Synthesis and Structure of Tin and Germanium Complexes as Precursors Containing Alkoxyaminoalkoxide Ligands for Thin Film Transistors

Article abstract of DOI:10.1002/ejic.202000167

This paper describes the preparation of four novel Sn and Ge complexes containing alkoxyaminoalkoxide type ligands {L1H = 1-[methoxy(methyl)amino]-2-methylpropan-2-ol; L2H = 1-[methoxy(methyl)amino]-2-methylbutan-2-ol} for potential use as precursors for thin film transistors. All compounds were prepared at room temperature by stirring a solution containing Sn(btsa)₂ [btsa = bis(trimethylsilyl)amide] or Ge(btsa)₂ with two equivalents of L1H or L2H to form Sn(L1)₂ (1), Sn(L2)₂ (2), Ge(L1)₂ (3) and Ge(L2)₂ (4). All of the complexes were characterized by NMR and FTIR spectroscopy as well as elemental and thermogravimetric analyses. When the more symmetric and compact ligand L1H was applied, solid products 1 and 3 were generated and their structures were studied using X-ray diffraction. Applying the strategy of ligand design at the molecular level, the symmetric ligand was changed to an asymmetric one, replacing one of the two neighboring methyl groups of the amino alcohol group with an ethyl group, and forming liquid complexes 2 and 4 for both metals.

Full text of DOI:10.1002/ejic.202000167

European Journal of Inorganic Chemistry
Accepted Article
Title: Synthesis and Structure of Tin and Germanium Complexes as
Precursors Containing Alkoxyaminoalkoxide Ligands for Thin
Film Transistors
Authors: Ga Yeon Lee, Ji Hun Lee, Seong Ho Han, Bo Keun Park,
Chang Gyoun Kim, Dong Ju Jeon, and Taek-Mo Chung
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.202000167
Link to VoR: https://doi.org/10.1002/ejic.202000167
01/2020

10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
Synthesis and Structure of Tin and Germanium Complexes as
Precursors Containing Alkoxyaminoalkoxide Ligands for Thin
Film Transistors
Ga Yeon Lee,[a],[b] Ji Hun Lee,[a] Seong Ho Han,[a],[b] Bo Keun Park,[a] Seung Uk Son,[b] Chang Gyoun
Kim,[a] Dong Ju Jeon,*[a] and Taek-Mo Chung*[a]
[a]
[b]
G. Y. Lee, Dr. J. H. Lee, S. H. Han, Dr. B. K. Park, Dr. C. G. Kim, Dr. D. J. Jeon, Dr. T.-M. Chung
Thin Film Materials Research Center
Korea Research Institute of Chemical Technology (KRICT)
141 Gajeong-ro, Yuseong-gu, Deajeon 34114, Republic of Korea
Email:djjeon@krict.re.kr tmchung@krict.re.kr
G. Y. Lee, S. H. Han, Prof. S. U. Son
Department of Chemistry
Sungkyunkwan University (SKKU)
2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea
Supporting information for this article is given via a link at the end of the document.
Abstract: This paper describes the preparation of four novel Sn and
undergo crystalline-amorphous (order-disorder) phase transitions.
Such phase change leads a large electrical contrast which allows
it to be used as electrical memory.[11–13]
Ge complexes containing alkoxyaminoalkoxide type ligands (L1H = 1-
(methoxy(methyl)amino)-2-methylpropan-2-ol;
L2H
=
1-
(methoxy(methyl)amino)-2-methylbutan-2-ol) for potential use as
precursors for thin film transistors. All compounds were prepared at
room temperature by stirring a solution containing Sn(btsa)2 (btsa =
bis(trimethylsilyl)amide) or Ge(btsa)2 with two equivalents of L1H or
L2H to form Sn(L1)2 (1), Sn(L2)2 (2), Ge(L1)2 (3) and Ge(L2)2 (4). All
of the complexes were characterized by NMR and FTIR
spectroscopies as well as elemental and thermogravimetric analyses.
When the more symmetric and compact ligand L1H was applied, solid
products 1 and 3 were generated and their structures were studied
using X-ray diffraction. Applying the strategy of ligand design at the
molecular level, the symmetric ligand was changed to an asymmetric
one, replacing one of the two neighboring methyl groups of the
aminoalcohol group with an ethyl group, and forming liquid complexes
2 and 4 for both metals.
To fabricate devices that include the materials mentioned,
various techniques have been investigated. For instance, uniform
and transparent semiconducting tin oxide thin films can be
produced by chemical vapor deposition (CVD) using tin
tetraiodide (SnI4), tin tetrachloride (SnCl4), or dimethyltin
dichloride ((CH3)2SnCl2). Conformity of phase changing material
is required for the confined structure of devices which can be
achieved via CVD or atomic layer deposition (ALD). Additionally,
demand for ALD is increasing in the semiconductor industry due
to its advantages of high surface conformity of the deposited
material along with ease of thickness control due to the self-
limiting tendency of the ALD technique.[14–18]
The self-limiting nature of the ALD method depends on the
precursor and reactant gases. By alternating the pulse of the
precursor and reactant gases, successful surface reactions of the
precursor on the substrate occur leading to accurate thickness
control over the desired areas. To achieve an adequate ALD
deposition, the design of the volatile and thermally stable metal
precursor is crucial. As an example, the appropriate knowledge of
the precursor chemistry helps to overcome the barrier of thermal
requirement and reactivity.[19] Moreover, there are only few
studies that report the formation of a GeO2 film by ALD due to the
limited number of available Ge precursors such as germanium
Introduction
The development of oxide semiconductors is one of the most
challenging and extensively studied topics in the thin film
transistor (TFT) industry.[1,2] Since many newly designed devices
for TFTs, optoelectronics, and displays require channel material
with higher mobility and on-off ratio to satisfy the demand, group
14 elements of the periodic table such as tin and germanium are
regarded as the most promising materials for various electronic
applications due to their distinctive characteristics.[3,4] Tin oxide is
well known for its superior transparency, wide band gap of 3.6 eV
at 300 K, and n-type property, and these attributes suit many
possible applications such as transparent electrodes, oxidation
catalysts, and solid state gas sensor devices.[5–10]
ethoxide,
bis(dimethylamido)germanium(N,N'-diisopropyl-
ethylenediamide), and bis(dimethylamido)(N,N'-di-tert-butyl-
ethylenediamide) germanium.[20,21] Although, above materials
were applied for ALD deposition of GeO2 films, the control of
thickness and roughness needs to be examined in more detail.
In this study, we tried to synthesize new types of Sn and Ge
precursors that were modified versions of bis(1-dimethylamino-2-
methyl-2-propoxy)tin [Sn(dmamp)2] reported by our group, which
demonstrated the growth of pure and robust SnO2 films when O3
was introduced as an oxidizing precursor.[22] Herein, two modified
aminoalkoxide-type ligands, L1H, 1-(methoxy(methyl)amino)-2-
Along with tin complexes, increased attention is being shown to
films composed of germanium in phase-change materials. For
instance, Ge2Sb2Te5 (GST) has been regarded as the next
generation semiconductor memory device due to its ability to
1
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
Scheme 1. Synthetic scheme of aminoalkoxide type ligands
methylpropan-2-ol
(mampH)
and
L2H,
1-
Sn(btsa)2 and Ge(btsa)2 were treated with two equivalents of L1H,
1-(methoxy(methyl)amino)-2-methylpropan-2-ol (mampH), under
inert conditions, the corresponding Sn(L1)2 and Ge(L1)2
compounds were formed in acceptable yields. Similarly, when
Sn(btsa)2 and Ge(btsa)2 were treated with L2H, 1-
(methoxy(methyl)amino)-2-methylbutan-2-ol (mambH), Sn(L2)2
and Ge(L2)2 were synthesized in acceptable to excellent yields. It
is worth noting that solid products were formed for compound 1
and 3, and liquid products were produced for compound 2 and 4
when the ethyl group was introduced to form an asymmetric
ligand. The physical properties of complexes 1-4 are listed in
Table 1. All compounds were analyzed by NMR, IR spectroscopy,
elemental analysis and TGA. Furthermore, single crystal X-ray
diffraction analysis was performed on compounds 1 and 3 after
recrystallization from a saturated mixture of hexane and diethyl
ether.
The difference in physical state of the prepared products under
ambient conditions was due to the ligands introduced in this study.
Both ligands mampH and mambH (Scheme 2) synthesized in this
study have a similar structure with a methoxy(methyl)amino group
at one end along with either propanol or butanol at the other end.
Eventually, the asymmetric design of the ligand with the bulkier
end influenced the molecular packing of the prepared compounds
resulting in liquid products, as explained in other work.[23]
(methoxy(methyl)amino)-2-methylbutan-2-ol (mambH), were
used to synthesize a new set of potential Sn and Ge precursors
by introducing the methoxy group to the amino end group and
further replacing one methyl with an ethyl group. The concept of
the asymmetric ligand configuration was adapted from our
previous study where Ni(II) dialkylaminoalkoxide complexes were
investigated to tune the physical state of the prepared complexes
resulting in a less compact molecular packing.[23] Surprisingly,
liquid state Ge- and Sn-precursor were synthesized when
asymmetric alkoxy carbons were introduced.
In this work, new methoxymethylaminoalcohol-type ligands
such as L1H and L2H were studied and further two solid-state and
two liquid-state Sn and Ge complexes synthesized using the
prepared ligands. Tin complexes Sn(mamp)2 (1) and Sn(mamb)2
(2) along with Ge(mamp)2 (3) and Ge(mamb)2 (4) were prepared,
purified, and fully characterized using FTIR and NMR
spectroscopy, elemental analysis, and volatility tests. Single
crystal X-ray structural analysis of complexes 1 and 3 showed
distorted trigonal bipyramidal geometries with a lone pair of
electrons on each metal in the equatorial position.
Complex
State at 25 °C
Melting Point (°C)
1
2
3
4
Solid
Liquid
Solid
64.2
-
73.5
-
Scheme 2. Ligands in this study
Liquid
Table 1. The physical properties of complexes 1-4.
Results and Discussion
Structure of compounds 1 and 3
Synthesis of Sn and Ge complexes
Crystals of complex 1 and 3 were obtained from a saturated
mixed hexane and ether solution at 0 °C, and the X-ray diffraction
analysis was performed at 100 K. The crystallographic data for
complexes 1 and 3 are provided in the Supporting Information,
and the selected bond lengths and angles are shown in Table 2.
The ORTEP views of the tin and germanium compounds are
shown in Fig. 1 and 2.
As shown in Scheme 1, two modified aminoalcohol type ligands
such as 1-(methoxy(methyl)amino)-2-methylpropan-2-ol (mampH,
L1H) and 1-(methoxy(methyl)amino)-2-methylbutan-2-ol (mambH,
L2H) were synthesized by the reaction of N,O-
dimethylhydoxylamine with dialkyloxiranes which were prepared
using the Corey-Chaykovsky reaction in moderate yields.[24]
The synthesis of Sn and Ge compounds using two modified
aminoalcohol ligands is summarized in Scheme 3. When
The X-ray diffraction study showed that the molecular
structures of 1 and 3 are very similar and are monomers at solid
2
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
Table 2. Selected bond lengths (Å ) and bond angles (º) for complexes 1 and
3.
and a constant flow of nitrogen gas. Thermogravimetric analysis
data of compounds 1, 2, 3 and 4 are shown in Fig. 3.
Tin complex 1 displayed a 52% mass loss in the temperature
range from 50 to 240 °C. Further weight loss of approximately
14% was observed between 240−500 °C. The total weight loss
of 1 was approximately 66% and the residue was 34%, which was
thought to be tin monoxide SnO (ideal residue 35%) created by
Complex 1
Sn1–O1
2.0461(15)
2.5919(17)
96.17(9)
Sn1–O1A
2.0460(15)
2.5919(17)
138.79(8)
75.38(6)
Sn1–N1
Sn1–N1A
O1-Sn1-O1A
O1-Sn1-N1
Complex 3
Ge1-O1
N1-Sn1-N1A
O1A-Sn1-N1A
the thermal decomposition of compound
thermogravimetric analysis.
1
during
75.38(6)
Complex 2 showed stepwise decomposition characteristics in
its TG curve, which indicated the unstable nature of the
complexes at moderately high temperatures. The TGA plot of 2
exhibits a mass loss in four steps, the first one of 32% was
displayed at 80 °C, the second step showed a weight loss of
approximately 6% between 80−130 °C, the third weight loss of
7% was observed between 130−200 °C, and the final weight loss
of 5% was determined between 200−300 °C. The total weight
loss of 2 was approximately 60% (residue: 40%). The calculated
value of 37% for the residue (SnO2) was similar to that observed
for 2, which means that the weight loss was caused by thermal
decomposition of the complex instead of evaporation.
Germanium complexes 3 and 4 were more stable than tin
compounds 1 and 2 although they consisted of the same organic
ligands. The germanium complexes displayed a single step on the
TGA curves in the temperature region of 30−250 °C with a mass
loss of 89% (residue: 11%) for 3 and 90% (residue: 10%) for 4,
respectively, which represents an excellent thermal behavior.
1.8444(8)
2.4994(9)
99.36(6)
78.95(3)
Ge1-O1A
1.8445(8)
2.4994(9)
145.68(4)
78.95(3)
Ge1-N1
Ge1-N1A
O1-Ge1-O1A
O1-Ge1-N1
N1-Ge1-N1A
O1A-Ge1-N1A
Symmetry transformations used to generate equivalent atoms: A= −x + 1, y, −z + 1/2.
state. These are structurally characterized monomeric tin(II) and
germanium(II) compounds stabilized by two intramolecular MII←N
coordination bonds.
The MII←N bond lengths are 2.5919 Å for compound 1 and
2.4994 Å for compound 3. The SnII-N bond lengths of complex 1
were provided in a previous study and the reported lengths of SnII-
N bonds were in the range of 2.516(3)–2.660(3) Å.[25] It was
observed that the GeII-N bond lengths for compound 3 were
similar
to
those
of
Ge(dmae)2
(dmae=
2-
(dimethylamino)ethoxide)[26] and are considerably larger than
those of all previously determined GeII-N coordination bonds.[27]
The MII-O bond lengths (2.0460, 2.0461 Å for complex 1 and
1.8444, 1.8445 Å for complex 3, (Table 2)) show the typical M-O
distances for M(OR)2 compounds (range of values for Sn-O bond
lengths is 1.956(7)–2.202(6) Å; the range of Ge-O bond lengths
is 1.765(6)–1.878(4) Å).[28,29] The O-M-O bond angles are
96.17(9)° and 99.36(6)° for compounds 1 and 3, respectively, as
presented in Table 2. The N-M-N bond angles are 138.79(8)° and
145.68(4)° for compounds 1 and 3, respectively, showing that the
angles are also approximately equal to those of M(dmae)2 (M=Sn,
Ge) with the same configuration.[26]
Fig. 1. Crystal structure of ORTEP drawing of complex 1
The X-ray structural study of 1 and 3 shows that the central
M(II) atom in 1 and 3 has a distorted trigonal bipyramidal
configuration with a lone pair of electrons, moreover, the oxygen
atoms are in the equatorial positions and the nitrogen atoms in
the axial positions.
The intention at the beginning of the tin and germanium
precursor development was to design a new ligand which would
consist of a six-membered ring when complexed with the metal
ion. The ligands mampH(L1H) and mambH(L2H) should act as
bidentate ligands with a six-membered ring in which two metal-
oxygen bonds would be formed. However, the methoxy group of
the amino derivatives did not act as a dative oxygen-donor,
resulting in a more stable five-membered ring composed of M-N
and M-O bonds instead of a six-membered ring.
Fig. 2. Crystal structure of ORTEP drawing of complex 3.
Thermal behavior
Conclusion
The thermogravimetric analysis (TGA) was performed on the
newly synthesized complexes, which were investigated up to
500 °C at a heating rate of 10 °C/min under atmospheric pressure
The suitability of four novel Sn and Ge complexes containing
alkoxyaminoalkoxide ligands for potential use as precursors for
thin film transistors was indicated. These complexes were
3
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
synthesized by substitution reactions between Sn(btsa)2 or
Ge(btsa)2 and the corresponding alkoxyaminoalcohols. Applying
the more symmetric and compact ligand L1H, 1 and 3 were
obtained as solid products and their structures were analyzed by
X-ray diffraction. Contrary to this, when the symmetric ligand was
changed to an asymmetric one by replacing one of the methyl
groups with an ethyl group, liquid complexes 2 and 4 were formed
for both metals. Liquid precursors were successfully obtained
from solid ones by introducing asymmetry into the alkoxy carbon
applying the ligand design strategy at the molecular level.
The crystal structures of 1 and 3 indicated a monomer structure
with tetra-coordinated central metal atoms displaying distorted
trigonal bipyramidal geometries with a lone pair of electrons.
Complexes 3 and 4 exhibited considerable thermal stabilities, as
shown by thermal characterization. Their attractive volatilities and
thermal stabilities, confirmed by clean single-step TGA curves
and low nonvolatile residual masses, make them promising
candidates for thin-film deposition techniques.
Synthesis of L1H, 1-(methoxy(methyl)amino)-2-methylpropan-2-ol
(mampH): Na2CO3 (5.43 g, 0.051 mol) was added to a solution of N,O-
dimethyl hydroxylamine hydrochloride (5.00 g, 0.051 mol) in MeOH (100
mL) and H2O (10 mL) at room temperature. The solution was stirred for 1
h. Isobutylene oxide (6.93 mL, 0.077 mol) in MeOH (30 mL) was then
added to the solution. The reaction mixture was refluxed for 12 h and then
CH2Cl2 (200 mL) and water (200 mL) were added to the solution. The
organic layers were separated, and the aqueous layer was extracted
further with CH2Cl2 (2 × 200 mL). The combined organic layers were dried
over anhydrous MgSO4, filtered, and concentrated under vacuum. The
crude product was finally purified by column chromatography using silica
gel with the eluent of MC/MeOH (30:1) to afford pure 1-
(methoxy(methyl)amino)-2-methylpropan-2-ol as a colorless oil (3.78 g,
yield: 57%). 1H NMR (CDCl3, 400 MHz): δ 1.24 (s, 6H, C(CH3)2), 2.28 (s,
3H, NCH3), 2.42 (s, 2H, CH2), 3.15 (s, 1H, OH), 3.20 (s, 3H, OCH3). 13C
NMR (CDCl3, 100 MHz): δ 27.9, 45.6, 58.5, 69.6, 70.5. IR (KBr, cm−1): 910,
1047, 1384, 1459, 2880, 2972, 3462. Anal. Calc. for C6H15NO2: C, 54.1; H,
11.4; N, 10.5%. Found: C, 53.2; H, 11.3; N, 10.0%.
Thin film deposition test of 3 and 4 using the ALD technology is
currently underway and will be reported shortly.
Synthesis
of
L2H,
1-(methoxy(methyl)amino)-2-methylbutan-2-ol
(mambH): Na2CO3 was added (8.00 g, 0.075 mol) to a solution of N,O-
dimethyl hydroxylamine hydrochloride (7.15 g, 0.075 mol) in MeOH (100
mL) and H2O (10 mL), at room temperature. The solution was stirred for 1
h, and then 2-ethyl-2-methyloxirane (9.47 g, 0.110 mol) in MeOH (30 mL)
was added. The reaction mixture was refluxed for 12 h and then CH2Cl2
(200 mL) and water (200 mL) were added to the solution. The organic
layers were separated, and the aqueous layer was extracted further with
CH2Cl2 (2 × 200 mL). The combined organic layers were dried over
anhydrous MgSO4, filtered, and concentrated under vacuum. The crude
product was finally purified by column chromatography using silica gel with
the eluent of MC/MeOH (30:1) to afford pure 1-(methoxy(methyl)amino)-2-
methybutane-2-ol as a colorless oil (6.01 g, yield: 54%). 1H NMR (CDCl3,
400 MHz): δ 0.91 (t, J = 7.52 Hz, 3H, CH2CH3), 1.16 (s, 3H, CCH3), 1.46-
1.63 (m, 2H, CCH2), 2.62 (s, 3H, NCH3), 2.62 (dd, J = 14.2 Hz, 1H, NCHa),
2.65 (dd, J = 14.0 Hz, 1H, NCHb), 3.53 (s, 3H, OCH3). 13C NMR (CDCl3,
100 MHz): δ 8.2, 24.8, 33.5, 45.7, 58.7, 68.8, 71.9. IR (KBr, cm−1): 774,
910, 1047, 1292, 1384, 2880, 2972, 3462. Anal. Calc. for C7H17NO2: C,
57.1; H, 11.6; N, 9.51%. Found: C, 57.2; H, 11.8; N, 9.24%.
Fig. 3. TGA curves for compounds 1 to 4.
Experimental Section
All reactions except the ligand preparations were performed under a dry,
oxygen-free nitrogen or argon atmosphere using standard Schlenk
techniques or a glove box. All solvents were purified with an Innovative
Technology PS-MD-4 solvent purification system. NMR spectra were
recorded on a Bruker 400 MHz spectrometer with benzene-d6 and
chloroform-d as solvents. IR spectra were recorded with a Nicolet Nexus
FT-IR spectrophotometer. Elemental analyses were carried out on a
ThermoScientific OEA Flash 2000 Analyzer. Thermo-gravimetric analyses
were conducted on a SETARAM 92-18 TG-DTA instrument with a constant
flow of nitrogen throughout the experiment. All other chemicals were
purchased from Sigma-Aldrich and Tokyo Chemical Industry Co. Ltd. (TCI)
and used as received.
Scheme 3. Synthetic scheme of tin and germanium complexes
Synthesis of Sn and Ge complexes
Synthesis of Sn(L1)2 (1): 1-(methoxy(methyl)amino)-2-methylpropan-2-ol
(0.30 g, 2.272 mmol) was slowly added to
a solution of tin
Synthesis of 2-disubstituted-1-methoxy(methyl)aminoethanol derivatives
bis(trimethylsilyl)amide [Sn(btsa)2] (0.50 g, 1.136 mmol) in hexane (50 mL)
and then the mixture was stirred at ambient temperature for 12 h. After the
solvent was removed under reduced pressure, and the crude product
4
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
of reflection data were collected as ω scan frames with 0.3°/frame and an
exposure time of 10 s/frame. Cell parameters were determined and refined
by the SMART program. Data reduction was performed using SAINT
software. An empirical absorption correction was applied using the
SADABS program. The structure was solved by direct methods and all
non-hydrogen atoms were subjected to anisotropic refinement by full-
matrix least-squares on F2 using the SHELXTL/PC package. A silver
crystal of complex 1 (a block, 0.38 × 0.10 × 0.06 mm3) and a silver crystal
of complex 3 (a block, 0.30 × 0.20 × 0.20 mm3) were used for crystal- and
intensity-data collection. The structures of complexes 1 and 3 were solved
by direct methods. All non-hydrogen atoms were refined anisotropically.
Complete details of crystal data, intensity collection, and structure
refinements are shown in Table 2. Selected bond lengths and bond angles
are presented in Table 3. Deposition Number 1866371 and 1866372
contain the supplementary crystallographic data for this paper. These data
are provided free of charge by the joint Cambridge Crystallographic Data
Centre and Fachinformationszentrum Karlsruhe Access Structures service
www.ccdc.cam.ac.uk/structures.
purified by recrystallization from the mixture of hexane and ether at 0 °C
to generate white crystals (0.20 g, yield: 46%). 1H NMR (C6D6, 400 MHz):
δ 1.25 (m, 12H, 2 C(CH3)2), 2.74 (s, 10H, 2 NCH3, 2 CH2), 3.41 (s, 6H, 2
OCH3). 13C NMR (C6D6, 100 MHz): δ 32.3, 43.0, 57.0, 71.1, 73.8. IR (KBr,
cm−1): 521, 558, 623, 645, 784, 890, 916, 960, 995, 1017, 1045, 1068,
1126, 1162, 1177, 1292, 1371, 1461, 2808, 2923, 2966. Anal. Calc. for
C12H28N2O4Sn: C, 37.6; H, 7.37; N, 7.31%. Found: C, 37.1; H, 7.37; N,
7.11%.
Synthesis of Sn(L2)2 (2): 1-(methoxy(methyl)amino)-2-methylbutan-2-ol
(0.67 g, 4.544 mmol) was slowly added to a solution of Sn(btsa)2 (1.00 g,
2.272 mmol) in hexane (50 mL), and then the mixture was stirred at
ambient temperature for 12 h. The solvent was removed under reduced
pressure to obtain a pale-yellow liquid (0.78 g, yield: 84%). 1H NMR (C6D6,
400 MHz): δ 1.00-1.15 (bm, 6H, 2 CH2CH3), 1.15–1.21 (bm, 4H, 2 CCH2),
1.36–1.66 (bm, 6H, 2 CCH3), 2.76 (s, 6H, 2 NCH3), 2.61–2.90 (bm, 4H, 2
NCH2), 3.41 (s, 6H, 2 OCH3). 13C NMR (C6D6, 100 MHz): δ 8.3, 27.8, 36.4,
42.4, 56.2, 69.0, 75.0. IR (KBr, cm−1): 503, 565, 777, 882, 996, 1047, 1126,
1178, 1325, 1394, 1457, 2807, 2880, 2936, 2963. Anal. Calc. for
C14H32N2O4Sn: C, 40.9; H, 7.85; N, 6.81%. Found: C, 41.3; H, 8.07; N,
7.02%.
Acknowledgements
This research was supported by a Grant from the development
of smart chemical materials for IoT devices project through the
Korea Research Institute of Chemical Technology (KRICT) of
Republic of Korea (SS2021-20) and Nano Material Technology
Development Program (Green Nano Technology Development
Program) through the National Research Foundation of Korea
(NRF) funded by the Ministry of Education, Science and
Technology (No. 2018M3A7B4065662).
Synthesis of Ge(L1)2 (3): 1-(methoxy(methyl)amino)-2-methylpropan-2-ol
(0.34 g, 2.537 mmol) was slowly added to a solution of germanium
bis(trimethylsilyl)amide [Ge(btsa)2] (0.50 g, 1.268 mmol) in toluene (50 mL)
and then the mixture was stirred at ambient temperature for 12 h. After the
solvent was removed under reduced pressure, the crude product was
purified by recrystallization from the mixture of hexane and ether at 0 °C
to produce white crystals (0.17 g, yield: 40%). 1H NMR (C6D6, 400 MHz):
δ 1.26-1.56 (bm, 12H, 2 C(CH3)2), 2.67 (s, 6H, 2 NCH3), 2.69 (s, 4H, 2
CH2), 3.53 (s, 6H, 2 OCH3). 13C NMR (C6D6, 100 MHz): δ 31.5, 42.7, 56.9,
69.8, 74.9. IR (KBr, cm−1): 512, 561, 621, 799, 958, 912, 931, 985, 1045,
1131, 1179, 1385, 1464, 2810, 2930, 2962. Anal. Calc. for C12H28N2O4Ge:
C, 42.7; H, 8.37; N, 8.31%. Found: C, 41.9; H, 8.07; N, 8.02%.
Keywords: Tin complex • Germanium complex • Precursor •
Atomic layer Deposition • Crystal structures
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1
to generate a pale-yellow liquid (0.31 g, yield: 67%). H NMR (C6D6, 400
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5
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
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6
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10.1002/ejic.202000167
European Journal of Inorganic Chemistry
FULL PAPER
Entry for the Table of Contents
Novel tin and germanium complexes were synthesized as precursors for thin film deposition containing Sn and Ge. Liquid precursors
were obtained from solid ones by introducing asymmetry into the alkoxy carbon, thus switching the substituent on the carbon atom
through ligand design strategy at the molecular level.
Key Topic: Precursor, Tin complex, Germanium complex
7
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