Synthetic and structural investigations on some new 1,2,4,5-(CH 2)4C6H2 moiety-containing butterfly Fe/S cluster complexes from reactions of tetrathiol 1,2,4,5-(HSCH 2)4C6H2

Article abstract of DOI:10.1021/om300395z

The 1,2,4,5-(CH₂)₄C₆H₂ moiety-containing butterfly Fe/S complexes [1,2-(CH₂S ₂CH₂)-4,5-(μ-SCH₂)₂C ₆H₂][Fe₂(CO)₆]

Full text of DOI:10.1021/om300395z

Article
pubs.acs.org/Organometallics
Synthetic and Structural Investigations on Some New 1,2,4,5-
(CH2)4C6H2 Moiety-Containing Butterfly Fe/S Cluster Complexes from
Reactions of Tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 or with
Fe3(CO)12 in the Presence of Et3N
Li-Cheng Song,* Chun-Hui Qi, Hai-Lin Bao, Xiao-Niu Fang,† and Hai-Bin Song
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
S
* Supporting Information
ABSTRACT: The 1,2,4,5-(CH2)4C6H2 moiety-containing
butterfly Fe/S complexes [1,2-(CH2S2CH2)-4,5-(μ-
SCH2)2C6H2][Fe2(CO)6] (1), [1,2,4,5-(μ-SCH2)4C6H2]-
[Fe2(CO)6]2 (2), and [(1,2-Me2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)6] (3) have been prepared by the reaction of
tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 under
different conditions. Treatment of complex 1 with PPh3 or
PMe3 in the presence of Me3NO or with the in situ generated
N-heterocyclic carbene IMes (IMes = 1,3-bis(mesityl)imidazol-2-
ylidene) afforded the corresponding monosubstituted single-
butterfly complexes [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)5L] (4, L = PPh3; 5, L = PMe3; 6, L = IMes).
However, in contrast to the above-mentioned reaction of
tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12, the reac-
tions of 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 in the
presence of Et3N, followed by treatment with PhCOCl or
PhC(Cl)NPh, resulted in formation of the quadruple- and
triple-butterfly complexes [(μ-PhCO)Fe2(CO)6]4[1,2,4,5-
(μ-SCH2)4C6H2] (7) and [(μ-PhCNPh)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (8), whereas the same tetrathiol
reaction system reacted with PhCCH to give quadruple- and triple-butterfly complexes [(μ-σ,π-PhCHCH)-
Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (9) and [(μ-σ,π-PhCHCH)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (10).
More interestingly, the dithioformato ligand-containing quadruple-butterfly complex [(μ-SCSCH2Ph)Fe2(CO)6]4[1,2,4,5-
(μ-SCH2)4C6H2] (11) could be prepared by the reaction of the tetrathiol system with CS2, followed by treatment with PhCH2Br,
but the same tetrathiol/CS2 system reacted with CpFe(CO)2I to afford the triple-butterfly complex [(μ-SCSFe(CO)2Cp)-
Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (12). The possible pathways for production of complexes 1−3 and 7−12 are
proposed, and the suggested intermediate [1,2-(HSCH2)2-4,5-(μ-SCH2)2C6H2][Fe2(CO)6] (M6) for formation of complex 1 has
been successfully isolated under anaerobic conditions. The structures of complexes 1, 3, 4, 8, 9, and 11 have been confirmed by
X-ray crystallography.
recently launched a comparative study of the direct reaction of
tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 and the
sequential reactions of the same tetrathiol with Fe3(CO)12 in
the presence of Et3N, followed by treatment with electrophiles.
Interestingly, through such a study, we have expanded the
applied scope of the aforementioned two synthetic methods
and thus prepared some new types of 1,2,4,5-(SCH2)4C6H2
moiety-containing butterfly Fe/S cluster complexes. Herein, we
report these interesting results from this study.
INTRODUCTION
■
Butterfly Fe/S cluster complexes have attracted growing
interest during recent years, presumably owing to their rich
chemistry1−5 and particularly their close relationships with the
active site of [FeFe]-hydrogenases.6−10 Since 1928, when
Reihlen prepared the first dinuclear butterfly Fe/S cluster
complex (μ-EtS)2Fe2(CO)6,11 a great number of butterfly Fe/S
cluster complexes have been prepared by various synthetic
methods, such as the old method involving reactions of various
thiols with iron(0) carbonyls12−15 and the new method
involving reactions of various thiols with Fe3(CO)12 and
Et3N, followed by treatment with electrophiles.16−21 To
develop the organometallic synthetic methodology and to
prepare the new type of butterfly Fe/S cluster complexes, we
Received: May 10, 2012
Published: July 17, 2012
© 2012 American Chemical Society
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Scheme 1
M4 and tetrairon intermediate M5 are produced by loss of the
corresponding H atoms, S atoms, and CO ligands from
intermediates M1 and M2. The intramolecular coordination/
cyclization of M3, M4, and M5 affords dithiol intermediate M6
and products 3 and 2, and the oxidation of the dithiol
intermediate M6 by air results in formation of product 1.
It is worth noting that, although some details regarding this
parthway need to be further studied, it appears to be plausible.
This is because (i) the thermal reactions of Fe3(CO)12 with
thiols to give the butterfly (μ-S)2Fe2(CO)6 cluster-unit-
containing complexes accompanied by evolution of H2 and
CO gases are precedented,13,24 (ii) the suggested dithiol
intermediate M6 could be isolated in an anaerobic glovebox by
TLC and was characterized by elemental analysis and
spectroscopy, and (iii) when a toluene solution of the isolated
M6 was heated at about 90 °C for 10 min in air, 1 was obtained
in 71% yield.
RESULTS AND DISCUSSION
■
Reaction of Tetrathiol 1,2,4,5-(HSCH2)4C6H2 with
Fe3(CO)12. Synthesis and Characterization of Single-
and Double-Butterfly Complexes [1,2-(CH2S2CH2)-4,5-(μ-
SCH2)2C6H2][Fe2(CO)6] (1), [1,2,4,5-(μ-SCH2)4C6H2]
[Fe2(CO)6]2 (2), and [(1,2-Me2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)6] (3). Although the direct reactions of mono-, di-,
and trithiols with Fe3(CO)12 are known to give the
corresponding butterfly Fe/S cluster complexes,12−15,22,23 no
report has so far appeared in the literature regarding the direct
reaction of tetrathiol with Fe3(CO)12. However, we found that
simple treatment of tetrathiol 1,2,4,5-(HSCH2)4C6H2 with
Fe3(CO)12 in a 1:1 molar ratio in refluxing THF, after the
open-air TLC separation, gave rise to the S−S bond-containing
single-butterfly Fe/S cluster complex 1 in 20% yield, whereas
the same tetrathiol reacted with Fe3(CO)12 in a 1:2 molar ratio
under the same conditions and through the same separation
procedure to give not only the single-butterfly Fe/S complex 1
in 8% yield but also a double-butterfly Fe/S complex 2 in 18%
yield, respectively (Scheme 1).
Complexes 1−3 are air-stable red solids, which have been
characterized by elemental analysis and spectroscopy. For
example, the IR spectra of 1−3 showed three absorption bands
in the range of 2073−1985 cm−1 for their terminal carbonyls.
Similarly, it was further found that the reaction of 1,2,4,5-
(HSCH2)4C6H2 with Fe3(CO)12 in a 1:1 molar ratio in toluene
at 90 °C also afforded single-butterfly complex 1 in a nearly
identical yield (19%), whereas the tetrathiol reacted with
Fe3(CO)12 in a 1:2 molar ratio under the same conditions to
give the double-butterfly complex 2 in 22% yield and another
type of single-butterfly Fe/S complex 3 in 5% yield (Scheme 2).
1
The H NMR spectra of 1−3 displayed a singlet at ca. 6.85
ppm for the two protons bound to their benzene rings, whereas
1 and 3 exhibited two doublets at ca. 3.09 and 3.80 ppm for the
two methylene groups attached to their single-butterfly Fe/S
cluster cores and 2 showed two multiplets in the range of 2.91−
3.82 ppm for the four methylene groups attached to the
double-butterfly cluster core, indicative of the different
influences of the two single-butterfly cluster moieties in 2. In
addition, the 13C NMR spectra of 1−3 showed one or two
singlets in the range of 207−209 ppm for their terminal
carbonyls.
Scheme 2
Fortunately, the structures of 1 and 3 were confirmed by X-
ray crystallography. The molecular structures of 1 and 3 are
shown in Figures 1 and 2, whereas their selected bond lengths
and angles are presented in Table 1. As can be seen in Figures 1
and 2, complexes 1 and 3 are structurally very similar; both of
them contain a butterfly cluster unit (μ-S)2Fe2(CO)6 that is
connected via its two sulfur atoms (namely, S1 and S2) to the
two neighboring α-carbon atoms (namely, C7/C16 for 1 and
C7/C14 for 3) of the corresponding benzene ring. However,
they do have some differences. That is, while the two
neighboring α-carbon atoms of the benzene ring in 3 (namely,
C10/C11) are connected to two methyl groups, the
corresponding two α-carbon atoms in 1 (namely, C11/C12)
are linked to S3 and S4 atoms to construct a chair-shaped
C10C11S4S3C12C13 six-membered ring. It is noteworthy that
the single bond length S3−S4 in complex 1 is 2.0294 Å, which
It follows that the types and yields of the products obtained
from such direct reactions can be considerably influenced by
the molar ratio of the starting materials and the reaction
temperature in different solvents.
A possible pathway for formation of complexes 1−3 is shown
in Scheme 3. That is, in the first step, the unsaturated 16e
species Fe(CO)4 is generated by thermal decomposition of
Fe3(CO)12. Addition of two or four Fe(CO)4 species to the
tetrathiol then affords the coordinatively saturated diiron
intermediate M1 and tetrairon intermediate M2. In the third
step, the coordinatively unsaturated diiron intermediates M3/
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Scheme 3
Figure 1. Molecular structure of 1 with 30% probability level
ellipsoids.
Figure 2. Molecular structure of 3 with 30% probability level
ellipsoids.
is almost the same as the S−S bond length (2.01 Å) in
tetrahedral cluster (μ-S2)Fe2(CO)6.25
Reactions of Single-Butterfly Complex 1 with PPh3,
PMe3, and IMes. Synthesis and Characterization of [1,2-
(CH2S2CH2)-4,5-(μ-SCH2)2C6H2][ Fe2(CO)5L] (4, L = PPh3; 5,
L = PMe3; 6, L = IMes). The substituted derivatives of single-
butterfly complex 1 were found to be prepared by CO
substitution reactions. For instance, while 1 reacted with PPh3
or PMe3 in the presence of decarbonylating agent Me3NO to
give the PPh3- and PMe3-monosubstituted complexes 4 and 5
in ca. 29% yields, treatment of 1 with the N-heterocyclic
carbene IMes (IMes = 1,3-bis(mesityl)imdazol-2-ylidene) gen-
erated in situ from imidazolium salt IMes·HCl and n-BuLi in
THF at room temperature gave the IMes-monosubstituted
complex 6 in 22% yield (Scheme 4).
Complexes 4−6 are also air-stable red solids, which have
1
been characterized by elemental analysis and IR and H (13C)
NMR spectroscopy. For example, the IR spectra of 4−6
showed three to four absorption bands in the region of 2044−
1914 cm−1 for their terminal carbonyls. It follows that the νCO
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Table 1. Selected Bond Lengths (Å) and Angles (deg) for 1 and 3
compound 1
Fe(1)−S(2)
Fe(2)−S(2)
S(3)−S(4)
S(1)−C(7)
2.2461(9)
2.2511(11)
2.0294(11)
1.842(2)
Fe(1)−S(1)
Fe(1)−Fe(2)
Fe(2)−S(1)
S(2)−C(16)
2.2491(11)
2.5101(10)
2.2494(8)
1.833(2)
Fe(1)−C(1)
1.805(2)
Fe(2)−C(6)
1.787(3)
C(7)−S(1)−Fe(1)
S(1)−Fe(2)−S(2)
S(1)−Fe(2)−Fe(1)
Fe(1)−S(2)−Fe(2)
C(12)−S(3)−S(4)
117.49(8)
87.25(3)
C(7)−S(1)−Fe(2)
S(2)−Fe(2)−Fe(1)
S(2)−Fe(1)−S(1)
Fe(1)−S(1)−Fe(2)
C(11)−S(4)−S(3)
112.76(8)
55.98(4)
56.08(3)
87.38(4)
67.86(3)
67.83(3)
96.47(9)
99.21(8)
compound 3
Fe(1)−C(1)
Fe(1)−S(2)
Fe(2)−S(2)
Fe(1)−Fe(2)
1.815(2)
2.2594(18)
2.2699(18)
2.5139(16)
1.852(2)
Fe(2)−C(6)
Fe(1)−S(1)
Fe(2)−S(1)
S(2)−C(14)
1.803(2)
2.2686(18)
2.2516(13)
1.851(2)
1.491(3)
114.69(6)
87.08(3)
55.89(2)
56.09(4)
67.43(3)
S(1)−C(7)
C(7)−C(8)
C(7)−S(1)−Fe(1)
S(1)−Fe(2)−S(2)
S(2)−Fe(1)−Fe(2)
S(1)−Fe(2)−Fe(1)
Fe(2)−S(1)−Fe(1)
115.50(7)
87.23(5)
C(14)−S(2)−Fe(1)
S(2)−Fe(1)−S(1)
S(1)−Fe(1)−Fe(2)
S(2)−Fe(2)−Fe(1)
Fe(1)−S(2)−Fe(2)
56.48(6)
56.53(5)
67.58(5)
ligand PPh3 is located at the apical position of the square-
pyramidal iron atom and trans to its (1,2-CH2S2CH2)C6H2
moiety in order to avoid the strong steric repulsion between
them. In addition, the S3−S4 bond length (2.0370 Å) in 4 is
slightly longer than that in its parent complex 1, which is very
close to those S−S single bond lengths of 2.01 Å in (μ-
Scheme 4
25
S)2Fe2(CO)6 and 2.04 Å in S2Cl2 and S8.26,27 The Fe1−Fe2
bond length (2.5106 Å) and the Fe1−P1 bond length (2.2512
Å) are close to the corresponding bond lengths in similar
monophosphine-substituted Fe/S cluster complexes.28−31
Reactions of Tetrathiol System 1,2,4,5-(HSCH2)4C6H2/
Fe3(CO)12/Et3N with PhCOCl, Ph(Cl)CNPh, and PhC
CH. Synthesis and Characterization of Quadruple- and
T r i p l e - B u t t e r fl y C o m p l e x e s [ ( μ - P h C  O ) -
Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (7), [(μ-PhCNPh)-
Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (8), [(μ-σ,π-
PhCHCH)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (9), and
[(μ-σ,π-PhCHCH)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-
SCH2)4C6H2] (10). We previously reported that reaction of
tetrathiol 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 and Et3N in
a 1:4:4 molar ratio in THF at room temperature afforded the
[Et3NH]4 salt of tetraanion {[(μ-CO)Fe2(CO)6]4[1,2,4,5-(μ-
SCH2)4C6H2]}4− (A) and the [Et3NH]2 salt of dianion {[(μ-
CO)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2]}2− (B),
which were reacted in situ with electrophiles 2-furancarbonyl
chloride and Ph2PCl to give the corresponding furan ring-
containing quadruple-butterfly and Ph2P ligand-containing
triple-butterfly complexes (Scheme 5).21
To develop this new method for synthesis of the other new
types of butterfly Fe/S cluster complexes, we continued to
study the in situ reactions of such a tetrathiol system with
electrophiles PhCOCl, PhC(Cl)NPh, and PhCCH.
Interestingly, it was found that this tetrathiol system could
react in situ with PhCOCl under similar conditions to produce
quadruple-butterfly complex [(μ-PhCO)Fe2(CO)6]4[1,2,4,5-
(μ-SCH2)4C6H2] (7) in 22% yield, whereas it reacted with
PhC(Cl)NPh to afford triple-butterfly complex [(μ-PhC
NPh)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (8) in
frequencies of 4−6, relative to those of their parent complex 1,
are shifted toward lower frequencies by 28−76 cm−1, which is
consistent with PPh3, PMe3, and the NHC ligand IMes being
1
stronger σ-donors than terminal carbonyls. In the H NMR
spectra, complex 4 showed a singlet at 6.62 ppm for the two
protons attached to its benzene ring, 5 displayed a doublet at
1.43 ppm for the nine protons of the three methyl groups
attached to its P atom, and 6 exibited a singlet at 7.13 ppm for
the two imidazole protons in its IMes ligand. In the 13C NMR
spectra, complex 4 showed two singlets at 208.3 and 212.5 ppm
for its terminal carbonyl C atoms, 5 displayed a doublet at 19.7
ppm for the carbon atoms of its three methyl groups attached
to the P atom, and 6 exhibited a singlet at 195.6 ppm for its
carbene C atom. In addition, the 31P NMR spectra of 4 and 5
displayed a singlet at 64.53 and 26.26 ppm, respectively.
The molecular structure of complex 4 has been unequivocally
confirmed by X-ray crystallography. While its ORTEP drawing
is depicted in Figure 3, Table 2 presents the selected bond
lengths and angles. As shown in Figure 3, the monophosphine
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Figure 3. Molecular structure of 4 with 30% probability level ellipsoids.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 4
Fe(1)−S(2)
Fe(1)−P(1)
Fe(2)−S(2)
S(1)−C(24)
2.2876(15)
2.2512(16)
2.2906(14)
1.859(4)
Fe(1)−S(1)
Fe(1)−Fe(2)
Fe(2)−S(1)
S(2)−C(33)
2.2846(14)
2.5106(14)
2.2679(15)
1.845(4)
P(1)−C(6)
1.842(4)
S(3)−S(4)
2.0370(19)
104.26(5)
155.07(5)
56.80(4)
P(1)−Fe(1)−S(1)
S(1)−Fe(1)−S(2)
S(1)−Fe(1)−Fe(2)
S(1)−Fe(2)−S(2)
Fe(1)−S(2)−Fe(2)
110.94(5)
86.22(5)
P(1)−Fe(1)−S(2)
P(1)−Fe(1)−Fe(2)
S(2)−Fe(1)−Fe(2)
Fe(2)−S(1)−Fe(1)
C(28)−S(3)−S(4)
56.22(4)
86.54(5)
66.94(5)
66.51(5)
97.23(14)
Scheme 5
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Scheme 6
Scheme 7
18% yield (Scheme 6). Apparently, the formation of complex 7
is most likely via the nucleophilic attack of the four negatively
charged Fe atoms in A at the leaving group (Cl−)-attached C
atoms in four molecules of PhCOCl, followed by displacement
of the four μ-CO ligands in A and by subsequent intramolecular
O atom coordination of the four PhCO ligands.16,19 Similarly,
the nucleophilic attack of the two negatively charged Fe atoms
in B at the leaving group (Cl−)-attached C atoms in two
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molecules of PhC(Cl)NPh, followed by displacement of the
two μ-CO ligands in B by intramolecular N atom coordination
of the two PhCNPh ligands, resulted in formation of triple-
butterfly complex 8.32−34
Particularly interesting is that, in contrast to the afore-
mentioned electrophiles with a leaving group, the electrophile
PhCCH without a leaving group was found to react with the
[Et3NH]4 salt of tetraanion A and the [Et3NH]2 salt of dianion
B to give both quadruple- and triple-butterfly complexes [(μ-
σ,π-PhCHCH)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (9) and
[(μ-σ,π-PhCHCH)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-
SCH2)4C6H2] (10) in 12% and 25% yields, respectively
(Scheme 7). Complex 9 might be produced by nucleophilic
attack of the four negatively charged Fe atoms in A at β-C
atoms of four phenyl acetylene molecules (both steric
considerations and the ability of the phenyl group to stabilize
α-carbanions favor β attack of the iron centered nucleophile),
followed by loss of four μ-CO ligands from the initially formed
[Et3NH]4 salt of the C-centered tetraanion and subsequent
intramolecular protonation by its [Et3NH]4 cations. In
addition, the nucleophilic attack of the negatively charged Fe
atoms in the [Et3NH]2 salt of dianion B at β-C atoms of
phenylacetylene molecules, followed by loss of its two μ-CO
ligands and subsequent intramolecular protonation of the
corresponding C-centered dianion, resulted in formation of
triple-butterfly complex 10.35
Figure 4. Molecular structure of 8 with 30% probability level
ellipsoids.
Fe2(CO)6(μ-S)]4, which are connected through their μ-S
atoms to each α-C atom of the central benzene ring by an
equatorial type of bond2,39 (the angle C21−S1····C13 = 149.2°,
and the angle C25−S2····C26 = 152.4°). It is noteworthy that
the C−C bond lengths of the bridging substituted vinyl ligands
(C13−C14 = 1.360 Å, C26−C27 = 1.391 Å) are obviously
longer than the normal value for a CC double bond, which
demonstrates that the CC double bond in each of the
bridging substituted vinyl ligands is coordinated to the two iron
atoms in a σ, π manner (Fe1−C13 σ-bond length is 1.974 Å;
Fe2−C13 and Fe2−C14 π-bond lengths are 2.066 and 2.266 Å,
respectively; Fe3−C26 σ-bond length is 1.975 Å; Fe4−C26 and
Fe4−C27 π-bond lengths are 2.086 and 2.232 Å, respec-
tively).35,37
Reactions of Tetrathiol System 1,2,4,5-(HSCH2)4-C6H2/
Fe3(CO)12/Et3N with CS2, Followed by Treatment of
PhCH2Br and CpFe(CO)2I. Synthesis and Character-
ization of Quadruple- and Triple-Butterfly Complexes
[(μ-SCSCH2Ph)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (11)
and [(μ-SCSFe(CO)2Cp)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-
SCH2)4C6H2] (12). We further found that, when excess CS2
was added to the tetrathiol system containing tetraanion A and
dianion B, the dithioformato ligand-containing intermediates
tetraanion C and dianion D were formed in a manner similar to
those reactions of the other μ-CO-containing Fe/S cluster
anions with CS2;17,19,40 further treatment of the intermediates
C and D with PhCH2Br and CpFe(CO)2I afforded the
quadruple- and triple-butterfly complexes 11 and 12 in 30%
and 12% yields, respectively (Scheme 8).
Complexes 7−10 are air-stable red solids, whose elemental
analysis and spectroscopic data are consistent with the
structures shown in Schemes 6 and 7. The IR spectra of 7−
10 showed three absorption bands in the range of 2074−1985
−1
cm for their terminal carbonyls and one absorption band at
1464, 1554, and 1495 or 1496 cm−1 for their bridged CO,
1
CN, and CC double bonds, respectively. The H NMR
spectra of 7−10 exhibited the corresponding signals for the
protons in their H-containing groups, such as 9 and 10 showing
two doublets at ca. 4.3 and 8.4 ppm for the two protons in their
bridged CHCH groups. The 13C NMR of 7−10 displayed
the corresponding signals for their carbon atoms, such as 7
showing a singlet at 292.1 ppm for its bridged CO groups,36
8 showing a singlet at 232.5 ppm for its bridged CN
groups,32 and 9/10 showing two singlets at ca. 96 and 144 ppm
for their PhCHCHFe groups.37 The molecular structure of 8
was confirmed by X-ray diffraction analysis. Its ORTEP plot is
shown in Figure 4, whereas Table 3 lists the selected bond
lengths and angles. Figure 4 shows that complex 8 is indeed a
triple-butterfly complex, which contains a closed butterfly
subcluster (μ-S)2Fe2(CO)6 and two identical open butterfly
subclusters (μ-S)(μ-PhCNPh)Fe2(CO)6, which are con-
nected to the methylene carbon atoms of the central moiety
1,2,4,5-(CH2)4C6H2. All the two phenyl groups bound to a C
N bond in the two open subclusters lie in a cis manner. The
N1−C28 (1.285 Å) and N2−C48 (1.269 Å) bonds in the two
μ-iminoacyl ligands of complex 8 could be best assigned to the
CN double bonds, but not the C−N single bonds, since the
normal bond lengths of a C−N single bond and a CN
double bond are 1.47 and 1.28 Å,38 respectively. Actually, such
a type of CN double bond was also observed in other μ-
iminoacyl bridged Fe/E (E = S, Se, Te) cluster complexes.32−34
An ORTEP drawing of 9 is shown in Figure 5, whereas its
selected bond lengths and angles are given in Table 3. Complex
9 possesses a symmetric center, namely, the center of the
benzene ring. As can be seen in Figure 5, complex 9 contains
four identical butterfly subclusters [(μ-σ,π-PhCHCH)-
Complexes 11 and 12 are also air-stable red solids, whose
elemental analysis and spectroscopic data are in good
agreement with the structures shown in Scheme 8. The IR
spectra of 11 and 12 showed three strong absorption bands in
the range of 2067−1985 cm−1 for their terminal carbonyls and
one absorption band at 1015 and 1004 cm−1 for their CS
functional groups coordinated to iron atoms. It is due to such a
coordination mode that the absorption bands of the
thiocarbonyl μ-SC−S groups in complexes 11 and 12 lie at
a much lower frequency than that of CS in free CS2 (1533
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Table 3. Selected Bond Lengths (Å) and Angles (deg) for 8 and 9
compound 8
Fe(1)−S(1)
Fe(3)−N(1)
2.2513(19)
1.992(6)
Fe(1)−Fe(2)
Fe(3)−S(3)
2.5167(14)
2.249(2)
Fe(3)−Fe(4)
Fe(5)−Fe(6)
N(1)−C(28)
2.5872(14)
2.5737(13)
1.285(9)
Fe(6)−N(2)
Fe(6)−S(4)
N(2)−C(48)
1.992(6)
2.2438(17)
1.269(8)
S(1)−Fe(1)−S(2)
N(1)−Fe(3)−S(3)
N(2)−Fe(6)−S(4)
S(3)−Fe(4)−Fe(3)
C(28)−Fe(4)−S(3)
87.49(7)
Fe(2)−S(1)−Fe(1)
N(1)−Fe(3)−Fe(4)
N(2)−Fe(6)−Fe(5)
S(4)−Fe(5)−Fe(6)
C(28)−N(1)−Fe(3)
68.02(6)
81.31(19)
79.95(16)
55.03(6)
70.77(19)
71.11(19)
54.94(5)
81.47(17)
109.4(5)
compound 9
Fe(1)−C(13)
Fe(1)−Fe(2)
Fe(1)−S(1)
Fe(2)−S(1)
1.974(8)
2.546(2)
2.252(3)
2.261(2)
2.278(3)
55.82(7)
68.68(8)
55.50(7)
52.6(2)
Fe(2)−C(13)
Fe(2)−C(14)
Fe(3)−Fe(4)
Fe(3)−S(2)
2.066(9)
2.266(8)
2.553(3)
2.213(3)
1.360(12)
56.56(7)
69.28(19)
54.16(8)
83.9(3)
Fe(4)−S(2)
C(13)−C(14)
S(1)−Fe(1)−Fe(2)
Fe(1)−S(1)−Fe(2)
S(1)−Fe(2)−Fe(1)
C(13)−Fe(1)−Fe(2)
Fe(1)−C(13)−Fe(2)
S(2)−Fe(3)−Fe(4)
Fe(3)−S(2)−Fe(4)
S(2)−Fe(4)−Fe(3)
C(13)−Fe(1)−S(1)
C(13)−Fe(2)−C(14)
78.1(3)
36.2(3)
S2−C1 (1.694 Å), but considerably shorter than the remote
single bonds S2−C2 (1.79 Å). In addition, the four identical
cluster units in 11 are joined together by connecting their μ-S
atoms with four benzylic C atoms of the central benzene ring
by equatorial-type bonds2,39 (for example, the nonbonded angle
C13−S4······S5 = 160.93°) in order to reduce the strong steric
repulsions between these bulky cluster moieties. It is worth
pointing out that, although some starlike triple-butterfly Fe2S2C
clusters with a central 1,3,5-trimethylenebenzene moiety40 and
some quadruple-butterfly clusters with a central 1,2,4,5-
tetramethylenebenzene moiety21 are known, complex 11 is
the first prepared and crystallographically characterized
quadruple-butterfly cluster in which its four butterfly Fe2S2C
cluster cores are connected to the central 1,2,4,5-tetramethy-
lenebenzene moiety.
CONCLUSIONS
■
Figure 5. Molecular structure of 9 with 30% probability level
ellipsoids.
A comparative study of the reactions of tetrathiol 1,2,4,5-
(HSCH2)4C6H2 with Fe3(CO)12 or with Fe3(CO)12 in the
presence of Et3N has allowed us to obtain a variety of the
1,2,4,5-(CH2)4C6H2 moiety-containing new butterfly Fe/S
cluster complexes. Thus, the reaction of tetrathiol 1,2,4,5-
(HSCH2)4C6H2 with Fe3(CO)12 is found to give the single-
butterfly complex 1 or single- and double-butterfly complexes
1/2 or 2/3, mainly dependent upon the molar ratio of the
starting materials and the reaction temperature in different
solvents. In addition, it is also found that further treatment of 1
with PPh3, PMe3, or N-heterocyclic carbene IMes affords its
monosubstituted derivatives 4, 5, and 6, respectively. More
interestingly, the quadruple-butterfly complex 7 can be
obtained by the reaction of 1,2,4,5-(HSCH2)4C6H2 with
Fe3(CO)12 in the presence of Et3N, followed by treatment of
the intermediate μ-CO-containing tetraanion A with PhCOCl,
and the triple-butterfly complex 8 is produced by reaction of
PhC(Cl)NPh with the μ-CO-containing dianion B, which is
generated in situ from the initially formed tetraanion A.
Similarly, the quadruple- and triple-butterfly complexes 9 and
10 are obtained by the reactions of PhCCH with tetraanion
cm−1) and falls within the range of 1120−860 cm−1 exhibited
by the coordinated CS in some other transition-metal
complexes.19,41 The 1H NMR spectrum of 11 exhibited a
multiplet centered at 4.25 ppm for the methylene protons
attached to its phenyl groups, whereas 12 displayed one singlet
at 4.97 ppm for its cyclopentadienyl ligands. In addition, the
13C NMR spectra of 11 and 12 exhibited four and six singlets in
the region of 206−213 ppm for their terminal carbonyls and
one singlet in the range of 303−319 ppm for their CS
groups.17
The molecular structure of complex 11 was further
confirmed by X-ray crystallography. Its ORTEP plot is shown
in Figure 6, and Table 4 lists its selected bond lengths and
angles. As can be seen in Figure 6, complex 11 is
centrosymmetric and consists of four identical butterfly [(μ-
SCSCH2Ph)Fe2(CO)6(μ-S)]4 cluster units. The bridged
CS double bonds (for example, the double bond C1S1
= 1.650 Å) is slightly shorter than its neighboring single bond
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Scheme 8
A and dianion B. Particularly interesting is that the
dithioformato ligand-containing quadruple-butterfly complex
11 can be obtained by the reaction of PhCH2Br with tetraanion
C (which is generated in situ from tetraanion A and CS2),
whereas the organometallic halide CpFe(CO)2I reacts with
dianion D (which is generated in situ from dianion B and CS2)
to give the corresponding triple-butterfly complex 12. While
complexes 1−12 have been characterized by elemental analysis,
various spectroscopic methods, and some of them by X-ray
crystallography, the suggested dithiol intermediate [1,2-
(HSCH2)2-4,5-(μ-SCH2)2C6H2][Fe2(CO)6] (M6) is isolated
in an anaerobic glovebox, and it has been proved to be able to
convert to complex 1 by oxidation in air.
EXPERIMENTAL SECTION
■
General Comments. Unless otherwise stated, all reactions were
carried out under an atmosphere of prepurified nitrogen by using
standard Schlenk and vacuum-line techniques. Tetrahedrofuran
(THF) and toluene were distilled from Na/benzophenone ketyl
under nitrogen. Fe3(CO)12,42 1,2,4,5-(HSCH2)4C6H2,43 PhC(Cl)
NPh,44 and CpFe(CO)2I,45 and (1,3-bis(mesityl)imidazolium chlor-
Figure 6. Molecular structure of 11 with 30% probability level
ellipsoids.
Table 4. Selected Bond Lengths (Å) and Angles (deg) for 11
Fe(1)−Fe(2)
Fe(3)−Fe(4)
Fe(2)−S(1)
Fe(2)−S(3)
2.6245(17)
2.6405(18)
2.255(4)
2.250(2)
2.258(3)
54.22(6)
83.07(16)
77.33(12)
53.84(6)
82.76(9)
Fe(4)−S(4)
Fe(4)−S(5)
S(5)−C(14)
S(6)−C(14)
2.244(2)
2.309(3)
1.647(9)
1.691(9)
1.843(8)
54.65(6)
71.13(7)
71.82(8)
94.1(4)
Fe(3)−S(4)
S(4)−C(13)
S(3)−Fe(1)−Fe(2)
S(3)−Fe(2)−S(1)
S(1)−Fe(2)−Fe(1)
S(4)−Fe(3)−Fe(4)
S(4)−Fe(4)−S(5)
S(3)−Fe(2)−Fe(1)
Fe(2)−S(3)−Fe(1)
Fe(4)−S(4)−Fe(3)
C(1)−S(1)−Fe(2)
S(1)−C(1)−S(2)
126.8(7)
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ide46 were prepared according to the literature procedures, whereas
the other starting materials were of commercial origin and used
without further purification. Preparative TLC was carried out on glass
plates (25 × 15 × 0.25) coated with silica gel G (10−40 μm). IR
spectra were recorded on a Bruker Vector 22 infrared spectropho-
subjected to TLC separation using deaerated petroleum ether/CH2Cl2
(2:1 v/v) as eluent to develop one major red band with many tiny
bands. From the major red band, M6 (0.180 g, 33%) was obtained as a
red air-stable solid (but in solution, it is air-sensitive). mp 111−113
°C. Anal. Calcd for C16H12Fe2O6S4: C, 35.57; H, 2.24. Found: C,
35.38; H, 2.41. IR (KBr disk): νCO 2074 (vs), 2033 (vs), 1995 (vs)
1
tometer. H (13C, 31P) NMR spectra were taken on a Bruker Avance
1
cm−1. H NMR (CDCl3, 300 MHz): 1.82 (t, 2H, J = 7.1 Hz, 2SH),
300 NMR or Bruker Avance 400 NMR spectrophotometer. Elemental
analyses were preformed with an Elementar Vario EL analyzer.
Melting points were determined on a Yanaco MP-500 apparatus and
are uncorrected.
3.07 (d, J = 12.9 Hz, 2H, 2CHHSFe), 3.76−3.86 (m, 6H, 2CHHSFe,
2CH2SH), 7.00 (s, 2H, C6H2) ppm. 13C NMR (CDCl3, 100 MHz):
24.5 (s, CH2SH), 34.8 (s, CH2SFe), 130.1, 137.6, 137.8 (3s, C6H2),
206.0 (s, CO) ppm.
Preparation of [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2][Fe2(CO)6]
(1) via Reaction of 1,2,4,5-(HSCH2)4C6H2 with Fe3(CO)12 in a 1:1
Molar Ratio in Refluxing THF. To a stirred solution of 1,2,4,5-
(HSCH2)4C6H2 (0.264 g, 1.00 mmol) in THF (20 mL) was added
Fe3(CO)12 (0.504 g, 1.00 mmol), and then the mixture was refluxed
for 1 h. After solvent was removed at reduced pressure, the residue was
subjected to open-air TLC separation using petroleum ether/CH2Cl2
(2:1 v/v) as eluent to develop one major red band with many tiny
bands. From the major red band, 1 (0.108 g, 20%) was obtained as a
red solid. mp 158−159 °C. Anal. Calcd for C16H10Fe2O6S4: C, 35.71;
H, 1.87. Found: C, 35.76; H, 2.00. IR (KBr disk): νCO 2072 (s), 2031
Conversion of Intermediate M6 to Complex 1. A solution of
M6 (0.108 g, 0.20 mmol) in toluene (10 mL) was stirred in air at 90
°C for about 10 min until TLC showed that M6 had completely
disappeared. After removal of solvent at reduced pressure, the residue
was subjected to TLC separation using petroleum ether/CH2Cl2 (2:1
v/v) to develop one major red band, from which 1 (0.076 g, 71%) was
obtained.
Preparation of [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)5PPh3] (4). A solution of 1 (0.108 g, 0.20 mmol), PPh3
(0.052 g, 0.20 mmol), and Me3NO·2H2O (0.022 g, 0.20 mmol) in
MeCN (10 mL) was stirred at room temperature for 1 h. After solvent
was removed under vacuum, the residue was subjected to open-air
TLC separation using petroleum/CH2Cl2 (2:1 v/v) as eluent. From
the major red band, 4 (0.045 g, 29%) was obtained as a red solid. mp
185−187 °C. Anal. Calcd for C33H25Fe2O5PS4: C, 51.31; H, 3.26.
Found: C, 51.25; H, 3.26. IR (KBr disk): νCO 2044 (vs), 1986 (vs),
1
(vs), 1990 (vs) cm−1. H NMR (CDCl3, 300 MHz): 3.07 (d, 2H, J =
12.6 Hz, 2CHHSFe), 3.80 (d, 2H, J = 12.3 Hz, 2CHHSFe), 3.97 (s,
4H, 2CH2S), 6.80 (s, 2H, C6H2) ppm. 13C NMR (CDCl3, 100 MHz):
34.2, 35.8 (2s, CH2S), 131.2, 132.8, 137.8 (3s, C6H2), 207.0 (s, CO)
ppm.
Preparation of Complex 1 and [1,2,4,5-(μ-SCH2)4C6H2]-
[Fe2(CO)6]2 (2) via Reaction of 1,2,4,5-(HSCH2)4C6H2 with
Fe3(CO)12 in a 1:2 Molar Ratio in Refluxing THF. To a stirred
solution of 1,2,4,5-(HSCH2)4C6H2 (0.132 g, 0.50 mmol) in THF (20
mL) was added Fe3(CO)12 (0.504 g, 1.00 mmol), and then the
mixture was refluxed for 1 h. After the same workup as that for the
above-described preparation of 1, two major red bands were
developed. From the upper red band, 1 (0.022 g, 8%) was obtained.
From the lower red band, 2 (0.088 g, 18%) was obtained as a red solid.
2: mp 191 °C (dec). Anal. Calcd for C22H10Fe4O12S4: C, 32.30; H,
1.23. Found: C, 32.22; H, 1.32. IR (KBr disk): νCO 2073 (s), 2032
1
1932 (s) cm−1. H NMR (CDCl3, 400 MHz): 3.07 (d, 2H, J = 10.8
Hz, 2CHHSFe), 3.83−3.97 (m, 6H, 2CHHSFe, 2CH2S), 6.62 (s, 2H,
C6H2), 7.46 (br s, 9H, 6o-H of 3C6H5, 3p-H of 3C6H5), 7.79 (br s, 6H,
6m-H of 3C6H5) ppm. 13C NMR (CDCl3, 100 MHz): 32.4, 34.2 (2s,
CH2S), 128.7, 128.8, 130.3, 130.9, 132.0, 133.5, 133.6, 135.2, 135.6,
138.8 (10s, C6H2, C6H5), 208.3, 212.5 (2s, CO) ppm. 31P NMR
(CDCl3, 162 MHz, 85% H3PO4): 64.53(s) ppm.
Preparation of [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)5PMe3] (5). The same procedure was followed as that for
preparation of 4, except PMe3 (0.20 mL, 1M, 0.20 mmol) was
employed in place of PPh3. 5 (0.033 g, 28%) was obtained as a red
solid. mp 170−172 °C. Anal. Calcd for C18H19Fe2O5PS4: C, 36.88; H,
3.27. Found: C, 37.01; H, 3.50. IR (KBr disk): νCO 2037 (vs), 1980
(vs), 1964 (vs), 1920 (s) cm−1. 1H NMR (CDCl3, 400 MHz): 1.43 (d,
9H, JP−H = 11.2 Hz, 3CH3), 3.07 (br s, 2H, 2CHHSFe), 3.72 (br s, 2H,
2CHHSFe), 3.96 (br s, 4H, 2CH2S), 6.75 (s, 2H, C6H2) ppm. 31P
NMR (CDCl3, 162 MHz, 85%H3PO4): 26.26(s) ppm. 13C NMR
(CDCl3, 100 MHz): 19.7(d, JP−C = 29.5 Hz, PCH3), 34.8, 37.7 (2s,
CH2S), 125.4, 125.7, 139.2, 139.4, 139.7, 139.9 (6s, C6H2), 209.4,
210.0 (2s, CO) ppm.
1
(vs), 1991 (vs) cm−1. H NMR (CDCl3, 300 MHz): 2.91−3.06 (m,
4H, 4CHHSFe), 3.71−3.82 (m, 4H, 4CHHSFe), 6.92 (s, 2H, C6H2)
ppm. 13C NMR (CDCl3, 100 MHz): 35.9, 37.6 (2s, CH2S), 125.8,
132.3, 133.0, 135.8, 137.0, 140.2 (6s, C6H2), 207.0, 208.3 (2s, CO)
ppm.
Preparation of Complex 1 via Reaction of 1,2,4,5-
(HSCH2)4C6H2 with Fe3(CO)12 in a 1:1 Molar Ratio in Toluene.
While stirring, Fe3(CO)12 (0.504 g, 1.00 mmol) was added to a
solution of 1,2,4,5-(HSCH2)4C6H2 (0.264 g, 1.00 mmol) in toluene
(20 mL). After the mixture continued to be stirred at about 90 °C for
1 h, solvent was removed at reduced pressure and the residue was
subjected to TLC separation using petroleum ether/CH2Cl2 (2:1, v/v)
as eluent. From the major red band, 1 (0.103 g, 19%) was obtained.
Preparation of Complex 2 and [(1,2-Me2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)6] (3) via Reaction of 1,2,4,5-(HSCH2)4C6H2 with
Fe3(CO)12 in a 1:2 Molar Ratio in Toluene. To a stirred solution
of 1,2,4,5-(HSCH2)4C6H2 (0.132 g, 0.50 mmol) in toluene (20 mL)
was added Fe3(CO)12 (0.504 g, 1.00 mmol), and then the mixture was
stirred at about 90 °C for 1 h. Through the same workup as that for
the above-described preparation of 1, two major bands were
developed. From the lower red band, 2 (0.088 g, 22%) was obtained
as a red solid. From the upper orange band, 3 (0.011 g, 5%) was
obtained as an orange-red solid. 3: mp 140−141 °C. Anal. Calcd for
C16H12Fe2O6S2: C, 40.37; H, 2.54. Found: C, 40.17; H, 2.47. IR (KBr
Preparation of [1,2-(CH2S2CH2)-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)5IMes] (6). To a stirred suspension of 1,3-bis(mesityl)-
imidazolium salt IMes·HCl (0.341 g, 1.00 mmol) in THF (15 mL)
was slowly added n-BuLi (0.40 mL, 2.5 M, 1.00 mmol in hexane) to
give a yellowish solution. After it was stirred at room temperature for
20 min, the reaction mixture was filtered under anaerobic conditions
through a Celite-packed column and eluted with THF (10 mL) to give
a filtrate containing the air-sensitive carbene IMes. To the filtrate was
added 1 (0.108 g, 0.20 mmol), and the new mixture was stirred at
room temperature for 2 h. The resulting mixture was evaporated to
dryness under vacuum to give a deep-red residue, which was subjected
to open-air TLC separation using petroleum/CH2Cl2 (2:1 v/v) as
eluent. From the brown-red band, 6 (0.036 g, 22%) was obtained as a
red solid. mp 163−164 °C. Anal. Calcd for C36H34Fe2N2O5S4: C,
53.08; H, 4.21; N, 3.44. Found: C, 52.79; H, 4.30; N, 3.52. IR (KBr
1
disk): νCO 2071 (s), 2036 (vs), 1985 (vs) cm−1. H NMR (CDCl3,
400 MHz): 2.19 (s, 6H, 2CH3), 3.08 (d, 2H, J = 12.8 Hz, 2CHHSFe),
3.79 (d, 2H, J = 12.8 Hz, 2CHHSFe), 6.83 (s, 2H, C6H2) ppm. 13C
NMR (CDCl3, 100 MHz): 19.3 (s, CH3), 36.0 (s, CH2S), 131.0,
136.5, 136.7 (3s, C6H2), 207.3 (s, CO) ppm.
1
disk): νCO 2035 (s), 1973 (vs), 1914 (m) cm−1. H NMR (CDCl3,
400 MHz): 2.26 (s, 12H, 4o-CH3 in 2C6H2 of IMes), 2.34 (s, 6H, 2p-
CH3 in 2C6H2 of IMes), 3.02 (d, 2H, J = 12.4 Hz, 2CHHSFe), 4.07 (d,
2H, J = 12.0 Hz, 2CHHSFe), 4.18−4.22 (m, 4H, 2CH2S), 6.76 (s, 2H,
C6H2), 7.03 (s, 4H, 4m-H of 2C6H2 in IMes), 7.13 (s, 2H, NCH
CHN) ppm. 13C NMR (CDCl3, 100 MHz): 18.6 (s, o-CH3 of
mesityl), 21.1 (s, p-CH3 of mesityl), 33.7, 37.6 (2s, CH2S), 125.1,
125.4 (2s, NCHCHN), 128.3, 129.5, 130.1, 132.4, 136.2, 137.7,
Isolation of Intermediate [1,2-(HSCH2)2-4,5-(μ-SCH2)2C6H2]-
[Fe2(CO)6] (M6). A mixture of 1,2,4,5-(HSCH2)4C6H2 (0.264 g, 1.00
mmol) and Fe3(CO)12 (0.504 g, 1.00 mmol) in toluene (15 mL) was
stirred at about 90 °C for 1 h. After removal of solvent at reduced
pressure, the residue was transferred to an anaerobic glovebox and
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Table 5. Crystal Data and Structure Refinement Details for 1, 3, and 4
1
3
4
mol formula
mol wt
cryst syst
space group
a/Å
C16H10Fe2O6S4
538.18
C16H12Fe2O6S2
476.08
C33H25Fe2O5PS4
772.44
triclinic
triclinic
triclinic
P1
P1
P1
̅
̅
̅
7.4687(15)
11.772(2)
12.307(3)
69.70(3)
72.76(3)
85.42(3)
968.9(3)
2
8.767(7)
9.768(8)
11.476(10)
97.411(8)
106.071(17)
93.711(15)
931.2(13)
2
11.381(5)
11.582(5)
13.538(6)
72.33(2)
77.97(2)
74.449(18)
1622.2(12)
2
b/Å
c/Å
α/deg
β/deg
γ/deg
V/Å3
Z
Dc/g·cm−3
abs coeff/mm−1
F(000)
index ranges
1.845
1.698
1.581
1.960
1.811
1.242
540
480
788
−8 ≤ h ≤ 8
−14 ≤ k ≤ 12
−14 ≤ l ≤ 14
5586
−10 ≤ h ≤ 11
−12 ≤ k ≤ 12
−15 ≤ l ≤ 15
10 760
−14 ≤ h ≤ 14
−15 ≤ k ≤ 14
−17 ≤ l ≤ 13
15 836
no. of reflns
no. of indep reflns
3373
4396
7627
2θmax/deg
50.04
55.82
55.86
R
0.0252
0.0234
0.0501
Rw
0.0622
0.0442
0.0791
goodness of fit
largest diff peak, hole/e Å−3
1.053
1.022
1.015
0.374/−0.341
0.321/−0.451
0.646/−0.711
139.4, 139.9 (8s, benzene rings), 195.6 (s, NCN), 213.6, 215.8 (2s,
CO) ppm.
room temperature for 3 h. From the lower major red band, 9 (0.108 g,
12%) was obtained as a dark-red solid. mp 78−79 °C. Anal. Calcd for
C66H38Fe8O24S4: C, 44.28; H, 2.14. Found: C, 44.19; H, 2.31. IR (KBr
disk): νCO 2070 (s), 2034 (vs), 1986 (vs); νCC 1495 (w) cm−1. 1H
NMR (400 MHz, CDCl3): 3.61 (s, 8H, 4CH2S), 4.26 (d, 4H, J = 14.0
Hz, 4C6H5CH), 7.09−7.29 (m, 22H, C6H2, 4C6H5), 8.42 (d, 4H, J =
13.6 Hz, 4FeCH) ppm. 13C NMR (CDCl3, 100 MHz): 39.9 (s,
CH2S), 95.7 (s, PhCHCHFe), 125.8, 127.3, 127.9, 129.0, 129.5,
132.1, 138.0, 139.0 (8s, C6H2, C6H5), 143.5 (s, PhCHCHFe), 209.3
(s, CO) ppm. From the upper band, 10 (0.161 g, 25%) was
obtained as an orange-red solid. mp 135−137 °C. Anal. Calcd for
C44H24Fe6O18S4: C, 40.53; H, 1.86. Found: C, 40.78; H, 1.95. IR (KBr
disk): νCO 2071 (s), 2033 (vs), 1987 (vs); νCC 1496 (w) cm−1. 1H
NMR (400 MHz, CDCl3): 3.08 (d, 2H, J = 12.4 Hz, 2CHHSFeS),
3.46−3.58 (m, 4H, 2CH2SFeC), 3.83 (d, 2H, J = 13.6 Hz,
2CHHSFeS), 4.24 (d, 2H, J = 13.6 Hz, 2C6H5CH), 6.96−7.19 (m,
12H, C6H2, 2C6H5), 8.42 (d, 2H, J = 13.6 Hz, 2FeCH) ppm. 13C
NMR (CDCl3, 100 MHz): 35.9, 39.6 (2s, CH2S), 95.7 (s, PhCH
CHFe), 125.8, 127.3, 127.9, 128.0, 129.0, 129.5, 131.4, 137.1, 139.0,
140.0 (10s, C6H2, C6H5), 143.4 (s, PhCHCHFe), 207.0, 209.3 (2s,
CO) ppm.
Preparation of [(μ-PhCO)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2]
(7). A mixture of 1,2,4,5-(HSCH2)4C6H2 (0.132 g, 0.50 mmol),
Fe3(CO)12 (1.00 g, 2.0 mmol), Et3N (0.28 mL, 2.0 mmol), and THF
(20 mL) was stirred at room temperature for 0.5 h to give a brown-red
solution. To this solution was added PhCOCl (0.53 mL, 4.0 mmol),
and then the new mixture was stirred at room temperature for 24 h.
After solvent was removed at reduced pressure, the residue was
subjected to open-air TLC separation using petroleum ether/CH2Cl2
(5:1 v/v) as eluent to develop a major red band with many tiny bands.
From the major red band, 7 (0.202 g, 22%) was obtained as a red
solid. mp 92 °C (dec). Anal. Calcd for C62H30Fe8O28S4: C, 41.42; H,
1.68. Found: C, 41.21; H, 1.72. IR (KBr disk): νCO 2074 (s), 2032
(vs), 1996 (vs); νCO 1464 (m) cm−1. 1H NMR (300 MHz, CDCl3):
3.00−3.94 (m, 8H, 4CH2S), 7.07−7.66 (m, 22H, C6H2, 4C6H5) ppm.
13C NMR (CDCl3, 100 MHz): 35.9, 39.2 (2s, CH2S), 127.3, 128.4,
128.9, 131.1, 132.2, 133.7, 134.0, 134.1, 137.8, 139.3, 139.9, 144.5
(12s, C6H2, C6H5), 207.0, 209.7, 211.1, 211.7(4s, CO), 292.1 (s,
CO)ppm.
Preparation of [(μ-PhCNPh)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-
SCH2)4C6H2] (8). The same procedure was followed as for 7, except
that PhC(Cl)NPh (0.862 g, 4.0 mmol) was used instead of
PhCOCl. From the major red band, 8 (0.132 g, 18%) was obtained as
a red solid. mp 104−105 °C. Anal. Calcd for C54H30Fe6N2O18S4: C,
44.48; H, 2.07; N, 1.92. Found: C, 44.55; H, 2.09; N, 2.11. IR (KBr
Preparation of [(μ-SCSCH2Ph)Fe2(CO)6]4[1,2,4,5-(μ-
SCH2)4C6H2] (11). A mixture of 1,2,4,5-(HSCH2)4C6H2 (0.132 g,
0.50 mmol), Fe3(CO)12 (1.00 g, 2.0 mmol), Et3N (0.28 mL, 2.0
mmol), and THF (20 mL) was stirred at room temperature for 0.5 h
to give a brown-red solution. To this solution was added CS2 (0.24
mL, 4.0 mmol), and then the mixture was stirred at −40 °C for about
0.5 h. After PhCH2Br (0.24 mL 2.0 mmol) was added, the new
mixture was stirred at room temperature for 24 h, and then solvent was
removed at reduced pressure to give a residue. The residue was
subjected to open-air TLC separation using petroleum ether/CH2Cl2
(5:1 v/v) as eluent to develop a major red band with many tiny bands.
From the major red band, 11 (0.305 g, 30%) was obtained as a red
solid. mp 107−109 °C. Anal. Calcd for C66H38Fe8O24S12: C, 38.73; H,
1.87. Found: C, 38.47; H, 1.89. IR (KBr disk): νCO 2067 (s), 2028
1
disk): νCO 2065 (s), 2025(vs), 1984 (vs); νCN 1554 (w) cm−1. H
NMR (400 MHz, CDCl3): 3.18 (d, 2H, J = 14.0 Hz, 2CHHSFeS),
3.91−4.16 (m, 6H, 2CH2SFeN, 2CHHSFeS), 6.51−7.17 (m, 22H,
C6H2, 4C6H5) ppm. 13C NMR (CDCl3, 100 MHz): 36.1, 40.5 (2s,
CH2S), 122.2, 123.7, 126.2, 127.7, 128.0, 128.9, 131.2, 137.9, 139.6,
146.7, 153.1(11s, C6H2, C6H5), 207.1, 208.7, 210.6, 213.4 (4s, CO),
232.5 (s, CN) ppm.
Preparation of [(μ-σ,π-PhCHCH)Fe2(CO)6]4[1,2,4,5-(μ-
SCH2)4C6H2] (9) and [(μ-σ,π-PhCHCH)Fe2(CO)6]2[Fe2(CO)6]-
[1,2,4,5-(μ-SCH2)4C6H2] (10). The same procedure was followed as
for 7, except that PhCCH (0.44 mL, 4.0 mmol) was utilized instead
of PhCOCl, and the new mixture was stirred at reflux for 1 h and at
1
(vs), 1991 (vs), νCS 1015 (s) cm−1. H NMR (CDCl3, 300 MHz):
3.88−3.93 (m, 8H, 4CH2S), 4.24−4.30 (m, 8H, 4CH2Ph), 7.07−7.29
(m, 22H, C6H2, 4C6H5) ppm. 13C NMR (CDCl3, 100 MHz): 36.0,
5368
dx.doi.org/10.1021/om300395z | Organometallics 2012, 31, 5358−5370

Organometallics
Article
Table 6. Crystal Data and Structure Refinement Details for 8, 9, and 11
8
9
11
mol formula
mol wt
cryst syst
space group
a/Å
C54H30Fe6N2O18S4·1.5CHCl3
1637.19
triclinic
C66H38Fe8O24S4·3CHCl3
2148.11
C66H38Fe8O24S12
2046.48
monoclinic
C2/c
triclinic
P1
P1
̅
̅
14.683(3)
15.6757(16)
17.2812(11)
102.0350(12)
109.7940(13)
109.8450(15)
3276.7(8)
2
13.034(3)
14.132(3)
14.763(3)
107.99(3)
107.29(3)
109.66(3)
2177.4(8)
1
22.827(3)
29.547(4)
13.0206(18)
90
b/Å
c/Å
α/deg
β/deg
101.027(2)
90
γ/deg
V/Å3
8620(2)
4
Z
Dc/g·cm−3
abs coeff/mm−1
F(000)
index ranges
1.659
1.638
1.577
1.672
1.734
1.664
1638
1072
4104
−17 ≤ h ≤ 16
−16 ≤ k ≤ 18
−19 ≤ l ≤ 20
21760
−15 ≤ h ≤ 15
−16 ≤ k ≤ 16
−17 ≤ l ≤ 17
16520
−22 ≤ h ≤27
−35 ≤ k ≤ 23
−15 ≤ l ≤ 11
21584
no. of reflns
no. of indep reflns
11429
7601
7592
2θmax/deg
50.04
50.04
50.02
R
0.0723
0.0903
0.0823
Rw
0.1850
0.2373
0.2075
goodness of fit
largest diff peak, hole/e Å−3
1.052
1.064
1.040
0.867/−1.376
1.451/−1.145
3.213/−0.869
41.8, 45.8 (3s, CH2S), 128.2, 129.1, 131.1, 133.2, 137.6, 137.7, 139.8
(7s, C6H2, C6H5), 206.7, 207.1, 210.6, 210.7 (4s, CO), 303.0 (s,
CS) ppm.
ASSOCIATED CONTENT
* Supporting Information
Full tables of crystal data, atomic coordinates and thermal
parameters, and bond lengths and angles for 1, 3, 4, 8, 9, and
11 as CIF files. This material is available free of charge via the
Internet at http://pubs.acs.org.
■
S
Preparation of [(μ-SCSFe(CO)2Cp)Fe2(CO)6]2[Fe2(CO)6]-
[1,2,4,5-(μ-SCH2)4C6H2] (12). The same procedure was taken as for
11, but CpFe(CO)2I (1.261 g, 4.0 mmol) was used instead of
PhCH2Br. From the major red band, 12 (0.100 g, 12%) was obtained
as a red solid. mp 128 °C (dec). Anal. Calcd for C44H20Fe8O22S8: C,
32.95; H, 1.26. Found: C, 32.71; H, 1.41. IR (KBr disk): νCO 2062
AUTHOR INFORMATION
Corresponding Author
*E-mail: lcsong@nankai.edu.cn.
■
1
(s), 2022 (vs), 1985 (vs); νCS 1004 (m) cm−1. H NMR (CDCl3,
400 MHz): 3.16 (d, 2H, J = 13.2 Hz, 2CHHSFeS), 3.79−3.94 (m, 6H,
2CHHSFeS, 2CH2SFeC), 4.97 (s, 10H, 2C5H5), 7.09, 7.12 (2s, 2H,
C6H2) ppm. 13C NMR (CDCl3, 100 MHz): 36.0, 42.0 (2s, CH2S),
85.9 (s, C5H5), 131.1, 138.2, 139.1 (3s, C6H2), 207.2, 207.7, 210.4,
210.6, 211.8, 212.7 (6s, CO), 317.8, 318.1(2s, CS) ppm.
X-ray Structure Determinations of 1, 3, 4, 8, 9, and 11. Single
crystals suitable for X-ray diffraction analyses were grown by slow
evaporation of the CHCl3/hexane solutions of 1, 8 and 9 or CH2Cl2/
hexane solutions of 3, 4, and 11 at −4 °C. A single crystal of 1, 3, 4, 8,
or 9 was mounted on a Rigaku MM-007 (rotating anode)
diffractometer equipped with a Saturn 70CCD. Data were collected
at 113 K by using a graphite monochromator with Mo Kα radiation (λ
= 0.71073) in the ω−ϕ scanning mode. Absorption correction was
performed by the CRYSTALCLEAR program.47 A single crystal of 11
was mounted on a Bruker APEX-II CCD diffractometer. Data were
collected at 173 K by using a graphite monochromator with Mo Kα
radiation (λ = 0.71073) in the ω−ϕ scanning mode. Absorption
correction was performed by the SADABS program.48 All the
structures were solved by direct methods using the SHELXS-97
program49 and refined by full-matrix least-squares techniques
(SHELXL-97)50 on F2. Hydrogen atoms were located using the
geometric method. Details of crystal data, data collections, and
structure refinements are summarized in Tables 5 and 6.
Notes
The authors declare no competing financial interest.
†Visiting professor on leave from the Chemistry and Chemical
Engineering College of Jinggangshan University, China.
ACKNOWLEDGMENTS
■
We are grateful to 973 (2011CB935902), the National Natural
Science Foundation of China (21132001, 20972073), and the
Tianjin Natural Science Foundation (09JCZDJC27900) for
financial support.
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