Formation and Reactions of Novel Types of Bridging Sulfido Anions, (μ-RE)(μ-S-)[Fe2(CO)6] 2(μ4-S) (E = S, Se): Synthesis and Structures of Double- and Triple-Butterfly Fe/E Cluster Complexes

Article abstract of DOI:10.1021/om9904753

The [Et₃NH]⁺ salts of novel anions (μ-RE)-(μ-S^-)[Fe₂(CO)₆] ₂(μ₄-S) (RE = t-BuS, P-MeC₆H₄Se) have been prepared by reaction of [(μ-RE)(μ-CO)Fe₂(CO

Full text of DOI:10.1021/om9904753

3258
Organometallics 1999, 18, 3258-3260
F or m a tion a n d Rea ction s of Novel Typ es of Br id gin g
Su lfid o An ion s, (µ-RE)(µ-S-)[F e2(CO)6]2(µ4-S) (E ) S, Se):
Syn th esis a n d Str u ctu r es of Dou ble- a n d Tr ip le-Bu tter fly
F e/E Clu ster Com p lexes
Li-Cheng Song,*,† Guo-Liang Lu,† Qing-Mei Hu,† Hong-Tao Fan,† Yu Chen,† and
J ie Sun‡
Department of Chemistry, Nankai University, Tianjin 300071, China, and Laboratory of
Organometallic Chemistry, Shanghai 200032, China
Received J une 21, 1999
Summary: The [Et3NH]+ salts of novel anions (µ-RE)-
(µ-S-)[Fe2(CO)6]2(µ4-S) (RE ) t-BuS, p-MeC6H4Se) have
been prepared by reaction of [(µ-RE)(µ-CO)Fe2(CO)6][Et3-
NH] with (µ-S2)Fe2(CO)6. While these salts react in situ
with MeI to yield the double clusters [(µ-RE)Fe2(CO)6]-
(µ4-S)[(µ-MeS)Fe2(CO)6], their reactions with SO2Cl2 in
the presence of excess [(µ-RE)(µ-CO)Fe2(CO)6][Et3NH]
afford the triple clusters [(µ-RE)Fe2(CO)6]2[(µ4-S)(Fe2-
(CO)6)2(µ4-S)].
Sch em e 1
Over the past two decades the bridging sulfido anions
(µ-S-)2Fe2(CO)6 (1) and (µ-RS)(µ-S-)Fe2(CO)6 (2), derived
from reductive cleavage of the S-S bond of the Fe/S
complex µ-S2Fe2(CO)6 (3) by corresponding nucleophiles
such as Et3BHLi,1 alkyllithium species RLi,2 and Grig-
nard reagents RMgX,3 have played an important role
in the development of the chemistry of butterfly Fe/S
cluster complexes.4 In view of our current interest in
the chemistry of butterfly Fe/E (E ) S, Se) cluster
complexes based on the complex anions [(µ-RE)(µ-CO)-
Fe2(CO)6]- (4, E ) S, Se),5 we have begun an investiga-
tion of the reaction of [Et3NH]+ salts of anions 4 with
Fe/S complex 3 to see if the S-S bond of 3 could be
cleaved by the nucleophiles of Fe-centered anions 4.
Interestingly, we found that this reaction indeed in-
volves the reductive cleavage of the S-S bond of 3,
which was presumably caused by nucleophilic attack of
the negatively charged Fe atom of 4 at the S atom of 3
to give intermediates m 1; then, m 1 might further lose
their µ-CO ligands through coordination of the µ3-S atom
to another Fe atom to give the novel bridging sulfido
anions 5, as shown in Scheme 1.
Although direct structural studies of anions 5 have
not been carried out as yet, their reactions suggest the
assigned general structure, since reactions with alkyl
halides afford products with bridging mercapto ligands,
which were fully characterized. In a typical example,
the reaction was performed with MeI as follows. A 100
mL Schlenk flask was charged with 0.504 g (1.0 mmol)
of Fe3(CO)12 and 10 mL of THF. To the resulting green
solution were added 0.11 mL (1.0 mmol) of t-BuSH and
0.14 mL (1.0 mmol) of Et3N, and the mixture was stirred
at 25-30 °C for 0.5 h to give a yellow-brown solution of
the [Et3NH]+ salt of 4 (RE ) t-BuS). To the yellow-
brown solution was added 0.344 g (1.0 mmol) of 3, and
the mixture was stirred at room temperature for 2 h to
give a brown-green solution of the [Et3NH]+ salt of 5
(RE ) t-BuS). To the brown-green solution was added
0.125 mL (2.0 mmol) of MeI, and then the mixture was
stirred for 12 h at room temperature. After removal of
the volatiles the residue was subjected to TLC. Elution
with petroleum ether gave a major red band, from which
0.668 g of 6 was obtained in 92% yield. Similarly, 7 was
obtained in 46% yield, using p-MeC6H4SeH instead of
t-BuSH and carrying out the reaction with 3 at -78 to
0 °C.
† Nankai University.
‡ Laboratory of Organometallic Chemistry.
(1) Seyferth, D.; Henderson, R. S.; Song, L.-C. J . Organomet. Chem.
1980, 192, C1.
(2) Seyferth, D.; Henderson, R. S. J . Am. Chem. Soc. 1979, 101, 508.
(3) Seyferth, D.; Henderson, R. S.; Song, L.-C.; Womack, G. B. J .
Organomet. Chem. 1985, 292, 9.
(4) For example, see: (a) Seyferth, D.; Song, L.-C.; Henderson, R.
S. J . Am. Chem. Soc. 1981, 103, 5130. (b) Seyferth, D.; Henderson, R.
S.; Song, L.-C. Organometallics 1982, 1, 125. (c) Song, L.-C.; Kadiata,
M.; Wang, J .-T.; Wang, R.-J .; Wang, H.-G. J . Organomet. Chem. 1988,
340, 239. (d) Song, L.-C.; Kadiata, M.; Wang, J .-T.; Wang, R.-J .; Wang,
H.-G. J . Organomet. Chem. 1990, 391, 387. (e) Bose, K. S.; Sinn, E.;
Averll, B. A. Organometallics 1984, 3, 1126.
(5) (a) Song, L.-C.; Yan, C.-G.; Hu, Q.-M.; Wang, R.-J .; Mak, T. C.
W. Organometallics 1995, 14, 5513. (b) Song, L.-C.; Yan, C.-G.; Hu,
Q.-M.; Wu, B.-M.; Mak, T. C. W. Organometallics 1997, 16, 632. (c)
Song, L.-C.; Yan, C.-G.; Hu, Q.-M.; Wang, R.-J .; Mak, T. C. W.; Huang,
X.-Y. Organometallics 1996, 15, 1535. (d) Song, L.-C.; Lu, G.-L.; Hu,
Q.-M.; Qin, X.-D.; Sun, C.-X.; Yang, J .; Sun, J . J . Organomet. Chem.
1998, 571, 55. (e) Song, L.-C.; Qin, X.-D.; Hu, Q.-M.; Huang, X.-Y.
Organometallics 1998, 17, 5437. (f) Song, L.-C.; Fun, H.-T.; Hu, Q.-
M.; Qin, X.-D.; Zhu, W.-F.; Chen, Y.; Sun, J . Organometallics 1998,
17, 3454.
10.1021/om9904753 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/24/1999

Communications
Organometallics, Vol. 18, No. 17, 1999 3259
F igu r e 1. ORTEP drawing of complex 7. Selected dis-
tances (Å) and angles (deg): Fe(1)-Fe(2), 2.515(2); Fe(3)-
Fe(4), 2.544(2); S(1)-Fe(1), 2.247(3); S(1)-Fe(3), 2.226(3);
Se-Fe(3), 2.391(2); Fe(1)-S(1)-Fe(2), 68.10(8); Fe(3)-
S(1)-Fe(4), 69.60(8); S(1)-Fe(1)-Fe(2), 55.92(7); S(1)-Fe-
(3)-Fe(4), 55.29(7); Fe(3)-Se-Fe(4), 64.19(5).
F igu r e 2. ORTEP drawing of complex 8. Selected dis-
tances (Å) and angles (deg): Fe(1)-Fe(2), 2.504(1); Fe(3)-
Fe(3a), 2.563(2); S(2)-Fe(1), 2.277(2); S(2)-Fe(3), 2.253(2);
Fe(1)-S(2)-Fe(2), 66.8(1); Fe(3)-S(2)-Fe(3a), 69.3(1); S(2)-
Fe(1)-Fe(2), 56.5(1); S(2)-Fe(3)-Fe(3a), 55.4(1).
of 9 was obtained if p-MeC6H4SeH was used instead of
t-BuSH.
Products 6 and 7 have been characterized by elemen-
tal and spectroscopic analyses;6 7 has been characterized
as well by X-ray diffraction analysis.7 Figure 1 repre-
sents the molecular structure of 7 with selected bond
lengths and angles. As seen in Figure 1, cluster 7 is a
chiral molecule, which consists of the two different
butterfly-shaped subcluster cores Fe(1)Fe(2)S(1)S(2) and
Fe(3)Fe(4)S(1)Se joined to a spiro type of µ4-S: i.e., the
S(1) atom. In addition, it can be seen that the two
substituents Me and p-MeC6H4 on the subclusters are
attached to S(2) and Se atoms by an equatorial bond
and each of the three CO’s attached to Fe atom is
terminal. Therefore, this structure is consistent with its
elemental and spectroscopic data and is similar to other
µ4-S and µ4-Se double clusters, such as [(µ-MeS)Fe2-
(CO)6]2(µ4-S),8 [(µ-EtS)Fe2(CO)6]2(µ4-S),4c [(µ-EtS)Fe2-
(CO)6]2(µ4-Se),5c and [(µ-p-MeC6H4Se)Fe2(CO)6]2(µ4-Se).9
Anions 5 have more interesting and useful synthetic
applications, as demonstrated by the following prepara-
tion of the novel triple butterfly cluster 8. Addition of
0.172 g (0.50 mmol) of 3 to a brown solution of ca. 1
mmol of the [Et3NH]+ salt of 4 (RE ) t-BuS) prepared
as described above resulted in formation of a brown-
green solution that was stirred at room temperature for
2 h. When this solution was cooled to -78 °C, 0.05 mL
(0.5 mmol) of SO2Cl2 was added and the solution turned
to red immediately. The mixture was warmed to room
temperature and stirred for an additional 2 h. Volatiles
were removed in vacuo, and the residue was subjected
to TLC. Petroleum ether eluted one major band, from
which 0.210 g (38%) of 8 was obtained. Similarly, 23%
Products 8 and 9 have been fully characterized by
combustion analysis and spectroscopic techniques.10 To
unambiguously confirm their structures, the X-ray
diffraction analysis for 8 was undertaken.11 Figure 2
shows the molecular structure of 8. As seen in Figure
2, 8 comprises the three butterfly-shaped Fe2S2 sub-
cluster cores Fe(1)Fe(2)S(1)S(2), Fe(3)Fe(3a)S(2)S(2a),
and Fe(1a)Fe(2a)S(1a)S(2a). It is unprecedented to have
two such µ4-S (S(2) and S(2a)) atoms. In addition, each
Fe atom has three terminal CO ligands, and the two
t-Bu groups are bonded to S(1) and S(1a) atoms by an
equatorial bond. This molecule is chiral, which has a
C2 axis passing through the two midpoints of Fe(3)-
Fe(3a) and S(2)‚‚‚S(2a). It is noteworthy that the
geometric parameters of the middle subcluster core are
somewhat different from those of the two identical side
subcluster cores. For example, the dihedral angle be-
tween Fe(3)-Fe(3a)-S(2) and Fe(3)-Fe(3a)-S(2a) (73.7°)
is less than that between Fe(1)-Fe(2)-S(1) and Fe(1)-
Fe(2)-S(2) or Fe(1a)-Fe(2a)-S(1a) and Fe(1a)-Fe(2a)-
S(2a) (86.1°), and the bond length of Fe(3)-Fe(3a)
(2.563(2) Å) is longer than that of Fe(1)-Fe(2) or Fe-
(1a)-Fe(2a) (2.504(1) Å). However, the basic geometric
parameters of this triple-butterfly cluster complex are
still comparable with those of double-butterfly
clusters.4c,5c,8,9
(6) Product 6: mp 150 °C dec; 1H NMR (CDCl3) δ 1.44 (s, 9H,
t-(CH3)3C), 2.14 (s, 3H, CH3) ppm; IR (KBr disk): 2082 (vs), 2052 (vs),
2034 (vs), 1984 (s), 1979 (s), 1972 (s), 1967 (m) cm-1. Anal. Calcd for
C17H12Fe4O12S3: C, 28.04; H, 1.65. Found: C, 28.06; H, 1.67. Product
7: mp 154 °C dec; 1H NMR (CDCl3) δ 2.17 (s, 3H, SCH3), 2.29 (s, 3H,
ArCH3), 7.12 (q, AA′BB′, J ) 7.5 Hz, 4H, C6H4); 77Se NMR (CDCl3,
Me2Se) δ 248.04 ppm; IR (KBr disk) 2082 (m), 2052 (s), 2032 (vs), 1993
(vs), 1970 (s) cm-1. Anal. Calcd for C20H10Fe4O12S2Se: C, 29.68; H, 1.24.
Found: C, 29.50; H, 1.66.
(7) X-ray data: red crystals of 7 from CH2Cl2/hexane, triclinic (P1h),
a ) 8.782(2) Å, b ) 9.093(3) Å, c ) 19.514(7) Å, R ) 86.98(2)°, â )
86.42(2)°, λ ) 68.6(2)°, Z ) 2, R ) 0.058, GOF ) 1.60.
(8) Coleman, J . M.; Wojcicki, A.; Pollick, P. J . Dahl, L. F. Inorg.
Chem. 1967, 6, 1236.
At present, we are not clear concerning the reaction
mechanism for production of 8 and 9. However, on the
(10) Product 8: mp 180 °C dec; 1H NMR (CDCl3) δ 1.48 (s, 18H,
2(CH3)3C) ppm; IR (KBr disk) 2070 (s), 2041 (vs), 1989 (vs), 1922 (s)
cm-1. Anal. Calcd for C26H18Fe6O18S4: C, 28.87; H, 1.68. Found: C,
28.84; H, 1.71. Product 9: mp 170 °C dec; 1H NMR (CDCl3) δ 2.31 (s,
6H, 2ArCH3), 7.17 (q, AA′BB′, J ) 8.3 Hz, 8H, 2C6H4); 77Se NMR
(CDCl3, Me2Se) δ 249.78 ppm; IR (KBr disk): 2085 (m), 2069 (s), 2055
(s), 2038 (vs), 2022 (s), 2006 (s), 1992 (vs) cm-1. Anal. Calcd for C32H14
Fe6O18S2Se2: C, 30.91; H, 1.14. Found: C, 30.56; H, 1.44.
-
(11) X-ray data: red crystals of 8 from CH2Cl2/hexane, monoclinic
(C2/c), a ) 27.454(5) Å, b ) 9.303(2) Å, c ) 20.136(4) Å, â ) 128.16-
(3)°, Z ) 4, R ) 0.044, S ) 0.8.
(9) Song, L.-C.; Hu, Q.-M.; Yan, C.-G.; Wang, R.-J .; Mak, T. C. W.
Acta Crystallogr. 1996, C52, 1357.

3260 Organometallics, Vol. 18, No. 17, 1999
Communications
Sch em e 2
In conclusion, we have prepared a novel type of sulfido
anions 5 through new reactions of the Fe/S complex 3
with the [Et3NH]+ salts of anions 4. Further study of
the chemical reactivities of 5 has led to the synthesis of
novel double- and triple-butterfly Fe/E (E ) S, Se)
clusters 6-9 successfully. A detailed mechanism for the
novel reaction which affords clusters 8 and 9, as well
as other interesting applications of anions 5 in the
synthesis of cluster complexes, particularly the multi-
butterfly Fe/E clusters, is under investigation.
Ack n ow led gm en t. We are grateful to the National
Natural Science Foundation of China, the State Key
Laboratory of Elemento-Organic Chemistry, and the
Laboratory of Organometallic Chemistry for financial
support.
basis of the well-known properties of both S-centered
monoanions 2 and Fe-centered monoanions 43,5c,d we
might suggest that this type of reaction would involve
the intermediates m 2 generated in situ from anions 5
and SO2Cl2. These intermediates could further react
with an excess amount of 4 via nucleophilic attack of
the negatively charged Fe atom of 4 at the bridged S
atom attached to the SO2Cl group, followed by loss of
the SO2Cl group and µ-CO ligand to give 8 and 9
(Scheme 2).
Su p p or tin g In for m a tion Ava ila ble: Text giving prepa-
ration details and characterization data for complexes 6-9 and
tables giving data collection and refinement details, atomic
coordinates, thermal parameters, and bond lengths and bond
angles of the two crystallographically characterized complexes.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM9904753