Synthesis, structure, and electrocatalysis of diiron C-functionalized propanedithiolate (PDT) complexes related to the active site of [FeFe]-hydrogenases

Article abstract of DOI:10.1021/ic701982z

New C-functionalized propanedithiolate-type model complexes (1-8) have been synthesized by functional transformation reactions of the known complex [(μ-SCH₂)₂CH(OH)]Fe₂(CO)₆ (A). Treatment of A with the acylating agents PhC(O)Cl, 4-pyridinecarboxylic acid chloride, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in the presence of Et₃N affords the expected C-functionalized complexes [(μ-SCH₂)₂CHO₂CPh]Fe₂(CO) ₆ (1), [(μ-SCH₂)₂CHO₂CC ₅H₄N-4]Fe₂(CO)₆ (2), [(μ-SCH ₂)₂CHO₂CC₄H₃O-2]Fe ₂(CO)₆ (3), and [(μ-SCH₂) ₂CHO₂CC₄H₃S-2]Fe₂(CO) ₆ (4). However, when A is treated with the phosphatizing agents Ph₂PCl, PCl₃ and PBr₃, both C- and Fe-functionalized complexes [(μ-SCH₂)₂CHOPPh ₂-η¹]Fe₂(CO)₅ (5), [(μ-SCH₂)₂CHOPCl₂-η¹]Fe ₂(CO)₅ (6), and [(μ-SCH₂) ₂CHOPBr₂-η¹]Fe₂(CO)₅ (7) are unexpectedly obtained via intramolecular CO substitution by P atoms of the initially formed phosphite complexes. The simplest C-functionalized model complex [(μ-SCH₂)₂C=O]Fe₂(CO)₆ (8) can be produced by oxidation of A with Dess-Martin reagent. While 8 is found to be an electrocatalyst for proton reduction to hydrogen, starting complex A can be prepared by another method involving the reaction of HC(OH)(CH ₂Br)₂ with the in situ generated (μ-LiS) ₂Fe₂(CO)₆. X-ray crystallographic studies reveal that the bridgehead C atom of 8 is double-bonded to an O atom to form a ketone functionality, whereas the bridgehead C atoms of A, 1, 3, and 4 are equatorially-bonded to their functionalities and those of 5-7 axially-bonded to their functionalities due to formation of the corresponding P-Fe bond-containing heterocycles.

Full text of DOI:10.1021/ic701982z

Inorg. Chem. 2008, 47, 4545-4553
Synthesis, Structure, and Electrocatalysis of Diiron C-Functionalized
Propanedithiolate (PDT) Complexes Related to the Active Site of
[FeFe]-Hydrogenases
Li-Cheng Song,* Chang-Gong Li, Jie Gao, Bang-Shao Yin, Xiang Luo, Xiao-Guang Zhang,
Hai-Lin Bao, and Qing-Mei Hu
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai
UniVersity, Tianjin 300071, China
Received October 8, 2007
New C-functionalized propanedithiolate-type model complexes (1-8) have been synthesized by functional
transformation reactions of the known complex [(µ-SCH2)2CH(OH)]Fe2(CO)6 (A). Treatment of A with the acylating
agents PhC(O)Cl, 4-pyridinecarboxylic acid chloride, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in
the presence of Et3N affords the expected C-functionalized complexes [(µ-SCH2)2CHO2CPh]Fe2(CO)6 (1), [(µ-
SCH2)2CHO2CC5H4N-4]Fe2(CO)6 (2), [(µ-SCH2)2CHO2CC4H3O-2]Fe2(CO)6 (3), and [(µ-SCH2)2CHO2CC4H3S-2]Fe2(CO)6
(4). However, when A is treated with the phosphatizing agents Ph2PCl, PCl3 and PBr3, both C- and Fe-functionalized
1
1
complexes [(µ-SCH2)2CHOPPh2-η ]Fe2(CO)5 (5), [(µ-SCH2)2CHOPCl2-η ]Fe2(CO)5 (6), and [(µ-SCH2)2CHOPBr2-
1
η ]Fe2(CO)5 (7) are unexpectedly obtained via intramolecular CO substitution by P atoms of the initially formed
phosphite complexes. The simplest C-functionalized model complex [(µ-SCH2)2CdO]Fe2(CO)6 (8) can be produced
by oxidation of A with Dess-Martin reagent. While 8 is found to be an electrocatalyst for proton reduction to
hydrogen, starting complex A can be prepared by another method involving the reaction of HC(OH)(CH2Br)2 with
the in situ generated (µ-LiS)2Fe2(CO)6. X-ray crystallographic studies reveal that the bridgehead C atom of 8 is
double-bonded to an O atom to form a ketone functionality, whereas the bridgehead C atoms of A, 1, 3, and 4 are
equatorially-bonded to their functionalities and those of 5-7 axially-bonded to their functionalities due to formation
of the corresponding P-Fe bond-containing heterocycles.
Introduction
Combined studies of X-ray crystallography9–11 and FTIR
spectroscopy12–14 demonstrated that [FeFe]-hydrogenases
contain a structurally uncommon active site (so-called
H-cluster), which is composed of a butterfly [2Fe2S] cluster
with one of its iron atoms connected to a cubane-like [4Fe4S]
cluster via the sulfur atom of a cysteinyl ligand. In addition,
Hydrogenases are a class of natural enzymes that can
catalyze H2 metabolism in several microorganisms.1,2 Ac-
cording to the metal content, they are generally classified as
[FeFe]-hydrogenases, [NiFe]-hydrogenases, and [Fe]-hydro-
genases (Hmd).3,4 Among these types of hydrogenases,
[FeFe]-hydrogenases have recently received much more
attention than the other two, largely due to their unusual
structure and particularly their extremely high capability for
production of “clean” and highly efficient hydrogen fuel.5–8
(7) Alper, J. Science 2003, 299, 1686.
(8) Song, L.-C. Acc. Chem. Res. 2005, 38, 21.
(9) Peters, J. W.; Lanzilotta, W. N.; Lemon, B. J.; Seefeldt, L. C. Science
1998, 282, 1853.
(10) Nicolet, Y.; Piras, C.; Legrand, P.; Hatchikian, C. E.; Fontecilla-Camps,
J. C. Structure 1999, 7, 13.
* To whom correspondence should be addressed. E-mail: lcsong@
nankai.edu.cn. Fax: 0086-22-23504853.
(11) Nicolet, Y.; De Lacey, A. L.; Verne`de, X.; Fernandez, V. M.;
Hatchikian, E. C.; Fontecilla-Camps, J. C. J. Am. Chem. Soc. 2001,
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Natl. Acad. Sci. U.S.A. 2003, 100, 3683.
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Fernandez, V. M. J. Am. Chem. Soc. 2000, 122, 11232.
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10.1021/ic701982z CCC: $40.75  2008 American Chemical Society
Inorganic Chemistry, Vol. 47, No. 11, 2008 4545
Published on Web 04/26/2008

Song et al.
Scheme 1
However, we recently found a method by which A can be
conveniently prepared with a moderate yield. That is, the
treatment of (µ-LiS)2Fe2(CO)6 (prepared from (µ-S2)Fe2(CO)6
and Et3BHLi)30 with 1,3-dibromo-2-propanol resulted in the
formation of A in 42% yield (Scheme 2). The structure of
A obtained by this method has been fully characterized by
elemental analysis, spectroscopy, and X-ray crystallography.
For example, the IR spectrum of A showed five absorption
bands in the range 2078-1973 cm-1 for its terminal
carbonyls and one broad band at 3302 cm-1 for its hydroxy
group. The 1H NMR spectrum displayed a multiplet around
3.10 ppm for the hydrogen atom attached to its bridgehead
C atom, and it displayed a triplet at 1.50 ppm and a doublet/
doublet at 2.79 ppm for the axial and the equatorial
hydrogens in its two CH2S groups, respectively. The crystal
structure of A determined by X-ray diffraction analysis
contains 0.5 CHCl3 molecules per molecule of A.31 While
Figure 1 shows its ORTEP plot, Table 1 lists its selected
bond lengths and angles. As can be seen in Figure 1, complex
A contains a hydroxylpropanedithiolate ligand, which is
bridged between two Fe atoms of the diiron subsite to form
two fused six-membered rings Fe1S1C7C8C9S2 and
Fe2S1C7C8C9S2. The hydroxyl group and the hydrogen
atom attached to the bridgehead C8 atom reside in the
common equatorial and axial positions of the above-
mentioned chair and boat-shaped six-membered rings, re-
spectively. In addition, the Fe-Fe bond length of our A
(2.5164 Å) is actually the same as that reported (2.524 Å)31
and is very close to those reported for similar diiron carbonyl
complexes.23,28,32
the two iron atoms of the [2Fe2S] cluster are connected to
CO and CN- ligands and are bridged by a dithiolate
SCH2XCH2S cofactor (Scheme 1). This structural informa-
tion has encouraged chemists to synthesize a wide variety
of H-cluster models.15–28 Among these models, the C-
functionalized propanedithiolate (PDT) and the N-function-
alized azadithiolate (ADT) models are of particular interest,
since they could be easily modified by functional transforma-
tion reactions to get a variety of biomimetic analogues with
novel structure and improved catalytic properties.18,19,26 In
this paper, we report the synthesis, structural characterization,
and properties of a new series of C-functionalized PDT
models obtained by functional transformation reactions of
the known complex [(µ-SCH2)2CH(OH)]Fe2(CO)6 (A).29 In
addition, a new synthetic method for complex A and the
biomimetic H2 evolution catalyzed by one of the new models
are also described.
Results and Discussion
Synthesis and Characterization of Starting Complex
[(µ-SCH2)2CH(OH)]Fe2(CO)6 (A). Since 1982, when Hutt-
ner first prepared complex A by oxidative addition method
of Fe3(CO)12 with dithiol HSCH2CH(OH)CH2SH,29 no other
synthetic method for this complex has been reported.
Synthesis and Characterization of Model Complexes
[(µ-SCH2)2CHO2CPh]Fe2(CO)6
(1),
[(µ-SCH2)2-
CHO2CC5H4N-4]Fe2(CO)6 (2), [(µ-SCH2)2CHO2CC4H3O-
2]Fe2(CO)6 (3), and [(µ-SCH2)2CHO2CC4H3S-2]Fe2(CO)6
(4). The C-functionalized PDT-type models 1-4 were
prepared via functional transformation reactions of the
C-hydroxyl group of complex A. Thus, acylation of A with
benzoyl chloride or 4-pyridinecarboxylic acid chloride in
CH2Cl2 in the presence of Et3N gave the expected C-benzoate
and C-pyridinecarboxylate complexes 1 and 2 in 63% and
61% yields, respectively, whereas A reacted with 2-furan-
carbonyl chloride or 2-thiophenecarbonyl chloride under
similar conditions to afford the corresponding C-furancar-
boxylate and C-thiophenecarboxylate complexes 3 and 4 in
70% and 58% yields, respectively (Scheme 3).
Complexes 1-4 are air-stable red solids, which have been
characterized by elemental analysis and spectroscopy. The
IR spectra of 1-4 displayed five to six absorption bands in
the region 2076-1937 cm-1 for their terminal carbonyls and
one absorption band in the range 1735-1718 cm-1 for their
ester carbonyls. The 1H NMR spectra of 1-4 showed a broad
(15) Gloaguen, F.; Lawrence, J. D.; Schmidt, M.; Wilson, S. R.; Rauchfuss,
T. B. J. Am. Chem. Soc. 2001, 123, 12518.
(16) Lyon, E. J.; Georgakaki, I. P.; Reibenspies, J. H.; Darensbourg, M. Y.
J. Am. Chem. Soc. 2001, 123, 3268.
(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.
(18) Tard, C.; Liu, X.; Ibrahim, S. K.; Bruschi, M.; De Gioia, L.; Davies,
S. C.; Yang, X.; Wang, L.-S.; Sawers, G.; Pickett, C. J. Nature 2005,
433, 610.
(19) Thomas, C. M.; Ru¨diger, O.; Liu, T.; Carson, C. E.; Hall, M. B.;
Darensbourg, M. Y. Organometallics 2007, 26, 3976.
(20) Gloaguen, F.; Lawrence, J. D.; Rauchfuss, T. B. J. Am. Chem. Soc.
2001, 123, 9476.
(21) Capon, J.-F.; Hassnaoui, S. E.; Gloaguen, F.; Schollhammer, P.;
Talarmin, J. Organometallics 2005, 24, 2020.
(22) Adam, F. I.; Hogarth, G.; Richards, I.; Sanchez, B. E. Dalton Trans.
2007, 2495.
(23) Lawrence, J. D.; Li, H.; Rauchfuss, T. B. Chem. Commun. 2001, 1482.
(24) Lawrence, J. D.; Li, H.; Rauchfuss, T. B.; Be´nard, M.; Rohmer, M.-
M. Angew. Chem., Int. Ed. 2001, 40, 1768.
(25) Song, L.-C.; Ge, J.-H.; Zhang, X.-G.; Liu, Y.; Hu, Q.-M. Eur. J. Inorg.
Chem. 2006, 3204.
(26) (a) Song, L.-C.; Tang, M.-Y.; Su, F.-H.; Hu, Q.-M. Angew. Chem.,
Int. Ed. 2006, 45, 1130. (b) Song, L.-C.; Tang, M.-Y.; Mei, S.-Z.;
Huang, J.-H.; Hu, Q.-M. Organometallics 2007, 26, 1575.
(27) Song, L.-C.; Yang, Z.-Y.; Bian, H.-Z.; Liu, Y.; Wang, H.-T.; Liu,
X.-F.; Hu, Q.-M. Organometallics 2005, 24, 6126.
(30) Seyferth, D.; Henderson, R. S.; Song, L.-C. J. Organomet. Chem. 1980,
192, C1.
(28) (a) Song, L.-C.; Yang, Z.-Y.; Hua, Y.-J.; Wang, H.-T.; Liu, Y.; Hu,
Q.-M. Organometallics 2007, 26, 2106. (b) Song, L.-C.; Yin, B.-S.;
Li, Y.-L.; Zhao, L.-Q.; Ge, J.-H.; Yang, Z.-Y.; Hu, Q.-M. Organo-
metallics 2007, 26, 4921.
(31) During the review of this submission another crystal structure of A
with 0.5 CH2Cl2 was reported, see: Apfel, U.-P.; Halpin, Y.; Go¨rls,
H.; Vos, J. G.; Schweizer, B.; Linti, G.; Weigand, W. Chem. BiodiVers.
2007, 4, 2138.
(29) Winter, A.; Zsolnai, L.; Huttner, G. Z. Naturforsch., B: Anorg. Chem.,
Org. Chem. 1982, 37, 1430.
(32) Lyon, E. J.; Georgakaki, I. P.; Reibenspies, J. H.; Darensbourg, M. Y.
Angew. Chem., Int. Ed. 1999, 38, 3178.
4546 Inorganic Chemistry, Vol. 47, No. 11, 2008

Synthesis, Structure, and Electrocatalysis of PDT Complexes
Scheme 2
Table 1. Selected Bond Lengths (Å) and Angles (deg) for A, 1, 3, and 4
singlet or a multiplet around 4.50 ppm for their bridgehead
C-attached axial hydrogen atoms, and they showed a triplet
at approximately 1.70 ppm and a doublet/doublet or simply
a doublet at approximately 2.90 ppm for the axial and
equatorial hydrogens in their two CH2S groups.
The molecular structures of 1, 3, and 4 were unambigu-
ously confirmed by X-ray diffraction techniques (Figures 2–4
and Table 1). As can be seen intuitively from Figures 2–4,
complexes 1, 3, and 4 much resemble complex A containing
a benzoate, a furancarboxylate, or a thiophenecarboxylate
functionality equatorially attached to the bridgehead C8 atom
of the corresponding two fused six-membered rings, and the
hydrogen atom attached to the bridgehead C8 is in the axial
position of the two fused six-membered rings. The Fe-Fe
bond lengths of 1, 3, and 4 (2.4973-2.5088 Å) are very close
to those of A and the analogous diiron dithiolate com-
plexes.23,28,32
A
Fe(1)-S(1)
2.258(2)
2.263(2)
2.5164(14)
2.2582(19)
85.30(7)
56.14(5)
56.30(6)
85.24(7)
Fe(2)-S(2)
2.266(2)
1.481(8)
1.433(8)
1.427(7)
56.14(5)
56.20(6)
67.72(6)
119.7(7)
Fe(1)-S(2)
C(7)-C(8)
Fe(1)-Fe(2)
Fe(2)-S(1)
S(1)-Fe(1)-S(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(2)-S(2)
C(8)-C(9)
O(7)-C(8)
S(1)-Fe(2)-Fe(1)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
C(9)-C(8)-C(7)
1
3
4
Fe(1)-S(1)
2.2401(11)
2.2416(10)
2.4973(8)
2.2481(11)
85.51(3)
56.34(3)
56.45(3)
67.62(3)
Fe(2)-S(2)
2.2527(11)
1.500(4)
1.502(4)
1.453(4)
67.51(3)
85.07(4)
56.04(3)
114.5(3)
Fe(1)-S(2)
C(7)-C(8)
Fe(1)-Fe(2)
Fe(2)-S(1)
S(1)-Fe(1)-S(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(1)-Fe(2)
Fe(1)-S(1)-Fe(2)
C(8)-C(9)
O(7)-C(8)
Fe(1)-S(2)-Fe(2)
S(1)-Fe(2)-S(2)
S(1)-Fe(2)-Fe(1)
C(9)-C(8)-C(7)
Fe(1)-S(1)
2.2549(6)
2.2609(7)
2.5088(5)
2.2517(7)
85.00(2)
56.232(17)
56.380(19)
67.656(18)
Fe(2)-S(2)
2.2535(7)
1.469(2)
1.349(2)
Fe(1)-S(2)
O(7)-C(8)
Synthesis and Characterization of Model Complexes
Fe(1)-Fe(2)
O(7)-C(10)
[(µ-SCH2)2CHOPPh2-η1]Fe2(CO)5 (5), [(µ-SCH2)2-
Fe(2)-S(1)
O(8)-C(10)
1.207(2)
CHOPCl2-η1]Fe2(CO)5
(6),
[(µ-SCH2)2CHOPBr2-
S(2)-Fe(1)-S(1)
S(1)-Fe(2)-Fe(1)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(2)-S(1)
C(8)-O(7)-C(10)
56.097(19)
56.112(19)
85.25(2)
η1]Fe2(CO)5 (7), and [(µ-SCH2)2CdO]Fe2(CO)6 (8). The
C-functionalized PDT-type models 5-8 could also be
prepared by functional transformation reactions of complex
A. The C-diphenylphosphite complex 5, in which its P atom
is coordinated to one Fe atom of the diiron subsite, was
unexpectedly produced by the reaction of A with Ph2PCl in
the presence of Et3N in 48% yield; this reaction is most likely
to proceed via intermolecular condensation of A with the
phosphatizing agent Ph2PCl to give the initially formed
phosphite complex M1 and then the intramolecular CO
116.51(14)
Fe(1)-S(1)
2.2495(5)
2.2467(5)
2.5028(4)
2.2517(5)
85.672(15)
56.557(12)
56.262(13)
85.274(16)
Fe(2)-S(2)
2.2614(5)
Fe(1)-S(2)
O(7)-C(8)
1.4600(17)
1.3528(18)
1.1996(18)
55.999(14)
67.562(15)
67.444(14)
116.25(12)
Fe(1)-Fe(2)
Fe(2)-S(1)
S(2)-Fe(1)-S(1)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(1)-Fe(2)
S(1)-Fe(2)-S(2)
O(7)-C(10)
O(8)-C(10)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
Fe(1)-S(2)-Fe(2)
C(8)-O(7)-C(10)
substitution of M1 by its P atom (Scheme 4). As the
analogues of 5, dichloro- and dibromophosphite complexes
6 and 7 were similarly prepared in approximately 73% yield
by condensation of A with PX3 to give intermediates M2
and M3 followed by intramolecular CO substitution of these
intermediates by their P atoms (Scheme 4). The bridgehead
CdO functionality-containing model complex 8 was obtained
in 40% yield by oxidation of the bridgehead C-hydroxyl
group using Dess-Martin reagent (periodinane) (Scheme
4).33
Complexes 5-8 are red solids and have been characterized
by elemental analysis, spectroscopy, and X-ray crystal-
lography. The IR spectra of 5-8 displayed three to five
absorption bands in the region 2077-1934 cm-1 for their
terminal carbonyls, and 8 exhibited an additional band at
1
1700 cm-1 for its bridgehead CdO functionality. The H
NMR spectra of 5-7 showed two doublets at approximately
(33) Dess, D. B.; Martin, J. C. J. Org. Chem. 1983, 48, 4155.
Inorganic Chemistry, Vol. 47, No. 11, 2008 4547
Figure 1. Molecular structure of A with 30% probability level ellipsoids.

Song et al.
Scheme 3
2.0 and 2.8 ppm for the axial and equatorial hydrogen atoms
in their two CH2S groups, whereas the spectrum of 8
displayed only one singlet at 2.86 ppm for the hydrogen
atoms in its two CH2S groups because of rapid folding of
the two fused six-membered FeS2C3 rings.24 In addition, the
31P NMR spectra of 5-7 showed a singlet in the range
158-198 ppm for their P atoms coordinated to one Fe atom
of the diiron subsite.
X-ray crystallography (Figures 5–8 and Table 2) reveals
that (i) the structures of 5-7 are very similar to each other,
with all containing a phosphite-functionalized PDT ligand
attached to Fe(CO)3 and Fe(CO)2 units to form three six-
membered rings; (ii) the hydrogen atoms attached to the
bridgehead C atoms of 5-7, in contrast to those of A, 1, 3,
and 4, are in an equatorial position due to formation of the
P-Fe bond-containing six-membered heterocycles; (iii) in
contrast to A, 1, and 3-7, complex 8 has no hydrogen atom
attached to its bridgehead C atom, but instead, one oxygen
atom is double-bonded to its bridgehead C to form a ketone
carbonyl C8dO7 (1.214 Å); and (iv) the Fe-Fe bond lengths
of 5-8 (2.4929-2.5336 Å) are very close to those of A, 1,
3, and 4 but are somewhat shorter than those of the natural
enzymes (2.55-2.62 Å).9–11 It is worth pointing out that the
[2Fe2SP] models 5-7 are structurally very similar to the
[2Fe3S] model complexes reported by Pickett and Rauch-
fuss.17,23
Electrochemical Properties of 3, 4, and 8 and Electro-
catalytic H2 Production Catalyzed by 8. The electrochemi-
cal properties of 3, 4, and 8 were investigated by cyclic
voltammetry (CV) in MeCN under CO atmosphere. Table 3
lists their electrochemical data, whereas Figure 9 shows their
Figure 2. Molecular structure of 1 with 30% probability level ellipsoids.
4548 Inorganic Chemistry, Vol. 47, No. 11, 2008
Figure 3. Molecular structure of 3 with 30% probability level ellipsoids.

Synthesis, Structure, and Electrocatalysis of PDT Complexes
in Figure 10, and for comparison, the cyclic voltammogram
of 8 without CF3CO2H is also included. As shown in Figure
10, upon the first addition of 1 mM CF3CO2H to the solution
of 8, the original first reduction peak at -1.52 V considerably
increased and continued to grow up with sequential addition
of the acid. Apparently, this features an electrocatalytic
proton reduction process.20,25,36–38 This electrocatalytic H2
production was further proved by the bulk electrolysis of a
MeCN solution of 8 (0.5 mM) with CF3CO2H (25 mM) at
-1.80 V. During 0.5 h of the bulk electrolysis, 13.5 F per
mole of 8 were passed, which corresponds to 6.7 turnovers.
In such a large-scale experiment, H2 bubbles are evident.
Gas chromatography (GC) analysis showed that the hydrogen
yield was >90%.
Conclusion
On the basis of preparing known complex A by a
convenient new method, we have synthesized a series of
C-functionalized PDT-type models (1-8) by functional
transformation reactions of complex A. While 1-4 are the
C-functionalized models bearing different aromatic carboxy-
late functionalities, 5-7 contain different C-phosphite moi-
eties concurrently coordinated via their P atoms to one Fe
atom of their diiron subsites. The simplest one of this series,
namely 8, is the bridgehead ketone derivative of complex
A. All the new model complexes have been characterized
by elemental analysis and spectroscopy, as well as, for
starting complex A and model complexes 1 and 3-8, by
X-ray diffraction analyses. Model 8 is found to be a catalyst
for proton reduction to H2 under electrochemical conditions.
It is interesting to note that the phosphite-containing [2Fe2SP]
model complexes 5-7 are structurally very similar to those
[2Fe3S] models previously reported by the Pickett and
Rauchfuss groups.17,23
Figure 4. Molecular structure of 4 with 30% probability level ellipsoids.
cyclic voltammograms. It is shown that the first reductions
of the three models (Epc ) -1.52 to -1.59 V) are irreversible
one-electron processes, which could be attributed to the
FeIFeI/FeIFe0 couple. The second reductions of the three
models (Epc ) -2.21 to -2.39 V) and their oxidations (Epa
) +0.84 to +1.01 V) are also irreversible one-electron
processes, which could be ascribed to the FeIFe0/Fe0Fe0 and
FeIFeI/FeIFeII couples, respectively. The one-electron assign-
ments for the aforementioned reduction and oxidation
processes were supported by the calculated value of 0.95
faraday/equiv (obtained through the study of the bulk
electrolysis of a MeCN solution of 8 at -1.71 V) and the
calculated value of (ip/ν1/2)/(it1/2) ) 3.90 (obtained through
the study of CV and chronoamperometry (CA) of 8).34 In
addition, the irreversible processes were assigned according
to the Ipa/Ipc and ∆Ep (peak to peak separation) values of the
corresponding redox events.34 The cyclic voltammograms
of 8 with CF3CO2H (pKa ) 12.7 in MeCN)35 are presented
Experimental Section
General Comments. All reactions were performed using stan-
dard Schlenk and vacuum-line techniques under N2 atmosphere.
Scheme 4
Inorganic Chemistry, Vol. 47, No. 11, 2008 4549

Song et al.
Figure 5. Molecular structure of 5 with 30% probability level ellipsoids.
Figure 6. Molecular structure of 6 with 30% probability level ellipsoids.
Figure 8. Molecular structure of 8 with 30% probability level ellipsoids.
ride (2-C4H3OC(O)Cl),41 thiophenecarbonyl chloride (2-C4H3SC-
(O)Cl),42 and Dess-Martin reagent (periodinane)43 were prepared
according to the literature procedures. Preparative thin-layer chro-
matography (TLC) was carried out on glass plates (26 × 20 ×
0.25 cm3) coated with silica gel G (10-40 µm). IR spectra were
recorded on a Bio-Rad FTS 6000 spectrophotometer. 1H NMR and
31P NMR spectra were obtained on a Bruker Avance 300 or a Varian
Mercury Plus 400 spectrometer. Elemental analyses were performed
on an Elementar Vario EL analyzer. Melting points were determined
on a Yanaco MP-500 apparatus and were uncorrected.
Preparation of [(µ-SCH2)2CH(OH)]Fe2(CO)6 (A). A red solu-
tion of (µ-S)2Fe2(CO)6 (0.172 g, 0.50 mmol) in THF (10 mL) was
(36) Chong, D.; Georgakaki, I. P.; Mejia-Rodriguez, R.; Sanabria-
Chinchilla, J.; Soriaga, M. P.; Darensbourg, M. Y. Dalton Trans. 2003,
4158.
Figure 7. Molecular structure of 7 with 30% probability level ellipsoids.
(37) Mejia-Rodriguez, R.; Chong, D.; Reibenspies, J. H.; Soriaga, M. P.;
Darensbourg, M. Y. J. Am. Chem. Soc. 2004, 126, 12004.
(38) Bhugun, I.; Lexa, D.; Save´ant, J.-M. J. Am. Chem. Soc. 1996, 118,
3982.
(39) Seyferth, D.; Henderson, R. S.; Song, L.-C. Organometallics 1982,
1, 125.
(40) Meyers, A. I.; Gabel, R. A. J. Org. Chem. 1982, 47, 2633.
(41) Chadwick, D. J.; McKnight, M. V.; Ngochindo, R. J. Chem. Soc.,
Perkin Trans. 1 1982, 1343.
Dichloromethane and THF were distilled over CaH2 and sodium/
benzophenone ketyl under N2, respectively. (BrCH2)2CHOH (85%,
d ) 2.13), Et3BHLi (1 M in THF), PhC(O)Cl, Ph2PCl, PCl3, PBr3,
and triethylamine were available commercially and used as received.
(µ-S)2Fe2(CO)6,39 4-C5H4NC(O)Cl · HCl,40 furancarbonyl chlo-
(34) Zanello, P. Inorganic Electrochemistry. Theory, Practice and Ap-
plication; Thomas Graham House: Cambridge, U.K., 2003.
(35) Izutsu, K. Acid-Base Dissociation Constants in Dipolar Aprotic
SolVents; Blackwell Scientific Publications: Oxford, U.K., 1990.
(42) Carpenter, A. J.; Chadwick, D. J. J. Chem. Soc., Perkin Trans. 1 1985,
173.
(43) Hart, D. S. Organic Syntheses; Wiley: Hoboken, NJ, 2004; Vol. 10,
p 696.
4550 Inorganic Chemistry, Vol. 47, No. 11, 2008

Synthesis, Structure, and Electrocatalysis of PDT Complexes
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 5-8
5
Fe(1)-S(2)
2.2479(12)
2.4929(9)
2.2596(13)
2.2560(13)
86.55(4)
56.42(4)
56.20(3)
67.02(4)
P(1)-O(6)
1.621(3)
2.1751(13)
1.821(4)
1.820(4)
56.66(3)
56.56(3)
86.18(5)
95.16(4)
Fe(1)-Fe(2)
Fe(1)-P(1)
Fe(2)-S(1)
Fe(1)-S(1)
S(2)-Fe(1)-S(1)
S(1)-Fe(2)-Fe(1)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
P(1)-C(9)
P(1)-C(15)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(2)-S(1)
P(1)-Fe(1)-S(1)
6
7
8
Fe(1)-S(1)
2.2533(10)
2.2519(10)
2.5336(8)
2.2542(9)
86.46(4)
55.78(3)
55.77(2)
68.40(3)
Fe(2)-S(2)
2.2517(9)
1.6037(17)
2.1160(11)
2.0411(11)
55.76(3)
55.82(2)
86.44(4)
134.27(3)
Fe(1)-S(2)
P(1)-O(6)
Fe(1)-Fe(2)
Fe(2)-S(1)
S(1)-Fe(1)-S(2)
S(1)-Fe(2)-Fe(1)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
Fe(2)-P(1)
P(1)-Cl(1)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(1)-Fe(2)
S(1)-Fe(2)-S(2)
P(1)-Fe(2)-Fe(1)
Figure 10. Cyclic voltammograms of 8 (1.0 mM) with CF3CO2H (0-4
mM) in 0.1 M n-Bu4NPF6/MeCN at a scan rate of 100 mV s-1
.
(v/v ) 3:1) as eluent. From the major red band, A was obtained as
a red solid (0.085 g, 42%), mp 102-104 °C. Anal. Calcd for
C9H6Fe2O7S2: C, 26.89; H, 1.50. Found: C, 26.79; H, 1.33. IR (KBr
disk): νCtO 2078 (s), 2036 (vs), 2009 (vs), 1990 (vs), 1973 (vs);
Fe(1)-S(1)
2.2423(15)
2.2435(15)
2.5125(11)
2.2420(16)
85.86(6)
55.92(4)
55.85(4)
85.95(6)
Fe(2)-S(2)
2.2401(16)
1.594(4)
2.1072(16)
2.2154(16)
55.98(4)
85.95(6)
68.15(5)
91.23(6)
Fe(1)-S(2)
P(1)-O(6)
Fe(1)-Fe(2)
Fe(1)-P(1)
Fe(2)-S(1)
Br(1)-P(1)
S(1)-Fe(1)-S(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(1)-Fe(2)
S(2)-Fe(2)-S(1)
S(2)-Fe(2)-Fe(1)
S(1)-Fe(2)-S(2)
Fe(1)-S(1)-Fe(2)
P(1)-Fe(1)-S(2)
1
νOsH 3302 (m) cm-1. H NMR (300 MHz, CDCl3): 1.50 (t, 2Ha,
JHaHe ) JHaHa′ ) 12.0 Hz), 1.79 (br s, 1H, OH), 2.79 (dd, 2He,
JHeHa ) 12.9 Hz, JHeHa′ ) 3.9 Hz), 3.06-3.17 (m, 1Ha′) ppm (In
this paper Ha and He denote the axially and equatorially bonded H
atoms in CH2S groups, while Ha′ and He′ represent those axially or
equatorially bonded to the bridgehead C atom).
Fe(1)-S(1)
2.2443(7)
2.2554(7)
2.5192(6)
2.2359(7)
85.58(2)
55.63(2)
55.778(19)
86.01(2)
Fe(2)-S(2)
2.2455(7)
1.502(3)
1.497(3)
1.214(3)
55.945(19)
56.150(19)
68.43(2)
116.5(2)
Fe(1)-S(2)
C(7)-C(8)
Fe(1)-Fe(2)
C(8)-C(9)
Preparation of [(µ-SCH2)2CHO2CPh]Fe2(CO)6 (1). To a
solution of A (0.200 g, 0.50 mmol) in CH2Cl2 (20 mL) cooled to
0 °C were added PhC(O)Cl (0.11 mL, 1.0 mmol) and Et3N (0.14
mL, 1.0 mmol). The mixture was allowed to warm to room
temperature and was stirred at this temperature for 2 h. Volatiles
were removed under vacuum, and the residue was subjected to TLC
using CH2Cl2/petroleum ether (v/v ) 2:3) as eluent. From the main
red band, 1 was obtained as a red solid (0.160 g, 63%), mp 128-130
°C. Anal. Calcd for C16H10Fe2O8S2: C, 37.97; H, 1.99. Found: C,
38.11; H, 2.08. IR (KBr disk): νCtO 2073 (s), 2037 (vs), 2003 (vs),
Fe(2)-S(1)
O(7)-C(8)
S(1)-Fe(1)-S(2)
S(1)-Fe(1)-Fe(2)
S(2)-Fe(1)-Fe(2)
S(1)-Fe(2)-S(2)
S(1)-Fe(2)-Fe(1)
S(2)-Fe(2)-Fe(1)
Fe(2)-S(1)-Fe(1)
C(9)-C(8)-C(7)
Table 3. Electrochemical Data of 3, 4, and 8a
Epc (V)
Epc (V)
Epa (V)
compd
FeIFeI/FeIFe0
FeIFe0/Fe0Fe0
FeIFeI/FeIFeII
3
4
8
-1.58
-1.59
-1.52
-2.21
-2.23
-2.39
+0.85
+0.84
+1.01
1
1984 (vs), 1973 (s); νCdO 1726 (s) cm-1. H NMR (400 MHz,
CDCl3): 1.70 (t, 2Ha, JHaHe ) JHaHa′ ) 12.4 Hz), 2.93 (dd, 2He,
JHeHa ) 12.8 Hz, JHeHa′ ) 4.4 Hz), 4.38-4.60 (m, 1Ha′), 7.40-7.95
(m, 5H, C6H5) ppm.
a All potentials are versus Fc/Fc+ in 0.1 M n-Bu4NPF6/MeCN.
Preparation of [(µ-SCH2)2CHO2CC5H4N-4]Fe2(CO)6 (2). The
same procedure was followed as that for the preparation of 1, but
4-C5H4NC(O)Cl·HCl (0.180 g, 1.0 mmol), Et3N (0.28 mL, 2.0
mmol), and CH2Cl2/acetone (v/v ) 100:1) were used in place of
the corresponding materials. From the major red band, 2 was
obtained as a red solid (0.154 g, 61%), mp 188-190 °C. Anal.
Calcd for C15H9Fe2NO8S2: C, 35.53; H, 1.79; N, 2.76. Found: C,
35.52; H, 1.89; N, 2.83. IR (KBr disk): νCtO 2073 (s), 2038 (vs),
2012 (vs), 1992 (vs), 1978 (s); νCdO 1733 (s) cm-1. 1H NMR (400
MHz, CDCl3): 1.71 (t, 2Ha, JHaHe ) JHaHa′ ) 12.4 Hz), 2.92 (dd,
2He, JHeHa ) 12.8 Hz, JHeHa′ ) 4.0 Hz), 4.40-4.58 (m, 1Ha′), 8.36,
10.74 (2 br s, 4H, C5H4N) ppm.
Preparation of [(µ-SCH2)2CHO2CC4H3O-2]Fe2(CO)6 (3). A
solution of A (0.140 g, 0.35 mmol), 2-C4H3OC(O)Cl (0.40 mL,
4.1 mmol), and Et3N (0.70 mL, 5.0 mmol) in CH2Cl2 (10 mL) was
stirred at room temperature for 5 h. After removal of volatiles, the
residue was subjected to TLC using acetone/petroleum ether (v/v
) 1:2) as eluent. From the major red band, 3 was obtained as a red
solid (0.120 g, 70%), mp 112-114 °C. Anal. Calcd for
C14H8Fe2O9S2: C, 33.90; H, 1.63. Found: C, 33.80; H, 1.84. IR
(KBr disk): νCtO 2076 (s), 2035 (vs), 1997 (vs), 1979 (vs),1961
Figure 9. Cyclic voltammograms of 3, 4, and 8 (1.0 mM) in 0.1 M
n-Bu4NPF6/MeCN at a scan rate of 100 mV s-1
.
cooled to -78 °C and then treated dropwise with Et3BHLi (1.0
mL, 1.0 mmol) to give a green solution. After stirring for 15 min,
1,3-dibromo-2-propanol (0.06 mL, 0.50 mmol) was added. The
mixture was allowed to warm to room temperature and was stirred
at this temperature for 2 h. Volatiles were removed under vacuum,
and the residue was subjected to TLC using CH2Cl2/petroleum ether
1
(s), 1937 (m); νCdO 1735 (s) cm-1. H NMR (300 MHz, CDCl3):
Inorganic Chemistry, Vol. 47, No. 11, 2008 4551

Song et al.
Table 4. Crystal Data and Structure Refinement Details for A, 1, 3, and 4
A
1
3
4
mol formula
mol wt
cryst syst
space group
a/Å
2 (C9H6Fe2O7S2) CHCl3
923.28
monoclinic
P2(1)/n
15.122(4)
6.9241(18)
32.378(9)
90
99.132(5)
90
3347.2(15)
4
1.832
2.247
1832
C16H10Fe2O8S2
506.06
monoclinic
P2(1)/c
13.802(3)
8.4531(17)
17.059(4)
90
96.649(4)
90
1977.0(7)
4
1.700
1.719
1016
C14H8Fe2O9S2
496.02
C14H8Fe2O8S3
512.08
triclinic
monoclinic
P121/c1
13.5497(17)
8.2687(10)
16.800(3)
90
98.085(5)
90
1863.5(4)
4
j
P1
8.7846 (16)
9.121(2)
11.778(3)
78.677(8)
79.185(10)
76.766(10)
890.7(3)
2
b/Å
c/Å
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
Dc/g cm-3
abs coeff/mm-1
F(000)
1.850
1.909
496
1.825
1.932
1024
index ranges
-9 e h e 18
-8 e k e 8
-40 e l e 37
18218
-17 e h e 13
-9 e k e 10
-21 e l e 17
10846
-11 e h e 9
-11 e k e 11
-15 e l e 15
8309
-15 e h e 18
-11 e k e 10
-22 e l e 22
17664
rflns
indep rflns
6892
4030
4155
4791
2θmax/deg
R
53.06
0.0556
52.84
0.0386
55.70
0.0250
57.46
0.0245
Rw
0.0679
0.0641
0.0616
0.0575
GOF
0.981
0.451/-0.427
1.044
0.279/-0.351
0.964
0.437/-0.406
0.998
0.335/-0.375
largest diff peak and hole/e Å-3
Table 5. Crystal Data and Structure Refinement Details for 5-8
5
6
7
8
mol formula
mol wt
cryst syst
space group
a/Å
C20H15Fe2O6PS2
558.11
C8H5Cl2Fe2O6PS2
474.81
C8H5Br2Fe2O6PS2
563.73
monoclinic
P2(1)/c
13.127(3)
10.202(2)
12.752(3)
90
107.935(4)
90
1624.7(6)
4
2.305
7.077
1080
C9H4Fe2O7S2
399.94
monoclinic
P121/a1
11.799(3)
17.254(4)
12.113(3)
90
115.785(4)
90
2220.4(10)
4
monoclinic
P2(1)/n
6.619(3)
14.745(6)
16.380(7)
90
99.272(7)
90
1577.6(12)
4
monoclinic
P121/n1
17.259(3)
8.8183(12)
18.165(3)
90
100.805(2)
90
2715.7(7)
8
b/Å
c/Å
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
Dc/g cm-3
abs coeff/mm-1
F(000)
1.670
1.601
1128
1.999
2.561
936
1.956
2.468
1584
index ranges
-15 e h e 15
-22 e k e 22
-15 e l e 15
27647
-8 e h e 3
-18 e k e 18
-20 e l e 20
8957
-16 e h e 15
-12 e k e 12
-8 e l e 15
9103
-22 e h e 22
-11 e k e 8
-23 e l e 23
25097
rflns
indep rflns
5293
3221
3315
6482
2θmax /deg
R
55.76
0.0672
52.72
0.0260
52.80
0.0401
55.78
0.0293
Rw
0.1365
0.0595
0.0848
0.0715
GOF
1.188
0.566/-0.626
1.062
0.310/-0.484
0.989
0.749/-0.415
1.071
0.401/-0.423
largest diff peak and hole/e Å-3
1.72 (t, 2Ha, JHaHe ) JHaHa′ ) 11.7 Hz), 2.90 (dd, 2He, JHeHa
12.0 Hz, JHeHa′ ) 3.0 Hz), 4.51 (br s, 1Ha′), 6.51, 7.16, 7.57 (3s,
3H, C4H3O) ppm.
)
were added Et3N (0.035 mL, 0.25 mmol) and Ph2PCl (0.05 mL,
0.25 mmol). The new solution was allowed to warm to room
temperature and was stirred at this temperature overnight. After
removal of volatiles, the residue was subjected to TLC using
CH2Cl2/petroleum ether (v/v ) 1:2) as eluent. From the main red
band, 5 was obtained as a red solid (0.067 g, 48%), mp 177-178
°C. Anal. Calcd for C20H15Fe2O6PS2: C, 43.04; H, 2.71. Found: C,
43.05; H, 2.87. IR (KBr disk): νCtO 2047 (s), 1973 (vs), 1934 (s)
Preparation of [(µ-SCH2)2CHO2CC4H3S-2]Fe2(CO)6 (4). The
same procedure was followed as that for the preparation of 3, but
2-C4H3SC(O)Cl (0.44 mL, 4.1 mmol) was used instead of
2-C4H3OC(O)Cl. 4 was obtained as a red solid (0.103 g, 58%), mp
116-118 °C. Anal. Calcd for C14H8Fe2O8S3: C, 32.84; H, 1.57.
Found: C, 33.08; H, 1.38. IR (KBr disk): νCtO 2073 (s), 2036 (vs),
2001 (vs), 1981 (vs), 1948 (s); νCdO 1718 (s) cm-1. 1H NMR (300
MHz, CDCl3): 1.69 (t, 2Ha, JHaHe ) JHaHa′’ ) 11.4 Hz), 2.92 (d,
2He, JHeHa ) 11.1 Hz), 4.44 (br s, 1Ha′), 7.09, 7.58, 7.75 (3s, 3H,
C4H3S) ppm.
1
cm-1. H NMR (400 MHz, CDCl3): 1.94 (d, 2Ha, JHaHe ) 14.0
Hz), 2.65 (d, 2He, JHeHa ) 14.0 Hz), 4.98-5.03 (m, 1He′), 7.45-7.73
(m, 10H, 2C6H5) ppm. 31P NMR (162 MHz, CDCl3, 85% H3PO4):
158.33 (s) ppm.
Preparation of [(µ-SCH2)2CHOPCl2-η1]Fe2(CO)5 (6). To a red
solution of A (0.100 g, 0.25 mmol) in CH2Cl2 (10 mL) was added
PCl3 (0.022 mL, 0.25 mmol). The mixture was stirred at room
Preparation of [(µ-SCH2)2CHOPPh2-η1]Fe2(CO)5 (5). To a
solution of A (0.100 g, 0.25 mmol) in THF (5 mL) cooled to 0 °C
4552 Inorganic Chemistry, Vol. 47, No. 11, 2008

Synthesis, Structure, and Electrocatalysis of PDT Complexes
temperature for 6 h. Volatiles were removed under vacuum, and
the residue was subjected to TLC using CH2Cl2/petroleum ether
(v/v ) 1:3) as eluent. From the main red band, 6 was obtained as
a red solid (0.088 g, 74%), mp 136-138 °C. Anal. Calcd for
C8H5Cl2Fe2O6PS2: C, 20.24; H, 1.06. Found: C, 19.98; H, 1.19. IR
(KBr disk): νCtO 2063 (vs), 2019 (vs), 1992 (vs), 1973 (vs), 1943
(m) cm-1. 1H NMR (400 MHz, CDCl3): 1.98 (d, 2Ha, JHaHe ) 12.8
Hz), 2.81 (d, 2He, JHeHa ) 12.4 Hz), 5.2-5.25 (m,1He′) ppm. 31P
NMR (162 MHz, CDCl3, 85% H3PO4): 198.00 (s) ppm.
mounted on a Rigaku MM-007 (rotating anode) diffractometer
equipped with Saturn 70CCD. Data were collected at room
temperature, using a confocal monochromator with Mo KR radiation
(λ ) 0.71070 Å) in the ω-φ scanning mode. Data collection,
reduction, and absorption correction were performed by the
CRYSTALCLEAR program.45 All the structures were solved by
direct methods using the SHELXS-97 program46 and refined by
full-matrix least-squares techniques (SHELXL-97)47 on F2. Hy-
drogen atoms were located using the geometric method. The details
of crystal data, data collections, and structure refinements of A, 1,
3, and 4 and 5-8 are summarized in Tables 4 and 5, respectively.
Electrochemistry. Acetonitrile (Fisher Chemicals, HPLC grade)
was used in the electrochemical experiments. A solution of 0.1 M
n-Bu4NPF6 in MeCN was used as the electrolyte in all cyclic
voltammetric experiments. Electrochemical measurements were
made using a BAS Epsilon potentiostat. All voltammograms were
obtained in a three-electrode cell with a 3 mm diameter glassy
carbon working electrode, a platinum counter electrode, and a Ag/
Ag+ (0.01 M AgNO3/0.1 M n-Bu4NPF6 in MeCN) reference
electrode under CO atmosphere. The working electrode was
polished with 0.05 µm alumina 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 gastight H-type electrochemical cell containing
20 mL of MeCN. All potentials are quoted against the ferrocene/
ferrocenium (Fc/Fc+) potential. Gas chromatography was performed
with a Shimadzu gas chromatograph GC-9A under isothermal
conditions with nitrogen as a carrier gas and a thermal conductivity
detector.
Preparation of [(µ-SCH2)2CHOPBr2-η1]Fe2(CO)5 (7). The
same procedure was followed as that for the preparation of 6, but
PBr3 (0.024 mL, 0.25 mmol) was used in place of PCl3, and the
mixture was stirred for 4 h. From the main red band, 7 was obtained
as a red solid (0.101 g, 72%), mp 122 °C (dec). Anal. Calcd for
C8H5Br2Fe2O6PS2: C, 17.05; H, 0.89. Found: C, 17.09; H, 0.96. IR
1
(KBr disk): νCtO 2057 (vs), 2015 (vs), 1967 (vs). H NMR (300
MHz, CDCl3): 2.01 (d, 2Ha, JHaHe ) 15.0 Hz), 2.90 (d, 2He, JHeHa
) 14.5 Hz), 5.20-5.26 (m, 1He′) ppm. 31P NMR (162 MHz, CDCl3,
85% H3PO4): 162.92 (s) ppm.
Preparation of [(µ-SCH2)2CdO]Fe2(CO)6 (8). To a solution
of A (0.080 g, 0.20 mmol) in CH2Cl2 (10 mL) was added
Dess-Martin reagent (0.093 g, 0.22 mmol). The mixture was stirred
at room temperature for 0.5 h. Volatiles were removed under
vacuum, and the residue was subjected to TLC using CH2Cl2/
petroleum ether (v/v ) 1:1) as eluent. From the main red band, 8
was obtained as a red solid (0.032 g, 40%), mp 108-110 °C. Anal.
Calcd for C9H4Fe2O7S2: C, 27.03; H, 1.01. Found: C, 27.11; H,
1.29. IR (KBr disk): νCtO 2077 (vs), 2037 (vs), 2001 (vs), 1987
1
(vs); νCdO 1700 (s) cm-1. H NMR (400 MHz, CDCl3): 2.86 (s,
Acknowledgment. We are grateful to the National Natural
Science Foundation of China and to the Specialized Research
Fund for the Doctoral Program of Higher Education of China
for financial support of this work.
4H, 2CH2S) ppm.
X-ray Structure Determinations of A, 1, and 3-8. Single
crystals of A, 1, and 3-8 suitable for X-ray diffraction analyses
were grown by slow evaporation of the CH2Cl2/hexane solutions
of 1 and 3-5 at -10 °C, a CHCl3/hexane solution of A at -10
°C, the CH2Cl2/ petroleum ether solutions of 6 and 7 at 4 °C, or a
CH2Cl2/hexane solution of 8 at -20 °C, respectively. A single
crystal of A, 1, 6, or 7 was mounted on a Bruker SMART 1000
diffractometer. Data were collected at room temperature by using
a graphite monochromator with Mo KR radiation (λ ) 0.71073 Å)
in the ω-φꢁ scanning mode. Absorption correction was performed
by SADABS program.44 A single crystal of 3, 4, 5, or 8 was
Supporting Information Available: Full tables of crystal data,
atomic coordinates, thermal parameters, and bond lengths and angles
for A, 1, and 3-8 as CIF files. This material is available free of
charge via the Internet at http://pubs.acs.org.
IC701982Z
(45) CRYSTALCLEAR 1.3.6.; Rigaku and Rigaku/MSC: The Woodlands,
TX, 2005.
(46) Sheldrick, G. M. SHELXS97, A Program for Crystal Structure Solution;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(44) Sheldrick, G. M. SADABS, A Program for Empirical Absorption
Correction of Area Detector Data; University of Go¨ttingen: Go¨ttingen,
Germany, 1996.
(47) Sheldrick, G. M. SHELXL97, A Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
Inorganic Chemistry, Vol. 47, No. 11, 2008 4553