Synthesis and crystal structures of trimethylindium adducts with bidentate and macrocyclic tertiary amines

Article abstract of DOI:10.1039/b008600m

The structures of trimethylindium (Me₃In) adducts with the bidentate tertiary amine N,N,N′,N′-tetramethyl-4,4′-methylenebis(aniline)[MBDA] and the macrocyclic amines 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane [N₄-aza crown] and 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane [N₆-aza crown] have been determined by single crystal X-ray diffraction. The adducts have the following stoichiometries, Me₃In·2MBDA 1, 2Me₃In·MBDA 2, 4Me₃In·N₄-aza crown 3 and 6Me₃In·N₆-aza crown 4. Compound 1 contains five-coordinate Me₃In in a trigonal bipyramidal configuration and displays the longest In-N bond lengths yet reported (2.720(4), 2.865 A); 2-4 contain four-coordinate Me₃In molecules in a tetrahedral configuration. Compounds 1-4 can be used as intermediate adducts in the adduct purification of Me₃In for use in the MOVPE (metal organic vapour phase epitaxy) of InP and related III-V semiconductors. The Royal Society of Chemistry 2001.

Full text of DOI:10.1039/b008600m

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Synthesis and crystal structures of trimethylindium adducts with
bidentate and macrocyclic tertiary amines
Kathleen M. Coward,a Anthony C. Jones,*a Alexander Steiner,a Jamie F. Bickley,a
Lesley M. Smithb and Martyn E. Pemblec
a Department of Chemistry, University of Liverpool, Liverpool, UK L69 7ZD.
Tel./Fax: 0151 493 2441; E-mail: tony@tjconsultancy.demon.co.uk
b Epichem Limited, Power Road, Bromborough, Wirral, Merseyside, UK CH62 3QF
c Department of Chemistry, University of Salford, Salford, UK M5 4WT
Received 23rd August 2000, Accepted 27th October 2000
First published as an Advance Article on the web 13th December 2000
The structures of trimethylindium (Me3In) adducts with the bidentate tertiary amine N,N,NЈ,NЈ-tetramethyl-
4,4Ј-methylenebis(aniline)[MBDA] and the macrocyclic amines 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclo-
tetradecane [N4-aza crown] and 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane [N6-aza
crown] have been determined by single crystal X-ray diffraction. The adducts have the following stoichiometries,
Me3Inؒ2MBDA 1, 2Me3InؒMBDA 2, 4Me3InؒN4-aza crown 3 and 6Me3InؒN6-aza crown 4. Compound 1
contains five-coordinate Me3In in a trigonal bipyramidal configuration and displays the longest In–N bond
lengths yet reported (2.720(4), 2.865 Å); 2–4 contain four-coordinate Me3In molecules in a tetrahedral
configuration. Compounds 1–4 can be used as intermediate adducts in the adduct purification of Me3In
for use in the MOVPE (metal organic vapour phase epitaxy) of InP and related III–V semiconductors.
1 Introduction
Tertiary amine adducts of trimethylindium (Me3In) have
been known for many years,1 but relatively little structural
information exists for these compounds. Recently there has
been revived interest in trimethylindium–trialkylamine adducts
as they are useful both as precursors in the metal organic
vapour phase epitaxy (MOVPE) of InP and related III–V
semiconductors,2,3 and in the purification of Me3In for sub-
sequent use in MOVPE.4 For instance, the volatile adducts
Me3InؒNR3 (R = Me or Et) have been used as precursors for
the MOVPE of InP,2,3 whilst the less volatile adduct 2Me3Inؒ
MBDA (MBDA = N,N,NЈ,NЈ-tetramethyl-4,4Ј-methylenebis-
(aniline)) has been used for purification of Me3In by mild
thermal dissociation of the adduct.4,5
The amine ligand used in adduct purification must form a
relatively weak donor–acceptor bond with the metal alkyl,
Fig. 1 Bidentate and macrocyclic tertiary amines used in this study:
allowing thermal dissociation of the adduct at relatively low
temperatures (<150 ЊC) and must also be significantly less
volatile than the liberated organometallic compound to allow
easy separation.6 There are relatively few nitrogen donors which
fulfil these criteria, for example the adducts Me3InؒNMe3,
(a) MBDA, (b) N4-aza crown and (c) N6-aza crown.
purification using MBDA.10 Device data have been reported for
a high quality low-oxygen content InAlGaAs GRINSCH laser
structure grown by MOVPE using Me3In purified by thermal
dissociation of Me3Inؒ2MBDA. In this paper full structural
details are given for the adducts Me3Inؒ2MBDA 1 and
2Me3InؒMBDA 2.
2,3
Me3InؒNEt3 and Me3InؒN(CH2CH2)3N7 all volatilise with-
out appreciable dissociation. However, quantitative yields of
high purity Me3In have been obtained by thermal dissociation
of the 2Me3InؒMBDA adduct.4,5
The rapid growth of MOVPE as a production technology
for optoelectronic devices based on AlGaAs, AlGaInAs and
AlGaInP is placing increasingly stringent requirements on the
purity of the Group III metal organic precursor. Trace oxygen
is a particular problem in Al-containing III–V devices, seriously
degrading luminescence efficiency,8 and diethyl ether (a com-
mon solvent in organometallic synthesis) has been identified
as a major source of oxygen contamination in III–V materials
grown by MOCVD.9 It is therefore necessary completely to
eliminate diethyl ether from the metal organic synthesis route.
Recently we have shown that ultra high purity Me3In, essen-
tially free from oxygen impurities, can be obtained by synthesis
of the compound in a hydrocarbon solvent, followed by adduct
We have previously shown that the macrocyclic amines
1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclooctadecane (N4-aza
crown) and 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaaza-
cyclooctadecane (N6-aza crown) (Fig. 1) form adducts which
dissociate at low/moderate temperatures with triethylgallium,11
triisopropylgallium,11 and dimethylzinc.12 In this paper we
report the synthesis and full structural characterisation of
the analogous trimethylindium compounds, 4Me3InؒN4-aza
crown 3 and 6Me3InؒN6-aza crown 4, and show that 1–4 also
dissociate at relatively low temperature to liberate base-free
Me3In. Although adducts between R3Ga and R3Al and macro-
cyclic amines have been reported,13–15 very few analogous Me3In
adducts have been reported16 and structural data are scarce.
DOI: 10.1039/b008600m
J. Chem. Soc., Dalton Trans., 2001, 41–45
This journal is © The Royal Society of Chemistry 2001
41

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Table 1 Crystal and data collection parameters for Me3Inؒ2MBDA 1, 2Me3InؒMBDA 2, 4Me3InؒN4-aza crown 3 and 6Me3InؒN6-aza crown 4
1
2
3
4
Empirical formula
Formula weight
C37H53InN4
668.76
C23H40In2N2
574.29
C26H64In4N4
892.22
C36H96In6N6
1302.30
Crystal system
Space group
Triclinic
P1
Monoclinic
P21/c
Monoclinic
P21/n
Monoclinic
P21/c
¯
a/Å
b/Å
c/Å
α/Њ
10.641(5)
10.763(4)
16.634(4)
108.27(3)
91.13(4)
105.45(4)
1732.5(11)
2
18.113(3)
8.3668(7)
18.058(3)
7.8656(11)
18.871(3)
12.6821(18)
10.6624(16)
22.856(3)
11.6461(17)
β/Њ
106.182(18)
96.714(17)
108.184(17)
γ/Њ
V/Å3
2628.3(6)
4
1.621
1869.5(5)
4
2.266
2696.5(7)
2
2.355
Z
µ/mmϪ1
0.637
Reflections collected
Reflections unique (Rint
R1 [I > 2σ(I)]
wR2 (all data)
9330
4310 (0.0813)
0.0370
16126
10131
16905
)
4152 (0.0506)
0.0317
0.0805
2531 (0.0581)
0.0640
0.1780
4251 (0.0443)
0.0256
0.0580
0.0809
2 Experimental
General techniques
Trimethylindium was supplied by Epichem Limited. The
nitrogen donor ligands used were MBDA, N4-aza crown and
N6-aza crown. All were purchased from Aldrich Chemical Co.,
dried by distillation off sodium wire and deoxygenated before
use.
1H NMR spectroscopy was carried out using a Bruker 300
spectrometer and infrared spectroscopy on a Perkin-Elmer
1000 infrared Fourier Transform spectrometer using Nujol
mulls between NaCl plates. Elemental microanalyses were
carried out by the Chemistry Department service at Liverpool
University.
Fig. 2 Crystal structure of Me3Inؒ2MBDA 1.
Adduct synthesis
The same general synthesis method was used for compounds
1–4. This involved addition of the amine [MBDA (0.5 mol
equivalent, 2 mol equivalent), N4-aza crown (0.25 mol equiv-
alent) or N6-aza crown (0.17 mol equivalent)] to a stirred
suspension of Me3In (1 mol equivalent) in toluene. Removal
of the toluene in vacuo gave 1–4 as crystalline solids which
6Me3InؒN6-aza crown 4. Colourless crystalline solid. mp
103–104 ЊC. 1H NMR (C6D6, 300 MHz, 20 ЊC): δ Ϫ0.12[s, 36H,
InCH3], 1.95[s, 18H, NCH3] and 2.51[broad s, 24H, NCH2-
CH2N]. IR (cmϪ1): 2274w, 1648w, 1302m, 1285w, 1210m,
1142m, 1121w, 1091m, 1067w, 1022m, 992m, 947w, 917m,
858w, 787w and 685s. Found: C, 33.30; H, 7.50; N, 6.7%. Calc.
for C6H16InN: C, 33.19; H, 7.44; N, 6.45%.
1
were characterised by H NMR, IR spectroscopy, elemental
microanalysis and single crystal X-ray diffraction.
Single crystal X-ray diffraction
Me3Inؒ2MBDA 1. Colourless crystalline solid. mp 71–72 ЊC.
1H NMR (C6D6, 300 MHz, 20 ЊC): δ Ϫ0.19[s, 9H, InCH3],
2.37[s, 24H, NCH3], 3.75[s, 4H, CCH2C] and 6.80[m, 16H,
C6H4]. IR (cmϪ1): 1613s, 1514s, 1347m, 1272w, 1221w, 1164m,
1142s, 947w, 920m, 852m, 810m, 795m and 677s. Found:
C, 66.7; H, 8.10, N, 8.6%. Calc. for C37H53InN4: C, 66.45; H,
8.00; N, 8.38%.
Single crystals of compounds 1–4 suitable for X-ray diffraction
were obtained by slow recrystallisation of each adduct from
toluene. Crystallographic data were recorded on a STOE-IPDS
diffractometer using graphite monochromated Mo-Kα radi-
ation (λ = 0.71073 Å), T = 200 K. Structures were solved by
Direct Methods and refined by full-matrix least squares against
F2 using all data.17 Crystal and data collection parameters are
given in Table 1.
2Me3InؒMBDA 2. Colourless crystalline solid. mp 79–80 ЊC.
1H NMR (C6D6, 300 MHz, 20 ЊC): δ Ϫ0.19[s, 18H, InCH3],
2.37[s, 12H, NCH3], 3.75[s, 2H, CCH2C] and 6.8[m, 8H, C6H4].
IR (cmϪ1): 1613s, 1514s, 1347m, 1272w, 1221w, 1164m, 1142s,
947w, 920m, 852m, 810m, 795m and 677s. Found: C, 47.77;
H, 7.07; N, 4.79%. Calc. for C23H40In2N2: C, 48.09; H, 7.03;
N, 4.88%.
CCDC reference number 186/2258.
See http://www.rsc.org/suppdata/dt/b0/b008600m/ for crys-
tallographic files in .cif format.
3 Results and discussion
Structures of Me3Inؒ2MBDA 1 and 2Me3InؒMBDA 2
4Me3InؒN4-aza crown 3. Colourless crystalline solid. mp
181–182 ЊC. H NMR (C6D6, 300 MHz, 20 ЊC): δ 0.00[s, 36H,
1
The crystal structures of compounds 1 and 2 are shown in
Figs. 2 and 3, whilst selected bond lengths and angles are given
in Table 2.
The structure of compound 1 is noteworthy in that the Me3In
moiety is five-coordinate with the longest In–N bond lengths
(2.720(4), 2.865(4) Å) reported to date. Only a few five-
coordinate alkylindium adducts have been reported, and these
InCH3], 1.25[quintet, 4H, CH2CH2CH2], 1.95[s, 4H, NCH3]
and 2.20[broad s, 16H, NCH2CH2CH2N, NCH2CH2N].
IR (cmϪ1): 2267w, 1608w, 1388m, 1329w, 1285w, 1215m, 1183m,
1148s, 1138m, 1089m, 1036s, 1027s, 1022m, 948w, 883w,
832w and 682s. Found: C, 34.73; H, 7.47; N, 5.80%. Calc. for
C13H34In2N2: C, 34.84; H, 7.66; N, 6.25%.
42
J. Chem. Soc., Dalton Trans., 2001, 41–45

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Table 2 Selected bond lengths (Å) and angles (Њ) for Me3Inؒ2MBDA 1
and 2Me3InؒMBDA 2
1
2
In(1)–C(3)
In(1)–C(1)
In(1)–C(2)
In(1)–N(1)
In(1)–N(3)
2.157(5)
2.164(5)
2.189(5)
2.720(4)
2.865(4)
In(1)–C(1)
In(1)–C(2)
In(1)–C(3)
In(2)–C(4)
In(2)–C(5)
In(2)–C(6)
In(1)–N(1)
In(2)–N(2)
2.167(4)
2.155(5)
2.172(4)
2.168(5)
2.165(5)
2.171(6)
2.446(3)
2.462(4)
C(3)–In(1)–C(1)
C(3)–In(1)–C(2)
C(2)–In(1)–C(2)
C(3)–In(1)–N(1)
C(1)–In(1)–N(1)
C(2)–In(1)–N(1)
C(3)–In(1)–N(3)
C(1)–In(1)–N(3)
C(2)–In(1)–N(3)
N(1)–In(1)–N(3)
121.1(2)
121.5(2)
117.3(2)
90.99(16)
90.82(16)
92.03(16)
89.51(16)
88.72(16)
87.91(16)
179.45(12)
C(2)–In(1)–C(3)
C(2)–In(1)–C(1)
C(3)–In(1)–C(1)
C(4)–In(2)–C(5)
C(4)–In(2)–C(6)
C(5)–In(2)–C(6)
N(1)–In(1)–C(1)
N(1)–In(1)–C(2)
N(1)–In(1)–C(3)
N(2)–In(2)–C(4)
N(2)–In(2)–C(5)
N(2)–In(2)–C(6)
120.17(19)
116.2(2)
116.35(18)
117.4(3)
118.5(2)
117.2(3)
101.42(14)
98.69(15)
97.07(14)
100.13(18)
97.0(2)
Fig. 4 Crystal structure of 4Me3InؒN4-aza crown 3.
99.26(18)
Fig. 3 Crystal structure of 2Me3InؒMBDA 2.
generally involve chelating donor ligands (e.g. Me3InؒMe2-
18
NCH2NMe2 and Me2InClؒ2,2Ј-bipy19) and structural data
are scarce. The In–N bond lengths are significantly greater
than those in the adducts Me3InؒNHCMe2(CH2)3CMe2 and
Me3InؒNHMe(CH2)2NHMeؒInMe3 which are 2.502(5) and
2.369(7) Å, respectively.7 In 1 the Me3In moiety is in a trigonal
bipyramidal configuration with a linear N–In–N bond angle of
179.45(12)Њ, similar to the Me3In configuration in the polymeric
complex [Me3InؒN(CH2CH2)3N]x, which also displays very
long In–N bond lengths (2.62 Å).7 The C–In–C bond angles in 1
of close to 120Њ are very close to those in pure unadducted
Me3In, in which the Me3In exists in the trigonal planar con-
figuration, providing further evidence of the very weak In–N
interactions in 1.
Fig. 5 Crystal structure of 6Me3InؒN6-aza crown 4.
Me3In and MBDA in solution. This may be similar to the case
of mixtures of Et3Ga and N6-aza crown in which two separate
species, 4Et3GaؒN6-aza crown and 6Et3GaؒN6-aza crown, were
isolated from the same solution and characterised by X-ray
diffraction.11
Structures of 4Me3InؒN4-aza crown 3 and 6Me3InؒN6-aza
crown 4
The long In–N bond lengths in five-coordinate trigonal
bipyramidal adducts such as 1 and [Me3Inؒ(NCH2CH2)3N]x
have been attributed7 to the In being sp3d hybridised (i.e. dona-
The crystal structures of compounds 3 and 4 are shown in
Figs. 4 and 5, respectively and selected bond distances and
angles are given in Table 3. Each adduct displays the expected
4:1 and 6:1 Me3In:ligand stoichiometries. In the case of 4
this contrasts with N6-aza crown complexes involving more
bulky R3Ga moieties, such as 4PriGaؒN6-aza crown where steric
constraints limit the stoichiometry at 4:1.11
2
tion of nitrogen lone pairs into a combination of 5pz and 5dz
orbitals on In). These will be weaker interactions than donation
into a single vacant sp3 hybrid orbital on In, as occurs in four-
coordinate Me3InؒL adducts.
In compound 2 the In–N lengths of 2.446(3) and 2.462(4) Å
are significantly shorter than in 1, indicating a stronger In–N
interaction. The Me3In is four-coordinate and exists in a
distorted tetrahedral environment with N–In–C bond angles
ranging from 97.0(2)Њ to 101.42(14)Њ, similar to those in
Me3InؒNHMe(CH2)2NHMeؒInMe3 (98.8(4)–101.4(3)Њ) and
In compounds 3 and 4 the Me3In molecules exhibit distorted
tetrahedral geometry, with C–In–N bond angles ranging from
95.6(6) to 104.2(5)Њ in 3 and 95.27(14)–101.85(17)Њ in 4,
significantly less than the tetrahedral angle of 109Њ. These are
entirely typical of C–In–N bond angles in tetrahedrally
coordinated Me3In adducts, as shown by the comparative data
for a range of Me3In–tertiary amine adducts given in Table 4.
The In–N bond lengths in 3 and 4 are close to the In–N bond
length in 2, and fairly typical for In–N bond lengths in an sp3
hybridised tetrahedral configuration (see Table 4). The In–N
bond lengths in 2, 3 and 4 are significantly shorter than the In–
N length in the sp3d hybridised complex 1. The In–N bond
distance in 4 is very slightly longer than that in 3, presumably
Me3InؒNHCMe2(CH2)3CMe2 (92.8(2)–109.3(2)Њ). The C–In–C
bond angles in 2 (≈116Њ) are similar to those in Me3Inؒ
NHMe(CH2)2NHMeؒInMe3 (≈116Њ) and Me3InؒNHCMe2-
(CH2)3CMe2 (≈117.6Њ),7 which also display comparable In–N
bond distances (2.37–2.50 Å).
The similarity in chemical shifts in the 1NMR data for 1 and
2 suggests that both compounds may be present in mixtures of
J. Chem. Soc., Dalton Trans., 2001, 41–45
43

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due to a slight increase in steric hindrance in the 6Me3InؒN6-aza
crown complex.
Me3In when heated at 80–130 ЊC in vacuo.4 Complexes 1, 3 and
4 were also found to liberate base-free Me3In (confirmed by
1H NMR spectroscopy) when heated at relatively low temper-
atures 80–115 ЊC under vacuum. A sample of crude Me3In
containing high levels of MeI (18000 ppm, deriving from the
Grignard-based synthesis route) was purified by thermal
dissociation of the adducts 1–4 and it was shown that, in each
case, the iodide impurity level was reduced to <10 ppm. Such
a dramatic reduction can be attributed to formation of
the involatile quaternary ammonium salt, R4NϩIϪ, resulting
from reaction between the tertiary amine and MeI.25 It has
previously been shown that MBDA is highly effective in
removing trace metal impurities (e.g. Si, Zn, Mg) from Me3In,4
but removal of the organic impurity MeI is a useful additional
advantage of tertiary amines in adduct purification processes.
The Me3Al and Me3Ga analogues to 2 have been structurally
characterised,13,14 and this allows us to make a direct com-
parison of M–N, M–C bond lengths, and various intra-
molecular angles in the R3M molecule (see Table 5). The most
notable feature is that the M–N adduct bond length decreases
in the order In > Ga > Al, in line with increasing Lewis acidity
of the metal centre.20 The M–C bond lengths show a similar
trend, decreasing in the order In > Ga ≈ Al, broadly consistent
with increasing strength of the metal–carbon bond. The M–C
bond lengths in the 4Me3GaؒN4-aza crown and 4Me3InؒN4-aza
crown adducts are close to those in the unadducted compounds,
Me3Ga(g) (M–C: 1.967(2) Å)21 and Me3In(s) (M–C: 2.16(4)–
2.25(6) Å).22,23 However, the Al–C bond lengths of 1.960(5)–
1.966(6) Å in 4Me3AlؒN4-aza crown are slightly shorter
than the terminal Al–C distances in the Me3Al dimer (1.99 Å).24
The C–M–N bond angle decreases in the order Al > Ga >
In, with an increasing deviation from the tetrahedral angle
of 109Њ.
4 Conclusion
The crystal structures of Me3Inؒ2MBDA 1, 2Me3InؒMBDA 2,
4Me3InؒN4-aza crown 3 and 6Me3InؒN6-aza crown 4 have been
determined. Compound 1 is one of only two reported adducts
containing five-coordinate Me3In, whereas 2–4 contain four-
coordinate Me3In in a distorted tetrahedral configuration. The
adducts 1–4 all liberate base-free Me3In at low/moderate
temperatures and are suitable for adduct purification of Me3In
for electronic applications.
Dissociation of Me3In–aza crown adducts
Complex 2 has previously been shown to liberate base free
Table 3 Selected bond lengths (Å) and angles (Њ) in 4Me3InؒN4-aza
crown 3 and 6Me3InؒN6-aza crown 4
3
4
Acknowledgements
In(1)–C(1)
In(1)–C(2)
In(1)–C(3)
In(2)–C(4)
In(2)–C(5)
In(2)–C(6)
In(1)–N(1)
In(2)–N(2)
2.169(16)
2.158(17)
2.175(16)
2.170(17)
2.162(18)
2.180(17)
2.433(12)
2.427(11)
In(1)–C(1)
In(1)–C(2)
In(1)–C(3)
In(2)–C(4)
In(2)–C(5)
In(2)–C(6)
In(1)–N(1)
In(2)–N(2)
In(3)–N(3)
2.166(4)
2.169(4)
2.170(5)
2.168(5)
2.166(5)
2.169(6)
2.490(3)
2.462(3)
2.449(3)
We are very grateful to Epichem Limited for funding the work
and for providing samples of Me3In. We also thank Mr
S. A. Apter (University of Liverpool, UK) for provision of the
microanalytical data.
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C(1)–In(1)–C(2)
C(1)–In(1)–C(3)
C(2)–In(1)–C(3)
C(6)–In(2)–C(5)
C(6)–In(2)–C(4)
C(4)–In(2)–C(5)
N(1)–In(1)–C(1)
N(1)–In(1)–C(2)
N(1)–In(1)–C(3)
N(2)–In(2)–C(4)
N(2)–In(2)–C(5)
N(2)–In(2)–C(6)
118.1(7)
121.3(7)
113.8(8)
120.8(8)
120.9(7)
111.7(8)
95.9(6)
104.2(5)
96.4(6)
101.1(5)
99.3(6)
C(1)–In(1)–C(2)
C(1)–In(1)–C(3)
C(2)–In(1)–C(3)
C(7)–In(3)–C(8)
C(7)–In(3)–C(9)
C(8)–In(3)–C(9)
N(1)–In(1)–C(1)
N(1)–In(1)–C(2)
N(1)–In(1)–C(3)
N(2)–In(2)–C(4)
N(2)–In(2)–C(5)
N(2)–In(2)–C(6)
118.7(2)
113.97(19)
122.16(18)
120.4(2)
119.5(2)
113.1(2)
99.79(15)
97.86(14)
95.27(14)
101.85(17)
100.44(15)
97.87(16)
95.6(6)
Table 4 Bond lengths (Å) and angles (Њ) for some Me3In–tertiary amine adducts
Compound
In–N
In–C
C–In–C
C–In–N
Reference
Me3Inؒ2MBDA 1
2.720(4), 2.865(4)
2.446(3), 2.462(4)
2.427(11)–2.433(12)
2.449(3)–2.490(3)
2.157(5)–2.189(5)
2.165(5)–2.172(4)
2.158(17)–2.180(17)
2.166(4)–2.170(5)
117.3(2)–121.5(2)
116.2(2)–120.17(19)
111.7(8)–121.3(7)
113.1(2)–122.6(18)
87.91(16)–92.03(16)
97.0(2)–101.42(14)
95.6(6)–104.2(5)
This work
This work
This work
This work
2Me3InؒMBDA 2
4Me3InؒN4-aza crown 3
6Me3InؒN6-aza crown 4
95.27(14)–103.13(16)
Me3InؒNHCMe2(CH2)3CMe2
Me3InؒNHMe(CH2)2NHMeؒ
InMe3
2.502(5)
2.369(7), 2.393(7)
2.170(5)–2.174(6)
2.147(10)–2.183(9)
109.3(3)–118.9(3)
113.0(4)–120.2(4)
92.8(2)–109.3(2)
96.3(3)–101.4(3)
7
7
[Me3InؒN(CH2CH2)3N]x
2.62
2.172(7)–2.176(5)
119.4(2)
—
7
Table 5 Bond lengths (Å) and angles (Њ) for Me3MؒN4-aza crown adducts (M = Al, Ga or In)
Compound
M–N
M–C
C–M–C
C–M–N
Reference
4Me3AlؒN4-aza crown
4Me3GaؒN4-aza crown
4Me3InؒN4-aza crown
2.093(3), 2.102(3)
2.182(4), 2.202(4)
2.433(12), 2.427(11)
1.960(5)–1.966(6)
1.970(6)–1.973(6)
2.158(17)–2.180(17)
—
102.8(2)–107.1(2)
101.0(2)–105.9(2)
95.6(6)–104.2(5)
13
14
113.0(3)–118.1(3)
111.7(8)–121.3(7)
This work
44
J. Chem. Soc., Dalton Trans., 2001, 41–45

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