Synthesis and structural characterization of diiron ethanedithiolate complex [(μ-SCH2)2Fe2(CO)4](PPh3)2related to the active site of [Fe-Fe]-hydrogenases

Article abstract of DOI:10.14233/ajchem.2014.16763

A diiron ethanedithiolate complex [(μ-SCH₂)₂Fe₂(CO)₄](PPh₃)₂(1), as the active site of [Fe-Fe]-hydrogenases, has been prepared and characterized. The title complex was prepared by reaction of [(μ-SCH₂)₂]Fe₂(CO)₆( A) with PPh3 at reflux in xylene in 50% yield. The new complex was characterized by IR, ¹H NMR, ³¹P NMR and ¹³C NMR spectroscopy.

Full text of DOI:10.14233/ajchem.2014.16763

Asian Journal of Chemistry; Vol. 26, No. 19 (2014), 6687-6688
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.16763
NOTE
Synthesis and Structural Characterization of Diiron Ethanedithiolate Complex
2 2
[(µ-SCH ) Fe
2
(CO) ](PPh
4
3
)
2
Related to the Active Site of [Fe-Fe]-Hydrogenases
*
WEI GAO, TING-TING ZHANG and YAN-JUN SUN
School of Pharmacy, Henan University of Traditional Chinese Medicine, Zhengzhou 450046, P.R. China
Corresponding author: E-mail: weigao415@aliyun.com
*
Received: 26 November 2013;
Accepted: 14 January 2014;
Published online: 16 September 2014;
AJC-15989
A diiron ethanedithiolate complex [(µ-SCH
characterized. The title complex was prepared by reaction of [(µ-SCH
2
)
2
Fe
2
(CO)
4
](PPh
3
)
2
(1), as the active site of [Fe-Fe]-hydrogenases, has been prepared and
]Fe (CO) (A) with PPh at reflux in xylene in 50 % yield. The
2
)
2
2
6
3
1
new complex was characterized by IR, H NMR, P NMR and C NMR spectroscopy.
31
13
Keywords: Diiron ethanedithiolate, Triphenylphosphine, Synthesis, Characterization.
3
1
In recent years, butterfly [2Fe-2S] have received special
attention due to their unique structure and close relationship
(2s, 30 H, Ar-H), 1.57, 1.28 (2s, 4H, 2SCH
(200 MHz, CDCl , 85 % H PO ): 60.03 (s) ppm. C NMR
(125 MHz, CDCl ): 216.78, 216.74 (C≡O), 136.93, 136.64,
133.21, 133.16, 133.12, 129.59, 128.34, 128.31 (Ar-C), 32.83
(CH ) ppm.
As shown in Scheme-I, treatment of complex A with 2
equivalent of PPh at reflux in xylene afforded the title complex
1 in 50 % yield. The title complex 1 was air-stable red solids,
2
) ppm. P NMR
13
3
3
4
1
with the natural enzymes of [Fe-Fe]-hydrogenases . Protein
3
crystallographic studies revealed that the active site of [Fe-Fe]-
hydrogenases consists of a butterfly [2Fe-2S] cluster linked
to a cubane-like [4Fe-4S] cluster via the sulfur atom of a cysteinyl
2
2
group . Based on structural information, a good number of
3
3
diiron dithiolate complexes were prepared and structurally
-5
6
characterized by various techniques in order to mimic the
1
31
which has been characterized by IR, H NMR, P NMR and
C NMR spectroscopy.
1
3
natural properties of [Fe-Fe]-hydrogenases. In this paper, we
report the synthesis and structural characterization of diiron
ethanedithiolate complex related to the active site of [Fe-Fe]-
hydrogenases.
S
S
PPh3
S
S
CO
Reaction and operation was carried out under a dry, oxygen
free nitrogen atmosphere with standard Schlenk and vacuum
line techniques. Acetonitrile was distilled with CaH
OC
PPh3
CO
Ph P
3
Fe
Fe
xylene
OC
OC
CO
CO
Fe
Fe
OC
2
under
OC
CO
N
2
.Me NO·2H O, PPh and other materials were commercially
3
2
3
A
1
available and used as received. Complex A was prepared accor-
7
ding to the literature procedures . IR spectra were recorded
Scheme-1: Synthesis of the title complex 1
1
31 13
on a Nicolet 670 FTIR spectrometer. H ( P, C) NMR spectra
were obtained on a Bruker Avance 500 MHz spectrometer.
Infrared spectrum:As shown in Fig. 1, the IR spectrum
of 1 displayed two strong absorption bands at 1993 and 1933
2 2 2 6
Synthesis:A mixture of (µ-SCH ) Fe (CO) (0.186 g, 0.5
3
mmol), PPh (0.262 g, 1 mmol) and xylene (20 mL) was
-
1
cm for the terminal carbonyls and the ν(C≡O) values of
complex 1 are shifted toward lower frequencies relative to the
refluxed for 4 h to give a brown-red solution. The solvent was
reduced in vacuo and the residue was subjected to TLC
-1 7
parent complex A (2079, 2039, 2009, 1996 cm ) because PPh
3
is stronger electron donating than CO.
1
separation using CH
Collecting the main red band afforded 0.201 g (48 %) of 1 as
a red solid. Anal. Calcd. for C42 Fe : C, 60.02; H,
.08. Found: C, 60.31; H, 4.24. IR (KBr, νmax, cm ): C≡O
2 2
Cl /petroleum ether (v/v = 1:1) as eluent.
1
H NMR spectrum: As shown in Fig. 2, the H NMR
spectrum of 1 showed two singlets at δ 7.58 and 7.39 ppm for
its phenyl protons and two singlets at δ 1.57 and 1.28 ppm for
the methylene protons.
34 4 2
H O P S
2
2
-1
4
1
1
3
994 (vs), 1932 (vs). H NMR (500 MHz, CDCl ): 7.58, 7.39

6
688 Gao et al.
Asian J. Chem.
13
13
C NMR spectrum. As shown in Fig. 4, the C NMR
spectrum of 1 demonstrated a doublet at δ 216.76 ppm for the
terminal carbonyls and a singlet at δ 32.83 ppm for the meth-
ylene carbons.
100
8
0
3
500
3000
2500
2000
1500
1000
500
-1
Wavenumber (cm
)
Fig. 1. IR spectrum of the title complex 1
200
150
100
50
13
Fig. 4. C NMR spectrum of the title complex 1
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the financial support
by the National Natural Science Foundation of China (31300284).
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00
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31
Fig. 3. P NMR spectrum of the title complex 1