Synthesis and characterization of Nickel(II) aminoalkoxides: Application to molecular precursors for MOCVD of Ni thin films

Article abstract of DOI:10.1002/ejic.201001132

Novel single precursors for Ni, Ni(dmamp)₂ (1), Ni(deamp) ₂ (2), and Ni(emamp)₂ (3), were synthesized by the metathesis reaction between [Ni(NH₃)₆]Cl₂ and two equiv. of Na(dmamp), Na(deamp), and Na(emamp), respectively. Complexes 1-3 have been characterized by IR, ¹H NMR, and ¹³C NMR spectroscopies, and microanalytical data, as well as single-crystal X-ray diffraction studies. Through GC/MS analysis of the gaseous species generated by the decomposition of 1, a self-reduction pathway to form metallic Ni was studied. By the metalorganic chemical vapor deposition of 1, metallic Ni hexagonal-phase thin films were obtained at 250 °C and cubic-phase thin films were obtained at 400 °C.

Full text of DOI:10.1002/ejic.201001132

FULL PAPER
DOI: 10.1002/ejic.201001132
Synthesis and Characterization of Nickel(II) Aminoalkoxides: Application to
Molecular Precursors for MOCVD of Ni Thin Films
Seung Ho Yoo,[a] Hana Choi,[a] Hyo-Suk Kim,[a] Bo Keun Park,[a] Sun Sook Lee,[a]
Ki-Seok An,[a] Young Kuk Lee,[a] Taek-Mo Chung,[a] and Chang Gyoun Kim*[a]
Keywords: Nickel / N,O ligands / Chemical vapor deposition / Thin films
Novel single precursors for Ni, Ni(dmamp)2 (1), Ni(deamp)2
(2), and Ni(emamp)2 (3), were synthesized by the metathesis
reaction between [Ni(NH3)6]Cl2 and two equiv. of Na(d-
mamp), Na(deamp), and Na(emamp), respectively. Com-
single-crystal X-ray diffraction studies. Through GC/MS
analysis of the gaseous species generated by the decomposi-
tion of 1, a self-reduction pathway to form metallic Ni was
studied. By the metalorganic chemical vapor deposition of 1,
metallic Ni hexagonal-phase thin films were obtained at
250 °C and cubic-phase thin films were obtained at 400 °C.
1
plexes 1–3 have been characterized by IR, H NMR, and 13C
NMR spectroscopies, and microanalytical data, as well as
the ligand or H2 necessary as a reducing agents for Ni metal
preparation. Recently, NiNx films were prepared using Ni-
[MeC(NiBu)2]2 as the precursor; Ni films were then formed
by reduction of the NiNx films by annealing in H2 at 160 °C
or with H2 plasma at room temperature.[36] Therefore, it
is necessary that a novel precursor, which is more readily
decomposed and volatile than the well-known nickel pre-
cursors and lessens the incorporation of impurities, should
be designed and synthesized.
MOCVD and ALD methods have been used for various
thin-film materials in the microelectronic area.[37,38] To ap-
ply these methods for thin-film manufacture, adequate pre-
cursors should be prepared, thus it is necessary for the de-
velopment of precursors and the understanding of their
characteristics. Precursors for MOCVD and ALD must be
volatile, transportable, thermally stable at evaporation tem-
peratures, readily decompose at relatively low substrate tem-
peratures, non-toxic, non-corrosive, cheap, and highly
pure.[39–41] Our research has been focused on the develop-
ment of novel precursors for MOCVD and ALD and prep-
aration of metal and metal oxide thin films using these pre-
cursors by MOCVD and ALD techniques.[42–48]
Introduction
Nickel has been used for various thin-film materials,
often alloyed with other elements. Nickel thin films have
been applied as materials for protective coatings against
oxidation and corrosion as decorative and selective absor-
bers.[1] Nickel silicides are in the limelight as a contact mate-
rial in semiconductor devices.[2,3] Nickel oxides can be ap-
plied to p-type transparent conducting films, chemical sen-
sors, electrochromic devices, and resistive random access
memory (ReRAM) devices due to their optical, electrical,
and magnetic properties.[4–8] Nickel sulfides and nickel sele-
nides as p-type semiconductors and nickel phosphides as an
n-type semiconductor are useful for electrodes in photoelec-
trochemical storage devices.[9,10] Various nickel-based alloys
as thin films can be used in catalysts, optical materials, mag-
netic materials, hydrogen storage, resistive and thermoelec-
tric devices, and micro/nano-electromechanical sys-
tems.[11–22]
Nickel films have been deposited by metalorganic chemi-
cal vapor deposition (MOCVD) or atomic layer deposition
(ALD) processes with precursors such as Ni(CO)4,[23–25]
nickelocenes,[26–29] nickel(II) β-diketonate complexes,[30–33]
and Ni[MeC(NiPr)2]2.[34,35] These precursors suffer from
toxicity, low vapor pressure, poor thermal stability, and in-
corporation of impurities such as oxygen or carbon from
In this work, we synthesized novel NiII aminoalkoxide
complexes using various dialkylamino alcohols ligands,
namely, 1-(dimethylamino)-2-methyl-2-propanol (dmampH),
1-(diethylamino)-2-methyl-2-propanol (deampH), and 1-
(ethylmethylamino)-2-methyl-2-propanol (emampH), and
characterized each by spectroscopic methods and X-ray sin-
gle crystallography. From our preliminary CVD studies, the
nickel aminoalkoxide complexes were appropriate as pre-
cursors for the deposition of nickel films without external
reducing agents such as hydrogen. To elucidate the CVD
reaction pathway, ex-situ GC/MS experiments of the de-
composed by-products were performed.
[a] Advanced Materials Division, Korea Research Institute of
Chemical Technology,
Yuseong, P.O. Box 107, Daejeon 305-600, South Korea
Fax: +82-42-861-4151
E-mail: cgkim@krict.re.kr
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201001132.
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C. G. Kim et al.
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X-ray Crystal Structures of 1–3
Results and Discussion
The single-crystal X-ray structure of 1 is shown in Fig-
ure 1. The nitrogen and oxygen atoms of the two dmamp
ligands are chelated to the nickel atom of the square-planar
structure in a trans geometry. The nickel atom forms an
inversion center. The bond lengths of Ni1–O1 and Ni1–N1
are 1.837(3) and 1.937(3) Å, respectively, and are very sim-
ilar to those of tetra-coordinated nickel complexes[54] and
slightly longer than those of bis(β-ketoamino)nickel com-
plexes.[55] They are shorter than the metal–atom distances
reported in six-coordinate nickel(II) complexes.[56,57] The
bite angle (87.74(13) Å) of the aminoalkoxide ligand is very
similar to that found for Ni(OCHMeCH2NMe2)2.[49] The
bond angles O1–Ni1–N1 and O1Ј–Ni1–N1 are 87.74(13)°
and 92.26(13)°, respectively, which are closed to the ideal
90° of a square plane. The two dmamp ligands and the
nickel atom form a two five-membered ring metalacycle; the
rings are composed of Ni1–O1–C1–C2–N1 and Ni1–O1Ј–
C1Ј–C2Ј-N1Ј. These two five-membered rings have enve-
lope conformations in which the C1 and C1Ј atoms, each
coordinating two methyl groups, are located out of the Ni1–
O1–C2–N1 and Ni1–O1Ј–C2Ј–N1Ј planes, respectively.
Synthesis and Characterization of 1–3
As shown in Scheme 1, the nickel(II) aminoalkoxides
were synthesized by the metathesis reaction between
[Ni(NH3)6]Cl2 and two equiv. of the sodium aminoalk-
oxides; all complexes were purified by sublimation (1:
70 °C, 2: 70 °C, and 3: 45 °C at 10–2 Torr). This reaction is
similar to the synthesis of Ni(dmap)2 (dmap = 1,2-dimeth-
ylamino-2-propoxide), which is purified by sublimation at
93–95 °C at 10–2 Torr.[49] The complexes were highly soluble
in organic solvents such as THF, Et2O, and toluene and
1
were characterized by a combination of FT-IR, H NMR,
and 13C NMR spectroscopies, elemental analysis, MS spec-
trometry, and X-ray single crystallography. Mass spectro-
metric data of all complexes displayed only monomeric
fragments such as [Ni(L)2]+ and [Ni(L)1]+ species. On the
basis of mass data, we inferred that the complexes were
monomers with four-coordinate metal spheres, which was
confirmed by X-ray single crystallographic analysis.
Scheme 1. Synthesis of complexes 1–3.
The melting points of the complexes were measured by
a melting point apparatus (model No. SMP3 manufactured
by Bibby Sterilin) and appear at 118–120 °C for 1, 52–53 °C
for 2, and 75–76 °C for 3. The melting points of the com-
plexes are lower than NiCp2 (173 °C),[50] Ni(acac)2
(240 °C),[51] Ni(tmhd)2 (228 °C),[52] and Ni(hfac)2
(207 °C).[53] The melting point of Ni[MeC(NiPr)2]2 (69 °C)[34]
is higher than that of 2 and lower than those of 1 and 3.
On the other hand, the melting point of 1 is higher than
that of Ni[MeC(NiBu)2]2 (87 °C).[36] The melting points of
1–3 were generally at lower temperature than known com-
plexes except for those of few Ni precursors. The 1H NMR
Figure 1. Molecular structure of 1. Selected bond lengths [Å] and
angles [°]: Ni(1)–O(1) 1.837(3), Ni(1)–N(1) 1.937(3), O(1)–C(1)
1.390(5), N(1)–C(2) 1.491(5), C(1)–C(2) 1.552(6); O(1)–Ni(1)–N(1)
87.74(13), O(1Ј)–Ni(1)–N(1) 92.26(13).
The molecular structures of 2 (Figure 2) and 3 (Figure 3)
spectrum of 1 showed three singlets at δ = 1.38 [-OC- are similar to that of 1. The structure of 2 includes two
(CH3)2-], 1.73 [-CH2N(CH3)2], and 2.32 ppm [-CH2N- independent molecules (A and B) in an asymmetric unit;
(CH3)2]. These peaks are shifted by 0.2–0.3 ppm compared the Ni–O distances range from 1.8312(19) to 1.8433(18) Å
with those of dmampH (δ = 1.12, 2.04, and 2.12, respec- and the Ni–N distances range from 1.951(2) to 1.955(2) Å.
tively). The 13C NMR spectrum of 1 has peaks present at δ The Ni–O–N angles are in the range 88.11(9)–92.40(8)°.
= 32.6 [-OC(CH3)2-], 51.5 [-CH2N(CH3)2], 73.6 [-OC- The bite angles are 88.57(9) and 88.39(8)° (molecule A),
(CH3)2-], and 78.3 ppm [-CH2N(CH3)2] compared with and 88.11(9) and 88.16(9)° (molecule B). In 3, the Ni–O
dmampH (28.3, 48.2, 69.8, and 70.2, respectively).[54] The and Ni–N distances are 1.8434(9) and 1.9493(11) Å, respec-
1H NMR spectrum of 2 showed two broad methylene peaks tively. The Ni–O–N angles are 88.26(5)° (O1–Ni1–N1) and
{2.43 [-N(CH2CH3)2] and 3.01 [-N(CH2CH3)2]}, whereas 91.74(5)° (O1Ј–Ni1–N1), and the bite angle is 88.26(5)°.
that of 3 has split broad peaks. These are thought to be due These two complexes also have two envelope conforma-
to relatively slow five-membered ring inversion.
tional five-membered rings. In 2, C1a and C3a (molecule
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Synthesis and Characterization of Nickel(II) Aminoalkoxides
A), and C1b and C3b (molecule B) are located outside
square planar plane. The C1 atom of 3 is also located at
the same position.
Figure 3. Molecular structure of 3. Selected bond lengths (Å) and
angles (°): Ni(1)–O(1) 1.8434(9), Ni(1)–N(1) 1.9493(11), O(1)–C(1)
1.4053(13), N(1)–C(2) 1.4973(14), C(1)–C(2) 1.5391(18); O(1)–
Ni(1)–N(1) 88.26(5), O(1Ј)–Ni(1)–N(1) 91.74(5).
an inversion center at the nickel atom. In complex 2 the
dihedral angle is 0.4°.
Thermal Analysis and Growth of Ni Films
The thermogravimetric analysis (TGA) of 1 is shown in
Figure 4. Weight loss begins at 100 °C and is completed by
170 °C. Differential thermal analysis (DTA) shows an endo-
thermic peak at 127 °C, attributed to the melting of 1. An
endothermic peak at 174 °C, accompanied by a weight loss
(93%) is regarded as evaporation temperature of the com-
plex.
Figure 2. Molecular structure of 2: a) molecule A and b) molecule
B. Selected bond lengths [Å] and angles (°): molecule A: Ni(1A)–
O(2A) 1.8312(19), Ni(1A)–O(1A) 1.8317(18), Ni(1A)–N(1A)
1.951(2), Ni(1A)–N(2A) 1.952(2), O(1A)–C(1A) 1.403(3), N(1A)–
C(2A) 1.495(3), C(1A)–C(2A) 1.530(4); O(2A)–Ni(1A)–O(1A)
178.84(10), O(2A)–Ni(1A)–N(1A) 91.60(9), O(1A)–Ni(1A)–N(1A)
88.57(9), O(2A)–Ni(1A)–N(2A) 88.39(8), O(1A)–Ni(1A)–N(2A)
91.46(8), N(1A)–Ni(1A)–N(2A) 179.31(9); molecule B: Ni(2B)–
O(1B) 1.8388(18), Ni(2B)–O(2B) 1.8433(18), Ni(2B)–N(1B)
1.955(2), Ni(2B)–N(2B) 1.954(2), O(1B)–C(1B) 1.405(3), N(1B)–
C(2B) 1.505(3), C(1B)–C(2B) 1.543(4); O(2B)–Ni(2B)–O(1B)
179.36(9), O(2B)–Ni(2B)–N(1B) 92.40(8), O(1B)–Ni(2B)–N(1B)
88.11(9), O(2B)–Ni(2B)–N(2B) 88.16(8), O(1B)–Ni(2B)–N(2B)
91.33(9), N(1B)–Ni(2B)–N(2B) 179.24(9).
Figure 4. Thermal analysis of complex 1.
The TGA of 2 and 3 exhibit weight losses that begin at
about 100 °C and are complete by 200 °C (Figure 5). The
Complexes 1 and 3 have a dihedral angle of 0° between amounts of the residues were 6% for 1, and 20% each for
the Ni1–O1–N1 plane and the Ni1–O1Ј–N1Ј plane due to 2 and 3. The residual materials of the complexes were
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C. G. Kim et al.
FULL PAPER
thought to be oxidized materials, which were caused by ex- age resulting in intermediate D and acetone. The next step
posure to air during the thermal experiments. The thermal is the ring opening of C by the attack of D, and then
property of 1 is better than those of 2 and 3. TGA data of N,N,NЈ,NЈ-tetramethylethylene-1,2-diamine and acetone are
Ni(acac)2, Ni(acac)2(en), and Ni(tmhd)2 show weight losses induced by C–C cleavage. On the other hand, in B,
at 120–250, 170–280, and 140–200 °C, respectively, and resi- dmampH and pure Ni metal are produced by reductive eli-
dues of 20.9, Ͻ1, and 4%.[58,59] Weight loss in Ni[MeC- mination.
(NiPr)2]2 and Ni[MeC(NiBu)2]2 begin at about 100 °C and
are complete by about 200 °C.[36] The amounts of residues
were about 15 and Ͻ 1%, respectively. Volatility and ther-
mal stability of 1 is better or similar compared with nicke-
l(II) β-diketonates and nickel(II) amidinates complexes,
therefore 1 is suitable as a MOCVD precursors to prepare
metallic nickel thin films.
Scheme 2. Thermal decomposition products of complex 1.
Figure 5. Comparison of thermogravimetric analysis of complexes
1–3.
As a result of our preliminary CVD experiments, metallic
nickel thin films were deposited from our precursors with-
out using any reducing agent. Therefore, we thought that
the growth of Ni films from 1 occurred through the self-
reduction of the precursor. Unlike nickelocene or nickel(II)
β-diketonate complexes, which require H2 as a reducing
agent for Ni metal preparation,[26–33] the NiII aminoalk-
oxides can be applied to deposit metallic Ni films without
any reducing agents by a self-reduction reaction of the pre-
cursors at moderately low temperature. To elucidate the de-
Scheme 3. Proposed thermal decomposition mechanism of complex
1.
composition reaction pathway, we examined the gas phase
The Ni thin films deposited on SiO2/Si(100) substrates
by-products from the decomposition of 1. The complex was by MOCVD using precursor 1 at 250 °C and 400 °C were
decomposed in a tube furnace, which was filled with frag- examined by XRD and SEM. The XRD patterns show
ments of Si, and the decomposed gaseous products were three peaks assigned to (010), (002), and (011) planes of
collected in a liquid-nitrogen trap located between the fur- hexagonal phase (JCPDS 45–1027) for the Ni thin films
nace and the pump. Analysis of the accumulated gaseous grown at 250 °C. In the films grown at 400 °C, two peaks
species by GC/MS revealed the presence of acetone, corresponding to (111) and (200) planes of cubic phase
dmampH, and N,N,NЈ,NЈ-tetramethylethylene-1,2-diamine (JCPDS 04-0850) were observed (Figure 6).
(Scheme 2). The gaseous species are the as same those of
The SEM images of the Ni thin films grown at 250 and
the Cu(dmamp)2. Hence, the proposed mechanism of form- 400 °C are shown in Figure 7. The image for the 250 °C
ing metallic nickel films from 1 is thought to be identical sample exhibits multiform shapes and various sized crystal-
to that of Cu(dmamp)2.[42] The proposed reaction pathway line grains, whereas the 400 °C sample shows crystalline
is shown in Scheme 3. The first step is the γ-hydrogen elimi- grains of various forms and a size distribution larger than
nation of dmamp ligand to form the intermediates A and that seen for the films grown at 250 °C.
B. Intermediate A can then take one of two possible path-
XPS of a Ni film deposited from 1 on Si(111) at 250 °C
ways. The first is the cyclization of the oxygen atom to pro- showed the Ni 2p1/2, 2p3/2, 3s, 3p peaks, O 1s peak, and C
duce the epoxide intermediate C. The other is a C–C cleav- 1s peak (Figure S1). XPS of a film deposited at 400 °C
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Synthesis and Characterization of Nickel(II) Aminoalkoxides
MOCVD, hexagonal-phase Ni thin films were obtained at
250 °C, and cubic-phase Ni thin films were formed at
400 °C.
Experimental Section
General: All manipulations were performed under a dry, oxygen-
free nitrogen or argon atmosphere using standard Schlenk tech-
niques or in a glove box. All solvents were distilled under nitrogen
from sodium/benzophenone prior to use. [D6]Benzene and nicke-
l(II) chloride hexahydrate were purchased from Aldrich and used
without further purification. Nickel hexamine dichloride was pre-
pared as reported in literature.[60] Functionalized bidentate
Figure 6. XRD patterns of Ni thin films grown from complex 1 at
250 °C and 400 °C.
alcohols,
such
as
1-(dimethylamino)-2-methyl-2-propanol
[dmampH, (CH3)2NCH2C(CH3)2OH], 1-(diethylamino)-2-methyl-
2-propanol [deampH, (CH3CH2)2NCH2C(CH3)2OH], and 1-(ethyl-
methylamino)-2-methyl-2-propanol [emampH, (CH3CH2)(CH3)-
NCH2 C(CH3)2OH] were synthesized by modified methods of ref-
erences[54,61] and dried under nitrogen prior to use. 1H and 13C
NMR spectra were recorded at 300 MHz on a Bruker DPX
300 MHz FT NMR spectrometer. All samples for NMR spec-
troscopy were contained in sealed NMR tubes and referenced using
[D6]benzene as internal standard. Infrared (IR) spectra were ob-
tained with a Nicolet NEXUS FT-IR Spectrometer in a 4 mm KBr
window or pellet with KBr. The samples were prepared in a glove
box. Elemental analyses were performed by Thermoquest EA-1110
CHNS analyzer. Mass spectra were obtained on an Autospec mass
spectrometer for electron impact (EI) mass spectra.
Synthesis of Nickel Aminoalkoxides Ni(OCMe2CH2NRRЈ)2 [R = RЈ
= Me (1); R = RЈ = Et (2); R = Me, RЈ = Et (3)]: The sodium salt
of the amino alcohols (2 equiv.) [Na(dmamp) 2.37 g, 17.0 mmol
(1); Na(deamp) 2.84 g, 17.0 mmol (2); Na(emamp) 2.60 g,
17.0 mmol (3)] was slowly added to a suspension of [Ni(NH3)6]Cl2
(1.50 g, 8.5 mmol) in toluene (30 mL) and stirred under reflux for
8 h. After cooling, the reaction mixtures were filtered off and crude
products were obtained by removal of all volatilities under vacuum.
Figure 7. SEM images of Ni thin films grown from complex 1 at a)
250 °C and b) 400 °C.
showed the same peaks (Figure S2), however, the O 1s and
C 1s peaks were of lesser intensity than those of film de-
posited at 250 °C. The film contained noticeable oxygen im- Analytically pure products were obtained by sublimation.
purity, which is thought to be a contamination due to expo-
sure of the sample to ambient conditions after the deposi-
tion process.
Ni(dmamp)2 (1): Yield 2.17 g (88%), m.p. 118–120 °C. Sublimed at
1
70 °C (10–2 Torr). H NMR (300 MHz, C6D6): δ = 1.38 [s, 12 H,
-OC(CH3)2-], 1.73 [s, 4 H, -CH2N(CH3)2], 2.32 [s, 12 H, -CH2N-
(CH3)2] ppm. 13C NMR (75.7 MHz, C6D6): δ = 32.6 [-OC(CH3)2-],
51.5 [-CH2N(CH3)2], 73.6 [-OC(CH3)2-], 78.3 [-CH2N(CH3)2] ppm.
FT-IR (KBr): ν = 2963 (s), 2911 (m), 2859 (m), 1467 (m), 1455
˜
Conclusion
(m), 1438 (m), 1393 (w), 1367 (m), 1347 (m), 1295 (m), 1243 (w),
1195 (m), 1159 (m), 1112 (m), 1018 (m), 996 (m), 978 (m), 942 (s),
900 (w), 843 (m), 789 (w), 674 (s), 552 (w), 527 (w), 484 (w), 454
(w). MS: m/z (I%): 290 (39) [Ni(dmamp)2], 275 (7) [Ni(dmamp)2-
CH3], 174 (100) [Ni(dmamp)], 159 (21) [Ni(dmamp)-CH3], 116 (30)
[Ni(dmamp)-CH2N(CH3)2], 58 (77) [dmamp-CH2N(CH3)2].
C12H28N2NiO2 (291.08): calcd. C 49.52, H 9.70, N 9.62; found C
49.08, H 9.45, N 9.47.
We have synthesized new NiII aminoalkoxide complexes,
Ni(dmamp)2 (1), Ni(deamp)2 (2), and Ni(emamp)2 (3). By
thermal analysis, the Ni complexes showed high volatility.
Melting points of the precursors decreased as the bulky
alkyl groups on the nitrogen atom were substituted. The
molecular structures of 1–3 reveal a square planar environ-
ment of Ni with the binding of two oxygen atoms and two
nitrogen atoms in trans geometries. By TGA, the thermal
properties of 1 are better than those of 2 and 3 and similar
to known Ni precursors. Ni thin films were grown by the
self-reduction of 1. Through a GC/MS study of the gener-
ated gases during decomposition of 1, the reaction shows
the production of acetone, dmampH, and N,N,NЈ,NЈ-tetra-
methyl-ethene-1,2-diamine with nickel metal. Through the
analysis the reaction pathway was proposed, metallic Ni is
Ni(deamp)2 (2): Yield 2.32 g (79%), m.p. 52–53 °C. Sublimed at
1
70 °C (10–2 Torr). H NMR (300 MHz, C6D6): δ = 1.34 [s, 12 H,
-OC(CH3)2-], 1.68 [s, 12 H, -N(CH2CH3)2], 1.87 [s, 4 H, -CH2N-
(CH2CH3)2], 2.43 [br., s, 4 H, -N(CH2CH3)2], 3.01 [br., s, 4 H,
-N(CH2CH3)2] ppm. 13C NMR (75.7 MHz, C6D6): δ = 11.5
[-N(CH2CH3)2], 34.0 [-OC(CH3)2-], 52.7 [-CH2N(CH2CH3)2], 67.1
[-N(CH CH ) ], 73.3 [-OC(CH ) -] ppm. FT-IR (KBr): ν = 2971
˜
2
3 2
3 2
(s), 2916 (m), 1459 (m), 1390 (m), 1371 (m), 1346 (m), 1282 (w),
1212 (m), 1171 (s), 1141 (m), 1080 (m), 1053 (m), 1032 (m), 971
formed by γ-elimination and then reductive elimination. By (w), 901 (w), 786 (m), 674 (m), 592 (w), 532 (w), 444 (w), 419 (w).
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MS: m/z (I%): 346 (15) [Ni(deamp)2], 230 (25) [Ni(deamp)2-
Thermal Analysis: Thermogravimetric analyses and differential
CH2N(CH2CH3)2-2CH3], 202 (39) [Ni(deamp)], 130 (44) [deamp- thermal analyses (TGA/DTA) for the newly synthesized complexes
CH3], 86 (100) [deamp-2CH2CH3], 58 (45) [deamp-
CH2N(CH2CH3)2]. C16H36N2NiO2 (347.18): calcd. C 55.35, H
10.45, N 8.07; found C 50.95, H 9.69, N 8.60.
were investigated by Perkin–Elmer TGA7 apparatus. The TGA
data of the complexes were obtained up to 800 °C at a heating rate
of 10 °C/min under atmospheric pressure with N2 as carrier gas.
Ni(emamp)2 (3): Yield 2.22 g (82%), m.p. 75–76 °C. Sublimed at
Film Deposition: Ni thin films were grown on SiO2/Si(100) sub-
1
45 °C (10–2 Torr). H NMR (300 MHz, C6D6): δ = 1.18, 1.62 [br. strates by MOCVD using Ni(dmamp)2. Si(100) substrates were
s, 12 H, -OC(CH3)2-], 1.72 (br. s, 6 H, -NCH2CH3), 1.44, 2.07 [br. treated with piranha solution (H2SO4/H2O2 = 4:1) for 20 min and
d, 4 H, -CH2N(Me)(Et)], 1.94, 2.89 (br. s, 4 H, -NCH2CH3), 2.54 then rinsed several times with deionized water before loading. The
(br. s, 6 H, -NCH3) ppm. 13C NMR (75.7 MHz, C6D6): δ = 11.9,
12.0 (-NCH2CH3), 32.3, 32.6, 34.3, 34.6 [-OC(CH3)2-], 48.8, 49.3
base pressure of the deposition chamber was 2 ϫ 10–5 Torr and the
working pressure was increased to 3.5 ϫ 10–2 Torr during the film
(-CH2NCH3), 56.2, 56.4 (-NCH2CH3), 72.8, 73.0 [-OC(CH3)2-], deposition with Ar as carrier gas. The temperature of the precursor
73.6, 73.7 (-NCH ) ppm. FT-IR (KBr): ν = 2963 (s), 2911 (m),
vessel was maintained at 70 °C. The substrate temperature was con-
˜
3
2859 (m), 1467 (m), 1455 (m), 1438 (m), 1393 (w), 1367 (m), 1347 trolled at 250 and 400 °C. The surface morphology of the films was
(m), 1295 (m), 1243 (w), 1195 (m), 1159 (m), 1112 (m), 1018 (m), characterized by AFM (Nanoscope IV, Digital Instrument). X-ray
996 (m), 978 (m), 942 (s), 900 (w), 843 (m), 789 (w), 674 (s), 552
(w), 527 (w), 484 (w), 454 (w). MS: m/z (I%): 318 (62)
[Ni(emamp)2], 303 (7) [Ni(emamp)2-CH3], 202 (75) [Ni(emamp)2-
CH2N(Me)(Et)-CH2CH3–CH3] 188 (93) [Ni(emamp)], 173 (23)
diffraction (XRD) with the Cu-Kα radiation (λ = 1.541838 Å) was
employed to investigate the crystallinity of the films.
Supporting Information (see footnote on the first page of this arti-
cle): XP survey spectra of Ni film deposited on Si(111) at 250 and
400 ºC with 1.
[Ni(emamp)-CH3],
72
(100)
[emamp-N(CH2CH3)(CH3)].
C14H32N2NiO2 (319.13): calcd. C 52.69, H 10.11, N 8.78; found C
48.94, H 9.69, N 7.98.
Acknowledgments
Crystal Structure Determination: Single crystals of the complexes
were obtained from a saturated toluene solution of 1 at –30 °C, a
saturated n-hexane solution of 2 at –30 °C or an n-hexane solution
of 3 in a glass tube under reduced pressure. All of the crystals were
subsequently mounted in thin-walled glass capillaries under Ar at-
mosphere that were sealed as a precaution against moisture/air sen-
sitivity. Data collection for the crystals were performed on a Sie-
mens SMART CCD equipped with a graphite crystal and incident-
beam monochromator. The solutions of all structures were carried
out by a combination of direct methods and Fourier techniques
using SHELXTL program package[62] and refined by full-matrix
least square methods based on unique reflection using SHELXL-
97[62,63] with anisotropic temperature factors for all non-hydrogen
atoms. Details of crystallographic data for 1–3 are summarized in
Table 1.
This research was supported by the Converging Research Center
Program through the Ministry of Education, Science and Technol-
ogy (2010K000976)
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1
2
3
Formula
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C12H28N2NiO2 C16H36N2NiO2 C14H32N2NiO2
monoclinic
P21/n
5.8570(10)
18.108(2)
7.6710(10)
90
111.07(2)
90
monoclinic
P21/c
18.950(6)
15.519(5)
13.997(5)
90
110.522(7)
90
3855(2)
8
1.196
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9111
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monoclinic
P21/n
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8.516(5)
90.000(5)
108.393(5)
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819.8(9)
4
1.293
1.185
5115
1926
α [°]
β [°]
γ [°]
V [A3]
759.18(18)
2
1.273
Z
dcalcd [gcm–3]
μ [mm–1]
1.272
Reflections collected 1427
Unique reflections
R1 [IϾ2σ(I)][a]
wR2 (all data)[b]
GOF
1327
0.0525
0.1402
1.027
0.0210
0.0577
1.062
[a] R1 = (Σ||Fo| – |Fc||)/Σ|Fo|. [b] wR2 = [Σ w(Fo – Fc2)2/Σ w(Fo ) ]
.
2
2 2 1/2
CCDC-796451 (for 1), -796450 (for 2), and -796452 (for 3) contain
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Received: October 23, 2010
Published Online: March 1, 2011
Eur. J. Inorg. Chem. 2011, 1833–1839
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1839