2
984 Inorganic Chemistry, Vol. 49, No. 6, 2010
Fan et al.
Experimental Section
0.46) suggested the presence of a second component (∼20%).
Recrystallization from hot hexane/toluene mixture gave crystal-
line samples containing 2 and 3. The more blocky morpho-
logy crystals were identified by single crystal X-ray diffraction
analysis as 3.
General Information. Inert atmosphere methods were used for
the handling of all reagents, and solvents were rigorously dried
and stored protected by dry nitrogen. Infrared spectra were
recorded on a Nicolet 6000 FT-IR spectrometer from KBr
pellets. Mass spectra were obtained with a Finnegan 4500 mass
spectrometer by using a solids inlet probe. NMR spectra were
recorded on Bruker AC-250 and JEOL-400 spectrometers.
3 3
Reaction of Me Al with PMAB. A sample of Me Al (5 mL,
2
.0 M solution in toluene, 10 mmol) was added dropwise to a
solution of PMAB (1.7 g, 10 mmol) in toluene (30 mL) at 23 °C.
1
13
11
The reaction mixture was stirred (15 h) and evolved CH was
4
4 3 2
Spectral standards were Me Si ( H, C) and F B OEt ( B).
3
collected and identified by IR spectroscopy. Solvent was eva-
porated leaving a white residue. Recrystallization from hexane
produced colorless crystalline [Me AlN(H)Me B N Me ] (4).
The (Me Si) Al OEt complex was prepared as described in the
2
3
1
3
3
5
literature and Me
Aldrich. The 1,3,4,5,6-pentamethyl-2-aminoborazine (PMAB)
3 3 3
Al, Et Al, and i-Bu Al were purchased from
2
2
3
3
3 2
1
6
Yield: 2.0 g (90%), mp 184-186 °C (decomp). Mass spectrum
was prepared as described previously.
Reaction of (Me Si) Al OEt and PMAB. A sample of
PMAB (0.52 g, 3.1 mmol) in hexane (15 mL) was combined
while stirring with (Me Si) Al OEt (1.0 g, 3.1 mmol) in hexane
20 mL) at -78 °C. After 4 h at -78 °C, the mixture was warmed
23 °C) and stirred (15 h). Volatiles were removed by vacuum
Si) Al PMAB (1). Yield:
.1 g (89%). The solid was recrystallized from hexane providing
+
(
EI, 30 eV, m/z): 428 (M-CH
3
). Infrared spectrum (KBr,
cm ): 3273 (w), 3027 (w), 2938 (m), 2922 (m), 2826 (w), 1481
vs), 1456 (vs), 1389 (br, vs), 1339 (s), 1298 (m), 1219 (s), 1198 (s),
3
3
3
2
-1
(
3
3
3
2
1
6
6
101 (s), 1034 (m), 1009 (vw), 882 (m), 866 (s), 772 (m), 702 (s),
(
(
1
85 (s), 586 (m). Cis isomer: H NMR (C
6 6
D ): δ -0.33 (s, AlMe,
H), -0.24 (s, AlMe, 6H), 0.41 (s, B-4,6 Me, 12H), 2.69 (s, N-5
evaporation leaving a white solid, (Me
3
3
13
1
3
Me, 6H), 2.90 (s, N-1,3 Me, 12H). C{ H} (C D ): δ -5.28
6
6
1
(AlMe), 0.11 (B-4,6 Me), 34.55 (N-5 Me), 34.61 (N-1,3 Me).
Trans isomer: H NMR (C
B-4,6 Me, 12H), 2.68 (s, N-5 Me, 6H), 2.87 (s, N-1,3 Me, 12H)
colorless single crystals: mp 95-97 °C (decomp). Mass spectrum
1
þ
-1
6 6
D ): δ -0.28 (s, AlMe, 12H), 0.41 (s,
(
(
EI, 30 eV, m/z): 412 (M ). Infrared spectrum (KBr, cm ): 3360
w), 3308 (w), 2942 (s), 2890 (s), 2832 (m), 1609 (m), 1559 (m),
11
1
Cis/Trans 1/1.6. B{ H} NMR (C D ): δ 28.7 (B2), 37.2 (B4,6).
6
6
1
1
474 (vs), 1449 (vs), 1404 (br, vs), 1281 (m), 1246 (s), 1109 (s),
051 (m), 1028 (m), 963 (s), 835 (vs), 762 (w), 719 (w), 611 (m).
Anal. Calcd for C14
Found: 37.77; H, 9.81; N, 23.98.
3
Reaction of Et Al with PMAB. A sample of Et Al (4 mL, 1.90
44 6 8 2
H B N Al : C, 37.93; H, 10.00; N, 25.27.
1
H NMR (C D ): δ 0.28 (s, SiMe, 27H), 0.39 (s, B-4,6 Me, 6H),
6
6
3
1
.89 (s, NH
2
, 2H), 2.53 (s, N-1,3 Me, 6H), 2.62 (s, N-5 Me, 3H).
C{ H} NMR (C ): δ - 0.02 (B-4,6 Me), 2.88 (SiMe), 32.60
N-1,3 Me), 34.68 (N-5 Me). B{ H} NMR (C D ): δ 27.29
1
3
1
M in toluene, 7.6 mmol) was added with stirring to PMAB (1.3 g,
7.6 mmol) in toluene (30 mL) at 23 °C. The mixture was stirred
6 6
D
1
1
1
(
(
6
6
(
20 h) and then refluxed (2 h). Ethane was detected in the off-gas
B-2), 37.59 (B 4,6). Anal. Calcd for C H AlB N Si : C, 40.79;
1
1
34
3
4
3
by IR and solvent was removed by vacuum evaporation. The
resulting white residue was recrystallized from hexane forming
colorless crystals of [Et AlN(H)Me B N Me ] (5). Yield: 1.3 g
2 2 3 3 3 2
H, 10.76; N, 13.59. Found: C, 40.57; H, 10.65; N, 13.04.
Decomposition of (Me Si) Al PMAB. sample of
Me Si) Al OEt (1.0 g, 3.1 mmol) in hexane (20 mL) was added
to a solution of PMAB (0.52 g, 3.1 mmol) in hexane (20 mL) at
3
3
3
A
(
3
3
2
3
(
(
(
(
71%), mp 171-173 °C. Mass spectrum (EI, 30 eV, m/z): 499
þ
-1
M ). Infrared spectrum (KBr, cm ): 3268 (m), 2938 (s), 2903
s), 2863 (s), 1603 (m), 1479 (vs), 1456 (vs), 1398 (br, vs), 1292
m), 1215 (s), 1101 (s), 1034 (m), 984 (m), 953 (m), 882 (s), 856 (s),
-
78 °C. The mixture was warmed to 23 °C and stirred (12 h).
The volatiles were vacuum evaporated, the residue (1) redis-
solved in toluene (30 mL), and the solution refluxed (24 h).
Volatiles were vacuum evaporated, and the solid residue washed
1
7
70 (m), 696 (s), 665 (s), 619 (s), 557 (m), 536 (m). Cis isomer. H
NMR (C D ): δ 0.41-0.56 (s, br, AlCH , 8H), 1.13-1.37 (s, br,
with hexane (2 ꢀ 10 mL) leaving a white solid [(Me
3
Si)
2
-
AlN(H)Me Me (2). Yield: 0.90 g, 85%. The solid was
6
6
2
AlCH
2
2
3
CH , 12H), 0.43 (s, B-4,6 Me, 12H), 2.67 (s, N-5 Me, 6H),
2
B
N
3 3
3 2
]
1
3
1
6 6
.92 (s, N-1,3 Me, 12H). C{ H} (C D ): δ 0.16 (B-4,6 Me), 3.09
recrystallized from hot hexane providing colorless single crys-
tals: mp 190-192 °C (decomp.). Mass spectrum (EI, 30 eV, m/z):
(
AlCH ), 8.65 (AlCH CH ), 9.52 (AlCH CH ), 34.41 (N-5 Me),
2
2
3
2
3
1
þ
-1
3
AlCH
4.54 (N-1,3 Me). Trans isomer. H (C
, 8H), 1.13-1.37 (s, br, AlCH
6
D
6
): δ 0.25-0.41 (s, br,
6
(
(
61 (M - Me ). Infrared spectrum (KBr, cm ): 3264 (w), 2949
2
2
CH
3
, 12H), 0.43 (s, B-4,6
Me, 12H), 2.68 (s, N-5 Me, 6H), 2.96 (s, N-1, 3 Me, 12H).
m), 2893 (s), 2834 (m), 1605 (w), 1456 (br, s), 1404 (br, s), 1283
m), 1250 (s), 1198 (m), 1103 (s), 1036 (m), 882 (m), 837 (vs), 764
1
13
1
(
m), 677 (m). Cis isomer: H NMR (C D ): δ 0.20 (s, SiMe,
C{ H} (C
(AlCH CH ), 34.41 (N-5 Me), 34.54 (N-1,3 Me) Cis/Trans 1/
1.1. B{ H} (C ): δ 29.3 (B2), 37.5 (B4,6). Anal. Calcd.
: C, 43.28; H, 10.49; N, 22.43. Found: C,
6 6 2
D ): δ 0.16 (B-4,6 Me), 3.71 (AlCH ), 9.04
6
6
1
8H), 0.33 (s, SiMe, 18H), 0.43 (s, B-4,6 Me, 12H), 2.65 (s, N-5
2
3
1
3
1
11
1
Me, 6H), 3.14 (s, N-1,3 Me, 12H), 3.55 (br, NH, 2H). C{ H}
NMR (C D ): δ 1.73 (Me Si), 2.07 (Me Si), 34.46 (N-5 Me),
D
6 6
18 2 6 4
C H52Al B N
6
6
3
3
1
5.63 (N-1, 3 Me). Trans isomer: H NMR (C
3
SiMe, 36H), 0.42 (s, B-4,6 Me, 12H), 2.63 (s, N-5 Me, 6H), 3.15
6
D
6
): δ 0.28 (s,
43.42; H, 11.21; N, 20.43.
Reaction of i-Bu Al with PMAB. A sample of i-Bu Al (10 mL,
3
3
1
s, N-1,3 Me, 12H), 3.63 (br, NH, 2H). C{ H} (C
3
1
(
(
6
D
6
): δ 1.82
1.0 M in toluene, 10 mmol) was added to a solution of PMAB
(1.7 g, 10 mmol) in toluene (20 mL) at 23 °C, which was stirred
(23 °C, 2 h) and then refluxed (4 h). Volatiles were removed by
vacuum evaporation, and the white residue was recrystallized
from hexane leaving single crystals of [i-Bu AlN(H)Me -
Me Si), 34.48 (N-5 Me), 35.75 (N-1,3 Me). Cis/Trans 1/2.8.
3
1
1
1
B{ H} NMR (C
Si
8.64; H, 11.11; N, 15.39. Trap to trap vacuum separation of
6
D
6
): δ 26.1 (B2), 36.1 (B4,6). Anal. Calcd. for
C
3
22
H
68 Al
2
B
N
6 8
4
: C, 39.09; H, 10.14; N, 16.58. Found: C,
2
2
the reaction volatiles led to identification of Me SiH as the byproduct.
3
B N Me ] [Me N B (Me) (NH )] , (6 [Me N B (Me) -
3
3
3
3 2
3
3
3
3
2
2
0.5
3
3
3
2
Formation of [(Me SiAl) (Me SiN) NH] (3). A sample of 2
4
(NH
spectrum (EI, 30 eV, m/z): 555 (M - (CH
spectrum (KBr, cm ): 3273 (w), 2949 (vs), 2863 (s), 2783 (w),
1605 (m), 1454 (br, vs), 1406 (br, vs), 1289 (m), 1250 (m), 1217
(m), 1198 (m), 1101 (s), 1065 (m), 1036 (m), 1013 (w), 880 (m),
2
)]0.5). Yield: 2.0 g (65%), mp 108-110 °C. Mass
3
3
3
þ
(
(
0.4 g, 0.6 mmol) was dissolved in toluene (20 mL) and refluxed
3 d). Volatiles were vacuum evaporated and the white solid
3
)
2
CHCH
2
). Infrared
-
1
residue washed with hexane (3 ꢀ 10 mL) leaving a white solid.
1
H NMR analysis indicated that the majority of the sample
remained as 2; however, several low intensity resonances (δ 0.35,
1
856 (m), 814 (w), 770 (w), 647 (m), 484 (m). Cis isomer. H NMR
): δ 0.30-0.62 (m, AlCH
(
(
C
6
D
6
2
), 0.45 (s, B-4,6 Me), 1.01
, JHH = 6.4 Hz,
d, CH , JHH = 6.5 Hz, 24H), 1.15 (d, CH
3
3
(
15) (a) R o€ sch, L. Angew. Chem., Int. Ed. Engl. 1977, 16, 480. (b) R €o sch, L.;
Altnau, G. J. Organomet. Chem. 1980, 195, 47–53.
16) (a) Narula, C. K.; Lindquist, D. A.; Fan, M.; Borek, T. T.; Duesler,
E. N.; Datye, A. K.; Schaeffer, R.; Paine, R. T. Chem. Mater. 1990, 2, 377–
84. (b) Toeniskoetter, R. H.; Hall, F. R. Inorg. Chem. 1963, 2, 29–36.
2
1
4H), 2.08 (m, CH), 2.66 (s, N-5 Me, 6 H), 3.03 (s, N-1,3 Me,
1
2H). Trans isomer. H NMR (C D ): δ 0.30-0.61 (m, AlCH ),
(
6
6
2
3
0.45 (s, B-4,6 Me), 1.09 (d, CH , JHH = 6.4 Hz, 24H), 2.08
3
(m, CH), 2.65 (s, N-5 Me, 6 H), 3.01 (s, N-1, 3 Me, 12H).