A comparative study of the behaviour of N-trimethylsilyl and N-neopentyl-anilines and 1,2-diaminobenzenes towards trimethylalane; X-ray structures of nine Al-N compounds

Article abstract of DOI:10.1039/b300957m

The reactions of a pair each of monosubstituted anilines PhNHR¹ and disubstituted 1,2-diaminobenzenes C6H4(NH^R1)2-1,2 (R¹ = SiMe3 = R, or R¹ = CH2Bu^t = R') with 1 or 2 equivalents of trimethylalane ha

Full text of DOI:10.1039/b300957m

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A comparative study of the behaviour of N-trimethylsilyl and
N-neopentyl-anilines and 1,2-diaminobenzenes towards
trimethylalane; X-ray structures of nine Al–N compounds
Jean-Philippe Bezombes, Barbara Gehrhus, Peter B. Hitchcock, Michael F. Lappert* and
Philippe G. Merle
The Chemistry Laboratory, University of Sussex, Brighton, UK BN1 9QJ.
E-mail: m.f.lappert@sussex.ac.uk
Received 23rd January 2003, Accepted 20th March 2003
First published as an Advance Article on the web 2nd April 2003
The reactions of a pair each of monosubstituted anilines PhNHR1 and disubstituted 1,2-diaminobenzenes
C6H4(NHR1)2-1,2 (R1 = SiMe3 = R, or R1 = CH2But = RЈ) with 1 or 2 equivalents of trimethylalane have been
investigated. The trimethylsilyl derivatives were more reactive than the neopentyl analogues. The following crystalline
compounds were obtained at ambient temperature or (1) gentle heating: trans-[AlMe2(µ-NRPh)]2 1, [AlMe3-
{NH(RЈ)Ph}] 2, [(AlMe2)2{µ-(NR)2C6H4-1,2}] 4, [(AlMe2){µ-(NRЈ)2C6H4-1,2}] 5, [(AlMe){N(R)C6H4NR-µ-1,2}]2 6
and [AlMe2{N(RЈ(C6H4N(H)RЈ}] 7, while prolonged heating was required in order to obtain [AlMe2(µ-NRЈPh)]2 3
and [(AlMe{N(RЈ)C6H4NRЈ-µ-1,2}]2 8. The amine adducts 2 and 7, were identified as intermediates to 3 and 8,
respectively. Treatment of C6H4(NHRЈ)2-1,2 with successively 2 LiBun and 2 AlCl3 afforded [AlCl{N(RЈ)C6H4NRЈ-
µ-1,2}]2 9. The diamine adduct [C6H4{N(H)RЈ(AlMe3)}2-1,3] 10 was obtained from C6H4(NHRЈ)2-1,3 and 2 AlMe3;
while the same diamine with successively 2 LiBun, 2 AlClMe2 and 2 tmen yielded a compound tentatively formulated
as [C6H4{N(RЈ)AlMe2(tmen)}2-1,3] 11. The X-ray structures of 1–7, 9 and 10 are presented.
polymerisation of ethylene.18 We recently reported on the syn-
Introduction
thesis and structures of neutral and cationic aluminium 1-aza-
We have a long standing interest in the chemistry of metal and
allyls,19 β-diketiminates,20 and on an amidinate21a (see also ref.
metalloid amides.1 Our most recent publications in this area
21b).
relate to complexes of the N-mono-substituted anilides
ϪN(R1)Ph (A: R1 = SiMe3 = R, or AЈ: R1 = CH2But = RЈ) and
Results and discussion
the N,NЈ-disubstituted 1,2-, 1,3- and 1,4-benzenediamides
{ϪN(R1)}2C6H4 B (R1 = R), BЈ (R1 = RЈ), C (R1 = R) and CЈ
(R1 = RЈ) and D, including the X-ray-characterised complexes
[Li(A)]4,2 [Li{µ-A-trans}(µ-tmen)]∞,3 [Li(µ-AЈ)(OEt2)]2,3 [Li2-
(µ-B)(thf )2{µ-Li(thf )}2]2,4 [{Li(tmen)}2(µ-B)],4 [Li(thf )(µ-B)-
Li(thf )2],4 [{Li(tmen)}2(µ-BЈ)],4 [Li(µ-BЈ)(thf )2(µ-Li)]2,4 [{Li-
(thf )}2(µ-C)],5 [Mg(µ-B)(OEt2)]2,6 [{Zr(B)(NMe2)(µ-NMe2)}2],7
[Zr(B)Cl2(tmen)],7 [Sn(B)(tmen)],8 [Sn(BЈ)]2,8 [{Zr(NMe2)3}2-
(µ-C)],9 [{Zr(NMe2)2}2(µ-C)2],9 [Sn(C)]2,10 [Sn3(C)2],10 [{Zr-
An objective of the present work was to prepare and character-
ise a range of Al–N compounds derived from the amines
HN(Ph)R1 and the diamines 1,2- and 1,3-C6H4[N(R1)H]2
(R1 = SiMe3 = R, or R1 = CH2But = RЈ). As a corollary, it was
anticipated that some generalisations might emerge regarding
the relative reactivities of the trimethylsilyl versus neopentyl
derivatives.
The syntheses in good yields of the crystalline compounds
1–3 based on the anilines HA (1) or HAЈ (2,3) are summarised
in Scheme 1. Whereas equivalent portions of trimethylalane
and N-trimethylsilyl-22 or N-neopentyl3-aniline under mild
conditions (gentle heating for HA, or ambient temperature
for HAЈ) yielded the crystalline dimeric trans-N-trimethylsilyl-
anilinodi(methyl)alane 1 (see also ref. 23, in which a 23% yield
was recorded and the much lower mp of 77–80 ЊC) from HA
(i in Scheme 1), with HAЈ the product was the 1 : 1-adduct 2
(NMe2)3}2(µ-D)],9
[{Zr(NMe2)2}2(µ-D)2],9
[{Ge(NR2)2}2-
(µ-D)],11 [{Sn(NR2)2}2(µ-D)],11 [{Sn(OC6H2But2-2,6-Me-4)}2-
(µ-D)],11 and [{SnCl2(NR2)}2(µ-D)].11 The ligand BЈ has had a
central role in the development of the chemistry of the first
X-ray-characterised silylene Si(BЈ);12a,b for a review of some of
its chemistry, see ref. 12c. The ligands B and BЈ have also
featured in the following compounds: [Ga(B)]2,13 [Ge(B)],14
[MCln(B){η5-C5H3(SiMe3)2-1,3}] (n = 1 and M = Zr or Hf; or
n = 2 and M = Ta),15 [{Mo(B)(NPh)(µ-NPh)}2]16 and various
complexes containing the W(B)(NPh) moiety.17
In this paper, we focus on the amides A and AЈ and the
diamides B, BЈ and CЈ of aluminium and on some amine–alane
adducts. Amides of aluminium have long been studied,1 but
recent interest in Al–N chemistry has been regenerated in part
by the disclosure of Coles and Jordan in 1997 that certain
cationic amidinatoaluminium methyls are catalysts for the
Scheme 1 Synthesis of the crystalline compounds 1–3. Reagents and
conditions: i, AlMe3, n-C6H14, 0 ЊC and then <60 ЊC in vacuo; ii, AlMe3,
n-C6H14, 20 ЊC; iii, n-C6H14, reflux, 16 h.
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
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Scheme 2 Synthesis of the crystalline compounds 4–8. Reagents and conditions: i, 4 AlMe3, n-C6H14, 20 ЊC; ii, 2 AlMe3, n-C6H14, 20 ЊC; iii, PhMe,
100 ЊC, 2 d; iv, 4 LiBun, PhMe, 20 ЊC, then 2 AlCl3 at Ϫ78 to 20 ЊC, 16 h.
(ii in Scheme 1). Prolonged heating of 2 was required in order to
complete the methane-elimination reaction leading (iii in
Scheme 1) to the dimeric cis-N-neopentylanilinodi(methyl)-
alane 3, an analogue of 1 but of opposite stereochemistry.
The syntheses in good (4–8) or moderate (9) yields of the
crystalline compounds 4–9 derived from the 1,2-diamino-
benzenes H2B (4 and 6) and H2BЈ (5 and 7–9) are outlined in
Scheme 2. Treatment of the appropriate diamine and two equiv-
alents of trimethylalane yielded (i in Scheme 2) the dinuclear
chelated diaminobis(dimethylalane)s 4 and 5. By contrast, with
one equivalent of AlMe3, likewise at ambient temperature,
the outcome (ii in Scheme 2) for the two diamines was different,
the product being the bis(amido) compound 6 from H2B but the
amido(amine) compound 7 from H2BЈ. However, thermolysis
of 7 yielded (iii in Scheme 2) the neopentyl analogue 8 of 6. The
dimeric chloro compound 9, related to the dimeric methyl
compound 8, was obtained (iv in Scheme 2) from H2BЈ and
successively dilithiation and reaction with AlCl3. From 1,2-
C6H4(NH2)2 and AlMe3 in toluene the crystalline complex
[(Me2Al)2AlMe{C6H4(NH)2}2ؒAlMe3] was obtained.24
1,3-Di(neopentylamino)benzene H2CЈ (bp 165–167 ЊC / 5
Torr) was obtained by Li[AlH4] reduction of 1,3-bis(di-
pivaloylamino)benzene (mp 195–198 ЊC), prepared from 1,3-
diaminobenzene. Treatment of H2CЈ with two equivalents of
trimethylalane and brief heating in toluene afforded (i in
Scheme 3) after concentration and cooling, the crystalline
diamine–bis(trimethylalane) 10 in good yield. An attempt was
made to gain access to a bis(amino)dialane by first converting
H2CЈ into Li2CЈ(tmen)2 and then adding 2 equivalents of di-
methyl(chloro)alane (ii in Scheme 3). This yielded a white solid,
insoluble in hydrocarbons or dichloromethane; in order to
characterise it, tmen (2 equivalents) in thf was added. Removal
of volatiles provided (iii in Scheme 3) an orange oil in a
yield appropriate to the quantitative formation of the material
tentatively formulated as 11. This assignment was consistent
with 1H NMR spectral data in C6D6. The insoluble white solid
may well have been a polymer or oligomer of 1,3-C6H4[N(RЈ)-
AlMe2]2, which with 2 tmen reverted to the soluble monomer
11.
The reactions summarised in Schemes 1–3 lead us to the fol-
lowing conclusions regarding the relative behaviour of the tri-
methylsilyl versus neopentyl anilines or 1,2-diaminobenzenes:
(i) the neopentylamines are less prone to deprotonation than
the trimethylsilyl analogues, and (ii) it may be that the latter are
able to yield stereoselective products.
As for (i), we note that (a) HAЈ formed a 1 : 1-adduct 2 with
AlMe3 at ambient temperature which only upon prolonged
heating eliminated methane to form the amide 3, whereas
AlMe3 with HA afforded the amide 1 at ambient temperature;
(b) H2BЈ with AlMe3 under these conditions eliminated only
one equivalent of methane to give the aminometal amide 7 (the
second CH4 loss occurred at elevated temperature to yield the
diamidoaluminium compound 8), whereas H2B lost the two
equivalents of CH4 at 20 ЊC yielding the (SiMe3)2 analogue of 8.
Regarding (ii), it is inappropriate to generalise, but on the basis
of the experiments leading to [AlMe2(µ-A or µ-AЈ)]2 (1 or 3), we
note that 1 was stereospecifically the trans-isomer even in ben-
zene solution, whereas the neopentyl analogue 3 was a mixture
of cis and trans (although the crystals were of the cis-isomer).
The ambient temperature 1H NMR spectrum of 1 in
benzene-d6 revealed that the trans-structure observed in the
solid state (vide infra) was maintained in solution. The neo-
pentyl analogue 3, while cis in the crystal, was a mixture of
1
ca. 3(cis) : 2(trans) in solution (cf., the H NMR spectra). The
NMR spectra of the compounds 2, 4–7, 9 and 10 were consist-
ent with their solid state structures, which in the case of 4 and 5
1
was manifested by the appearance in both H and 13C NMR
spectra of two sets of AlMe2 signals.
Crystal structures of compounds 1–7, 9 and 10
Each pair of the phenyl and trimethylsilyl groups adopts a
trans-disposition around the Al1N1Al2N2 non-planar ring
(torsion angle 18.3Њ) of the dinuclear, C1-symmetric, crystalline
aluminium amide 1 (Fig. 1). The other geometric data (Table 1)
are unexceptional, as may be judged by comparison with those
for [AlMe2(µ-NMe2)]2, in which Al–N and Al–C bond lengths
range from 1.955 to 1.972 Å, respectively, the Al ؒ ؒ ؒ AlЈ dis-
tance is 2.815 Å, and the endocyclic bond angles vary from
88.4(3) to 91.6(3)Њ.25 A large number of complexes of formulae
Scheme 3 Synthesis of the crystalline complex 10 and the oil 11.
Reagents and conditions: i, 2 AlMe3, n-C6H14, 20 ЊC, 2 h, then PhMe and
heated to dissolve; ii, 2 LiBun, 2 tmen, n-C6H14, 0 ЊC, 1 h, then 2
AlClMe2, n-C6H14, 20 ЊC; iii, 2 tmen, thf, 20 ЊC.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
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Table 1 Selected bond lengths (Å) and angles (Њ) for 1
Table 2 Selected bond lengths (Å) and angles (Њ) for 2
Al(1) ؒ ؒ ؒ Al(2)
Al(1)–C(1)
Al(2)–C(3)
Al(1)–N(1)
Al(2)–N(1)
2.7895(12)
1.958(3)
1.967(3)
2.020(2)
2.019(2)
Al(1)–C(2)
Al(2)–C(4)
Al(1)–N(2)
Al(2)–N(2)
1.957(4)
1.963(3)
2.002(2)
1.987(2)
Al–C(1)
Al–N
1.953(3)
2.067(4)
Al–C(2)
N–C(4)
1.978(3)
1.459(9)
C(1)–Al–N
C(2)–Al–N
Al–N–C(10)
107.8(2)
106.14(16)
108.5(4)
Al–N–C(4)
C(4)–N–C(10)
115.1(5)
115.7(4)
C(2)–Al(1)–C(1)
C(1)–Al(1)–N(2)
C(1)–Al(1)–N(1)
C(4)–Al(2)–C(3)
C(3)–Al(2)–N(2)
C(3)–Al(2)–N(1)
Al(2)–N(1)–Al(1)
110.01(16)
113.22(14)
120.50(14)
108.42(15)
114.33(13)
120.19(13)
87.37(9)
C(2)–Al(1)–N(2)
C(2)–Al(1)–N(1)
N(2)–Al(1)–N(1)
C(4)–Al(2)–N(2)
C(4)–Al(2)–N(1)
N(2)–Al(2)–N(1)
Al(2)–N(2)–Al(1)
112.18(14)
110.66(13)
88.76(10)
112.83(13)
110.91(13)
89.20(10)
88.72(10)
Symmetry transformations to generate equivalent atoms : Ј x, Ϫy ϩ
1/2, z.
Table 3 Selected bond lengths (Å) and angles (Њ) for 3
Al ؒ ؒ ؒ AlЈ
Al–C(12)
Al–NЈ
2.792(1)
1.970(2)
2.029(2)
Al–C(13)
Al–N
1.968(2)
1.984(2)
[AlR1 (µ-NR2R3)]2 have been crystallographically character-
2
ised.26–28 Most are of C1 symmetry, have an almost square
(AlN)2 ring, but in some cases this is slightly puckered, as in
[AlMe2{µ-N(CH2Ph)2}]2 which has a fold angle of 4.0Њ about
the N–NЈ vector. The transoid geometry, if R2 ≠ R3, is largely
dominant, as in [AlMe2{µ-N(H)Pri}]2,29a or [AlMe2{µ-N-
(SiMe3)(CH2C4H3O-2)}]2,29b but cis-complexes are encountered,
particularly for higher AlR2 homologues, as in [AlBut2{µ-
N(H)C6H4Ph-4}]2,30a but see also [AlMe2{µ-N(CH2Ph)Pri}]2.30b
C(13)–Al–C(12)
C(12)–Al–N
C(12)–Al–NЈ
Al–N–AlЈ
109.90(11)
122.61(10)
115.02(9)
88.15(7)
C(13)–Al–N
C(13)–Al–NЈ
N–Al–NЈ
111.15(9)
107.71(9)
88.17(7)
Symmetry transformations used to generate equivalent atoms: Ј Ϫx, y,
Ϫz ϩ 1/2.
The crystalline [AlMe2(AЈ)]2 3 molecule (Fig. 3) lies on a two-
fold rotation axis orthogonal to the Al–AlЈ vector. It also differs
from 1 in its cisoid arrangement of substituents at the N- and
NЈ- atoms of the puckered AlNAlЈNЈ ring (torsion angle 20.1Њ).
The other geometric parameters (Table 3) are similar to those
of compound 1.
Fig. 1 Molecular structure of trans-[(AlMe2)(µ-(A)]2 1.
The AlMe3 group of the crystalline compound [AlMe3ؒ
H(AЈ)] 2 (Fig. 2) lies on the mirror plane, with the rest of the
molecule disordered across this plane. The geometric param-
eters are unexceptional (Table 2), as evident from a comparison
with those (by gas electron diffraction) for [AlMe3(NMe3)], hav-
ing Al–N, Al–C and N–C bond lengths of 2.099(10), 1.987(5)
and 1.474(3) Å, respectively and C–Al–N and C–N–Al bond
angles of 102.3(3) and 109.3(3)Њ, respectively.31
Fig. 3 Molecular structure of cis-[(AlMe2)(µ-AЈ)]2 3.
The crystalline [(AlMe2)2(µ-B)] 4 molecule (Fig. 4) lies on a
two-fold rotation axis, perpendicular to the Al–AlЈ vector. The
two distorted tetrahedral nitrogen atoms N and NЈ of the
ligand B are members of the strongly puckered AlNAlЈNЈ ring
Fig. 2 Molecular structure of [(AlMe3)ؒH(AЈ)] 2.
Fig. 4 Molecular structure of [(AlMe2)2(µ-B)] 4.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
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Table 4 Selected bond lengths (Å) and angles (Њ) for 4
Table 5 Selected bond lengths (Å) and angles (Њ) for 5
Al ؒ ؒ ؒ AlЈ
Al–C(8)
Al–NЈ
2.8242(12)
1.964(3)
2.0043(19)
Al–C(7)
Al–N
N–C(1)
1.959(3)
2.0041(19)
1.462(3)
Al(1) ؒ ؒ ؒ Al(2)
Al(1)–C(17)
Al(2)–C(20)
Al(1)–N(1)
Al(2)–N(2)
N(2)–C(2)
2.823(1)
1.957(3)
1.959(3)
2.011(2)
1.990(2)
1.447(3)
Al(1)–C(18)
Al(2)–C(19)
Al(1)–N(2)
Al(2)–N(1)
N(1)–C(1)
1.954(3)
1.959(3)
2.003(2)
1.977(2)
1.450(3)
C(7)–Al–N
C(7)–Al–NЈ
N–Al–NЈ
C(1)–N–AlЈ
Al–N–Si
115.79(10)
117.94(10)
77.62(9)
94.05(12)
123.70(10)
112.20(10)
C(7)–Al–C(8)
C(8)–Al–N
C(8)–Al–NЈ
C(1)–N–Al
Al–N–AlЈ
114.06(12)
113.93(11)
112.67(10)
94.14(12)
89.59(8)
C(18)–Al(1)–C(17) 115.53(14)
C(19)–Al(2)–C(20) 116.63(14)
C(18)–Al(1)–N(2)
C(18)–Al(1)–N(1)
N(2)–Al(1)–N(1)
C(1)–N(1)–Al(2)
C(2)–N(2)–Al(2)
Al(2)–N(1)–Al(1)
C(2)–C(1)–N(1)
C(7)–N(1)–Al(2)
C(12)–N(2)–Al(2)
119.63(12)
114.08(12)
75.11(8)
98.18(14)
96.78(15)
90.10(9)
110.5(2)
129.81(6)
115.32(16)
C(17)–Al(1)–N(2)
C(17)–Al(1)–N(1)
N(1)–Al(2)–N(2)
C(1)–N(1)–Al(1)
C(2)–N(2)–Al(1)
Al(2)–N(2)–Al(1)
C(1)–C(2)–N(2)
C(12)–N(2)–Al(1)
115.38(12)
110.10(12)
76.17(9)
94.81(14)
95.71(14)
89.95(9)
C(1)Ј–C(1)–N
AlЈ–N–Si
125.56(10)
Symmetry transformations used to generate equivalent atoms: Ј Ϫx ϩ
1/2, y, Ϫz ϩ 1/2.
111.1(2)
133.04(6)
(torsion angle 37.1Њ). The angles at the endocyclic aluminium
atoms are more acute than those at the nitrogen atoms, Table 4.
The ligand B is both chelating and bridging; in that respect the
structure of 4 is similar to those of [{Li(L)}2(µ-B)]2 [L = (thf )2
12, L = tmen 13], in which the Li–N distances range from
1.971(8) to 2.102(7) Å (12) and 2.056(7) to 2.078(7) Å (13).4 The
Al ؒ ؒ ؒ Al, Al–N and Al–CH3 distances are very similar to those
of 1 and 5.
Table 6 Selected bond lengths (Å) and angles (Њ) for 6
Al–N(2)
Al–N(1)Ј
N(1)–C(1)
1.8358(19)
1.9621(18)
1.478(2)
Al–C(13)
Al–N(1)
N(2)–C(2)
1.948(2)
1.9799(18)
1.401(3)
N(2)–Al–C(13)
N(2)–Al–N(1)
C(13)–Al–N(1)Ј
N(1)Ј–Al–N(1)
C(1)–N(1)–AlЈ
AlЈ–N(1)–Al
119.39(11)
91.83(8)
113.10(10)
89.62(7)
108.12(12)
90.38(7)
117.30(17)
N(2)–Al–N(1)Ј
C(13)–Al–N(1)
C(1)–N(1)–Si(1)
C(1)–N(1)–Al
C(2)–N(2)–Al
C(1)–C(2)–C(3)
115.99(9)
121.90(11)
111.58(13)
102.76(12)
109.40(14)
116.9(2)
C(2)–C(1)–N(1)
Symmetry transformations used to generate equivalent atoms: Ј Ϫx ϩ
1/2, Ϫy ϩ 1/2, Ϫz ϩ 1.
There are two independent C1-symmetric molecules in the
unit cell of crystalline [AlMe2(µ-BЈ)] 5 with essentially the same
geometry (Fig. 5); hence data for only one are listed in Table 5.
The structure is very similar to that of 4, but the torsion angle
of the Al1N1Al2N2 puckered ring of 39.1Њ is slightly wider
than the corresponding angle in 4. The spread of the four
N–Al–CH2But angles [155.32(16) to 133.04(6)Њ] is much greater
than that of the Al(AlЈ)–N–Si angles [123.70(10). 125.56(10)Њ].
Fig. 6 Molecular structure of trans-[(AlMe)(µ-B)]2 6.
around the central AlNAlЈNЈ. The atoms Al and AlЈ from each
of the terminal rings is ca. 0.2 Å out of the NCCN plane of the
AlNCCN moiety. The two nitrogen atoms of the ligand B differ
in that the four-coordinate N1 (or N1Ј) atom bridge the two
aluminium atoms Al and AlЈ, while the three-coordinate N2
(or N2Ј) is bonded to Al (or AlЈ) in a terminal fashion; hence
the Al–N1 and N1–C1 bonds are significantly longer than the
Al–N2 and N2–C2 bonds (Table 6).
The skeletal structure of the fused trinuclear ring system of 6
is very similar to that of [Mg(µ-B)(OEt2)]2 14, in which the
corresponding Mg–N1, Mg–N2, N1–C1 and N2–C2 distances
are 1.997(7), 2.082(7), 1.371(11) and 1.472(11) Å, respectively,6
and the ladder has the chair conformation. This feature has also
been found in 15 and 16, having the following geometric
parameters [16 in square brackets]: Al–N1 1.985(2) [1.966(2)],
Fig. 5 Molecular structure of [(AlMe2)2(µ-BЈ)] 5.
The crystalline [AlMe(µ-B)]2 6 molecule (Fig. 6) lies across an
inversion centre, the mid-point of the central almost square
AlNAlЈNЈ ring. It comprises an array of three aluminium-
containing fused rings in a ladder-type structure with a chair-
like transoid disposition of the terminal five-membered rings
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
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Table 7 Selected bond lengths (Å) and angles (Њ) for 7
Table 8 Selected bond lengths (Å) and angles (Њ) for 9
Al–N(2)
1.8655(12)
1.9643(15)
1.4765(16)
1.5169(17)
1.3804(19)
Al–C(17)
Al–N(1)
N(2)–C(2)
N(2)–C(12)
C(1)–C(2)
1.9590(15)
2.0234(12)
1.3782(17)
1.4555(18)
1.411(2)
Al(1) ؒ ؒ ؒ Al(2)
Al(1)–N(2)
Al(1)–Cl(1)
Al(2)–N(3)
Al(2)–Cl(2)
N(1)–C(7)
N(2)–C(12)
N(3)–C(23)
N(4)–C(28)
C(17)–C(18)
2.721(1)
1.925(2)
2.107(1)
1.920(2)
2.105(1)
1.471(3)
1.507(3)
1.508(3)
1.469(3)
1.412(4)
Al(1)–N(1)
Al(1)–N(3)
Al(2)–N(4)
Al(2)–N(2)
N(1)–C(1)
N(2)–C(2)
N(3)–C(17)
N(4)–C(18)
C(1)–C(2)
1.812(2)
1.977(2)
1.811(2)
1.973(2)
1.398(3)
1.467(3)
1.470(3)
1.405(3)
1.415(4)
Al–C(18)
N(1)–C(1)
N(1)–C(7)
C(1)–C(6)
N(2)–Al–N(1)
C(2)–N(2)–Al
N(2)–C(2)–C(1)
85.62(5)
109.83(9)
115.98(12)
C(17)–Al–C(18)
C(1)–N(1)–Al
C(2)–C(1)–N(1)
115.09(7)
101.62(8)
115.13(11)
N(1)–Al(1)–N(2)
N(4)–Al(2)–N(3)
N(1)–Al(1)–N(3)
C(1)–N(1)–Al(1)
Al(1)–N(2)–Al(2)
C(17)–N(3)–Al(1)
C(18)–N(4)–Al(2)
C(1)–C(2)–N(2)
90.71(10)
91.10(9)
115.69(10)
111.58(17)
88.52(9)
103.32(15)
110.98(17)
115.3(2)
N(2)–Al(1)–N(3)
N(3)–Al(2)–N(2)
N(4)–Al(2)–N(2)
C(2)–N(2)–Al(1)
C(17)–N(3)–Al(2)
Al(2)–N(3)–Al(1)
N(1)–C(1)–C(2)
90.47(9)
90.74(9)
115.28(10)
105.98(15)
106.09(16)
88.53(9)
Al–N 1.949(2) [1.812(2)], Al–NЈ 1.975(2) [1.940(2)], N1–C1
1.465(3) [1.479(3)], N2–C2 1.383(3) [1.386(3)] Å; N1–Al–N1Ј
86.83(8) [87.73(7)], and Al–N–AlЈ 93.47(8) [92.27(7)]Њ.32 By
contrast, the corresponding saturated compound with X = H
(i.e., with –NCH CH N– in place of –NCH᎐CHN–) was
᎐
2
2
obtained both in the chair (trans-) and the boat (cis-) form.33
This type of isomerisation has been discussed in related gallium
compounds.34 The structure of [(AlMe2)2{µ-trans-N(R)(C6H11-
c)}] has recently been reported.35
116.1(2)
C(18)–C(17)–N(3) 115.0(2)
The 2-aminophenylamidodi(methyl)aluminium compound
[AlMe2{µ-H(BЈ)}] 7 (Fig. 7) crystallised in a mononuclear
C1-symmetric fashion. The chelating ligand H(BЈ) has Al–N
and contiguous N–C bonds shorter for the three-coordinate
(N2) than for the four-coordinate (N1) nitrogen atoms (the NH
hydrogen atom was not located), Table 7. The torsion angle
between the N1–Al–N2 and the 1,2-NC6H4N plane is 30.24(5)Њ.
The aluminium atom is 0.706 Å out of the latter plane. The
endocyclic bond angles of the AlN1C1C2N2 ring range from
85.62(5)Њ at Al to 115.98(12)Њ at C2. The Al–CH3 bond lengths
are similar to those in 1 or 3. Compound 7 has some structural
similarity to the complexes 17 and 18, which have Al–N dis-
tances of 1.968(11) and 1.897(2) Å (17) and 2.045(4) and
1.856(4) Å (18) for the dative and covalent bonds, respectively.36
Fig. 8 Molecular structure of [(AlCl)(µ-BЈ)]2 9.
than square, as in 6) central AlN2AlN3 core. The latter has
endocyclic bond angles at N2 and N3 which are slightly nar-
rower than those at the Al1 and Al2 atoms, Table 8. The
aromatic rings are almost parallel and staggered. As in 6, the
Al–N and contiguous N–C bonds of each AlNCCN ring
are longer for those involving the four- (N2, N3) rather than the
three- (N1, N4) coordinate nitrogen atoms.
In the five complexes 4–7 and 9 containing a 1,2-N,NЈ-di-
substituted ligand B or BЈ, the C1–C2 bond of the C6 ring is
invariably the longest, ranging from 1.407(4) Å in 4 to 1.418(4)
Å in 5. The shortest bonds are the C3–C4, C4–C5 and C5–C6,
which vary from 1.37 to 1.39 Å.
The crystalline C1-symmetric molecule [(AlMe3)2ؒH2(CЈ)] 10
(Fig. 9), like 2, has a four-coordinate tetrahedral environment
about each aluminium atom, with Al–CH3 and Al–N bond
lengths (Table 9) very slightly longer than those of 2 and C–Al–
N angles significantly narrower (by ca. 2 to 6Њ) than those of 2
(Table 1).
Fig. 7 Molecular structure of trans-[(AlMe2)(µ-HBЈ)] 7.
Crystals of [AlMe(µ-BЈ)]2 8 diffracted poorly, but the data
were adequate to establish that its dimeric structure was similar
to that of 6. However, X-ray quality single crystals of the corre-
sponding C1-symmetric chloride [AlCl(µ-BЈ)]2 9 were obtained
(Fig. 8). In its three fused ladder-type aluminium containing
rings it resembles those of 6, but in 9 there is a boat-like cisoid
disposition [cf. ref. 33) of the terminal five-membered rings
around the almost rhomboidal (torsion angle 10.1Њ) (rather
Experimental
All manipulations were carried out under argon or in vacuo
using standard Schlenk techniques. Solvents were pre-dried
over sodium, distilled from sodium (toluene), sodium–
potassium alloy (pentane, hexane) or sodium–benzophenone
(diethyl ether, tetrahydrofuran) and stored over a potassium
mirror or molecular sieves (4 Å). Deuteriated solvents were
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
1825

View Article Online
Table 9 Selected bond lengths (Å) and angles (Њ) for 10
thf and filtered. The filtrate was concentrated. Distillation of
the residue under reduced pressure gave H2(CЈ) as a colourless
crystalline solid (22.4 g, 73%) (Found: C, 77.6; H, 11.29; N,
11.41. C18H28N2 requires C, 77.4; H, 11.29; N, 11.29%), bp 165–
Al(1)–C(12)
Al(1)–C(14)
Al(2)–C(21)
Al(1)–N(1)
N(1)–C(1)
1.9714(19)
1.9756(18)
1.9670(18)
2.0864(13)
1.4532(17)
Al(1)–C(13)
Al(2)–C(22)
Al(2)–C(20)
Al(2)–N(2)
N(2)–C(3)
1.9744(19)
1.9641(19)
1.9794(18)
2.0811(13)
1.4544(18)
1
167 ЊC/5 Torr. H NMR (CDCl3): δ 1.04 (s, 18H, Me), 2.92 (s,
4H, NCH2), 3.85 (br s, 2H, NH), 6.0–7.05 (m, 4H, Ph); 13C
NMR (CDCl3): δ 28.2 (Me), 32.1 (CCH3), 56.5 (NCH2), 97.7,
103.2, 130.3, 150.4 (Ph), EI-MS (m/z, %): 248 {83, [M]ϩ}, 191
{100, [M Ϫ But]ϩ}.
C(13)–Al(1)–N(1)
C(22)–Al(2)–N(2)
C(20)–Al(2)–N(2)
C(3)–N(2)–Al(2)
101.43(7)
103.44(7)
99.84(7)
C(12)–Al(1)–N(1)
C(14)–Al(1)–N(1)
C(21)–Al(2)–N(2)
C(1)–N(1)–Al(1)
104.05(7)
102.10(7)
104.32(7)
110.42(9)
110.34(9)
[AlMe2(ꢀ-A)]2 1. A solution of AlMe3 (11 cm3 of a 2.0 mol
dmϪ3 solution in hexanes, 22 mmol) was added dropwise at
ca. 0 ЊC to a solution of H(A) (3.55 g, 21.5 mmol) in hexane
(10 cm3). The colourless solution was stirred for 1 h at ca. 20 ЊC.
Volatiles were removed in vacuo and the resulting oil was briefly
heated in vacuo at <60 ЊC until a white solid had formed. Crys-
tallisation from hexane at Ϫ25 ЊC yielded colourless needles of
compound 1 (4.08 g, 92%) (Found; C, 57.6 (duplicate analyses);
H, 8.80; N, 6.11. C22H40Al2N2Si2 requires C, 59.7; H, 9.11; N,
6.33%), mp 130–132 ЊC. 1H NMR: δ Ϫ0.07 (s, 6H, AlMe), 0.09
(s, 9H, SiMe), 7.0–7.33 (m, 5H, Ph); 13C NMR: δ 0.4 (AlMe),
2.6 (SiMe), 125.2–144.1 (Ph); 27Al NMR: δ 164.5 (br s, ∆w 5.8
½
kHz); 29Si NMR: δ 14.2.
[AlMe3ؒH(AЈ)] 2. A solution of AlMe3 (5 cm3 of a 2.0 mol
dmϪ3 solution in hexanes, 10.0 mmol) was added dropwise at
ca. 0 ЊC to a solution of H(AЈ) (1.58 g, 9.68 mmol) in hexane
(20 cm3), then stirred for 1 h at ca. 20 ЊC. Volatiles were removed
in vacuo and the resulting white solid was crystallised from
pentane at Ϫ25 ЊC, yielding colourless needles of compound 2
(2.07 g, 91%) (Found: C, 68.1; H, 10.93; N, 5.80. C14H26AlN
requires C, 71.5; H, 11.14; N, 5.95%), mp 39–40 ЊC. 1H NMR:
Fig. 9 Molecular structure of [(AlMe3)2ؒH2(CЈ)] 10.
likewise stored over such molecular sieves and degassed prior to
use. Triethylamine, chloro(trimethyl)silane, lithium aluminium
hydride, pivaloyl chloride, AlMe3, AlCl3 and n-butyllithium in
hexanes (1.6 mol dmϪ3, FMC corporation) were commercial
samples used without further purification. The NMR solution
spectra were recorded on Bruker DPX 300 (for 1H and 13C) or
AMX 500 (for 29Si and 27Al) instruments and referenced exter-
nally (using aqueous Al(OH)3 with a D2O lock for 27Al or SiMe4
for 29Si) or internally (1H, 13C) to the residual solvent reson-
ances; chemical shift data in δ. Unless otherwise stated, all
NMR spectra were examined at 293 K in C6D6 and, except for
1H, were proton decoupled. Electron impact mass spectra were
taken on a Kratos MS 80 RF instrument. Elemental analyses
(empirical formulae shown) were carried out by Medac Ltd,
UK., Brunel University. Melting points were taken in sealed
capillaries and are uncorrected.
3
δ Ϫ0.47 (s, 9H AlMe), 0.46 (s, 9H, CMe3), 2.96 (d, JHH = 5.8,
2H, NCH2), 3.80 (t, 3JHH = 5.8 Hz, 1H, NH), 6.56–7.15 (m, 5H,
Ph); 13C NMR: δ Ϫ8.7 (AlCH3), 27.6 (CCH3), 32.7 (CCH3),
60.9 (NCH2), 121.2–144.1 (m, Ph); 27Al NMR: δ 183.6 (br s,
∆w 4.5 kHz).
½
[AlMe2(ꢀ-AЈ)]2 (cis 3 ؉ trans). A solution of 2 (2.06 g, 8.75
mmol) in hexane (20 cm3) was refluxed for 16 h. Upon cooling,
colourless crystals of 3 were obtained (1.37 g, 71%) (Found: C,
69.5; H, 10.10; N, 6.53. C26H44Al2N2 requires C, 71.2; H, 10.11;
N, 6.39%), mp 164 ЊC (subl.). 1H NMR: δ Ϫ0.29 (s, 6H, AlMe
of cis), Ϫ0.20 (s, 12H, AlMe of trans), Ϫ0.03 (s, 6H, AlMe of
cis), 3.30 s, (4H, NCH2 of trans), 3.36 (4H, NCH2 of cis), 6.81–
7.43 (m, 20H, Ph); 13C NMR: δ Ϫ4.1 (AlMe of cis), Ϫ3.5
(AlMe of trans), Ϫ1.7 (AlMe of cis), 29.9 (CCH3 of cis), 30.0
(CCH3 of trans), 34.0 (CCH3), 61.8 (NCH2 of cis), 63.8 (NCH2
Preparations
of trans), 124.5–148.2 (Ph); 27Al NMR: δ 173.2 (br s, ∆w
6
1,3-Bis(pivaloylamino)benzene. A solution of pivaloyl chlor-
ide (45.0 g, 373 mmol) in thf (100 cm3) was added dropwise
at ca. 20 ЊC to a solution of 1,3-diaminobenzene (20.0 g,
185 mmol) and triethylamine (38 g, 374 mmol) in thf (900 cm3).
The resulting thick white suspension was stirred overnight.
Volatiles were removed in vacuo and the resulting solid was
washed several times with water, dried and crystallised from
½
kHz). MS (m/z, %): 57 (84, [C(CH3)3ϩ]), 162 (100, [PhNCH2-
But]ϩ), 204 (73, [PhN(CH2But)AlMe]ϩ), 219 (66, [PhN(CH2-
But)AlMe2]ϩ), 423 (30, [{PhN(CH2But)AlMe2}2 Ϫ Me]ϩ).
[(AlMe2)2(ꢀ-B)] 4. Compound H2(B) (1.21 g, 4.80 mmol) was
dissolved in hexane (100 cm3) at 0 ЊC and AlMe3 (5 cm3 of a
2.0 mol dmϪ3 solution in hexanes, 10.0 mmol) was added drop-
wise over 5 min. The solution was set aside for 30 min at 0 ЊC,
then 2 h at ca. 20 ЊC. Hexane was partially removed in vacuo
and the clear solution left at 0 ЊC for crystallisation, yielding
colourless crystals of compound 4 (1.67 g, 95%) (Found: C,
51.8 (duplicate analyses); H, 9.67; N, 7.13. C16H34Al2N2Si2
hot ethanol, to give 1,3-bis(pivaloylamino)benzene as
white solid (34.6 g, 68%) (Found: C, 69.6; H, 8.70; N, 10.14.
a
C16H24N2O2 requires C, 69.7; H, 8.80; N, 10.07%), mp 195–
1
198 ЊC. H NMR (CDCl3): δ 1.32 (s, 18H, Me), 7.23–7.35 (m,
3H, Ph), 7.93 (s, 1H, Ph), 7.46 (br s, 2H, NH); 13C NMR
(CDCl3): δ 27.9 (CH3), 40.0 (CCH3), 111.7, 115.8, 129.7, 138.9
(Ph), 177.2 (CO). EI-MS (m/z, %): 276 {43, [M]ϩ}, 57 {100,
[But]ϩ}.
1
requires C, 52.7; H, 9.40; N, 7.68%), mp 55–57 ЊC. H NMR:
δ Ϫ0.97 (s, 6H, AlMe), 0.06 (s, 6H, AlMe), 0.21 (s, 18H, SiMe3),
6.76 (m, 2H, m-C6H4) 6.88 (m, 2H, o-C6H4); 13C NMR: δ Ϫ10.5
and Ϫ2.9 (AlMe), 0.3 (SiMe3), 118.8 (m-H), 123.2 (o-H), 142.4
1,3-Bis(neopentylamino)benzene H2(CЈ). Solid 1,3-bis(pival-
oylamino)benzene (34.3 g, 124 mmol) was added to a cooled
(0 ЊC) suspension of Li[AlH4] (19.0 g, 500 mmol) in thf (400
cm3). After 2 h at ca. 25 ЊC and 12 h at reflux, the grey suspen-
sion was carefully hydrolysed at 0 ЊC by a mixture of water and
(ipso-C); 27Al NMR: δ 171.1 (br ∆w 2.3 kHz); 29Si NMR:
½
δ Ϫ8.84. MS (m/z, %): 584 (20, [AlMe(B)]2ϩ) 364 (10, [Al2-
Me4(B)]ϩ), 349 (100, [Al2Me3(B)]ϩ), 292 (100, [AlMe(B)]ϩ), 277
(65, [Al(B)]ϩ), 261 (15, [Al(B) Ϫ MeH]ϩ), 73(55, [SiMe3]ϩ).
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
1826

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[(AlMe2)2(ꢀ-BЈ)] 5. A solution of AlMe3 (6.1 cm3 of a 2.0 mol
dmϪ3 solution in hexanes, 12.2 mmol) was added dropwise at
ca. 0 ЊC to a solution of H2(B) (1.50 g, 6.05 mmol) in hexane
(30 cm3). The pale orange solution was stirred for 1 h at
ca. 20 ЊC. The volume of the reaction mixture was reduced to
ca. 10 cm3. Cooling at 0 ЊC yielded large colourless crystals of
compound 5 (1.44 g, 67%) (Found: C, 65.9; H, 10.41; N, 7.64.
C20H38Al2N2 requires C, 66.6; H, 10.62; N, 7.77%), mp 78 ЊC
1
(decomp.). H NMR: δ Ϫ0.90 (s, 6H, AlMe), Ϫ0.08 (s, 6H,
AlMe), 0.90 (s, 18H, CMe), 2.92 (s, 4H, NCH2), 6.73–6.85 (m,
4H, Ph); 13C NMR: δ Ϫ11.1 (AlMe), Ϫ5.4 (AlMe), 29.4
(CCH3), 33.7 (CCH3), 56.6 (NCH2), 114.1–142.8 (Ph); 27Al
NMR: δ 167.4 (br s, ∆w 10 kHz).
½
[(AlMe)(ꢀ-B)]2 6. Compound H2(B) (1.32 g, 5.23 mmol) was
dissolved in hexane (100 cm3) at 0 ЊC and AlMe3 (2.6 cm3, of a
2.0 mol dmϪ3 solution in hexanes, 5.2 mmol) was added drop-
wise over 5 min. The solution was set aside for 30 min at 0 ЊC,
then 2 h at ca. 20 ЊC. Hexane was partially removed in vacuo
and the clear solution left at 0 ЊC for crystallisation, yielding
colourless crystals of compound 6 (1.32 g, 85%) (Found: C,
52.3 (duplicate analyses); H, 8.60; N, 8.89 (duplicate analyses).
C26H50Al2N2Si2 requires C, 53.4; H, 8.61; N, 9.58%), mp 95 ЊC
(decomp.). 1H NMR: spectrum appears to be that of a mixture
of three isomers ([(AlMe)(µ-B)]2 I, 50%; [(AlMe)(µ-B)] II, 37%
and [µ-Al(Me)(B)]2 III, 13%): δ Ϫ0.47 (s, I), Ϫ0.42 (s, III) and
0.10 (s, II) [total 6H, AlMe], 0.11 (2d, I), 0.31 (2s, III), 0.38 (2s,
II) [total 36H, SiMe3], 6.48 (t), 6.58 (t) 6.62–6.66 (m), 6.85–7.07
(4 m) [total 8H, C6H4]; 13C NMR: δ Ϫ4.9 (m, AlMe), 1.4, 2.0
( 2 s, SiMe3), 115.4–119.3 (6s), 125.9, 126.3, 135.2, 135.6, 149.7,
150.7 (Ph); 27Al NMR: δ 153.0 (br ∆w = 8 kHz); 29Si NMR:
½
δ Ϫ0.56, Ϫ1.4. MS (m/z, %): 584 (35, [AlMe(B)]2ϩ), 569 (10,
[Al(B) Ϫ H]2ϩ), 292 (100, [AlMe(B)]ϩ), 277 (55, [Al(B)]ϩ), 261
(15, [Al(B) Ϫ MeH]ϩ), 247 (50, [Al(B) Ϫ 2Me]ϩ), 73 (55,
[SiMe3]ϩ).
[(AlMe2){ꢀ-(H)BЈ}]2 7. A solution of AlMe3 (4.23 cm3 of a
2 mol dmϪ3 solution in hexanes, 8.47 mmol) was added to a
solution of H2(BЈ) (2.1 g, 8.47 mmol) in hexane (30 cm3), at
Ϫ40 ЊC. The solution was slowly warmed to ambient temper-
ature and stirred for 3 h, then reduced to about 15 cm3 and
cooled to Ϫ25 ЊC to afford colourless crystals of compound 7
(1.98 g, 77%) (Found: C, 69.4; H, 10.82; N, 9.11. C18H33AlN2
requires C, 71.0; H, 10.92, N, 9.20%), mp 55–57 ЊC. 1H NMR:
δ Ϫ0.26, Ϫ0.21 (2 s, 6H, AlMe), 0.69, 1.19 (2 s, 18H, But), 2.32
(d, 1H, NH), 3.29 (s, 2H, CH2), 3.19, 3.23, 3.25 (AB-type, partly
overlapped with other CH2 signal, 2H, CH2), 6.53–6.58, 6.76–
6.79, 6.9–6.93, 7.21–7.27 (m, 4H, Ph); 13C NMR: δ Ϫ9.5, Ϫ8.28
(AlMe), 27.36, 28.87 (CMe3), 30.78, 34.52 (CMe3), 57.86, 64.67
(CH2), 112.27, 112.5, 123.76, 129.48, 131.71, 153.69 (Ph); 27Al
NMR: δ 169.5, ∆w 6 kHz. MS (m/z, %): 304 (7, [M]ϩ), 289
½
(11, [M Ϫ Me]ϩ).
[(AlMe)(ꢀ-BЈ)]2 8. Compound 7 (1.6 g, 5.26 mmol) was dis-
solved in toluene (30 cm3) and heated for 2 d at 100 ЊC. The
solvent was removed and the residue extracted into hexane.
After filtration and cooling of the filtrate at Ϫ25 ЊC colourless
crystals of compound 8 were obtained (1.05 g, 70%) (Found: C,
70.1; H, 10.16; N, 9.81. C34H58Al2N4 requires C, 70.8; H, 10.13;
N, 9.71%), mp 163–165 ЊC. Alternatevely, 8 was synthesised
directly from H2(BЈ) and AlMe3 by heating an equimolar mix-
1
ture in toluene for 2 d at 100 ЊC. H NMR: δ Ϫ0.2 (br s, 3H,
AlMe), 0.88 (br s, 18H, But), 2.75, 2.8, 3.12, 3.17 (AB-type, 4H,
CH2), 6.63–6.68 (m, 4H, Ph); 13C NMR (338 K): δ Ϫ9.4
(AlMe), 29.9 (CMe3), 34.3 (CMe3), 58.7 (CH2), 116.9, 119.5,
143.0 (Ph); 27Al NMR (338 K): δ 75 ∆w 3.2 kHz. MS (m/z, %):
½
576 (11, [M]2ϩ), 288 (100, [M]ϩ).
[(AlCl)(ꢀ-BЈ)]2 9. A solution of LiBun (15.37 cm3 of a 1.6 mol
dmϪ3 solution in hexane, 24.6 mmol) was added to a solution of
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
1827

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H2(BЈ) (3.05 g, 12.3 mmol) in toluene (50 cm3). The suspen-
sion was stirred for 1 h, cooled to Ϫ78 ЊC and AlCl3 (1.64 g,
12.3 mmol) was added. The mixture was slowly warmed to
ambient temperature and stirred for 16 h. The precipitate was
filtered off and the solvent removed from the filtrate in vacuo.
The remaining solid was dissolved in hexane and first frozen in
liquid N2 and then stored at Ϫ25 ЊC for several days to afford 9
as a beige solid (1.85 g, 49%) (it was too labile for elemental
analysis), mp 45–50 ЊC (decomp.). 1H NMR: δ 0.89 (s, 9H, But),
References
1 M. F. Lappert, P. P. Power, A. R. Sanger and R. C. Srivastava,
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3 J.-P. Bezombes, P. B. Hichcock, M. F. Lappert and P. G. Merle,
J. Chem. Soc., Dalton Trans., 2001, 816.
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5 L. J.-M. Pierssens, D.Phil. Thesis, University of Sussex, 1997.
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Z. Anorg. Allg. Chem., 1995, 621, 1922.
1
3.05 (vbr quartet, 4H, CH2), 6.49–6.54 (m, 4H, Ph); H NMR
(343 K): δ 0.92 (s, 9H, But), 2.99, 3.02, 3.12, 3.15 (AB-type, 4H,
CH2), 6.54–6.59 (m, 4H, Ph); 13C NMR (343 K): δ 29.83
(CMe3), 34.17 (CMe3), 59.52 (CH2), 117.8, 120.75, 140.93
(Ph); 27Al NMR: δ 115.2 ∆w 3 kHz. MS (m/z, %): 273 (6%,
½
[M Ϫ Cl]ϩ).
[(AlMe3)2ؒH2(CЈ)] 10. A solution of AlMe3 (8.5 cm3 of
2.0 mol dmϪ3 solution in hexanes, 17.0 mmol) was added drop-
wise at ca. 0 ЊC to a solution of H2(CЈ) (2.00 g, 8.06 mmol) in
hexane (30 cm3). The pale green suspension was stirred for 2 h
at ambient temperature. Toluene (40 cm3) was added and the
reaction mixture was heated until complete dissolution was
achieved. Upon cooling, colourless crystals of compound 10
formed (2.50 g, 79%) (Found: C, 65.9; H, 11.88; N, 7.18.
C22H46Al2N2 requires C, 67.3; H, 11.81; N, 7.14%), mp 137–
139 ЊC. 1H NMR: δ Ϫ0.55 (s, 18H, AlMe), 0.55 (s, 18H, CMe),
3.30 (d, 3JHH = 5.7, 4H, NCH2), 3.83 (t, 3JHH = 5.7 Hz, 2H, NH),
6.62–6.73 (m, 4H, Ph); 13C NMR: δ Ϫ8.6 (AlMe), 27.7 (CCH3),
32.8 (CCH3), 61.2 (NCH2), 113.7–145.5 (Ph); 27Al NMR: δ
9 S. Danièle, P. B. Hitchcock and M. F. Lappert, Chem. Commun.,
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190.6 (br s, ∆w 11 kHz).
½
[{AlMe2(tmen)}2(ꢀ-CЈ)] 11. A solution of LiBun (12.0 cm3 of
a 1.6 mol dmϪ3 solution in hexane, 19.2 mmol) was added to a
solution of H2(CЈ) (2.23 g, 9.0 mmol) and tmen (2.30 g, 19.8
mmol) in hexane (20 cm3). The suspension was stirred 1 h at ca.
25 ЊC, then added at ca. 0 ЊC to a solution of AlClMe2 (19.0 cm3
of a 1.0 mol dmϪ3 solution in hexanes, 19.0 mmol). The
beige suspension was stirred for 2 h at ca. 25 ЊC, then filtered.
Volatiles were removed from the filtrate in vacuo. The residual
white solid was washed with hexane and dried in vacuo to give
compound 10 (3.16 g, 97%), which was not soluble in hydro-
carbons or chlorinated solvents and was not characterised.
Addition of 2 equivalents of tmen in thf, followed by removal
of volatiles under moderate vacuum, produced the adduct
16 (a) T. M. Cameron, I. Ghiviriga, K. A. Abboud and J. M. Boncella,
Organometallics, 2001, 20, 4378; (b) T. M. Cameron, C. G. Ortiz,
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1
11, as an orange oil in quantitative yield. H NMR: δ Ϫ0.39
(s, 12H, AlMe), 1.02 (s, 18H, CMe3), 1.98 (s, 24H, NMe3),
2.37 (s, 8H, NCH2 of tmen), 3.42 (s, 4H, NCH2), 6.59–7.20
(m, 4H, Ph).
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Crystallography
Diffraction data were collected on a Enraf-Nonius Kappa-
CCD diffractometer at 173(2) K, using monochromated
Mo-Kα radiation, λ = 0.71073 Å. Crystals were mounted on the
diffractometer under a stream of cold nitrogen gas at 173 K.
The structures were refined on all F 2 with H atoms in riding
mode, using SHELXL-97.37 Further details for are found in
Table 10.
CCDC reference numbers 202056–202064.
See http://www.rsc.org/suppdata/dt/b3/b300957m/ for crys-
tallographic data in CIF or other electronic format.
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Acknowledgements
We thank the European Commission for the award of a
Marie Curie fellowships for P. G. M., the Leverhulme Trust
for a fellowship for J. P. B and the EPSRC for an Advanced
Fellowship for B. G. and other support.
30 (a) J. J. Byers, B. Lee, W. T. Pennington and G. H. Robinson,
Polyhedron, 1992, 11, 967; (b) O. M. Kekia, L. K. Krannich,
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
1828

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37 G. M. Sheldrick, SHELXL 97, Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 2 1 – 1 8 2 9
1829