Reactivity of pyridyl-1-azaallyl germanium(I) dimer: Synthesis of a digermahydrazine derivative and an iron-coordinated germanium(I) dimer

Article abstract of DOI:10.1021/om4009839

Reactivity of the pyridyl-1-azaallyl germanium(I) dimer LGeGeL (2; L = N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)) has been investigated. Treatment of germanium(I) dimer 2 with 1 equiv of azobenzene afforded the pyridyl-1-azaallyl digermahydrazine derivative [LGeNPh]₂ (3). The reaction of 2 with 1 and 2 equiv of diiron nonacarbonyl, Fe ₂(CO)₉, afforded the novel unsymmetric germanium(I) complex [LGeGe(Fe(CO)₄)L] (4) and the diiron Lewis acid-base adduct [LGe(Fe(CO)₄)]₂ (5). The solid-state structure of 4 reveals that the two germanium(I) centers within the same molecule have different coordinating geometries. Compound 4 can also be prepared by the facile reaction of the pyridyl-1-azaallyl germanium(II) chloride LGeCl (1) with Collman's reagent, Na₂Fe(CO)₄.

Full text of DOI:10.1021/om4009839

Article
pubs.acs.org/Organometallics
Reactivity of Pyridyl-1-azaallyl Germanium(I) Dimer: Synthesis of a
Digermahydrazine Derivative and an Iron-Coordinated Germanium(I)
Dimer
Wing-Por Leung,* Wang-Kin Chiu, and Thomas C. W. Mak
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
S
* Supporting Information
ABSTRACT: Reactivity of the pyridyl-1-azaallyl germanium(I) dimer
LGeGeL (2; L = N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)) has been
investigated. Treatment of germanium(I) dimer 2 with 1 equiv of
azobenzene afforded the pyridyl-1-azaallyl digermahydrazine derivative
[LGeNPh]2 (3). The reaction of 2 with 1 and 2 equiv of diiron
nonacarbonyl, Fe2(CO)9, afforded the novel unsymmetric germanium(I)
complex [LGeGe(Fe(CO)4)L] (4) and the diiron Lewis acid−base adduct
[LGe(Fe(CO)4)]2 (5). The solid-state structure of 4 reveals that the two
germanium(I) centers within the same molecule have different
coordinating geometries. Compound 4 can also be prepared by the facile
reaction of the pyridyl-1-azaallyl germanium(II) chloride LGeCl (1) with
Collman’s reagent, Na2Fe(CO)4.
Our group has reported the synthesis of the chlorogermylene
INTRODUCTION
■
1 (Figure 1) supported by a pyridyl-1-azaallyl ligand,10 and its
The chemistry of the heavier group 14 alkyne analogues (or
ditetrelynes) REER (E = Si, Ge, Sn, Pb; R = bulky terphenyl,
silyl, aryl substituents) has attracted much attention in the past
two decades.1 In 2000, Power and co-workers reported the first
diplumbyne analogue, RPbPbR, with a trans-bent structure.2
Subsequently, they also isolated the first stable digermyne3 and
distannyne.4 The series of alkyne analogues was completed
when Sekiguchi reported the structural characterization of a
stable disilyne in 2004.5 Furthermore, Jones and co-workers
have reported the isolation of the first amido-digermyne, which
possesses a short Ge−Ge multiple bond.1n Recently, the
chemistry of low-valent group 14 elements has extended to a
series of group 14 element(I) dimers6 following the pioneering
result reported by Jones in 2006.7 These group 14 metal(I)
dimers, comprising a metal−metal single bond and a lone pair
of electrons on each metal atom, can be considered as
intramolecular base-stabilized examples of the doubly or triply
bonded heavier group 14 alkyne analogues. The chemistry of
the silicon analogue has been extensively explored by Roesky
and co-workers.8 Furthermore, preliminary reactivity studies of
the intramolecularly donor-stabilized germanium(I) dimers
have been reported6e,g,9 in which the digermylene nature of
these species is demonstrated. For example, Roesky and co-
workers have communicated the reactivity of a gauche-bent
germanium(I) dimer with 2 equiv of diiron nonacarbonyl to
yield a unique diiron complex that employs both of the
germanium(I) centers as Lewis bases.9a Recently, So and co-
workers have described the reduction chemistry of germanium-
(I) dimers supported by 2,6-diiminophenyl and 2-imino-5,6-
methylenedioxylphenyl ligands.6g
Figure 1. Pyridyl-1-azaallyl germanium(II) chloride 1.
reactivity has been explored.11 Recently, we have also carried
out investigations on its reduction chemistry and communi-
cated the synthesis of the pyridyl-1-azaallyl germanium(I)
dimer 2, which adopts a trans-bent geometry.6e In view of the
reactivity of the gauche-bent germanium(I) dimer recently
reported by Roesky,9a we intended to carry out investigations
to compare the reactivity between germanium(I) dimers
adopting a trans-bent and a gauche-bent geometry. In addition,
the reaction of germanium(I) dimer with Fe2(CO)9 to give a
Received: October 8, 2013
Published: December 19, 2013
© 2013 American Chemical Society
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Scheme 1. Synthesis of 3−5
novel germanium(I) complex with one iron-coordinated
germanium center is also described.
tion numbers at the two germanium(I) centers. In compound
4, one of the germanium(I) centers coordinates to a Fe(CO)4
moiety. A tin(I) dimer with two differently coordinated tin
atoms (one is three-coordinated and the other is four-
coordinated) was recently reported by Roesky,6h while Driess
has documented the synthesis of a unsymmetric digermylene
supported by two different ligands.6d The reaction of
germanium(I) dimer 2 with Fe2(CO)9 differs from a previous
reaction with azobenzene, where cleavage of the Ge(I)−Ge(I)
interaction was observed.
RESULTS AND DISCUSSION
■
Synthesis of [PhNGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-
2)}]2 (3). The reaction of germanium(I) dimer 2 with 1
equiv of azobenzene afforded compound 3 (Scheme 1).
Compound 3 was formed from the cleavage of the Ge(I)−
Ge(I) bond followed by the insertion of the NN moiety of
the azobenzene between the germanium(I) centers. The formal
oxidation state of both germanium atoms in 3 has changed
from +1 to +2. Similar reactions of a terphenyl-stabilized
digermyne and an amidinate-stabilized germanium(I) dimer
with azobenzene have been reported by the groups of Power12
and Roesky,9a respectively.
When compound 2 was treated with 2 equiv of Fe2(CO)9,
the corresponding Lewis acid−base adduct 5, with two
Fe(CO)4 moieties coordinating to the two germanium(I)
atoms, was isolated as a dark red crystalline solid (Scheme 1).
The elemental analysis for 5 is consistent with the proposed
1
structure of 5. Both the H and 13C NMR spectra and IR
Synthesis of [{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)(Fe-
(CO)4)GeGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}] (4) and
[{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)Ge(Fe(CO)4)]2 (5). Reac-
tion of 2 with 1 equiv of diiron nonacarbonyl afforded
compound 4, which was isolated as a dark red crystalline solid.
Alternatively, compound 4 can also be prepared by the reaction
of chlorogermylene 1 with Collman’s reagent, Na2FeCO4
(Scheme 1).
Upon the addition of compound 1 to Na2Fe(CO)4,
compound 1 was first reduced by Na2Fe(CO)4 to give dimer
2, while the [Fe(CO)4]2− ion was oxidized to Fe(CO)4. A 1:1
mixture of the germanium(I) dimer 2 and a Fe(CO)4 moiety
was formed. The Fe(CO)4 moiety is coordinated to one of the
germanium(I) centers in 2, leading to the formation of the
unsymmetric germanium(I) dimer 4 with different coordina-
spectrum of 5 are consistent with the structure of compound 5.
However, attempts to isolate good-quality crystals of 5 for X-
ray structural determination have been unsuccessful. It is
noteworthy that compound 5 can also be obtained from the
addition of the unsymmetric germanium(I) dimer 4 to 1 equiv
of Fe2(CO)9. This indicates that the stereoactive lone pair on
the three-coordinated germanium(I) center in 4 can function as
a base to react with another Fe(CO)4 moiety. The existence of
compound 5 in the product mixture was confirmed by NMR
and IR studies.
Spectroscopic Properties. Compounds 3−5 were isolated
as orange or dark red crystalline solids which decompose
readily upon contact with air or moisture. They are soluble in
THF, diethyl ether, and toluene but sparingly soluble in hexane.
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Figure 2. Molecular structure of [PhNGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}]2 (3). Hydrogen atoms are omitted for clarity, and 30%
probability thermal ellipsoids are shown. Selected bond distances (Å) and angles (deg): Ge(1)−N(1) = 2.079(3), Ge(1)−N(2) = 1.945(3), Ge(1)−
N(3) = 1.953(3), Ge(2)−N(4) = 1.961(3), Ge(2)−N(5) = 2.081(3), Ge(2)−N(6) = 1.967(3), N(3)−N(4) = 1.454(4), N(1)−C(5) = 1.351(5),
N(2)−C(10) = 1.403(5), N(3)−C(20) = 1.388(4); N(2)−Ge(1)−N(3) = 99.8(1), N(2)−Ge(1)−N(1) = 87.1(1), N(3)−Ge(1)−N(1) =
102.4(1), N(4)−Ge(2)−N(6) = 106.2(1), N(4)−Ge(2)−N(5) = 103.1(1), N(6)−Ge(2)−N(5) = 87.5(1), C(20)−N(3)−N(4) = 116.3(3),
C(20)−N(3)−Ge(1) = 134.3(2), N(4)−N(3)−Ge(1) = 98.0(2), N(3)−N(4)−Ge(2) = 107.7(2).
1
The H NMR spectrum of 3 displays two singlets at δ −0.32
and −0.21 ppm due to the protons in the two different SiMe3
groups. Signals due to the pyridyl and phenyl protons are
observed at δ 6.55−7.67 ppm. The 13C NMR spectrum of 3
displays two sharp singlets at δ 1.63 and 2.24 ppm for the two
germanium(I) dimer 2 (2.057(3) and 1.955(4) Å). They are
also similar to those reported for amidinate-stabilized and
terphenyl-stabilized germanium(II) hydrazine derivatives
(1.905 Å (av) for [PhC(NBut)2Ge(Ph)NN(Ph)Ge-
(NBut)2CPh];9a 1.879 Å (av) for [(2,6-Trip2C6H3)Ge(Ph)-
NN(Ph)Ge(2,6-Trip2-C6H3)]).12 The N−N bond distance in
compound 3 is 1.454(4) Å. The bond distance is consistent
with a single N−N bond (1.46 Å for (H3Si)2NN(SiH3)2)14 and
agrees with the bond distances of 1.436(4) Å in [PhC-
(NBut)2Ge(Ph)NN(Ph)Ge(NBut)2CPh]9a and 1.45(3) Å in
[(2,6-Trip2C6H3)Ge(Ph)NN(Ph)Ge(2,6-Trip2C6H3)].12 The
comparison of the N−N bond distance in compound 3 with
those observed in the analogous species [PhC(NBut)2Ge(Ph)-
NN(Ph)Ge(NBut)2CPh] and [(2,6-Trip2C6H3)Ge(Ph)NN-
(Ph)Ge(2,6-Trip2C6H3)] is indicative of the presence of a
single N−N bond in 3. In compound 3, both of the germanium
atoms are three-coordinated. The sum of bonding angles
(293.1° (av)) at the germanium(II) centers is consistent with
the presence of a stereoactive lone pair. Hence, the reaction of
2 with 1 equiv of azobenzene can be regarded as an oxidative
insertion reaction with simultaneous Ge(I)−Ge(I) bond
cleavage.
The molecular structure of 4 is depicted in Figure 3. Selected
bond distances and angles are given in the figure caption. The
Ge(2) atom, which is coordinated with a Fe(CO)4 moiety,
adopts a tetrahedral geometry with the germanium atom Ge(2)
bonding to the Ge(1) atom, the Fe(1) atom, and the two
nitrogen atoms N(3) and N(4). A similar coordination
geometry is also observed for the amidinate-stabilized
germanium(I)−iron complex LGe[Fe(CO)4]Ge[Fe(CO)4]L
(L = PhC(NBut)2).9a The other Ge(1) center is three-
coordinated and adopts a trigonal-pyramidal geometry. The
Ge(1) atom is bonded to a Ge(2) atom and the two nitrogen
atoms N(1) and N(2). The sum of bonding angles at Ge(1) is
292.7(1)°, which is consistent with the presence of a
stereoactive lone pair. The Ge(1)−Ge(2) bond distance of
2.611(1) Å in 4 is within the range of Ge−Ge single-bond
1
different carbons in each of the azaallyl ligands. Both the H
and 13C NMR spectra are consistent with the solid-state
1
structure. The H NMR spectrum of 5 shows two singlet
signals at δ −0.05 and −0.02 ppm due to the two SiMe3 groups
within the symmetric molecule. In addition, the H NMR
1
spectrum of 4 displays four singlet signals at δ −0.20, −0.13,
−0.11, and −0.06 ppm for the protons in the four different
SiMe3 groups due to the unsymmetrical nature of 4. In both
spectra, signals are also observed due to the pyridyl and phenyl
protons (δ 6.80−8.49 ppm for 4, δ 7.38−8.82 ppm for 5).
Both compounds have also been characterized by infrared
spectroscopy. The CO stretching frequencies of 2006 (s), 1923
(s), and 1900 (s) cm−1 in 4 and 2032 (s), 1987 (s), and 1912
(s) cm−1 in 5 are similar to those reported for LGe[Fe(CO)4]-
Ge[Fe(CO)4]L (2029 (m), 1974 (s), and 1920 (s) cm−1; L =
PhC(NBut)2)9a and [HC(CMeNAr)2Ge(OH)Fe(CO)4] (2039
(s), 1956 (s), and 1942 (s) cm−1).13 In these compounds, the
iron atoms adopt a trigonal-bipyramidal geometry while the
iron-coordinated germanium atoms adopt a distorted-tetrahe-
dral geometry.
X-ray Structures. The molecular structure of 3 is depicted
in Figure 2. Selected bond distances and angles are also given in
the figure caption. Both of the germanium(II) centers in
compound 3 adopt a trigonal-pyramidal geometry, with the
germanium atom Ge(1) bonded to the three nitrogen atoms
N(1), N(2), and N(3). The Ge(1)−N(1) dative bond distance
of 2.079(3) Å is slightly longer than the Ge(1)−N(2) and the
Ge(1)−N(3) distances of 1.945(3) and 1.953(3) Å, respec-
tively. Similarly, the Ge(1)−N(5) coordinate bond distance of
2.081(3) Å is slightly longer than the other two Ge−N single-
bond distances of 1.961(3) and 1.967(3) Å. These distances are
comparable to other dative bond distances found in the
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complex LGeFe(η5-C5H5)(CO)2 (L = CH{CMe(NAr)}2, Ar =
2,6-iPr2C6H3).21
CONCLUSIONS
■
In conclusion, we have synthesized the digermahydrazine
derivative [LGeNPh]2 (3) from the reaction of LGeGeL (2)
with azobenzene. The reaction of dimer 2 with 2 equiv of diiron
nonacarbonyl afforded the diiron complex [LGe(Fe(CO)4)]2
(5); whereas the reaction of 2 with 1 equiv of diiron
nonacarbonyl yielded a novel unsymmetric germanium(I)
dimer with two different germanium(I) centers.
EXPERIMENTAL SECTION
■
General Procedures. All manipulations were carried out under an
inert atmosphere of dinitrogen gas by standard Schlenk techniques.
Solvents were dried over and distilled from CaCl2 (hexane and
CH2Cl2) and/or Na (Et2O, toluene, and THF). The pyridyl-1-azaallyl
germanium(II) chloride 1 was prepared according to the literature
procedure.10 Azobenzene and diiron nonacarbonyl were purchased
from Aldrich Chemical Co. and used without further purification. The
Figure 3. Molecular structure of [{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-
2)(Fe(CO)4)GeGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}] (4). Hy-
drogen atoms are omitted for clarity, and 30% probability thermal
ellipsoids are shown. Selected bond distances (Å) and angles (deg):
Ge(1)−Ge(2) = 2.611(1), Ge(2)−Fe(1) = 2.400(1), Ge(1)−N(1) =
2.052(3), Ge(1)−N(2) = 1.912(2), Ge(2)−N(3) = 2.088(2), Ge(2)−
N(4) = 1.940(2), Fe(1)−C(39) = 1.765(4), O(1)−C(39) = 1.146(5);
Fe(1)−Ge(2)−Ge(1) = 131.7(2), N(2)−Ge(1)−N(1) = 87.3(1),
N(2)−Ge(1)−Ge(2) = 110.5(1), N(1)−Ge(1)−Ge(2) = 94.9(1),
N(4)−Ge(2)−N(3) = 89.4(1), N(4)−Ge(2)−Fe(1) = 119.4(1),
N(3)−Ge(2)−Fe(1) = 105.5(1), N(4)−Ge(2)−Ge(1) = 106.6(1),
N(3)−Ge(2)−Ge(1) = 87.8(1), C(41)−Fe(1)−Ge(2) = 86.2(1).
NMR spectra were recorded on Bruker 400 MHz spectrometers and
̈
recorded in THF-d8. The chemical shifts δ are relative to SiMe4 for 1H
and 13C{1H}.
Synthesis of [PhNGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}]2 (3).
A solution of [N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)]2Ge2 (2; 0.80 g,
0.97 mmol) in THF (25 mL) was added slowly to a stirred solution of
azobenzene (0.18 g, 0.99 mmol) in THF (10 mL) at 0 °C. The
resultant dark green mixture was warmed to ambient temperature and
stirred for 24 h. The solution was filtered, and the volatiles were
removed under reduced pressure. The dark red residue was extracted
with toluene. After filtration, concentration of the filtrate afforded red
crystals. Yield: 0.16 g (21%). Mp: 201−204 °C. Anal. Found: C, 58.98;
H, 6.61; N, 8.11. Calcd for C50H64Ge2N6Si4: C, 59.65; H, 6.41; N,
distances reported for other germanium(I) dimers (2.506(1)−
2.709(1) Å),6,7 supporting the Ge−Ge single-bond character in
compound 4. In comparison, it is slightly shorter than that of
2.7093(7) Å reported for Jones’ amido-digermyne with a Ge−
Ge single bond (LGeGeL: L = N(SiMe3)(Ar*); Ar* =
C6H2Me{C(H)Ph2}2-4,2,6)).15 In addition, the Ge−Ge sin-
gle-bond distance is slightly longer than the Ge−Ge donor−
acceptor bond distance of 2.427(1) Å in the phosphine-
stabilized heterocyclic germavinylidene complex.16 It is also
longer than the Ge−Ge double bond in the NHC-stabilized
digermanium(0) complex (2.349(1) Å)17 and much longer
than the Ge−Ge triple bonds found in digermynes (2.206(1)−
2.285(1) Å).3a,18 These further support the presence of single-
bond character of the Ge−Ge interaction in compound 4. It is
also noteworthy that the Ge−Ge bond of 2.611(1) Å in 4 is
similar to that of 2.602(8) Å in 2, showing that the addition of a
Fe(CO)4 moiety to the germanium(I) center has little effect on
the Ge(I)−Ge(I) bond distance. The iron atom adopts a
trigonal-bipyramidal geometry: four of the coordinating sites
are occupied by carbonyl groups and one by the Ge(2) atom.
The Ge(2)−Fe(1) bond distance of 2.400(1) Å is similar to
that of 2.340(1) Å in LGe[Fe(CO)4]Ge[Fe(CO)4]L (L =
PhC(NBut)2).9a It is also comparable to other reported
examples where the Fe(CO)4 moiety is attached to a
germanium atom in the formal oxidation state of +2. The
Ge(2)−Fe(1) bond distance of 2.400(1) Å in compound 4 is
similar to that of 2.33(1) Å in [HC(CMeNAr)2Ge(OH)Fe-
(CO)4 ]13 and that of 2.348(1) Å in [(η3 -(μ-
ButN)2(SiMeNBut)2)GeFe(CO)4],19 but it is slightly longer
in comparison with that of 2.29(2) Å in [HC(CMeNAr)2Ge-
(Cl)Fe(CO)4].20 The Ge−Fe coordinate bond distance of
2.400(1) Å in compound 4 is also comparable to the Ge−Fe
single-bond distance of 2.496(2) Å in the iron−germylene
1
8.35. H NMR (THF-d8): δ −0.32 (s, 9H, SiMe3), −0.21 (s, 9H,
SiMe3), 6.55−6.61 (m, 1H, 5-py), 6.84−6.90 (m, 5H, Ph), 7.12−7.20
(m, 5H, NPh), 7.31−7.35 (m, 1H, 3-py), 7.38−7.42 (m, 1H, 4-py),
7.67 (d, 1H, 6-py, 2JH−H′ = 6.3 Hz). 13C{1H} NMR (THF-d8): δ 1.63,
2.24 (SiMe3), 118.7 (CSiMe3), 120.3−152.6 (Ph and Py), 161.0
(NCPh).
Synthesis of [{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)(Fe(CO)4)-
GeGe{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}] (4). A solution of [N-
(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)]2Ge2 (2; 0.75 g, 0.91 mmol) in
THF (20 mL) was added slowly to a stirred solution of diiron
nonacarbonyl (0.33 g, 0.91 mmol) in THF (10 mL) at 0 °C. The
resultant mixture was warmed to ambient temperature and stirred for
24 h. The solution was filtered, and the volatiles were removed under
reduced pressure. The dark red residue was extracted with 30 mL of
toluene. The solution was then filtered. Addition of 5 mL of THF
followed by concentration of the filtrate afforded dark red crystals.
Yield: 0.42 g (47%). Mp: 182−184 °C. Anal. Found: C, 50.11; H,
6.17; N, 6.28. Calcd for C42H54FeGe2N4O4Si4: C, 50.83; H, 5.48; N,
1
5.65. H NMR (THF-d8): δ −0.20 (s, 9H, SiMe3), −0.13 (s, 9H,
SiMe3), −0.11 (s, 9H, SiMe3), −0.06 (s, 9H, SiMe3), 6.80−7.18 (m,
2H, 5-py), 7.22−7.55 (m, 10H, Ph), 7.60−7.68 (m, 2H, 3-py), 7.71−
7.92 (m, 2H, 4-py), 8.20−8.49 (m, 2H, 6-py). 13C{1H} NMR (THF-
d8): δ 1.55, 1.60, 1.63, 2.04 (SiMe3), 111.0, 112.2 (CSiMe3), 120.3−
152.6 (Ph and Py), 159.0, 161.1 (NCPh), 202.5, 205.7 (CO). IR (KBr,
cm−1): ν(CO) 2006 (s), 1923 (s), 1900 (s).
Synthesis of 4 from 1 and Na2Fe(CO)4. A solution of
[{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}GeCl] (1; 0.47 g, 1.05
mmol) in THF (25 mL) was added slowly to a stirring solution of
Na2Fe(CO)4 (0.11 g, 0.51 mmol) in THF (20 mL) at −90 °C. The
resultant dark red mixture was warmed to ambient temperature and
stirred for 12 h. The solution was filtered, and the volatiles were
removed under reduced pressure. The red residue was extracted with
20 mL of toluene. After filtration, addition of 5 mL of THF and
concentration of the filtrate afforded dark red crystals. Yield: 0.31 g
(61%).
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Synthesis of [{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)(Fe(CO)4)Ge]2
(5). A solution of [N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)]2Ge2 (2;
0.88 g, 1.07 mmol) in THF (20 mL) was added slowly to a stirred
solution of diiron nonacarbonyl (0.78 g, 2.14 mmol) in THF (20 mL)
at 0 °C. The resultant mixture was warmed to ambient temperature
and stirred for 24 h. The volatiles were then removed under reduced
pressure. The dark red residue was extracted with 30 mL of ether. The
solution was filtered, and concentration of the filtrate afforded a dark
red crystalline solid. Yield: 0.06 g (48%). Mp: 195−199 °C. Anal.
Found: C, 48.18; H, 4.88; N, 5.21. Calcd for C46H54Fe2Ge2N4O8Si4: C,
Rev. 2011, 111, 354−396. (k) Lee, V. Y.; Sekiguchi, A. Inorg. Chem.
2011, 50, 12303−12314. (l) Yao, S.; Xiong, Y.; Driess, M.
Organometallics 2011, 30, 1748−1767. (m) Sen, S. S.; Khan, S.;
Nagendran, S.; Roesky, H. W. Acc. Chem. Res. 2012, 45, 578−587.
(n) Hadlington, T. J.; Hermann, M.; Li, J.; Frenking, G.; Jones, C.
Angew. Chem., Int. Ed. 2013, 52, 10199−10203.
(2) Pu, L.; Twamley, B.; Power, P. P. J. Am. Chem. Soc. 2000, 122,
3524−3525.
(3) (a) Stender, M.; Phillips, A. D.; Wright, R. J.; Power, P. P. Angew.
Chem., Int. Ed. 2002, 41, 1785−1787. (b) Power, P. P. Chem. Commun.
2003, 2091−2101. (c) Pu, L. H.; Phillips, A. D.; Richards, A. F.;
Stender, M.; Simons, R. S.; Olmstead, M. M.; Power, P. P. J. Am.
Chem. Soc. 2003, 125, 11626−11636.
(4) Phillips, A. D.; Wright, R. J.; Olmstead, M. M.; Power, P. P. J. Am.
Chem. Soc. 2002, 124, 5930−5931.
(5) Sekiguchi, A.; Kinjo, R.; Ichinohe, M. Science 2004, 305, 1755−
1757.
1
47.62; H, 4.69; N, 4.83. H NMR (THF-d8): δ −0.05 (s, 9H, SiMe3),
−0.02 (s, 9H, SiMe3), 7.38−7.46 (m, 5H, Ph), 7.58−7.61 (m, 1H, 5-
py), 7.70 (d, 1H, 3-py, 2JH−H′ = 6.5 Hz), 8.00 (t, 1H, 4-py, 2JH−H′ = 6.5
Hz), 8.82 (d, 1H, 6-py, 2JH−H′ = 6.5 Hz). 13C{1H} NMR (THF-d8): δ
2.43, 3.44 (SiMe3), 112.1 (CSiMe3), 121.3−157.0 (Ph and Py), 161.9
(NCPh), 201.5, 203.1 (CO). IR (KBr, cm−1): ν(CO) 2032 (s), 1987
(s), 1912 (s).
Synthesis of 5 from 4. A solution of [{N(SiMe3)C(Ph)C-
(SiMe3)(C5H4N-2)(Fe(CO)4)GeGe{N(SiMe3)C(Ph)C(SiMe3)-
(C5H4N-2)}] (4; 0.42 g, 0.42 mmol) in THF (20 mL) was added
slowly to a stirred solution of diiron nonacarbonyl (0.16 g, 0.44 mmol)
in THF (10 mL) at 0 °C. The resultant mixture was warmed to
ambient temperature and stirred for 24 h. The volatiles were removed
under reduced pressure. The dark red residue was extracted with 30
mL of ether. The solution was filtered, and concentration of the filtrate
afforded a dark red crystalline solid. Yield: 0.32 g (66%).
X-ray Crystallography. Single crystals were sealed in Lindemann
glass capillaries under nitrogen. X-ray data of 3 and 4 were collected
on a Rigaku R-AXIS II imaging plate using graphite-monochromated
Mo Kα radiation (λ = 0.71073 Å) from a rotating-anode generator
operating at 50 kV and 90 mA. Crystal data are summarized in Table 1
in the Supporting Information. The structures were solved by direct
phase determination using the computer program SHELXTL-PC22 on
a PC 486 and refined by full-matrix least squares with anisotropic
thermal parameters for the non-hydrogen atoms. Hydrogen atoms
were introduced in their idealized positions and included in structure
factor calculations with assigned isotropic temperature factor
calculations.
(6) (a) Jambor, R.; Kasna, B.; Kirschner, K. N.; Schurmann, M.;
Jurkschat, K. Angew. Chem., Int. Ed. 2008, 47, 1650−1653.
(b) Nagendran, S.; Sen, S. S.; Roesky, H. W.; Koley, D.;
̈
Grubmuller, H.; Pal, A.; Herbst-Irmer, R. Organometallics 2008, 27,
̈
5459−5463. (c) Sen, S. S.; Jana, A.; Roesky, H. W.; Schulzke, C.
Angew. Chem., Int. Ed. 2009, 48, 8536−8538. (d) Wang, W.; Inoue, S.;
Yao, S.; Driess, M. Chem. Commun. 2009, 2661−2663. (e) Leung, W.-
P.; Chiu, W.-K.; Chong, K.-H.; Mak, T. C. W. Chem. Commun. 2009,
6822−6824. (f) Jones, C.; Bonyhady, S. J.; Holzmann, N.; Frenking,
G.; Stasch, A. Inorg. Chem. 2011, 50, 12315−12325. (g) Chia, S.-P.;
Yeong, H.-X.; So, C.-W. Inorg. Chem. 2012, 51, 1002−1010. (h) Khan,
S.; Michel, R.; Dieterich, J. M.; Mata, R. A.; Roesky, H. W.; Demers, J.-
P.; Lange, A.; Stalke, D. J. Am. Chem. Soc. 2011, 133, 17889−17994.
(i) Chia, S.-P.; Ganguly, R.; Li, Y.; So, C.-W. Organometallics 2012, 31,
6415−6419.
(7) Green, S. P.; Jones, C.; Junk, P. C.; Lippert, K.-A.; Stasch, A.
Chem. Commun. 2006, 3978−3980.
(8) (a) Sen, S. S.; Khan, S.; Nagendran, S.; Roesky, H. W. Acc. Chem.
Res. 2012, 45, 578−587. (b) Sen, S. S.; Khan, S.; Samuel, P. P.; Roesky,
H. W. Chem. Sci. 2012, 3, 659−682. (c) Blom, B.; Stoelzel, M.; Driess,
M. Chem. Eur. J. 2013, 19, 40−62.
(9) (a) Sen, S. S.; Kratzert, D.; Stern, D.; Roesky, H. W.; Stalke, D.
Inorg. Chem. 2010, 49, 5786−5788. (b) Zhang, S.-H.; So, C.-W.
Organometallics 2011, 30, 2059−2062.
ASSOCIATED CONTENT
* Supporting Information
CIF files and a table giving X-ray crystallographic data for the
structure determinations of 3 and 4. This material is available
free of charge via the Internet at http://pubs.acs.org.
■
S
(10) Leung, W.-P.; So, C.-W.; Wu, Y.-S.; Li, H.-W.; Mak, T. C. W.
Eur. J. Inorg. Chem. 2005, 3, 513−521.
(11) (a) Leung, W.-P.; Chong, K.-H.; Wu, Y.-S.; So, C.-W.; Chan, H.-
S.; Mak, T. C. W. Eur. J. Inorg. Chem. 2006, 808−812. (b) Leung, W.-
P.; So, C.-W.; Chong, K.-H.; Kan, K.-W.; Chan, H.-S.; Mak, T. C. W.
Organometallics 2006, 25, 2851−2858. (c) Leung, W.-P.; Chiu, W.-K.;
Mak, T. C. W. Organometallics 2012, 31, 6966−6971.
(12) Cui, C.; Olmstead, M. M.; Fettinger, J. C.; Spikes, G. H.; Power,
P. P. J. Am. Chem. Soc. 2005, 127, 17530−17541.
AUTHOR INFORMATION
Corresponding Author
*E-mail for W.-P.L.: kevinleung@cuhk.edu.hk.
Notes
■
The authors declare no competing financial interest.
(13) Pineda, L. W.; Jancik, V.; Colunga-Valladares, J. F.; Roesky, H.
W.; Hofmeister, A.; Magull, J. Organometallics 2006, 25, 2381−2383.
(14) Glidewell, C.; Rankin, D. W. H.; Robiette, A. G.; Sheldrick, G.
M. J. Chem. Soc. A 1970, 318−320.
ACKNOWLEDGMENTS
■
This work was supported by the Research Grants Council of
The Hong Kong Special Administrative Region, People’s
Republic of China (Project No. CUHK 402210).
(15) Li, J.; Schenk, C.; Goedecke, C.; Frenking, G.; Jones, C. J. Am.
Chem. Soc. 2011, 133, 18622−18625.
(16) Leung, W.-P.; Chiu, W.-K.; Mak, T. C. W. Inorg. Chem. 2013,
52, 9479−9486.
REFERENCES
(17) Sidiropoulos, A.; Jones, C.; Stasch, A.; Klein, S.; Frenking, G.
Angew. Chem., Int. Ed. 2009, 48, 9701−9704.
■
(1) Selected reviews: (a) Bourget-Merle, L.; Lappert, M. F.; Severn, J.
R. Chem. Rev. 2002, 102, 3031−3066. (b) Kuhl, O. Coord. Chem. Rev.
(18) Sugijama, Y.; Sasamori, T.; Hosoi, Y.; Furukawa, Y.; Takagi, N.;
Nagase, S.; Tokitoh, N. J. Am. Chem. Soc. 2006, 128, 1023−1031.
(19) Saur, I.; Rima, G.; Miqueu, K.; Gornitzka, H.; Barrau, J. J.
Organomet. Chem. 2003, 672, 77−85.
̈
2004, 248, 411−427. (c) Power, P. P. Organometallics 2007, 26,
4362−4372. (d) Leung, W.-P.; Kan, K.-W.; Chong, K.-H. Coord. Chem.
Rev. 2007, 251, 2253−2265. (e) Nagendran, S.; Roesky, H. W.
Organometallics 2008, 27, 457−492. (f) Mizuhata, Y.; Sasamori, T.;
Tokitoh, N. Chem. Rev. 2009, 109, 3479−3511. (g) Power, P. P.
Nature 2010, 463, 171−177. (h) Fischer, R. C.; Power, P. P. Chem.
Rev. 2010, 110, 3877−3923. (i) Mandal, S. K.; Roesky, H. W. Chem.
Commun. 2010, 6016−6041. (j) Asay, M.; Jones, C.; Driess, M. Chem.
(20) Veith, M.; Becker, S.; Huch, V. Angew. Chem., Int. Ed. 1990, 29,
216−218.
(21) Inoue, S.; Driess, M. Organometallics 2009, 28, 5032−5035.
(22) Sheldrick, G. M. In Crystallographic Computing 3: Data
Collection, Structure Determination, Proteins, and Databases; Sheldrick,
229
dx.doi.org/10.1021/om4009839 | Organometallics 2014, 33, 225−230

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Article
G. M., Kruger, C., Goddard, R., Eds.; Oxford University Press: New
York, 1985; pp 175−189.
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