Reactions of the three-μ-CO-containing trianions {[Fe 2(μ-CO)(CO)6]3[(μ-SCH2CH2)3N]} 3-and {[Fe2(μ-CO)(CO)6]3[l,3,5- (μ-SCH2)3C6H3]}3- To give starlike complexes terminated with butterfly Fe/S cluster cores

Article abstract of DOI:10.1021/om0490280

Summary: Five starlike complexes with terminal butterfly FeIS cluster cores, [Fe2(μ-Ph₂P)(CO)6]₃[μSCH₂CH ₂N] (2), [Fe₂(μ-PhS)(CO)6]₃[(μ-SCH ₂CH₂)₃N] (3), [Fe₂(μ-PhC-NPh)(CO) ₆)]₃[1,3,5-(μ-SCH₂)3C₆H ₃ (5), and [Fe₂(μ-RSC-S)(CO)₆]3[1,3,5-(μ- SCH₂)₃ C₆H₃] (7, R = Me; 8, R = PhCH₂), were prepared by a one pot reaction of the trithiol N(CH₂CH₂SH)₃ or 1,3,5-(HSCH ₂)₃C₆H₃ with Fe₃(CO) ₁₂ and Et₃N, followed by treatment of the intermediate three-μ-CO-containing trianions {(Fe₂(μCO)(CO) ₆]₃[(μ-SCH₂CH₂) ₃N]}^3- (1) and {[Fe₂(μ-CO)(CO) ₆]₃[1,3,5-(μ-SCH₂)₃C ₆H₃]}³- (4) with Ph-PCl, PhSBr, PhC(Cl)-NPh, CSz/Mel, and CS₂PhCH₂Br, respectively. These products have been fully characterized by elemental analysis, spectroscopy, and X-ray crystallography.

Full text of DOI:10.1021/om0490280

472
Organometallics 2005, 24, 472-474
Communications
Reactions of the Three-µ-CO-Containing Trianions
{[Fe2(µ-CO)(CO)6]3[(µ-SCH2CH2)3N]}3- and
{[Fe2(µ-CO)(CO)6]3[1,3,5-(µ-SCH2)3C6H3]}3- To Give
Starlike Complexes Terminated with Butterfly Fe/S
Cluster Cores
Li-Cheng Song,* Jia Cheng, Qing-Mei Hu, Feng-Hua Gong, Hong-Zhu Bian, and
Liang-Xing Wang
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry,
Nankai University, Tianjin 300071, China
Received December 8, 2004
Scheme 1
Summary: Five starlike complexes with terminal
butterfly Fe/S cluster cores, [Fe2(µ-Ph2P)(CO)6]3[(µ-
SCH2CH2)3N] (2), [Fe2(µ-PhS)(CO)6]3[(µ-SCH2CH2)3N]
(3), [Fe2(µ-PhCdNPh)(CO)6)]3[1,3,5-(µ-SCH2)3C6H3] (5),
and [Fe2(µ-RSCdS)(CO)6]3[1,3,5-(µ-SCH2)3 C6H3] (7,
R ) Me; 8, R ) PhCH2), were prepared by a “one pot”
reaction of the trithiol N(CH2CH2SH)3 or 1,3,5-(HSCH2)3-
C6H3 with Fe3(CO)12 and Et3N, followed by treatment of
the intermediate three-µ-CO-containing trianions {[Fe2(µ-
CO)(CO)6]3[(µ-SCH2CH2)3N]}3- (1) and {[Fe2(µ-CO)-
(CO)6]3[1,3,5-(µ-SCH2)3C6H3]}3- (4) with Ph2PCl, PhSBr,
PhC(Cl)dNPh, CS2/MeI, and CS2/PhCH2Br, respective-
ly. These products have been fully characterized by ele-
mental analysis, spectroscopy, and X-ray crystallography.
Transition-metal complexes containing butterfly Fe/S
cluster cores have recently attracted increasing attention,
in view of the novelty and diversity of structures and
reactivities of such complexes1 and, particularly, the
application in bionics as models for the active site of
the iron-only hydrogenases.2-5 Previously, we reported
the type of double-butterfly Fe/S cluster dianion {[Fe2-
(µ-CO)(CO)6]2(µ-SZS-µ)}2-, a dianion that has two µ-CO
ligands capable of reaction with electrophiles to give a
series of linear and macrocyclic butterfly Fe/S cluster
complexes.6 Now, as a new development, we report two
novel triple-butterfly Fe/S cluster trianions, a type of
trianion that has three µ-CO ligands, their formation
and reactions leading to five starlike complexes termi-
nated with butterfly Fe/S cluster cores (Schemes 1 and
2).7,8
As shown in Scheme 1, reaction of the nitrogen-
containing trithiol N(CH2CH2SH)39 with Fe3(CO)12 and
Et3N in a 1:3:3 molar ratio at room temperature resulted
in formation of the [Et3NH]+ salt of the three-µ-CO-
containing trianion {[Fe2(µ-CO)(CO)6]3[(µ-SCH2CH2)3-
N]}3- (1). Further treatment of 1 in situ with excess
Ph2PCl, through triple nucleophilic attack of the three
negatively charged Fe atoms in 1 at the P atoms in three
Ph2PCl groups followed by displacement of the three
µ-CO ligands in 1, gave rise to the starlike product [Fe2-
(µ-Ph2P)(CO)6]3[(µ-SCH2CH2)3N] (2) in 32% yield. When
trianion 1 was treated with PhSBr, another starlike
complex 3 was produced in 33% yield via similar
nucleophilic attack of the three negatively charged Fe
atoms at three molecules of PhSBr followed by displace-
ment of the three µ-CO ligands.7
* To whom correspondence should be addressed. Fax: 0086-22-
23504853. E-mail: lcsong@nankai.edu.cn.
(1) For reviews, see for example: (a) Ogino, H.; Inomata, S.; Tobita,
H. Chem. Rev. 1998, 98, 2093. (b) Song, L.-C. In Trends in Organo-
metallic Chemistry; Atwood, J. L., Corriu, R., Cowley, A. H., Lappert,
M. F., Nakamura, A., Pereyre, M., Eds.; Research Trends: Trivandrum,
India, 1999; Vol. 3, p 1. (c) Song, L.-C. Acc. Chem. Res. 2005, 38, 21.
(2) (a) Li, H.; Rauchfuss, T. B. J. Am. Chem. Soc. 2002, 124, 726.
(b) Gloaguen, F.; Lawrence, J. D.; Rauchfuss, T. B. J. Am. Chem. Soc.
2001, 123, 9476. (c) Gloaguen, F.; Lawrence, J. D.; Schmidt, M.; Wilson,
S. R.; Rauchfuss, T. B. J. Am. Chem. Soc. 2001, 123, 12518.
(3) (a) Lyon, E. J.; Georgakaki, I. P.; Reibenspies, J. H.; Darens-
bourg, M. Y. J. Am. Chem. Soc. 2001, 123, 3268. (b) Darensbourg, M.
Y.; Lyon, E. J.; Zhao, X.; Georgakaki, I. P. PNAS 2003, 100, 3683.
(4) Ott, S.; Kritikos, M.; A° kermark, B.; Sun, L. Angew. Chem., Int.
Ed. 2003, 42, 3285.
(6) (a) Song, L.-C.; Fan, H.-T.; Hu, Q.-M. J. Am. Chem. Soc. 2002,
124, 4566. (b) Song, L.-C.; Fan, H.-T.; Hu, Q.-M.; Yang, Z.-Y.; Sun, Y.;
Gong, F.-H. Chem. Eur. J. 2003, 9, 170.
(5) Song, L.-C.; Yang, Z.-Y.; Bian, H.-Z.; Hu, Q.-M. Organometallics
2004, 23, 3082.
10.1021/om0490280 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 01/22/2005

Communications
Organometallics, Vol. 24, No. 4, 2005 473
Scheme 2
Similarly, Scheme 2 indicates that reaction of the
10
benzene-ring-containing trithiol 1,3,5-(HSCH2)3C6H3
Figure 1. Structure of 2 with ellipsoids drawn at the 30%
probability level. Selected bond lengths (Å) and angles
(deg): Fe(1)-Fe(2) ) 2.5550(19), Fe(1)-S(2) ) 2.268(3),
Fe(2)-S(2) ) 2.262(2), Fe(1)-P(3) ) 2.216(2), Fe(2)-P(3)
) 2.225(2), N(1)-C(1) ) 1.435(8), N(1)-C(21) ) 1.425(10);
S(2)-Fe(1)-Fe(2) ) 55.54(7), S(2)-Fe(2)-Fe(1) ) 55.78(8),
P(3)-Fe(2)-Fe(1) ) 54.73(7), P(3)-Fe(2)-S(2) ) 76.32(8),
P(3)-Fe(1)-Fe(2) ) 55.03(6), C(1)-N-C(21) ) 116.4(7).
with Fe3(CO)12 and Et3N in a 1:3:3 molar ratio afforded
the [Et3NH]+ salt of another three-µ-CO-containing
trianion, {[Fe2(µ-CO)(CO)6]3[1,3,5-(µ-SCH2)3C6H3]}3- (4).
Further treatment of 4 with excess PhC(Cl)dNPh in
situ gave the corresponding starlike product [Fe2(µ-
PhCdNPh)(CO)6]3[1,3,5-(µ-SCH2)3C6H3] (5) in 42% yield.
However, when trianion 4 was treated with excess CS2,
the S-centered trianion {[Fe2(µ-CS2)(CO)6]3 [1,3,5-(µ-
SCH2)3C6H3]}3- (6) was formed via triple nucleophilic
attack of the negatively charged Fe atoms in 4 at the C
atoms in three CS2 groups, followed by loss of the three
µ-CO ligands. Further treatment of 6 with excess MeI
or PhCH2Br yielded the final starlike products [Fe2(µ-
RSCdS)(CO)6]3[1,3,5-(µ-SCH2)3C6H3]} (7, R ) Me; 8, R
) PhCH2) in 45% and 35% yields, respectively.8
(7) 2: a mixture of Fe3(CO)12 (0.75 g, 1.5 mmol), THF (20 mL), N(CH2-
CH2SH)3 (0.065 mL, 0.5 mmol), and Et3N (0.21 mL, 1.5 mmol) was
stirred at room temperature for 1 h to give a brown-red solution
containing the [Et3NH]+ salt of trianion 1. To the solution was added
Ph2PCl (0.36 mL, 2.0 mmol), and the mixture was stirred at room
temperature for 24 h. Solvent was removed under reduced pressure.
The residue was subjected to TLC separation using acetone/petroleum
ether as eluent. From the main red band 2 was obtained as a red solid.
Yield: 0.255 g (32%). Mp: 78-80 °C. IR (KBr disk): νCtO 2059 (s),
It is worthy of note that the [Et3NH]+ salts of the
intermediate µ-CO-containing trianions 1 and 4 could
not be isolated, since they are very air-sensitive and
extremely labile during separation and purification.
However, the presence of these two trianions might be
recognized by their in situ IR spectra, which showed an
absorption band at 1742 and 1716 cm-1 typical of the
diiron-bridged µ-CO ligands.3,11 In addition, the well-
studied chemistry of the one-µ-CO-containing monoan-
ions12 and two-µ-CO-containing dianions3 and, particu-
larly, the fully characterized products 2, 3, 5, 7, and 8
by spectroscopy7,8 and X-ray crystallography13 strongly
support the formation of trianions 1 and 4.
2020 (vs), 1982 (vs) cm-1 1H NMR (CDCl3): 2.46 (t, J ) 7.0 Hz, 6H,
.
3SCH2), 2.65 (t, J ) 7.0 Hz, 6H, 3NCH2), 7.19-7.61 (m, 30H, 6C6H5);
31P NMR (121.48 MHz, CDCl3, 85% H3PO4): 142.45 (s) ppm. 3: to a
solution of trianion 1 was added PhSBr (0.375 g, 2.0 mmol). The same
workup as described above gave 3 as a red solid. Yield: 0.222 g (33%).
Mp 54-56 °C. IR (KBr disk): νCtO 2073 (s), 2036 (vs), 1995 (vs) cm-1
.
1H NMR (CDCl3): 2.28-2.82 (m, 12H, 3SCH2, 3NCH2), 7.10-7.48 (m,
15H, 3C6H5) ppm.
(8) 5: a mixture of Fe3(CO)12 (0.75 g, 1.5 mmol), THF (20 mL), 1,3,5-
(HSCH2)3C6H3 (0.114 mL, 0.5 mmol), and Et3N (0.21 mL, 1.5 mmol)
was stirred at room temperature for 1 h to give a brown-red solution
containing the [Et3NH]+ salt of trianion 4. To the solution was added
PhC(Cl)dNPh (0.641 g, 3 mmol), and the mixture was stirred at room
temperature for 24 h. Solvent was removed under reduced pressure.
The residue was subjected to TLC separation using CH2Cl2/petroleum
ether (1/2 v/v) as eluent. From the main red band 5 was obtained as a
red solid. Yield: 0.338 g (42%). Mp: 142-143 °C. IR (KBr disk): νCtO
The crystal molecular structures of 2 and 7 are
presented in Figures 1 and 2, respectively. As can be
seen in Figure 1, complex 2 contains three identical
Fe2SP butterfly cluster cores, in which each of the P
atoms is attached to two phenyl groups and each of the
2066 (s), 2027 (vs), 1987 (vs) cm-1 1H NMR (CDCl3): 3.64 (s, 6H,
.
3SCH2), 6.48-7.51 (m, 33H, C6H3, 6C6H5) ppm. 7: the solution
containing the [Et3NH]+ salt of trianion 4 prepared above was cooled
to -40 °C. To this solution was added CS2 (0.18 mL, 3.0 mmol). After
the mixture was stirred at this temperature for 1 h, MeI (0.19 mL, 3
mmol) was then added. The new mixture was stirred at room
temperature for 24 h. Using the same workup as described above, 7
was obtained as a red solid. Yield: 0.297 g (45%). Mp: 56-58 °C. IR
(11) Seyferth, D.; Womack, G. B.; Dewan, J. C. Organometallics
1985, 4, 398.
(12) (a) Seyferth, D.; Womack, G. B.; Archer, C. M.; Dewan, J. C.
Organometallics 1989, 8, 430. (b) Seyferth, D.; Hoke, J. B.; Womack,
G. B. Organometallics 1990, 9, 2662. (c) Song, L.-C.; Lu, G.-L.; Hu,
Q.-M.; Sun, J. Organometallics 1999, 18, 2700. (d) Song, L.-C.; Lu, G.-
L.; Hu, Q.-M.; Fan, H.-T.; Chen, Y.; Sun, J. Organometallics 1999, 18,
3258.
(KBr disk): νCtO 2066 (s), 2028 (vs), 1993 (vs); νCdS 1017 (s) cm-1 1H
.
NMR (CDCl3): 2.53 (s, 9H, 3CH3), 3.77 (s, 6H, 3SCH2), 7.20-7.40 (m,
3H, C6H3) ppm. 8: similarly, when PhCH2Br (0.36 mL, 3.0 mmol) was
used instead of MeI, 8 was obtained as a red solid. Yield: 0.271 g (35%).
Mp: 60-62 °C. IR (KBr disk): νCtO 2066 (s), 2028 (vs), 1993 (vs); νCdS
(13) X-ray crystal data are as follows. 2: C60H42Fe6NO18P3S3,
orthorhombic, Pna21, a ) 18.1190(7) Å, b ) 14.9011(6) Å, c ) 25.4867-
(10) Å, R ) â ) γ ) 90 °, F(000) ) 3208, V ) 6881.2(5) Å3, Dc ) 1.534
g cm-3, µ(Mo KR) ) 1.458 mm-1, R ) 0.0468, Rw ) 0.0840, GOF )
1.000. 7:C33H18Fe6O18S9‚0.25CH2Cl2, triclinic, P1h, a ) 13.612(5) Å, b
) 14.753(6) Å, c ) 15.879(6) Å, R ) 64.381(7) °, â ) 70.868(7)°, γ )
81.534(8)°, F(000) ) 1341, V ) 2716.4(18) Å3, Dc ) 1.647 g cm-3, µ(Mo
KR) ) 1.991 mm-1, R ) 0.0811, Rw ) 0.2065, GOF ) 1.015.
1016 (s) cm-1 1H NMR (CDCl3): 3.78 (s, 6H, 3SCH2), 4.26 (s, 6H,
.
3SCH2Ph), 7.12-7.45 (m, 18 H, C6H3, 3C6H5) ppm.
(9) Harley-Mason, J. J. Chem. Soc. 1947, 320.
(10) Houk, J.; Whitesides, G. M. J. Am. Chem. Soc. 1987, 109, 6825.

474 Organometallics, Vol. 24, No. 4, 2005
Communications
butterfly Fe2S2C cluster cores of 7, for example, the
double bond C(28)dS(4), is extended to 1.654(12) Å due
to its coordination in comparison with the CdS double
bond in free CS2 (1.554 Å),15 but it is still shorter than
its single bonds C(28)-S(5) (1.695(10) Å), S(5)-C(29),
(1.818(11) Å) and S(1)-C(25) (1.826(9) Å). The double
bond C(28)dS(4) is bridged to Fe(1) via a σ bond (Fe(1)-
C(28) ) 1.988(10) Å) and to Fe(2) via the donation of
an unshared electron pair from S(4) (Fe(2)-S(4) )
2.276(3) Å). In fact, such a coordination mode of the CdS
double bonds in 7 has been found in other µ-CS2
complexes.6,16 In addition, as can be seen in Figure 2,
the three identical cluster cores in 7 are joined together
by connecting their S atoms with three benzylic C atoms
of the planar trimethylene benzene ring structural
moiety also via three equatorial bonds.14
In summary, we have synthesized and structurally
characterized five starlike complexes, namely 2, 3, 5,
7, and 8, each containing three terminal butterfly Fe2S2
or Fe2S2C cluster cores radiating from a pyramidal N
atom or a planar benzene ring. The “one pot” reactions
for synthesizing such starlike complexes involve two
new intermediates of the three-µ-CO-containing trian-
ions 1 and 4 that were generated from Fe3(CO)12, Et3N,
and the trithiol N(CH2CH2SH)3 or 1,3,5-(HSCH2)C6H3.
In view of the easy availability of trianions 1 and 4, as
well as their high nucleophilicity, they could become an
important class of building blocks in transition-metal
chemistry. Investigations to make new trianions by
using other trithiols and to synthesize new starlike
complexes terminated with other Fe/S cluster cores are
underway in this laboratory.
Figure 2. Structure of 7 with ellipsoids drawn at 30%
probability. Selected bond lengths (Å) and angles (deg):
Fe(1)-Fe(2) ) 2.618(2), Fe(1)-S(1) ) 2.265(3), Fe(2)-S(4)
) 2.276(3), Fe(1)-C(28) ) 1.988(10), Fe(2)-S(1) ) 2.253(3),
S(1)-C(25) ) 1.826(9); S(1)-Fe(1)-Fe(2) ) 54.36(8), S(1)-
Fe(2)-S(4) ) 82.41(12), Fe(2)-S(1)-Fe(1) ) 70.83(9), S(1)-
Fe(2)-Fe(1) ) 54.80(8), C(28)-Fe(1)-S(1) ) 81.4(4), S(4)-
Fe(2)-Fe(1) ) 77.89(10).
Fe atoms is attached to three terminal CO ligands.
Therefore, this is consistent with their 31P NMR and
IR spectra, which displayed respectively one singlet at
142.45 ppm and several absorption bands at ca. 2000
cm-1. Also, it can be seen that the three butterfly Fe2SP
cluster cores in 2 are connected through their S atoms
to three â-C atoms of the triethyleneamine structural
unit by three equatorial bonds. In fact, this is necessary
to avoid the strong axial-axial repulsions between the
axially bonded bulky phenyl groups at P atoms and the
central part of this complex.14
Acknowledgment. We are grateful to the National
Natural Science Foundation of China and the State Key
Laboratory of Organometallic Chemistry for financial
support of this work.
Supporting Information Available: X-ray crystallo-
graphic files for 2 and 7 in CIF format and text giving details
of the synthesis and characterization of 2, 3, 5, 7, and 8. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Figure 2 shows that 7 has another three identical
butterfly Fe2S2C cluster cores, in which the C atom is
bound to the methylthio group and each of the Fe atoms
is bonded to three terminal carbonyls, consistent with
OM0490280
(14) (a) Shaver, A.; Fitzpatrick, P. J.; Steliou, K.; Butler, I. S. J.
Am. Chem. Soc. 1979, 101, 1313. (b) Seyferth, D.; Henderson, R. S.;
Song, L.-C. Organometallics 1982, 1, 125.
(15) Butler, I. S.; Fenster, A. E. J. Organomet. Chem. 1974, 66, 161.
(16) Patin, H.; Mignani, G.; Mahe´, C.; Le Marouille, J.-Y.; Southern,
T. G.; Benoit, A. J. Organomet. Chem. 1980, 197, 315.
1
its H NMR and IR spectra displaying one singlet at
2.53 ppm and several absorption bands at ca. 2000 cm-1
.
It is noteworthy that the CdS double bonds in the