Synthesis and structures of dinuclear iron, molybdenum and tungsten complexes derived from (PhCHCHPh)-coupled bis(cyclopentadiene)

Article abstract of DOI:10.1016/j.jorganchem.2005.05.004

Reductive coupling of phenylfulvene with amalgamated calcium metal followed by hydrolysis yields CpPhCHCHPhCp (1) in high yield. Refluxing ligand 1 and Fe(CO)₅ in xylene produces (PhCHCHPh)-coupled bis(cyclopentadienyl) tetracarbonyl diiron (PhCHCHPh)[(η⁵-C₅H ₄)Fe(CO)₂]₂ (2) as a mixture of meso (2-meso) and racemic isomers (2-rac). The pure racemic isomers of the Mo and W analogues (3-rac and 4-rac) have been synthesized by lithiation of ligand 1 and addition of (MeCN)₃M(CO)₃ (M = Mo, W) followed by oxidation with 2 equiv. of ferrocenium tetrafluoroborate. All the new complexes have been fully characterized. The molecular structures of 1-meso, 2-meso, 2-rac, 3-rac, and 4-rac have been determined by X-ray diffraction analysis.

Full text of DOI:10.1016/j.jorganchem.2005.05.004

Journal of Organometallic Chemistry 690 (2005) 5309–5317
www.elsevier.com/locate/jorganchem
Synthesis and structures of dinuclear iron, molybdenum
and tungsten complexes derived from (PhCHCHPh)-coupled
bis(cyclopentadiene)
a
Bin Li , Baiquan Wang
a,b,
a
, Shansheng Xu , Xiuzhong Zhou
a
*
a
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, PR China
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
Shanghai 200032, PR China
b
Received 27 January 2005; received in revised form 6 April 2005; accepted 2 May 2005
Available online 21 June 2005
Abstract
Reductive coupling of phenylfulvene with amalgamated calcium metal followed by hydrolysis yields CpPhCHCHPhCp (1) in
high yield. Refluxing ligand 1 and Fe(CO) in xylene produces (PhCHCHPh)-coupled bis(cyclopentadienyl) tetracarbonyl diiron
5
5
( (2) as a mixture of meso (2-meso) and racemic isomers (2-rac). The pure racemic isomers of
the Mo and W analogues (3-rac and 4-rac) have been synthesized by lithiation of ligand 1 and addition of (MeCN)
PhCHCHPh)[(g -C
5
4
H )Fe(CO)
2
]
2
3
M(CO)
3
(
M = Mo, W) followed by oxidation with 2 equiv. of ferrocenium tetrafluoroborate. All the new complexes have been fully charac-
terized. The molecular structures of 1-meso, 2-meso, 2-rac, 3-rac, and 4-rac have been determined by X-ray diffraction analysis.
2005 Elsevier B.V. All rights reserved.
ꢀ
Keywords: Metal–metal bond; Cyclopentadienyl; Metal carbonyl
1
. Introduction
only a cis isomer, and maintains two metal centers in
close proximity, even after the metal–metal bond cleav-
age. The nature of a bridge has important effect on the
metal–metal bond and its reactivity. The single carbon
bridged bis(cyclopentadienyl) dinuclear iron, molybde-
num and tungsten carbonyl complexes in general have
the shortest metal–metal bonds [6–10], while the car-
bon and silicon doubly bridged bis(cyclopentadienyl)
dinuclear iron, molybdenum and tungsten carbonyl
complexes have the longest metal–metal bonds [9,11].
The tetramethyldisilylene or digermylene bridged
bis(cyclopentadienyl) tetracarbonyl diiron or diruthe-
The chemistry of the group 6 and 8 metal carbonyl
dimers with cyclopentadienyl-type ligands have been
intensively investigated as a class of organometallic
compounds [1–3]. Dinuclear metal complexes are often
postulated as simple models with which to study the
interactions of molecules with metal surfaces [4,5]. In
contrast to the unbridged bis(cyclopentadienyl) metal
carbonyl dimers, which exist both as trans and cis iso-
mers and form single metal sites after the metal–metal
bond cleavage, introduction of a bridge between the
two cyclopentadienyl ligands makes the complex as
5
nium complexes (Me EEMe )[(g -C H )M(CO)] (l-CO)
2
2
5
4
2
2
can occur a thermal rearrangement involving the
metathesis between the E–E (E = Si, Ge) and M–M
*
Corresponding author. Tel.: +86 22 23504781; fax: +86 22
3502458.
E-mail address: bqwang@nankai.edu.cn (B. Wang).
(M = Fe, Ru) bonds (Scheme 1) [12,13]. The Me C
bridged bis(cyclopentadienyl) and Me Si bridged
2
2
0
2
022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.05.004

5310
B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
H
C
Ph
C
H
C
H
C
Me
E
2
Ph
Ph
H
Ph
Me Me
2
2
CO
E
E
M CO
xylene
reflux
O
C
O
C
1
+
Fe(CO)5
+
O
C
Fe
Fe
Fe
Fe
xylene
C
O
CO
OC
C
O
CO
OC
OC
M
M
M
2-meso
2-rac
OC
C
O
CO
E
Me
CO
2
Scheme 3.
E = Si, Ge; M = Fe, Ru
Scheme 1.
H
C
H
C
Ph
Ph
bis(tetramethylcyclopentadienyl) tetracarbonyl diruthe-
nium complexes can undego photo rearrangement reac-
tions involving the cleavage of Ru–Ru bonds [14].
As a part of systematic study the structure–reactivity
relationship of the bridged bis(cyclopentadienyl or inde-
nyl) metal carbonyl dimers, especially the effect of the
bridge on the metal–metal bond length and its reactivity
MeCN)3M(CO)3 FcH
BF4
M = Mo 3-rac
M = W 4-rac
(
2
n-BuLi
1
M
M
(
CO)3 (CO)3
Scheme 4.
[
9,11–13], we synthesized the (PhCHCHPh)-bridged
mixture of racemic and meso isomers (70:30). Fortu-
nately, the pure meso isomer 1-meso suitable for X-ray
crystallography was obtained while the crude 1 was
bis(cyclopentadienyl) metal carbonyl dimers. One of
our primary goal is to test whether the thermal or photo
rearrangement undergoes in two carbon atoms bridged
analogues.
When ligand CpPhCHCHPhCp (1) reacted with
Ru (CO) , a new C–C cleavage product was produced
indeed except for the normal bridged bis(cyclopentadie-
nyl) metal carbonyl dimers (Scheme 2). However, it is
difficult to explain the result and the mechanism is still
under investigation, so the result will be described sepa-
1
recrystallized with pentane/CH Cl at À30 ꢁC. Its H
2
2
NMR spectrum shows Cp proton resonances at 6.30,
6.19, 6.05, and 5.82 ppm (ratio 1:1:1:1) and benzylic pro-
tons at 4.43 and 4.40 ppm, indicating the existence of a
pure isomer.
3
12
2.2. Crystal and molecular structures of 1-meso
rately later. But ligand 1 reacting with Fe(CO) and
5
The structure of 1-meso is similar to 2,3-dicyclopent-
adiene-2,3-dimethylbutane C H CMe CMe C H (6)
M(CO) (M = Mo, W) did not give the analogous C–C
6
5
5
2
2
5
5
cleavage products. Here, we describe the synthesis of
5
[17]. Two views of the molecular structure of 1-meso
are presented in Fig. 1. It followed the rules for substi-
tuted ethane and formed a staggered conformation with
the largest substituents in trans-position to minimize the
intramolecular steric interaction (see Fig. 1(b)). The
deviation from the tetrahedral angle around C(1) ranges
from 4.5ꢁ to 6ꢁ, which is larger than that of 6 [17]. The
(
PhCHCHPh)[(g -C H )Fe(CO) ] (2) (meso and rac
5
4
2 2
5
isomers) (Scheme 3) and (PhCHCHPh)[(g -C H )-
5
4
M(CO)3]2 [M = Mo (3-rac), W (4-rac)] (Scheme 4).
The molecular structures of 1-meso, 2-meso, 2-rac,
3-rac, and 4-rac determined by X-ray diffraction analysis
are also presented.
˚
C(1)–C(1A) bond distance of 1.456(8) A is much shorter
˚
than that of 6 [1.600(3) A] [17] and those in related
highly substituted and strained ethane, e.g., 2,3-di-
2
. Results and discussion
˚
methyl-2,3-di-p-tolybutane [1.590 A] [18], 2.3-dimethyl-
˚
2,3-diphenylbutane [1.598 A] [19] and 2.3-di-1-adaman-
˚
tyl-2,3-dimethylbutane [1.634 A] [20]. The shortness of
the central C(1)–C(1A) bond is due to the less steric
repulsion around C(1) and C(1A), compared to 6 and
other substituted ethane mentioned above.
2
.1. Synthesis and characterization of ligand 1
Ligand CpPhCHCHPhCp (1) was synthesized fol-
lowed the method of Shapiroꢀs group (reductive cou-
pling of phenylfulvene) [15] and Erkerꢀs group [16] as a
H
C
Ph
C
H
C
H
C
Ph
Ph
Ph
H
Ph
1
+
Ru3(CO)12
Ph
+
O
C
+
O
C
Ru
Ru
Ru
Ru
CO
Ru
Ru
CO
OC
CO
CO
CO
OC
C
O
OC
C
O
Scheme 2.

B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
5311
À1
À1
a
cm , and 1997(s), 1736(s) cm , respectively, indicating
the existence of both terminal and bridging carbonyl
groups. This is similar to many analogues such as
Me C[C H Fe(CO)] (l-CO) [6] and (Me SiSiMe )-
2
5
4
2
2
2
2
[
C H Fe(CO)] (l-CO) [12a].
5 4 2 2
The molecular structures of 2-meso and 2-rac are pre-
sented in Figs. 2 and 3, respectively. There are two inde-
pendent molecules with the ratio of 1/1 (A/B) in the unit
cell of 2-meso. One fourth of water molecule was also
found to incorporate in it. The two independent mole-
cules of 2-meso has slight different in Fe–Fe distance
[
˚
2.5134(13), 2.5106(12) A] and the dihedral angle be-
tween two cyclopentadienyl ring planes (90.1ꢁ, 89.4ꢁ),
while the torsion angle CEN-M1-M2-CEN (CEN is
the centroid of the five-membered ring) differs greatly
(2.4ꢁ, 0.3ꢁ). From the orientation of the two hydrogen
atoms at the bridge we can easily differentiate the two
isomers. The two phenyl groups arranging greatly differ-
ently are also due to their configurations. For 2-meso the
torsion angle C(21)–C(14)–C(15)–C(27) of 55.5(6)ꢁ in A
and C(45)–C(38)–C(39)–C(51) of 57.7(6)ꢁ in B are much
larger than that of 2-rac [torsion angle C(17)–C(15)–
b
C(16)–C(23) of 44.8(5)ꢁ]. The Fe–Fe distance in 2-meso
˚
average 2.5120 A) is a little longer than that in 2-rac
(
˚
2.5016(11) A]. In both 2-meso and 2-rac, the bridged
[
carbon atoms are bent out of the linked cyclopentadie-
˚
nyl planes by the range 0.1217–0.1852 A, so there is en-
ough space for the PhCHCHPh-bridge.
From the structural parameters of a series of bridged
bis(cyclopentadienyl) diiron complexes listed in Table 2,
it can found the following relation between the Fe–Fe
distance and the bridging group: R C < PhCHCHPh ꢀ
Fig. 1. Molecular structure of 1-meso. Thermal ellipsoids are shown at
the 30% level. (a) Side view. (b) View down the C(1)–C(1A) axis.
2
Me Si < Me SiSiMe < unbridged < doubly bridged.
Complex 2 has a shorter Fe–Fe distance than (Me Si-
2
2
2
˚
Selected bond lengths (A) and angles (ꢁ): C(1)–C(1A) = 1.456(8), C(1)–
C(8) = 1.510(5), C(1)–C(2) = 1.535(6), C(8)–C(12) = 1.353(5), C(8)–
2
SiMe )-bridged analogue (in despite of complex 2 has
2
C(9) = 1.392(5),
C(9)–C(10) = 1.411(6),
C(10)–C(11) = 1.379(6),
a larger \Cp–Cp fold angle) may due to the shorter
C–C distance than Si–Si distance and the less steric
repulsion between the four groups around the two
bridging atoms. More interestingly, the \Cp–Cp fold
C(11)–C(12) = 1.435(6); and C(1A)–C(1)–C(8) = 113.7(5), C(1A)–
C(1)–C(2) = 115.5(5), C(8)–C(1)–C(2) = 112.2(3), C(12)–C(8)–C(9) =
108.4(3), C(12)–C(8)–C(1) = 124.0(4), C(9)–C(8)–C(1) = 127.4(4),
C(8)–C(9)–C(10) = 108.0(4), C(11)–C(10)–C(9) = 108.2(4), C(10)–
C(11)–C(12) = 106.5(4), C(8)–C(12)–C(11) = 109.0(4).
angle has a reversed order: R C > PhCHCHPh ꢀ
2
Me Si > Me SiSiMe .
2
2
2
2.3. Synthesis and molecular structures of 2-meso and 2-
rac
2.4. Synthesis and molecular structures of 3-rac and 4-rac
Refluxing ligand 1 with M(CO) or (MeCN) M(CO)
3
6
3
Ligand 1 (as a mixture of racmic and meso isomers)
reacted with Fe(CO) in refluxing xylene for 24 h to give
(M = Mo, W) in DME, toluene or xylene only produced
very small amount of 3-rac (Mo) and 4-rac (W). Moder-
ate yields were got by lithiation of ligand 1 in THF and
addition of (MeCN) M(CO) (M = Mo, W) with heat-
5
5
(
PhHCCHPh)[(g -C H )Fe(CO)] (l-CO) (2-meso and
5 4 2 2
2
-rac) in low yield as dark red crystals (Scheme 3). No
3
3
C–C cleavage product was observed, even when 2-meso
and 2-rac were heated in refluxing xylene for 24 h. The
two isomers can be easily separated by column chro-
ing followed by oxidation with 2 equiv. of ferrocenium
tetrafluoroborate [24] (Scheme 4). To our surprise, only
1
3-rac and 4-rac were separated by this method. The H
1
matography. The observed differences of the H NMR
NMR spectra of 3-rac and 4-rac are similar to that of
2-rac. The IR spectra of 3-rac and 4-rac show only ter-
minal carbonyl groups that are close to uncoupled and
coupled analogues. In order to confirm the structure,
spectrum of 2-meso and 2-rac may simply due to aniso-
tropic differences. The IR spectra of 2-meso and 2-rac
shows a pattern of major bands at 1989(s), 1752(s)

5312
B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
a
b
Fig. 2. Molecular structure of 2-meso (two independent molecules in a cell). Thermal ellipsoids are shown at the 30% level. (a) side view. (b) view
˚
down the Fe–Fe axis. Selected bond lengths (A) and angles (ꢁ): (a) Fe(1)–Fe(2) = 2.5134(13), Fe(1)–C(9) = 2.130(5), Fe(2)–C(16) = 2.162(5),
C(9)–C(14) = 1.509(7), C(14)–C(15) = 1.567(7), C(15)–C(16) = 1.517(7), Fe(1)–C(9)–C(14) = 130.8(3), Fe(2)–C(16)–C(15) = 133.0(4), C(9)–C(14)–
C(15) = 119.6(4), C(14)–C(15)–C(16) = 113.4(4); and (b) Fe(3)–Fe(4) = 2.5106(12), Fe(3)–C(33) = 2.148(5), Fe(4)–C(40) = 2.162(5), C(33)–
C(38) = 1.513(7), C(38)–C(39) = 1.567(7), C(39)–C(40) = 1.523(7), Fe(3)–C(33)–C(38) = 130.8(3), Fe(4)–C(40)–C(39) = 133.7(3), C(33)–C(38)–
C(39) = 117.6(4), C(38)–C(39)–C(40) = 112.0(4).

B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
5313
Table 2
Structural parameter comparison for bis(cyclopentadienyl) diiron
complexes
b
Complexes
M–M
PL–PL Reference
a
(ꢁ)
˚
A)
(
cis-[CpFe(CO)]
2
(l-CO)
2
2.531(2)
2.534(2)
2.4836(6)
92.8
[21]
[22]
[6]
trans-[CpFe(CO)]
Me C[C
2
(l-CO)
2
2
5
H
4
Fe(CO)]
2
(l-CO)
2
109.6
1
09.3
(
CH
2
)
5
C[C
Si[C
C)(Me
cis-PhCHPhCH)-
Fe(CO)] (l-CO)
5
H
4
Fe(CO)]
Fe(CO)]
Si)[C
2
(l-CO)
2
2.466(1)
2.512(3)
108.4
97.2
[7]
Me
2
5
H
4
2
(l-CO)
Fe(CO)
2
[23]
[11]
tw
(
(
Me
2
2
5
H
3
2
]
2
2.7747(6)
2.5134(13)
126.9
90.1
[C
5
H
4
2
2
(2-meso)
2.5106(12)
2.5016(11)
89.4
93.1
(
(
trans-PhCHPhCH)-
Fe(CO)] (l-CO)
SiSiMe )[C
l-CO)
tw
[
C
5
H
4
2
2
(2-rac)
Me
2
2
5
H
4
Fe(CO)]
2
-
2.526(2)
85.3
[12a]
(
2
a
PL, plane of the cyclopentadienyl ring.
tw, this work.
b
plexes 3-rac and 4-rac are very similar. The two com-
plexes both possess crystallographically imposed C2
symmetry. The torsion angles C(10)–C(9)–C(9A)–
C(10A) of 43.4ꢁ for 3-rac and 44.6ꢁ for 4-rac are very
close to that of 2-rac. From the structural parameters
listed in Table 3 it also can found the effects of the
bridges on the metal–metal bond lengths. For the un-
bridged and singly bridged bis(cyclopentadienyl) dinu-
clear molybdenum and tungsten complexes, the M–M
bond length follows the order – R C < PhCHCHPh ꢀ
2
Me Si < Me SiSiMe < unbridged – similar to the diiron
2
2
2
analogues. The doubly bridged complexes (Me C)(Me -
2
2
Si)[C H M(CO) ] showed the longest M–M bond
5
3
3 2
lengths due to the inflexibility of the doubly bridged li-
gand [9]. Significantly, complexes 3-rac and 4-rac show
the smallest dihedral angle between two Cp ring planes
(108.1ꢁ and 109.3ꢁ, respectively), compared with the
uncoupled and coupled analogues. But the torsion angle
CEN-M1-M2-CEN of 3-rac (54.9ꢁ) and 4-rac (56.5ꢁ) are
the largest, which can also be attributed to the intramo-
lecular non-bonded interaction of the (PhCHCHPh)-
bridge.
Fig. 3. Molecular structure of 2-rac. Thermal ellipsoids are shown at
the 30% level. (a) Side view. (b) View down the Fe–Fe axis. Selected
˚
bond lengths (A) and angles (ꢁ): Fe(1)–Fe(2) = 2.5016(11), Fe(1)–
C(5) = 2.141(4), Fe(2)–C(10) = 2.154(4), C(5)–C(15) = 1.502(6), C(15)–
C(16) = 1.527(6), C(10)–C(16) = 1.504(6); and Fe(1)–C(5)–C(15) =
131.3(3), Fe(2)–C(10)–C(16) = 133.2(3), C(5)–C(15)–C(16) = 112.0(4),
C(15)–C(16)–C(10) = 113.4(3).
3. Experimental details
Schlenk and vacuum line techniques were employed
for all manipulations. Solvents were purified and de-
gassed by standard procedures prior to use. Phenylful-
vene [28], (MeCN) M(CO) (M = Mo, W) [29], and
X-ray structure determinations of 3-rac and 4-rac were
undertook.
3
3
The molecular structures of 3-rac and 4-rac are
shown in Figs. 4 and 5, respectively. The two hydrogen
atoms at the bridge clearly represent the configuration
of the two complexes. The molecular structures of com-
ferrocenium tetrafluoroborate [30] were prepared by
1
the literature procedures. H NMR spectra were re-
corded on a BRUKER AC-P200 or a Bruker AV300
spectrometer at room temperature. Chemical shifts for

5
1
314
B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
H NMR spectra were recorded in ppm relative to the
3.1. Synthesis of C H CHC H CHC H C H (1)
5 4 6 5 6 5 5 4
residual proton of CDCl (d 7.24). Infrared spectra were
3
obtained as KBr disks and recorded on a Nicolet 5DX
FT-IR spectrometer. Elemental analyses were per-
formed using a Perkin–Elmer 240C Elemental analyzer.
ESI Mass spectra were obtained using a Thermo Finni-
gan LCQ Advantage.
Ligand CpPhCHCHPhCp (1) was synthesized fol-
lowed the method of Shapiroꢀs group [15] and Erkerꢀs
group [16] as white solids in 60% yield. Mp: 105–
106 ꢁC. Anal. Calc. for C H : C, 92.86; H, 7.14.
2
4
22
Found: C, 92.63; H, 7.20. MS (ESI): m/z 311 (M + H).
Fig. 4. Molecular structure of 3-rac. Thermal ellipsoids are shown at
the 30% level. (a) Side view. (b) View down the Mo–Mo axis. Selected
Fig. 5. Molecular structure of 4-rac. Thermal ellipsoids are shown at
the 30% level. (a) Side view. (b) View down the W–W axis. Selected
˚
˚
bond lengths (A) and angles (ꢁ): Mo(1)–Mo(1A) = 3.1598(10), Mo(1)–
bond lengths (A) and angles (ꢁ): W(1)–W(1A) = 3.1488(10),
C(4) = 2.376(4),
Mo(1)–C(5) = 2.415(5),
Mo(1)–C(6) = 2.387(6),
W(1)–C(4) = 2.343(9), W(1)–C(5) = 2.325(10), W(1)–C(6) = 2.316(11),
W(1)–C(7) = 2.394(12), W(1)–C(8) = 2.427(10), C(4)–C(9) = 1.554(14),
C(9)–C(9A) = 1.50(2); and W(1)–C(4)–C(9) = 134.8(6), C(4)–C(9)–
C(9A) = 113.8(7).
Mo(1)–C(7) = 2.317(5), Mo(1)–C(8) = 2.335(5), C(4)–C(9) = 1.532(6),
C(9)–C(9A) = 1.521(9); and Mo(1)–C(4)–C(9) = 133.3(3), C(4)–C(9)–
C(9A) = 114.6(4).

B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
5315
Table 3
Structural parameter comparison for bis(cyclopentadienyl) dimolybdenum or ditungsten complexes
˚
a
b
Complexes
M–M (A)
PL–PL (ꢁ)
CEN-M-M-CEN torsion angles
Reference
trans-[CpMo(CO)
3
]
2
3.235(1)
3.1406
[25]
[8]
CH
CH
Me Si[C
C)(Me
2
[C
5
H
4
Mo(CO)
C[C Mo(CO)
Mo(CO)
5 3 3 2
Si)[C H Mo(CO) ]
3
]
2
(
2
)
5
5
H
4
3
]
2
3.1708(18)
3.2018(13)
3.4328(12)
3.1598(10)
3.1488(10)
3.222(1)
120.5
140.7
149.3
108.1
109.3
46.4
51.6
0
[9]
2
5
H
4
3
]
2
[26]
[9]
(
(
(
Me
2
2
trans-PhCHPhCH)[C
trans-PhCHPhCH)[C
5
H
H
4
Mo(CO)
W(CO)
3
]
2
(3-rac)
(4-rac)
54.9
56.5
tw
tw
5
4
3
]
2
trans-[CpW(CO)
CH [C W(CO)
CH C[C W(CO)
Me Si[C W(CO)
Me C)(Me Si)[C
CH )[C
3
]
2
[25]
[10]
[9]
2
5
H
4
3
]
2
3.166(1)
47.8(6)
45.3
(
2
)
5
5
H
4
3
]
2
3.1582(16)
3.196(1)
3.403(2)
120.4
149.2
2
5
H
4
3
]
2
ꢁ47.8
0
[27]
[9]
(
2
2
5
H
3
W(CO)
3
]
2
trans-(CH
2
2
9
H
6
W(CO)
3
]
2
3.1581(8)
50.5
[24]
a
CEN, centroid of the cyclopentadienyl ring.
tw, this work.
b
1
5
H NMR (CDCl , 300 MHz): 1 (mixture): 7.28–6.95 (m,
3
3.3. Preparation of rac-(CHC H CHC H )[(g -C H )-
6
5
6
5
5
4
total 20H, C H ), 6.47–6.43, 6.36–6.28, 6.21–6.16, 6.11,
6
M(CO)] (M = Mo (3-rac), W (4-rac))
3
5
6
4
2
.08–6.01, 5.82 (m, m, m, s, m, s, total 12H, –CH@),
.44, 4.42, 4.41, 4.37 (s, s, s, s, total 4H, PhCHCp),
To a solution of ligand 1 (0.58 g, 1.87 mmol) in
THF (30 mL) under argon was added dropwise n-bu-
tyl lithium hexane solution (1.98 mL, 1.89 M,
3.74 mmol), and the resulting mixture was stirred for
4 h. The lithium salt solution was added to a THF
solution of (MeCN) Mo-(CO) , prepared from
.89, 2.84, 2.73–2.65 (s, t, m, total 8H, –CH –). 1-meso:
2
d 7.28–7.09 (m, 10H, C H ), 6.32–6.28, 6.21–6.16, 6.08–
6.01, 5.82 (m, m, m, s, total 6H, –CH@), 4.44 (s, 1H,
PhCH Cp), 4.42 (s, 1H, PhCH Cp), 2.73–2.65 (m, 4H,
6
5
–
CH –).
2
3
3
Mo(CO) (1.00 g, 3.75 mmol) in refluxing acetonitrile
6
3
.2. Preparation of meso- and rac-(CHC H CHC H )-
6
(10 mL) over about 6 h. The resulting mixture was
heated under reflux for 18 h. The intense red solution
was then cooled to À78 ꢁC and [FeCp ][BF ] (1.02 g,
5
6
5
5
[
(g -C H )Fe(CO)] (l-CO) (2-meso and 2-rac)
5
4
2
2
2
4
To a solution of ligand 1 (0.93 g, 3.0 mmol) in 50 mL
of xylene was added Fe(CO) (1.0 mL, 7.6 mmol), and
the resulting mixture was refluxed for 24 h. After re-
moval of solvent under reduced pressure, the residue,
which was dissolved in a minimum of CH Cl and chro-
3.74 mmol) was quickly added. The solution was stir-
red for 1 h at low temperature, and then it was evap-
orated in vacuo. The residue was dissolved in
minimum of CH Cl and chromatographed on an alu-
5
2
2
mina column. Elution with petroleum ether/CH Cl
2
2
2
2
matographed on an alumina column using petroleum
ether/CH Cl as an eluent. The first brown band affords
oil, which could not be characterized. The second
brown-red band afforded 68 mg (4.2%) of 2-meso as
red crystals and the third brown band afforded 36 mg
(1:1) gave a red band, which afforded 0.51 g (41%)
of 3-rac as brown-red crystals. Mp: 165 ꢁC (dec.).
Anal. Calc. for C H Mo O : C, 53.91; H, 3.02.
2
2
3
0
20
2
6
1
Found: C, 53.90; H, 3.06.
300 MHz): 7.10–6.96 (m, 10H, C H ), 5.35 (s, 2H,
H NMR (CDCl3,
6
5
(
2.2%) of 2-rac as brown-red crystals. For 2-meso,
C H ), 5.19 (s, 4H, C H ), 4.98 (s, 2H, C H ), 4.21
5 4 5 4 5 4
À1
m.p.: 201 ꢁC (dec.). Anal. Calc. for C H Fe O : C,
6
(s, 2H, PhCHCp). IR (mCO, cm ): 2010 (s), 1954
(s), 1942 (s), 1914 (s), 1851 (s), 1839 (s).
2
8
20
2
4
1
3.20; H, 3.79. Found: C, 62.97; H, 3.66. H NMR
(
CDCl , 200 MHz): 7.23–7.07 (m, 6H, C H ), 6.90–
5
Complex 4-rac was prepared similarly as described
above for 3 from 1.0 g (2.85 mmol) of W(CO)6 and
0.44 g (1.42 mmol) of ligand 1 in 18% yield as red crys-
tals. Mp: 205 ꢁC (dec.). Anal. Calc. for C H W O : C,
3
6
6
C H ), 5.21 (s, 2H, C H ), 5.09 (s, 2H, C H ), 3.95 (s,
.82 (m, 4H, C H ), 5.29 (s, 2H, C H ), 5.24 (s, 2H,
6 5 5 4
5
4
5
4
5
4
À1
2
H, PhCHCp). IR (mCO, cm ): 2002 (s), 1989 (s), 1799
m), 1752 (s). For 2-rac, mp: 223 ꢁC (dec.). Anal. Calc.
for C H Fe O : C, 63.20; H, 3.79. Found: C, 63.06;
30
20
2
6
1
(
42.68; H, 2.39. Found: C, 42.67; H, 2.48. H NMR
(CDCl , 300 MHz): 7.12–6.92 (m, 10H, C H ), 5.45 (s,
3
2
8
20
1
2
4
6
5
H, 4.09. H NMR (CDCl , 200 MHz): 6.98–6.82 (m,
3
2H, C H ), 5.27 (t, 2H, C H ), 5.15 (t, 2H, C H ),
5 4 5 4 5 4
1
0H, C H ), 5.21 (s, 4H, C H ), 5.15 (s, 2H, C H ),
6
5.18 (s, 2H, C H ), 4.21 (s, 2H, PhCHCp). IR (mCO,
5 4
cm ): 2007 (s), 1953 (s), 1937 (s), 1902 (m), 1848 (m),
1832 (m).
5
5
4
5
4
À1
4
cm ): 1997 (s), 1958 (s), 1755 (s), 1736 (s).
.97 (s, 2H, C H ), 3.59 (s, 2H, PhCHCp). IR (mCO,
5
4
À1

5316
B. Li et al. / Journal of Organometallic Chemistry 690 (2005) 5309–5317
Table 1
Summary of crystallographic data for complexes 1-meso, 2-meso, 2-rac, 3-rac and 4-rac
1
-meso 2-meso Æ 1/4H 2-rac
2
O
3-rac
4-rac
Formula
C
24
H
22
C
28
H20.25Fe O
2 4.13
C
28
H20Fe
2
O
4
C
30
H20Mo
2
O
6
30 20 6 2
C H O W
Fw
310.42
Monoclinic
C2/c
534.39
Monoclinic
P2(1)/c
532.14
Monoclinic
C2/c
668.34
Tetragonal
I-42d
844.16
Tetragonal
I-42d
Crystal system
Space group
Unit cell dimensions
˚
a (A)
15.889(6)
7.991(3)
14.745(6)
90
21.350(7)
14.529(5)
15.659(5)
90
28.210(9)
12.670(5)
16.159(7)
90
19.636(3)
19.636(3)
13.670(5)
90
19.583(3)
19.583(3)
13.653(5)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
105.978(7)
90
105.154(7)
90
117.603(13)
90
90
90
90
90
˚
3
V (A )
1799.9(12)
4
1.146
4688(3)
8
1.514
5118(3)
8
1.381
5271(2)
8
5236(2)
8
Z
À3
D
calcd (g cm
)
1.684
0.995
2656
2.142
8.824
3168
À1
l (mm
F (00 0)
Cryst size (mm)
)
0.064
664
1.271
2186
1.164
2176
0.22 · 0.20 · 0.10
52.90
4098
0.18 · 0.12 · 0.06
52.86
26439
0.24 · 0.20 · 0.18
52.98
14289
0.24 · 0.18 · 0.16
52.78
11095
0.18 · 0.16 · 0.12
52.78
14481
Max. 2h (ꢁ)
No. of reflns. collected
No. of indep. reflns./Rint
No. of params.
1784/0.0363
109
1.016
9606/0.0838
622
1.056
5261/0.0543
307
1.089
2701/0.0644
172
1.017
2687/0.0594
172
1.022
2
Goodness-of-fit on F
R
R
1
1
, wR
, wR
2
2
(I > 2r(I))
(all data)
0.0794, 0.1996
0.1931, 0.2621
0.341 and À0.172
0.0637, 0.1072
0.1368, 0.1365
0.905 and À0.463
0.0486, 0.1274
0.0945, 0.1422
0.740 and À0.252
0.0391, 0.0599
0.0769, 0.0675
0.460 and À0.352
0.0347, 0.0702
0.0602, 0.0786
1.375 and À0.515
˚
Largest diff. peak and hole (e A
À3
)
3
.4. Crystallographic studies
Crystals of 1-meso, 2-meso, 2-rac, 3-rac, and 4-rac
20472037, 20421202), the Research Fund for the Doc-
toral Program of Higher Education (20030055001),
and the Program for New Century Excellent Talents
in University.
suitable for X-ray diffraction were obtained from
CH Cl -pentane or CH Cl -hexane solution. Data col-
lection was performed on a BRUKER SMART 1000,
2
2
2
2
References
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˚
(
x À 2h scans, k = 0.71073 A). Semi-empirical absorp-
[1] See the following chapters in: (a) G. Wilkinson, F.G.A. Stone,
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(
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