Novel rearrangement reactions. 5. Thermal rearrangement of digermyl-bridged biscyclopentadienyl diiron complexes (Me2GeGeMe2)[(η5-C5R 4)Fe(CO)]2(μ-CO)2 (R = H and Me)

Article abstract of DOI:10.1021/om980464u

Complexes (Me₂GeGeMe₂)[(η⁵-C₅R ₄)Fe(CO)]₂(μ-CO)₂ (R = H, 1; Me, 3) 1 and 3, prepared by the reaction of C₅R₄HMe₂GeGeMe₂C₅R ₄H with Fe(CO)₅ in refluxing xylene, underwent a novel thermal reaction between their Ge-Ge and Fe-Fe bonds, forming corresponding rearrangement products with new cyclic structures, [Me₂Ge(η⁵-C₅R₄)Fe(CO) ₂]₂ (R = H, 2; Me 4). Compared with the case of silicon, the weaker Ge-Ge bond resulted in an easier rearrangement reaction. Reactions of 1 with iodine and sodium amalgam were examined. Molecular structures of 1, 2, 3, and 4 were determined by X-ray diffraction.

Full text of DOI:10.1021/om980464u

5406
Organometallics 1998, 17, 5406-5410
Novel Rea r r a n gem en t Rea ction s. 5. Th er m a l
Rea r r a n gem en t of Diger m yl-Br id ged
Biscyclop en ta d ien yl Diir on Com p lexes
(Me2GeGeMe2)[(η5-C5R4)F e(CO)]2(µ-CO)2 (R ) H a n d Me)
Wenhua Xie, Baiquan Wang, Xuliang Dai, Shansheng Xu, and Xiuzhong Zhou*
Department of Chemistry, Nankai University, Tianjin 300071, People’s Republic of China
Received J une 5, 1998
Complexes (Me2GeGeMe2)[(η5-C5R4)Fe(CO)]2(µ-CO)2 (R ) H, 1; Me, 3) 1 and 3, prepared
by the reaction of C5R4HMe2GeGeMe2C5R4H with Fe(CO)5 in refluxing xylene, underwent a
novel thermal reaction between their Ge-Ge and Fe-Fe bonds, forming corresponding
rearrangement products with new cyclic structures, [Me2Ge(η5-C5R4)Fe(CO)2]2 (R ) H, 2;
Me 4). Compared with the case of silicon, the weaker Ge-Ge bond resulted in an easier
rearrangement reaction. Reactions of 1 with iodine and sodium amalgam were examined.
Molecular structures of 1, 2, 3, and 4 were determined by X-ray diffraction.
In tr od u ction
tions.5 The similarity between silicon and germanium
led us to synthesize the related germyl-bridged ana-
logues and to examine the corresponding rearrangement
reaction between Ge-Ge and Fe-Fe bonds.
Considerable attention has been focused on the
synthesis and chemical behavior of a variety of bridged
binuclear metal-metal-bonded transition-metal com-
plexes.1 These systems are suitable for studying inter-
actions between two metal reaction sites that are in
close proximity. In particular, we have been interested
in bridged biscyclopentadienyl tetracarbonyl diiron
complexes in which two cyclopentadienyl ligands are
linked together by certain alkyl or silyl groups.2 Com-
pared to their nonbridged analogues, these complexes
exhibit unique characteristics in both their structures
and reactivity.3
Resu lts a n d Discu ssion
Syn th esis of (Me2GeGeMe2)[(η5-C5R4)F e(CO)]2(µ-
CO)2 a n d Its Rea r r a n gem en t Rea ction . 1,2-Bis-
(cyclopentadienyl)tetramethyldigermane, C5H5Me2Ge-
GeMe2C5H5, which was prepared by reaction of 1,2-
dichlorotetramethyldigermane, ClMe2GeGeMe2Cl, and
cyclopentadienyllithium, was treated with Fe(CO)5 in
xylene under reflux for 10 h. After workup, preparative
thin-layer chromatography (TLC) afforded purple crys-
tals of 1 in 12% yield, as well as a yellow product, which
was later confirmed to have the structure of 2 (Scheme
2). To illuminate the relationship between 1 and 2, a
xylene solution of isolated pure 1 was refluxed for 6 h.
It was found that, despite some decomposition, 1 was
entirely converted into 2. This suggested that 2 was
formed via a thermal rearrangement reaction between
the Ge-Ge and Fe-Fe bonds of 1, similar to its sila-
bridged analogue.4
It is worth noting that even at a considerably lower
temperature (110 °C for 24 h in refluxing toluene), the
reaction still proceeded readily. In contrast, there was
hardly any rearrangement observed for the silicon
analogue under the same conditions. Apparently, the
weakness of the Ge-Ge bond (relative to the Si-Si
bond) facilitated the rearrangement.
We recently reported a novel rearrangement of the
Si-Si and Fe-Fe bonds in a binuclear iron complex
(Me2SiSiMe2)[(η5-C5H4)Fe(CO)]2(µ-CO)2 (Scheme 1).4 An
alternative mechanism was subsequently proposed based
on detailed investigation of the rearrangement ste-
reospecificity, reaction intermediate, and crossover reac-
* Corresponding author. Fax: 0086-22-23502458. Tel: 0086-22-
23502610. E-mail: zhouxz@public1.tpt.tj.cn.
(1) (a) Maitlis, P. M. J . Organomet. Chem. 1995, 500, 239. (b)
Atwood, C. G.; Geiger, W. E.; Rheingold, A. L. J . Am. Chem. Soc. 1993,
115, 5310. (c) Abriel, W.; Baum, G.; Heck, J .; Kriebisch, K. A. Chem.
Ber. 1990, 123, 1767. (d) Abriel, W.; Heck, J . J . Organomet. Chem.
1986, 302, 363. (e) Herberhold, M.; Biersack, M. J . Organomet. Chem.
1993, 444, C41. (f) Bryndza, H. E.; Bergman, R. G. J . Am. Chem. Soc.
1979, 101, 4766. (g) de Azevedo, C. G.; Boese, R.; Newman, D. A.;
Vollhardt, K. P. C. Organometallics 1995, 14, 4980. (h) Eilbracht, P.;
Dahler, P.; Tiedtke, G. J . Organomet. Chem. 1980, 185, C25.
(2) (a) Weiss, E.; Hubel, W. Chem. Ber. 1962, 95, 1186. (b) Cardle,
P. M. Chem. Commun. 1969, 1310. (c) Weaver, J .; Woodward, P. J .
Chem. Soc., Dalton Trans. 1973, 1439. (d) J anda, K. D.; McConnell,
W. W.; Nelson, G. O.; Wright, M. E. J . Organomet. Chem. 1983, 259,
139. (e) Moran, M.; Cuadrado, I.; Masaguer, J . R. J . Chem. Soc., Dalton
Trans. 1988, 833. (f) Siemeling, U.; J utzi, P.; Neumann, B.; Stammler,
H. G.; Hursthouse, M. B. Organometallics 1992, 11, 1328. (g) Cox, M.
G.; Manning, A. R. J . Organomet. Chem. 1994, 469, 189. (h) van den
Berg, W.; Boot, C. E.; van der Linden, J . G. M.; Bosman, W. P.; Smits,
J . M. M.; Beurskens, P. T.; Heck, J . Inorg. Chim. Acta 1994, 216, 1.
(3) (a) Wegner, P. A.; Uski, V. A.; Kiester, R. P. J . Am. Chem. Soc.
1977, 99, 4846. (b) Xie, W.; Zhou, X.; Xu, S.; Wang, H.; Wang, R. Acta
Chim. Sin. 1995, 53, 1131.
Similarly, when the tetramethyl-substituted ligand
C5Me4HMe2GeGeMe2C5Me4H was treated with Fe(CO)5
in refluxing xylene for 8 h, complex 3 was obtained in
27% yield, and its rearrangement product 4 in 12%
yield. A small amount of degermylation product [η5-
C5HMe4Fe(CO)]2(µ-CO)2 was also isolated at the same
(5) (a) Zhou, X.; Zhang, Y.; Xie, W.; Xu, S.; Sun, J . Organometallics
1997, 16, 3474. (b) Wang, B.; Zhang, Y.; Xu, S.; Zhou, X. Organome-
tallics 1997, 16, 4620.
(4) Sun, H.; Xu, S.; Zhou, X.; Wang, H.; Wang, R.; Yao, X. J .
Organomet. Chem. 1993, 444, C41.
10.1021/om980464u CCC: $15.00 © 1998 American Chemical Society
Publication on Web 11/04/1998

Novel Rearrangement Reactions
Organometallics, Vol. 17, No. 24, 1998 5407
Sch em e 1
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 1 a n d 3
Sch em e 2
1
3
Fe-Fe′
2.544(3)
2.408(2)
2.009(6)
2.141(5)
2.581(5)
2.390(4)
1.974(16)
2.129(16)
Ge-Ge′
Ge-C(11)
Fe-C(11)
Fe′-Fe-C(11)
Ge′-Ge-C(11)
Ge-C(11)-Fe
110.3(5)
113.8(4)
128.6(7)
93.99
109.6(4)
113.6(5)
134.8(8)
107.12
a
PL-PL′
a
PL ) the plane of the Cp ring.
F igu r e 1. Molecular structure of (Me2GeGeMe2)[(η5-C5H4)
Fe(CO)]2(µ-CO)2 (1). Hydrogen atoms are omitted for clar-
ity.
F igu r e 2. Molecular structure of [Me2Ge(η5-C5H4)Fe-
(CO)2]2 (2). Hydrogen atoms are omitted for clarity.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 2
time. A sample of pure complex 3 was then refluxed in
xylene for 10 h. 4 was isolated in 32% yield ac-
companied by some decomposition. This was very
different from the Si-Si bridged analogue, which un-
derwent rearrangement with great difficulty, affording
the rearrangement product in very low yield.6
A significant difference between 1 and 2 or 3 and 4
was presented in their IR spectra. While 1 and 3 both
have absorptions for terminal and bridged carbonyl
groups, 2 and 4, in accordance with their structures as
determined by X-ray diffraction analysis, show only
terminal CO ligands. The molecular structures of all
complexes were confirmed by single-crystal X-ray dif-
fraction.
Molecu la r Str u ctu r es of 1, 2, 3, a n d 4. The
molecular structure of 1 is presented in Figure 1. Table
1 provides the selected bond distances and angles. The
molecule of 1 has mirror symmetry. This is different
from its silicon analogue, which was found to be unsym-
metrical.6 In 1, two germanium atoms and two iron
Bond Distances
Fe-Ge
Ge-C(15a)
2.379(2)
1.955(6)
Fe-C(15)
2.123(5)
Bond Angles
Ge-Fe-C(15)
Fe-Ge-C(15a)
100.1(2)
112.1(2)
C(1)-Fe-C(2)
C(16)-Ge-C(17)
91.3(3)
106.3(3)
atoms are planar. The six-membered ring formed by
germanium, iron, and the bridgehead carbon atoms of
the cyclopentadienyl rings takes a standard boat con-
formation, which results in certain molecular strain.
The Fe-Fe distance [2.544(3) Å] is longer than that in
its silicon analogue [2.526(2) Å]. The Ge-Ge bond
length is 2.408(2) Å, and the dihedral angle between
the two cyclopentadienyl ring planes is 93.99°.
The molecular structure of 2 is illustrated in Figure
2. Selected bond distances and angles are listed in
Table 2. The molecule of 2 consists of two [Me2Ge(η5-
C5H4)Fe(CO)2] moieties linked to each other by two Ge-
Fe bonds. Like many analogues,4,6,7 2 has Ci symmetry.
The six-membered ring Fe-Ge-C(15a)-Fe(a)-Ge(a)-
(6) Zhou, X.; Zhong, X.; Zhang, Y.; Xu, S. J . Organomet. Chem. 1997,
545-546, 435.

5408 Organometallics, Vol. 17, No. 24, 1998
Xie et al.
A
B
F igu r e 3. Molecular structure of (Me2GeGeMe2)[(η5-C5-
Me4)Fe(CO)]2(µ-CO)2 (3).
C(15), constituting its molecular framework, adopts
precisely a stable chair conformation. The Fe-Ge
distance [2.379(2) Å] is slightly longer than the Fe-Si
bond [2.315(2) Å] in its silicon analogue. It is notewor-
thy that whereas the six-membered rings in related Fe-
Fe complexes (for both silicon and germanium ana-
logues) may be in twisted boat or boat conformation,
the corresponding rings in the rearrangement products
always take a standard chair conformation,4-7 a struc-
tural characteristic of the products. It appears that
such chair conformations, which are highly symmetrical,
are preferred in energy, while the molecular strain in
the substrates is likely to be the driving force of the
rearrangement reaction.
The molecular structure of 3 is presented in Figure
3. Table 1 provides selected bond distances and angles.
Similar to its silicon analogue, the molecule of 3 has C2
symmetry. The corresponding six-membered ring also
takes a twist boat conformation. As in its silicon
analogue,6 the Fe-Fe distance [2.581(5) Å] is longer
than that in the parent complex 1 [2.544(3) Å], while
the Ge-Ge bond length [2.390(4) Å] is slightly shorter
than in 1 [2.408(2) Å]. This may be attributed to the
steric effect of the crowded methyl groups. The steric
repulsion results in a slight stretch of the Fe-Fe bond
and a compression of the Si-Si bond, to reduce unfavor-
able nonbonded interactions. The dihedral angle
[107.12°] between the two cyclopentadienyl ring planes
is much larger than in 1 [93.99°]. The Ge atoms deviate
from the linked cyclopentadienyl rings by 0.3857 Å.
The molecular structure of 4 is illustrated in Figure
4. Selected bond distances and angles are listed in
Table 3. There are two independent molecules with the
ratio of 1/2 (A/B) in the unit cell: one (A) being unsym-
metrical, and the other (B) having Ci symmetry. The
dihedral angle between the two Cp rings is 2.29° for A,
while the two Cp planes are parallel to each other for
B. Like complex 2, B has Ci symmetry, and the
F igu r e 4. Molecular structure of [Me2Ge(η5-C5Me4)Fe-
(CO)2]2 (4), showing labeling scheme for the two indepent
molecules present as a ratio of 1/2 (A/B) in the crystal
structure.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 4
Bond Distances
Fe(1)-Ge(2)
Fe(2)-Ge(1)
Fe(3)-Ge(3)
Ge(1)-C(11)
Ge(3)-C(31a)
2.403(1)
2.401(1)
2.395(1)
1.988(8)
1.986(7)
Fe(1)-C(11)
Fe(2)-C(21)
Fe(3)-C(31)
Ge(2)-C(21)
2.109(7)
2.128(6)
2.118(7)
1.992(7)
Bond Angles
Ge(2)-Fe(1)-C(11)
Ge(1)-Fe(2)-C(21)
Ge(3)-Fe(3)-C(31)
Fe(2)-Ge(1)-C(11)
89.8(2)
89.0(2)
99.0(2)
Fe(1)-C(11)-Ge(1)
137.1(3)
137.1(3)
Fe(2)-C(21)-Ge(2)
Fe(3)-C(31)-Ge(3a) 134.5(3)
120.0(2) Fe(1)-Ge(2)-C(21)
120.5(2)
Fe(3)-Ge(3)-C(31a) 119.1(2)
corresponding six-membered ring adopts a standard
chair conformation. The Fe-Ge distance [2.401(1) Å for
A; 2.395(1) Å for B] is slightly longer than those in 2
(2.379(2) Å), presumably due to the repulsion of methyl
groups.
Rea ctivity of 1. Experiments were conducted to
examine if there were any special features about the
reactivity of 1, the first example of a dinuclear Fe-Fe
complex containing a Ge-Ge bond, arising from the
introduction of the germyl bridge. Reaction of 1 with
iodine in CHCl3 gave a normal Fe-Fe cleaved product,
5 (Scheme 3). No other product was detected. This
indicated that although the Ge-Ge bond is liable to
cleavage by halogens (Cl2, and Br2 in some instances),
and although it seemed somehow activated in 1 (in that
(7) (a) Sharma, S.; Cervantes, J .; Mata-Mata, J . L.; Brun, M. C.;
Cervantes-Lee F.; Pannell, K. H. Organometallics 1995, 14, 4269. (b)
Zhang, Y.; Xu, S.; Zhou, X. Organometallics 1997, 16, 6017.

Novel Rearrangement Reactions
Organometallics, Vol. 17, No. 24, 1998 5409
Ta ble 4. Su m m a r y of X-r a y Diffr a ction Da ta
1
2
3
4
formula
fw
space group
cryst syst
Z
C
18H20Fe2Ge2O4
C18H20Fe2Ge2O4
557.23
P21/n
monoclinic
2
C26H36Fe2Ge2O4
669.45
P-4
tetragonal
2
C26H36Fe2Ge2O4
669.45
P-1
triclinic
3
557.26
P21/m
monoclinic
2
a (Å)
b (Å)
c (Å)
7.095(5)
15.455(3)
9.126(3)
9.046(1)
10.606(2)
10.704(3)
11.073(2)
11.073(2)
11.243(2)
8.821(2)
9.610(2)
26.328(5)
81.02(3)
87.29(3)
69.78(3)
2068(1)
1.612
R (deg)
â (deg)
γ (deg)
volume (Å3)
92.35(4)
96.57(2)
1000(1)
1.78
1020.1(6)
1.864
1738.5(9)
1.613
d
calc (g cm-1
)
crystal size (mm)
0.2 × 0.3 × 0.3
MoKR(0.71073)
43.77
ω/2θ
46.0
1543
981
136
0.045
0.2 × 0.3 × 0.2
MoKR(0.71073)
42.94
ω/2θ
46.0
1598
1157
118
0.038
0.2 × 0.3 × 0.4
MoKR(0.71073)
31.92
ω/2θ
46.0
2154
1697
154
0.10
0.1 × 0.2 × 0.5
MoKR(0.71073)
31.91
ω/2θ
46.0
5898
3838
460
0.046
radiation (Å3)
µ (cm-1
)
data collection method
max 2θ (deg)
total no. of observns
no. of unique data, I > 3σ(I)
final no. of variables
Ra
b
Rw
0.049
0.045
0.12
0.050
goodness-of-fit
2.58
2.033
2.27
0.88
a
b
2 1/2
∑||Fo - Fc||/∑|Fo|. [∑w(|Fo| - |Fc|)2/∑wFo
] .
filtered through a short Al2O3 column (5 × 3 cm). Removal of
solvent yielded 1.9 g of a pale yellow oil. This was used
without further purification. 1H NMR (90 MHz, CDCl3): δ
0.20(s, 12H, 2GeMe2), 2.90(s, 2H, R-H), 5.80-6.80(m, 8H,
2C5H4).
Sch em e 3
P r ep a r a t ion of (Me2GeGeMe2)[(η5-C5H 4)F e(CO)]2(µ-
CO)2 (1) a n d [Me2Ge(η5-C5H4)F e(CO)2]2 (2). A 1.9 g (5.7
mmol) sample of C5H5Me2GeGeMe2C5H5 and 2.4 mL of Fe-
(CO)5 were heated in 50 mL of xylene under reflux for 10 h.
After removal of excess of Fe(CO)5 and solvent under vacuum,
preparative TLC afforded first a yellow band, then a red one,
from which yellow crystals of 2 (0.24 g, 10%) and dark red
crystals of 1 (0.29 g, 12%) were obtained, respectively. For 1:
Anal. Calcd for C18H20Fe2Ge2O4: C, 38.80; H, 3.62. Found:
C, 38.45; H, 3.50. IR (νCO, cm-1): 1753.5, 1794.5, 1942.2,
1975.0. 1H NMR (90 MHz, CDCl3): δ 0.48(s, 12H, 2GeMe2),
4.36(s, 4H, 2C5H2), 5.32(s, 4H, 2C5H2). For 2: Anal. Calcd
for C18H20Fe2Ge2O4: C, 38.80; H, 3.62. Found: C, 38.61; H,
3.55. IR (νCO, cm-1): 1934.0, 1975.0. 1H NMR (200 MHz,
CDCl3): δ 0.56(s, 12H, 2GeMe2), 4.96(d, 8H, 2C5H4).
it reacted with the Fe-Fe bond), it remained inactive
as usual to iodine. Treatment of 1 with sodium amal-
gam in THF showed that the Ge-Ge bridge did not
affect either the usual reduction of the Fe-Fe bond or
the subsequent nucleophilic reaction of the anion.
Rea r r a n gem en t Rea ction of Com p lex 1. A 0.15 g
sample of 1 was heated in refluxing xylene (20 mL) for 6 h.
The originally dark red solution turned orange-yellow. After
removal of solvent, the residue was extracted with CH2Cl2 and
filtered through a short Al2O3 column (7 × 3 cm). From the
filtrate, 0.1 g (67%) of yellow crystals of 2 was obtained.
Exp er im en ta l Section
Gen er a l P r oced u r es. Schlenk and vacuum line tech-
niques were employed for all manipulations of air- and
moisture-sensitive compounds. Reaction solvents were dis-
tilled from appropriate drying agents under argon before use.
Tetrahydrofuran, heptane, and xylene were distilled from
sodium/benzophenone ketyl and purged with argon prior to
use. 1H NMR spectra were recorded on a J EOL FX-90Q or
BRUKER AC-P200 spectrometer, whereas infrared spectra
were recorded on a Nicolet 5DX FT-IR spectrometer as a KBr
disk. Elemental analyses were performed by a Perkin-Elmer
240C analyzer. 1,2-Dichlorotetramethyldigermane was pre-
pared from GeMe4 by literature methods.8
P r ep a r a tion of C5H5Me2GeGeMe2C5H5. A solution of
ClMe2GeGeMe2Cl (1.8 g, 6.5 mmol) in 10 mL of THF was added
to 13 mmol of cyclopentadienyllithium in 30 mL of THF. After
5 h of stirring at room temperature, solvent was removed
under vacuum. The residue was extracted with CH2Cl2 and
P r ep a r a tion of C5Me4HMe2GeGeMe2C5Me4H. A solu-
tion of ClMe2GeGeMe2Cl (2.25 g, 8.2 mmol) in 20 mL of THF
was added to 16.4 mmol of tetramethylcyclopentadienyllithium
in 30 mL of THF. After 12 h of stirring at room temperature,
30 mL of water was added. The aqueous layer was separated
and extracted twice with 20 mL of ether. The organic and
ether extracts were combined and dried over anhydrous
sodium sulfate. The solvents were removed under reduced
pressure.The residue was recrystallized from pentane and
afforded 1.2 g (33%) of white crystals. 1H NMR (90 MHz,
CDCl3): δ 0.16(s, 12H, 2GeMe2), 1.72(s, 12H, 2C5Me2), 1.76(s,
12H, 2C5Me2), 2.90(m, 2H, 2R-H).
P r ep a r a tion of (Me2GeGeMe2)[(η5-C5Me4)F e(CO)]2(µ-
CO)2 (3) a n d [Me2Ge(η5-C5Me4)F e(CO)2]2 (4). A 1.1 g (2.5
mmol) sample of C5Me4HMe2GeGeMe2C5Me4H and 1.5 mL of
Fe(CO)5 were heated in 50 mL of xylene under reflux for 8 h.
After removal of excess of Fe(CO)5 and solvent under vacuum,
preparative TLC afforded first a yellow band, then two red
(8) (a) Abel, E. W.; Armitage, D. A.; Brady, D. B. J . Organomet.
Chem. 1965, 5, 130. (b) Triplete, K.; Curtis, M. D. J . Organomet. Chem.
1976, 107, 23.

5410 Organometallics, Vol. 17, No. 24, 1998
Xie et al.
bands, from which yellow crystals of 4 (0.19 g, 12%), dark red
crystals of 3 (0.46 g, 27%), and dark red crystals of [(η5-C5-
Me4H)Fe(CO)]2(µ-CO)2 (55 mg) were obtained. For 3: Anal.
Calcd for C26H36Fe2Ge2O4: C, 46.65; H, 5.42. Found: C, 46.62;
H, 5.54. IR (νCO, cm-1): 1748.2, 1925.2, 1973.1. 1H NMR (200
MHz, CDCl3): δ 0.37(s, 12H, 2GeMe2), 1.84(s, 12H, 2C5Me2),
1.95(s, 12H, 2C5Me2). For 4: Anal. Calcd for C26H36Fe2-
[(η5-C5H4)Fe(CO)2C(O)Ph]2 (7) were isolated, as yellow crystals
from the respective reaction mixtures by column chromatog-
raphy. For 6: Anal. Calcd for C22H26 Fe2Ge2O6: C, 41.07; H,
4.07. Found: C, 40.85; H, 4.22. IR (νCO, cm-1): 2010.1, 1952.6.
1H NMR (90 MHz, CDCl3): δ 0.48(s, 12H, 2GeMe2), 4.69(s,
4H, 2C5H2), 5.00(s, 4H, 2C5H2). For 7: Anal. Calcd for C32H30
Fe2Ge2O6: C, 50.08; H, 3.94. Found: C, 50.20; H, 4.12. IR
(νCO, cm-1): 2016.0, 1955.4. 1H NMR (90 MHz, CDCl3): δ 0.51-
(s, 12H, 2GeMe2), 4.88(s, 4H, 2C5H2), 5.08(s, 4H, 2C5H2).
Molecu la r Str u ctu r e Deter m in a tion . Crystals suitable
for X-ray diffraction were obtained from hexane/dichlo-
romethane solutions. All data sets were collected on an Enraf-
Nonius CAD-4 diffractometer with graphite-monochromated
Mo KR radiation. Empirical absorption corrections using the
program DIFBAS were applied to intensity data. All calcula-
tions were performed on a PDP11/44 computer using the SDP-
PLUS program system. The structures were solved by a direct
phase determination method and expanded using Fourier
techniques. The non-hydrogen atoms were refined anisotro-
pically. Hydrogen atoms were refined isotropically. Neutral
atom scattering factors were taken from the tabulation of
Cromer and Waber.10 Selected bond distances and angles for
1, 2, 3, and 4 are given in Tables 1, 2, and 3, respectively. A
summary of the crystallographic results is presented in Table
4.
Ge2O4: C, 46.65; H, 5.42. Found: C, 46.63; H, 5.41. IR (νCO
,
cm-1): 1932.0, 1968.6. 1H NMR (200 MHz, CDCl3): δ 0.55(s,
12H, 2GeMe2), 1.88(s, 12H, 2C5Me2), 1.96(s, 12H, 2C5Me2). For
[(η5-C5Me4H)Fe(CO)]2(µ-CO)2:9 Anal. Calcd for C22H26Fe2O4:
C, 56.69; H, 5.62. Found: C, 57.01; H, 5.80. IR (νCO, cm-1):
1734.2, 1753.5, 1942.2, 1975.0. 1H NMR (90 MHz, CDCl3): δ
1.69(s, 12H, 2C5Me2), 1.72(s, 12H, 2C5Me2), 3.83(s, 2H, Cp-
H).9
Th e Rea r r a n gem en t Rea ction of Com p lex 3. Similar
to the rearrangement of 1, 0.28 g of 3 was refluxed in 30 mL
of xylene for 10 h; 0.09 g (32%) of 4 was obtained.
Rea ction of 1 w ith I2. A 0.17 g (0.30 mmol) sample of 1
and 0.08 g (0.30 mmol) of I2 were stirred in CHCl3 (15 mL) for
3 h. Excess I2 was removed by washing with a Na2S2O3
solution. The organic layer was dried and chromatographed
on an Al2O3 column (220 cm, CH2Cl2) to give dark brown
crystals of (Me2GeGeMe2)[(η5-C5 H4 )Fe(CO)2 I]2 (5) (0.13 g,
53%). Anal. Calcd. For C18H20Fe2Ge2I2O4: C, 26.60; H, 2.49.
1
Found: C, 26.64; H, 2.42. IR (νCO, cm-1): 2018.8, 1976.4. H
Ack n ow led gm en t. This work was financially sup-
ported by the National Science Foundation of China.
NMR (90 MHz, CDCl3): δ 0.61(s, 12H, 2GeMe2), 4.81(m, 4H,
2C5H2), 5.02(m, 4H, 2C5H2).
Rea ction of 1 w ith Na /Hg. A 0.33 g (0.60 mmol) sample
of 1 was treated with an excess of 1% sodium amalgam in THF.
The dark red color of the solution changed to yellow-brown
within 20 min. After 1 h, the resulting solution was divided
into two equal portions, which were treated, respectively, with
acetyl chloride (0.8 mmol) and benzoyl chloride (0.8 mmol).
After 3 h of stirring, 0.09 g (45%) of (Me2GeGeMe2)[(η5-
C5H4)Fe(CO)2C(O)Me]2 (6) and 0.12 g (52%) of (Me2GeGeMe2)-
Su p p or tin g In for m a tion Ava ila ble: Supporting Infor-
mation Available: Tables of final positional and thermal
parameters of the non-hydrogen atoms, general temperature
factors, calculated hydrogen atom positions, and bond dis-
tances and angles for 1, 2, 3, and 4 (36 pages). Ordering
information is given on any current masthead page.
OM980464U
(10) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
(9) Xu, S.; Zhong, X.; Zhou, X. Nankai Daxue Xuebao 1996, 29 (3),
104-6 (in Chinese).