308 Inorganic Chemistry, Vol. 40, No. 2, 2001
Luo et al.
1,3-propanediamine (Aldrich), H2NCH2CMe2CH2NMe2, was distilled
over KOH under nitrogen. Chlorotrimethylsilane (Aldrich) was used
as received. The hexanes solution of n-butyllithium (Aldrich) was
titrated using (1R,2S,5R)-(-)-menthol. Diethyl ether, pentane, hexanes,
and toluene were predried over calcium hydride and freshly distilled
from sodium/benzophenone under nitrogen. Benzene-d6 and toluene-
d8 were distilled over calcium hydride under nitrogen. All experiments
were conducted under an oxygen-free, dry-nitrogen atmosphere using
Schlenk and glovebox techniques.
(1.077 g, 3.91 mmol) in 80 mL of Et2O over a period of 20 min. The
mixture was stirred for 2 h and filtered. Volatiles (Et2O and quinucli-
dine) were removed under vacuum from the colorless filtrate, and a
white crystalline compound remained. Et2O (180 mL) was again added,
and the solution was filtered. Upon concentration and storage at -15
°C overnight, small colorless blocks were collected (1.28 g, 69% yield).
Mp: 105-108 °C. 1H NMR (25 °C): δ 0.60 (12H, br s, CMe2), 1.95
(16H, br s, NMe2 and CH2NMe2), 2.94 (6H, br s, NH and CH2NH),
and 5.17 (2H, br s, GaH). 1H NMR (60 °C): δ 0.68 (12H, br s, CMe2),
2.02 (16H, br s, NMe2 and CH2NMe2), 2.93 (6H, br s, NH and CH2-
The quinuclidine adducts of mono- and dichlorogallane, H2GaCl-
(quin) and HGaCl2(quin), were synthesized as previously reported.18
Li[N(H)CH2CMe2CH2NMe2] was prepared from the reaction of
H2NCH2CMe2CH2NMe2 with 1 equiv of n-butyllithium and crystallized
as a colorless compound from pentane solution (90% yield). HN(TMS)-
CH2CMe2CH2NMe2 was obtained as a colorless liquid from the reaction
of chlorotrimethylsilane with Li[N(H)CH2CMe2CH2NMe2] in a 1:1
molar ratio and distilled under a reduced pressure (50 °C/0.01 Torr,
71% yield). Li[N(TMS)CH2CMe2CH2NMe2], prepared from the lithia-
tion of HN(TMS)CH2CMe2CH2NMe2 with n-butyllithium in pentane,
was initially a colorless liquid and solidified to afford a colorless
crystalline solid upon storage. The above as-prepared lithium amides
and HN(TMS)CH2CMe2CH2NMe2 were characterized by 1H NMR and
IR spectroscopy.
1
NH), and 5.32 (2H, br s, GaH). H NMR (21 °C, toluene-d8): δ 0.64
(12H, br s, CMe2), 1.97 (16H, br s, NMe2 and CH2NMe2), 2.87 (6H,
1
br s, NH and CH2NH), and 5.14 (2H, br s, GaH). H NMR (-60 °C,
toluene-d8): δ 0.45 (6H, s) and 0.52 (6H, s) for CMe2, 1.58 (6H, s)
and 1.99 (6H, s) for NMe2, 2.03 (4H, s, CH2NMe2), 2.66 (4H, d, 3JHH
) 13.2 Hz, CH2NH), 3.38 (2H, t, 3JHH ) 13.6 Hz, NH), and 4.93 (2H,
s, GaH). The residual proton (δ 6.98) in toluene-d8 was used as the
internal standard. IR: νGaH, 1870 cm-1; νNH, 3310 cm-1. Anal. Calcd
for C18H34N2Ga2Cl2: C, 35.86; H, 7.31; N, 11.95. Found: C, 35.24;
H, 7.74; N, 11.58.
Synthesis of {[(TMS)2N](H)Ga[N(H)CH2CMe2CH2NMe2]}2, 4. To
a stirred solution of compound 3 (0.400 g, 0.849 mmol) in 40 mL of
toluene at room temperature was added a solution of Li[N(TMS)2]
(0.284 g, 1.70 mmol) in 20 mL of toluene over a period of 5 min. The
mixture was stirred for 3 h and filtered. After the colorless filtrate was
concentrated and stored at -15 °C, colorless plates were collected (0.41
1
Except those indicated otherwise, H NMR spectra were obtained
in benzene-d6 solutions at room temperature on either a Varian INOVA
300 or a Varian UNITY 300 spectrometer. The residual proton (δ 7.15)
in benzene-d6 was used as the internal standard. The IR spectra of KBr
pellets or liquid films between NaCl windows were recorded on a
Nicolet MAGNA-IR 560 spectrometer. Melting points were measured
in sealed glass capillaries and were not corrected. All elemental analyses
were performed by Schwarzkopf Microanalytical Laboratory, Woodside,
NY.
1
g, 67% yield). Mp: 172-175 °C. H NMR: δ 0.42 (36H, s, SiMe3),
0.66 (6H, s) and 1.08 (6H, s) for CMe2, 1.90 (2H, d, J ) 1.8 Hz) and
1.94 (2H, d, J ) 1.8 Hz) for CH2NMe2, 2.12 (12H, s, NMe2), 2.84
(2H, t, J ) 11.1 Hz, NH), 3.18 (4H, d, J ) 12.6 Hz, CH2NH), and
5.31 (2H, br s, GaH). IR: νGaH, 1903 cm-1; νNH, 3201 cm-1. Anal.
Calcd for C26H72N6Si4Ga2: C, 43.33; H, 10.07; N, 11.66. Found: C,
43.73; H, 10.42; N, 11.78.
Synthesis of {H2Ga[N(H)CH2CMe2CH2NMe2]}2, 1. To a stirred
solution of H2GaCl(quin) (1.500 g, 6.87 mmol) in 40 mL of Et2O at
room temperature was added a solution of Li[N(H)CH2CMe2CH2NMe2]
(0.935 g, 6.87 mmol) in 40 mL of Et2O over a period of 10 min. The
mixture was stirred for 2 h and filtered. After volatiles were removed
under vacuum from the filtrate, a colorless, sticky oil remained. To
facilitate crystallization of the oil, pentane (10 mL) was added and
removed immediately under vacuum. Upon storage for a day at room
temperature, the pentane-treated oil solidified to afford a colorless
Synthesis of HGa[N(TMS)(CH2CMe2CH2NMe2)]2, 5. To a stirred
solution of HGaCl2(quin) (0.837 g, 3.31 mmol) in 30 mL of Et2O at
room temperature was added a solution of Li[N(TMS)(CH2CMe2CH2-
NMe2)] (1.380 g, 6.62 mmol) in 20 mL of Et2O over a period of 10
min. The mixture was stirred for 3 h and filtered. After volatiles were
removed from the colorless filtrate under vacuum, a colorless liquid
1
was collected (1.29 g, 82% yield). H NMR: δ 0.38 (18H, s, SiMe3),
0.85 (6H, s), and 1.06 (6H, s) for CMe2, 1.94 (2H, d, 2JHH ) 13.0 Hz)
crystalline solid (1.37 g, 99% yield). Mp: 51-53 °C. H NMR: δ
and 2.23 (2H, d, 2JHH ) 13.5 Hz) for (TMS)NCH2, 2.13 (12H, s, NMe2),
1
2
2
0.73 (12H, s, CMe2), 1.87 (4H, s, Me2NCH2), 2.00 (12H, s, NMe2),
2.89 (2H, d, JHH ) 13.5 Hz), and 3.14 (2H, d, JHH ) 14.0 Hz) for
Me2NCH2 and 4.94 (1H, br s, GaH). IR: νGaH, 1884 cm-1. Anal. Calcd
for C20H51GaN4Si2: C, 50.73; H, 10.86; N, 11.83. Found: C, 50.51;
H, 11.11; N, 11.37. To test for thermal stability, a small amount of the
oil was sealed in a capillary under N2 and slowly heated to 85 °C at
which point the decomposition occurred as indicated by the formation
of gray particles.
3
2.92 (4H, d, JHH ) 6.3 Hz, HNCH2), 3.31 (2H, br s, NH), and 5.26
(4H, br s, GaH2). IR: νGaH, 1875 cm-1; νNH, 3179 cm-1. MS (CI, %,
where fw equals the formula weight of one monomeric unit): 471.2
([3fw - N(H)CH2CMe2CH2NMe2]+, 14), 401.2 ([2fw + H]+, 14), 215.1
([fw + Me]+, 19), 201.1 ([fw + H]+, 100), 131.2 ([Me2NCH2CMe2-
CH2NH3]+, 56). Anal. Calcd for C14H38Ga2N4: C, 41.84; H, 9.53; N,
13.94. Found: C, 38.74; H, 8.97; N, 11.75.
X-ray Data Collection, Structure Solution, and Refinement.
Suitable crystals of 1, 3, 4 were selected and mounted on glass fibers
under a nitrogen atmosphere. The data collections were conducted on
a Siemens SMART system. In each experiment, an initial set of cell
constants was calculated from reflections harvested from three sets of
20 frames. These sets of frames were oriented such that orthogonal
wedges of reciprocal space were surveyed. The data collection technique
was generally known as a hemisphere collection. A randomly oriented
region of reciprocal space was surveyed to the extent of 1.3 hemispheres
to a resolution of 0.84 Å. Three major swaths of frames were collected
with 0.30° steps in ω.
The space groups were determined on the basis of systematic
absences and intensity statistics. A successful direct-methods solution
was applied to the structures of compounds 3 and 4, which provided
most non-hydrogen atoms from the E-maps. Several full-matrix, least
squares/difference Fourier cycles were performed that located the
remainder of the non-hydrogen atoms. All non-hydrogen atoms were
refined with anisotropic displacement parameters. All hydrogen atoms,
except those indicated below, were placed in ideal positions and refined
as riding atoms with relative isotropic displacement parameters. The
hydrides and the hydrogen atoms of the amido groups were refined
isotropically. The structure of compound 1 was solved by Patterson
Synthesis of H2Ga[N(TMS)CH2CMe2CH2NMe2], 2. To a precooled
(-78 °C) solution of H2GaCl(quin) (0.800 g, 3.66 mmol) in 40 mL of
Et2O was added a solution of Li[N(TMS)CH2CMe2CH2NMe2] (0.763
g, 3.66 mmol) in 20 mL of Et2O over a period of 10 min. The mixture
was stirred for 0.5 h at -78 °C and then for 3 h at room temperature.
Upon filtration and removal of volatiles in the filtrate under vacuum,
1
a slightly yellow liquid was collected (0.86 g, 86% yield). H NMR:
δ 0.33 (9 H, s, SiMe3), 0.71 (6H, s, CMe2), 1.87 (6H, s, NMe2), 1.89
(2H, s, (TMS)NCH2), 3.04 (2H, s, Me2NCH2), and 4.97 (2H, br s,
GaH2). IR: νGaH, 1825 and 1869 cm-1. MS (CI, %, where fw equals
the formula weight): 545.5 ([2fw + H]+, 2.5), 343.2 ([fw + GaH2]+,
4), 273.2 ([fw + H]+, 100), 257.2 ([fw - Me]+, 16), 203.3 ([HN-
(TMS)CH2CMe2CH2NMe2 + H]+, 72), 187.2 ([HN(TMS)CH2CMe2-
CH2NMe2 - Me]+, 34). Anal. Calcd for C10H27GaN2Si: C, 43.97; H,
9.96; N, 10.26. Found: C, 46.18; H, 10.17; N, 10.28. To test for thermal
stability, a small amount of the oil was sealed in a capillary under N2
and slowly heated to 135 °C at which point the decomposition occurred
as indicated by the formation of gray particles.
Synthesis of {H(Cl)Ga[N(H)CH2CMe2CH2NMe2]}2, 3. To a stirred
solution of HGaCl2(quin) (2.000 g, 7.91 mmol) in 50 mL of Et2O at
room temperature was added a solution of Li[N(H)CH2CMe2CH2NMe2]