Reactions of AIH3·NME3 with nitriles: Structural characterization and substitution reactions of hexameric aluminum imides

Article abstract of DOI:10.1021/ic011101g

The reaction of AIH₃·NMe₃ with RCN proceeds with the evolution of trimethylamine and affords (HAINCH₂R)₆ (R = Ph (1), p-MeC₆H₄ (2), p-CF₃C₆H₄ (3)). Compounds 1 and 3 are characterized by single-crystal structural analysis. Compound 1 reacts with Me₃SiBr as well as with PhC≡CH to give (XAINCH₂Ph)₆ (X = Br (4), PhC≡C (5)). Structural data and other characterization data of compounds 4 and 5 show that all the hydridic hydrogen atoms in 1 have been replaced by bromine atoms and PhC≡C groups, respectively. Compounds 1-5 are potential precursors for the preparation of aluminum nitride. Crystals of 1 are rhombohedral, space group R3, with a = 15.7457(13) A, b = 15.7457(13) A, c = 14.949(2) A, V = 3209.8(5) A³, and Z = 3. Crystals of 3·3/4C₇H₈ are triclinic, space group P1, with a = 17.527(11) A, b = 18.894(12) A, c = 19.246(15) A, α = 96.11(7)°, β = 102.23(4)°, γ = 106.79(3)°, V= 5867(7) A³, and Z = 4. Compound 4 crystallizes in the monoclinic space group P2₁/c, with a = 14.175(4) A, b = 16.678(5) A, c = 10.731(3) A, β = 106.82(2)°, V = 2428.6(11) A³, and Z = 2. Compound 5·C₇H₈ crystallizes in the monoclinic space group C2/c, with a = 25.842(5) A, b = 15.443(3) A, c= 20.699(4) A, β = 105.88(3)°, V = 7945(3) A³, and Z = 4.

Full text of DOI:10.1021/ic011101g

Inorg. Chem. 2002, 41, 2374−2378
Reactions of AlH ‚NMe3 with Nitriles: Structural Characterization and
3
Substitution Reactions of Hexameric Aluminum Imides†
N. Dastagiri Reddy, Herbert W. Roesky,* Mathias Noltemeyer, and Hans-Georg Schmidt
Institut fu¨r Anorganische Chemie, UniVersita¨t Go¨ttingen, Tammannstrasse 4,
D-37077, Go¨ttingen, Germany
Received October 22, 2001
The reaction of AlH ‚NMe3 with RCN proceeds with the evolution of trimethylamine and affords (HAlNCH R)6 (R )
3
2
Ph (1), p-MeC H (2), p-CF C H (3)). Compounds 1 and 3 are characterized by single-crystal structural analysis.
6
4
3 6 4
Compound 1 reacts with Me3SiBr as well as with PhCtCH to give (XAlNCH Ph)6 (X ) Br (4), PhCtC (5)).
2
Structural data and other characterization data of compounds 4 and 5 show that all the hydridic hydrogen atoms
in 1 have been replaced by bromine atoms and PhCtC groups, respectively. Compounds 1−5 are potential
precursors for the preparation of aluminum nitride. Crystals of 1 are rhombohedral, space group R3h, with a )
3
15.7457(13) Å, b ) 15.7457(13) Å, c ) 14.949(2) Å, V ) 3209.8(5) Å , and Z ) 3. Crystals of 3‚3/4C H are
7
8
triclinic, space group P1h, with a ) 17.527(11) Å, b ) 18.894(12) Å, c ) 19.246(15) Å, R ) 96.11(7)°, â )
3
102.23(4)°, γ ) 106.79(3)°, V ) 5867(7) Å , and Z ) 4. Compound 4 crystallizes in the monoclinic space group
3
P21/c, with a ) 14.175(4) Å, b ) 16.678(5) Å, c ) 10.731(3) Å, â ) 106.82(2)°, V ) 2428.6(11) Å , and Z )
2. Compound 5‚C H crystallizes in the monoclinic space group C2/c, with a ) 25.842(5) Å, b ) 15.443(3) Å, c )
7
8
3
20.699(4) Å, â ) 105.88(3)°, V ) 7945(3) Å , and Z ) 4.
Introduction
organic solvents and containing an equivalent of hydridic
hydrogen per Al atom, was reported but not characterized.
Reactions of alanes and alanates with various amines leading
to aluminum imides and amides have been well-docu-
mented.3,5 There have been reports on the formation of
aluminum imides from reactions 1-34,5c,6 (Scheme 1). A few
crystal structures of aluminum imides (n ) 4, 6, or 8)
Aluminum imides and amides, containing the (AlN)n
skeleton, are potential precursors for the chemical vapor
deposition of aluminum nitride.1 The physical and chemical
properties of aluminum nitride strongly depend on its purity.
Aluminum nitride is one of the best electrical insulators for
microelectronic applications.2 In addition to the utility in
industry the complex structural features of the Al-N systems
make them an interesting class of compounds from an
academic point of view.3 The reaction of methylamine and
alane dates back to 1955.4 An Al-N polymer, insoluble in
(3) (a) Waggoner, K. M.; Hope, H.; Power, P. P. Angew. Chem. 1988,
100, 1765; Angew. Chem., Int. Ed. Engl. 1988, 27, 1699. (b) Waggoner,
K. M.; Power, P. P. J. Am. Chem. Soc. 1991, 113, 3385. (c) Cesari,
M.; Cucinella, S. The Chemistry of Inorganic Homo- and Heterocycles;
Haiduc, I., Sowerby, D. B., Eds.; Academic Press: London. 1987;
Vol I, p 167. (d) Gilbert, J. K.; Smith, J. D. J. Chem. Soc. 1968, 233.
(e) Al-Wassil, A.-A. I.; Hitchcock, P. B.; Sarisaban, S.; Smith, J. D.;
Wilson, C. L. J. Chem. Soc., Dalton. Trans. 1985, 1929, and references
therein. (f) Ruff, J. K.; Hawthorne, F. J. Am. Chem. Soc. 1960, 82,
2141. (g) Wiberg, E.; May, A. Z. Naturforsch. B 1955, 10, 230.
(4) Wiberg, E.; May, A. Z. Naturforsch. B 1955, 10, 232.
† Dedicated to Professor Karl Wieghardt on the occasion of his 60th
birthday.
* Author to whom correspondence should be addressed. E-mail: hroesky@
gwdg.de.
(1) (a) Haussonne, J.-M. Mater. Manuf. Processes 1995, 10, 717. (b)
Interrante, L. V. GoV. Rep. Announce. Index (U. S.) 1995, 95, Abstr.
No. 508,364 (CAS: 1996, 124, 41572). (c) Interrante, L. V. GoV. Rep.
Announce. Index (U. S.) 1993, 93, Abstr. No. 350,504 (CAS: 1994,
121, 89550). (d) Jensen, J. L. U.S. Pat., US 5,276,105.
(2) (a) Boyd, D. C.; Haasch, R. T.; Mantell, P. R.; Schulze, R. K.; Evans,
J. F.; Gladfelter, W. L. Chem. Mater. 1989, 1, 119. (b) Bolt, J. D.;
Tebbe, F. N. AdV. Ceram. 1989, 26, 69. (c) Bertalet, D. C.; Liu, H.;
Rogers, J. W. J. Appl. Phys. 1994, 75, 5385. (d) Jones, A. C. J. Cryst.
Growth 1993, 129, 728. (e) Rockensu¨ss, W.; Roesky, H. W. AdV.
Mater. 1993, 5, 443.
(5) (a) Wehmschulte, R. J.; Power, P. P. Polyhedron 2000, 19, 1649, and
references therein. (b) Wehmschulte, R. J.; Power, P. P. J. Am. Chem.
Soc. 1996, 118, 791. (c) Ehrlich, R.; Young, A. R., II; Lichstein, B.
M.; Perry, D. D. Inorg. Chem. 1964, 3, 628. (d) Montero, M. L.;
Wessel, H.; Roesky, H. W.; Teichert, M.; Uso´n, I. Angew. Chem. 1997,
109, 644; Angew. Chem., Int. Ed. Engl. 1997, 36, 629. (e) Linti, G.;
No¨th, H.; Rahm, P. Z. Naturforsch. B 1988, 43, 53. (f) Heine, A.;
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1992, 31, 854.
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Chem. 1976, 121, 137, and references therein.
2374 Inorganic Chemistry, Vol. 41, No. 9, 2002
10.1021/ic011101g CCC: $22.00 © 2002 American Chemical Society
Published on Web 04/05/2002

Reactions of AlH3‚NMe3 with Nitriles
Scheme 1
Scheme 2
obtained from reactions 1 and 2 have also been reported.
The influence of the nature of the amine on the structure
and extent of oligomerization of these imides has also been
established. Even though the reactions of trialkylamine alanes
with acetonitrile and propionitrile have been reported almost
4 decades ago, to the best of our knowledge so far there is
no structural evidence for the formation of aluminum imides
from reaction 3. Power et al. have reported that the reaction
of a bulky alane [Mes*AlH2]2 (Mes* ) 2,4,6-t-Bu3C6H2)
with nitriles RCN (R ) Me, t-Bu, Mes) gives the ortho-
metalated dimers, cis- and trans-[AlC6H2-2,4-t-Bu2-6-CMe2-
CH2{µ2-N(H)CH2R}]2. However, the formation of an alu-
minum imide [Mes*AlNCH2R]n was not observed.7 Recent
studies by our group on the reaction of AlH3‚NMe3 with
C-C and C-N multiple bond systems have resulted in
structurally interesting, highly stable polyhedral aluminum
clusters.8
In this contribution, we report the synthesis and structural
characterization of reaction products from the treatment of
AlH3‚NMe3 with PhCN, p-MeC6H4CN, and p-CF3C6H4CN.
We also report for the first time on the functionalization
reactions of one of the products, (HAlNCH2Ph)6, with Me3-
SiBr and PhCtCH. These reactions are summarized in
Scheme 2.
room temperature before it was refluxed until the evolution of NMe3
ceased. Reducing the volume to 10 mL and cooling to 0 °C afforded
colorless crystals of 1. These were separated from the mother liquor
by decantation and dried well under vacuum. Yield 0.60 g (46%).
Mp: 245 °C (decomp). NMR (CDCl3): 1H, δ 4.20 (s, 12H, CH2),
7.14 (m, 30H, C6H5); 13C, δ 49.49 (CH2), 126.96 (p-C6H5), 127.52
(m-C6H5), 128.81 (o-C6H5), 142.40 (CH2-C). IR: 1855s, 1494m,
1310w, 1201w, 1031m, 1009s, 903w, 819m, 748s, 730s, 663s,
524m, 481m, 436m cm-1. Anal. Calcd for C42H48Al6N6: C, 63.15;
H, 6.06; Al, 20.27; N, 10.52. Found: C, 62.77; H, 5.99; Al, 19.12;
N, 10.41.
Experimental Section
Reaction of AlH3‚NMe3 with p-MeC6H4CN (Synthesis of 2).
The reaction between AlH3‚NMe3 (25 mL, 0.5 M solution in
toluene) and p-MeC6H4CN (1.00 g, 8.5 mmol) was carried out in
the same way as the reaction between AlH3‚NMe3 and PhCN.
Yield: 0.82 g (65%). Mp: 233 °C (decomp). NMR (CDCl3): 1H,
δ 2.39 (s, 18H, CH3), 4.15 (s, 12H, CH2), 6.89 (m, 12H, m-C6H4),
7.23 (m, 12H, o-C6H4).13C, δ 21.23 (CH3), 49.10 (CH2), 125.30
(p-C6H4), 127.53 (m-C6H4), 129.42 (o-C6H4), 139.60 (CH2-C). IR:
1887w, 1855s, 1515w, 1316w, 1261w, 1202w, 1183w, 1004m,
General Procedures. All experimental manipulations were
carried out under an atmosphere of dry nitrogen using standard
Schlenk techniques. The samples for spectral measurements were
prepared in a drybox. Solvents were purified according to conven-
tional procedures and were freshly distilled prior to use. AlH3‚NMe3
was prepared as described in the literature.9 PhCN (Aldrich) was
distilled over P4O10. p-CF3C6H4CN, p-MeC6H4CN, Me3SiBr, and
PhCtCH were procured from Aldrich and used as such. NMR
spectra were recorded on a Bruker AM 200 or a Bruker AS 400
instrument, and the chemical shifts are reported with reference to
tetramethylsilane (TMS). IR spectra were recorded on a Bio-Rad
Digilab FTS7 spectrometer. Melting points were obtained on a
HWS-SG 3000 apparatus and are uncorrected. CHN analyses were
performed at the Analytical Laboratory of the Institute of Inorganic
Chemistry at Go¨ttingen, Germany.
985m, 935w, 842w, 808m, 758s, 730s, 672s, 505m, 470w cm-1
.
Anal. Calcd for (2‚C7H8) C55H68Al6N6: C, 67.75; H, 7.03; N, 8.62.
Found: C, 67.40; H, 6.37; N, 8.58.
Reaction of AlH3‚NMe3 with p-CF3C6H4CN (Synthesis of 3).
The reaction between AlH3‚NMe3 (20 mL, 0.5 M solution in
toluene) and p-CF3C6H4CN (0.85 g, 5.0 mmol) was carried out in
the same way as the reaction between AlH3‚NMe3 and PhCN.
Yield: 0.63 g (63%). Mp: 240 °C (decomp). NMR (CDCl3): 1H,
δ 4.25 (s, 12H, CH2), 7.21 (m, 24H, C6H4).13C, δ 49.18 (CH2),
123.83 (m, CF3, JC-F ) 272 Hz) 126.89 (m-C6H4) 127.96 (o-C6H4),
130.34 (m, p-C6H4, JC-F ) 33 Hz), 145.61 (CH2-C). IR: 1877s,
1618w, 1419w, 1326s, 1262w, 1168m, 1131s, 1068s, 1033w, 982w,
860w, 820m, 740s, 693m, 632w, 550w, 499w, 445w cm-1. Anal.
Calcd for (3‚3/4C7H8) C53.25H48Al6F18N6: C, 50.13; H, 3.79; F,
26.80; N, 6.59. Found: C, 50.62; H, 3.94; F, 26.43; N, 6.51.
Reaction of 1 with Me3SiBr (Synthesis of 4). To a suspension
of 1 (0.30 g, 0.4 mmol) in toluene (20 mL) was added Me3SiBr
(0.40 g, 2.6 mmol) at room temperature. The reaction mixture was
Reaction of AlH3‚NMe3 with PhCN (Synthesis of 1). AlH3‚
NMe3 (30 mL, 0.5 M solution in toluene) was added to a solution
of PhCN (1.00 g, 9.7 mmol) in toluene (15 mL) at -78 °C. The
mixture was stirred at this temperature for an hour and brought to
(7) Wehmschulte, R. J.; Power, P. P. Inorg. Chem. 1998, 37, 6906.
(8) (a) Zheng, W.; Stasch, A.; Prust, J.; Roesky, H. W.; Cimpoesu, F.;
Noltemeyer, M.; Schmidt, H.-G. Angew. Chem. 2001, 113, 3569;
Angew. Chem., Int. Ed. Engl. 2001, 40, 3461. (b) Stasch, A.;
Ferbinteanu, M.; Prust, J.; Zheng, W.; Cimpoesu, F.; Roesky, H. W.;
Magull, J.; Schmidt, H.-G.; Noltemeyer, M. J. Am. Chem. Soc.,
accepted for publication.
(9) Ruff, J. K.; Hawthorne, M. F. J. Am. Chem. Soc. 1960, 82, 2141.
Inorganic Chemistry, Vol. 41, No. 9, 2002 2375

Reddy et al.
stirred overnight and refluxed for an hour. The solution was filtered
after cooling to room temperature and stored at 0 °C overnight to
obtain colorless crystals of (PhCH2NAlBr)6, 4. The crystals were
dried under vacuum after decanting the mother liquor. Yield: 0.40
g, (83%). Mp: 296 °C (decomp). IR: 1560w, 1307w, 1262w,
1203w, 1030w, 977m, 962m, 817m, 741s, 722s, 691m, 660m,
549w, 512w cm-1. Anal. Calcd for C42H42Al6Br6N6: C, 39.65; H,
3.33; N, 6.61. Found: C, 39.43; H, 3.61; N, 6.37.
evolution of hydrogen. All the hydridic hydrogen atoms were
substituted by the acetylide moieties forming compound 5.
Compound 5 is extremely air-/moisture-sensitive, and hence
our attempts to obtain a proper analytical data were unsuc-
cessful. The results were inconsistent.
The IR spectra of compounds 1-3 exhibit a strong band
around 1860 cm-1 due to ν(Al-H).13 The absence of this
band in 4 and 5 proves that all Al-H bonds are substituted.
A sharp band of medium intensity at 2127 cm-1 in the IR
spectrum of 5 can be attributed to ν(CtC).14 The base peak
in the EI mass spectra of compounds 1-5 corresponds to
the organic substituent on the nitrogen. In addition to EI
spectra, FAB, ES, and FD techniques were also applied on
compounds 1-5. However, no molecular ion peak is
observed.
Reaction of 1 with PhCtCH (Synthesis of 5). The reaction
between 1 (0.42 g, 0.5 mmol) and PhCtCH (0.33 g, 3.2 mmol)
was carried out in the same way as the reaction between 1 and
Me3SiBr. The amount of filtrate was reduced to 10 mL and stored
at 0 °C. Colorless crystals of (PhCH2NAlCtCPh)6, 5, were obtained
after a week. Yield: 0.52 g (70%). Mp: 293 °C (decomp). NMR
(C6D6): 1H, δ 4.83 (s, 12H, CH2), 6.96 (m, 30H, CH2C6H5), 7.37
(m, 18H, p- and m-C6H5CtC), 7.74 (m, 12H, o-C6H5CtC); 13C,
δ 47.25 (CH2), 77.78 (Al-C), 83.87 (Al-CtC), 122.79, 125.64,
127.80, 128.41, 124.48, 128.76, 132.4 (CtCC6H5 and CH2C6H5).
IR: 2127m, 1951w, 1882w, 1804w, 1595m, 1496m, 1262m,
1212m, 1070m, 1026s, 914w, 800s, 755s, 690s, 647s, 611s, 537m
The mechanism of the reaction between PhCN and AlH3‚
NMe3 is not fully understood at present. However, IR and
NMR spectral analyses of an initial product of the reaction
show the involvement of the imide, PhCHdN-AlH2‚NMe3
as an intermediate. A pale yellow colored product was
obtained by the addition of 1.5 equiv of AlH3‚NMe3 in
toluene to a solution of PhCN (in toluene) at room temper-
ature followed by evaporation of all volatiles under high
vacuum. The IR spectrum of the product shows two
absorptions, one in the ν(CdN) region (1653 cm-1) and
another in the ν(Al-H) region (1791 cm-1) in addition to
the absorptions of 1. No absorptions related to ν(CtN) are
cm-1
.
X-ray Structure Determination of 1 and 3-5. A suitable
crystal of each compound was mounted on a glass fiber and coated
with paraffin oil. Diffraction data for 1, 3, and 4 were collected on
a Siemens-Stoe AED2 four-circle instrument (at 200 K for 1 and
3, and at 203 K for 4; data for 5 were collected on a Bruker AXS
CCD diffractometer at 133 K). All measurements were made with
graphite-monochromated MoKR radiation (λ ) 0.710 73 Å). The
structures were solved by direct methods using SHELXS-9710 and
refined against F2 on all data by full-matrix least squares with
SHELXL-97.11 All non-hydrogen atoms were refined aniso-
tropically. Neutral-atom scattering factors (including anomalous
scattering) were taken from ref 12. Hydrogen atoms were included
at geometrically calculated positions and refined using a riding
model.
1
observed. The H NMR spectrum at 30 °C in toluene-d8
shows three doublet resonances in the phenyl region in
addition to the multiplet related to 1. In agreement with the
unsaturated nature of the intermediate the doublets appear
in the more deshielded region (δ 7.31, 7.41, and 7.65 in a
2:2:1 ratio) compared to the multiplet of 1 (δ 7.14). Upon
heating the sample to 90 °C the doublets distinctively
diminish as the multiplet related to 1 becomes more
prominent. These observations are in accordance with the
proposed intermediate, PhCHdN-AlH2‚NMe3, which can
be expected to form by the transfer of a hydride to the nitrilic
carbon atom. Upon heating PhCHdN-AlH2‚NMe3 the
elimination of NMe3 and the formation of 1 are observed.
Crystallographic data for the structural analyses of com-
pounds 1 and 3-5 are given in Table 1, and the important
bond parameters are listed in Table 2. The molecular
structure of 1 is shown in Figure 1. Compound 1 crystallizes
in the rhombohedral space group R3h with one-sixth of the
molecule in the asymmetric unit. Compound 1 basically
contains an hexagonal drum with the top and bottom faces
of the polyhedron being made of two six-membered (AlN)3
rings, which are almost planar. These six-membered rings
are joined by six transverse Al-N bonds forming six
rectangular side faces of the drum. As with the previously
studied structures, the Al-N bonds in the six-membered rings
are significantly shorter than the transverse bonds joining
Results and Discussion
The major objective of the work described here was the
structural characterization of the products of a reaction
between RCN and AlH3‚NMe3 and their stability toward
nucleophilic reagents. Addition of AlH3‚NMe3 to PhCN in
toluene at -78 °C resulted in a yellow colored solution,
which turned colorless upon refluxing. Keeping the solution
at 0 °C overnight yielded colorless crystals of 1. In a similar
way, p-MeC6H4CN and p-CF3C6H4CN react with AlH3‚NMe3
and give 2 and 3. Compounds 1-3 are air-/moisture-sensitive
and decompose at 245, 233, and 240 °C, respectively, with
the evolution of a gas. Compound 1 smoothly reacts with
an excess of Me3SiBr in toluene, and all the hydridic
hydrogen atoms are replaced by bromine atoms. Compound
4 is the sole product of the reaction. However, a complex
mixture of products (based on 19F NMR) was formed when
Me3SnF was employed in place of Me3SiBr. The reaction of
compound 1 with PhCtCH, which reacts with AlH3‚NMe3
and forms an Al-C network,8b is straightforward with the
(10) Sheldrick, G. M. SHELXS-90/96, Program for Structure Solution. Acta
Crystallgr., Sect. A 1990, 46, 467.
(11) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(12) International Tables for X-ray Crystallography; Kynoch Press:
Birmingham, England, 1969; Vol. IV, pp 55, 99, 149.
(13) (a) Gardiner, M. G.; Koutsantonis, G. A.; Lawrence, S. M.; Lee, F.-
C.; Raston, C. L. Chem Ber. 1996, 129, 545. (b) Jones, C.; Lee, F.-
C.; Koutsantonis, G. A.; Gardiner, M. G.; Raston, C. L. J. Chem. Soc.,
Dalton Trans. 1996, 829.
(14) Szymanski, H. A. Interpreted Infrared Spectra; Plenum Press Data
Division: New York. 1966; Vol 2, p 5.
2376 Inorganic Chemistry, Vol. 41, No. 9, 2002

Reactions of AlH3‚NMe3 with Nitriles
Table 1. Crystallographic Data for the Structural Analyses of 1, 3‚3/4C7H8, 4, and 5‚C7H8
1
3‚3/4C7H8
4
5‚C7H8
empirical formula
fw
T/K
λ/Å
cryst syst
space group
a/Å
b/Å
c/Å
R/deg
â/deg
γ/deg
V/Å3
Z
C42H48Al6N6
798.74
200(2)
0.710 73
rhombohedral
R3h
15.7457(13)
15.7457(13)
14.949(2)
90
90
120
3209.8(5)
3
1.240
C53.25H48Al6F18N6
1275.86
200(2)
0.710 73
triclinic
P1h
17.527(11)
18.894(12)
19.246(15)
96.11(7)
102.23(4)
106.79(3)
5867(7)
C42H42Al6Br6N6
1272.16
203(2)
0.710 73
monoclinic
P21/c
14.175(4)
16.678(5)
10.731(3)
90
106.82(2)
90
2428.6(11)
2
1.740
5.106
1248
C97H80Al6N6
1491.55
133(2)
0.710 73
monoclinic
C2/c
25.842(5)
15.443(3)
20.699(4)
90
105.88(3)
90
7945(3)
4
1.247
0.134
3128
4
D(calcd)/(g‚cm-3
µ(Mo KR)/cm-1
F(000)
)
1.444
0.209
2598
1.00 × 0.60 × 0.30
3.51-22.20
-18 e h e 18
-19 e k e 19
-19 e l e 20
17 020
0.187
1260
cryst size/mm3
θ range/deg
0.80 × 0.70 × 0.70
0.50 × 0.40 × 0.30
3.73-25.02
-16 e h e 16
-19 e k e 12
-12 e l e 12
7655
1.00 × 0.80 × 0.60
2.38-27.73
-33 e h e 32
0 e k e 20
0 e l e 27
8878
4.18-24.97
index range
-17 e h e 17
-12 e k e 12
-17 e l e 17
2020
reflns collected
independent reflns
refinement method
data/restraints/params
R1, R2 (I > 2σ(I))a
R1, R2 (all data)a
S
848
14 183
4265
8878
full-matrix least-squares on F2
848/0/86
14183/1044/1497
0.1125, 0.3108
0.1637, 0.3831
1.429
4265/0/271
0.0528, 0.1197
0.0839, 0.1380
1.033
8878/501/508
0.0896, 0.1964
0.0978, 0.2019
1.213
0.0334, 0.0861
0.0365, 0.0890
1.120
∆F(min), ∆F(max)/(e‚Å3)
0.150, -0.190
1.760, -0.706
0.890, -0.888
0.891, -0.819
2
2
2 2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. R2 ) [∑w(|Fo | - |Fc |)2/∑w|Fo | ]1/2
.
Table 2. Selected Bond Lengths and Bond Angles of Compounds 1
and 3-5
bond distances (Å)
bond angles (deg)
Compound 1
Al(1a)-N(1)-Al(1b) 124.37(8)
N(1a)-Al(1)
1.886(2)
Al(1)-N(1b) 1.893(2)
N(1)-Al(1)-Al(1b)
N(1a)-Al(1)-N(1)
N(1a)-Al(1)-N(1b)
Al(1a)-N(1)-Al(1)
N(1)-Al(1)-N(1b)
88.77(6)
91.26(6)
115.25 (8)
88.57(6)
91.05(6)
Al(1)-N(1)
1.9736(14)
Compound 3
Al(1)-N(1)
Al(1)-N(3)
Al(1)-N(2)
Al(2)-N(2)
Al(3)-N(3)
1.880(10)
1.902(11)
1.980(10)
1.900(10)
1.959(10)
N(1)-Al(1)-N(3)
N(3)-Al(1)-N(2)
Al(3)-N(2)-Al(1)
N(1)-Al(1)-N(2)
Al(3)-N(2)-Al(2)
Al(2)-N(2)-Al(1)
115.3(5)
90.8(4)
88.4(4)
91.1(4)
124.0(5)
88.1(4)
Compound 4
Al(1)-N(1)
Al(1)-N(2)
Al(1)-Br(1)
Al(2)-N(3)
Al(2)-N(1)
1.889(5)
1.972(6)
2.245(2)
1.873(5)
1.982(6)
N(1)-Al(1)-N(2)
N(1)-Al(1)-Br(1)
Al(3)-N(1)-Al(1)
N(3)-Al(2)-N(2)
N(2)-Al(1)-Br(1)
91.9(2)
120.2(2)
123.5(3)
116.4(2)
113.9(2)
Figure 1. Crystal structure of compound 1. All hydrogen atoms except
those on Al are excluded for clarity.
the rings.3e,15 The benzyl groups are oriented toward each
other, blocking the top and bottom faces of the hexagonal
drum and thereby exposing the hydridic hydrogens. This can
be seen in the reactivity of compound 1 with nucleophiles
such as Me3SiBr and PhCtCH.
Compound 3 crystallizes in the triclinic space group P1h
with two halves of the molecule and another independent
molecule along with 1.5 molecules of toluene in the
asymmetric unit. The molecular structure of 3 is shown in
Figure 2. Bond parameters and other features of the molecule
are similar to those of compound 1. A plot of 4 is given in
Compound 5
Al(1)-N(3)
Al(1)-N(1)
Al(1)-C(11)
Al(1)-N(2)
C(11)-C(12) 1.196(5)
C(12)-C(13) 1.444(5)
1.876(3)
1.884(3)
1.912(4)
1.972(3)
N(3)-Al(1)-N(1)
N(1)-Al(1)-C(11)
Al(1)-N(1)-Al(2)
C(11)-C(12)-C(13)
C(22)-C(21)-Al(2)
C(32)-C(31)-Al(3)
N(3)-Al(1)-C(11)
N(3)-Al(1)-N(2)
Al(2)-N(2)-Al(3)
C(12)-C(11)-Al(1)
C(21)-C(22)-C(23)
C(31)-C(32)-C(33)
114.33(13)
120.24(15)
88.34(12)
178.7(4)
178.3(3)
171.2(3)
116.65(15)
91.66(12)
122.12(16)
174.6(3)
178.6(4)
176.7(4)
Figure 3. Compound 4 crystallizes in the monoclinic space
group P21/c with half of the molecule in the asymmetric unit.
(15) Cesari, M.; Perego, G.; Del Piero, G.; Cucinella, S.; Cernia, E. J.
Organomet. Chem. 1974, 78, 203.
Inorganic Chemistry, Vol. 41, No. 9, 2002 2377

Reddy et al.
Figure 4. Crystal structure of compound 5. All hydrogen atoms are
excluded for clarity.
180° and vary significantly from each other (C(12)-C(11)-
Al(1) ) 174.6(3)°, C(22)-C(21)-Al(2) ) 178.3(3)°, and
C(32)-C(31)-Al(3) ) 171.2(3)°). In a similar way, CtC-C
bond angles also deviate slightly from linearity (C(11)-
C(12)-C(13) ) 178.7(4)°, C(21)-C(22)-C(23) ) 178.6(4)°,
and C(31)-C(32)-C(33) ) 176.7(4)°).
Figure 2. Crystal structure of compound 3. All hydrogen atoms except
those on Al are excluded for clarity.
Conclusion
The products of general formula (HAlNCH2R)6 resulting
from the reaction between nitriles and AlH3‚NMe3 have been
structurally characterized. It has been shown that they
basically contain an hexagonal drum made of an (AlN)6
network and a hydridic hydrogen per Al atom. The stability
of one of these (AlN)6 clusters toward nucleophilic reagents
such as PhCtCH and Me3SiBr has been demonstrated.
Presently we are investigating the preparation of aluminum
nitride from compounds 1 and 2.
Figure 3. Crystal structure of compound 4. All hydrogen atoms are
excluded for clarity.
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft and the Go¨ttinger Akad-
emie der Wissenschaften. N.D.R. thanks the Alexander von
Humboldt-Stiftung for a research fellowship.
A comparison of bond distances and bond angles with those
of 1 shows that the cage structure is not disturbed by the
replacement of the hydrogen atoms by the bulky bromine
atoms. A plot of compound 5 is given in Figure 4. Compound
5 crystallizes in the monoclinic space group C2/c with half
of the molecule along with half of a molecule of toluene in
the asymmetric unit. An interesting feature of the structure
is that the CtC-Al bond angles deviate from the expected
Supporting Information Available: Single-crystal X-ray struc-
tural data of compounds 1 and 3-5 (CIF format). This material is
available free of charge via the Internet at http://pubs.acs.org.
IC011101G
2378 Inorganic Chemistry, Vol. 41, No. 9, 2002