Synthesis and X-ray crystallographic structures of [HGa(NMe2)2]2 and [PhGa(NHNMe2)2]2, and room-temperature conversions of [HGa(NMe2)2]2 to (HGaNH)n and (HGaNMe)n

Article abstract of DOI:10.1016/j.jorganchem.2003.12.013

The reactivity of bis(dimethylamido) complexes of phenyl- and hydridogallium with ammonia, dimethylamine and 1,1-dimethylhydrazine is described. Synthesis of the starting gallium hydride, [HGa(NMe₂)₂]₂, was achieved in nearly quantitative yield from the reaction of HGaCl₂(quinuclidine) with LiNMe₂. In neat ammonia or methylamine at room temperature both dimethylamido ligands in [HGa(NMe₂) ₂]₂ were substituted by a single equivalent of NH₃ or MeNH₂ to produce amorphous (HGaNH)_n or (HGaNMe)_n, respectively. In contrast, the reaction of [PhGa(NMe₂)₂]₂ with neat Me₂NNH₂, at room temperature consumed two equivalents of the substituted hydrazine to form [PhGa(NHNMe₂)₂]₂ in a 73% yield. Single crystal X-ray crystallographic analyses of [HGa(NMe₂) ₂]₂ and [PhGa(NHNMe₂)₂] ₂ establish that in the solid state both compounds adopt a cyclic Ga-N-Ga-N structure with a crystallographic center of symmetry located at the center of the ring.

Full text of DOI:10.1016/j.jorganchem.2003.12.013

Journal of Organometallic Chemistry 689 (2004) 666–671
www.elsevier.com/locate/jorganchem
Synthesis and X-ray crystallographic structures of [HGa(NMe2)2]2
and [PhGa(NHNMe2)2]2, and room-temperature conversions
of [HGa(NMe2)2]2 to (HGaNH)n and (HGaNMe)n
*
Bing Luo, Wayne L. Gladfelter
Department of Chemistry, University of Minnesota, 207 Pleasant St., SE Minneapolis, MN 55455, USA
Received 17 October 2003; accepted 1 December 2003
Abstract
The reactivity of bis(dimethylamido) complexes of phenyl- and hydridogallium with ammonia, dimethylamine and 1,1-di-
methylhydrazine is described. Synthesis of the starting gallium hydride, [HGa(NMe2)2]2, was achieved in nearly quantitative yield
from the reaction of HGaCl2(quinuclidine) with LiNMe2. In neat ammonia or methylamine at room temperature both dimethy-
lamido ligands in [HGa(NMe2)2]2 were substituted by a single equivalent of NH3 or MeNH2 to produce amorphous (HGaNH)n or
(HGaNMe)n, respectively. In contrast, the reaction of [PhGa(NMe2)2]2 with neat Me2NNH2, at room temperature consumed two
equivalents of the substituted hydrazine to form [PhGa(NHNMe2)2]2 in a 73% yield. Single crystal X-ray crystallographic analyses
of [HGa(NMe2)2]2 and [PhGa(NHNMe2)2]2 establish that in the solid state both compounds adopt a cyclic Ga–N–Ga–N structure
with a crystallographic center of symmetry located at the center of the ring.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Gallium; Amide; Hydrazide; Hydride; Synthesis; Structure
i
½PhGaðNMe2Þ ꢀ þ BuNH2
1. Introduction
2 2
rt; 15h
½ðPhGaÞ ðNHiBuÞ ðNiBuÞ ꢀ ð51% yieldÞ ð2Þ
ꢀꢀꢀꢀ!
4
4
2
Amido and hydrazido gallium compounds have at-
tracted considerable attention, in part due to their po-
tential to act as precursors to gallium nitride [1–4].
Recent publications have highlighted the value of
bis(dimethylamido) complexes of hydrocarbylgallium,
[RGa(NMe2)2]2, as precursors to larger Ga–N clusters
and novel solid state materials [5,6]. These complexes
can be prepared in high yield, and their subsequent re-
actions with amines occur under mild conditions re-
leasing gaseous dimethylamine thus facilitating product
isolation (Eqs. (1)–(3)).
–Me2NH
½PhGaðNMe2Þ ꢀ þ MeNH2
2 2
ꢁ78 to rt
2h; –Me2NH
½ðPhGaÞ ðNHMeÞ ðNMeÞ ꢀ ð31% yieldÞ
ꢀꢀꢀꢀꢀ!
7
4
5
ð3Þ
In essence, [RGa(NMe2)2]2 serves as a useful synthon
for the ‘‘RGa2þ’’ moiety [7]. In this paper we report the
extension of this reaction to form a new bis(dimethylhyd-
razido) complex of phenylgallium. In addition, the syn-
thesis of [HGa(NMe2)2]2 is described and its reactivity
demonstrates an ability to serve as a source of ‘‘HGa2þ’’.
½EtGaðNMe2Þ ꢀ þ EtNH2
2 2
ꢁ78 to rt
2h; –Me2NH
½EtGaNEtꢀ ð56% yieldÞ
ð1Þ
ꢀꢀꢀꢀꢀ!
6
2. Results and discussion
2.1. [HGa(NMe2)2]2 (1)
* Corresponding author. Tel.: +1-612-624-4391; fax: +1-612-626-
8659.
E-mail address: gladfelt@chem.umn.edu (W.L. Gladfelter).
Compound 1 was synthesized nearly quantitatively as
a colorless crystalline solid from the reaction depicted in
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.12.013

B. Luo, W.L. Gladfelter / Journal of Organometallic Chemistry 689 (2004) 666–671
667
Eq. (4). The quinuclidine was easily removed by subli-
mation under vacuum. Compound 1 was characterized
by spectroscopic methods, elemental analysis
mers of 1 adopted a chair structure [8,11], we identified
four isomers with zero to three NMe2 ligands on gallium
in the axial positions. After ruling out those with two
and three NMe2 groups in axial positions due to steric
repulsions, the remaining two isomers would still afford
nine methyl resonances; three for the isomer without any
axial NMe2 groups (Scheme 1(c)) and six for the isomer
with one axial and two equatorial NMe2 ligands
(Scheme 1(d)). Despite the difficulty in characterizing all
of the isomers, their presence was further supported by
HGaCl2ðquinuclidineÞ þ 2LiNMe2
1
!
½HGaðNMe2Þ ꢀ þ LiCl þ quinuclidine
ð4Þ
2 2
2
and single-crystal XRD analysis. Its IR spectrum ex-
hibited a strong Ga–H stretching absorption at 1900
cmꢁ1. The base peak in the chemical-ionization mass
spectrum was the parent ion (plus 1) and the second
most intense ion was ð1 ꢁ NMe2Þþ.
1
the variable-temperature H NMR data. In spectra of a
toluene-d8 solution collected at temperatures from 20 to
100 °C, some coalescence occurred at temperatures
above 70 °C between peaks within each group. By 100
°C, however, three broad bridging and four terminal
NMe2 resonances remained indicating that isomeriza-
tion was slow compared to the NMR time scale.
1
The H NMR spectrum of 1 was surprisingly com-
plex. Two groups of peaks at 2.31–2.47 and 2.79–2.96
ppm comprised six and five intense singlets, respectively.
Several weak singlets were also observed in each group.
The total integrated areas for each of the two groups
were equal. Referenced to [RGa(NMe2)2]2 (R ¼ Me and
Et) [7], the resonances at 2.31–2.47 ppm were assigned to
the bridging NMe2 ligands, and at 2.79–2.96 ppm, to the
terminal NMe2 ligands. The singlets at 2.33 and 2.93
ppm, accounting for 60% of the total NMe2 resonances,
were assigned to the trans structure (Scheme 1(a)) found
in the solid state. We suggest that at least two additional
isomers were present in the solution. The only other
dimeric isomer, the cis dimer (Scheme 1(b)), if it existed
in solution as for [RGa(NMe2)2]2 (R ¼ Me and Et),
would only afford three singlets. Thus one or more of
the other isomer(s) shown in Scheme 1 must be pres-
ent, however, a specific assignment was not achieved.
It is known that some amido gallium compounds
including (H2GaNCH2CH2)3 [8], (Me2GaNH2)3 [9],
(tBu2GaNH2)3 [10] and (H2GaNH2)3 [11] are trimeric.
If trimeric isomers of 1 existed in solution, there would
be several possible isomers producing a number of
NMe2 resonances. For example, assuming that the tri-
2.2. [PhGa(NHNMe2)2]2 (2)
Compound 2 was isolated as colorless crystals in a
73% yield from the reaction shown in Scheme 2. In its
IR spectrum, the NH moieties were detected as a weak,
broad absorption at 3256 cmꢁ1. The trans dimeric
structure with intramolecular hydrogen bonds was
characterized by single-crystal XRD analysis.
1
The H NMR spectrum of 2 was consistent with the
solid-state structure. Two NH singlets were found at
3.64 and 4.05 ppm with the downfield resonance as-
signed as the hydrogen-bonded NH. The two chemically
inequivalent methyls were assigned to the two singlets at
2.51 and 2.62 ppm. The resonance for the NMe2 groups
on the bridging nitrogen atoms was located at 2.19 ppm
with its intensity being twice of each of the above two.
There were also three weak NMe2 peaks at 2.07, 2.25
and 2.28 ppm accounting for ca. 10% of the total NMe2
Scheme 1. Possible Isomers of [HGa(NMe2)2]2 (1).

668
B. Luo, W.L. Gladfelter / Journal of Organometallic Chemistry 689 (2004) 666–671
Scheme 2. Synthesis of [PhGa(NHNMe2)2]2 (2).
peak intensity. These resonances were attributed to an
isomer of 2 with one or more cis ligand orientations on
gallium or bridging nitrogen atoms. It was reported that
both trans and cis isomers were present in solutions for
known gallium hydrazide derivatives including (Me2
GaNHNMe2)2 [12] and (Me2GaNHNPh2)2 [13].
Perhaps due to the lack of volatility below its decom-
position temperature at 115 °C, the chemical-ionization
mass spectrum of 2 exhibited only a few low-mass peaks
(less than 117 amu). The only significant component was
Me2NNHþ3 and no gallium-containing fragments were
found, suggesting that the decomposition led to an in-
volatile residue. This same thermal sensitivity may have
contributed to the inaccurate C, H and N analyses.
The reaction of [PhGa(NMe2)2]2 with dimethylhy-
drazine was carried out to examine the possibility of
forming a gallium-nitrogen cluster in a similar route to
the transamination followed by amine elimination pro-
posed for the reactions of [RGa(NMe2)2]2 with primary
amines (Eqs. (1)–(3)). The result showed that neither full
nor partial dimethylhydrazine elimination occurred
from 2 at room temperature to produce [PhGa
(NNMe2)]n or [(PhGa)x(NHNMe2)y(NNMe2)z], re-
spectively. The reduced acidity of the dimethylhydrazido
ligand in 2 may retard the elimination reaction and
contribute to our ability to isolate this compound. Re-
acting [PhGa(NMe2)2]2 in refluxing H2NNMe2 at 80 °C
for 20 h did promote further reactions, but the products
were an uncharacterized mixture of a white precipitate
and a waxy, polymeric-like solid soluble in H2NNMe2.
Fig. 1. Molecular structure of 1. Atoms are shown at the 50% thermal
ellipsoid level, and the methyl hydrogen atoms are omitted for clarity.
2.3. Structural analyses of [HGa(NMe2)2]2 and
[PhGa(NHNMe2)2]2
Fig. 2. Molecular structure of 2. Atoms are shown at the 50% thermal
ellipsoid level, and all hydrogen atoms are omitted except H3N. The
dashed line indicates the H-bond between H3N and N2.
The structures of 1 and 2 are plotted in Figs. 1 and 2,
and the selected bond lengths and angles are listed in
Tables 2 and 3, respectively. Both compounds crystal-
ꢀ
ꢁ
were 2.0099(15) and 2.0230(15) A, respectively. The in-
lized in space group P1 with one-half of a molecule re-
siding in each asymmetric unit. Each molecule possessed
a crystallographically imposed inversion center at the
center of a planar Ga2N2 ring. The geometries of the
rings in 1 and 2 were typical for dimeric amido and hy-
drizido gallium compounds [2,3]. In 1, the terminal
ternal angle on Ga was 87.03(6)°. Within the group
of bis(dimethylamido) gallium compounds, [ClGa-
(NMe2)2]2 [14] has a trans solid-state structure while both
trans and cis structures for [MeGa(NMe2)2]2 [7] were
found in the solid state. For 2, the internal angle on Ga
(85.39(8)°) was very close to that found in (Et2GaN-
HNPh2)2 (85.8(3)°) [15]. The terminal Ga(1)–N(1) bond
ꢁ
Ga(1)–N(2) bond length was 1.8454(16) A and the
bridging Ga(1)–N(1) and Ga(1A)–N(1) bond lengths

B. Luo, W.L. Gladfelter / Journal of Organometallic Chemistry 689 (2004) 666–671
669
Table 1
Crystallographic data of [HGa(NMe2)2]2 (1) and [PhGa(NHNMe2)2]2
(2)
2.4. Conversions of
(HGaNMe)n (4)
1
to (HGaNH)n (3) and
Chemical formula
Formula weight
Space group
C8H26Ga2N4 (1)
317.77
C20H38Ga2N8 (2)
530.02
Compound 1 reacted in neat NH3 and MeNH2 at
temperatures up to room temperature affording white
solids 3 and 4, respectively (Eq. (5)). Based on earlier
studies of the reactions of [RGa(NMe2)2]2 with primary
amines [5,6], the reactions of 2 are proposed to proceed
through intermediates HGa(NH2)2 or HGa(NHMe)2
(or their ammonia or methyl amine adducts) followed
by NH3 or MeNH2 elimination (Eqs. (6) and (7)).
ꢀ
ꢀ
P1
P1
ꢁ
a (A)
6.2653(5)
7.0101(6)
8.6612(7)
81.805(2)
90.146(2)
76.7690(10)
354.02(5)
1
8.5628(5)
8.8245(5)
10.1905(6)
109.2530(10)
104.1150(10)
106.5850(10)
646.27(6)
1
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
3
ꢁ
V (A )
Z
½HGaðNMe2Þ ꢀ þ 2H2NR
2 2
T (°C)
)100
0.71073
)100
0.71073
ꢁ
! 2=nðHGaNRÞn þ 4HNMe2 R ¼ H ð3Þ and Me ð4Þ
ð5Þ
k (A)
qcalcd (g cmꢁ3
)
1.491
37.81
0.0201, 0.0483
1.362
21.06
0.0308, 0.0760
l (cmꢁ1
)
R1½I > 2rðIÞꢀ, wR2
(all data)a
P
½HGaðNMe2Þ ꢀ þ 6H2NR
2 2
n
P
P
2
a R1 ¼ jjFoj ꢁ jFcjj= jFoj
and
wR2 ¼
2
½wðFo2 ꢁ Fc2Þ ꢀ=
! 2HGaðNHRÞ ðH2NRÞ þ 4HNMe2
ð6Þ
2
ꢁ
o
1=2
P
2
½w Fo2Þ ꢀ
, where w ¼ 1=½r2ðFo2Þ þ ðaPÞ þ ðbPÞꢀ, P ¼ ðFo2 þ 2Fc2Þ=3
nHGaðNHRÞ ðH2NRÞ ! ðHGaNRÞn þ 2nH2NR ð7Þ
2
and a, b are constants.
Both 3 and 4 were insoluble in common organic
solvents. No NH absorptions were detected in the IR
spectrum of 4, and the IR spectrum of 3 was identical
to that reported for (HGaNH)n prepared from the
reaction of cyclotrigallazane (H2GaNH2)3 with super-
critical ammonia at 150 °C [16]. For 4, the mGaH ab-
sorption was found at 1874 cmꢁ1, almost the same
ꢁ
length was 1.845(2) A, identical to that in 1. Consistent
with the intramolecular hydrogen bonding (N(3)–
ꢁ
H(3N)ꢂ ꢂ ꢂN(2)), the Ga(1)–N(3) [1.9935(18) A] bond was
ꢁ
shorter than Ga(1A)–N(3) [2.0224(18) A] and the Ga(1)–
N(3)–H(3N) bond angle (106(2)°) was smaller than
Ga(1A)–N(3)–H(3N) (111.5(19)°).
Table 2
ꢁ
Selected bond lengths (A) and angles (°) for [HGa(NMe2)2]2 (1)
Ga(1)–N(1)
Ga(1A)–N(1)
2.0099(15)
2.0230(15)
Ga(1)–N(2)
Ga(1)–H(1)
1.8454(16)
1.45(2)
N(1)–Ga(1)–N(2)
N(1A)–Ga(1)–N(2)
N(2)–Ga(1)–H(1)
C(1)–N(1)–C(2)
114.75(7)
116.05(7)
113.6(9)
N(1)–Ga(1)–N(1A)
N(1)–Ga(1)–H(1)
N(1A)–Ga(1)–H(1)
C(1)–N(1)–Ga(1)
C(2)–N(1)–Ga(1)
Ga(1)–N(1)–Ga(1A)
C(3)–N(2)–Ga(1)
Angle sum on N(2)
87.03(6)
111.7(9)
111.0(9)
108.84(16)
113.74(11)
112.33(13)
111.62(17)
119.47(14)
111.69(12)
116.71(12)
92.97(6)
C(1)–N(1)–Ga(1A)
C(2)–N(1)–Ga(1A)
C(3)–N(2)–C(4)
127.09(13)
358.2(4)
C(4)–N(2)–Ga(1)
Table 3
Selected bond lengths (A) and angles (°) for [PhGa(NHNMe2)2]2 (2)
ꢁ
Ga(1)–N(1)
Ga(1)–N(3)
Ga(1)–C(1)
Ga(1A)–N(3)
N(1)–N(2)
1.845(2)
1.9935(18)
1.961(2)
N(3)–N(4)
1.449(3)
0.88(3)
2.67(3)
3.186(3)
N(3)–H(3N)
H(3N)ꢂ ꢂ ꢂN(2)
N(2)ꢂ ꢂ ꢂN(3)
2.0244(18)
1.425(3)
C(1)–Ga(1)–N(1)
C(1)–Ga(1)–N(3)
C(1)–Ga(1)–N(1A)
Ga(1)–N(3)–Ga(1A)
Ga(1)–N(3)–N(4)
Ga(1A)–N(3)–N(4)
Ga(1)–N(3)–H(3N)
Ga(1A)–N(3)–H(3N)
116.40(9)
120.01(8)
111.60(9)
94.61(8)
N(1)–Ga(1)–N(3)
N(1)–Ga(1)–N(3A)
N(3)–Ga(1)–N(3A)
N(4)–N(3)–H(3N)
Ga(1)–N(1)–N(2)
Ga(3)–N(1)–H(1N)
N(2)–N(1)–H(1N)
N(3)–H(3N)ꢂ ꢂ ꢂN(2)
103.76(9)
115.94(9)
85.39(8)
106.6(19)
117.18(15)
131(2)
117.18(14)
120.03(14)
106(2)
109(2)
118(2)
111.5(19)

670
B. Luo, W.L. Gladfelter / Journal of Organometallic Chemistry 689 (2004) 666–671
wave number as for 3 (1876 cmꢁ1). Good agreement
for carbon and hydrogen percentages was obtained in
the elemental analysis of 4, but the nitrogen percentage
was 1.2% lower than the calculated value possibly due
to the formation of involatile GaN in the analytical
process.
In earlier reports of the synthesis of (HGaNH)n in
supercritical ammonia at 150 °C the product gave rise to
distinct powder X-ray reflections that were assigned to
the hexagonal crystal system [16]. Powder XRD pattern
of 3 established that is was essentially amorphous. A
weak, broad reflection at 14° for 3 corresponded to the
most intense reflection observed in the more highly
crystalline samples prepared in the ammonothermal re-
action. The powder XRD pattern of 4 exhibited two
weak, broad reflections at 22° and 34° that also indi-
cated limited crystallinity. Higher reaction temperatures
are needed to facilitate the formation of crystals in these
oligo- or polymeric structures.
Desert Analytics, Tucson, AZ. Powder X-ray diffraction
experiments were conducted on a Siemens 5005 diffrac-
tometer using monochromatic (graphite) Cu Ka radia-
tion with a 45 kV source voltage and a 40 mA current.
The XRD patterns were collected over 2–50° in 2h with
a step of 0.05° and a dwell time of 2 s. In the experi-
ments, samples previously protected under nitrogen
were quickly placed onto sample holders in air and
mounted on the diffractomer. During data collection no
degradation was observed.
3.2. Synthesis of [HGa(NMe2)2]2 (1)
To a stirred slurry of LiNMe2 (4.16 g, 81.5 mmol) in
20 ml of Et2O at )78 °C was added dropwise a solution
of HGaCl2(quin) (10.30 g, 40.7 mmol) in 250 ml of Et2O.
The mixture was allowed to warm to room temperature
and stirred for 17 h. Volatiles were removed under vac-
uum affording a white solid. Pentane (100 ml) was added
and the resulting slurry was filtered to separate a white
solid (LiCl) and a colorless filtrate. After the filtrate was
concentrated to ca. 20 ml and stored at )20 °C overnight,
colorless plates were collected (6.28 g, 97% yield). Mp:
3. Experimental
3.1. Materials and general procedures
1
67.5–69.0 °C. H NMR (C6D6, 20 °C): d 2.33 (12H, s,
bridging NMe2), 2.93 (12H, s, terminal NMe2), 4.79 (2H,
br s, GaH). There were additional singlets at d 2.31, 2.35,
2.40, 2.41, 2.47, 2.79, 2.85, 2.89, 2.91 and 2.96, attrib-
Gallium chloride was purchased from Strem and used
as received. Other chemicals were obtained from Al-
drich. Anhydrous ammonia, methylamine and dimeth-
ylamine were used as received. Diethyl ether and
pentane were predried over calcium hydride and freshly
distilled over sodium/benzophenone under nitrogen.
Dimethylhydrazine, benzene-d6 and toluene-d8 were
distilled over CaH2 under nitrogen. The quinuclidine
dichlorogallane adduct, HGaCl2(quinuclidine) [17] and
bis(dimethylamido) phenylgallium, [PhGa(NMe2)2]2 [7]
were prepared as previously reported. LiNMe2 was
prepared as a white powder from the reaction of
HNMe2 with 1 equivalent of n-butyllithium in hexanes.
All experiments were conducted under an oxygen-free,
dry-nitrogen atmosphere using standard Schlenk and
glovebox techniques.
Proton NMR spectra were obtained in benzene-d6
solutions at room temperature and in toluene-d8 solu-
tions at higher temperatures on a Varian INOVA 300 or
a UNITY plus 500 spectrometer. The residual proton
(7.15 ppm) in benzene-d6 or the sharp singlet from sili-
con grease (0.29 ppm) for toluene-d8 solutions was used
as the internal standard. The IR spectra of KBr pellets
were recorded on a Nicolet MAGNA-IR 560 spec-
trometer. Chemical-ionization mass spectra were ac-
quired on a Finnigan Mat 95 spectrometer using a direct
insertion probe. The samples were evaporated at a
temperature range of 25–340 °C and the ionization gas
mixture was methane with 4% ammonia. Melting points
were measured in sealed glass capillaries and were un-
corrected. The elemental analyses were performed by
utable to isomers of 1 (see Section 2). IR (cmꢁ1): mGaH
,
1900. CI MS {assignment, % relative intensity}: 319
{(M + H)þ, 100}, 291 {(M ) NMe2 + NH3)þ, 16}, 274
{(M ) NMe2)þ, 61}, 231 {(0.5M + GaH2)þ, 5.5}, 176
{[0.5M + NH4)]þ, 2.4}, 159 {(0.5M + H)þ, 3.0}, 69
{Gaþ, 26}. Anal. Calc. for C8H26Ga2N4: C, 30.24; H,
8.25; N, 17.63. Found: C, 29.96; H, 8.34; N, 17.04.
3.3. Synthesis of [PhGa(NHNMe2)2]2 (2)
Excess H2NNMe2 (2.0 ml, 26 mmol) was added into a
flask containing [PhGa(NMe2)2]2 (1.00 g, 4.26 mmol) at
room temperature. Gas evolution was immediately ob-
served resulting in a colorless solution. The solution was
stirred for 2 h and volatiles were removed under vacuum
to give a white solid. Ether (15 ml) was added to dissolve
the solid and the solution was stored at )20 °C over-
night affording colorless blocks (0.82 g, 73% yield). Mp:
115–123 °C, decomp. 1H NMR: d 2.19 (12H, s, NMe2 of
the bridging NHNMe2), 2.51 and 2.62 (each 6H, s,
NMe2 of the terminal NHNMe2), 3.64 and 4.05 (each
2H, s, NH), 7.30, 7.37, 8.01 and 8.17 (total 10H, m, Ph).
Three additional NMe2 singlets at 2.07, 2.25 and 2.28
ppm accounting for ca. 10% of the total NMe2 peak
integration were attributed to an isomer of 2. IR (cmꢁ1):
3256. The CI MS and elemental analysis were unsatis-
factory. CI MS {assignment, % relative intensity}: 61
{Me2NNHþ3 , 100}. Other four masses, 87 (9% relative to

B. Luo, W.L. Gladfelter / Journal of Organometallic Chemistry 689 (2004) 666–671
671
mass 61 amu), 92 (3.5%) and 117 (2%) amu, were not
assigned.
performed to locate the remainder of the non-hydrogen
atoms. All non-hydrogen atoms were refined with an-
isotropic displacement parameters. For 1, the hydrogen
atom H(1) on gallium was found from the Fourier map
and all of the other hydrogen atoms were placed in ideal
positions. For 2, all of the hydrogen atoms were located
from the Fourier map and were refined isotropically.
The experimental conditions and unit cell information
are summarized in Table 1. The calculations were per-
formed using the SHELXTL V5.0 suite of programs.
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 222002 for 1 and No. 222003
for 2. Copies of this information may be obtained free of
charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ UK, Fax. (int. code)
+44(1223)336-033 or Email: deposit@ccdc.cam.ac.uk or
http://www.ccdc.cam.ac.uk.
3.4. Synthesis of (HGaNH)n (3)
Anhydrous ammonia (ca. 4 ml) was condensed into a
flask containing [HGa(NMe2)2]2 (0.500 g, 1.57 mmol) at
)196 °C. The mixture was placed in a 2-propanol/dry-
ice bath ()78 °C) and allowed to warm naturally to
room temperature. A white solid precipitated at low
temperatures and accumulated as liquid NH3 evapo-
rated. The solid was pumped for 0.5 h to remove re-
sidual NH3 and collected (0.25 g, 94% yield). The IR
spectrum of 3 was identical to that of the authentic
(HGaNH)n prepared from the reaction of (H2GaNH2)3
with NH3 at 150 °C [16]. IR (cmꢁ1): 3279 m (mNH), 1876
s (mGaH), 1510 w, 957 s, 901 s.
3.5. Synthesis of (HGaNMe)n (4)
MeNH2 (ca. 5 ml) was condensed into a flask con-
taining 1 (0.500 g, 1.57 mmol) at )78 °C. The mixture
was allowed to warm to room temperature and a white
solid precipitated. After all the amines evaporated and
the residue was pumped for 0.5 h, 4 (0.29 g, 92% yield)
was collected as a white powder. It was insoluble in
common organic solvents. IR (cmꢁ1): 2951 m, 2921 m,
2882 m, 2808 m, 1874 s (mGa–H), 1479 w, 1455 w, 1426 w,
1131 w, 1053 w, 971 s, 686 w. Anal. Calc. for
(CH4GaN)n: C, 12.04; H, 4.04; N, 14.04. Found: C,
11.92; H, 4.30; N, 12.86.
Acknowledgements
The authors gratefully acknowledge support from the
National Science Foundation (CHE-0315954). We also
thank Dr. Victor G. Young for his assistance with the
single crystal XRD experiments.
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ꢁ
ꢁ
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ꢀ
For both structures, the space group P1 was deter-
mined based on lack of systematic absences and on the
intensity statistics. Successful direct-methods solutions
were applied to both structures that provided most of
the non-hydrogen atoms from the E-maps. Several full-
matrix, least-squares/difference Fourier cycles were
[17] B. Luo, V.G. Young Jr., W.L. Gladfelter, Chem. Commun. (1999)
123.