950 Organometallics, Vol. 21, No. 5, 2002
Beachley et al.
P r ep a r a tion of Ga MesCl(a ca c) by a Liga n d Red istr i-
bu tion Rea ction . A colorless benzene solution (15 mL) of 0.24
g of GaMes2(acac) (0.58 mmol) and 0.14 g of GaCl2(acac) (0.58
mmol) was stirred for 20 h at room temperature. The benzene
was removed by vacuum distillation at room temperature, and
0.33 g of a colorless solid (mp 101.4-106.7 °C) was isolated.
This solid was then recrystallized from pentane at -30 °C to
yield 0.21 g of pure GaMesCl(acac) (0.65 mmol, 56% yield) (mp
108.2-110.5 °C). The small scale of this reaction with the
corresponding mechanical loss of product probably accounts
for the low yield when compared to the metathetical reaction.
P r ep a r a tion of Ga Me[N(SiMe3)2](a ca c) by Meta th esis.
A typical preparation utilized 0.604 g of GaMeCl(acac) (2.76
mmol), 0.461 g of LiN(SiMe3)2 (2.76 mmol), and Et2O. The
reagents were combined and stirred for 2 h at -78 °C, during
which time the color of the reaction mixture changed from
colorless to light yellow. The cloudy, pale yellow reaction
mixture was then warmed to room temperature and was
stirred for an additional 15 h. After the yellow Et2O-soluble
fraction had been separated from the yellowish insoluble solid
by filtration, the volatile components were removed from the
solution by vacuum distillation at room temperature. Purifica-
tion of the product by using a short-path distillation apparatus
under dynamic vacuum and a bath temperature of 50 °C and
a head temperature of 45-47 °C provided 0.812 g of pure
GaMe[N(SiMe3)2](acac) (2.36 mmol, 85.7% yield based on
GaMeCl(acac)).
Ga Me[N(SiMe3)2](a ca c): light yellow liquid at room tem-
perature; soluble in pentane, benzene, and diethyl ether.
Cryoscopic molecular weight, benzene solution, formula weight
344.25 (observed molality, observed mol wt, association):
0.0886, 341, 0.99; 0.0660, 337, 0.98; 0.0405, 335, 0.97. Anal.
Calcd for C12H28GaNO2Si2: C, 41.87; H, 8.20; N, 4.07. Found:
C, 41.96; H, 8.18; N, 4.13. 1H NMR (C6D6, δ): 4.91 (0.5 H, acac
H), 1.54 (6 H, acac CH3), 0.35 (18 H, Si-CH3), 0.13 (3 H, Ga-
CH3). 13C NMR (C6D6, δ): 193.61 (CdO), 101.44 (dCH), 27.44
(acac-CH3), 5.48 (Si-CH3), -4.65 (br, Ga-CH3). IR (neat, Cd
O/CdC region, cm-1): 1587 (vs), 1525 (vs), 1430 (s), 1370 (vs),
1282 (s), 1258 (vs), 1245 (vs), 1207 (m), 1192 (w).
P r ep a r a tion of Ga Cl[N(SiMe3)2](a ca c) by Meta th esis.
In one experiment, 0.468 g of Li[N(SiMe3)2]‚Et2O (1.94 mmol)
was added at room temperature over a period of 20 min to a
colorless benzene solution of 0.465 g of GaCl2(acac) (1.94
mmol). The reaction mixture became yellow within a few
minutes of mixing the reagents. After the reaction mixture
had been stirred at room temperature for 12 h, the solvent
was removed by vacuum distillation to leave a viscous yellow
liquid. Then, 10-15 mL of pentane was added to the yellow
liquid and, upon warming, a light yellow solution above a solid
was observed. The mixture was filtered. The resulting solution
was cooled to -30 °C for 12 h, and a yellow powder formed. A
total of three extractions and crystallizations produced 0.363
g of pure GaCl[N(SiMe3)2](acac) (0.995 mmol, 51.4% based on
GaCl2(acac)).
Ga Cl[N(SiMe3)2](a ca c): yellow solid; soluble in benzene
and slightly soluble in pentane; mp 72.3-74.6 °C dec. Cryo-
scopic molecular weight, benzene solution, formula weight
364.67 (observed molality, observed mol wt, association):
0.0756, 370, 1.01; 0.0545, 368, 1.00; 0.0393, 367, 1.00. Anal.
Calcd for C11H25ClGaNO2Si2: C, 36.23; H, 6.91; N, 3.84;
Found: C, 36.19; H, 6.88; N, 3.71. 1H NMR (C6D6, δ): 4.79
(0.5 H, acac H), 1.39 (6 H, acac CH3), 0.41 (18 H, SiCH3). 13C
NMR (C6D6, δ): 195.63 (CdO), 102.64 (dCH), 27.21 (acac CH3),
5.15 (SiCH3). IR (Nujol mull, CdO/CdC region, cm-1): 1565
(vs), 1545 (sh, vs), 1528 (vs), 1450 (s), 1395 (sh, m), 1355 (vs),
1303 (sh, m), 1289 (s), 1260 (sh, s), 1247 (vs). Crystallographic
quality crystals were grown by vacuum sublimation at 55 °C.
Collection of X-r a y Diffr a ction Da ta a n d Str u ctu r a l
Solu tion for Ga Cl[N(SiMe3)2](a ca c). A well-defined crystal
of approximate orthogonal dimensions 0.2 × 0.2 × 0.4 mm was
sealed into a thin-walled glass capillary as described above.
The crystal was mounted with its extended direction close to
collinear with the Φ axis of a Siemens R3m/V automated four-
circle diffractometer. The Laue symmetry (D2h or mmm)
indicated the orthorhombic crystal system. The systematic
absences (0kl for k ) 2n + 1, h0l for l ) 2n + 1, hk0 for h )
2n + 1) uniquely define the common centrosymmetric ortho-
rhombic space group Pbca (No. 61).18c Two equivalent forms
of data (hkl and hkhl) were collected. The 5396 data were
merged to a unique set of 2490 data (with Rint ) 2.34%), of
which 1568 data with |Fo| > 4.0σ(|Fo|) were considered
“observed”. Details are provided in Table 3.
P r ep a r a tion of Ga MeCl(h fa c) by Meta th esis. A Solv-
Seal flask equipped with a magnetic stirbar and a side-arm
dumper that contained 0.726 g of Na(hfac) (3.15 mmol) was
charged with 0.509 g of GaMeCl2 (3.27 mmol). The flask was
connected to a second Schlenk flask by a medium-porosity
glass frit. After 20 mL of pentane was added to the GaMeCl2
by vacuum distillation, Na(hfac) was added to the colorless
pentane solution at room temperature over a period of 10 min.
The reaction mixture was stirred for 12 h, and then the
pentane-soluble and -insoluble components were separated by
filtration. The pentane-insoluble solid (NaCl) was washed once
with pentane, and then the components volatile at 0 °C were
removed by vacuum distillation from the soluble fraction. The
pentane-soluble product was purified by vacuum distillation
at room temperature, and 0.679 g of GaMeCl(hfac) (2.07 mmol,
65.8% based on GaMeCl2) as a colorless liquid was collected
in a preweighed tube. The compound slowly turned orange
when stored under vacuum at room temperature for 2 days.
The following characterization data were obtained for the
original colorless liquid.
Ga MeCl(h fa c): colorless liquid with a freezing point below
-20 °C; soluble in pentane and benzene. Vapor pressure at
20 °C: 2.3 mmHg. Cryoscopic molecular weight, benzene
solution, formula weight 327.26 (observed molality, observed
mol wt, association): 0.0610, 336.0, 1.03; 0.0483, 334.0, 1.02;
0.0361, 332.2, 1.02. Anal. Calcd for C6H4ClF6GaO2: C, 22.02;
1
H, 1.23. Found: C, 22.16; H, 1.25. H NMR (C6D6, δ): 5.86 (s,
0.7 H, hfac H), - 0.15 (Ga-CH3, 3 H). 13C NMR (C6D6, δ):
182.40 (q, J CO-F ) 37.8 Hz, -CdO), 117.39 (q, J C-F ) 285 Hz,
-CF3), 93.78 (s, dC-), -7.60 (s, br, Ga-CH3). IR (neat, cm-1):
1738 (w), 1700 (w), 1648 (vs), 1623 (vs), 1570 (vs), 1547 (s),
1512 (m), 1509 (m), 1491 (w), 1468 (m), 1441 (sh, vs), 1438
(sh, vs), 1430 (vs), 1360 (m), 1344 (sh, w), 1255 (br, vs). IR
(gas cell, 2.0 mmHg, cm-1): 1650 (vs), 1638 (vs), 1591 (w), 1573
(m), 1550 (m), 1515 (w), 1434 (vs), 1363 (w), 1260 (vs).
P r ep a r a tion of Ga MeCl(h fa c) by a Meth a n e Elim in a -
tion Rea ction . A flask equipped with a magnetic stir bar and
charged with 1.20 g of GaMe2Cl (8.89 mmol) was connected to
a Schlenk flask by a glass elbow. After pentane (∼25 mL) and
1.85 g of H(hfac) (8.89 mmol) were added by vacuum distilla-
tion, the reaction mixture was stirred for 12 h at room
temperature. The components of the product mixture that were
volatile at 0 °C were removed by vacuum distillation. Pure
GaMeCl(hfac) as a colorless liquid (2.73 g, 8.34 mmol, 94.0%
yield) was collected by vacuum distillation at room tempera-
ture into a preweighed tube. The characterization data of this
colorless liquid were identical with that prepared by the
metathetical reaction.
P r ep a r a tion of Ga MesCl(h fa c) by Meta th esis. This
compound was prepared in a manner similar to that described
for GaMeCl(hfac), with the following modifications. The re-
agents GaMesCl2 (0.550 g, 2.12 mmol) and Na(hfac) (0.491 g,
2.13 mmol) were combined in 30 mL of Et2O at room temper-
ature and stirred for 15 h. The Et2O was removed, and 30 mL
of pentane was added by vacuum distillation. Then, the
pentane-soluble components were separated from the insoluble
NaCl and excess Na(hfac) by filtration. Removal of pentane
by vacuum distillation left 0.803 g of GaMesCl(hfac) (1.86
mmol, 87.9% based on GaMesCl2) as a pentane-soluble, light
yellow crystalline solid. The compound slowly turned brownish