Crystal structures of [K(2.2.2-crypt)]4[Pb9Mo(CO) 3] - Isolation of the novel isomers [(η5-Pb 9)Mo(CO)3]4- beside [η4-Pb 9Mo(CO)3]4-

Article abstract of DOI:10.1002/ejic.200500060

The reaction of [Mo(CO)₃(MeCN)₃] with K ₄Pb₉ in the presence of 2.2.2-cryptand (2.2.2-crypt) has been investigated. The transition metal complex [K(2.2.2-crypt)] ₄[(η⁵-Pb₉)-Mo(CO)₃] (1), which contains a Pb₉^4- Zintl anion coordinated by Mo in an η⁵-fashion, is isolated for the first time and characterized by single-crystal X-ray structure analysis. The 10 metal atoms in the [(η⁵-Pb₉)Mo(CO)₃]^4- anion form a bi-capped square antiprism, with the Mo(CO)₃ unit occupying a waist vertex position. The IR spectra of single crystals, as well as of the crude product, show clearly that only the [(η⁵-Pb₉)Mo(CO) ₃]^4- ion is formed. In contrast, the reaction of [Mo(CO)₃(Mes)] with K₄Pb₉ under the same reaction conditions gives a mixture of compound 1 and its isomer [K(2.2.2-crypt)]₄[(η⁴-Pb₉)Mo(CO) ₃] (2). Compounds 1 and 2 were isolated without additional solvent molecules. The Pb-Mo, Pb-Pb, and Mo-C bond lengths and Mo-C-O bond angles in the η⁴- and η⁵-isomers are compared and the packing of compounds 1 and 2 is discussed. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200500060

FULL PAPER
Crystal Structures of [K(2.2.2-crypt)] [Pb Mo(CO) ] − Isolation of the Novel
4
9
3
5
4–
4
4–
Isomers [(η -Pb )Mo(CO) ] beside [(η -Pb )Mo(CO) ]
9
3
9
3
[a]
[a]
[a]
Li Yong, Stephan D. Hoffmann, and Thomas F. Fässler*
Dedicated to Prof. Dr. H. H. Karsch on the occasion of his 60th birthday
Keywords: Cluster compounds / Cryptands / Isomers / Packing / Zintl anions
The reaction of [Mo(CO)
ence of 2.2.2-cryptand (2.2.2-crypt) has been investigated.
The transition metal complex [K(2.2.2-crypt)]
3
(MeCN)
3
] with K
4
Pb
9
in the pres-
Pb
[Mo(CO)
tions gives a mixture of compound 1 and its isomer [K(2.2.2-
9
)Mo(CO)
3
]4– ion is formed. In contrast, the reaction of
Pb under the same reaction condi-
3
(Mes)] with K
4
9
5
4
[(η -Pb
9
)-
4
–
4
Mo(CO)
3
] (1), which contains a Pb
9
Zintl anion coordinated
4 9 3
crypt)] [(η -Pb )Mo(CO) ] (2). Compounds 1 and 2 were iso-
5
by Mo in an η -fashion, is isolated for the first time and char-
lated without additional solvent molecules. The Pb–Mo, Pb–
Pb, and Mo–C bond lengths and Mo–C–O bond angles in the
acterized by single-crystal X-ray structure analysis. The 10
5
4–
4
5
metal atoms in the [(η -Pb
9
)Mo(CO)
3
]
anion form a bi- η - and η -isomers are compared and the packing of com-
capped square antiprism, with the Mo(CO)
3
unit occupying
pounds 1 and 2 is discussed.
a waist vertex position. The IR spectra of single crystals, as
well as of the crude product, show clearly that only the [(η -
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
5
Introduction
mers and polymers have been reported so far. In the case
4–
4–
The chemistry of group 14 Zintl ions of the type E94– (E
of the heavier homoatomic Sn
9
and Pb
9
Zintl clusters
the research interests are mainly focused on their reaction
with transition metal complexes. Although a few cases con-
cerning the fragmentation of E94– Zintl ions and the forma-
tion of clusters of different sizes have been reported re-
=
Si, Ge, Sn, Pb) is of growing interest due to the remark-
able chemical reactivity of these clusters and their potential
application in the preparation of ligand-free nanomateri-
als.[ According to Wade’s rules, an E9 cluster adopts a
1]
4–
[
13]
cently,
in most cases the cluster ions stay intact and act
discrete nine-vertex, 22-electron structure with C4v point
as coordinating ligands to the transition metals. The re-
sulting 10-atom heteroatomic Zintl ions are also called “me-
talated Zintl ions”. The first NMR experiments involving
symmetry which can be described as a monocapped dis-
torted square antiprism.[ In the case of the Ge9 cluster,
2]
4–
progress has been made in the field of oxidative coupling
reactions of these Zintl anions. Smaller oligomers such as
the dimeric [Ge –Ge ] , the trimeric [Ge =Ge =Ge ] ,
the reaction of E94– anions (E = Sn, Pb) with [Pt(PPh ) ] in
3 4
ethylenediamine (en) were described by Rudolph in 1983.[
However, up to now only a few structurally characterized
metalated Zintl ions have been reported, most of which are
14]
6
– [3]
6– [4]
9
9
9
9
9
8
–[5,6]
and the tetrameric [Ge =Ge =Ge =Ge ]
and poly-
9
9
9
9
[7]
meric representatives have been reported. Recently, a
4
–
polymeric anion [HgGe9]2– with Zintl ions as building
1
polystannide complexes, including [Sn
9
M(CO)
3
]
(M = Cr,
ϱ
[
15–17]
2– [18]
3– [18]
Mo, W),
[Sn Pt (PPh )] ,
and [Sn Ni (CO)] .
9 2 3
9
2
blocks covalently linked by heteroatoms has been reported
4–
[
8]
Although the first synthesis of the Pb
9
Zintl ion by Jo-
annis dates back to 1891, and several important synthetic
by our group. Nucleophilic addition of BiPh and SbPh3
3
[
19]
has also been realized in order to synthesize functionalized
4
–
2
–[9]
routes for the preparation of Pb
9
have been developed
with transition metal
clusters like [Ph Bi–Ge –BiPh ]
and [Ph Sb–Ge –Sb-
2
9
2
2 9
[
20]
4–
2
– [10]
since then,
the reaction of Pb
9
Ph ] . In the case of the Ge clusters, only one transition
2
2–
complexes has remained almost unexplored, and only three
metal complex of the composition [Ge {Cr(CO) } ] is
6
5 6
4–
[
11]
metalated complexes of the composition [Pb
9
M(CO)
It is worth pointing
ion has been characterized in
3
]
(M
known so far.
[
16,21]
=
Cr, Mo, W) have been reported.
Oxidative coupling reactions of the heavier homoatomic
4–
Sn94– cluster have also been studied,[12] although no oligo-
out that the [Pb
9
Mo(CO) ]
3
the salt Mo(CO) (en) [K(2.2.2-crypt)] [Pb Mo(CO) ]·2.5en
3
2
4
9
3
[
a] Department Chemie, Technische Universität München,
Lichtenbergstraße 4, 85747 Garching, Germany
Fax: +49-89-289-13186
(
(
3), although it could not be obtained without Mo(CO) -
3
[
16]
en)2.
In the reported complexes the ML fragment usu-
n
4–
E-mail: thomas.faessler@lrz.tum.de
ally resides in a capping position, with the nido-E9 ion
Eur. J. Inorg. Chem. 2005, 3663–3669
DOI: 10.1002/ejic.200500060
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3663

L. Yong, S. D. Hoffmann, T. F. Fässler
FULL PAPER
4
bound to the metal atom in an η -coordinative fashion
Scheme 1).
The reaction of K Pb with [Mo(CO) (Mes)] under the
4
9
3
(
same reaction conditions afforded an isomeric mixture of
4
[
[
K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] (2) and [K(2.2.2-crypt)] -
4 9 3 4
5
(η -Pb )Mo(CO) ] (1). Surprisingly, compound 2 obtained
9
3
under these reaction conditions is solvate-free and does not
contain an additional Mo(CO) fragment as reported for
3
[
16]
compound 3.
Repetition of the reaction led to variable
ratios of the two isomers.
Scheme 1.
Crystal Structure Analyses of Compounds 1 and 2
5
Recently, Eichhorn has reported an η -coordinated Zintl
4
–
Compound 1
ion [Sn W(CO) ] , in which the W(CO) unit occupies a
9
3
3
[
17]
waist vertex rather than sitting in a capping position. The
The crystal structure analysis of compound 1 shows that
5
5
4–
obtained product turned out to be a mixture of the η - and the unit cell contains two [(η -Pb
)Mo(CO)
]
anions and
9
3
4
4–
+
η -isomers in a ratio of 2:1. Metalated Sn
analogs of eight [K(2.2.2-crypt)] cations. Four 2.2.2-crypt-coordi-
9
4
–
4–
5
+
Ge9 and Pb9 acting as an η -ligand to a transition metal nated K cations per cluster clearly indicate a charge alloca-
are still unknown. [M(CO) (Mes)] (M = Cr, Mo, W) com- tion of –4 for the 10-atom heteroatomic polyanion. Four
3
+
plexes are the most frequently used organometallic com- [K(2.2.2-crypt)] units surround the cluster unit at a dis-
plexes for the reaction with E94 Zintl ions, whereas their tance where interionic interactions can be excluded. The
–
reaction with [M(CO) (MeCN) ] is still unexplored to the shortest Pb–K distance is 7.195 Å. During the refinement,
3
3
best of our knowledge. Herein we report the reaction of relatively large difference Fourier peaks were located near
K Pb with [Mo(CO) (MeCN) ] and the isolation of the the Pb atoms, indicating a disorder of the anions which
4
9
3
3
5
4–
first representative of a metalated η -Pb Zintl ion in the could be resolved by applying a split model (ratio
solvate-free compound [K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] 0.85:0.15). A very similar disorder, even as far as the ratio
1), where 2.2.2-crypt stands for 4,7,13,16,21,24-hexaoxa- of occupation is concerned, has been observed for [(η -Sn )-
9
5
4
9
3
5
(
1
9
4
–
,10-diazabicyclo[8.8.8]hexacosane. According to the re- Mo(CO)
As emphasized in Figure 1, the [(η -Pb
sively the η -isomer. The reaction of K Pb with [Mo- forms a bicapped square antiprism. The most important
] .
3
5
)Mo(CO)
]4– ion
9 3
sults of IR and X-ray analyses, the reaction affords exclu-
5
4
9
(
CO) (Mes)] was also reinvestigated under the same reac- feature of this polyhedron is that the Mo(CO)
3
unit occu-
3
[
16]
tion conditions. In contrast to the previous report,
we pies a waist vertex. This closo antiprism is built up by a
observed the formation of compound 1 together with its η - bottom square plane (Pb2–Pb5), a top square plane (Pb6–
4
4
isomer [K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] (2).
Pb8 and Mo), and two capping atoms (Pb1, Pb9). The data
of the crystal structure determination of compound 1 are
listed in the Exp. Sect., and selected bond lengths and
4
9
3
5
[
K(2.2.2-crypt)]
4
4
[(η -Pb
9
)Mo(CO)
)Mo(CO)
3
3
] (1)
] (2)
5
4–
angles for [(η -Pb )Mo(CO) ] are given in Table 1. The
4
9
3
5
[
K(2.2.2-crypt)]
[(η -Pb
9
4–
Mo–Pb bond lengths in [(η -Pb )Mo(CO) ] are different
9
3
4
Mo(CO)
3
(en)
2
[K(2.2.2-crypt)]
4
[(η -Pb
9
3
)Mo(CO) ]·2.5en (3)
(Table 1), with the contacts of the Mo atom to the apical
K
2
[K(2.2-crypt)]
2
[Pb {Mo(CO)
5
3
}
2
](en)
3
(4)
Pb9 atom and to the Pb2 and Pb5 atoms of the bottom
square being remarkably shorter (2.962–3.063 Å) than
those to the atoms Pb6 and Pb8 of the top square plane
Results and Discussion
(3.220–3.241 Å). Since these two longer Mo–Pb distances
are comparable to the two Pb–Pb contacts within the top
square plane (3.278–3.285 Å), the whole cluster can be re-
Synthesis of Compounds 1 and 2
5
[
K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] (1) was prepared by garded as regularly shaped, even though the Mo(CO) unit
4
9
3
3
the slow addition of a toluene solution of [Mo(CO) - is in a waist position. Due to the higher coordination
3
[
22]
5
4–
(
MeCN)3] to a solution of K Pb in ethylenediamine (en) number of the Mo atom in [(η -Pb )Mo(CO) ] , the mean
4
9
9
3
in the presence of 4 equiv. of 2.2.2-crypt. Within 2 h the Mo–Pb distance of 3.1074 Å is slightly longer than that in
4
color of the resulting reaction mixture changed from deep the η -isomers (3.028 and 3.032 Å) in compounds 2 and
[
16]
grey to deep reddish-brown. After careful layering with tol-
3
(Table 2). This distance is also significantly longer than
uene, single crystals of compound 1 started to grow on the the sum of the covalent radii of the metals involved
[
23]
walls of the vessel and became visible within a few hours. (2.834 Å). The Pb–Pb distances within the top plane are
After one week the solution became colorless, indicating the approximately 0.2 Å longer than those in the bottom plane.
completeness of the crystallization. Black crystals suitable However, the angles within the bottom plane (90.0± 0.9°)
for single-crystal X-ray diffraction studies were obtained. lie within a narrower range than those in the top plane
No additional phases were formed, since the unit cells of (90.0± 2.9°). Similar to the different W–C distances in the
5
4
4–
several crystals of compound 1 were checked by X-ray dif- related η - and η -[(Sn )W(CO) ] complexes, the corre-
9
3
5
5
4–
fraction and all of them turned out to be the η -complex.
sponding Mo–C distances in [(η -Pb )Mo(CO) ]
are
9
3
3664
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3663–3669

4 9 3
Crystal Structures of [K(2.2.2-crypt)] [Pb Mo(CO) ]
FULL PAPER
4
4–
5
4–[17]
longer (1.90 Å) than those in the η -isomer (1.88 Å). The bonyl-containing E9 moieties like [(η -Sn )W(CO) ]
9
3
5
4–
4
4– [16]
C–O bonds in [(η -Pb )Mo(CO) ] are in the range from and [(η -Pb )Mo(CO) ] ,
.22 to 1.23 Å and are therefore shorter than those in [(η - (Mes)].
Pb )Mo(CO) ] (1.22–1.27 Å). The Mo–C–O bond angles
in [(η -Pb )Mo(CO) ] deviate strongly from linearity and
and also to [Mo(CO)3-
9
3
9
3
4
[21]
1
4
–
9
3
5
4–
Compound 2
9
3
range from 167 to 171°, which is in contrast to other car-
The crystal structure analysis of compound 2 shows that
4
4–
the unit cell contains four [(η -Pb )Mo(CO) ] anions and
9
3
+
sixteen [K(2.2.2-crypt)] cations. Four 2.2.2-crypt-bound
K cations per cluster allow the clear charge allocation of
+
–
4 for the 10-atom heteroatomic polyanion. As observed in
+
compound 1, the four [K(2.2.2-crypt)] units in compound
are at a large distance from the polyanion and show no
2
coordination to the cluster anion. The distances between
+
the K cations and the polyanions are longer than 7.37 Å.
Due to the poor quality of the crystals the reflex intensities
were low, and during the refinement relatively large differ-
ence Fourier peaks were located near the Pb atoms, indicat-
ing a disorder of the anions. Attempts to resolve the disor-
5
9 3
Figure 1. Molecular structure of the closo-[(η -Pb )Mo(CO)
]4–
der were not successful.
4
As shown in Figure 2, the metal atoms of the [(η -Pb )-
unit in compound 1 (thermal ellipsoids set at 80% probability).
9
Mo(CO)3]4– ion again form a bicapped square antiprism,
5
Table 1. Selected bond lengths [Å] and angles [°] for the [(η -Pb
9
)- but this time with the Mo(CO)
The closo antiprism is built up by a bottom square plane
Pb2–Pb5), a top square plane (Pb6–Pb9), and two capping
3
unit in a capping position.
4–
Mo(CO)
3
]
unit in compound 1.
(
Mo1–Pb2
Mo1–Pb5
Mo1–Pb6
Mo1–Pb8
Mo1–Pb9
Pb1–Pb2
Pb1–Pb3
Pb1–Pb4
Pb1–Pb5
Pb2–Pb3
Pb2–Pb5
Pb2–Pb8
Pb3–Pb4
Pb3–Pb7
Pb3–Pb8
3.063(1)
3.051(1)
3.220(1)
3.241(1)
2.962(1)
3.069(1)
3.055(1)
3.060(1)
3.070(1)
3.415(1)
3.272(1)
3.038(1)
3.211(1)
3.100(1)
3.157(1)
167(1)
Pb4–Pb5
Pb4–Pb6
Pb4–Pb7
Pb5–Pb6
Pb6–Pb7
Pb6–Pb9
Pb7–Pb8
Pb7–Pb9
Pb8–Pb9
Mo1–C1
Mo1–C2
Mo1–C3
C1–O1
3.390(1)
3.186(1)
3.070(1)
3.011(1)
3.278(1)
3.026(1)
3.285(1)
3.198(1)
3.034(1)
1.92(1)
1.89(1)
1.89(2)
1.22(2)
1.22(2)
1.23(2)
91.9(6)
93.1(6)
95.6(6)
atoms (Pb1, Mo). The data of the crystal structure determi-
nation of compound 2 are listed in the Exp. Sect., and se-
lected bond lengths and angles for the [(η -Pb )Mo(CO) ]
anion are given in Table 3. The contacts between the Mo
atom and Pb6, Pb7, Pb8, and Pb9 of the top square plane
are in the narrow range between 3.014 and 3.048 Å (average
4
4–
9
3
3.028 Å), and are shorter than those observed in com-
pounds 1 (average 3.107 Å) and 3 (average 3.032 Å). The
Pb–Pb distances within the top plane range from 3.180 to
3.222 Å and are shorter than those within the bottom plane
C2–O2
C3–O3
C1–Mo1–C2
C1–Mo1–C3
C2–Mo1–C3
(3.249–3.428 Å). The Pb–Pb distances between the apical
Pb1 and Pb2, Pb3, Pb4, and Pb5 of the bottom plane lie
between 3.048 and 3.089 Å (average 3.074 Å) and are longer
than those in compounds 1 (average 3.064 Å) and 3
(average 3.048 Å). The two planes have similar dimensions,
which gives rise to a more regularly shaped 10-atom cluster
than that observed in compounds 1 and 3. The Pb–Pb dis-
tances within the top plane are approximately 0.122 Å
shorter than those within the bottom plane. However, the
angles within the top plane (90.0± 0.9°) lie within a nar-
rower range than those within the bottom plane
O1–C1–Mo1
O2–C2–Mo1
O3–C3–Mo1
167(1)
171(1)
Pb5–Mo1–Pb9
Pb2–Mo1–Pb9
Pb2–Mo1–Pb6
Pb5–Mo1–Pb8
Pb6–Mo1–Pb8
Mo1–Pb6–Pb7
Pb6–Pb7–Pb8
Mo1–Pb8–Pb7
112.38(4)
112.82(4)
102.57(3)
101.72(3)
88.79(3)
92.33(3)
87.05(2)
91.82(3)
Pb2–Pb1–Pb4 100.35(2)
Pb3–Pb1–Pb5
Mo1–Pb9–Pb7
Pb6–Pb9–Pb8
Pb3–Pb2–Pb5
Pb2–Pb3–Pb4
Pb3–Pb4–Pb5
Pb2–Pb5–Pb4
99.96(2)
99.02(3)
96.47(2)
89.07(2)
90.49(2)
90.54(2)
89.90(2)
(
90.0± 1.9°). In this respect, compound 2 is quite different
Table 2. Structural comparison of the anions in compounds 1, 2,
and 3.
from compounds 1 and 3.
Although compounds 2 and 3 contain the same polyhe-
dral core of 10 atoms, the Mo–C–O bond angles in these
two compounds are significantly different (Table 2). The
1[a]
2[a]
3[b]
Mean d(Pb1 to Pb2, 3, 4, 5) [Å]
3.064
3.074
3.048
Mean d(Pb–Pb) in bottom plane [Å][
c]
3.322
3.256
3.107
1.90
3.320 3.319 mean Mo–C–O bond angle (178°) in compound 3 is almost
Mean d(Pb–Pb/Pb–Mo) in top plane [Å]
Mean d(Mo–Pb) [Å]
Mean d(Mo–C) [Å]
3.202
3.028
1.88
3.207
3.032
1.93
linear, whereas the corresponding angle in compound 2 de-
viates strongly from linearity (172°). As shown in Table 2,
the Pb–Pb bond lengths within the bottom planes are al-
most identical (3.322 vs. 3.320 Å) despite the different loca-
Mean d(C–O) [Å]
Mean Mo–C–O [ ]
1.22
168
1.23
172
1.18
178
o
a] This work. [b] Ref.[16] [c] The square plane containing the atoms
Pb2, Pb3, Pb4, and Pb5 is defined as the bottom plane; the other
tion of the Mo(CO)
Mo–Pb distance in the η -isomer is a consequence of the
square plane in the 10-atom polyhedra is defined as the top plane. higher coordination number. The two elongated bonds
3
fragment. The elongation of the mean
[
5
Eur. J. Inorg. Chem. 2005, 3663–3669
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3665

L. Yong, S. D. Hoffmann, T. F. Fässler
FULL PAPER
(average 3.041 Å) in compound 4 are significantly shorter
than those in compounds 1 and 2 (dPb–Pb = 3.011–3.415 Å
and 3.048–3.428 Å, respectively). Interestingly, the Mo–Pb
distances (3.014–3.048 Å) in compound 2 are very similar
to those in compound 4 (3.001–3.093 Å), but differ from
those in compound 1 (2.962–3.241 Å). Compound 1 can be
regarded as an intermediate in the fragmentation of the
Pb94– cluster and the formation of the novel Pb cluster
5
fragment in 4 (Figure 3).
4
9 3
Figure 2. Molecular structure of the closo-[(η -Pb )Mo(CO)
]4–
unit in compound 2 (thermal ellipsoids set at 50% probability).
4
Table 3. Selected bond lengths [Å] and angles [°] for the [(η -Pb
9
)-
4–
Mo(CO)
3
]
unit in compound 2.
5
]4–
9 3
Figure 3. (a) Molecular structure of the closo-[(η -Pb )Mo(CO)
unit in compound 1 (thermal ellipsoids set at 80% probability) (dot-
Mo1–Pb6
Mo1–Pb7
Mo1–Pb8
Mo1–Pb9
Pb1–Pb2
Pb1–Pb3
Pb1–Pb4
Pb1–Pb5
Pb2–Pb3
Pb2–Pb5
Pb2–Pb8
Pb2–Pb9
Pb3–Pb4
Pb3–Pb7
Pb3–Pb8
O1–C1–Mo1
O2–C2–Mo1
O3–C3–Mo1
Pb7–Mo1–Pb9
Pb6–Mo1–Pb8
Pb3–Pb2–Pb5
Pb2–Pb3–Pb4
Pb3–Pb4–Pb5
Pb2–Pb5–Pb4
3.030(5)
3.017(4)
3.048(4)
3.014(4)
3.048(3)
3.087(3)
3.089(3)
3.072(3)
3.428(3)
3.293(3)
3.100(3)
3.063(3)
3.309(3)
3.100(3)
3.149(3)
173(4)
171(4)
172(4)
97.0(1)
96.7(1)
88.79(6)
88.11(6)
91.63(7)
91.47(7)
Pb4–Pb5
Pb4–Pb6
Pb4–Pb7
Pb5–Pb6
Pb5–Pb9
Pb6–Pb7
Pb6–Pb9
Pb7–Pb8
Pb8–Pb9
Mo1–C1
Mo1–C2
Mo1–C3
C1–O1
C2–O2
C3–O3
C1–Mo1–C2
C1–Mo1–C3
C2–Mo1–C3
Pb2–Pb1–Pb4
Pb3–Pb1–Pb5
Pb7–Pb6–Pb9
Pb6–Pb7–Pb8
Pb7–Pb8–Pb9
Pb6–Pb9–Pb8
3.249(3)
3.137(3)
3.207(3)
3.115(3)
3.138(3)
3.222(3)
3.192(2)
3.215(3)
3.180(2)
1.83(5)
1.90(5)
1.92(5)
1.27(5)
1.21(5)
1.21(5)
92(2)
ted lines represent Mo–Pb distances Ͼ3.2 Å). (b) The structure of
5
4–
the closo-[η -Pb
5
{Mo(CO)
3
}
2
]
Zintl anion (thermal ellipsoids set
at 80% probability).
Cluster Arrangements
The packing diagrams of compounds 1 and 2 are shown
in Figures 4 and 5, respectively. Both compounds form dis-
torted hexagonal layers. The distances between the cluster
units within the same layers differ by less than 10% (dis-
tance range for 1 from 15.465 to 16.774 Å and for 2 from
1
5.066 to 16.477 Å). In compound 1 the interlayer distances
between the centers of gravity of the clusters are 15.493,
5.853 (2×), and 15.144 Å. The orientation of the M(CO)3
98(2)
84(2)
99.53(8)
99.56(9)
89.53(6)
89.71(6)
89.87(6)
90.87(6)
1
groups with respect to the layers has no significant influ-
ence on the distances between the clusters. Irrespective of
their orientation the two different layers of clusters (I and
II), one of which is shown in Figure 4a, arrange in a cubic-
type packing as indicated in Figure 4b by the labels ABCA
perpendicular to the ab plane (not along c).
In compound 2, the distorted layers are packed pairwise
along the b direction of the unit cell. Within the AAЈ and
(
Mo–Pb6, Mo–Pb8) originate from the nonplanarity of the BBЈ layers (Figure 5) the M(CO) groups of two layers are
3
five coordinated Pb atoms.
oriented towards each other, leading to a larger distance of
Very recently, another compound of the composition 14.431 Å between these layers as compared to the AЈB and
K [K(2.2-crypt)] [Pb {Mo(CO) } ](en) (4) with Mo–Pb BЈA interlayer distance of 12.502 Å. Consequently, different
2
2
5
3 2
3
[
24]
and Pb–Pb bonds has been reported by our group.
structure of the [{(OC) Mo}Pb {Mo(CO) }] anion (Fig- ative orientation of the carbonyl groups of the Mo(CO)3
The intercluster distances of 16.617 and 14.308 Å occur. The rel-
4
–
3
5
3
ure 3b) contains a planar five-membered ring of lead atoms. unit might be the origin of the larger unit cell volume of 2
The Pb–Pb bond lengths between 3.014(1) and 3.065(1) Å if compared to 1.
3666
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3663–3669

4 9 3
Crystal Structures of [K(2.2.2-crypt)] [Pb Mo(CO) ]
FULL PAPER
Figure 5. (a) The hexagonal packing in the ac plane in the single
crystal of compound 2. (b) The stacking sequence of the layers
along the b axis in compound 2 (2.2.2-crypt units are not shown).
Figure 4. (a) The hexagonal packing in the ab plane in the single
crystal of compound 1. (b) The stacking sequence of the layers
along the c axis in compound 1 (2.2.2-crypt units are not shown).
5
ion [K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] (1) was isolated and
IR Spectra
4
9
3
characterized by single-crystal X-ray structure and IR
analyses. The carbonyl (CO) stretching vibrations ( ν˜ =
807, 1697 cm ) in the IR spectrum of compound 1 clearly
show the exclusive formation of the [(η -Pb )Mo(CO) ]
isomer. The [K(2.2.2-crypt)] [(η -Pb )Mo(CO) ] isomer (2),
which has been isolated for the first time as a pure product,
is formed together with its isomer 1 in the reaction of
Single crystals of 1 and the crude product were carefully
checked by solid-state IR analyses. The characteristic CO
–1
1
5
stretching vibrations of the η -isomer are found at 1809 and
5
4–
9
3
–
1
4
1
697 cm . None of the characteristic peaks of the η -iso-
4
4
9
3
–
1 [16]
mer ( ν˜ = 1813, 1736, and 1702 cm )
were detected
5
(Table 4). The carbonyl bands of the η -isomer are red-
4
shifted relative to those of the η -isomer. This red-shift has
[
Mo(CO) (Mes)] with K Pb under the same reaction con-
3 4 9
5
also been observed for the isomeric compounds [(η -Sn )-
9
ditions.
4
–
–1
4
4–
W(CO)3] ( ν˜ = 1805, 1701 cm ) and [(η -Sn )W(CO) ]
9
3
–
1
( ν˜ = 1822, 1711, 1701 cm ; see also Table 4).
As already mentioned above, several crystals of com-
Experimental Section
pound 1 were checked by X-ray diffraction and identified
5
The synthesis of compound 1 was carried out under argon in a
glove-box or in a Schlenk line. The IR spectra were recorded from
KBr pellets with a JASCO FT/IR-460 spectrometer. The X-ray
crystal data were collected with a Nonius Kappa CCD device at
the window of a rotating anode X-ray generator and processed with
as the η -isomer. The IR study gave further evidence that
the reaction of [Mo(CO) (MeCN) ] with K Pb yields ex-
3
3
4
9
clusively one isomer (1). Our attempts to obtain a 2 Pb
NMR spectrum of compound 1 were unsuccessful due to
its poor solubility in the usual solvents (en, DMF, THF,
DMSO, and toluene).
07
[25]
the SHELXS-97 and SHELXL-97 program packages. The crys-
tallographic data for the structures are summarized in Table 5.
CCDC-258685 (1) and -258686 (2) contain the supplementary crys-
tallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif. The elemental analyses were
Conclusions
The reaction of [Mo(CO) (MeCN) ] with K Pb in the carried out by the Microanalytical Laboratory at TU Munich. Tol-
3
3
4
9
presence of 2.2.2-crypt was investigated. A metalated Zintl uene (Merck) and en (Merck) were dried with K/CaH
2
(Fluka),
Eur. J. Inorg. Chem. 2005, 3663–3669
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3667

L. Yong, S. D. Hoffmann, T. F. Fässler
FULL PAPER
9
Table 4. The characteristic CO stretching vibrations in E Zintl complexes.
–
1
Complexes
ν
CO [cm ]
Ref.
4
[17]
[17]
[16]
[17]
[16]
[21]
[16]
[16]
[
[
[
[
[
[
K(2.2.2-crypt)]
K(2.2.2-crypt)]
K(2.2.2-crypt)]
K(2.2.2-crypt)]
K(2.2.2-crypt)]
K(2.2.2-crypt)]
4
4
4
4
4
4
[(η -Sn
9
9
9
9
9
)Cr(CO)
)Mo(CO)
)Mo(CO)
3
]
3
1822, 1705
1829, 1708
1830, 1718, 1703
1805, 1701
1822, 1711, 1701
1791, 1695, 1681
1813, 1736, 1702
1804, 1697, 1686
1809, 1697
4
[(η -Sn
]
]
4
[(η -Sn
3
]
]
5
[(η -Sn
)W(CO)
)W(CO)
3
4
[(η -Sn
3
4
[(η -Pb
9
)Cr(CO)
3
]
4
Mo(CO)
W(CO) (en)
K(2.2.2-crypt)]
3
(en)
2
[K(2.2.2-crypt)]
[(η -Pb
)Mo(CO)
{Mo(CO)
4
[(η -Pb
9
)Mo(CO)
3
]
4
3
2
[K(2.2.2-crypt)]
4
9
)W(CO)
3
]
5
[
K
4
[(η -Pb
[K(2.2-crypt)] [Pb
9
3
]
this work
[24]
2
2
5
3
}
2
](en)
3
1889, 1878, 1737
Table 5. Crystallographic data for compounds 1 and 2.
K(2.2.2-crypt)]
Mo
5
4
[
4
[(η -Pb
9
)Mo(CO)
3
]
[K(2.2.2-crypt)]
4
[(η -Pb
9
)Mo(CO)
3
]
Empirical formula
C
75
H
144
K
4
1
N
8
O27Pb
9
C
75
H
144
K
4
MoN
8
O
27Pb
9
–1
Formula mass [gmol ]
3707.03
173(2)
3707.03
120(2)
0.71073
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
γ [°]
0.71073
triclinic
monoclinic
P2 /n (no. 14)
¯
P1 (no.2)
1
15.4651(1)
16.6519(1)
25.5701(2)
79.265(1)
75.144(1)
62.842(1)
5644.9(1)
2
15.066(1)
53.866(1)
15.779(1)
90
115.473(1)
90
11560.7(3)
4
2.130
Volume [ų]
Z
–3
ρ
calcd. [gcm ]
2.181
13.686
–1
µ [mm ]
13.366
6888
F(000)
3444
Crystal size [mm]
θ range [°]
Index ranges
0.40×0.40×0.20
1.38 to 25.37
0 Յ h Յ 18
0.20×0.10×0.05
4.09 to 20.85
–15 Յ h Յ 13
0 Յ k Յ 37
0 Յ l Յ 15
49478
–
–
17 Յ k Յ 20
29 Յ l Յ 30
Reflections collected
Independent reflections
Goodness-of-fit on F²
Final R indices[I Ͼ 2σ(I)]
R indices (all data)
126980
20659 (Rint = 0.084)
1.067
9540 (Rint = 0.180)
1.021
R
R
1
= 0.058, wR
= 0.082, wR
2
= 0.137
= 0.148
R
R
1
= 0.103, wR
= 0.148, wR
2
= 0.257
= 0.287
1
2
1
2
–3
Largest peak/hole [eÅ ]
3.107/–2.146
8.597/–3.409
freshly distilled, and degassed. The binary phase of the formal com-
position “K Pb ” was prepared by a high-temperature reaction
350 °C) from the elements K and Pb in the ratio of 4:9. Tricarbon-
yl(mesitylene)molybdenum and tris(acetonitrile)tricarbonylmolyb-
denum were prepared by heating Mo(CO) (Alfa Inorganics) in an
was carried out under the same reaction conditions with the same
workup procedure.
4
9
(
Acknowledgments
6
excess of mesitylene or MeCN under reflux under nitrogen accord-
ing to the reported methods.[
22]
This work was supported by the Deutsche Forschungsgemeinschaft
(
SPP 1072). We thank Dr. Klaus Ruhland for his kind assistance
K
4
Pb
were dissolved in en (ca. 1 mL) and stirred for 5 min. A yellow
solution of [Mo(CO) (MeCN) ] (16 mg, 0.051 mmol) in toluene
ca. 2 mL) was then added to the green solution of K Pb . The
9
(100 mg, 0.049 mmol) and 2.2.2-crypt (74 mg, 0.2 mmol)
207
with the
Pb NMR study and Dr. Annette Schier for checking
the manuscript.
3
3
(
4
9
[
1] a) A. Schnepf, Angew. Chem. Int. Ed. 2003, 42, 2624–2625; b)
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8 h, dark-brown crystals of [K(2.2.2-crypt)]
cipitated (48 mg, ca. 45% with respect to K Pb
sis of the products from this reaction (3707.03): calcd. C 24.30, H
.92, N 3.02; found C 24.49, H 3.60, N 3.18. The reaction of K Pb
100 mg, 0.049 mmol) with [Mo(CO) (Mes)] (15 mg, 0.049 mmol)
4
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(
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3668
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3663–3669

4 9 3
Crystal Structures of [K(2.2.2-crypt)] [Pb Mo(CO) ]
FULL PAPER
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Received: January 20, 2005
Published Online: June 21, 2005
6242–6247.
Eur. J. Inorg. Chem. 2005, 3663–3669
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3669