Syntheses and structures of quinuclidine-stabilized amido- and azidogallanes

Article abstract of DOI:10.1021/ic9910110

Quinuclidine-stabilized amido- and azidogallanes, HGa[N(TMS)₂]₂(quin) (1), H₂Ga[N(TMS)₂](quin) (2), HGa[N(H)(2,6-(i)Pr₂C₆H₃)]₂(quin) (3), and H₂GaN₃(quin) (4), were synthesized from the quinuclidine adducts of mono- and dichlorogallane. Structural determinations revealed that all compounds were monomeric with four-coordinate gallium centers. Reactions of the five-coordinate compound, HGaCl₂(quin)₂, with 2 equiv of Li[N(TMS)₂] or Li[N(H)(2,6-(i)Pr₂C₆H₃)] resulted in the isolation of compound 1 or 3. A ligand redistribution during the reaction of H₂GaCl(quin) with Li[N(H)(2,6-(i)Pr₂C₆H₃)] produced compound 3 and H₃Ga(quin) in a 1:1 molar ratio.

Full text of DOI:10.1021/ic9910110

Inorg. Chem. 2000, 39, 1705-1709
1705
Syntheses and Structures of Quinuclidine-Stabilized Amido- and Azidogallanes
Bing Luo, Victor G. Young, Jr., and Wayne L. Gladfelter*
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
ReceiVed August 23, 1999
Quinuclidine-stabilized amido- and azidogallanes, HGa[N(TMS)2]2(quin) (1), H2Ga[N(TMS)2](quin) (2), HGa-
[N(H)(2,6-iPr2C6H3)]2(quin) (3), and H2GaN3(quin) (4), were synthesized from the quinuclidine adducts of mono-
and dichlorogallane. Structural determinations revealed that all compounds were monomeric with four-coordinate
gallium centers. Reactions of the five-coordinate compound, HGaCl2(quin)2, with 2 equiv of Li[N(TMS)2] or
Li[N(H)(2,6-iPr2C6H3)] resulted in the isolation of compound 1 or 3. A ligand redistribution during the reaction
of H2GaCl(quin) with Li[N(H)(2,6-iPr2C6H3)] produced compound 3 and H3Ga(quin) in a 1:1 molar ratio.
Introduction
of one or two of the hydrides.15-19 Recently, we reported the
syntheses of thermally robust quinuclidine-stabilized, mono- and
Much recent interest in gallium chemistry focuses on the
syntheses of novel compounds that are precursors to solid-state
materials such as gallium nitride.1-8 Gallane and its derivatives
are of particular interest because the absence of direct Ga-C
bonds minimizes the potential carbon contamination. The high
thermal reactivity of many of the hydrides allows depositions
to be conducted at lower temperatures. For example, GaN films
were prepared at a temperature as low as 200 °C using (H2-
GaN3)n as the precursor in chemical vapor deposition pro-
cesses,8,9 and GaN nanocrystals were synthesized from [H2-
GaNH2]3 either by direct pyrolysis or dehydrogenation in a
liquid-ammonia medium.1,6 As problems associated with either
the stability of the precursors or the quality of the GaN products
still exist, syntheses of new gallane compounds are needed.
All structurally characterized amidogallane compounds in-
dichlorogallane,20 which offer an alternative route to novel
gallane derivatives. In this paper, we report the syntheses and
structures of a monomeric monoamidogallane, H2GaN(TMS)2-
(quin), and monomeric diamidogallanes, HGa[N(TMS)2]2(quin)
and H[GaN(H)(2,6-iPr2C6H3]2(quin), where TMS is trimethyl-
silyl and quin is quinuclidine. In addition, we report the synthesis
and structure of a quinuclidine-stabilized azidogallane, H2-
GaN3(quin). The compound (H2GaN3)n was proposed to be
trimeric in the gas-phase based on vibrational data and ab initio
calculations.8
Experimental Section
Materials and General Procedures. The quinuclidine adducts of
mono- and dichlorogallane were synthesized as previously reported.20
Lithium bis(trimethylsilyl)amide (Aldrich) was recrystallized from
hexanes. Sodium azide (Aldrich) was dried under vacuum (∼0.01 Torr)
at room temperature for 24 h. The hexanes solution of n-butyllithium
(Aldrich) was titrated using (1R,2S,5R)-(-)-menthol. 2, 6-Diisopropyl-
aniline (Fluka) was distilled over calcium hydride (75 °C/0.01 Torr).
Lithium 2,6-diisopropylanilide was prepared as an off-white powder
from the reaction of the corresponding amine and n-butyllithium in a
1:1 molar ratio and was characterized by 1H NMR and IR spectra.
Diethyl ether, pentane, hexanes, and benzene were predried over
calcium hydride and freshly distilled over sodium/benzophenone under
nitrogen. Benzene-d6 was distilled over calcium hydride under nitrogen.
All experiments were conducted under an oxygen-free, dry-nitrogen
atmosphere using Schlenk and glovebox techniques.
12
cluding [H2GaN(CH2)2]3,10 [H2GaNMe2]2,11 and [H2GaNH2]3
exist as di- or trimeric species. Even in the presence of Lewis
bases, monomeric amidogallane derivatives are unknown,
although monomeric Lewis base adducts of other gallium
compounds are common.13,14 Most of the reported gallane
derivatives were synthesized from H3Ga(NMe3) by elimination
(1) Hwang, J.-W.; Campbell, J. P.; Kozubowski, J.; Hanson, S. A.; Evans,
J. F.; Gladfelter, W. L. Chem. Mater. 1995, 7, 517.
(2) Neumayer, D. A.; Cowley, A. H.; Decken, A.; Jones, R. A.; Lakhotia,
V.; Ekerdt, J. G. J. Am. Chem. Soc. 1995, 117, 5893-5894.
(3) Janik, J. F.; Wells, R. L. Chem. Mater. 1996, 8, 2708-2711.
(4) Kouvetakis, J.; McMurran, J.; Matsunaga, P.; O’Keeffe, M.; Hubbard,
J. L. Inorg. Chem. 1997, 36, 1792-1797.
(5) Frank, A. C.; Stowasser, F.; Sussek, H.; Pritzkow, H.; Miskys, C. R.;
Ambacher, O.; Giersig, M.; Fisher, R. A. J. Am. Chem. Soc. 1998,
120, 3512-3513.
(6) Jegier, J. A.; Mckernan, S.; Gladfelter, W. L. Chem. Mater. 1998, 10,
2041.
1H NMR spectra were obtained in benzene-d6 solutions at room
temperature on a Varian INOVA 300 spectrometer, and the residual
proton (δ 7.15) in C6D6 was used as the internal standard. In the cases
where the compounds contained aromatic hydrogens, the sharp singlet
(δ 0.288) from silicone grease was used as the internal standard. The
(7) McMurran, J.; Kouvetakis, J.; Nesting, D. C.; Smith, D. J.; Hubbard,
J. L. J. Am. Chem. Soc. 1998, 120, 5233-5237.
(8) McMurran, J.; Dai, D.; Balasubramanian, K.; Steffek, C.; Kouvetakis,
J.; Hubbard, J. L. Inorg. Chem. 1998, 37, 6638-6644.
(9) McMurran, J.; Kouvetakis, J.; Smith, D. J. Appl. Phys. Lett. 1999,
74, 883-885.
(14) Tuck, D. G. In ComprehensiVe Organometallic Chemistry; Wilkinson,
G., Ed.; Pergamon Press Ltd.: Oxford, U.K., 1982; pp 683-723.
(15) Storr, A. J. Chem. Soc. A 1968, 2065-2068.
(16) Storr, A.; Penland, A. D. J. Chem. Soc. A 1971, 1237-1242.
(17) Storr, A.; Thomas, B.; Penland, A. J. Chem. Soc., Dalton Trans. 1972,
326-330.
(10) Harrson, W.; Storr, A.; Trotter, J. J. Chem. Soc., Dalton Trans. 1972,
1554-1555.
(11) Baxter, P. L.; Downs, A. J.; Rankin, D. W. H.; Robertson, H. E. J.
Chem. Soc., Dalton Trans. 1985, 807-814.
(12) Campell, J. P.; Hwang, J.-W.; Young, V. G., Jr.; Von Dreele, R. B.;
Cramer, C. J.; Gladfelter, W. L. J. Am. Chem. Soc. 1998, 120, 521-
531.
(18) Atwood, J. L.; Bott, S. G.; Jones, C.; Raston, C. L. Inorg. Chem. 1991,
30, 4868-4870.
(19) Janik, J. F.; Wells, R. L.; Young, V. G., Jr.; Rheingold, A. L.; Guzei,
I. A. J. Am. Chem. Soc. 1998, 120, 532-537.
(20) Luo, B.; Young, V. G., Jr.; Gladfelter, W. L. J. Chem. Soc., Chem.
Commun. 1999, 123-124.
(13) Greenwood, N. N. AdV. Inorg. Chem. Radiochem. 1963, 5, 91-134.
10.1021/ic9910110 CCC: $19.00 © 2000 American Chemical Society
Published on Web 03/30/2000

1706 Inorganic Chemistry, Vol. 39, No. 8, 2000
Luo et al.
IR spectra of KBr pellets 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.
min. The mixture was stirred for 2 h and filtered. After ether was
removed under vacuum from the yellow filtrate, a slightly yellow, sticky
oil remained. Pentane (8 mL) was added to dissolve it, and the solution
was stored at -15 °C for crystallization. The colorless crystalline
product was identified as a mixture of HGa[N(H)(2,6-iPr2C6H3)]2(quin)
(3) and H3Ga(quin) (0.61 g, 74.1% yield for total). The 1H NMR
spectrum of the mixture indicated that the molar ratio of the two
compounds was close to 1:1.
X-ray Data Collection, Structure Solution, and Refinement.
Suitable crystals of compounds 1-4 were selected and mounted on
top of glass fibers under a nitrogen atmosphere. All 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 or 25 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. In the event the
lattice was triclinic some additional sets of frames were collected to
better model the absorption correction. The final cell constants were
calculated from a set of strong reflections which were 8192 for 1, 6232
for 2, 7252 for 3, and 4660 for 4.
The space groups were determined on the basis of systematic
absences and intensity statistics. A successful direct-methods solution
was applied to all the structures which provided most non-hydrogen
atoms from the E-maps. Several full-matrix, least-squares/difference
Fourier cycles were performed which located the remainder of the non-
hydrogen atoms. All non-hydrogen atoms were refined with anisotropic
displacement parameters. All hydrogen atoms, except those listed below,
were placed in ideal positions and refined as riding atoms with relative
isotropic displacement parameters. The hydrides in all compounds and
the hydrogens of the amido groups in compound 3 were refined
isotropically. The hydrides, H1G and H2G, in compound 4 were refined
with a fixed distance to the metal. The experimental conditions and
unit cell information are summarized in Table 1.
Synthesis of HGa[N(TMS)2]2(quin) (1). To a stirred solution of
HGaCl2(quin) (0.600 g, 2.37 mmol) in 30 mL of Et2O at room
temperature was added a solution of Li[N(TMS)2] (0.794 g, 4.75 mmol)
in 10 mL of Et2O over a period of 10 min. The mixture was stirred for
4 h and filtered. Ether was removed under vacuum from the colorless
filtrate. Hexanes (10 mL) were then added, and the solution was filtered.
Upon storage at -15 °C overnight, colorless plates were collected (0.64
1
g, 54% yield). Mp: 90-93 °C. H NMR: δ 0.29 (36H, s, SiCH3),
1.22 (6H, m, CH2), 1.43 (1H, m, CH), 2.76 (6H, t, NCH2), 6.35 (1H,
br s, GaH). IR: νGaH, 1893 cm-1. Anal. Calcd for C19H50GaN3Si4: C,
45.40; H, 10.03; N, 8.36. Found: C, 44.71; H, 9.92; N, 8.22.
Synthesis of H2Ga[N(TMS)2](quin) (2). To a stirred solution of
H2GaCl(quin) (1.00 g, 4.58 mmol) in 60 mL of Et2O at room
temperature was added a solution of Li[N(TMS)2] (0.766 g, 4.58 mmol)
in 20 mL of Et2O over a period of 10 min. The mixture was stirred for
17 h and filtered. The colorless filtrate was concentrated and cooled in
a 2-propanol/dry ice bath for a short time. After the crystal seeds formed,
the filtrate was stored in a freezer (-15 °C), and colorless plates were
1
eventually collected (1.278 g, 81% yield). Mp: 74-75 °C. H NMR:
δ 0.45 (18H, s, SiCH3), 0.97 (6H, m, CH2), 1.18 (1H, m, CH), 2.61
(6H, m, NCH2), 4.94 (2H, br s, GaH2). IR: νGaH, 1855 and 1872 cm-1
.
Anal. Calcd for C13H33GaN2Si2: C, 45.48; H, 9.69; N, 8.16. Found:
C, 43.40; H, 9.61; N, 7.70.
Synthesis of HGa[N(H)(2,6-iPr2C6H3)]2(quin) (3). To a stirred
solution of HGaCl2(quin) (0.600 g, 2.37 mmol) in 30 mL of Et2O at
room temperature was added a solution of Li[N(H)(2,6-iPr2C6H3)] (0.870
g, 4.75 mmol) in 30 mL of Et2O over a period of 5 min. The mixture
was stirred for 17 h and filtered. The yellow filtrate was concentrated
and stored at -15 °C. Colorless plates were collected (0.828 g, 65%
1
yield). Mp: 129 °C (dec). H NMR: δ 0.89 (6H, m, CH2), 1.13 (1H,
m, CH), 1.36 (24H, d, CH3), 2.60 (6H, t, NCH2), 3.02 (2H, s, NH),
3.56 (4H, m, CHMe2), 5.25 (1H, br s, GaH), 6.96 (2H, m, aromatic),
7.19 (4H, m, aromatic). IR: νGaH, 1909 cm-1; νNH, 3384 and 3375 cm-1
.
Anal. Calcd for C31H50GaN3: C, 69.66; H, 9.43; N, 7.86. Found: C,
69.11; H, 9.73; N, 7.75.
Results and Discussion
Synthesis of H2GaN3(quin) (4). To a stirred slurry of NaN3 (0.600
g, 9.14 mmol) in 35 mL of benzene at room temperature was added a
solution of H2GaCl(quin) (1.000 g, 5.58 mmol) in 30 mL of benzene.
The mixture was heated to 55 °C, stirred for 46 h, and then filtered.
After the benzene was removed from the colorless filtrate, a white waxy
solid remained. Hexanes (100 mL) were added to the waxy solid, and
the solution was filtered. Upon storage at -15 °C overnight, colorless
needles were collected (0.30 g, 29% yield). Mp: 47-50 °C. 1H NMR:
δ 0.76 (6H, s, CH2), 1.00 (1H, m, CH), 2.33 (6H, t, NCH2), 4.81 (2H,
Syntheses of Quinuclidine-Stabilized Amido- and Azido-
gallanes. The syntheses of compounds 1 and 3 from HGaCl2-
(quin) and related reactions from HGaCl2(quin)2 are summarized
in Scheme 1. Scheme 2 outlines the syntheses of compounds 2
and 4 from H2GaCl(quin) and the reaction of H2GaCl(quin) with
Li[N(H)(2,6-iPr2C6H3)]. All compounds were characterized by
1H NMR and IR spectroscopy and single-crystal X-ray diffrac-
tion. Agreement between calculated and measured elemental
analyses was acceptable for 1 and 3, but 2 was low in carbon
and 4 was low in nitrogen. In the latter case, the loss of N2
from the azido ligand during analysis was probably responsible
for the discrepancy.
Compounds 1-3 were isolated in moderate yields. In the
preparation of compound 3 the use of isolated Li[N(H)(2,6-
iPr2C6H3)], rather than its solution prepared in situ, was to better
control the stoichiometry of the starting materials. The IR and
1H NMR spectra of these compounds were in accord with their
formulas. The δGaH of compound 1 (6.35 ppm) appeared most
downfield of all previously reported gallane derivatives. The
νGaH at 1893 cm-1 was consistent with related compounds.20
These compounds were stable for at least several months under
an inert atmosphere at room temperature. In an attempt to
synthesize [H2GaN(TMS)2]n by the elimination of volatile
HSiMe3,19 Wells et al. reported that no reaction occurred
between H3Ga(NMe3) and N(TMS)3. The route used here,
involving LiCl elimination, facilitated the formation of Ga-N
bonds in the syntheses of compounds 1 and 2.
br s, GaH). IR: νGaH, 1915 and 1893 cm-1; νasNNN, 2091 cm-1; νsNNN
,
1293 cm-1. Anal. Calcd for C7H15GaN4: C, 37.38; H, 6.72; N, 24.91.
Found: C, 36.77; H, 6.73; N, 21.32.
Reaction of HGaCl2(quin)2 with 2 Li[N(TMS)2]. To a stirred
solution of HGaCl2(quin)2 (0.800 g, 2.20 mmol) in 50 mL of Et2O at
room temperature was added a solution of LiN(TMS)2 (0.735 g, 4.40
mmol) in 20 mL of Et2O over a period of 5 min. The mixture was
stirred for 6 h and filtered. The colorless filtrate was concentrated and
stored in a freezer (-15 °C). Colorless plates were collected and
identified as HGa[N(TMS)2]2(quin) (1) (0.935 g, 85% yield based on
HGaCl2(quin)2).
Reaction of HGaCl2(quin)2 with 2 Li[N(H)(2,6-iPr2C6H3)]. To a
stirred solution of HGaCl2(quin)2 (0.800 g, 2.20 mmol) in 40 mL of
Et2O at room temperature was added a solution of Li[N(H)(2,6-
iPr2C6H3)] (0.805 g, 4.40 mmol) in 30 mL of Et2O over a period of 10
min. The mixture was stirred for 3 h and filtered. The yellow filtrate
was concentrated and stored at -15 °C for crystallization. The colorless
crystals were identified as HGa[N(H)(2, 6 -iPr2C6H3)]2(quin) (3) (0.80
g, 68% yield based on HGaCl2(quin)2).
Reaction of H2GaCl(quin) with Li[N(H)(2,6-iPr2C6H3)]. To a
stirred solution of H2GaCl(quin) (0.500 g, 2.29 mmol) in 20 mL of
Et2O at room temperature was added a solution of LiN[(H)(2,6-
iPr2C6H3)] (0.419 g, 2.29 mmol) in 20 mL of Et2O over a period of 10
Compound 4, synthesized in a 29% yield, was stable as
colorless needles at -15 °C for several days and a much shorter

Quinuclidine-Stabilized Amido- and Azidogallanes
Inorganic Chemistry, Vol. 39, No. 8, 2000 1707
Table 1. Crystallographic Data for Compounds 1-4
chem formula
C19H50GaN3Si4 (1)
C13H33GaN2Si2 (2)
C31H50GaN3 (3)
C7H15GaN4 (4)
fw
502.70
P1h
343.31
P21/n
11.33920(1)
14.78540(1)
12.0588(2)
534.46
P21/n
10.7610(1)
19.4052(3)
14.3919(2)
224.95
P21/n
7.1580(2)
22.7772(7)
12.5316(3)
space group
a, Å
b, Å
10.9550(2)
11.3715(1)
11.9400(2)
79.681(1)
85.018(1)
87.772(1)
1457.42(4)
2
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
112.3670(1)
97.650(1)
101.6470(1)
1869.61(4)
4
2978.56(7)
4
2001.07(1)
8
T, °C
λ, Å
-100
0.710 73
F
calcd, g cm-3
1.146
11.18
0.0235, 0.0639
1.220
15.89
0.0258, 0.0574
1.192
9.46
0.0281, 0.0630
1.493
27.06
0.0479, 0.0840
µ, cm-1
R1, wR2a [I > 2σ(I)]
a R1 ) ∑||Fo - Fc||/∑|Fo| and wR2 ) {∑[w(Fo2 - Fc2)2] /∑[w(Fo )2]}1/2, where w ) 1/[σ2(Fo ) + (aP)2 + (bP)], P ) (Fo + 2Fc2)/3 and a, b are
2
2
2
constants given in the Supporting Information.
Scheme 1a
represented a compromise of the two competing factors.
Unfortunately, the low thermal stability prohibited use of this
compound as a precursor to GaN in a MOCVD process which
utilizes standard vapor phase delivery methods. It may be
feasible to use compound 4 in a direct liquid injection system.
The attempt to prepare H2Ga[N(H)(2,6-iPr2C6H3)](quin) via
the reaction of H2GaCl(quin) with LiN[(H)(2,6-iPr2C6H3)] was
unsuccessful. In addition to LiCl, a mixture of compound 3 and
H3Ga(quin) was isolated in a 1:1 molar ratio as determined by
1H NMR spectroscopy. The attempt to further separate them
was not totally successful, and only a small fraction of H3Ga-
(quin) and an unidentified oil were obtained. This result implied
that a ligand redistribution reaction had taken place via a possible
intermediate, H2Ga[N(H)(2,6-iPr2C6H3)](quin) (Scheme 2). Hy-
drido/amido ligand redistributions have been found in the
reactions of [H2GaNH2]3 with Lewis bases including tetra-
hydrofuran, quinuclidine, and tricyclohexylphosphine.6
The reactions of the five coordinate HGaCl2(quin)2 with LiN-
[(TMS)2] or Li[N(H)(2,6-iPr2C6H3)] in a 1:2 molar ratio resulted
in the isolation of the four-coordinate compound 1 or 3. The
steric congestion produced by the bulky organoamido ligands
undoubtedly limited the stoichiometry to one quinuclidine per
gallium.
a Key: (i) 2 Li[N(TMS)2], -2 LiCl; (ii) 2 Li[N(H)(2,6-iPr2C6H3)],
-2 LiCl; (iii) 2 Li[N(TMS)2], -2 LiCl, -quin; (iv) 2 Li[N(H)(2,6-
iPr2C6H3)], -2 LiCl, -quin.
Scheme 2a
Structural Studies. Compounds 1-4 were all monomeric
with the gallium atoms adopting distorted tetrahedral geometries.
The Ga-N bond distances of the quinuclidine ligands ranged
from 2.028(3) to 2.108(2) Å, comparable to those in H3Ga-
(quin) (2.063(4) Å)21 and HGaCl2(quin) (2.017(3) Å)20 and
shorter than those in the five-coordinate compounds, H2GaCl-
(quin)2 (2.259(2) Å) and HGaCl2(quin)2 (2.254(8) and
2.232(8) Å).20 Selected bond lengths and angles for 1 and 2 are
listed in Table 2, and those for 3 and 4, in Table 3.
Compound 1 crystallized in space group P1h with one
molecule in the asymmetric unit, and the molecular structure
of 1 is shown in Figure 1. The largest angle around the Ga was
found between the two amido nitrogens (119.41(6)°), and the
smallest was between the hydride and the nitrogen of the
quinuclidine (93.7(8)°). The geometries at both amido nitrogens,
N2 and N3, were nearly planar with the sum of the angles
around each being 357.82 and 359.14°, respectively. All angles
around N3 were within 120 ( 2°, and the two N-Si bond
lengths were identical (1.7387(14) and 1.7381(14) Å). For N2,
the angle of Ga1-N2-Si2 (135.97(8)°) was about 20° larger
a Key: (i) Li[N(TMS)2], -LiCl; (ii) NaN3, -NaCl; (iii) Li[N(H)(2,6-
iPr2C6H3)], -LiCl.
time at room temperature. It was difficult to optimize the
reaction conditions because the limited solubility of NaN3
requires a long reaction time and a relatively high reaction
temperature. The actual reaction conditions (55 °C, ∼2 d)
(21) Atwood, J. L.; Bott, S. G.; Elms, F. M.; Jones, C.; Raston, C. L. Inorg.
Chem. 1991, 30, 3792-3793.

1708 Inorganic Chemistry, Vol. 39, No. 8, 2000
Luo et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1 and 2
C19H50GaN3Si4 (1)
C13H33GaN2Si2 (2)
Ga1-N1
2.1057(14)
1.9315(13)
1.9138(13)
1.49(2)
1.7521(14)
1.7277(14)
1.7387(14)
1.7381(14)
Ga1-N1
2.108(2)
1.913(2)
1.473(2)
1.462(2)
1.736(2)
1.723(2)
Ga1-N2
Ga1-N3
Ga1-H1
N2-Si1
N2-Si2
N3-Si3
N3-Si4
Ga1-N2
Ga1-H1G
Ga1-H2G
N2-Si1
N2-Si2
N1-Ga1-N2
N1-Ga1-N3
N2-Ga1-N3
N1-Ga1-H1
N2-Ga1-H1
N3-Ga1-H1
Ga1-N2-Si1
Ga1-N2-Si2
Si1-N2-Si2
Ga1-N3-Si3
Ga1-N3-Si4
Si3-N3-Si4
113.04(6)
105.48(5)
119.41(6)
93.7(8)
107.3(7)
115.0(7)
106.19(7)
135.97(8)
116.98(7)
121.53(7)
118.17(7)
118.12(8)
N1-Ga1-N2
H1G-Ga1-H2G
N1-Ga1-H1G
N1-Ga1-H2G
N2-Ga1-H1G
N2-Ga1-H2G
Ga1-N2-Si1
Ga1-N2-Si2
Si1-N2-Si2
106.26(7)
117.6(2)
98.16(10)
102.36(10)
115.87(11)
113.42(11)
114.85(9)
121.32(10)
122.42(10)
Figure 1. Structure of HGa[N(TMS)2]2(quin) (1). The non-hydrogen
atoms are shown at the 50% probability level. The hydrogen atoms
except the hydride are omitted for clarity.
usually short intermolecular distances were found in the crystal
structure of compound 1, suggesting that the distortion of this
N(TMS)2 group be attributed to the repulsion between the
N(TMS)2 group and other ligands. In particular, close contacts
existed between C12 and two carbon atoms in the quinuclidine
ligand, C1 (3.703(3) Å) and C3 (3.584(3) Å), and between C12
and one of the methyls, C15, in the other N(TMS)2 group
(3.740(3) Å). According to Pauling,27 the average van der Waals
radii of methyl and methylene groups are 2.00 Å. The action
of these nonbonded repulsion forces on C12 was also reflected
in the enlarged N2-Si2-C12 angle (118.00(8)°). The other
N-Si-C angles in this compound were in the range from
111.38(9) to 114.67(8)°. The hydrogen atoms on these carbon
atoms were assigned as riding atoms, and the accuracy of the
distances between these hydrogen atoms is questionable. A
comparison to the normal van der Waals H‚‚‚H distance (2.4
Å),27 the shortest distances between the hydrogen atoms on C12
and the hydrogen atoms on other groups were calculated as
2.088 Å for H12A‚‚‚H1C, 2.185 Å for H12C‚‚‚H3A, and 2.034
Å for H12C‚‚‚H15B.
The molecular structure of compound 2, which crystallized
in space group P21/n with one molecule in the asymmetric unit,
is shown in Figure 2. The largest bond angle around Ga was
found between the two hydrides (117.6(2)°), and the smallest
was between one hydride (H1G) and the nitrogen of the
quinuclidine (98.16(10)°). Large H-Ga-H angles have also
been reported in the structures of 4 (see below), five-coordinate
H2GaCl(quin)2 (127(2)°), and H5Ga3[(NMeCH2)2]2 (127°).18 In
H2GaCl(PCy3)28 and [2,6-(Me2NCH2)2C6H3]GaH2,29 however,
the H-Ga-H angles were 103.0(1) and 116(4)°, respectively.
The geometry at the amido nitrogen (N2) was nearly planar
with the sum of the angles at the nitrogen being 358.6°. The
Ga-H bond lengths were 1.473(2) and 1.462(2) Å, and the bond
length of the Ga-N to the amido group was 1.913(2) Å. Two
methyls (C11 and C12) on one of the trimethylsilyl groups were
disordered.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 3 and 4
C31H50GaN3 (3) C7H15GaN4 (4)
Ga1-N1
2.0831(14)
1.902(2)
1.899(2)
1.47(2)
1.407(2)
0.78(2)
Ga1-N1
2.063(3)
1.922(5)
1.43(2)
Ga1-N2
Ga1-N3
Ga1-H1
N2-C8
Ga1-N2
Ga1-H1G
Ga1-H2G
N2-N3
1.41(2)
1.179(6)
1.123(7)
2.028(3)
1.992(5)
1.38(6)
1.33(5)
1.041(6)
1.226(7)
N2-H2N
N3-C20
N3-H3N
N3-N4
1.408(2)
0.79(2)
Ga2-N5
Ga2-N6
Ga2-H3G
Ga2-H4G
N6-N7
N7-N8
N1-Ga1-N2
N1-Ga1-N3
N2-Ga1-N3
N1-Ga1-H1
N2-Ga1-H1
N3-Ga1-H1
Ga1-N2-H2N
Ga1-N2-C8
H2N-N2-C8
Ga1-N3-H3N
Ga1-N3-C20
H3N-N3-C20
102.47(6)
101.48(6)
109.89(7)
103.6(8)
119.1(7)
117.2(7)
105(2)
127.38(12)
110(2)
116(2)
N1-Ga1-N2
H1G-Ga1-H2G
N1-Ga1-H1G
N1-Ga1-H2G
N2-Ga1-H1G
N2-Ga1-H2G
Ga1-N2-N3
N2-N3-N4
N5-Ga2-N6
H3G-Ga2-H4G
N5-Ga2-H3G
N5-Ga2-H4G
N6-Ga2-H3G
N6-Ga2-H4G
Ga2-N6-N7
N6-N7-N8
100.0(2)
132(3)
104(2)
101(2)
103(2)
113(2)
121.6(4)
168.4(6)
98.1(2)
128(3)
106(2)
103(2)
107(2)
111(2)
124.0(4)
176.2(6)
122.61(12)
111(2)
than that of Ga1-N2-Si1 (106.19(7)°), and the corresponding
Si-N bond lengths were 1.7521(14) and 1.7277(14) Å. This
feature was not observed in compound 2 and other group 13
compounds containing one or more bis(trimethylsilyl)amido
groups such as ClGaN(TMS)2,22 Ga[N(TMS)2]3,22 MesAl-
[N(TMS)2]2,22 Al[N(TMS)2]3,23 In[N(TMS)2]3,24 ArGa(Cl)-
[N(TMS)2],25 ArIn[N(TMS)2]2,25 and Tl[N(TMS)2]3.26 No un-
The molecular structure of compound 3, which crystallized
in space group P21/n with one molecule in the asymmetric unit,
(22) Brothers, P. J.; Wehmschulte, J.; Olmstead, M. M.; Ruhlandt-Senge,
K.; Parkin, S. R.; Power, P. P. Organometallics 1994, 13, 2792-
2799.
(23) Sheldrick, G. M.; Sheldrick, W. S. J. Chem. Soc. A 1969, 2279.
(24) Petrie, M. A.; Ruhlandt-Senge, K.; Hope, H.; Power, P. P. Bull. Soc.
Chim. Fr. 1993, 130, 851-855.
(27) Pauling, L. The Nature of The Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; pp 257-264.
(28) Elms, F. M.; Koutsantonis, G. A.; Raston, C. L. J. Chem. Soc., Chem.
Commun. 1995, 1669-1670.
(25) Leung, W.-P.; Chan, C. M. Y.; Wu, B.-M.; Mak, T. C. W.
Organometallics 1996, 15, 5179-5184.
(29) Cowley, A. H.; Gabba¨ı, F. P.; Atwood, D. A.; Carrano, C. J.; Mokry,
L. M.; Bond, M. R. J. Am. Chem. Soc. 1994, 116, 1559-1660 and
Supporting Information.
(26) Allmann, R.; Henke, W.; Krommes, P.; Lorberth, J. J. Organomet.
Chem. 1978, 162, 283.

Quinuclidine-Stabilized Amido- and Azidogallanes
Inorganic Chemistry, Vol. 39, No. 8, 2000 1709
Figure 4. Structures of the two independent molecules of H2GaN3-
(quin) (4). The non-hydrogen atoms are shown at the 50% probability
level. The hydrogen atoms except the hydrides are omitted for clarity.
The atoms labeled N2D-N3D-N4D represent the disordered azide
location.
Figure 2. Structure of H2Ga[N(TMS)2](quin) (2). The non-hydrogen
atoms are shown at the 50% probability level. The disorders on C11
and C12 and the hydrogen atoms except the hydrides are omitted for
clarity.
two orientations as shown in Figure 4. The position denoted by
N2D, N3D, and N4D represented 10% of the electron density
attributable to the azido ligand. The hydrides corresponding to
this orientation were not located. Within experimental error, the
angles of H1G-Ga1-H2G and H3G-Ga2-H4G were equal
(132(3) and 128(3)°). The angles at N2 and N6 were 121.6(4)
and 124.0(4)°, respectively. The geometry of the azido group
(N2-N3-N4) was somewhat bent (168.4(6)°), whereas N6-
N7-N8 was close to linear (176.2(6)°). In the azido group
attached to Ga1 the distance of N2-N3 (1.179(6) Å) was longer
than N3-N4 (1.123(7) Å) while in the azido group attached to
Ga2 the distance of N6-N7 (1.041(6) Å) was shorter than that
of N7-N8 (1.226(7) Å). Only the former case has been observed
in the previously published azidogallium compounds including
Me2GaN3,30 [(Me2N)(N3)Ga(µ-NMe2)]2,2 [HClGaN3]4,7 [2,6-
(Me2NCH2)2C6H3]Ga(N3)2,31 Ga(N3)3(py)3,32 Na[Ga(N3)4]5, and
Ga(N3)3(NEt3).5 We suspect that these small derivations from
the typical azide geometry are caused by the effect of crystal
disorder in the structural analysis.
Acknowledgment. This work was supported by a grant from
the National Science Foundation (CHE-9616501). We also thank
Dr. Maren Pink for her work on solving the crystal structure of
H2GaN3(quin).
Figure 3. Structure of H[GaN(H)(2,6-iPr2C6H3)]2(quin) (3). The non-
hydrogen atoms are shown at the 50% probability level. The hydrogen
atoms except the hydride are omitted for clarity.
is shown in Figure 3. The two diisopropylphenyl groups were
oriented away from the quinuclidine ligand in such a manner
as to put the planes approximately parallel to one another. The
geometry for the amido nitrogens was more pyramidal with the
sum of the angles being 343 and 350°. The Ga-H bond length
was 1.47(2) Å.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of compounds 1-4. This
material is available free of charge via the Internet at http://pubs.acs.org.
IC9910110
Compound 4 crystallized in the space group P21/n with two
independent molecules in the asymmetric unit (Figure 4). Both
exhibited the same tetrahedral geometry about the Ga but
differed with respect to some of the bond lengths and angles.
The hydrido and azido ligands around Ga1 were disordered over
(30) Atwood, D. A.; Jones, R. A.; Cowley, A. H.; Atwood, J. L.; Bott, S.
G. J. Organomet. Chem. 1990, 394, C6-C8.
(31) Cowley, A. H.; Gabba¨ı, F. P.; Olbrich, F.; Corbelin, S.; Lagow, R. J.
J. Organomet. Chem. 1995, 487, C5-C7.
(32) Carmalt, C. J.; Cowley, A. H.; Culp, R. D.; Jones, R. A. J. Chem.
Soc., Chem. Commun. 1996, 1453-1454.