Synthesis and reaction of monomeric germanium(II) and lead(II) dimethylamide and the synthesis of germanium(II) hydrazide by clevage of one N-H bond of hydrazine

Article abstract of DOI:10.1021/ic1003808

The β-diketiminate substituted germanium(II) and lead(II) dimethylamides, LGeNMe₂ (1) and LPbNMe₂ (2), [L = CH{(CMe)₂(2,6-iPr₂C₆H₃N) ₂}] have been synthesized by the reaction of LiNMe₂ with LGeCl and LPbCl respectively. Reaction of compound 1 with an equivalent amount of elemental sulfur leads to the germanium analogue of thioamide, LGe(S)NMe ₂ (3). 2 reacts with 2-benzoyl pyridine (PhCOPy-2) to form the lead(II) alkoxide LPbOC(NMe₂)Ph(2-Py) (4) by nucleophilic addition of "NMe₂" to the carbon oxygen double bond. The reaction of stable N-heterocyclic germylene L¹Ge [L¹ = CH{(C=CH ₂)(CMe)(2,6-iPr₂C₆H₃N)₂}] with hydrazine yields the germanium(II) substituted hydrazide LGeNHNH ₂ (5) by cleavage of one N-H bond of hydrazine. Finally, attempts to isolate lead(II) hydride LPbH from the reaction of 2 with phenylsilane (PhSiH₃) failed, and instead LPbN(2,6-iPr₂C ₆H₃){C(CH₃)CHC(CH₃)=N(2,6-iPr ₂C₆H₃)} (6) was obtained in very low yield. We are able to prove this only by single crystal X-ray structural analysis. Compounds 1, 2, 3, 4, and 5 were characterized by microanalysis, electron impact (EI) mass spectrometry, and multinuclear NMR spectroscopy. Furthermore compounds 1, 2, 5, and 6 were characterized by single crystal X-ray structural analysis, with the result that they are exhibiting monomeric structures in the solid state with trigonal-pyramidal environment at the metal center and a stereochemically active lone pair.

Full text of DOI:10.1021/ic1003808

5554 Inorg. Chem. 2010, 49, 5554–5559
DOI: 10.1021/ic1003808
Synthesis and Reaction of Monomeric Germanium(II) and Lead(II) Dimethylamide
and the Synthesis of Germanium(II) Hydrazide by Clevage of one N-H bond of
Hydrazine
†
,†
‡
†
†
€
Anukul Jana, Herbert W. Roesky,* Carola Schulzke, Prinson P. Samuel, and Alexander Doring
†
€
€
€
Institut fu€r Anorganische Chemie der Universitat Gottingen, Tammannstrasse 4, 37077 Gottingen, Germany,
and ‡School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
Received February 25, 2010
The β-diketiminate substituted germanium(II) and lead(II) dimethylamides, LGeNMe2 (1) and LPbNMe2 (2),[L=CH{(CMe)2-
(2,6-iPr2C6H3N)2}] have been synthesized by the reaction of LiNMe2 with LGeCl and LPbCl respectively. Reaction of
compound 1 with an equivalent amount of elemental sulfur leads to the germanium analogue of thioamide, LGe(S)NMe2 (3). 2
reacts with 2-benzoyl pyridine (PhCOPy-2) to form the lead(II) alkoxide LPbOC(NMe2)Ph(2-Py) (4) by nucleophilic addition of
“NMe2” to the carbon oxygen double bond. The reaction of stable N-heterocyclic germylene L1Ge [L1 = CH{(C=CH2)(CMe)-
(2,6-iPr2C6H3N)2}] with hydrazine yields the germanium(II) substituted hydrazide LGeNHNH2 (5) by cleavage of one N-H
bond of hydrazine. Finally, attempts to isolate lead(II) hydride LPbH from the reaction of 2with phenylsilane (PhSiH3) failed, and
instead LPbN(2,6-iPr2C6H3){C(CH3)CHC(CH3)dN(2,6-iPr2C6H3)} (6) was obtained in very low yield. We are able to prove
this only by single crystal X-ray structural analysis. Compounds 1, 2, 3, 4, and 5 were characterized by microanalysis, electron
impact (EI) mass spectrometry, and multinuclear NMR spectroscopy. Furthermore compounds 1, 2, 5, and 6 were
characterized by single crystal X-ray structural analysis, with the result that they are exhibiting monomeric structures in the
solid state with trigonal-pyramidal environment at the metal center and a stereochemically active lone pair.
Introduction
with small organic substituents using chelating ligands.2-4 In
literature there are some reports on the synthesis of germa-
nium(II) and lead(II) diamides, and also few heteroleptic
germanium(II) and lead(II) amides are known.5 Herein, we
present the synthesis and reaction of the first monomeric
dimethylamido derivative of germanium(II) and lead(II) with
the β-diketiminate ligand.
In recent years the chemistry of carbene and its higher
analogues has received considerable attention because of
their special properties and reactivities.1 Recently we have
reported on the synthesis and reactivity of stable divalent
monomeric silicon, germanium, tin, and lead compounds
Hydrazine and its derivatives are important molecules in
the field of organic and inorganic chemistry since the dis-
covery of a new indole synthesis in 1883 by Emil Fischer.6 In
literature the cleavage of the N-N bond of hydrazine is well
documented by a variety of model systems, while the N-H
bond cleavage of hydrazine is rare.7 N-H bond cleavage of
hydrazine on a metal surface has been reported, and sub-
stitution reactions of the hydrogen atoms of hydrazine are
well-known.8 Herein, we report on N-H bond cleavage of
hydrazine with N-heterocyclic germylene under formation of
germanium(II) substituted hydrazide.
*To whom correspondence should be addressed. E-mail: hroesky@gwdg.
de. Fax: þ49-551-393373.
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Result and Discussion
The reaction of LGeCl with LiNMe2 in diethyl ether
afforded LGeNMe2 (1) in good yield (Scheme 1). It is worth
€
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€
2009, 121, 1126–1129. Jana, A.; Roesky, H. W.; Schulzke, C.; Doring, A. Angew.
Chem., Int. Ed. 2009, 48, 1106–1109. (b) Jana, A.; Roesky, H. W.; Schulzke, C.
Inorg. Chem. 2009, 48, 9543–9548. (c) Jana, A.; Sarish, S. P.; Roesky, H. W.;
Schulzke, C.; Samuel, P. P. Chem. Commun. 2010, 46, 707–709.
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Allg. Chem. 2007, 633, 2205–2209. (b) Jana, A.; Sarish, S. P.; Roesky, H. W.;
€
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r
pubs.acs.org/IC
Published on Web 05/12/2010
2010 American Chemical Society

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5555
mentioning that the reaction of LGeCl with LiN(TMS)2 in
diethyl ether leads exclusively to L1Ge, [L1 = CH{(C=CH2)-
(CMe)(2,6-iPr2C6H3N)2}] instead of LGeN(TMS)2.9
Compound 1 was characterized by 1H NMR spectroscopy,
electron impact (EI) mass spectrometry, and elemental ana-
lysis. The 1H NMR spectrum of 1 shows a singlet at 4.82 ppm
for the γ-CH proton, and two septets (3.43, 3.37 ppm)
corresponding to the CH protons of the iPr moieties. More-
over the signal that arises at δ 2.82 ppm corresponds to
the protons of the NMe2 group. The most abundant ion in
the EI mass spectrum appeared at m/z 491 for [Mþ - NMe2].
1 crystallizes in the triclinic space group P1 with one mono-
mer in the asymmetric unit (Figure 1).
Similarly treatment of LPbCl with LiNMe2 in diethyl ether
afforded the lead(II) amide, LPbNMe2 (2), which was iso-
lated as a pale yellow, very air sensitive, microcrystalline solid
in moderate yield (Scheme 1). 2 was characterized by 1H, 13C,
and 207Pb NMR spectroscopy, EI mass spectrometry, and
Figure 1. Molecular structure of 1. Anisotropic displacement para-
meters are depicted at the 50% probability level, and all restrained refined
˚
hydrogen atoms are omitted for clarity. Selected bond lengths [A] and
1
elemental analysis. The H NMR spectrum of 2 shows a
angles [deg] are Ge1-N1 1.8712(14), Ge1-N2 2.0309(16); N1-Ge1-N2
99.84(7), N1-Ge1-N3 97.01(6).
singlet at 4.73 ppm for the γ-CH proton, and two septets
(δ 3.48, 3.30 ppm) corresponding to the CH protons of the iPr
moieties. Moreover the signal that arises at δ 3.80 ppm corres-
ponds to the protons of the NMe2 group. This resonance is
Scheme 1. Preparation of Compounds 1 and 2
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Table 1. 1H NMR Data of Terminal NMe2 Group in LMNMe2 (M = Ge, Sn,
and Pb)
compounda
1H NMR (δ, ppm)
LGeNMe2 (1)
LSnNMe2
LPbNMe2 (2)
2.82
3.00
3.80
10
a L = CH{(CMe)2(2,6-iPr2C6H3N)2}
shifted downfield compared to that of the analogous germa-
nium and tin compounds (see Table 1).
The 207Pb NMR of 2 exhibits a singlet at 1674 ppm; this
suggests that the NMe2 group is a stronger σ-acceptor, when
compared with that of chloride (207Pb NMR of LPbCl δ
1413 ppm). The most abundant ion in the EI mass spectrum
appeared at m/z 625 for the molecular ion [Mþ - NMe2]. 2
crystallizes in the monoclinic space group C2/m with one
monomer in the asymmetric unit (Figure 2).
We already reported on the synthesis and structure of
LGe(S)X (X = Cl, F, Me, and OH) with Group 14 and 16
elements.11 To the best of our knowledge there are no reports
on amide derivatives containing heavier elements of Group
14 and 16. Herein, we describe the formation of the germa-
nium thionamide LGe(S)NMe2 (3) (Scheme 2). The reaction
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5556 Inorganic Chemistry, Vol. 49, No. 12, 2010
Jana et al.
Scheme 2. Preparation of Compound 3
Scheme 3. Synthesis of Compound 4
Scheme 4. Preparation of Compound 5
Figure 2. Molecular structure of 2. Anisotropic displacement para-
meters are depicted at the 50% probability level, and all restrained refined
˚
hydrogen atoms are omitted for clarity. Selected bond lengths [A] and
angles [deg] are Pb1-N1 2.155(10), Pb1-N2 2.330(7); N1-Pb1-N2
94.3(3), N2-Pb1-N2A 80.7(4).
of LGeNMe2 with equivalent amounts of elemental sulfur at
room temperature in toluene leads after 1 day to the white
compound LGe(S)NMe2 (3) in moderate yield.
Scheme 5. Preparation of Compound 6
Compound 3 is soluble in benzene, tetrahydrofuran (THF),
and n-hexane, and shows no decomposition on exposure to
dry air. Compound 3 was characterized by NMR spectro-
scopy and EI mass spectrometry. The 1H NMR spectrum of 3
exhibits a broad resonance at δ 2.89-2.73 ppm for the amide
(NMe2) protons, which can be compared with the singlet
resonance of 1 (δ 2.82 ppm). The most abundant ion peak in
the EI mass spectrum appeared at m/z 523 [Mþ - NMe2].
Treatment of 2 with 2-benzoyl pyridine at -20 to -10 °C
leads almost quantitatively to the alkoxide 4 (Scheme 3) with
the Pb-O-CNMe2 core. It is worth mentioning that the
corresponding reaction with 1 does not occur even at higher
Here we outline the reaction of L1Ge with hydrazine, under
formation of the germanium(II) substituted hydrazide,
LGeNHNH2 (Scheme 4), which is different when com-
pared with that of the silicon analogue. In the silicon case
there is formation of the silicon(IV) hydrazide L1Si(H)-
NHNH2.14b The synthesis of the first stable germanium(II)
substituted hydrazone, LGeN(H)NCHR (R = CO2Et and
SiMe3) was recently described.15
10
temperature (120 °C), but with LSnNMe2 it proceeds at
room temperature.12 This trend is as expected because the
reactivity of Group 14 amides gradually increases with
increasing radii of the elements. Such an increase of reactivity
was also observed when LGeH2a,d and LSnH3a,b were used.
The 1H NMR spectrum of 4 exhibits a singlet (δ 4.77 ppm)
which can be assigned to the CH proton of the ligand
backbone and another singlet resonance at δ 1.93 ppm for
protons of the NMe2 group which is different from that of
the precursor 2. The 207Pb NMR resonance of 4 arises at
δ 1093 ppm, which is similar to that of the phenolato sub-
stituted β-diketiminate lead compound, LPbO-2,6-tBu2C6H3
(δ 1040 ppm),5d but very much different, when compared with
that of compound 2 (LPbNMe2: δ 1674 ppm).
The addition of hydrazine to a red solution of L1Ge in
toluene leads to a rapid vanishing of the red color (Scheme 5).
From the resulting yellow solution the volatiles were removed in
vacuo, and the residue was extracted with n-hexane. Concentra-
tion of the solution yielded yellow crystals of LGeNHNH2 1(5)
in 85% yield. The composition of 5 was supported by H
NMR spectroscopy, EI mass spectrometry, and elemental
analysis. Furthermore, it was characterized by single crystal
X-ray structural analysis. The 1H NMR spectrum shows
a doublet and triplet resonance (δ 3.16 and 0.87 ppm),
which corresponds to the different protons of the NHNH2
group of 5.
In the last year we have shown that the synthesis of LGeNH2
was achieved by the reaction of N-heterocyclic germylene,
L1Ge, [L1 = CH{(C=CH2)(CMe)(2,6-iPr2C6H3N)2}] with
ammonia gas.13 Consequently, we have demonstrated the
reactivity of the N-heterocyclic silylene, L1Si, with ammonia,
hydrazine, N-methyl hydrazine, and diphenyl hydrazone.14
Single crystals of 5 were obtained from a saturated n-hexane
solution at -32 °C after 4 days. Compound 5 crystallizes in
the triclinic space group P1 with one monomer in the asym-
metric unit. X-ray crystal structure analysis afforded a mon-
omeric structure as illustrated in Figure 3. Surprisingly, 5 is
monomeric in the solid state and what is even more striking,
the NHNH2 group is not involved in any kind of hydrogen
bonding as shown by X-ray structural analysis. Compound 5
(12) Jana, A.; Objartel, I.; Roesky, H. W.; Stalke, D. Dalton. Trans. 2010,
39, 4647-4650.
(13) Jana, A.; Objartel, I.; Roesky, H. W.; Stalke, D. Inorg. Chem. 2009,
48, 798–800.
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131, 4600–4601. (b) Jana, A.; Schulzke, C.; Roesky, H. W.; Samuel, P. P.
Organometallics 2009, 28, 6574–6577.
(15) Jana, A.; Sen, S. S.; Roesky, H. W.; Schulzke, C.; Dutta, S.; Pati,
S. K. Angew. Chem. 2009, 121, 4310–4312. Jana, A.; Sen, S. S.; Roesky, H. W.;
Schulzke, C.; Dutta, S.; Pati, S. K. Angew. Chem., Int. Ed. 2009, 48, 4246–4248.

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5557
is formed via a hydride intermediate accompanied by hydro-
gen elimination.16 From the literature it is known, that metal
hydride reacts with amine to form the metal amide complexes
under elimination of hydrogen.17 Compound 6 crystallizes in
the orthorhombic space group P212121, with one monomer in
the asymmetric unit. The structure of 6 shows that one ligand
is chelating to lead, while the other is monodentate arranged.
This result is due to the steric demand of the two ligands. The
difference in bonding is reflected in the bond lengths within
the ligands. In the monodentate case there are carbon carbon
single and double bonds, which are distinctly different, while
in the chelating ligand the bond lengths are at an average. The
geometry at the lead center is similar to that in compound 2,
which is trigonal pyramidal with a stereochemically active
lone pair.
Figure 3. Molecular structure of 5. Anisotropic displacement para-
meters are depicted at the 50% probability level, and all restrained refined
˚
hydrogen atoms are omitted for clarity. Selected bond lengths [A] and
angles[deg]are Ge1-N11.909(5), N1-N21.053(5), Ge1-N32.0141(19);
N1-Ge1-N3 96.49(13), N2-N1-Ge1 134.6(3).
Summary
In conclusion we have shown the synthesis of a monomeric
germanium(II) and lead(II) dimethylamide derivative and
their reactions. The germanium analogue of thioamide, LGe-
(S)NMe2, was obtained by the reaction of germanium(II)
dimethylamide with equivalent amounts of elemental sulfur.
A lead(II)-alkoxide has been prepared by the reaction of
LPbNMe2 with 2-benzoyl pyridine. Finally we have shown
that one N-H bond of hydrazine is cleaved with L1Ge.
Experimental Section
All manipulations were performed under a dry and oxygen
free atmosphere (N2) using standard Schlenk line techniques
or inside a MBraun MB 150-GI glovebox. All solvents were
dried by a MBraun solvent purifying system prior to use. The
starting materials LGeCl18 and LPbCl4b were prepared using
literature procedures. All other chemicals were purchased
1
commercially and used as received. H and 207Pb NMR
spectra were recorded on a Bruker Avance 500 MHz instru-
ment and referenced to the deuterated solvent in case of the
1H NMR spectra. 207Pb NMR spectrum was referenced to
Pb(Me)4. Elemental analyses were performed by the Analy-
Figure 4. Molecular structure of 6. Anisotropic displacement para-
meters are depicted at the 50% probability level, and all restrained refined
hydrogen atoms and isopropyl groups are omitted for clarity. Selected
˚
bond lengths [A] and angles [deg] are Pb1-N1 2.350(5), Pb1-N2
2.343(5), Pb1-N3 2.268(5), N3-C43 1.352(8), C43-C44 1.369(10),
C44-C45 1.432(9), C45-N4 1.300(9); N1-Pb1-N2 83.04(19),
N2-Pb1-N3 101.74(19).
€
tisches Labor des Instituts fur Anorganische Chemie der
€
€
Universitat Gottingen. EI-MS were measured on a Finnigan
MAT 8230 or a Varian MAT CH5 instrument. Melting
€
points were measured in sealed glass tubes with a Buchi
melting point B 540 instrument.
is stable in the solid state as well as in solution for a longer
period of time without any decomposition under an inert
atmosphere. The geometry about the germanium is trigonal
pyramidal. The germanium is surrounded by two nitrogen
atoms from the backbone of the chelating ligand and the
nitrogen of the NHNH2 group.
Synthesis of LGeNMe2 (1). A solution of LGeCl (0.52 g, 1.0
mmol) in diethyl ether (20 mL) was added drop by drop to a
stirred suspension of LiNMe2 (0.051 g, 1.0 mmol) in diethyl
ether (10 mL) at -78 °C. The reaction mixture was warmed to
room temperature and stirred for another 12 h. The precipitate
was filtered off, and the solvent was partially reduced (ca. 20 mL).
Storage of the remaining solution in a freezer at -32 °C over-
night afforded yellow crystals of 1 suitable for X-ray diffraction
analysis. Yield 0.45 g (84%). Mp 225 °C. 1H NMR (500 MHz,
C6D6): δ 7.12-7.18 (m, 6H, Ar-H), 4.82 (s, 1H, γ-CH), 3.43
(sept, J = 6.86 Hz, 2H, CH(CH3)2), 3.37 (sept, J = 6.86 Hz, 2H,
CH(CH3)2), 2.82 (s, 6H, N(CH3)2), 1.59 (s, 6H, CH3), 1.33 (d,
J = 6.86 Hz, 6H, CH(CH3)2), 1.29 (d, J = 6.86 Hz, 6H,
CH(CH3)2), 1.26 (d, J = 6.86 Hz, 6H, CH(CH3)2), 1.13 (d,
J = 6.86 Hz, 6H, CH(CH3)2) ppm. EI-MS (70 eV): m/z (%): 491
(100) [Mþ - NMe2]. Anal. Calcd for C31H47GeN3 (534.36): C
69.68, H 8.87, N 7.86; Found: C 69.82, H 9.54, N 7.80.
Finally, we tried to prepare the lead(II) hydride, LPbH, by
reaction of LPbCl with AlH3 NMe3, K-selectride, and
3
PhSiH3 respectively, as well as the reaction of LPbN(TMS)2
or LPbNMe2 (2) with PhSiH3. In all cases we obtained the
free ligand (LH) and metallic lead as the major product with
small amounts of LPbN(2,6-iPr2C6H3){C(CH3)CHC(CH3)d
N(2,6-iPr2C6H3)} (6) (Scheme 5). The latter, 6 (Figure 4), has
been analyzed by single crystal X-ray diffraction. The forma-
tion of 6 suggests that LPbH might be formed as an inter-
mediate which immediately decomposed to LH and metallic
lead. In a side reaction the free ligand reacts with LPbH to
form compound 6 under elimination of hydrogen. Power and
co-workers also reported on a lead bonded compound, which
(17) Yu, Y.; Sadique, A. R.; Smith, J. M.; Dugan, T. R.; Cowley, R. E.;
Brennessel, W. W.; Flaschenriem, C. J.; Bill, E.; Cundari, T. R.; Holland,
P. L. J. Am. Chem. Soc. 2008, 130, 6624–6638.
(18) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.; Power,
P. P. Organometallics 2001, 20, 1190–1194.
(16) Pu, L.; Twamley, B.; Power, P. P. J. Am. Chem. Soc. 2000, 122, 3524–
3525.

5558 Inorganic Chemistry, Vol. 49, No. 12, 2010
Jana et al.
Table 2. Crystallographic Data for the Structural Analyses of Compounds 1, 2, 5, and 6
1
2
5
6
empirical formula
formula weight
CCDC no.
C31H47GeN3
534.31
730406
133(2)
triclinic
P1
10.453(2)
12.286(3)
13.016(3)
66.98(3)
80.50(3)
72.40(3)
1464.4(6)
2
1.212
1.069
572
1.70 - 27.02
13048
6309 (Rint = 0.0270)
6309/0/331
0.0279, 0.0640
0.0335, 0.0657
1.055
C31H47N3Pb
668.91
730405
133(2)
monoclinic
C2/m
8.9507(18)
22.604(5)
14.904(3)
90
99.12(3)
90
2977.2(10)
4
1.492
5.689
1344
C29H44GeN4
521.27
745454
133(2)
triclinic
P1
8.6062(17)
11.553(2)
15.055(3)
97.44(3)
98.64(3)
106.20(3)
1397.8(5)
2
1.239
1.119
556
1.87 - 27.04
12150
6002 (Rint = 0.0332)
6002/4/338
0.0419, 0.1006
0.0524, 0.1051
1.027
C64H96N4Pb
1128.64
759550
133(2)
orthorhombic
P212121
15.632(3)
17.187(3)
22.730(5)
90
90
90
6107(2)
4
1.229
2.802
2364
1.49 - 25.94
26179
11787 (Rint = 0.0575)
11787/0/622
0.0475, 0.0768
0.0643, 0.0809
1.030
T [K]
crystal system
space group
˚
a [A]
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
3
˚
V [A ]
Z
Dcalcd [g cm-3
]
μ [mm-1
F(000)
]
θ range [deg]
1.38 - 25.92
12107
reflections collected
independent reflections
data/restraints/parameters
R1, wR2 [I > 2σ(I)]a
R1, wR2 (all data) a
GoF
2956 (Rint = 0.1014)
2956/0/184
0.0667, 0.1752
0.0679, 0.1766
1.143
-3
˚
ΔF(max), ΔF(min) [e A
]
0.331, -0.233
9.439, -4.106
0.920, -0.637
1.665, -1.331
P
P
P
P
a R1 = ||Fo| - |Fc||/ |Fo|. wR2 = [ w(Fo2 - Fc2)2/ w(Fo2)2]0.5
.
Synthesis of LPbNMe2 (2). A solution of LPbCl (0.660 g, 1.0
mmol) in diethyl ether (20 mL) was added drop by drop to a
stirred suspension of LiNMe2 (0.051 g, 1.0 mmol) in diethyl
ether (10 mL) at -78 °C. The reaction mixture was warmed to
room temperature and stirred for another 12 h. The precipitate
was filtered off, and the solvent was partially reduced (ca. 20 mL).
Storage of the remaining solution in a freezer at -32 °C overnight
afforded yellow crystals of 2 suitable for X-ray diffraction
analyses. Yield 0.47 g (70%). Mp 195 °C. 1H NMR (500 MHz,
C6D6): δ 7.10-7.19 (m, 6H, Ar-H), 4.73 (s, 1H, γ-CH), 3.80 (s,
6H, N(CH3)2), 3.48 (sept, J = 6.82 Hz, 2H, CH(CH3)2), 3.30
(sept, J = 6.82 Hz, 2H, CH(CH3)2), 1.71 (s, 6H, CH3), 1.32 (d,
J = 6.82 Hz, 6H, CH(CH3)2), 1.29 (d, J = 6.82 Hz, 6H,
CH(CH3)2), 1.25 (d, J = 6.82 Hz, 6H, CH(CH3)2), 1.16 (d,
J = 6.82 Hz, 6H, CH(CH3)2) ppm. 207Pb NMR (104.63 Hz,
and stored in a freezer at -30 °C. Yellow crystals of 4 are formed
1
after 4 days. Yield: 0.66 g (78%). Mp 164 °C. H NMR (500
MHz, C6D6): δ 7.80 (d, 2H, o-Ph), 7.45 (d, 1H, o-Py), 7.23 (t, 2H,
m-Ph), 7.01-7.18 (m, 7H, Ar-H, p-Ph), 6.80 (t, 1H, p-Py), 6.47 (d,
1H, m-Py), 6.34(m, 1H, m-Py), 4.77 (s, 1H, γ-CH), 3.80-3.40 (br,
4H, CH(CH3)2), 1.93 (s, 6H, N(CH3)2), 1.76 (s, 6H, CH3),
1.33-1.09 (m, 24H, CH(CH3)2) ppm. 207Pb NMR (104.63 Hz,
C6D6): δ 1093 ppm. Anal. Calcd for C43H56N4OPb (852.42): C
60.61, H 6.62, N 6.57; Found C 60.74, H 7.11, N, 6.41.
Synthesis of LGeNHNH2 (5). NH2NH2 (1 mL, 1 M in THF)
was added to a red solution of L1Ge (0.490 g, 1 mmol) in
toluene (20 mL) at 0 °C. The reaction mixture was allowed to
warm to room temperature. After that the reaction mixture
was stirred for additional 30 min. All volatiles were removed in
vacuo, and the residue was extracted with n-hexane (30 mL).
The solution was reduced to half of the volume. Storage of the
solution at -32 °C in a freezer for 2 days yielded 5 as yellow
crystals suitable for single crystal X-ray diffraction analysis.
Yield: 0.44 g (85%). Mp 134 °C. 1H NMR (300 MHz, C6D6): δ
7.10-7.17 (m, 6H, Ar-H), 4.71 (s, 1H, γ-CH), 3.50-3.43 (m,
4H, CH(CH3)2), 3.16 (d, 1H, NH2), 1.59 (s, 6H, CH3), 1.41 (d,
J = 6.67 Hz, 6H, CH(CH3)2), 1.33 (d, J = 6.67 Hz, 6H,
CH(CH3)2), 1.25 (d, J = 6.67 Hz, 6H, CH(CH3)2), 1.13 (d, J =
6.67 Hz, 6H, CH(CH3)2), 0.87 (t, 1H, NH) ppm. EI-MS (70 eV):
m/z (%): 475 (100) [Mþ - (NHNH2, Me)]. Anal. Calcd for
C6D6): δ 1674 ppm. EI-MS (70 eV): m/z (%): 625 (100) [Mþ
NMe2]. Anal. Calcd for C31H47N3Pb (669.35): C 55.66, H 7.08,
N 6.28; Found: C 55.70, H 7.77, N 6.15.
-
Synthesis of LGe(S)NMe2 (3). A solution of 1 (0.530 g, 1.00
mmol) in toluene (30 mL) was slowly added to a suspension of
elemental sulfur (0.032 g, 1.00 mmol) in toluene (15 mL) by
cannula at room temperature. After 0.5 h under constant
stirring at ambient temperature the red solution turned slightly
yellow. All volatiles were removed in vacuo, and the remaining
residue was extracted with toluene (15 mL). The solvent was
removed in vacuo to yield 3 as a slight yellow powder. Yield
0.340 g (60%). Mp 230 °C. 1H NMR (300 MHz, C6D6): δ
7.02-7.16 (m, 6H, Ar-H), 4.70 (s, 1H, γ-CH), 3.47 (sept, J =
6.72 Hz, 2H, CH(CH3)2), 3.15 (sept, J = 6.72 Hz, 2H, CH-
(CH3)2), 2.89-2.73 (br, 6H, N(CH3)2), 1.60 (d, J = 6.72 Hz, 6H,
CH(CH3)2), 1.44 (s, 6H, CH3), 1.29 (d, J = 6.72 Hz, 6H,
CH(CH3)2), 1.18 (d, J = 6.72 Hz, 6H, CH(CH3)2), 1.07 (d,
J = 6.72 Hz, 6H, CH(CH3)2) ppm. EI-MS (70 eV): m/z (%): 523
(100) [Mþ - NMe2].
Synthesis of LPbOC(NMe2)Ph(2-Py) (4). A solution of
2-benzoyl pyridine (0.180 g, 1.00 mmol in 5 mL toluene) was
added by cannula to a solution of 2 (0.670 g, 1.00 mmol in
toluene 20 mL) at -30 °C. The reaction mixture was warmed to
room temperature and stirred for another 2 h. After that all
volatiles were removed in vacuo, and the remaining residue was
extracted with n-hexane (25 mL), concentrated to about 15 mL
C
29H44GeN4 (522.28): C 66.81, H 8.51, N 10.75; Found: C
66.73, H 8.97, N 9.70.
Synthesis of LPbN(2,6-iPr2C6H3){C(CH3)CHC(CH3)dN-
(2,6-iPr2C6H3)} (6). PhSiH3 (0.108 g, 1.00 mmol) was added
by cannula to a solution of 2 (0.670 g, 1.00 mmol in toluene
30 mL) at -78 °C. The reaction mixture was warmed to room
temperature and stirred for another 1 h. After that all volatiles
were removed in vacuo, and the remaining residue was extracted
with n-hexane (40 mL) and concentrated to about 15 mL and
stored in a freezer at -30 °C. A few yellow crystals of 6 formed
after 1 day.
Crystallographic Details for Compounds 1, 2, 5, and 6. Suitable
crystals of 1, 2, 5, and 6 were mounted on a glass fiber and data
was collected on an IPDS II Stoe image-plate diffractometer
˚
(graphite monochromated Mo KR radiation, λ = 0.71073 A) at
133(2) K. The data was integrated with X-Area. The structures

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5559
were solved by Direct Methods (SHELXS-97)19 and refined by
full-matrix least-squares methods against F2 (SHELXL-97).19 All
non-hydrogen atoms were refined with anisotropic displacement
parameters. Crystallographic data are presented in Table 2.
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft.
Supporting Information Available: X-ray data for 1, 2, 5, and 6
(CIF). This material is available free of charge via the Internet at
http://pubs.acs.org.
(19) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–122.