Synthesis and Characterization of Diiron Thiadithiolate Complexes Related to the Active Site of [FeFe]-Hydrogenases

Article abstract of DOI:10.1002/ejic.200901023

On the basis of preparation of the known complex [Fe₂(μ SCH₂)2S(CO)₆] (A) by a new method involving condensation of [(μ-LiS)₂Fe₂(CO)₆] with excess S(CH ₂Br)₂, twelve new diiron thiadithiolates as mimics of the [FeFe]-hydrogenase active site have been synthesized by substitution of the CO ligand and coordination at the central S atom of complex A with appropriate reagents. Treatment of A with 1. equiv. of the monodentate ligands PPh ₃ and [(η⁵-C₅.H₅) (η⁵-Ph₂PC₅H₄)Fe] in the presence of Me₃NO and with 1 equiv.tBuNC and cyclohexyl isocyanide gave the single [2Fe3S]-cluster-containing monosubstituted complexes [Fe2(U-SCH2J2S(CO) 5(L₁)] (1, L₁ = PPh₃; 2, L₁ = (η⁵-C₅H₅) (η⁵Ph ₂PC₅H₄)Fe; 3, L₁ = tBuNC; 4, L ₁ = C₆H₁₁NC), whereas the double [2Fe3S]cluster-containing disubstituted complexes [(Fe₂(μ-SCH ₂)₂S(CO)₅}₂(L₂)] [5, L₂ = 4,4'-(Ph₂P)₂(C₆H ₄)₂; 6, L₂ = trans-Ph₂PCH=CHPPh ₂; 7, L₂ = 1,4-(CN)₂C₆H₄; 8, L₂ = (η⁵-Ph₂PC₅H ₄)₂Fe; 9, L₂ = (η⁵-Ph ₂PC₅H₄)₂Ru] were produced by reaction of A with 0.5 equiv. of the corresponding bidentate ligands in the presence of Me₃NO. In addition, the single [2Fe3S]-cluster-containing complexes in which the central S atom is coordinated, [{Fe₂(μ- SCH₂)₂S(CO)₆}[(η⁵-MeC ₅H₄)(CO)₂Fe}(BF₄)] (10), [(Fe ₂(μ-SCH₂)₂S(CO)₆ }{Cr(CO) ₅}] (11), and [(Fe₂(μSCH₂) ₂S(CO)₆}[W(CO)₅}] (12), could be obtained by reaction of complex A with the in situ prepared. [((μ⁵-MeC ₅H₄)(CO)₂Fe)(BF₄)], [Cr(CO) ₅(thf)], and [W(CO)₅;(thf)], respectively. While complex 3 was found to be able to reduce the proton of the weak acid Et₃NHCl to give H₂, the X-ray crystallographic study confirmed that (i) each P atom of the phosphane ligands in 1 and 8 occupies an apical position at the Fe atoms, (ii) the isocyanide ligand in 3 lies in a basal position of the Fe atom, and (iii) the (η⁵MeC₅H₄)(CO) ₂Fe, Cr(CO)₅, and W(CO)₅ units in 10-12 are linked to the central S atom of complex A by an equatorial bond from the two fused sixmembered rings of their [2Fe3S]-cluster cores.

Full text of DOI:10.1002/ejic.200901023

FULL PAPER
DOI: 10.1002/ejic.200901023
Synthesis and Characterization of Diiron Thiadithiolate Complexes Related to
the Active Site of [FeFe]-Hydrogenases
Li-Cheng Song,*[a] Qing-Shan Li,[a] Zhi-Yong Yang,[a] Yu-Juan Hua,[a] Hong-Zhu Bian,[a]
and Qing-Mei Hu[a]
Keywords: Bioinorganic chemistry / Transition metals / Enzyme models / Iron / Hydrogenases
On the basis of preparation of the known complex [Fe2(µ-
SCH2)2S(CO)6] (A) by a new method involving condensation
of [(µ-LiS)2Fe2(CO)6] with excess S(CH2Br)2, twelve new di-
iron thiadithiolates as mimics of the [FeFe]-hydrogenase
active site have been synthesized by substitution of the CO
ligand and coordination at the central S atom of complex A
with appropriate reagents. Treatment of A with 1 equiv. of
the monodentate ligands PPh3 and [(η5-C5H5)(η5-Ph2PC5H4)-
Fe] in the presence of Me3NO and with 1 equiv. tBuNC and
A with 0.5 equiv. of the corresponding bidentate ligands in
the presence of Me3NO. In addition, the single [2Fe3S]-clus-
ter-containing complexes in which the central S atom is coor-
dinated, [{Fe2(µ-SCH2)2S(CO)6}{(η5-MeC5H4)(CO)2Fe}(BF4)]
(10), [{Fe2(µ-SCH2)2S(CO)6}{Cr(CO)5}] (11), and [{Fe2(µ-
SCH2)2S(CO)6}{W(CO)5}] (12), could be obtained by reaction
of complex A with the in situ prepared [{(η5-MeC5H4)(CO)2-
Fe}(BF4)], [Cr(CO)5(thf)], and [W(CO)5(thf)], respectively.
While complex 3 was found to be able to reduce the proton of
cyclohexyl isocyanide gave the single [2Fe3S]-cluster-con- the weak acid Et3NHCl to give H2, the X-ray crystallographic
taining monosubstituted complexes [Fe2(µ-SCH2)2S(CO)5-
(L1)] (1, L1 = PPh3; 2, L1 = (η5-C5H5)(η5-Ph2PC5H4)Fe; 3, L1 =
tBuNC; 4, L1 = C6H11NC), whereas the double [2Fe3S]-
cluster-containing disubstituted complexes [{Fe2(µ-SCH2)2S-
(CO)5}2(L2)] [5, L2 = 4,4Ј-(Ph2P)2(C6H4)2; 6, L2 = trans-Ph2P-
CH=CHPPh2; 7, L2 = 1,4-(CN)2C6H4; 8, L2 = (η5-Ph2PC5H4)2-
Fe; 9, L2 = (η5-Ph2PC5H4)2Ru] were produced by reaction of
study confirmed that (i) each P atom of the phosphane li-
gands in 1 and 8 occupies an apical position at the Fe atoms,
(ii) the isocyanide ligand in 3 lies in a basal position of the
Fe atom, and (iii) the (η5-MeC5H4)(CO)2Fe, Cr(CO)5, and
W(CO)5 units in 10–12 are linked to the central S atom of
complex A by an equatorial bond from the two fused six-
membered rings of their [2Fe3S]-cluster cores.
This is because the central N atom in the ADT cofactor was
recently suggested to play an important role in the hetero-
lytic cleavage of H2 or H2 evolution in natural enzymes.[9]
In addition, the central S atom in the TDT cofactor has a
strong coordination ability with transition metals,[7] which
may provide an easy route to structural modification. On
the basis of our previous study on central heteroatom-con-
taining models, we now report the synthesis and structural
characterization of a series of new single and double diiron
TDT-type models prepared by CO substitution and by coor-
dination at the central S atom of the parent complex [Fe2(µ-
SCH2)2S(CO)6] (A). In addition, a new synthetic method for
the preparation of complex A is also reported.
Introduction
[FeFe]-hydrogenases have attracted great attention in re-
cent years, since they can catalyze proton reduction to hy-
drogen in numerous aerobic and anaerobic microorganisms
at very high rates.[1] Crystallographic[2] and IR spectro-
scopic[3] studies on the two types of [FeFe]-hydrogenases,
CpI (Clostridium pasteurianum) and DdH (Desulfovibrio de-
sulfuricans) have revealed that their active site (the so-called
H-cluster) consists of a butterfly [2Fe2S]-cluster subsite
bearing CO and CN– ligands and a cubic [4Fe4S]-cluster
subsite bearing cysteinyl ligands (Figure 1). To date, a large
number of biomimetic models for the active site of [FeFe]-
hydrogenases have been prepared and structurally charac-
terized, and some have demonstrated the ability to catalyze
proton reduction to hydrogen.[4–8] Among such models, we
are particularly interested in the central heteroatom-contain-
ing models, such as diiron azadithiolate (ADT),[5] oxadithi-
olate (ODT),[6] and thiadithiolate (TDT) type models.[7,8]
[a] Department of Chemistry, State Key Laboratory of Elemento-
Organic Chemistry,
Nankai University,
Figure 1. The simplified structure of the H-cluster in different func-
tional states (L = vacant, H2O, CO, H, or H2; X = CH2, NH, or
O).
Tianjin 300071, China
Fax: +86-22-23504853
E-mail: lcsong@nankai.edu.cn
Eur. J. Inorg. Chem. 2010, 1119–1128
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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L.-C. Song, Q.-S. Li, Z.-Y. Yang, Y.-J. Hua, H.-Z. Bian, Q.-M. Hu
FULL PAPER
Scheme 1.
tached carbonyl groups by substitution of the CO group
by the stronger electron-donating phosphane or isocyanide
ligands.[11] In addition, the IR spectra of 3 and 4 show one
absorption band at ca. 2160 cm–1, which is characteristic of
Results and Discussion
Synthesis and Characterization of the Single [2Fe3S]-
Cluster-Containing TDT-Type Models A and 1–4
1
the terminal isocyanide ligands. The H NMR spectra of 1
There have been two methods previously reported for the
and 2 display two doublets at ca. 2.30 and 2.80 ppm for the
two magnetically different protons in the methylene groups,
while those of 3 and 4 exhibit one singlet at δ = 3.14 ppm
for the two magnetically identical protons in the corre-
sponding methylene groups. Apparently, the latter case is
caused by fast folding of the two fused six-membered rings
in the [2Fe3S]-cluster cores.[12] The 31P NMR signals for the
coordinated P atoms in 1 and 2 appear as a singlet at δ =
64.44 and 55.26 ppm, respectively.
synthesis of complex A, which involve the oxidative ad-
[7]
dition reaction of 1,2,4-trithiolane with Fe3(CO)12 and
[8]
Fe2(CO)9 in thf. Now, we report a new method for the
synthesis of complex A, which involves two elementary
steps in one pot (i) the initial reductive cleavage of the S–S
bond of [(µ-S2)Fe2(CO)6] with Et3BHLi and (ii) the subse-
quent condensation of the resulting intermediate [(µ-LiS)2-
Fe2(CO)6][10] with excess thioether S(CH2Br)2 (Scheme 1).
On studying the synthetic method for parent complex A,
we further found that complex A could react with 1 equiv.
of monodentate phosphane PPh3 or [(η5-C5H5)(η5-
Ph2PC5H4)Fe] in the presence of decarbonylating agent
Me3NO in MeCN to afford the single [2Fe3S]-cluster-con-
taining monosubstituted model complexes [Fe2(µ-SCH2)2S-
(CO)5(PPh3)] (1) or [Fe2(µ-SCH2)2S(CO)5{(η5-C5H5)(η5-
Ph2PC5H4)Fe}] (2) in 89 and 81% yields, respectively. In
addition, it was further found that complex A could also
react with 1 equiv. of monodentate isocyanide tBuNC or
C6H11NC in CH2Cl2 in the absence of Me3NO to give the
corresponding monosubstituted model complexes [Fe2(µ-
SCH2)2S(CO)5(tBuNC)] (3) or [Fe2(µ-SCH2)2S(CO)5-
(C6H11NC)] (4) in 61 and 60% yields, respectively
(Scheme 2).
The molecular structures of 1 and 3 were confirmed by
X-ray crystal diffraction analysis. While molecular struc-
tures of 1 and 3 are presented in Figures 2 and 3, their se-
Figure 2. Molecular structure of 1 with 30% probability level ellip-
soids.
Scheme 2.
Complexes 1–4 are air-stable red solids, which were char-
acterized by elemental analysis and NMR and IR spec-
troscopy. In their IR spectra there are three to four absorp-
tion bands in the range of 2047–1934 cm–1 assigned to the
terminal carbonyls, which are shifted towards lower fre-
quencies relative to those (2075–1990 cm–1) of the parent
complex A.[7] This is obviously due to the increased strength
Figure 3. Molecular structure of 3 with 30% probability level ellip-
of the π back bonding between the iron atoms and the at- soids.
1120
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Eur. J. Inorg. Chem. 2010, 1119–1128

Diiron Thiadithiolate Complexes Related to the [FeFe]-Hydrogenases
lected bond lengths and angles are given in Table 1. As tuted [FeFe]-hydrogenase model complex reported so far,
shown in Figure 2, complex 1 contains one [2Fe3S]-cluster although the crystal structures of some isocyanide-disubsti-
core that carries five CO and one PPh3 ligands. The PPh3 tuted model complexes are known. It is interesting to note
ligand occupies an apical coordination site of the octahe- that the two isocyanide ligands in the crystal structure of
dral geometry of the Fe1 atom (the Fe1–Fe2 bond is re- the model complex [Fe2(µ-SCH2)2CH2(CO)4(tBuNC)2] all
garded as a coordination site), which is in accordance with reside in apical positions,[14] whereas in the crystal structure
the previously reported phosphane-substituted diiron carb- of the model complex [Fe2(µ-SCH2)2S(CO)4(tBuNC)2], one
onyl complexes.[13] Interestingly, although complex 3 has isocyanide group resides in an apical position and the other
the same [2Fe3S]-cluster core with five CO ligands, the in a basal position.[7]
tBuNC ligand, in contrast to PPh3 of 1, lies in the basal
position of one Fe atom. To the best of our knowledge, this
is the first crystal structure of the isocyanide-monosubsti-
Synthesis and Characterization of the Double [2Fe3S]-
Cluster-Containing TDT-Type Models 5–9
Table 1. Selected bond lengths [Å] and angles [°] for 1 and 3.
Interestingly, it was found that the double [2Fe3S]-clus-
1
3
ter-containing disubstituted model compounds [{Fe2(µ-
SCH2)2S(CO)5}2(L2)] [5, L2 = 4,4Ј-(Ph2P)2(C6H4)2; 6, trans-
Ph2PCH=CHPPh2; 7, 1,4-(CN)2C6H4; 8, (η5-Ph2PC5H4)2-
Fe (dppf); 9, (η5-Ph2PC5H4)2Ru (dppr)] {1,1Ј-bis(diphenyl-
phosphanyl)ferrocene (dppf) and 1,1Ј-bis(diphenylphos-
phanyl)ruthenocene (dppr)} could similarly be prepared in
42–73% yields by CO substitution reactions of parent com-
plex A with 0.5 equiv. of the corresponding bidentate li-
gands in the presence of Me3NO in MeCN (Scheme 3).
Compounds 5–9 are air-stable dark-red solids, which
were characterized by elemental analysis and NMR and IR
spectroscopy, and for 8 by X-ray crystallography. For exam-
ple, the IR spectra of 5–9 display three absorption bands
in the range 2047–1932 cm–1, which can be assigned to the
terminal carbonyl groups, whereas complex 7 exhibits an
additional absorption band at 2118 cm–1 for the bridged di-
Fe1–P1
Fe1–S1
Fe2–S1
S1–C6
S3–C7
Fe1–S2
Fe1–Fe2
Fe2–S2
2.2527(14)
2.2934(12)
2.2691(12)
1.834(4)
Fe1–S1
Fe1–S2
Fe1–Fe2
Fe2–S2
Fe2–S1
S1–C12
S2–C11
S3–C11
2.2594(6)
2.2681(6)
2.5313(5)
2.2405(5)
2.2636(5)
1.8303(17)
1.8316(17)
1.7846(17)
1.7847(19)
1.157(2)
86.182(18)
56.047(14)
55.330(12)
86.74(2)
1.770(4)
2.2620(12)
2.5108(11)
2.2747(13)
1.842(4)
1.783(4)
155.31(4)
56.15(3)
57.08(3)
110.04(13)
66.77(4)
56.64(3)
85.49(5)
S2–C7
S3–C6
S3–C12
N1–C6
P1–Fe1–Fe2
S1–Fe1–Fe2
S1–Fe2–Fe1
C6–S1–Fe2
Fe2–S1–Fe1
S2–Fe1–Fe2
S1–Fe2–S2
S2–Fe2–Fe1
C6–S1–Fe1
Fe1–S2–Fe2
S1–Fe1–S2
S1–Fe1–Fe2
S2–Fe1–Fe2
S2–Fe2–S1
S2–Fe2–Fe1
S1–Fe2–Fe1
Fe1–S1–Fe2
Fe2–S2–Fe1
C11–S3–C12
C6–N1–C7
56.365(17)
55.890(15)
68.06(2)
68.305(17)
99.33(8)
56.16(4)
120.47(14)
67.20(4)
1
isonitrile. In addition, the H NMR spectra of 5–9 show
the corresponding proton signals for the organic groups.
173.07(17)
Scheme 3.
Eur. J. Inorg. Chem. 2010, 1119–1128
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1121

L.-C. Song, Q.-S. Li, Z.-Y. Yang, Y.-J. Hua, H.-Z. Bian, Q.-M. Hu
FULL PAPER
The 31P NMR spectra of 5, 6, 8 and 9 each exhibit one S-coordinated TDT-type model [{Fe2(µ-SCH2)2S(CO)6}-
singlet in the range 54–65 ppm for the two identical P atoms {Cp(CO)2Fe}(BF4)][7] and the other is the oxidation reac-
in each of the diphosphane ligands. The molecular structure tion with dimethyldioxirane to afford, for example, the or-
of 8 determined by X-ray crystallography is shown in Fig- ganometallic sulfoxide and sulfone products [Fe2(µ-SCH2)2-
ure 4, while Table 2 lists its selected bond lengths and S(O)(CO)6] and [Fe2(µ-SCH2)2S(O2)(CO)6].[15] To demon-
angles. As can be seen in Figure 4, complex 8 indeed com- strate the coordination ability of the central S atom of com-
prises two [2Fe3S]-cluster cores, which are joined together plex A with different organometallic substrates, we carried
through the apically positioned P1 and P1A atoms of the out reactions of complex A with [{(η5-MeC5H4)(CO)2Fe}-
bridging dppf ligand. This molecule is centrosymmetric. (BF4)] (prepared in situ from [(η5-MeC5H4)(CO)2FeI] and
Both the S3 and S3A atoms lie opposite the diphosphane AgBF4)[16] in CH2Cl2 at room temperature and with M(CO)5-
ligand, probably in order to avoid the strong steric repul- (thf) (M = Cr, W) (prepared in situ by photolysis of M-
sion between the two sulfur atoms and the bulky dppf li- (CO)6 with thf)[17] in thf at room temperature. As a result,
gand. Actually, this structure is isostructural with that of the corresponding S-coordinated TDT-type model com-
the ODT-type model [{Fe2(µ-SCH2)2O(CO)5}2(dppf)].[6]
plexes
[{Fe2(µ-SCH2)2S(CO)6}{(η5-MeC5H4)(CO)2Fe}-
(BF4)] (10), [{Fe2(µ-SCH2)2S(CO)6}{Cr(CO)5}] (11), and
[{Fe2(µ-SCH2)2S(CO)6}{W(CO)5}] (12) were obtained in
76, 83, and 82% yields, respectively (Scheme 4).
Complexes 10–12 are air-stable red solids, which were
fully characterized by elemental analysis, NMR and IR
spectroscopy, and X-ray crystallography. The IR spectra of
10–12 show four to eight strong absorption bands in the
range 2086–1897 cm–1 assigned to the terminal carbonyl
groups. The highest absorption bands assigned to the two
Fe(CO)3 units lie at frequencies higher (2086–2083 cm–1)
than that (2075 cm–1) of parent complex A.[7] This is appar-
ently due to the decreased π back bonding after the elec-
tron-withdrawing groups of [{(η5-MeC5H4)(CO)2Fe}]+ and
M(CO)5 coordinate to the central S atom.[11] Similarly to
Figure 4. Molecular structure of 8 with 30% probability level ellip-
soids.
Table 2. Selected bond lengths [Å] and angles [°] for 8.
1
the spectra of 1–4, the H NMR spectrum of 10 shows two
Fe1–S2
Fe1–S1
Fe1–Fe2
Fe2–P1
2.2581(8)
2.2726(9)
2.5255(6)
2.2505(8)
2.2573(8)
85.52(3)
55.98(2)
56.26(2)
108.98(3)
152.91(3)
Fe2–S1
S1–C6
S2–C7
S3–C7
2.2732(9)
1.825(4)
1.824(4)
1.770(4)
1.791(4)
56.01(2)
56.24(2)
67.50(3)
68.02(3)
99.71(17)
doublets at δ = 3.49 and 4.03 ppm for the two magnetically
different protons in the CH2 groups, whereas those of 11
and 12 display one singlet at δ = 3.17 and 3.34 ppm for the
two magnetically identical protons in their CH2 groups. In
addition, the 19F NMR spectrum of 10 shows one singlet at
Fe2–S2
S3–C6
S2–Fe1–S1
S2–Fe1–Fe2
S1–Fe1–Fe2
P1–Fe2–S1
P1–Fe2–Fe1
S2–Fe2–Fe1
S1–Fe2–Fe1
Fe1–S1–Fe2
Fe2–S2–Fe1
C7–S3–C6
–
–151.67 ppm, which can be assigned to the BF4 anion.[18]
The molecular structures of 10–12 are depicted in Fig-
ures 5, 6, and 7, whereas their selected bond lengths and
angles are presented in Table 3. As can be seen intuitively
from Figures 5, 6, and 7, the three complexes are indeed the
expected derivatives generated by coordination of the cen-
tral S atom of the parent complex A with transition-metal
atoms Fe1, Cr1, and W1 through a common equatorial
bond of the two fused six-membered rings (Fe2–S2–C9–S1–
Synthesis and Characterization of the Central-S-
Coordinated TDT-Type Models 10–12
To date, only two types of reactions are known that in- C10–S3/Fe3–S2–C9–S1–C10–S3 for 10, and Fe1–S1–C12–
volve the central S atom of complex A. One is the coordina- S3–C13–S2/Fe2–S1–C12–S3–C13–S2 for 11 and 12). Such
tion reaction with Cp(CO)2Fe(BF4) to give the first central- an equatorial type of conformational arrangement in 10–12
Scheme 4.
1122
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Eur. J. Inorg. Chem. 2010, 1119–1128

Diiron Thiadithiolate Complexes Related to the [FeFe]-Hydrogenases
apparently occurs in order to avoid the strong steric repul- noted that in the solid-state structure of 10 there are two
sion between the apically located carbonyl ligand in moiety types of weak interactions between its complex cation and
–
A and the bulky axially attached [(η5-MeC5H4)(CO)2Fe] or the anion BF4 : (i) the F1 atom is involved in a weak hydro-
M(CO)5 (M = Cr, W) moiety. In addition, all the iron atoms gen-bond interaction in C9–H9A···F1,[19] since the
in 10–12, as well as both Cr1 and W1 atoms in 11 and 12, F1···H9A distance (2.526 Å) is smaller than the sum of the
have a distorted octahedral geometry. Finally, it should be van der Waal’s radii of the hydrogen atom (1.20 Å)[20] and
the fluorine atom (1.47 Å),[21] and (ii) a weak interaction
occurs between the negatively charged F1 atom and the
positively charged S1 atom as a result of delocalization of
the positive charge of the cationic Fe1 atom. This is consis-
tent with the fact that the F1···S1 distance (3.165 Å) is
smaller than the sum of the van der Waal’s radii of the
fluorine atom (1.47 Å) and the sulfur atom (1.80 Å).[21]
Table 3. Selected bond lengths [Å] and angles [°] for 10–12.
10
Fe1–S1
Fe2–S3
Fe2–S2
Fe2–Fe3
2.2448(13)
2.2382(14)
2.2479(12)
2.5094(11)
2.2523(13)
86.60(4)
56.42(3)
56.19(4)
86.05(5)
56.03(3)
Fe3–S3
S1–C9
S1–C10
S2–C9
2.2568(13)
1.789(4)
1.797(4)
1.809(4)
1.806(4)
55.71(4)
98.87(18)
67.78(4)
67.87(4)
115.71(19)
Fe3–S2
S3–C10
S3–Fe2–S2
S3–Fe2–Fe3
S2–Fe2–Fe3
S2–Fe3–S3
S2–Fe3–Fe2
S3–Fe3–Fe2
C9–S1–C10
Fe2–S2–Fe3
Fe2–S3–Fe3
S1–C9–S2
Figure 5. Molecular structure of 10 with 30% probability level el-
lipsoids.
11
Fe1–S2
Fe1–S1
Fe1–Fe2
Fe2–S2
2.2496(12)
2.2568(13)
2.5116(10)
2.2477(12)
2.2558(12)
86.33(4)
56.01(3)
56.16(3)
86.40(4)
56.08(3)
Cr1–S3
S1–C12
S2–C13
S3–C12
2.4368(12)
1.816(4)
1.818(4)
1.794(4)
1.795(4)
56.20(4)
67.64(4)
67.90(4)
99.19(18)
89.54(13)
Fe2–S1
S3–C13
S2–Fe1–S1
S2–Fe1–Fe2
S1–Fe1–Fe2
S2–Fe2–S1
S2–Fe2–Fe1
S1–Fe2–Fe1
Fe2–S1–Fe1
Fe2–S2–Fe1
C12–S3–C13
C7–Cr1–S3
12
Fe1–S1
Fe1–S2
Fe1–Fe2
Fe2–S2
2.2569(18)
2.2585(19)
2.5139(14)
2.253(2)
2.2569(18)
86.38(6)
56.15(5)
56.04(5)
86.50(7)
56.24(5)
W1–S3
S1–C12
S2–C13
S3–C12
2.5656(15)
1.826(6)
1.818(5)
1.795(6)
1.795(6)
56.16(5)
67.69(5)
67.72(6)
99.3(3)
Figure 6. Molecular structure of 11 with 30% probability level el-
lipsoids.
Fe2–S1
S3–C13
S1–Fe1–S2
S1–Fe1–Fe2
S2–Fe1–Fe2
S2–Fe2–S1
S2–Fe2–Fe1
S1–Fe2–Fe1
Fe2–S1–Fe1
Fe2–S2–Fe1
C12–S3–C13
C7–W1–S3
89.28(18)
Electrochemical H2 Evolution Catalyzed by Model Complex
3
On the basis of our previous study on the electrochemical
and electrocatalytic properties of parent complex A,[7] we
continue to investigate these properties of model complex 3
under the same conditions as those reported for its parent
complex A. As can be seen from the cyclic voltammogram
(Figure 8) and differential pulse voltammogram (inset in
Figure 8), complex 3 displays a quasi-reversible reduction
at Epc = –1.76 V, an irreversible reduction at Epc = –1.98 V,
Figure 7. Molecular structure of 12 with 30% probability level el-
lipsoids.
Eur. J. Inorg. Chem. 2010, 1119–1128
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1123

L.-C. Song, Q.-S. Li, Z.-Y. Yang, Y.-J. Hua, H.-Z. Bian, Q.-M. Hu
FULL PAPER
and an irreversible oxidation at Epa = +0.49 V. Similarly to
the redox processes of parent complex A, the first reduction
process could be assigned to the one-electron reduction of
[FeIFeI] to [FeIFe0], the second reduction process to the re-
duction of [FeIFe0] to [Fe0Fe0], and the oxidation process
to the oxidation of [FeIFeI] to [FeIFeII]. Actually, the cyclic
voltammetric behavior of model complex 3 is very similar
to that of its parent complex A, with the exception that the
reduction and oxidation potentials of 3 are more negative
than those of the corresponding processes of its parent
complex A (–1.51, –1.94 and +0.79 V), because of the
greater electron-donating ability of the isocyanide ligand
tBuNC than the carbonyl ligand.
Figure 9. Cyclic voltammogram of 3 (1.0 m) with Et3NHCl (0–
10 mg) in 0.1  nBu4NPF6/MeCN at a scan rate of 100 mVs–1.
and 12 with complex A were unsuccessful because of their
serious decomposition under the electrochemical conditions
used.
Conclusions
Substitution of the CO group and coordination at the
central S atom of parent complex A have been systemati-
cally studied, which allows us to obtain not only the single
[2Fe3S]-cluster-containing monodentate-ligand-substituted
TDT-type models 1–4, but also the double [2Fe3S]-cluster-
containing bidentate-ligand-bridged TDT-type models 5–9,
and the central-S-coordinated TDT-type models 10–12. The
spectroscopic and X-ray crystallographic studies on these
new complexes have provided detailed structural and con-
formational information, while a comparative study on the
electrochemical and electrocatalytic properties of model 3
and the parent complex A is preliminarily carried out. Fur-
ther studies on the structural modification of parent com-
plex A, as well as on the reduction of the proton to hydro-
gen catalyzed by such structurally modified TDT-type mod-
els are in progress in this laboratory.
Figure 8. Cyclic voltammogram of 3 (1.0 m) in 0.1  nBu4NPF6/
MeCN at a scan rate of 100 mVs–1; inset: differential pulse voltam-
mogram of 3.
A further cyclic voltammetric study indicates that model
3 has the ability to reduce a proton of a proton donor such
as Et3NHCl (pKa = 18.7 in MeCN) to give hydrogen. As
shown in Figure 9, upon addition of the first 2 mg of
Et3NHCl to the solution of 3, the initial first reduction
peak at –1.76 V slightly increases, but does not continue
to grow with sequential addition of Et3NHCl. However, in
contrast to this, upon addition of the first 2 mg of
Et3NHCl, the initial second reduction peak at –1.98 V re-
markably increases and continues to increase with increas-
ing concentration of the acid. Such observations are typical
of an electrocatalytic proton-reduction process.[6,22–24]
The electrocatalytic activity of 3 was determined by bulk
Experimental Section
General Comments: All manipulations were performed by using
standard Schlenk and vacuum-line techniques under N2 atmo-
sphere. Dichloromethane and acetonitrile were distilled from P2O5
under N2. Hexane and thf were purified by distillation under N2
electrolysis of a MeCN solution of 3 (0.5 m) with excess from Na/benzophenone ketyl. Et3BHLi (1  in thf), tert-butyl iso-
cyanide, cyclohexyl isocyanide, Cr(CO)6, W(CO)6, AgBF4, PPh3,
and trans-Ph2PCH=CHPPh2 were available commercially and used
without further purification. [(µ-S)2Fe2(CO)6],[10] S(CH2Br)2,[25]
1,1Ј-bis(diphenylphosphanyl)ferrocene (dppf),[26] 1,1Ј-bis(diphenyl-
phosphanyl)ruthenocene (dppr),[27] 1,4-(CN)2C6H4,[28] [(η5-C5H5)-
(η5-Ph2PC5H4)Fe],[29] 4,4Ј-(Ph2P)2(C6H4)2,[30] and [(η5-MeC5H4)-
Fe(CO)2I][31] were prepared according to literature procedures. Pre-
parative TLC was carried out on glass plates (26ϫ20ϫ0.25 cm)
coated with silica gel H (10–40 µm). IR spectra were recorded on
a Bio-Rad FTS 135 infrared spectrophotometer. 1H, 31P, and 19F
Et3NHCl (25 m) under the same conditions as those re-
ported for parent complex A.[7] The total charge passed
through the cell is 16.5 Fmol–1 of 3 during the course of
0.5 h, which corresponds to 8.2 turnovers. Gas chromato-
graphic analysis shows that the hydrogen yield is about
95%. It follows that the electrocatalytic activity of parent
complex A[7] is not improved by substitution of the CO
group with tBuNC (to give 3). It is worth pointing out that
our attempts to compare the electrochemical and electrocat-
alytic properties of the central-S-coordinated complexes 11 NMR spectra were recorded on a Bruker AC-P 200, a Bruker Av-
1124 Eur. J. Inorg. Chem. 2010, 1119–1128
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Diiron Thiadithiolate Complexes Related to the [FeFe]-Hydrogenases
ance 300, and a Varian Mercury Plus 400 NMR spectrometer.
Chemical shifts are given in ppm and referenced to tms (1H), 85%
H3PO4 (31P), and CFCl3 (19F), respectively. Elemental analyses
were performed on an Elementar Vario EL analyzer. Melting
points were determined on a Yanaco MP-500 apparatus.
0.1 mmol) in MeCN (10 mL) was added a solution of
Me3NO·2H2O (0.022 g, 0.2 mmol) in MeCN (5 mL), and the mix-
ture was then stirred at room temperature for 0.5 h. After the sol-
vent was removed in vacuo, the residue was subjected to TLC sepa-
ration by using CH2Cl2/petroleum ether (v/v = 1:4) as eluent. From
the main red band, 5 (0.093 g, 73%) was obtained as a dark red
[Fe2(µ-SCH2)2S(CO)6] (A): A solution of [(µ-S2)Fe2(CO)6] (0.344 g,
1.0 mmol) in thf (15 mL) was cooled to –78 °C, and LiEt3BH
(2 mL, 2.0 mmol) was then slowly added. After stirring the re-
sulting green solution for 10 min, S(CH2Br)2 (0.2 mL, 1.5 mmol)
was added. The new mixture was warmed to room temperature and
stirred at this temperature for 2 h to give a red solution. The solvent
was removed in vacuo, and the residue was subjected to TLC sepa-
ration by using CH2Cl2/petroleum ether (v/v = 1:10) as eluent.
From the main red band, A was obtained as a red solid (0.098 g,
24%), which was identified by comparison of its melting point, and
1
solid. M.p. 203 °C (dec.). H NMR (300 MHz, CDCl3): δ = 7.76,
7.44 (2s, 28 H, 4 C6H5 and 2 C6H4), 2.86, 2.39 (2d, J = 10.6 Hz, 8
H, 4CH2) ppm. 31P NMR (121 MHz, CDCl3): δ = 64.07 (s) ppm.
IR (KBr disk): ν = 2047 (vs), 1984 (vs), 1935 (CϵO) (s) cm–1.
˜
C50H36Fe4O10P2S6 (1274.53): calcd. C 47.12, H 2.85; found C
46.99, H 3.01.
[{Fe2(µ-SCH2)2S(CO)5}2(trans-Ph2PCH=CHPPh2)] (6): The same
procedure as that of 5 was followed, with the exception that 4,4Ј-
(Ph2P)2(C6H4)2 was replaced by trans-Ph2PCH=CHPPh2 (0.040 g,
0.1 mmol). From the main red band, 6 (0.068 g, 59%) was obtained
as a dark red solid. M.p. 195 °C (dec.). 1H NMR (300 MHz,
CDCl3): δ = 7.73, 7.46 (2s, 20 H, 4 C6H5), 7.12, 7.06 (2d, J =
11.0 Hz, 2 H, trans-CH=CH), 2.80, 2.28 (2d, J = 11.8 Hz, 8 H, 4
CH2) ppm. 31P NMR (121 MHz, CDCl3): δ = 59.27 (s) ppm. IR
1
IR and H NMR spectra with those of an authentic sample.[7]
[Fe2(µ-SCH2)2S(CO)5(PPh3)] (1): To a solution of A (0.081 g,
0.2 mmol) and Ph3P (0.053 g, 0.2 mmol) in MeCN (10 mL) was
added a solution of Me3NO·2H2O (0.022 g, 0.2 mmol) in MeCN
(5 mL), and the mixture was then stirred at room temperature for
0.5 h. The solvent was removed in vacuo, and the residue was sub-
jected to TLC separation by using CH2Cl2/petroleum ether (v/v =
1:5) as eluent. From the main red band, 1 was obtained as a dark
red solid (0.113 g, 89%). M.p. 174–176 °C. 1H NMR (200 MHz,
CDCl3): δ = 7.76, 7.42 (2s, 15 H, 3 C6H5), 2.84, 2.33 (2d, J =
13.6 Hz, 4 H, 2 CH2) ppm. 31P NMR (121 MHz, CDCl3): δ = 64.44
(KBr disk): ν = 2047 (vs), 1985 (vs), 1934 (CϵO) (s), 1651 (C=C)
˜
(w) cm–1. C40H30Fe4O10P2S6 (1148.38): calcd. C 41.84, H 2.63;
found C 42.07, H 2.62.
[{Fe2(µ-SCH2)2S(CO)5}2{1,4-(CN)2C6H4}] (7): To a solution of A
(0.081g, 0.2 mmol) in MeCN (10 mL) was added Me3NO·2H2O
(0.022 g, 0.2 mmol). After the mixture was stirred at room tempera-
ture for 20 min, 1,4-(CN)2C6H4 (0.013 g, 0.1 mmol) was added. The
new mixture was stirred for 4 h. The solvent was removed at re-
duced pressure, and the residue was subjected to TLC separation
by using CH2Cl2/petroleum ether (v/v = 1:4) as eluent. From the
main red band, 7 (0.040 g, 45%) was obtained as a dark red solid.
(s) ppm. IR (KBr disk): ν = 2045 (vs), 1976 (vs), 1934 (CϵO) (s)
˜
cm–1. C25H19Fe2O5PS3 (638.27): calcd. C 47.04, H 3.00; found C
46.94, H 3.02.
[Fe2(µ-SCH2)2S(CO)5{(η5-C5H5)(η5-Ph2PC5H4)Fe}] (2): The same
procedure as that of 1 was followed, except that PPh3 was replaced
by [(η5-C5H5)(η5-Ph2PC5H4)Fe] (0.074 g, 0.2 mmol). From the
main red band, 2 (0.121 g, 81%) was obtained as a dark red solid.
1
M.p. 138 °C (dec.). H NMR (200 MHz, CDCl3): δ = 7.28 (s, 4 H,
C H ), 3.19 (s, 8 H, 4 CH ) ppm. IR (KBr disk): ν = 2118 (NϵC)
˜
6
4
2
(vs), 2043 (vs), 2005 (vs), 1978 (CϵO) (vs) cm–1. C22H12Fe4N2O10S6
(880.11): calcd. C 30.02, H 1.37, N 3.18; found C 30.08, H 1.41, N
3.17.
1
M.p. 149–150 °C. H NMR (300 MHz, CDCl3): δ = 7.68, 7.42 (2s,
10 H, 2 C6H5), 4.52 (s, 4 H, C5H4), 3.92 (s, 5 H, C5H5), 2.78, 2.31
(2d, J = 12.5 Hz, 4 H, 2 CH2) ppm. 31P NMR (121 MHz, CDCl3):
δ = 55.26 (s) ppm. IR (KBr disk): ν = 2047 (vs), 1981 (vs), 1934
˜
[{Fe2(µ-SCH2)2S(CO)5}2(dppf)] (8): The same procedure as that of
7 was followed, with the exception that 1,4-(CN)2C6H4 was re-
placed by dppf (0.056 g, 0.1 mmol). From the main red band, 8
(0.055 g, 42%) was obtained as a dark red solid. M.p. 137 °C (dec.).
1H NMR (300 MHz, CDCl3): δ = 7.57, 7.40 (2s, 20 H, 4 C6H5),
4.26 (s, 8 H, 2 C5H4), 2.78, 2.31 (2d, J = 11.7 Hz, 8 H, 4 CH2)
ppm. 31P NMR (121 MHz, CDCl3): δ = 55.79 (s) ppm. IR (KBr
(CϵO) (s) cm–1. C29H23Fe3O5PS3 (746.19): calcd. C 46.68, H 3.11;
found C 46.45, H 3.26.
[Fe2(µ-SCH2)2S(CO)5(tBuNC)] (3): To a solution of A (0.202 g,
0.5 mmol) in CH2Cl2 (20 mL) was added tBuNC (0.056 mL,
0.5 mmol), and the mixture was then stirred at room temperature
for 20 h. After removal of the solvent at reduced pressure, the resi-
due was subjected to TLC separation by using CH2Cl2/petroleum
ether (v/v = 1:3) as eluent. From the main red band, 3 (0.141 g,
61%) was obtained as a red solid. M.p. 121–122 °C. 1H NMR
(400 MHz, CDCl3): δ = 3.14 (s, 4 H, 2 CH2), 1.43 (s, 9 H, C-
disk):
ν =
˜
2047 (vs), 1982 (vs), 1932 (CϵO) (s) cm–1.
C48H36Fe5O10P2S6 (1306.36): calcd. C 44.13, H 2.78; found C
44.23, H 2.78.
[{Fe2(µ-SCH2)2S(CO)5}2(dppr)] (9): The same procedure as that of
7 was followed, with the exception that 1,4-(CN)2C6H4 was re-
placed by dppr (0.060 g, 0.1 mmol). From the main red band, 9
(0.093 g, 69%) was obtained as a dark red solid. M.p. 174 °C (dec.).
1H NMR (200 MHz, CDCl3): δ = 7.63–7.38 (m, 20 H, 4 C6H5),
4.61, 4.49 (2s, 8 H, 2 C5H4), 2.82, 2.39 (2d, J = 13.4 Hz, 8 H, 4
CH2) ppm. 31P NMR (81 MHz, CDCl3): δ = 54.61 (s) ppm. IR
(CH ) ) ppm. IR (KBr disk): ν = 2163 (vs) NϵC, 2038 (vs), 2006
˜
3 3
(vs), 1992 (vs), 1969 (CϵO) (vs) cm–1. C12H13Fe2NO5S3 (459.12):
calcd. C 31.39, H 2.85, N 3.05; found C 31.47, H 2.85, N 3.10.
[Fe2(µ-SCH2)2S(CO)5(C6H11NC)] (4): To a solution of A (0.081 g,
0.2 mmol) in CH2Cl2 (10 mL) was added C6H11NC (0.025 mL,
0.2 mmol), and the mixture was then stirred at room temperature
for 20 h. The same workup as that of 3 gave compound 4 (0.058 g,
(KBr disk): ν = 2047 (vs), 1986 (vs), 1934 (CϵO) (s) cm–1.
˜
1
C48H36Fe4O10P2RuS6 (1351.58): calcd. C 42.66, H 2.68; found C
60%) as a red solid. M.p. 74–75 °C. H NMR (400 MHz, CDCl3):
42.38, H 2.48.
δ = 3.79 (s, 1 H, CH of cyclohexyl), 3.14 (s, 4 H, 2 CH2S), 1.88,
1.70, 1.39 (3s, 10 H, 5 CH2 of cyclohexyl) ppm. IR (KBr disk):
˜
C14H15Fe2NO5S3 (485.16): calcd. C 34.66, H 3.12, N 2.89; found
C 34.89, H 3.24, N 2.85.
[{Fe2(µ-SCH2)2S(CO)6}{(η5-MeC5H4)(CO)2Fe}(BF4)] (10): To
a
ν = 2161 (NϵC) (s), 2044 (s), 2000 (vs), 1969 (CϵO) (vs) cm–1.
suspension of AgBF4 (0.049 g, 0.25 mmol) in CH2Cl2 (15 mL) was
added [(η5-MeC5H4)(CO)2FeI] (0.079 g, 0.25 mmol). The mixture
was stirred in the dark for 2 h. During this period, the amount
of white AgBF4 diminished, and a red solution containing [{(η5-
MeC5H4)(CO)2Fe}(BF4)] was formed. To this solution was added
[{Fe2(µ-SCH2)2S(CO)5}2{4,4Ј-(Ph2P)2(C6H4)2}] (5): To a solution
of
A (0.081g, 0.2 mmol) and 4,4Ј-(Ph2P)2(C6H4)2 (0.053 g,
Eur. J. Inorg. Chem. 2010, 1119–1128
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1125

L.-C. Song, Q.-S. Li, Z.-Y. Yang, Y.-J. Hua, H.-Z. Bian, Q.-M. Hu
FULL PAPER
A (0.121 g, 0.30 mmol), and the mixture was then stirred for an
additional 2 h. The resulting mixture was filtered to remove insolu-
ble materials, and the filtrate was evaporated to dryness in vacuo.
The crude product was washed thoroughly with hexane and dried
in vacuo to give 10 (0.130 g, 76%) as a red solid. M.p. 186 °C (dec.).
1H NMR [400 MHz, (CD3)2CO]: δ = 5.55–5.53 (m, 4 H, C5H4),
Electrochemistry: A solution of 0.1  nBu4NPF6 in MeCN (Fisher
Chemicals, HPLC grade) was used as the electrolyte in all cyclic
voltammetric experiments. The electrolyte solution was degassed
by bubbling dry N2 through for 10 min before measurement. Elec-
trochemical measurements were made by using a BAS Epsilon po-
tentiostat. All voltammograms were obtained in a three-electrode
4.03, 3.49 (2d, J = 11.2 Hz, 2 H, 2 CH2), 2.07 (s, 3 H, CH3) ppm. cell with a 3-mm diameter glassy carbon working, a platinum
19F NMR [376 MHz, (CD3)2CO]: δ = –151.67 (s, BF4) ppm. IR counter, and an Ag/Ag+ (0.01  AgNO3/0.1  nBu4NPF6 in
(KBr disk): ν = 2086 (s), 2052 (vs), 2039 (vs), 2012 (CϵO) (vs), MeCN) reference electrode under N2 atmosphere. The working
˜
1123 (m), 1083 (s), 1035 (B–F) (m) cm–1. C16H11BF4Fe3O8S3 electrode was polished with 1 µm alumina paste and sonicated in
(681.79): calcd. C 28.19, H 1.63; found C 28.07, H 1.60.
water for 10 min prior to use. All potentials are quoted against
the ferrocene/ferrocenium (Fc/Fc+) potential. Bulk electrolyses for
electrocatalytic reactions were carried out under N2 or CO atmo-
sphere by using a BAS Epsilon potentiostat. Electrocatalytic ex-
periments were run on a glassy carbon rod (2.9 cm2) in a two-com-
partment, gastight, H-type electrolysis cell containing MeCN
(25 mL). The electrolyses of solutions were carried out under
hydrodynamic conditions, by vigorously stirring the solution to
mitigate mass transport complications. Gas chromatography was
performed with a Shimadzu gas chromatograph GC-9A under iso-
thermal conditions with nitrogen as a carrier gas and a thermal
conductivity detector.
[{Fe2(µ-SCH2)2S(CO)6}{Cr(CO)5}] (11): stirred solution of
A
[Cr(CO)6] (0.066 g, 0.30 mmol) in thf (25 mL) was irradiated for
1.5 h at room temperature by using a water-cooled UV 450-W mer-
cury vapor lamp to give an orange solution containing ca.
0.30 mmol [Cr(CO)5(thf)]. To this solution was added A (0.061 g,
0.15 mmol), and the mixture was then stirred at room temperature
for 2 h. The solvent was removed in vacuo, and the residue was
subjected to TLC separation by using CH2Cl2/petroleum ether
(v/v = 1:15) as eluent. From the main red band, 11 (0.074 g, 83%)
was obtained as a red solid. M.p. 128 °C (dec.). 1H NMR
(200 MHz, CDCl3): δ = 3.17 (s, 4 H, 2 CH2) ppm. IR (KBr disk):
ν = 2083 (s), 2069 (vs), 2045 (vs), 2006 (vs), 1959 (vs), 1937 (vs),
˜
X-ray Structure Determinations of 1, 3, 8, and 10–12: Single crystals
of 1, 3, 8, and 10–12 suitable for X-ray diffraction analyses were
grown by slow evaporation of CH2Cl2/n-hexane solutions of 1, 3,
and 8 and CH2Cl2/petroleum ether solutions of 11 and 12 at 4 °C,
while a single crystal of 10 was obtained by slow diffusion of anhy-
drous diethyl ether into a saturated solution of 10 in acetone at
–20 °C. The single crystals of 1, 8, and 10–12 were mounted on a
Bruker SMART 1000 automated diffractometer. Data were col-
lected at room temperature by using a graphite monochromator
with Mo-Kα radiation (λ = 0.71073 Å) in the ω–φ scanning mode.
Absorption correction was performed by the SADABS program.[32]
1926 (vs), 1904 (CϵO) (vs) cm–1. C13H4CrFe2O11S3 (596.05): calcd.
C 26.20, H 0.68; found C 26.28, H 0.78.
[{Fe2(µ-SCH2)2S(CO)6}{W(CO)5}] (12): To an orange solution of
[W(CO)5(thf)] (ca. 0.4 mmol), which was prepared in situ by pho-
tolysis of [W(CO)6] (0.141 g, 0.4 mmol) in thf (40 mL) under the
same conditions as described above for 11, was added A (0.081 g,
0.2 mmol). After the mixture was stirred at room temperature for
2 h, the same workup as that of 11 afforded compound 12 (0.120 g,
82%) as a red solid. M.p. 136 °C (dec.). 1H NMR (200 MHz,
CDCl ): δ = 3.34 (s, 4 H, 2 CH ) ppm. IR (KBr disk): ν = 2084
˜
3
2
(s), 2074 (vs), 2045 (vs), 2008 (vs), 1959 (vs), 1937 (vs), 1918 (vs), The single crystal of 3 was mounted on a Rigaku MM-007 (rotat-
1897 (CϵO) (vs) cm–1. C13H4Fe2O11S3W (727.89): calcd. C 21.45,
H 0.55; found C 21.38, H 0.52.
ing anode) diffractometer equipped with Saturn 70CCD. Data col-
lection, reduction, and absorption correction were performed by
Table 4. Crystal data and structure refinement details for 1, 3 and 8.
1
3
8
Formula
C25H19Fe2O5PS3
638.25
293(2)
C12H13Fe2NO5S3
459.11
113(2)
C48H36Fe5O10P2S6·2CH2Cl2
1476.17
293(2)
Mr [gmol–1]
T [K]
Crystal system
Space group
monoclinic
P21/n
monoclinic
C2/c
triclinic
P1
¯
a [Å]
b [Å]
c [Å]
α [°]
11.459(5)
15.054(6)
16.358(6)
90
108.615(7)
90
2674.3(18)
4
1.585
21.830(4)
9.5532(17)
18.433(4)
90
112.912(3)
90
3540.9(12)
8
1.722
9.5418(10)
12.7287(14)
13.6727(15)
100.0210(10)
102.4920(10)
109.9180(10)
1467.8(3)
1
β [°]
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3]
1.670
1.710
µ [mm–1]
1.413
2.012
Crystal size [mm]
F(000)
0.20ϫ 0.16ϫ0.10
1296
0.18ϫ0.16ϫ0.14
1856
0.28ϫ0.20ϫ0.10
744
2θmax [°]
Reflections collected
50.02
13627
55.72
16082
50.06
8042
Independent reflections
Goodness-of-fit
4720
0.986
4218
1.028
5132
1.071
R
Rw
0.0400
0.0746
0.340/–0.312
0.0243
0.0580
0.388/–0.505
0.0321
0.0922
0.493/–0.496
Largest diff peak and hole [eÅ–3]
1126
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Eur. J. Inorg. Chem. 2010, 1119–1128

Diiron Thiadithiolate Complexes Related to the [FeFe]-Hydrogenases
Table 5. Crystal data and structure refinement details for 10–12.
10
11
12
Formula
C16H11BF4Fe3O8S3
681.79
C13H4CrFe2O11S3
596.04
C13H4Fe2O11S3W
727.89
Mr [gmol–1]
T [K]
Crystal system
Space group
293(2)
monoclinic
P21/c
293(2)
monoclinic
C2/c
293(2)
monoclinic
C2/c
a [Å]
b [Å]
c [Å]
α [°]
21.903(8)
7.456(3)
15.189(5)
90
29.648(9)
9.633(3)
14.589(4)
90
29.871(9)
9.697(3)
14.750(5)
90
β [°]
99.374(6)
90
2447.6(15)
4
1.850
2.080
94.644(5)
90
4153(2)
8
1.907
2.247
95.114(6)
90
4256(2)
8
2.272
7.084
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3]
µ [mm–1]
Crystal size [mm]
F(000)
0.18ϫ0.14ϫ0.08
1352
0.24ϫ0.20ϫ0.16
2352
0.16ϫ0.12ϫ0.08
2752
2θmax [°]
Reflections collected
52.54
13464
50.02
9905
52.86
12022
Independent reflections
Goodness-of-fit
4880
1.065
3650
0.982
4368
0.967
R
Rw
0.0349
0.0710
0.455/–0.453
0.0381
0.0567
0.347/–0.312
0.0363
0.0578
0.979/–0.955
Largest diff peak and hole [eÅ–3]
the CRYSTALCLEAR program.[33] The structures were solved by
direct methods with the SHELXS-97 program[34] and refined by
full-matrix least-squares techniques (SHELXL-97)[35] on F2. Hy-
drogen atoms were located by using the geometric method. Details
of the crystal data, data collections, and structure refinements are
summarized in Tables 4 and 5. CCDC-745905 for 1, –745906 for
3, –745907 for 8, –745908 for 10, –745909 for 11, and –745910 for
12 contain the supplementary crystallographic data. These data can
be obtained free of charge from the Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data-request /cif.
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China and the Research Fund for the Doctoral Program of Higher
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Received: October 23, 2009
Published Online: January 21, 2010
1128
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 1119–1128