2 ppm for the two equivalent protons in Et3N gave rise to complex 7 in 52% yield; further treatment
each of their NCH2S groups. These chemical values are of 7 with benzaldehyde and pyrrole in a 1:3:4 molar ratio
shifted downfield by ca. 0.5 ppm relative to that of parent in the presence of catalytic BF3·OEt2 followed by the oxi-
complex A,[22] obviously due to the stronger electron-with- dant p-chloranil[20,24] resulted in the formation of complex
drawing effects of their N-functionalities.
8 in 20% yield along with tetraphenylporphyrin (TPPH) in
X-ray crystallographic analysis revealed that complex 5 18% yield (Scheme 3).
(Figure 3, Table 2) contains a thiophenecarbonyl group at-
tached to the N1 atom by the common axial bond of the
two fused six-membered Fe2–S2–C8–N1–C7–S1 and Fe1–
S2–C8–N1–C7–S1 rings. In addition, the Fe1–Fe2 bond
length of 5 is 2.5068 Å, which is nearly the same as that of
2, but it is slightly shorter than the corresponding lengths
(2.55–2.62 Å) in the natural enzymes.[2–4] The dihedral an-
gle between the thiophene ring and the C10–C9–O7 plane
is 28.5°. This means that some p–π conjugation between
these two parts is present, which may explain why the
double bond between C9 and O7 (1.226 Å) in this complex
is slightly longer than that between C9 and O7 (1.204 Å) in
complex 2.
Scheme 3. (a) p-CHOC6H4C(O)Cl, Et3N, CH2Cl2, 0 °C to room
temp.; (b) PhCHO, pyrrole, BF3·Et2O, CH2Cl2, room temp.; (c) p-
chloranil, CH2Cl2, reflux.
Whereas 7 is an air-stable red solid, 8 is an air-stable
purple-red solid. They were all characterized by elemental
analysis and IR and 1H NMR spectroscopic techniques.
For example, the IR spectrum of 7 displayed four absorp-
tion bands in the range 2077–1985 cm–1 for its terminal car-
bonyl groups and two absorption bands at 1695 and
1656 cm–1 for its formyl and amide carbonyl groups,
whereas 8 showed three absorption bands in the range
2077–2000 cm–1 for its terminal carbonyl groups, one ab-
sorption band at 1653 cm–1 for its amide carbonyl group,
and three absorption bands at 1558, 1473, and 1350 cm–1
for the skeleton vibrations of the pyrrole rings in the por-
Figure 3. Molecular structure of 5 with 30% probability level ellip-
soids.
Table 2. Selected bond lengths and angles for 5.
Bond lengths [Å]
Fe1–S1
Fe1–S2
Fe1–Fe2
Fe2–S1
2.2524(10)
2.2654(9)
2.5068(8)
2.2641(10)
Fe2–S2
N1–C9
N1–C8
C9–O7
2.2595(9)
1.369(4)
1.436(4)
1.226(4)
1
phyrin macrocycle.[25] In addition, the H NMR spectrum
of 7 exhibited one singlet at δ = 4.32 ppm and one singlet
at δ = 4.11 ppm for the two protons in each of its two
NCH2S groups, and another singlet at δ = 10.08 ppm for
the proton in its formyl group, whereas 8 displayed one sin-
glet at δ = 4.53 ppm for the two protons in each of its two
NCH2S groups and another singlet at δ = –2.79 ppm for
the protons attached to N atoms in the porphyrin moiety.[26]
X-ray crystallographic analysis revealed that the struc-
ture of 7 (Figure 4, Table 3) resembles the above-described
structures of 2 and 5; compound 7 is a functionalized azadi-
thiolate ligand that is bridged between the Fe1 and Fe2
Bond angles [°]
S1–Fe1–S2
S1–Fe1–Fe2
S2–Fe1–Fe2
S2–Fe2–S1
84.88(3)
56.51(3)
56.25(3)
84.75(3)
S2–Fe2–Fe1
56.47(2)
56.06(3)
67.42(3)
118.9(3)
S1–Fe2–Fe1
Fe1–S1–Fe2
C9–N1–C7
Synthesis and Characterization of Model Complexes
[{(µ-SCH2)2NC(O)C6H4CHO-p}Fe2(CO)6] (7) and [{(µ-
SCH2)2NC(O)(TPP)}Fe2(CO)6] (8)
Interestingly, on the basis of synthesizing N-benzalde- atoms to form two fused six-membered rings: a chair-
hyde complex 7, the first light-driven type of model com- shaped Fe1–S1–C8–N1–C7–S2 and a boat-shaped Fe2–S1–
plex containing an N-carbonylphenylporphyrin moiety, C8–N1–C7–S2. In addition, the N-functionality of 7,
namely 8, was successfully synthesized. Treatment of com- namely the carbonylbenzaldehyde group, is connected to
plex A with p-formylbenzoyl chloride in the presence of the bridgehead N1 atom by an axial bond.
Eur. J. Inorg. Chem. 2008, 291–297
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
293

L.-C. Song et al.
FULL PAPER
Table 4. Electrochemical data of 2–5.[a]
Compound
Epc [V]
Epc [V]
Epa [V]
2
3
4
5
–1.49
–1.51
–1.54
–1.52
–1.96
–2.00
–1.99
–1.97
+0.86
+0.87
+0.81
+0.82
[a] All potentials are versus Fc/Fc+ in 0.1  nBu4NPF6/MeCN.
Figure 4. Molecular structure of 7 with 30% probability level ellip-
soids.
Table 3. Selected bond lengths and angles for 7.
Bond lengths [Å]
Figure 5. Cyclic voltammogram of 2 (1.0 m) in 0.1  nBu4NPF6/
MeCN at a scan rate of 100 mVs–1.
Fe1–S1
Fe1–S2
Fe1–Fe2
Fe2–S1
2.2517(8)
2.2561(8)
2.5265(6)
2.2541(8)
Fe2–S2
N1–C9
N1–C8
C9–O7
2.2490(8)
1.374(3)
1.436(3)
1.223(3)
Further cyclic voltammetric studies revealed that 2 and
3 have the ability to undergo proton reduction to hydrogen
gas in the presence of weak acid HOAc (pKa = 22.6 in
MeCN). The cyclic voltammogram of 2 with HOAc is pre-
sented in Figure 6. It shows that when the first 5 m of
HOAc is added, the original first reduction peak at –1.49 V
slightly increases but does not continue to increase with se-
quential addition of the acid. However, in contrast to this,
when the first 5 m of HOAc is added, the original second
reduction peak at –1.96 V markedly increases and continues
to increase with sequential addition of the acid. Such obser-
vations are typical of an electrochemical catalytic pro-
cess.[27–30] The bulk electrolysis of HOAc (25 m) catalyzed
Bond angles [°]
S1–Fe1–S2
S1–Fe1–Fe2
S2–Fe1–Fe2
S2–Fe2–S1
S2–Fe2–Fe1
84.89(3)
55.94(2)
55.76(2)
85.00(3)
56.02(2)
Fe1–S1–Fe2
68.21(3)
55.85(2)
121.4(3)
124.1(2)
115.4(2)
S1–Fe2–Fe1
O7–C9–C10
C9–N1–C7
C8–N1–C7
Electrochemistry of Model Complexes 2–5
The electrochemical behavior of 2–5 was investigated by
cyclic voltammetry in MeCN under a N2 or CO atmo-
sphere. Whereas Table 4 lists the electrochemical data of 2–
5, Figure 5 shows the cyclic voltammogram of 2. These
complexes each display one quasi-reversible reduction, one
irreversible reduction, and one irreversible oxidation. All
the reductions and oxidations are one-electron processes
(supported by bulk electrolysis), which can be assigned to
reduction of FeIFeI to FeIFe0, further reduction of FeIFe0
to Fe0Fe0, and oxidation of FeIFeI to FeIFeII, respectively.
It is noteworthy that the reduction and oxidation potentials
of 2–5 are more positive than those corresponding to the
methoxyphenyl-functionalized complex [{(µ-SCH2)2NC6-
H4OMe-p}Fe2(CO)6],[15] obviously due to the fact that the
N-functionalities of 2–5 are stronger electron-withdrawing
groups than the N-methoxyphenyl group. Such electro-
chemical behavior of 2–5 is similar to that of the previously
reported diiron dithiolate model complexes.[27,28]
Figure 6. Cyclic voltammogram of 2 (1.0 m) with HOAc (0–
25 m) in 0.1  nBu4NPF6/MeCN at a scan rate of 100 mVs–1.
294
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 291–297

N-Acylated Derivatives of [{(µ-SCH2)2NH}Fe2(CO)6]
Bruker Avance 300 or a Varian Mercury Plus 400 spectrometer.
Elemental analyses were performed with an Elementar Vario EL
analyzer. Melting points were determined with a Yanaco MP-500
apparatus and are uncorrected.
by 2 (0.50 m) in MeCN at –2.34 V indicated a total of
12.3 F per mol of 2 to be passed during half an hour. This
corresponds to 6.1 turnovers. Gas chromatography showed
that the yield of hydrogen gas was about 90%.
On the basis of the previously reported similar cases[27–30]
and the electrochemical observations described above, a
2E2C (E = electrochemical, C = chemical) mechanism
could be proposed to account for this electrocatalytic pro-
cess. As shown in Scheme 4, complex 2 is first reduced at
–1.49 V to give monoanion 2–. Then, 2– is further reduced
at –1.96 V to generate dianion 22–. After electron-rich di-
anion 22– is protonated by HOAc to form the Fe–H species
2H–, it accepts an additional proton from HOAc to com-
plete the catalytic cycle with H2 evolution. Although this
suggested mechanism is essentially the same as that sug-
gested for the corresponding process catalyzed by complex
[(µ-SCH2)2NC6H4OMe-p]Fe2(CO)6],[15] the first and second
reduction potentials of 2 are shifted positively by 120 and
140 mV, respectively, relative to those corresponding to the
above-mentioned complex. It follows that the presence of
stronger electron-withdrawing groups at the bridgehead N
atom could lower the reduction potentials of the two Fe
atoms of the diiron subsite and thus make the proton re-
duction to hydrogen gas much easier.
[{(µ-SCH2)2NC(O)CH2Cl}Fe2(CO)6] (1)
Method 1: A solution of DCC (0.093 g, 0.45 mmol) in CH2Cl2
(5 mL) was added to a stirred and cooled (0 °C) solution of com-
plex A (0.176 g, 0.45 mmol) and ClCH2CO2H (0.043 g, 0.45 mmol)
in CH2Cl2 (20 mL). After the mixture was stirred at 0 °C for 1 h
and at room temperature for 3 h, the solvent was removed in vacuo,
and the residue was subjected to TLC separation (CH2Cl2/petro-
leum ether, 1:1). From the main red band, 1 was obtained as a
red solid (0.110 g, 53%). M.p. 105–106 °C. 1H NMR (400 MHz,
CDCl3): δ = 4.12 (s, 4 H, 2 NCH2S), 4.08 (s, 2 H, CH2Cl) ppm.
IR (KBr disk): ν = 2083 (s), 2035 (vs), 1996 (vs), 1969 (vs) CϵO,
˜
1677 (s) NC=O cm–1. C10H6ClFe2NO7S2 (463.44): calcd. C 25.92,
H 1.30, N 3.02; found C 26.00, H 1.48, N 3.09.
Method 2: To a stirred red solution of complex A (0.387 g,
1.00 mmol) in THF (20 mL) at 0 °C was added ClC(O)CH2Cl
(0.16 mL, 2.00 mmol) and Et3N (0.28 mL, 2.00 mmol). After the
mixture was stirred at 0 °C for 0.5 h and at room temperature for
2 h, the same work-up as Method (i) was applied to give 1 (0.398 g,
86%).
[{(µ-SCH2)2NC(O)CH2SC(O)Me}Fe2(CO)6] (2): A stirred red solu-
tion of 1 (0.232 g, 0.50 mmol) in THF (20 mL) and MeOH (10 mL)
was cooled to 0 °C and then MeC(O)SK (0.057 g, 0.50 mmol) was
added. The mixture was warmed to room temperature and then
stirred at this temperature for 3 h. The same work-up as that for
the preparation of 1 was employed to afford 2 as a red solid
1
(0.141 g, 56%). M.p. 127–129 °C. H NMR (400 MHz, CDCl3): δ
= 4.13 (s, 4 H, 2 NCH2S), 3.81 (s, 2 H, COCH2S), 2.40 (s, 3 H,
CH ) ppm. IR (KBr disk): ν = 2074 (s), 2039 (vs), 2007 (vs), 1989
˜
3
(vs) CϵO, 1698 (s) SC=O, 1676 (s) NC=O cm–1. C12H9Fe2NO8S3
(503.08): calcd. C 28.65, H 1.80, N 2.78; found C 28.72, H 1.91, N
2.89.
[{(µ-SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3): A red solution of
complex A (0.078 g, 0.20 mmol) and pyridine (0.02 mL, 0.25 mmol)
in CH2Cl2 (15 mL) was cooled to 0 °C and then ClC(O)CH2CO2Et
(0.06 mL, 0.50 mmol) was added. After the mixture was stirred at
0 °C for 15 min, it was warmed to room temperature and then
stirred at this temperature for 3 h. Volatiles were removed in vacuo
and the residue was subjected to TLC separation (CH2Cl2/petro-
leum ether, 3:1). From the main band, 3 was obtained as a red solid
Scheme 4. Proposed 2E2C mechanism for H2 evolution catalyzed
by 2. All terminal carbonyl groups and the N-functionalities are
omitted for clarity.
1
(0.081 g, 80%). M.p. 154–156 °C. H NMR (400 MHz, CDCl3): δ
= 4.17 (s, 4 H, 2 NCH2S), 4.07 (s, 2 H, OCH2CH3), 3.49 (s, 2 H,
Experimental Section
COCH CO), 1.26 (s, 3 H, CH ) ppm. IR (KBr disk): ν = 2080 (s),
˜
2
3
2037 (vs), 2004 (vs), 1984 (vs) CϵO, 1753 (s) OC=O, 1663 (s)
NC=O cm–1. C13H11Fe2NO9S2 (501.10): calcd. C 31.16, H 2.21, N
2.80; found C 31.29, H 2.28, N 2.85.
General Comments: All reactions were carried out by using stan-
dard Schlenk and vacuum-line techniques under a N2 atmosphere.
Dichloromethane was distilled from CaH2, THF from sodium/
benzophenone ketyl, and methanol from Mg powders under a N2 [{(µ-SCH2)2NC(O)C4H3O-2}Fe2(CO)6] (4): A red solution of A
atmosphere. 2-Chloroacetic acid, 2-chloroacetyl chloride, MeC(O)-
SK, N,NЈ-dicyclohexylcarbodiimide (DCC), PhCHO, pyrrole,
BF3·OEt2, and 2,3,5,6-tetrachlorobenzoquinone (p-chloranil) were
available from commercial suppliers and used without further puri-
fication. [{(µ-SCH2)2NH}Fe2(CO)6] (A),[22] furancarbonyl chlo-
ride,[31] thiophenecarbonyl chloride,[32] malonyl dichloride,[33]
EtO2CCH2C(O)Cl,[34] and p-CHOC6H4C(O)Cl[35a,35b] were pre-
pared according to literature procedures. Preparative TLC was car-
ried out on glass plates (26ϫ20ϫ0.25 cm) coated with silica gel H
(10–40 µm). IR spectra were recorded with a Bruker Vector 22 in-
(0.230 g, 0.60 mmol), 2-C4H3OC(O)Cl (0.45 mL, 4.57 mmol), and
Et3N (1.0 mL, 7.15 mmol) in CH2Cl2 (10 mL) was stirred at room
temperature for 5 h. After the mixture was evaporated to dryness
under vacuum, the residue was subjected to TLC separation (ace-
tone/petroleum ether, 1:2). From the main red band, 4 was obtained
as a red solid (0.202 g, 70%). M.p. 109–111 °C. 1H NMR
(300 MHz, CDCl3): δ = 7.50, 7.13, 6.49 (3 s, 3 H, C4H3O), 4.44,
4.21 (2 s, 4 H, 2 NCH S) ppm. IR (KBr disk): ν = 2082 (s), 2034
˜
2
(vs), 1994 (vs), 1976 (vs) CϵO, 1639 (s) NC=O cm–1.
C13H7Fe2NO8S2 (481.02): calcd. C 32.46, H 1.47, N 2.95; found C
32.67, H 1.64, N 2.91.
1
frared spectrophotometer. H NMR spectra were obtained with a
Eur. J. Inorg. Chem. 2008, 291–297
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
295

L.-C. Song et al.
[{(µ-SCH2)2NC(O)C4H3S-2}Fe2(CO)6] (5): The same procedure as fractometer. Data were collected at room temperature by using a
FULL PAPER
that for the preparation of 4 was followed. From complex A
(0.200 g, 0.52 mmol) and 2-C4H3SC(O)Cl (0.45 mL, 4.21 mmol), 5
was obtained as a red solid (0.135 g, 52%). M.p. 118–120 °C. 1H
NMR (300 MHz, CDCl3): δ = 7.56, 7.42, 7.12 (3 s, 3 H, C4H3S),
graphite monochromator with Mo-Kα radiation (λ = 0.71073 Å) in
the ω-φ scanning mode. Absorption correction was performed by
the SADABS program.[36] The structures were solved by direct
methods by using the SHELXS-97 program[37] and refined by full-
matrix least-squares techniques (SHELXL-97)[38] on F2. Hydrogen
atoms were located by using the geometric method. Details of crys-
tal data, data collections, and structure refinements are summa-
rized in Table 5.
4.34 (s, 4 H, 2 NCH S) ppm. IR (KBr disk): ν = 2081 (s), 2051 (vs),
˜
2
2000 (vs), 1972 (vs) CϵO, 1621 (s) NC=O cm–1. C13H7Fe2NO7S3
(497.08): calcd. C 31.41, H 1.42, N 2.82; found C 31.39, H 1.56, N
2.92.
[{(µ-SCH2)2NC(O)Fe2(CO)6}2CH2] (6): A red solution of complex
A (0.116 g, 0.30 mmol) and pyridine (0.03 mL, 0.37 mmol) in
CH2Cl2 (15 mL) was cooled to 0 °C and then malonyl dichloride
(0.015 mL, 0.15 mmol) was added. The mixture was stirred at 0 °C
for 15 min and then at room temperature for 4 h. The solvent was
removed under reduced pressure, and the residue was subjected to
TLC separation (CH2Cl2/petroleum ether, 2:1) to afford 6 as a red
Table 5. Crystal data and structure refinement details for 2, 5 and
7.
2
5
7
Formula
C12H9Fe2NO8S3 C13H7Fe2NO7S3 C16H9Fe2NO8S2
Mr [gmol–1
Crystal system
Space group
a [Å]
b [Å]
c [Å]
]
503.08
monoclinic
P21/c
14.348(3)
10.341(2)
12.883(2)
90
497.08
monoclinic
P21/n
16.057 (3)
6.7670(13)
16.874(3)
90
519.06
monoclinic
P21/c
14.569(3)
11.792(2)
11.697(2)
90
1
solid (0.067 g, 53%). M.p. Ͼ300 °C. H NMR (400 MHz, CDCl3):
δ = 4.22, 4.07 (2 s, 8 H, 4 NCH2S), 3.55 (s, 2 H, COCH2) ppm. IR
(KBr disk): ν = 2078 (s), 2039 (vs), 2011 (vs), 1994 (vs) CϵO, 1660
˜
(s) NC=O cm–1. C19H10Fe4N2O16S4 (841.79): calcd. C 27.11, H
1.20, N 3.33; found C 27.09, H 1.18, N 3.32.
α [°]
[{(µ-SCH2)2NC(O)C6H4CHO-p}Fe2(CO)6] (7): A solution of com-
plex A (0.314 g, 0.80 mmol) and Et3N (0.2 mL, 1.43 mmol) in
CH2Cl2 (10 mL) was cooled to 0 °C and then p-CHOC6H4C(O)Cl
(0.158 g, 0.94 mmol) was added. The mixture was stirred at 0 °C for
0.5 h and at room temperature for 2 h until TLC showed complete
consumption of A. The solvent was removed in vacuo, and the
residue was subjected to TLC separation (CH2Cl2/petroleum ether,
1:1). From the main red band, 7 was obtained as a red solid
β [°]
96.259(4)
90
1900.1(6)
4
1.759
1.894
100.225(3)
90
1804.4(6)
4
1.830
1.990
104.355(3)
90
1946.9(6)
4
1.771
1.749
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3
]
µ [mm–1
]
F(000)
Index ranges
1008
992
1040
–17ՅhՅ17
–8ՅkՅ12
–16ՅlՅ15
10522
–20ՅhՅ19
–6ՅkՅ8
–21ՅlՅ15
9779
–16ՅhՅ18
–14ՅkՅ13
–14ՅlՅ13
10740
1
(0.218 g, 52%). M.p. 206–207 °C. H NMR (400 MHz, CDCl3): δ
= 10.08 (s, 1 H, CHO), 7.99, 7.97, 7.63, 7.61 (AB quartet, 4 H,
Reflections collected
C H ), 4.32, 4.11 (2 s, 4 H, 2 NCH S) ppm. IR (KBr disk): ν =
˜
Independent reflections 3879
3697
3967
6
4
2
2077 (s), 2038 (vs), 2006 (vs), 1985 (vs) CϵO, 1695 (s) HC=O, 1656
(s) NC=O cm–1. C16H9Fe2NO8S2 (519.06): calcd. C 37.02, H 1.75,
N 2.70; found C 36.99, H 1.70, N 2.67.
2θmax [°]
R
Rw
52.88
0.0489
0.0874
1.029
52.84
0.0350
0.0762
1.000
52.76
0.0309
0.0638
1.024
Goodness-of-fit
Largest diff. peak/hole
[{(µ-SCH2)2NC(O)(TPP)}Fe2(CO)6] (8): A solution of 7 (0.376 g,
0.72 mmol), pyrrole (0.20 mL, 2.88 mmol), PhCHO (0.246 mL,
2.16 mmol), and BF3·OEt2 (0.036 mL, 0.29 mmol) in CH2Cl2
(288 mL) was stirred in the dark at room temperature for 16 h to
give a brown-red solution. To this solution was added p-chloranil
(0.708 g, 2.88 mmol), and the new mixture was heated at reflux for
2 h to give a brown-black solution. Solvent was removed under
reduced pressure, and the residue was subjected to flash column
chromatography (Al2O3, CH2Cl2). The eluate was reduced to a suit-
able volume for TLC separation (CH2Cl2/petroleum ether, 6:1) as
eluent. From the first band, tetraphenylporphyrin (TPPH; 0.081g,
18%) was obtained as a purple solid, which was identified by com-
0.585/–0.590
0.311/–0.346
0.301/–0.303
[eÅ–3
]
CCDC-656305, -656306, and -656307 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Electrochemistry: Acetonitrile (Fisher Chemicals, HPLC grade) was
used for electrochemistry assays. A solution of 0.1  nBu4NPF6 in
MeCN was used as the electrolyte in all cyclic voltammetric experi-
ments. Electrochemical measurements were made with a BAS Epsi-
lon potentiostat. All voltammograms were obtained in a three-elec-
trode cell with a 3-mm diameter glassy carbon working electrode,
a platinum counter electrode, and an Ag/Ag+ (0.01  AgNO3/0.1
 nBu4NPF6 in MeCN) reference electrode under a N2 or CO at-
mosphere. The working electrode was polished with 0.05-µm alu-
mina paste and sonicated in water for 10 min prior to use. Bulk
electrolysis was run on a vitreous carbon rod (ca. 3 cm2) in a two-
compartment, gastight, H-type electrolysis cell containing ca.
20 mL of MeCN. All potentials are quoted against the ferrocene/
ferrocenium (Fc/Fc+) potential. Gas chromatography was per-
formed with a Shimadzu gas chromatograph GC-9A under isother-
mal conditions with nitrogen as a carrier gas and a thermal conduc-
tivity detector.
1
parison of its IR and H NMR spectra with those of an authentic
sample.[25,26] From the second purple band, complex 8 was ob-
tained as a purple-red solid (0.146 g, 20%). M.p. Ͼ300 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.88–8.81 (m, 8 H, pyrrole rings),
8.33, 8.31 (2 s, 2 H, 2 m-H of C6H4CO), 8.22, 8.21 (2 s, 6 H, 6 o-
H of C6H5), 7.87,7.85 (2 s, 2 H, 2 o-H of C6H4CO), 7.77, 7.76 (2
s, 9 H, 6 m-H of C6H5, 3 p-H of C6H5), 4.53 (s, 4 H, 2 NCH2S),
–2.79 (s, 2 H, 2 NH) ppm. IR (KBr disk): ν = 2077 (s), 2037 (vs),
˜
2000 (vs) CϵO, 1653 (s) NC=O cm–1. C53H33Fe2N5O7S2 (1027.69):
calcd. C 61.94, H 3.24, N 6.81; found C 62.04, H 3.29, N 6.60.
X-ray Structure Determinations of 2, 5, and 7: Single crystals of 2,
5, and 7 suitable for X-ray diffraction analyses were grown by slow
evaporation of a CH2Cl2/hexane solution of 2 or 5 at –10 °C and
a CH2Cl2 solution of 7 at room temperature. A single crystal of 2,
5, or 7 was mounted on a Bruker SMART 1000 automated dif-
296
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 291–297

N-Acylated Derivatives of [{(µ-SCH2)2NH}Fe2(CO)6]
[19] L.-C. Song, Z.-Y. Yang, Y.-J. Hua, H.-T. Wang, Y. Liu, Q.-M.
Hu, Organometallics 2007, 26, 2106–2110.
Acknowledgments
[20] a) L.-C. Song, M.-Y. Tang, F.-H. Su, Q.-M. Hu, Angew. Chem.
Int. Ed. 2006, 45, 1130–1133; b) L.-C. Song, M.-Y. Tang, S.-Z.
Mei, J.-H. Huang, Q.-M. Hu, Organometallics 2007, 26, 1575–
1577.
[21] C. Tard, X. Liu, S. K. Ibrahim, M. Bruschi, L. De Gioia, S. C.
Davies, X. Yang, L.-S. Wang, G. Sawers, C. J. Pickett, Nature
2005, 433, 610–613.
[22] H. Li, T. B. Rauchfuss, J. Am. Chem. Soc. 2002, 124, 726–727.
[23] a) J. D. Lawrence, H. Li, T. B. Rauchfuss, M. Bénard, M.-M.
Rohmer, Angew. Chem. Int. Ed. 2001, 40, 1768–1771; b) E. J.
Lyon, I. P. Georgakaki, J. H. Reibenspies, M. Y. Darensbourg,
Angew. Chem. Int. Ed. 1999, 38, 3178–3180.
[24] J. S. Lindsey, I. C. Schreiman, H. C. Hsu, P. C. Kearney, A. M.
Marguerettaz, J. Org. Chem. 1987, 52, 827–836.
We are grateful to the National Natural Science Foundation of
China and the Specialized Research Fund for the Doctoral Pro-
gram of Higher Education of China for financial support of this
work.
[1] a) M. Y. Darensbourg, E. J. Lyon, J. J. Smee, Coord. Chem. Rev.
2000, 206–207, 533–561; b) D. J. Evans, C. J. Pickett, Chem.
Soc. Rev. 2003, 32, 268–275; c) L.-C. Song, Acc. Chem. Res.
2005, 38, 21–28; d) J.-F. Capon, F. Gloaguen, P. Schollhammer,
J. Talarmin, Coord. Chem. Rev. 2005, 249, 1664–1676.
[2] J. W. Peters, W. N. Lanzilotta, B. J. Lemon, L. C. Seefeldt, Sci-
ence 1998, 282, 1853–1858.
[3] Y. Nicolet, C. Piras, P. Legrand, E. C. Hatchikian, J. C. Fontec-
illa-Camps, Structure 1999, 7, 13–23.
[4] Y. Nicolet, A. L. De Lacey, X. Vernède, V. M. Fernandez, E. C.
Hatchikian, J. C. Fontecilla-Camps, J. Am. Chem. Soc. 2001,
123, 1596–1601.
[5] A. J. Pierik, M. Hulstein, W. R. Hagen, S. P. J. Albracht, Eur.
J. Biochem. 1998, 258, 572–578.
[6] A. L. De Lacey, C. Stadler, C. Cavazza, E. C. Hatchikian,
V. M. Fernandez, J. Am. Chem. Soc. 2000, 122, 11232–11233.
[7] Z. Chen, B. J. Lemon, S. Huang, D. J. Swartz, J. W. Peters,
K. A. Bagley, Biochemistry 2002, 41, 2036–2043.
[8] F. Gloaguen, J. D. Lawrence, M. Schmidt, S. R. Wilson, T. B.
Rauchfuss, J. Am. Chem. Soc. 2001, 123, 12518–12527.
[9] E. J. Lyon, I. P. Georgakaki, J. H. Reibenspies, M. Y. Dar-
ensbourg, J. Am. Chem. Soc. 2001, 123, 3268–3278.
[10] M. Razavet, S. C. Davies, D. L. Hughes, J. E. Barclay, D. J. Ev-
ans, S. A. Fairhurst, X. Liu, C. J. Pickett, Dalton Trans. 2003,
586–595.
[25] D. W. Thomas, A. E. Martell, J. Am. Chem. Soc. 1959, 81,
5111–5119.
[26]
[27]
[28]
B. C. Bookser, T. C. Bruice, J. Am. Chem. Soc. 1991, 113, 4208–
4218.
F. Gloaguen, J. D. Lawrence, T. B. Rauchfuss, J. Am. Chem.
Soc. 2001, 123, 9476–9477.
D. Chong, I. P. Georgakaki, R. Mejia-Rodriguez, J. Sanabria-
Chinchilla, M. P. Soriaga, M. Y. Darensbourg, Dalton Trans.
2003, 4158–4163.
[29] I. Bhugun, D. Lexa, J.-M. Savéant, J. Am. Chem. Soc. 1996,
118, 3982–3983.
[30] R. Mejia-Rodriguez, D. Chong, J. H. Reibenspies, M. P. Sori-
aga, M. Y. Darensbourg, J. Am. Chem. Soc. 2004, 126, 12004–
12014.
[31] D. J. Chadwick, M. V. McKnight, R. Ngochindo, J. Chem. Soc.
Perkin Trans. 1 1982, 1343–1347.
[32] A. J. Carpenter, D. J. Chadwick, J. Chem. Soc. Perkin Trans. 1
1985, 173–181.
[11] L.-C. Song, J. Cheng, J. Yan, H.-T. Wang, X.-F. Liu, Q.-M.
Hu, Organometallics 2006, 25, 1544–1547.
[12] J.-F. Capon, S. E. Hassnaoui, F. Gloaguen, P. Schollhammer, J.
Talarmin, Organometallics 2005, 24, 2020–2022.
[13] F. I. Adam, G. Hogarth, I. Richards, B. E. Sanchez, Dalton
Trans. 2007, 2495–2498.
[14] a) J. D. Lawrence, H. Li, T. B. Rauchfuss, Chem. Commun.
2001, 1482–1483; b) J. L. Stanley, T. B. Rauchfuss, S. R. Wil-
son, Organometallics 2007, 26, 1907–1911.
[33] N. Rabjohn, Organic Syntheses, John Wiley, New York, 1963,
vol. 4, p. 261.
[34] D. S. Breslow, E. Baumgarten, C. Hauser, J. Am. Chem. Soc.
1944, 66, 1286–1288.
[35] a) D. Delorme, C. Berthelette, R. Lavoie, E. Roberts, Tetrahe-
dron: Asymmetry 1998, 9, 3963–3966; b) E. J. Kuhlmann, J. J.
Alexander, Inorg. Chim. Acta 1979, 34, 197–209.
[36] G. M. Sheldrick, SADABS: A Program for Empirical Absorp-
tion Correction of Area Detector Data, University of Göttingen,
Germany, 1996.
[15] L.-C. Song, J.-H. Ge, X.-G. Zhang, Y. Liu, Q.-M. Hu, Eur. J.
Inorg. Chem. 2006, 3204–3210.
[16] W. Gao, J. Ekström, J. Liu, C. Chen, L. Eriksson, L. Weng, B.
Åkermark, L. Sun, Inorg. Chem. 2007, 46, 1981–1991.
[17] L. Schwartz, G. Eilers, L. Eriksson, A. Gogoll, R. Lomoth, S.
Ott, Chem. Commun. 2006, 520–522.
[18] L.-C. Song, Z.-Y. Yang, H.-Z. Bian, Y. Liu, H.-T. Wang, X.-F.
Liu, Q.-M. Hu, Organometallics 2005, 24, 6126–6135.
[37] G. M. Sheldrick, SHELXS97: A Program for Crystal Structure
Solution, University of Göttingen, Germany, 1997.
[38] G. M. Sheldrick, SHELXL97: A Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Received: August 14, 2007
Published Online: October 26, 2007
Eur. J. Inorg. Chem. 2008, 291–297
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
297