The dihydronaphthalene elimination reaction as a route to gallium-nitrogen compounds. Crystal and molecular structure of [(PhMe2CCH2)2GaNHPh]2

Article abstract of DOI:10.1021/om9801249

The dihydronaphthalene derivative Na₂{C₁₀H₈[Ga(CH₂CMe ₂Ph)₂Cl]₂} reacts at room temperature with NH₃, n-PrNH₂, and PhNH₂ in THF solution to give high yields of [(PhMe₂-CCH₂)₂GaNHR]₂ (R = H, n-Pr, Ph), C₁₀H₁₀, and NaCl. In contrast, the elimination reactions between Ga(CH₂CMe₂Ph)₃ with these same amines to form [(PhMe₂CCH₂)₂GaNHR]₂ and PhCMe3 require temperatures of 150°C. The cyclopentadiene elimination reaction between (PhMe₂CCH₂)₂Ga(C₅H₅) and aniline occurs at -10°C and is the fastest of these three. An X-ray structural study of [(PhMe₂CCH₂)₂GaNHPh]₂ identified it as the trans isomer.

Full text of DOI:10.1021/om9801249

Organometallics 1998, 17, 3311-3315
3311
Th e Dih yd r on a p h th a len e Elim in a tion Rea ction a s a
Rou te to Ga lliu m -Nitr ogen Com p ou n d s. Cr ysta l a n d
Molecu la r Str u ctu r e of [(P h Me2CCH2)2Ga NHP h ]2
O. T. Beachley, J r.,* Matthew J . Noble, Melvyn Rowen Churchill,* and
Charles H. Lake
Department of Chemistry, State University of New York at Buffalo,
Buffalo, New York 14260-3000
Received February 20, 1998
The dihydronaphthalene derivative Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} reacts at room
temperature with NH3, n-PrNH2, and PhNH2 in THF solution to give high yields of [(PhMe2-
CCH2)2GaNHR]2 (R ) H, n-Pr, Ph), C10H10, and NaCl. In contrast, the elimination reactions
between Ga(CH2CMe2Ph)3 with these same amines to form [(PhMe2CCH2)2GaNHR]2 and
PhCMe3 require temperatures of 150 °C. The cyclopentadiene elimination reaction between
(PhMe2CCH2)2Ga(C5H5) and aniline occurs at -10 °C and is the fastest of these three. An
X-ray structural study of [(PhMe2CCH2)2GaNHPh]2 identified it as the trans isomer.
4
The hydrocarbon elimination reaction is of fundamen-
tal importance to group 13-15 chemistry.1 In its
simplest terms for nitrogen compounds, an amine ad-
duct can be converted by an elimination reaction to an
amide derivative, to an imide derivative and then to a
nitride:
CMe3 ) and amines and phosphines. These reactions
typically occur below room temperature or 100-200 °C
lower than the temperatures needed for reactions of
GaR3 with the same bases. In this paper, elimination
reactions of a diorganogallium derivative of dihydronaph-
thalene Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} are described.
The yellow dihydronaphthalene derivative5,6 Na2-
{C10H8[Ga(CH2CMe2Ph)2Cl]2}
MR3 + EH3 f R2MEH2 + RH
(1)
M ) group 13, E ) group 15 element
R2MEH2 f RMEH + RH
(2)
(3)
RMEH f ME + RH
Researchers have attempted to define the factors which
determine the temperatures necessary to initiate these
reactions, but without definitive success. Each succeed-
ing reaction in this sequence typically requires higher
temperatures. Since these reactions provide a direct
connection between group 13-15 chemistry and the
preparation of electronic materials such as GaN, InN,
GaAs, and InP, we have attempted to discover new
hydrocarbon elimination reactions which occur at tem-
peratures lower than those typically observed for the
simple homoleptic organogallanes and group 15 bases
(ER3-nHn: E ) N, P, As; n ) 1-3) because lower
reaction temperatures minimize the possibility of de-
composition reactions and, in turn, should lead to the
formation of purer materials. This goal was realized
with the discovery of the cyclopentadiene elimination
reaction between R2Ga(C5H5) (R ) Me,2 Et,3 and CH2-
reacts at room temperature with NH3, n-PrNH2, and
PhNH2 in THF solution to form [(PhMe2CCH2)2GaNHR]2
(R ) H, n-Pr, Ph) as colorless crystalline solids in high
yields, along with C10H10 and NaCl (eq 5). The time
2Ga(CH2CMe2Ph)2Cl + C10H8 + 2Na THF8
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} (4)
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} + 2RNH2 f
[(PhMe2CCH2)2GaNHR]2 + C10H8+ 2NaCl (5)
necessary for complete reaction, was indicated by the
change in color of the solution from bright golden yellow
to colorless at completion in all three cases. Aniline
reacted fastest and required approximately 6 h for
complete reaction, whereas n-propylamine, the strongest
base, was slowest and took 5 days. Ammonia required
(1) (a) Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds. Comprehen-
sive Organometallic Chemistry; Pergamon Press: Oxford, U.K., 1982;
Vol. 1, p 588, and references therein. (b) Coates, G. E., Green, M. L.
H., Wade, K., Eds. Organometallic Compounds; Methuen: London,
1967; Vol. 1, p 177, and references therein. (c) Cowley, A. H.; J ones,
R. H. Angew. Chem., Int. Ed. Engl. 1989, 28, 1208. (d) Schauer, S. J .;
Lake, C. H.; Watkins, C. L.; Krannich, L. K.; Powell, D. H. J .
Organomet. Chem. 1997, 549, 31 and references therein.
(3) Beachley, O. T., J r.; Rosenblum, D. B.; Churchill, M. R.; Lake,
C. H.; Toomey, L. M. Organometallics 1996, 15, 3653.
(4) Beachley, O. T., J r.; Maloney, J . P.; Rogers, R. D. Organometallics
1997, 16, 3267.
(5) Noble, M. J . Ph.D. Thesis, State University of New York at
Buffalo, 1994.
(2) Beachley, O. T., J r.; Royster, T. L., J r.; Arhar, J . R.; Rheingold,
A. L. Organometallics 1993, 12, 1976.
(6) Beachley, O. T., J r.; Pazik, J . C.; Noble, M. J . Organometallics
1994, 13, 2885.
S0276-7333(98)00124-1 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/26/1998

3312 Organometallics, Vol. 17, No. 15, 1998
Beachley et al.
4 days. The reaction of the neopentyl derivative
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} with ammonia,7 which
was described previously, required only 18 h to go to
completion. Thus, the neophyl derivative reacts sig-
nificantly slower than the neopentyl derivative.
Since
the
dihydronaphthalene
derivative
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} decomposes at room
temperature to form Ga(CH2CMe2Ph)3, [Ga(CH2CMe2-
Ph)]n, and NaCl, the question of whether [(PhMe2-
CCH2)2GaNHR]2 (R ) H, n-Pr, Ph) is formed by an
elimination reaction between the amine and
C10H8[Ga(CH2CMe2Ph)2]2 or from some other gallium
compounds which could be in solution must be ad-
dressed. All experimental data are consistent with the
conclusion that C10H8[Ga(CH2CMe2Ph)2]2 is the reactive
compound. The simple elimination reactions of Ga(CH2-
CMe2Ph)3 with the amines were studied independently
and found to require temperatures on the order of 150
°C to initiate elimination (eq 6). No reaction was
F igu r e 1. Packing diagram for [(PhMe2CCH2)2GaNHPh]2,
viewed down the a axis. The defined molecule 1 (centered
about 0, 1/2, 0) lies to the left, and molecule 2 (centered
about 1/2, 1/2, 1/2) is in the center of this diagram. (The c
axis is horizontal, and the b axis is vertical.)
characterized in this study, but only [(PhMe2CCH2)2-
GaNHPh]2 was characterized by an X-ray structural
determination. The products formed at room temper-
ature have sharper and slightly higher melting points
and are probably more pure than those formed in sealed
tubes at 140-150 °C. Cryoscopic molecular weight data
demonstrated the presence of dimers. 1H NMR spectral
data show the trans isomer being the predominant
species in benzene solution. The cis isomer was ob-
served in 7% abundance, but only in those benzene
solutions of [(PhMe2CCH2)2GaNHPh]2 which had been
prepared from the dihydronaphthalene derivative at
room temperature. A benzene solution of [(PhMe2-
CCH2)2GaNHPh]2 which had been prepared in a sealed
tube at 140-150 °C consisted of 100% trans isomer.
When the 1H NMR spectrum of a CH2Cl2 solution of
[(PhMe2CCH2)2Ga-NHPh]2 which had been prepared
by the dihydronaphthalene elimination reaction was
recorded, 16% cis isomer was observed. Benzene solu-
tions of [(PhMe2CCH2)2GaNH(n-Pr)]2 prepared by either
route contained only the 100% trans isomer.
Ga(CH2CMe2Ph)3 + RNH2 f
1/2[(PhMe2CCH2)2GaNHR]2 + PhCMe3 (6)
observed at room temperature. Second, if Ga(CH2CMe2-
Ph)3 had been formed from the decomposition of
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2}, [Ga(CH2CMe2Ph)]n,
a reddish brown compound,5,6 would also have been
formed. However, the solution changed from lemon
yellow to bright golden yellow to colorless and never was
reddish brown. These observations suggest that [Ga-
(CH2CMe2Ph)]n was not present. Furthermore, the
closely related low-oxidation-state gallium compound
[Ga(CH2CMe3)]n has been reacted with ammonia,7 but
temperatures around 450 °C were required to initiate
a reaction. The products were GaN, H2, and CMe4.
Third, the initial lemon yellow color is due to
Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2}. When the amine
was added, a colorless precipitate (assumed to be NaCl)
was formed and the color of the solution changed to
bright golden yellow. These observations are consistent
with the formation of an amine adduct, C10H8[Ga(CH2-
CMe2Ph)2]2‚2(amine), the species which eventually is
An X-ray structural study of [(PhMe2CCH2)2GaNHPh]2
showed the crystal to be composed solely of the trans
isomer. The crystallographic asymmetric unit consists
of half of each of two crystallographically independent
molecules, each of which lies about a center of sym-
metry. Molecule 1 lies at about 0, 1/2, 0 (Wyckoff
1
notation c), while molecule 2 lies at about 1/2, 1/2,
/
2
transformed into [(PhMe2CCH2)2GaNHR]2 and C10H10
.
(Wyckoff notation h).9 All molecules are separated by
normal van der Waals distances, and there are no
anomalously short intermolecular contacts (Figure 1).
The labeling scheme used for molecule 1 is shown in
Figure 2. Note that the two crystallographically inde-
pendent molecules are chemically equivalent and vary
only in minor differences of orientation about Ga-C or
Ga-N linkages. Bond distances and angles for both
molecules are presented in Tables 1 and 2, respectively.
The dihydronaphthalene elimination reaction be-
tween Na2{C10H8[Ga(CH2CMe2Ph)2Cl]2} and aniline
was compared directly with the cyclopentadiene elimi-
nation reaction between (PhMe2CCH2)2Ga(C5H5) and
aniline. The latter was prepared in situ by a stoichio-
metric ligand redistribution reaction between Ga(CH2-
CMe2Ph)3 and Ga(C5H5)3.4 After a stoichiometric amount
of aniline was added to the solution of (PhMe2CCH2)2-
Ga(C5H5), the reaction mixture was maintained at -10
°C, and after 24 h [(PhMe2CCH2)2GaNHPh]2, a slightly
soluble solid, was isolated in higher than 70% yield.
Thus, the unsymmetrically substituted neophylgallium
compounds (PhMe2CCH2)2GaC5H5 and [(PhMe2CCH2)2-
Ga]2(C10H8) both undergo elimination reactions with
amines at room temperature (or below) to form [(PhMe2-
CCH2)2GaNHR]n, but the cyclopentadiene elimination
reaction is faster.
The presence of centers of symmetry necessitates that
each Ga2N2 molecular core be strictly planar. Each four-
(8) Beachley, O. T., J r.; Noble, M. J .; Churchill, M. R.; Lake, C. H.
Organometallics 1992, 11, 1051.
(9) (a) International Tables for X-ray Crystallography, 2nd ed.;
Kynoch Press: Birmingham, U.K., 1965; Vol. 1, p 75. (b) A reviewer
suggested the possibility of “a monoclinic C-centered cell (11.054,
20.365, 20.502 Å, beta [sic] ) 96.5°”. If one doubles the b axis in our
present triclinic unit cell, there results a cell with a′ ) 11.0541(19) Å,
b′ ) 20.3671(44) Å, c′ ) 20.5098(36) Å, R′ ) 90.321(15)°, â′ ) 96.486-
(16), and γ′ ) 91.587(16)°. Both R′ and γ′ are significantly different
from 90°, and there is no evidence for 2/m symmetry of diffraction.
Furthermore, the completed structure (viz. Figure 1) shows no general
crystallographic relationship between molecule 1 and molecule 2. The
attribution of our crystal to the triclinic crystal class is thus secure.
Three gallium nitrogen compounds, [(PhMe2CCH2)2-
GaNHR]2 (R ) H, n-Pr,8 Ph), were prepared and
(7) Beachley, O. T., J r.; Pazik, J . C.; Noble, M. J . Organometallics
1998, 17, 2121.

A Route to Gallium-Nitrogen Compounds
Organometallics, Vol. 17, No. 15, 1998 3313
CCH2)2GaNH(n-Pr)]2.8 The Ga-N distances were
slightly shorter at 2.013(2) and 2.029(2) Å, and the
Ga2N2 molecular core was slightly more compact, with
the two Ga atoms separated by 2.938(1) Å and the two
nitrogen atoms by 2.776(3) Å. The internal ring angle
about Ga was 86.7(1)°, whereas that about N was 93.3-
(1)°.
Two neophyl ligands are bound to each gallium(III)
center with Ga(1)-C(00) ) 1.967(6) Å and Ga(1)-C(10)
) 1.982(5) Å and an interligand angle of C(00)-Ga(2)-
C(10) ) 123.5(2)° (Ga(2)-C(30) ) 1.988(5) Å, Ga(2)-
C(40) ) 1.982(5) Å, and C(30)-Ga(2)-C(40) ) 122.2(2)°
for the second molecule). The Ga-C distances for
[(PhMe2CCH2)2GaNH(n-Pr)]28 were 1.992(2) and 1.994-
(3) Å. The twist associated with the neophyl ligands
for [(PhMe2CCH2)2GaNHPh]2 in relation to the molec-
ular core is 89.3°, as defined by the intercept of the
planes C(00)-Ga(1)-C(10) and N(3)-Ga(1)-N(3A)
(C(30)-Ga(2)-C(40)/N(4)-Ga(2)-N(4A) ) 88.1° for the
second molecule). The R-carbon atoms of the neophyl
ligands possess a distorted-tetrahedral environment
with expanded Ga-C(R)-C(â) angles of 116.6(3)-
119.9(4)°.
F igu r e 2. Labeling of atoms for molecule 1 of [(PhMe2-
CCH2)2GaNHPh]2 (ORTEP2 diagram, 30% probability el-
lipsoids for non-hydrogen atoms, all hydrogen atoms ar-
tifically reduced).
Ta ble 1. Selected Bon d Dista n ces (Å) for
[(P h Me2CCH2)Ga NHP h ]2
molecule 1
molecule 2
Primary phenyl amide ligands bridge the gallium(III)
metal centers. The nitrogen atoms of these ligands
possess a distorted-tetrahedral environment (Table 2b).
The hydrogen atoms of the amine moieties were located
and refined, successfully yielding N-H distances of
0.89(6) and 0.81(5) Å, respectively, for H(3) and H(4).
The N-H distance in [(PhMe2CCH2)2GaNH(n-Pr)]2 was
0.82(3) Å.8 The phenyl ring is bonded to the nitrogen
atom with N(3)-C(21) ) 1.437(8) Å (N(4)-C(51) )
1.436(7) Å). The phenyl rings intercept the plane of the
molecular core at 85.8 and 81.6° for molecules 1 and 2,
respectively (intercept of the planes Ga(1)-N(3)-Ga-
(1A)/C(21)-C(22)-C(23) and Ga(2)-N(4)-Ga(2A)/C(51)-
C(52)-C(53)). The phenyl rings are close to parallel and
are perpendicular to the appropriate Ga‚‚‚Ga axis, an
orientation resulting from the arrangement of the
neophyl ligands about the molecular core.
(a) Distances Associated with the Gallium(III) Atoms
Ga(1)-N(3)
2.082(4)
1.977(6)
1.982(5)
3.008(1)
2.037(3)
Ga(2)-N(4)
2.066(4)
1.988(5)
1.982(5)
3.018(1)
2.037(5)
Ga(1)-C(00)
Ga(1)-C(10)
Ga(1)‚‚‚Ga(1A)
Ga(1)-N(3A)
Ga(2)-C(30)
Ga(2)-C(40)
Ga(2)‚‚‚Ga(2A)
Ga(2)-N(4A)
(b) Bond Lengths within the Bridging Amide Ligands
N(3)-H(3)
0.89(6)
N(4)-H(4)
0.81(5)
N(3)-C(21)
N(3)-Ga(1A)
C(21)-C(22)
C(21)-C(26)
C(22)-C(23)
C(23)-C(24)
C(24)-C(25)
C(25)-C(26)
1.437(8)
2.037(3)
1.375(9)
1.377(6)
1.389(10)
1.392(8)
1.358(13)
1.368(10)
N(4)-C(51)
N(4)-Ga(2A)
C(51)-C(52)
C(51)-C(56)
C(52)-C(53)
C(53)-C(54)
C(54)-C(55)
C(55)-C(56)
1.436(7)
2.037(5)
1.365(7)
1.392(9)
1.397(10)
1.370(13)
1.365(9)
1.375(9)
Ta ble 2. Selected Bon d An gles (d eg) for
[(P h Me2CCH2)Ga NHP h ]2
molecule 1
molecule 2
Exp er im en ta l Section
(a) Angles around the Gallium(III) Centers
N(3)-Ga(1)-C(00)
N(3)-Ga(1)-C(10)
108.5(2) N(4)-Ga(2)-C(30)
107.8(2) N(4)-Ga(2)-C(40)
106.1(2)
109.9(2)
All compounds described in this investigation were very
sensitive to oxygen and moisture and were manipulated under
a purified argon atmosphere in a Vacuum Atmospheres drybox
equipped with a Dri-Train or by using standard vacuum line
techniques. The reagents Ga(CH2CMe2Ph)3 and Ga(CH2CMe2-
Ph)2Cl were prepared by using literature procedures.8 All
solvents were purified before use. Elemental analyses were
performed by E+R Microanalytical Laboratories, Corona, NY.
The 1H NMR spectra were recorded at 400 MHz by using a
Varian VXR-400 spectrometer with samples in flame-sealed
NMR tubes. Chemical shifts are reported in δ (ppm) and are
referenced to tetramethylsilane (TMS) at δ 0.00 ppm and
benzene at δ 7.15 ppm. Infrared spectra of Nujol mulls
between CsI plates were recorded by means of a Perkin-Elmer
683 spectrometer. Melting points were observed with a Mel-
Temp by using flame-sealed capillaries and are uncorrected.
Molecular weights were measured cryoscopically in benzene
by using an instrument similar to that described by Shriver
and Drezdzon.10
C(00)-Ga(1)-C(10) 123.5(2) C(30)-Ga(2)-C(40) 122.2(2)
N(3)-Ga(1)-N(3A)
C(00)-Ga(1)-N(3A) 111.5(2) C(30)-Ga(2)-N(4A) 113.6(2)
C(10)-Ga(1)-N(3A) 112.6(2) C(40)-Ga(2)-N(4A) 113.0(2)
86.2(1) N(4)-Ga(2)-N(4A)
85.3(2)
(b) Angles around the Nitrogen Atoms
Ga(1)-N(3)-Ga(1A)
93.8(1) Ga(2)-N(4)-Ga(2A)
94.7(2)
118.7(3)
Ga(1)-N(3)-C(21)
117.6(3) Ga(2)-N(4)-C(51)
Ga(1A)-N(3)-C(21) 125.2(3) Ga(2A)-N(4)-C(51) 123.8(3)
Ga(1)-N(3)-H(3)
Ga(1A)-N(3)-H(3)
C(21)-N(3)-H(3)
96(3)
113(4)
107(4)
Ga(2)-N(4)-H(4)
Ga(2A)-N(4)-H(4)
C(51)-N(4)-H(4)
102(3)
107(4)
108(4)
(c) Angles about C(R) of the Neophyl Groups
Ga(1)-C(00)-C(01) 119.9(4) Ga(2)-C(30)-C(31) 116.6(3)
Ga(1)-C(10)-C(11) 118.3(4) Ga(2)-C(40)-C(41) 119.3(4)
membered ring is slightly distorted from its possible D2h
symmetry. Gallium-nitrogen bond lengths range from
2.037(3) Å to 2.082(4) Å. The cross-ring distances
associated with the Ga2N2 molecular core are Ga-
(1)‚‚‚Ga(1A) ) 3.008 Å and N(3)‚‚‚N(3A) ) 2.815 Å
(3.018 and 2.780 Å, respectively, for the second mol-
ecule). These data may be compared with the corre-
sponding data for the closely related compound [(PhMe2-
Rea ction of Na 2{C10H8[Ga (CH2CMe2P h )2Cl]2} w ith An -
h yd r ou s Am in es. In a typical experiment the yellow gallium-
(10) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Compounds; Wiley: New York, 1986; p 38.

3314 Organometallics, Vol. 17, No. 15, 1998
Beachley et al.
3
(III) dihydronaphthalene derivative5,6 Na2{C10H8[Ga(CH2CMe2-
Ph)2Cl]2} was prepared in a Solv-Seal reaction flask at -78
°C from sodium metal, naphthalene, and Ga(CH2CMe2Ph)2Cl
and 40-50 mL of THF. Then, a slight excess of the dry amine
was added to the flask by vacuum distillation and the solution
was warmed from -196 to -78 °C. A large amount of colorless
precipitate (NaCl) formed as the solution became bright yellow.
Finally, the reaction mixture was warmed with stirring to
ambient temperature over 12 h. When reaction with the
amine was complete, the mixture was colorless. THF and the
other readily volatile materials were removed by vacuum
distillation at 20 °C. After the bulk of the readily volatile
material had been removed, the material remaining in the
flask was subjected to dynamic vacuum for 24 h. The slightly
volatile materials were collected in a small preweighed trap,
o-Ar (N-Ph), J CCH ) 8.80 Hz), 3.15 (s br, 2.1 H, -NH (trans
2
-
+ cis)), 1.07 (d, 4.0 H, -CH2 (trans), J CH ) 13.6 Hz), 1.03 (s,
12.0 H, -CMe2 (trans)), 1.01 (s, 12.9 H, -CMe2 (trans + cis)),
2
1
-
0.77 (d, 3.8 H, -CH2 (trans), J CH ) 13.6 Hz). The H NMR
spectrum for a C6D6 solution indicated an isomer distribution
of 7% cis and 93% trans ((5%). 1H NMR (CD2Cl2, δ): 7.34,
7.33, 7.30, 7.28, 7.25, 7.15 (m, 24 H, o-Ar (neophyl), m-Ar
(neophyl), p-Ar (neophyl), m-Ar (N-Ph)), 6.99 (t, 2 H, p-Ar (N-
Ph), 3J CCH ) 6.00 Hz), 6.55 (d, 4 H, o-Ar (N-Ph), 3J CCH ) 7.30
Hz), 2.94 (s br, 2.5 H, -NH (trans + cis)), 1.22 (s, 2.30 H,
-
-CMe2 (cis)), 1.02 (s, 0.70 H, -CH2 (cis)), 0.96 (s, 25.9 H,
-CMe2 (trans + cis)), 0.87 (d, 4.2 H, -CH2 (trans), J CH
2
-
)
-
-
13.7 Hz), 0.82 (s, 0.70 H, -CH2 (cis)), 0.58 (d, 4.2 H, -CH2
(trans), 2J CH ) 14.3 Hz). The 1 H NMR spectrum for the CH2-
Cl2 solution indicated an isomer distribution of 16% cis and
84% trans ((5%). IR (Nujol mull, cm-1): 3275 (s), 3082 (s),
3055 (s), 3015 (s), 2721 (m), 1949 (m), 1871 (m), 1809 (m), 1750
(m), 1595 (s), 1585 (sh, s), 1575 (m), 1489 (vs), 1279 (m), 1231
(s), 1210 (vs), 1175 (s), 1155 (m), 1139 (m), 1100 (m), 1070 (s),
1025 (s), 998 (m), 963 (m), 905 (m), 892 (s), 868 (sh, m), 862
(s), 852 (sh, m), 839 (m), 811 (m), 761 (vs), 750 (s), 725 (s), 712
(m), 699 (sh, vs), 692 (vs), 681 (sh, s), 665 (sh, m), 626 (m),
602 (w), 569 (m), 555 (m), 535 (w), 512 (w), 430 (sh, w), 418
(m), 408 (m), 250 (w), 235 (m). Anal. Calcd for C26H32GaN:
C, 72.92; H, 7.53. Found: C, 72.82; H, 7.59. Solubility:
soluble in THF; slightly soluble in pentane, benzene, toluene,
and m-xylene. The compound had insufficient solubility in
benzene for a cryoscopic molecular weight study.
R ea ct ion s of Ga (CH 2CMe2P h )3 w it h NH 3 a n d w it h
P h NH2. In a typical experiment a break-seal reaction tube
was charged with Ga(CH2CMe2Ph)3 and the amine, evacuated,
sealed, and then heated for 4 days at 140-150 °C. After no
noncondensable gas was observed to have been formed during
the reaction by using the vacuum line, the more volatile
product C6H5CMe3 was transferred to an NMR tube by vacuum
distillation at ambient temperature and identified as tert-
1
and the components were identified by H NMR spectroscopy
as C10H10, C10H8, and THF. The nonvolatile material was
extracted with pentane in order to separate NaCl from the
soluble gallium-nitrogen product. The latter was purified and
then fully characterized. The following paragraphs give
quantities of reactants, the time required at room temperature
for complete reaction, quantities and percent yields of products,
and the characterization data for each colorless new compound.
[(P h Me2CCH2)2Ga NH2]2. Reagents: 0.0926 g of Na (4.03
mmol), 0.517 g of C10H8 (4.03 mmol); 1.49 g of Ga(CH2CMe2-
Ph)2Cl (4.00 mmol), 4.22 mmol of NH3. Time at 20 °C for
complete reaction: 4 days. Products: 0.231 g of NaCl (3.95
mmol, 98.9% yield based on Na; see eq 1), 1.30 g of (PhMe2-
CCH2)2GaNH2 (3.69 mmol, 92.2% yield based on Ga(CH2CMe2-
Ph)2Cl (eq 1), product purified by recrystallization from
pentane at -30 °C). Mp: 99.1-101.1 °C. 1H NMR (C6D6, δ):
3
3
7.16 (d, 4 H, o-Ar, J CCH ) 7.59 Hz), 7.04 (t, 4 H, m-Ar, J CCH
3
) 6.26 Hz), 6.90 (t, 2 H, p-Ar, J CCH ) 6.33 Hz), 1.20 (s, 12 H,
-CMe2), 0.53 (s, 4 H, -CH2 ), -0.94 (s, 1 H, -NH2). IR (Nujol,
-
cm-1): 3378 (vs), 3310 (s), 3080 (s), 3075 (s), 3019 (s), 1951
(sh, m), 1943 (m), 1882 (m), 1867 (m), 1800 (m), 1744 (m), 1670
(m), 1597 (s), 1587 (m), 1275 (s), 1178 (s), 1155 (m), 1130 (m),
1098 (m), 1069 (s), 1061 (sh, s), 1027 (s), 998 (m), 960 (m), 942
(m), 925 (m), 901 (m), 848 (m), 848 (m), 838 (s), 821 (vs), 775
(m), 762 (vs), 715 (vs), 692 (vs), 635 (s), 615 (sh, m), 605 (sh,
m), 585 (m), 554 (s), 508 (w), 445 (s), 269 (w). Anal. Calcd for
1
butylbenzene by H NMR spectroscopy. The remaining color-
less solid was washed out of the reaction tube with ∼50 mL of
pentane through a medium-porosity glass frit, purified by
recrystallization from pentane, and identified.
[(P h Me2CCH2)2Ga NH2]2. Reagents: 2.31 g of Ga(CH2-
CMe2Ph)3 (4.93 mmol), NH3 (5.01 mmol). Products: 0.317 g
of C6H5CMe3 (4.40 mmol, 93.2% yield based on Ga(CH2CMe2-
Ph)3), 1.64 g of (PhMe2CCH2)2GaNH2 (4.64 mmol, 94.2% based
on Ga(CH2CMe2Ph)3). Mp: 94.3-97.3 °C. Anal. Calcd for
C
20H28GaN: C, 68.21; H, 8.01. Found: C, 68.14; H, 7.98.
Solubility: soluble in THF, pentane, and benzene.
[(P h Me2CCH2)2Ga NH(n -P r )]2. Reagents: 0.117 g of Na
(5.09 mmol), 0.653 g of C10H8 (5.09 mmol); 1.86 g of Ga(CH2-
CMe2Ph)2Cl (5.00 mmol), 0.301 g of n-PrNH2 (5.09 mmol). Time
at 20 °C for complete reaction: 5 days. Products: 0.264 g of
NaCl (4.52 mmol, 90.3% yield based on Na; eq 1), 1.67 g of
(PhMe2CCH2)2GaNH(n-Pr) (4.23 mmol, 84.6% yield based on
Ga(CH2CMe2Ph)2Cl, after product purified by recrystallization
from pentane at -30 °C). Mp: 127.8-128.5 °C (lit.8 mp 129.3-
131.0 °C). 1H NMR (C6D6, δ): 7.35 (d, 4 H, o-Ar, 3J CCH ) 8.10
C
20H28GaN: C, 68.21; H, 8.01. Found: C, 68.48; H, 7.96.
Cryoscopic molecular weight, benzene solution, formula weight
352.17 (obsd molality, obsd mol wt, association): 0.0909, 686,
1.95; 0.0721, 695, 1.98; 0.0550, 708, 2.01. Spectroscopic data
for this sample were identical within normal experimental
error with the data for the compound prepared by the reaction
of C10H8[Ga(CH2CMe2Ph)2]2 with NH3. Solubility: soluble in
pentane and benzene.
3
Hz), 7.16 (t, 4 H, m-Ar, J CCH ) 7.26 Hz), 7.00 (t, 2 H, p-Ar,
3
3
-
J CCH ) 7.14 Hz), 2.06 (q, 2 H, -CH2 (Pr), J CCH ) 7.68 Hz),
[(P h Me2CCH2)2Ga NHP h ]2. Reagents: 2.20 g of Ga(CH2-
CMe2Ph)3 (4.69 mmol); 0.503 g of PhNH2 (5.40 mmol). Prod-
ucts: 1.36 g of (PhMe2CCH2)2GaNHPh (3.18 mmol, 67.8% yield
based on Ga(CH2CMe2Ph)3). Mp: 174.1-177.0 °C. Spectro-
scopic data for this sample were identical within normal
experimental error with the data for the compound prepared
from the reaction of C10H8[Ga(CH2CMe2Ph)2]2 with PhNH2.
Only the trans isomer was observed by 1H NMR spectroscopy.
Syn th esis of (P h Me2CCH2)2Ga NHP h by Rea ctin g Ga -
(C5H5)3, Ga (CH2CMe2P h )3, a n d P h NH2. A reaction flask
was charged with Ga(CH2CMe2Ph)3 (1.46 g, 3.11 mmol), Ga-
(C5H5)3 (0.411 g, 1.55 mmol), and 20-25 mL of pentane. After
the solution had been stirred for 1 h at 20 °C, the flask was
cooled to -10 °C and a solution of PhNH2 (0.434 g, 4.66 mmol)
in 20 mL of pentane was added slowly. This solution was
stirred for an additional 24 h, and a large amount of colorless
precipitate, the slightly soluble product, formed. After the
pentane was removed by vacuum distillation, the residue was
-
1.33 (s, 12 H, -CMe2 (neophyl)), 0.87 (s, 4 H, -CH2 (neophyl)),
3
-
0.82 (m, 2 H, -NCH2 (Pr)), 0.61 (t, 3 H, -CH3 (Pr), J CCH
)
7.14 Hz), - 0.04 (t, 1 H, -NH, 3J CNH ) 7.50 Hz). The H NMR
spectrum indicated 100% trans isomer. Solubility: soluble in
THF, pentane, and benzene.
1
[(P h Me2CCH2)2Ga NHP h ]2. Reagents: 0.115 g of Na (5.01
mmol), 0.643 g of C10H8 (5.01 mmol); 1.86 g of Ga(CH2CMe2-
Ph)2Cl (5.00 mmol), 0.480 g of PhNH2 (5.15 mmol). Time at
20 °C for complete reaction: 6 h. Products: 0.272 g of NaCl
(4.65 mmol, 93.1% yield based on Na; eq 1), 1.75 g of (PhMe2-
CCH2)2GaNHPh (4.08 mmol, 81.6% yield based on Ga(CH2-
CMe2Ph)2Cl after product purified by recrystallization from
toluene at -78 °C). Mp: 175.4-177.5 °C. 1H NMR (C6D6, δ)
3
7.30 (d, 8 H, o-Ar (neophyl), J CCH ) 7.60 Hz), 7.20 (t, 4 H,
3
m-Ar (N-Ph), J CCH ) 6.80 Hz), 7.17 (t, 8 H, m-Ar (neophyl),
3
3J CCH ) 7.40 Hz), 7.03 (t, 4 H, p-Ar (neophyl), J CCH ) 7.20
3
Hz), 6.85 (t, 2 H, p-Ar (N-Ph), J CCH ) 7.40 Hz), 6.78 (d, 4 H,

A Route to Gallium-Nitrogen Compounds
Organometallics, Vol. 17, No. 15, 1998 3315
Ta ble 3. Da ta for th e X-r a y Cr ysta llogr a p h ic
Stu d ies of [(P h Me2CCH2)Ga NHP h ]2
washed numerous times with fresh pentane at low tempera-
ture (-40 to -78 °C) to remove impurities. The resulting
colorless solid was identified as pure (PhMe2CCH2)2GaNHPh
(1.41 g, 3.30 mmol, 70.8% yield based on Ga(CH2CMe2Ph)3).
Crystallographic quality crystals were obtained by slowly
cooling to ambient temperature a heated, saturated solution
of the compound in m-xylene. The crystals were mounted
directly from the m-xylene solution.
mol formula
cryst syst
C52H64Ga2N2
triclinic
space group
a, Å
b, Å
c, Å
P1h (No. 2)
11.0545(19)
11.4532(22)
20.5023(36)
86.599(15)
83.524(14)
62.713(13)
2292.11(73)
2
R, deg
[(P h Me2CCH2)2Ga NHP h ]2. Mp: 173.6-176.0 °C. 1H
NMR (C6D6, δ) (400 MHz): 7.28 (d, 8.0 H, o-Ar (neophyl), 3J CCH
) 8.0 Hz), 7.19 (t, 4.0 H, m-Ar (N-Ph), 3J CCH ) 7.80 Hz), 7.17
(t, 8.0 H, m-Ar (neophyl), 3J CCH ) 7.80 Hz), 7.02 (t, 4.0 H, p-Ar
(neophyl), 3J CCH ) 7.40 Hz), 6.84 (t, 2.0 H, p-Ar (N-Ph), 3J CCH
) 7.40 Hz), 6.76 (d, 4.0 H, o-Ar (N-Ph), 3J CCH ) 8.00 Hz), 3.14
â, deg
γ, deg
V, Å3
Z
mol wt
856.5
1.240
1.204
904
D, g cm-3
µ(Mo KR), mm-1
F(000)
2
-
(s br, 2.0 H, -NH (trans)), 1.06 (d, 3.9 H, -CH2 (trans), J CH
) 14.0 Hz), 1.02 (s, 11.8 H, -CMe2 (trans)), 1.00 (s, 11.8 H,
2
2θ range, deg
5-45
-
-CMe2 (trans)), 0.76 (d, 3.9 H, -CH2 (trans), J CH ) 13.6 Hz).
h
0-11
Only the trans isomer was observed by 1H NMR spectroscopy.
Anal. Calcd for C26H32GaN: C, 72.92; H, 7.53. Found: C,
72.93; H, 7.44. Solubility: slightly soluble in pentane, ben-
zene, and m-xylene.
k
l
-10 to +12
-21 to +22
6373
6004 (Rint )1.23%)
3711
semiempirical
0.5747/0.7027
σ2(F) + 0.0013F2
514
R ) 6.94
Rw ) 5.65
R ) 3.43
Rw ) 3.62
0.93
no. of rflns collected
no. of indep reflns
no. of rflns above 6σ
abs cor
min/max transmission
weighting scheme, w-1
no. of params refined
final R indices (all data), %
Collect ion of X-r a y Diffr a ct ion Da t a for [(P h Me2-
CCH2)2Ga NHP h ]2. A well-defined crystal of approximate
orthogonal dimensions 0.30 × 0.25 × 0.15 mm was sealed into
a thin-walled glass capillary under an argon atmosphere inside
the drybox maintained under anaerobic and moisture-free
conditions. The crystal was inspected under a binocular
microscope to ensure that it was indeed a single crystal and
then was centered on a Siemens R3m/V automated four-circle
diffractometer. The unit cell parameters were determined as
described previously.11 Intensity data (Mo KR radiation, λ )
0.710 730 Å)12 were collected at ambient temperature (25 ( 1
°C) with graphite-monochromatized radiation. The observed
Laue symmetry (Ci or 1h only) and the nonoccurrence of
systematic absences indicate that the crystal belongs to the
triclinic system. The centrosymmetric space group P1h (No. 2)
was selected on the basis of intensity statistics and frequency
of occurrence13 and was confirmed by the successful solution
of the structure. A total of 6373 reflections were collected and
merged to yield 6004 unique reflections, 3711 of which (61.8%)
had |Fo| > 6.0σ(Fo). Details appear in Table 3.
R indices (6σ data), %
goodness of fit
largest and mean ∆/σ
data-to-param ratio
largest diff peak, e Å-3
largest diff hole, e Å-3
0.002, 0.001
11.7:1
0.42
-0.42
syntheses, and least-squares refinement. Positional and
anisotropic thermal parameters for the unique N-bonded
hydrogen atom of each independent phenylamido group were
also refined; all remaining hydrogen atoms were placed in
calculated positions, based upon d(C-H) ) 0.96 Å17 and the
appropriate idealized trigonal or staggered-tetrahedral geom-
etry. Refinement of the ordered model converged with R )
3.43% and Rw ) 3.62% for those 3711 data with |Fo| > 6.0σ-
(|Fo|), and R ) 6.94% for all data.
Det er m in a t ion of Cr yst a l St r u ct u r e of [(P h Me2C-
CH2)2Ga NHP h ]2. All crystallographic calculations were car-
ried out on a VAX station computer with the use of the
Siemens SHELXTL PLUS (Release 4.11 (VMS)) program
package.14,15 The analytical expressions of the scattering
factors for neutral atoms16a were corrected for the ∆f ′ and i∆f ′′
components of anomalous dispersion.16b The structure was
solved via a combination of Patterson maps, difference Fourier
Ack n ow led gm en t. This work was supported in part
by the Office of Naval Research (O.T.B.). The purchase
of the X-ray diffractometer was made possible by Grant
89-13733 from the Chemical Instrumentation Program
of the National Science Foundation.
(11) Churchill, M. R.; Lashewycz, R. A.; Rotella, F. J . Inorg. Chem.
1977, 16, 265.
Su p p or tin g In for m a tion Ava ila ble: A figure showing
the labeling of atoms in molecule 2 and complete tables of
positional parameters, interatomic distances and angles,
anisotropic thermal parameters, and calculated positions for
hydrogen atoms for the X-ray study (11 pages). Ordering
information is given on any current masthead page.
(12) Bearden, J . A. Rev. Mod. Phys. 1967, 39, 78.
(13) Nowacki, W.; Matsumato, T.; Edenharter, A. Acta Crystallogr.
1967, 22, 935.
(14) Sheldrick, G. M. SHELXTL PLUS, Release 4.11 (VMS); Siemens
Analytical Instrument Corp., Madison, WI, 1989.
(15) Sheldrick, G. M. SHELXTL PLUS, An Integrated System for
Solving, Refining and Displaying Crystal Structures from Diffraction
Data; University of Go¨ttingen, Go¨ttingen, Germany, 1987 (for Nicolet
R3m/V).
OM9801249
(16) (a) International Tables for X-ray Crystallography; Kynoch
Press: Birmingham, England, U.K., 1974; Vol. 4, pp 99-101. (b) Ibid.,
pp 149-150.
(17) Churchill, M. R. Inorg. Chem. 1973, 12, 1213.