Synthesis, characterization and luminescence study of dialkyl[1- arylmethyleneimino-2-naphthonato]gallium complexes: Crystal structure of dimethyl[1-(2-pridyl) methyleneimino-2-naphthonato]gallium

Article abstract of DOI:10.1016/j.jorganchem.2005.11.074

Eight dialkylgallium complexes of type R₂GaL [(M = Me, L = 1-(2-pyridyl)methyleneimino-2-naphthonato (1), M = Et, L = 1-(2-pyridyl) methyleneimino-2-naphthonato (2), M = Me, L = 1-phenylmethyleneimino-2- naphthonato (3), M = Et, L = 1-phenylmethyleneimino-2-naphthonato (4), M = Me, L = 1-(p-methoxylphenyl)methyleneimino-2-naphthonato (5), M = Me, L = 1-(3,4-dimethoxylphenyl)methyleneimino-2-naphthonato (6), M = Me, L = 1-naphthylmethyleneimino-2-naphthonato (7), M = Me, L = 1- naphthylmethyleneimino-2-naphthonato (8)) have been synthesized by reaction of trialkylgallium with appropriate 1-arylmethyleneimino-2-naphthols. The complexes have been characterized by elemental analysis, ¹H NMR, IR and mass spectrometry. Structure of dimethyl[1-(2-pyridyl)methyleneimino-2-naphthonato] gallium (1) has been determined by X-ray single crystal analysis. Ga atom is five coordinate in the structure. Photoluminescent properties have been measured. The maximum emission wavelengths are in the range of 358 and 412 nm with the intensity of 13-325 a.u. The electroluminescent properties of 3, 5, 7 and 8 have been measured. The maximum emission wavelengths are in the range of 450 and 480 nm.

Full text of DOI:10.1016/j.jorganchem.2005.11.074

Journal of Organometallic Chemistry 691 (2006) 1817–1824
www.elsevier.com/locate/jorganchem
Synthesis, characterization and luminescence study of
dialkyl[1-arylmethyleneimino-2-naphthonato]gallium
complexes: Crystal structure of dimethyl[1-(2-pridyl)
methyleneimino-2-naphthonato]gallium
a,b,
b
c
b,
*
Yingzhong Shen
*, Hongwei Gu , Yu Zhu , Yi Pan
a
Applied Chemistry Department, School of Material Science and Technology, Nanjing University of Aeronautics and Astronautics,
Yudao Street 29#, Nanjing, Jiangsu 210016, PR China
b
Department of Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China
c
Analysis Center of Zhengzhou University, Zhengzhou 450052, PR China
Received 27 April 2005; received in revised form 13 November 2005; accepted 22 November 2005
Available online 14 February 2006
Abstract
Eight dialkylgallium complexes of type R2GaL [(M = Me, L = 1-(2-pyridyl)methyleneimino-2-naphthonato (1), M = Et, L =
1-(2-pyridyl)methyleneimino-2-naphthonato(2),M = Me,L = 1-phenylmethyleneimino-2-naphthonato(3),M = Et,L = 1-phenylmethyl-
eneimino-2-naphthonato (4), M = Me, L = 1-(p-methoxylphenyl)methyleneimino-2-naphthonato (5), M = Me, L = 1-(3,4-dimethoxyl-
phenyl)methyleneimino-2-naphthonato (6), M = Me, L = 1-naphthylmethyleneimino-2-naphthonato (7), M = Me, L = 1-naphthylme-
thyleneimino-2-naphthonato (8)) have been synthesized by reaction of trialkylgallium with appropriate 1-arylmethyleneimino-2-naphthols.
1
The complexes have been characterized by elemental analysis, H NMR, IR and mass spectrometry. Structure of dimethyl[1-(2-pyr-
idyl)methyleneimino-2-naphthonato]gallium (1) has been determined by X-ray single crystal analysis. Ga atom is five coordinate in
the structure. Photoluminescent properties have been measured. The maximum emission wavelengths are in the range of 358 and
412 nm with the intensity of 13–325 a.u. The electroluminescent properties of 3, 5, 7 and 8 have been measured. The maximum emission
wavelengths are in the range of 450 and 480 nm.
ꢀ 2006 Published by Elsevier B.V.
Keywords: Trialkylgallium; Electroluminescent; X-ray crystal structure
1. Introduction
developed as luminescent materials including small molec-
ular systems and aromatic organic polymer [3–6]. Organo-
metallic complexes are very promising candidates as
emitting materials in the OLEDs. Although quite a few
metallic complexes such as 8-hydroxyquinoline or azome-
thine coordinated Al(III), Be(II), Zn(II) complexes have
been studied [7–10], few group 13 organometallic com-
plexes-based electroluminescent diodes were known
[11,12]. So development of various electroluminescent
materials and study the relationship between structure
and electroluminescence property are in great need.
Recently, we reported some light-emitting materials based
on group 13 organometallic complexes [13–16]. In order
Since the first observation of electroluminescence (EL)
in 1965 [1], EL devices have been extensively studied due
to their potential application to fullcolor flat panel dis-
plays, a high performance device fabricated by Tang and
VanSlyke using two-layer light-emitting diodes (LEDS)
with organic fluorescent dyes was a breakthrough in this
field [2]. Then a number of organic materials have been
*
Corresponding authors. Tel.: +86 25 84896019; fax: +86 25 84892951.
E-mail address: syz_msc@nuaa.edu.cn (Y. Shen).
0022-328X/$ - see front matter ꢀ 2006 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2005.11.074

1818
Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
Table 1
Synthesis of complexes 1–8
to search for the new electroluminescent materials, we
report here the synthesis and characterization of various
dialkyl[1-arylmethyleneimino-2-naphthonato]gallium com-
plexes, Both the photoluminescent and electroluminescent
properties of the complexes have been measured and dis-
cussed as well.
Compound number
R
Ar
1
2
3
4
5
6
7
8
Me
Et
2-Pyridyl
2-Pyridyl
Me
Et
Phenyl
Phenyl
Me
Me
Me
Me
p-Methoxylphenyl
3,4-Dimethoxylphenyl
1-Naphthyl
9-Anthryl
2. Results and discussion
2.1. Synthesis and characterization
Reaction of 1-arylmethyleneimino-2-naphthols, which
were obtained by condensation of 1-amino-2-naphthol
with 2-pridylaldehyde, benzaldehyde, p-methoxybenzalde-
hyde, 3,4-dimethoxy-benzaldehyde, 1-naphthalaldehyde
and 9-anthralaldehyde, with trimethyl- or triethylgallium
proceeded smoothly at room temperature and afforded
the corresponding dialkylgallium complexes in almost
quantitative yields (Schemes 1, 2 and Table 1). The com-
plexes isolated are deep red or brown solids. Although tri-
alkylgallium is extremely moisture and oxygen sensitive,
the complexes obtained are fairly stable on exposure to
air and they could be left in ambient atmosphere for
months without obvious decomposition. The complexes
are nearly insoluble in cold saturated hydrocarbons such
as pentane or petroleum and are fairly soluble in unsatu-
rated hydrocarbons such as benzene or toluene. All the
products obtained gave satisfactory elemental analysis
results as expected for the stoichiometric structure
R2GaL. The compounds obtained have been characterized
groups and the disappearance of O–H vibration compar-
ing with the free ligands prove the reaction of trialkylgal-
lium with the hydroxyl group of the ligands. The stretch
vibration of C@N bond appeared at higher frequency
than those of the free ligands, suggesting in some extent
the coordination of imino nitrogen atom to the gallium
metal. The chemical shifts of the gallium–bonded methyl
1
or methylene protons in their H NMR spectra appeared
at higher field compared with those of the free gallium tri-
alkyls, implying the coordination of the nitrogen atom to
gallium, as the coordination of nitrogen atom to gallium
should increase the electron density around the metal cen-
ter. The molecule ion peaks of the complexes were all vis-
ible in their MS spectra and the fragments eliminating one
methyl or ethyl group appeared in high intensity. The rel-
ative intensity of the gallium-containing peaks in the MS
spectra agrees well with the isotopic distribution of the
gallium atom [69Ga (ca. 60%); 71Ga(ca. 40%)]. These indi-
cate that the complexes exist as intramolecularly coordi-
nated monomeric species.
1
by IR, H NMR and MS spectroscopy, respectively. In
the IR spectra of the complexes, appearance of visible
alkyl C–H vibration from the gallium-bonded alkyl
2.2. Solid-state structure of 1
Single crystals of 1 was obtained by recrystallization of a
saturated benzene solution containing 1 at ꢀ20 ꢁC. The
N
N
R
Ga
N
+
N
GaR3
R
-RH
OH
O
Scheme 1. Synthesis of complexes 1–2.
Ar
HC
Ar
HC
R
Ga
R
N
N
O
OH
+
GaR3
Fig. 1. Molecular structure of 1, showing 50% probability displacement
Scheme 2. Synthesis of complexes 3–8.
ellipsoids. Hydrogen atoms are omitted for clarity.

Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
1819
Table 2
nitrogen, to form another intramolecularly coordinated
five-membered ring. It shows clearly the coordination of
two nitrogen atoms to the gallium with formation of two
new five-membered rings. Gallium atom is five coordinate
in the compound in the geometry of trigonal bipyramidal.
The naphthyl plane and the pyridyl plane are almost copla-
nar connected by a C@N bridge, suggesting that a good con-
jugation p-electrons system is formed in the structure. The
compound exists as a monomer in the solid state, in spite
of quite a few dimethylgallium alkoxides and phenoxides
were found to be dimeric with a planar Ga2O2 ring
Crystal data, collection parameters, and refinements for 1
Formula
Formula weight
Crystal color
Crystal dimensions (mm)
Crystal system
Space group
C18H17GaN2O
347.07
Deep red
1.00 · 0.80 · 0.80
Monoclinic
P21/c (#14)
14.800 (2)
7.344 (5)
15.809 (3)
110.35 (1)
1611.0300
4
1.431
712.00
17.10
RAXIS-IV
Mo Ka (k = 0.71070 A)
288
55.0
2496
˚
a (A)
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
˚
[17–19]. Ga–O1 distance (2.002(4) A) in 1 is longer than
Z value
Dcalc (g/cm3)
F000
l (Mo Ka) (cmꢀ1
Diffractometer
Radiation
Temperature (K)
2hmax (ꢁ)
Number of
reflections measured
Independent reflections
observed (I) > 3.00 (r(I))
Number of variables
Correction
those reported in N,N-ethylenbis(salicylideneiminato)[dim-
˚
ethylgallium] (1.869(2) and 1.874(2) A, respectively) [20],
)
˚
dimethylgallium N-methylsalicylaldiminate (1.904(7) A)
[21] and dimethylgallium[2-(N,N-dimethylaminomethyl)-4-
˚
˚
methyl]phenoxide 1.890(4) A) [22]. The Ga–N distances
˚
˚
(2.303(4) A for Ga–N1 and 2.115(5) A for Ga–N2 are also
longer than those reported for Ga–N covalent and coordi-
native bond lengths as in (a-pyridyl)acetophenone Ga–N
1867
t
˚
˚
(2.027(2) A) [23], Me3GaNH2 Bu (2.12(1) A) [24] and
dimethylgallium-[2-(N,N-dimethylaminomethyl)-4-methyl]-
251
˚
Lorentz polarization
phenoxide (2.096(6) A) [22]. The apparent difference in Ga–
R (F)
wR
0.052
0.077
1.24
O and Ga–N length between the present compound (1) with
other known compounds should be caused by the steric
requirements of formation of the two rigid five-membered
rings.
Goodness-of-fit indicator
ꢀ3
˚
˚
Dqmax (e Aꢀ3
)
0.55
Dqmin (e A
)
ꢀ0.54
(D/r)max
0.00
P
P
P
P
2
1=2
a
R1 ¼ ðkF oj ꢀ jF ckÞ= jF oj; wR2 ¼ ½ ðwðF 2o ꢀ F c2Þ Þ= ðwF o4Þꢁ
.
3. Photoluminescence study
2
b
c
w ¼ 1=½r2ðF 2oÞ þ ð0:00490PÞ ꢁ; P ¼ ðF o2 þ 2F 2c Þ=3.
P
S ¼ ½ wðF 2o ꢀ F c2Þ ꢁ=ðn ꢀ pÞ1=2. n, number of reflections; p, parame-
2
Photoluminescence (PL) emission spectra of the com-
plexes 1–8 were measured as shown in Fig. 2. It shows that
the emission bands are located in ultraviolet to violet-blue
region from 377 to 412 nm and most of them appeared as
multi-peaks. The emission maximum wavelengths and
intensities are summarized in Table 4. The emission
strength of the pyridyl containing complexes is obviously
lower than those of the phenyl- or naphthyl-containing
ones, implying that the electro-withdrawing pyridyl group
is disadvantageous to light-emission. Emission wavelength
ters used.
result of the X-ray structure analysis of 1 is depicted in
Fig. 1. Crystal data, collection and refinement parameters
are summarized in Table 2 and selected bond length (A)
and angles (ꢁ) are given in Table 3. Complex 1 crystallizes
in the monoclinic space group P21/c (#14). In compound
1, the nitrogen atom in the pyridyl group coordinates to
the gallium atom, apart from the coordination of the imino
˚
Table 3
˚
Selected bond distances (A) and angles (ꢁ) for 1
400
350
Bond distances
Ga–O1
Ga–N2
C5–C6
C7–C12
C9–C10
C11–C12
2.002 (4)
2.115 (5)
1.456 (8)
1.451 (7)
1.341 (9)
1.435 (8)
Ga–N1
O1–C8
N1–C5
N2–C7
C7–C8
2.303 (4)
1.303 (6)
1.353 (7)
1.394 (6)
1.412 (7)
(3)
300
250
(7)
(4)
(5)
200
150
100
50
Bond angles
O1–Ga1–N1
Ga1–O1–C8
Ga1–N2–C6
N1–C5–C6
N2–C6–C5
O1–C8–C7
O1–Ga1–N2
(6)
153.2 (2)
N1–Ga1–N2
Ga1–N1–C5
C17–Ga1–N2
C17–Ga1–C18
C1–N1–C5
78.9 (2)
111.5 (3)
112.7 (3)
126.9 (4)
118.3 (5)
112.7 (3)
111.9 (5)
115.0 (3)
117.2 (4)
114.9 (54)
120.0 (5)
121.3 (5)
78.9 (2)
(8)
(2)
(1)
400
wavelength (nm)
0
350
450
500
Ga1–N2–C7
N2–C7–C8
Fig. 2. PL emission spectra of 1–8 in solid state.

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Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
Table 4
employed. High-quality film can be obtained by spin-cast
of PMMA and gallium complexes mixture dissolved in
dichloromethane. An electron injecting electrode Al was
deposited on top by vacuum evaporation at pressure
Wavelength and emission intensity of the complexes 1–8
Compound
number
Wavelength (cmꢀ1) (intensity, a.u.)
below 2 · 10ꢀ5 Torr with a deposition rate of 10–15 A/s.
˚
1
2
3
4
5
6
7
8
385 (13)
396 (23)
The emitting area was 2 · 3 mm2. The luminance of the
EL devices was measured with a Perkin–Elmer LS 50B
fluorescence spectraphotometer. Meanwhile, the current
density was recorded with a digital multimeter. All mea-
surements were carried out at room temperature under
DC bias conditions.
370 (267)
370 (200)
358 (102)
359 (97)
390 (250)
386 (84)
380 (325)
377 (233)
380 (150)
379 (162)
412 (247)
407 (61)
395 (267)
383 (200)
395 (109)
396 (145)
The current–voltage relationship of the EL device is
shown in Fig. 4. The forward bias current can be obtained
when the ITO electrode is positively biased and the Al elec-
trode negatively. The current density, increasing propor-
tional to the bias voltage, increases from 1 to 185 mA/
cm2 for complex 3 (1–18 V), from 1 to 105 mA/cm2 for
complex 5 (1–23 V), from 4 to 206 mA/cm2 for complex 7
(1–16 V), and from 16 to 128 mA/cm2 for complex 8 (1–
30 V). The current density increasing rate for complex 3
and 7 are much larger than those of the complexes 5 and
8, implying that there is a stronger electron interaction
between the molecules in 3 and 7. This is reasonable con-
sidering the nature of substitutes on the phenyl ring or
the coplanarity of the molecules. The break down voltage
is 18, 23, 20 and 30 V for complexes 3, 5, 7 and 8,
respectively.
The EL intensity-voltage relationship of the EL devices
for the complexes 3, 5, 7 and 8 was measured as shown in
Fig. 5. The light output of the EL diodes is proportional to
the input voltage in the voltage range of 8–18 V (3), 18–
23 V (5), 10–20 V (7) and 20–30 V (8). Complexes 5 and
7 exhibit relatively higher EL intensities than the other
two. Good luminescent characteristic of the complex 5
may attribute to the methoxyl group on the phenyl ring.
Steric hindrance of the methyl group decreases electron-
interaction between the molecules, then subdues thermo-
quenching of excitons. For complex 7, it should be due
Al
Emitter Layer
ITO
-
+
Glass
Fig. 3. Configuration of EL cell.
of the compound 7 is longer than that of 8, and the emis-
sion intensity of the compound 7 is also relatively better
than that of 8. The difference in emission wavelengths
and intensities between the compound 7 and 8 should
reflect their difference in structure. Considering the p-sys-
tem of anthryl group is larger than that of the naphthyl
group, the abnormal blue-ward shift of emission wave-
length and the poor emission intensity should imply that
the anthryl group in the compound 8 may not conjugate
very well with other part p-system of the compound. The
poor coplanarity of the compound may be caused by the
steric repellency between the anthryl group and the other
part of the compound. Energy optimized molecular model-
ing shows clearly that the two naphthyl groups in the com-
pound 7 is almost coplanar, while the naphthyl group and
the anthryl group in the compound 8 is impossible to locate
in one plane. There is a strong steric repellency between the
anthryl group and the dimethylgallium group in 8.
4. Electroluminescence study
200
3
5
7
8
Compounds 3, 5, 7 and 8 were selected as light emitting
material. The electroluminescence device structure is
shown in Fig. 3. The gallium complexes were used as
light-emitting layer. The complexes were dissolved in
dichloromethane. The device was prepared on patterned
indium–tin-oxide (ITO) coated on glass substrate, which
was cleaned by ultrasonic in a mixture of isopropanol
and water (1:1) and degreased in toluene vapor, with a
sheet resistance of near 80 X/h . Due to the poor film-
forming properties of the complexes, a very small quantity
of poly(methylmethacrylate) (PMMA), which is inert to
light and electricity, was used to improve the film-forming
properties by mixing it with the organogallium complexes.
150
100
50
0
0
5
10
15
20
25
30
Bias voltage (V)
Fig. 4. The relationship of current density and voltage of diodes with the
A
device structure of ITO/emissive layer/Al was
emitter of complexes 3, 5, 7 and 8.

Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
1821
to gallium atom increases the rigidity of the complexes,
thus reduces the loss of energy via vibration motions, i.e.,
thermo-quenching process and then increases the emission
efficiency.
250
200
150
100
50
3
5
7
8
5. Experimental
5.1. General comments
All reactions were performed in a glove box under puri-
fied nitrogen. The solvents were refluxed with sodium ben-
zophenone and distilled under nitrogen prior to use. The
Schiff-base ligands were prepared by condensation of sal-
icylaldehyde with 1-amino-2-naphthol. Trimethylgallium
and triethylgallium were provided by the National 863
Program Advanced Material MO Precursors R&D Center
of China. 1H NMR data were collected on a Bruder ARX-
300 spectrometer with TMS as internal Standard. Infrared
spectra were collected as KBr pellets on a Shimadzu IR
408 instrument. Mass spectra were measured on VG-
ZAB-HS spectrometer (electron impact ionization), lumi-
nescent spectra was determined with Shimadzu F-5000
fluorescence spectrophotometer, Elemental analysis was
performed on a Perkin–Elmer 240C elemental analyzer.
Melting point was observed in sealed capillaries and was
uncorrected.
0
10
15
20
25
30
Bias voltage (V)
Fig. 5. EL intensity–voltage curves the emitter of complexes 3, 5, 7 and 8.
to the large p-delocalized system formed between the two
naphthyls. Lower EL intensity of complex 8 than that of
complex 7 is shown as expected due to the poor coplanarity
of the anthryl plane and the naphthyl plane. The result
demonstrates that the different substitutes on the Schiff-
base ligands have different effect on the EL characteristics
of the EL diodes. The turn-on voltage of complexes 3, 5,
7 and 8 are 8, 18, 10, 20 V, respectively, which are much
lower than that of tri(1,3-diphenyl-1,3-propanediono) of
diodes with monophenathroline)-europium(III) (25 V) [25].
The EL spectra of the complexes 3, 5, 7 and 8 were
shown in Fig. 6. Their emission wavelengths are located
in the blue region from 450 to 478 nm (450, 469, 475 and
478 nm for the complexes 3, 5, 7 and 8, respectively). The
emission wavelengths of the EL diodes are obviously
related to the structure of the ligands. Different substitutes
have different effects on the emission wavelength. The role
of gallium atom for the EL emission is considered to be the
twofold. Firstly, the formation of covalent bonds between
the gallium and oxygen or nitrogen atoms changes the lev-
els of the transition energy. Secondly, the binding of ligand
The photoluminescence (PL), electroluminescence (EL)
and the relative emission intensity were measured with
Shimadzu F-5000 fluorescence spectra-photometer, and
the absorption spectra were measured with Shimadzu
UV2010 spectra-photometer. The current density was
recorded with a digital multimeter.
5.2. Preparation of dimethyl[1-(2-pyridyl)methyleneimino-
2-naphtha onato]gallium (1)
A solution of trimethylgallium (1.15 g, 10 mmol) in
10 mL of cyclohexane was added dropwise over a period
of 10 min with stirring to a solution of 1-(2-pridyl)methyl-
eneimino-2-naphthol (2.48 g, 10 mmol) in 10 mL of cyclo-
hexane and 2 mL of benzene. After stirring the reaction
mixture for an additional 15 min at room temperature,
all volatiles are removed in oil-pump vacuo and the yellow
powder was recrystallized from cyclohexane/benzene solu-
tion, giving cardinal crystals. Yield: 3.1 g (89.3% based on
TMGa).
M.p.: 148–150 ꢁC (dec). Anal. Calc. for C18H17N2OGa:
C, 62.29; H, 4.94; N, 8.07. Found: C, 62.16; H, 4.59; N,
8.15%. IR data (cmꢀ1): 3051 (vw), 2959 (w), 1610 (m),
1595 (s), 1554 (m), 1530 (m), 1502 (s), 1480 (m), 1449
(vs), 1440 (vs), 1390 (m), 1364 (w), 1344 (s), 1311 (m),
1261 (w), 1208 (m), 1150 (s), 1138 (vs), 1081 (w), 1006
(w), 829 (w), 766 (m), 751 (m), 725 (m), 577 (w). 1H
NMR data (ppm): 9.31 (s, 1H, –CH@N) 7.12–8.63 (m,
10H, Ar–H) 0.25 (s, 6H, Ga(CH3)2). MS data: 347.9
(M+, 4.56%), 346.0 (6.72%), 334.0 (13.45%), 333.0
(69.52%), 332.0 (20.37%), 331.0 (100.00%), 317.8 (4.16%),
1.0
3
5
7
0.8
0.6
8
0.4
0.2
0.0
350
400
450
500
550
600
650
Wavenumber (nm)
Fig. 6. EL spectra of diodes with the emitter of complexes 3, 5, 7 and 8.

1822
Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
316.8 (7.97%), 315.9 (6.85%), 314.8 (8.48%), 301.7 (4.23%),
247.0 (19.34%), 239.9 (3.72%), 237.9 (4.85%), 219.0
(3.97%), 100.9 (4.82%), 98.9 (6.52%), 79.0 (1.11%), 78.1
(3.59%), 70.9 (20.82%), 68.9 (31.31%).
5.5. Preparation of diethyl[1-benzylideneimino-2-
naphthonato]gallium (4)
Prepared and purified in the same manner as described
for 1. The compound was isolated as orange crystal. Yield:
3.11 g (82.3% based on TEGa).
5.3. Preparation of diethyl[1-(2-pyridyl)methyleneimino-2-
naphthonato]gallium (2)
M.p.: 180–182 ꢁC. Anal. Calc. for C21H22NOGa: C,
67.42; H, 5.93; N, 3.74. Found: C, 66.43; H, 6.24; N,
3.78%. M.p.: 153–154 ꢁC. IR data (cmꢀ1): 3057 (w), 2934
(m), 2859 (m), 1612 (m), 591 (s), 1574 (m), 1507 (m),
1461 (s), 1429 (m), 1362 (m), 1351 (m), 1283 (s), 1257
(m), 1225 (w), 1000 (m), 817 (m), 809 (m), 759 (m), 745
(m), 729 (m), 691 (w), 643 (m). 1H NMR data (ppm):
8.30 (s, 1H, –CH@N) 7.17–8.01 (m, 11H, Ar–H) 0.94 (q,
4H, GaCH2CH3), 0.43 (t, 6H, GaCH2CH3). MS data:
374.9 (M+, 5.32%), 372.9 (7.74%), 346.9 (15.51%), 345.9
(69.24%), 344.9 (20.88%), 343.9 (100.00%), 317.9 (6.04%),
317.0 (27.34%), 316.0 (11.81%), 315.0 (40.55%), 314.0
(5.48%), 290.6 (5.34%), 288.6 (7.92%), 247.0 (6.62%),
246.0 (26.61%), 211.9 (5.30%), 115.0 (8.70%), 70.9
(53.28%), 68.9 (79.88%).
Prepared and purified in the method as described for
1
from 1-(2-pridyl)methyleneimino-2-naphthol (2.48 g,
10 mmol) and triethylgallium (1.57 g, 10 mmol). The com-
pound was isolated as orange crystal. Yield: 3.05 g (81.5%
based on TEGa).
M.p.: 109–110 ꢁC. Anal. Calc. for C20H21N2OGa: C,
64.04; H, 5.64; N, 7.47. Found: C, 64.25; H, 5.79; N,
7.74%. IR data (cmꢀ1): 3052 (w), 2931 (w), 2895 (w),
2857 (w), 1613 (m), 1594 (m), 1553 (s), 1529 (m), 1504
(s), 1444 (vs), 1393 (m), 1343 (m), 1333 (m), 1311 (m),
1259 (w), 1209 (m), 1147 (m), 1139 (s), 1080 (w), 1006
(w), 829 (w), 764 (m), 741 (m), 557 (m), 499 (w). 1H
NMR data (ppm): 9.34 (s, 1H, –CH@N), 7.14–8.65 (m,
10H, Ar–H), 0.87 (q, 4H, GaCH2CH3), 0.46 (t, 6H,
GaCH2CH3), MS data: 374.8 (M+, 1.05%), 347.9
(13.70%), 346.9 (67.74%), 345.9 (21.59%), 344.8
(100.00%), 332.8 (3.18%), 330.9 (4.73%), 317.9 (7.49%),
316.9 (13.33%), 315.9 (11.08%), 314.9 (14.13%), 291.3
(3.78%), 298.8 (3.37%), 248.0 (6.82%), 247.0 (18.85%),
246.0 (14.27%), 239.9 (5.45%), 237.9 (8.20%), 219.0
(8.89%), 170.0 (5.24%), 115.0 (5.94%), 114.0 (5.71%), 79.0
(4.01%), 70.9 (29.03%), 68.9 (44.33%).
5.6. Preparation of dimethyl[1-(4-methoxy)benzylidene-
imino-2-naphthonato]gallium (5)
Prepared and purified in the same manner as described
for 1 from 1-(4-methoxy)-benzylideneimino-2-naphthol
(2.77 g, 10 mmol) and trimethylgallium (1.15 g, 10 mmol).
The compound was isolated as orange crystal. Yield:
3.16 g (84.1% based on TEGa).
M.p.: 197–198 ꢁC. Anal. Calc. for C20H20NO2Ga: C,
63.87; H, 5.36; N, 3.72. Found: C, 63.87; H, 5.63; N,
3.26%. IR data (cmꢀ1): 3064 (vw), 2969.3 (w), 2959.3 (w),
1614.5 (w), 1592.7 (s), 1571.7 (m), 1511 (vs), 1461 (m),
1422 (w), 1362 (m), 1271 (vs), 1256 (s), 1199 (s), 1173
(w), 1142 (m), 1023 (m), 998 (m), 863 (w), 814 (m), 752
5.4. Preparation of dimethyl[1-benzylideneimino-2-
naphthonato]gallium (3)
Prepared and purified in the same manner as described
for
1
from 1-benzylideneimino-2-naphthol (3.46 g,
1
10 mmol) and trimethylgallium (1.15 g, 10 mmol). The
compound was isolated as orange crystal. Yield: 3.07 g
(88.5% based on TMGa).
(m), 677 (m). H NMR data (ppm): 9.11 (s, 1H, –CH@N),
7.06–7.95 (m, 10H, Ar–H), 3.94 (s, 3H, –OCH3), 0.23 (s,
6H, Ga(CH3)2). MS data: 378.0 (M+, 3.18%), 377.0
(14.68%), 376.0 (5.18%), 374.9 (21.77%), 363.0 (13.87%),
362.0 (67.11%), 361.0 (23.12%), 360.0 (100.00%), 348.1
(6.59%), 347.0 (16.54%), 346.0 (12.03%), 345.0 (23.78%),
344.0 (5.62%), 330.7 (4.17%), 276.9 (12.97%), 275.9
(36.37%), 274.9 (5.44%), 233.0 (6.32%), 211.8 (4.70%),
204.0 (4.27%).
M.p.: 120–121 ꢁC. Anal. Calc. for C19H18NOGa: C,
65.94; H, 5.24; N, 4.05. Found: C, 63.87; H, 5.63; N,
4.06%. IR data (cmꢀ1): 3055 (vw), 2921 (m), 2844 (w),
1617 (w), 1593 (s), 1574 (w), 1508 (m), 1462 (s), 1449 (w),
1430 (w), 1253 (m), 1282 (s), 1256 (s), 1224 (w), 1200 (m),
1001 (m), 853 (vw), 810 (m), 758 (s), 744 (s), 727 (m), 689
1
(m). H NMR data (ppm): 9.31 (s, 1H, –CH@N), 7.17–
8.41 (m, 11H, Ar–H), 0.23 (s, 6H, GaCH3). MS data:
347.9 (M+, 2.57%), 346.9 (12.37%), 345.9 (5.54%), 344.9
(18.03%), 332.9 (13.55%), 332.0 (67.70%), 330.9 (20.52%),
330.0 (100.00%), 317.9 (4.35%), 317.0 (16.45%), 316.0
(10.07%), 315.0 (23.75%), 314.0 (5.80%), 247.0 (15.82%),
246.0 (40.16%), 245.0 (6.26%), 243.9 (5.42%), 242.9
(4.84%), 241.9 (8.12%), 240.9 (6.11%), 228.9 (7.37%),
227.9 (5.31%), 226.9 (11.30%), 225.9 (5.42%), 211.9
(4.03%), 150.9 (4.13%), 115.01 (4.94%), 114.0 (5.68%),
100.9 (14.45%), 98.9 (19.75%), 70.9 (42.11%), 68.9
(63.11%).
5.7. Preparation of dimethyl[1-(3,4-dimethoxy)-
benzylideneimino-2-naphthonato]gallium (6)
Prepared and purified in the same manner as described
for 1 from 1-(3,4-dimethoxy)benzylideneimino-2-naphthol
(3.07 g, 10 mmol) and trimethylgallium (1.15 g, 10 mmol).
The compound was isolated as orange crystal. Yield:
3.51 g (85.1% based on TMGa).
M.p.: 200–201 ꢁC. Anal. Calc. for C21H22NO3Ga: C,
62.21; H, 5.47; N, 3.46. Found: C, 62.42; H, 5.66; N,
3.35%. IR data (cmꢀ1): 3051 (w), 2967 (w), 2900 (w),

Y. Shen et al. / Journal of Organometallic Chemistry 691 (2006) 1817–1824
1823
2833 (w), 1607 (m), 1585 (s), 1547 (w), 1511 (m), 1462 (m),
1429 (w), 1375 (m), 1350 (m), 1315 (m), 1187 (s), 1148 (s),
999 (w), 926 (m), 851 (m), 797 (w), 780 (s), 759 (s). H
(5.08%), 101.0 (5.36%), 198.9 (7.89%), 70.9 (23.34%), 68.9
(35.95%).
1
NMR data (ppm): 9.09 (s, 1H, –CH@N), 7.02–7.96 (m,
9H, Ar–H), 3.99–4.02 (d, 6H, –OCH3), 0.188 (s, 6H,
GaCH3). MS data: 407.1 (M+, 15.05%), 405.2 (21.03%),
393.7 (16.34%), 392.8 (73.37%), 391.8 (24.09%), 390.8
(100.00%), 378.1 (13.84%), 377.0 (10.29%), 376.1
(20.43%), 375.0 (6.11%), 307.1 (10.77%), 306.1 (23.35%),
290.1 (7.06%), 221.0 (4.11%), 100.9 (6.77%), 98.9 (9.50%),
70.9 (17.97%), 68.9 (26.79%).
5.10. Crystal structure determination of compound 1
Single crystal of compound 1 was obtained by recrystal-
lization from benzene solution. A single crystal suitable for
X-ray determination was mounted in a thin-walled capil-
lary tube in a glove box, plugged with resin then flame
sealed. Data were collected at 288 K on a Rigaku-Raxis
IVP imaging plate area detector with graphite monochro-
˚
mated Mo Ka (k = 0.71073 A) radiation to a maximum
5.8. Preparation of dimethyl[1-(1-naphthyl)-
methylenenimino-2-naphthonato]gallium (7)
2h value 55.0ꢁ. Read out was performed in the 0.100 mm
pixel mode. A total of 2496 reflections were collected, the
intensity data were corrected for Lorentz-polarization fac-
tors as well as for absorption. The structure was solved by
direct methods [26] expanded using Fourier technique [27].
All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were included but not refined. All calcula-
tions were performed using the TEXSAN crystallographic
software package of Molecular Structure Corporation [28].
Prepared and purified in the same manner as described
for
1 from 1-(1-naphthyl)-methyleneimino-2-naphthol
(2.97 g, 10 mmol) and trimethylgallium (1.15 g, 10 mmol).
The compound was isolated as orange red crystal. Yield:
3.31 g (83.4% based on TMGa).
M.p.: 116–117 ꢁC. Anal. Calc. for C23H20NOGa: C,
69.74; H, 5.09; N, 3.54. Found: C, 69.94; H, 5.09; N,
3.47%. IR data (cmꢀ1): 3058 (w), 2957 (w), 1685 (w), 1615
(m), 1591 (vs), 1573 (m), 1506 (vs), 1461 (w), 1433 (m),
1371 (m), 1353 (m), 1336 (s), 1162 (vw), 1000 (m), 968 (s),
6. Supplementary material
Crystallographic data (comprising hydrogen atom coor-
dinates, thermal parameters and full tables of bond lengths
and angles) for the structural analysis has been deposited
with the Cambridge Crystallographic Center (Deposition
No. CCDC 269755) Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK, fax: +44 1223
366 033, e-mail: deposit@ccdc.ac.uk or on the web www:
http://www.ccdc.cam.ac.uk.
1
820 (m), 807 (w), 790 (s), 768 (vs), 711 (m), 694 (m). H
NMR data (ppm): 10.04 (s, 1H, –CH@N), 7.2–8.12 (m,
13H, Ar–H), 0.33 (s, 6H, Ga(CH3)2). MS data: 397.1 (M+,
13.52%), 396.1 (5.28%), 395.1 (19.40%), 383.3 (17.09%),
382.4 (70.95%), 381.4 (26.67%), 380.4 (100.00%), 368.4
(5.45%), 367.4 (10.08%), 366.4 (22.54%), 365.4 (14.25%),
364.4 (27.08%), 351.7 (9.31%), 349.9 (7.22%), 348.4
(8.40%), 297.0 (8.67%), 296.0 (31.81%), 115.0 (9.62%),
100.9 (8.40%), 98.9 (12.23%), 70.9 (29.92%), 68.9 (43.97%).
Acknowledgements
5.9. Preparation of dimethyl[1-(9-anthryl)methyleneimino-
2-naphthonato]gallium (8)
We gratefully acknowledge the National Natural Sci-
ence Foundation of China (Project 20072015), Science
Foundation of Jiangsu Province and the 863 High Technol-
ogy Program for their financial support. The research
funds for Y. Pan from Qing-Lan Program of Jiangsu Prov-
ince and Kua-Shi-Ji Program of Education Ministry of
China are also acknowledged.
Prepared and purified in the same manner as described for
1 from 1-(9-anthryl)-methylenenimino-2-naphthol (3.64 g,
10 mmol) and trimethylgallium (1.15 g, 10 mmol). The com-
pound was isolated as orange crystal. Yield: 3.62 g (78.7%
based on TMGa).
M.p.: >200 ꢁC (dec.). Anal. Calc. for C27H22NOGa: C,
72.68; H, 4.97; N, 3.14. Found: C, 72.48; H, 4.67; N,
3.44%. IR data (cmꢀ1): 3050 (w), 2997 (w), 2904 (w),
1617 (m), 1591 (s), 1508 (m), 1462 (s), 1431 (m), 1372
(w), 1351 (m), 1283 (s), 1255 (s), 1209 (w), 1169 (m), 1155
(w), 1144 (w), 996 (m), 886 (m), 818 (m), 750 (s), 732
(vs), 701 (w), 646 (m). 1H NMR data (ppm): 10.23 (s,
1H, –CH@N), 7.26–8.69 (m, 16H, Ar–H), 0.86 (s, 6H,
Ga(CH3)2). MS data: 447.0 (M+, 11.51%), 446.0 (5.16%),
445.1 (15.98%), 433.3 (20.20%), 432.3 (68.42%), 431.3
(30.76%), 430.3 (100.00%), 417.3 (8.06%), 416.2 (22.23%),
415.3 (11.14%), 414.3 (27.37%), 399.8 (18.43%), 347.0
(10.69%), 346.0 (36.09%), 262.9 (5.81%), 261.0 (9.00%),
203.0 (7.64%), 178.0 (7.76%), 177.0 (4.92%), 115.0
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