Bulky amidinato complexes and amidine adducts of Al, Ga and In halides

Article abstract of DOI:10.1016/j.poly.2005.10.020

Reactions of a series of bulky amidinate salts M[RC(NAr)₂] (M = Li, Na or K; R = H, Fiso; Me, Aiso; Bu^t, Piso; Ar = 2, 6 - Pr₂ⁱ C₆ H₃) with group 13 halides are reported. Treatment of the metal(I) halides, 'GaI' or InCl, with [Li(Fiso)] led to disproportionation reactions which gave the first gallium(II)-amidinate complex, [{GaI(Fiso)}₂] (7), in addition to the metal(III) complexes, [GaI(Fiso)₂] (8) and [InCl(Fiso)₂] (10). Moreover, the Ga(II) compounds 7 and [{GaI(Piso)}₂] (9) were synthesised in metathesis reactions between amidinate salts and [{GaI₂(NHCy₂)}₂] (Cy=cyclohexyl). Treating [AlMe₂(Aiso)], [{AlH₂(Piso)}₂] or [AlMe₂(Piso)] with iodine in toluene led to isolation of the Al(III) iodide complexes [AlI₂(Aiso)] (12), [AlI₃(AisoH)] (13) and [AlI₂(Piso)] (14). The adduct [GaCl₃(FisoH)] (16) was obtained from the reactions of either [Na(Fiso)] or FisoH with GaCl₃, whilst the amidinium salt [TripH₂][InBr₄] (17), (Trip = [TrC(NPrⁱ)₂]^-, Tr = 9-triptycenyl) was isolated from the reaction of [Li(Trip)] with InBr₃. The X-ray crystal structures of 7, 9, 10, 13, 14, 16 and 17 are reported.

Full text of DOI:10.1016/j.poly.2005.10.020

Polyhedron 25 (2006) 1592–1600
www.elsevier.com/locate/poly
Bulky amidinato complexes and amidine adducts of
Al, Ga and In halides
a,
b,
a,b
Cameron Jones *, Peter C. Junk *, Marc Kloth
,
Kathryn M. Proctor a,b, Andreas Stasch
a,b
a
Centre for Fundamental and Applied Main Group Chemistry, School of Chemistry, Main Building, Cardiff University, Cardiff CF10 3AT, UK
b
School of Chemistry, Monash University, Melbourne, P.O. Box 23, Vic. 2800, Australia
Received 13 September 2005; accepted 25 October 2005
Available online 2 December 2005
Abstract
Reactions of a series of bulky amidinate salts M[RC(NAr)2] (M = Li, Na or K; R = H, Fiso; Me, Aiso; But, Piso; Ar ¼ 2; 6-Pri C6H3)
2
with group 13 halides are reported. Treatment of the metal(I) halides, ꢀGaIꢁ or InCl, with [Li(Fiso)] led to disproportionation reactions
which gave the first gallium(II)-amidinate complex, [{GaI(Fiso)}2] (7), in addition to the metal(III) complexes, [GaI(Fiso)2] (8) and
[InCl(Fiso)2] (10). Moreover, the Ga(II) compounds 7 and [{GaI(Piso)}2] (9) were synthesised in metathesis reactions between amidinate
salts and [{GaI2(NHCy2)}2] (Cy=cyclohexyl). Treating [AlMe2(Aiso)], [{AlH2(Piso)}2] or [AlMe2(Piso)] with iodine in toluene led to iso-
lation of the Al(III) iodide complexes [AlI2(Aiso)] (12), [AlI3(AisoH)] (13) and [AlI2(Piso)] (14). The adduct [GaCl3(FisoH)] (16) was
obtained from the reactions of either [Na(Fiso)] or FisoH with GaCl3, whilst the amidinium salt [TripH2][InBr4] (17),
(Trip = [TrC(NPri)2]ꢀ, Tr = 9-triptycenyl) was isolated from the reaction of [Li(Trip)] with InBr3. The X-ray crystal structures of 7,
9, 10, 13, 14, 16 and 17 are reported.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Aluminium; Amidinates; Gallium; Hydrides; Low oxidation state; N-Ligands; Indium
1. Introduction
ligands in the synthesis of thermally robust Al, Ga and
In hydride complexes, e.g., [MH(Fiso)2] (M = Al 1, Ga 2,
In 3) and [{AlH2(Piso)}2] (4) [3], in which the amidinate
chelates the metal centre, giving rise to four-membered
rings. We are also interested in utilising amidinates to sta-
bilise neutral group 13 metal(I) heterocycles, [M{j2-N,N-
N(R)C(R0)N(R)}], which can be considered as analogues
of four-membered N-heterocyclic carbenes. Although
unknown to date, these are closely related to neutral six-
membered heterocycles, e.g., [M{[N(Ar)C(Me)]2CH}]
(Ar ¼ C6H3Pri2-2; 6; M = Al, Ga, In or Tl) [4,5], which
are stabilised by bulky chelating b-diketiminate ligands.
We have had some success in this area with the isolation
of the first monomeric amidinato-indium(I) and thallium(I)
complexes, [{M(Piso)} Æ PisoH] (M = In 5, Tl 6) in which
the metal is ligated in an g1-N, g3-arene fashion [6].
Despite this experimental observation, DFT calculations
on a model compound, [In{N(Ph)C(H)N(Ph)}], suggest
The amidinate class of ligand has been extensively used
in recent decades to form a multitude of complexes with
main group, transition and lanthanide metals [1]. A wide
variety of coordination modes have been exhibited by the
amidinate ligands in these complexes. Of the main group
metal complexes, amidinato-group 13 species are especially
interesting, as amidinato-group 13 halide and alkyl deriva-
tives have found use in a number of applications, e.g., as
chemical vapour deposition precursors and as olefin poly-
merisation catalysts [2]. In this arena we have recently
employed bulky amidinates (see Fig. 1) as stabilising
*
Corresponding authors. Tel.: +44 0 29 20 874 060; fax: +44 0 29 20 874
030.
E-mail addresses: jonesca6@cf.ac.uk, jonesca6@cardiff.ac.uk (C.
Jones).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.10.020

C. Jones et al. / Polyhedron 25 (2006) 1592–1600
1593
PisoH. It is noteworthy that when the potassium salt
of the formamidinate, [K(Fiso)], was treated with
[{GaI2(NHCy2)}2] under similar conditions to the prepara-
tion of 7, only the gallium(III) complex, 8, was isolated in
moderate yield (Scheme 1).
In an attempt to form an indium(I)-amidinate complex,
[Li(Fiso)] was reacted with InCl in diethyl ether. This, how-
ever, led to indium metal deposition and the isolation of
[InCl(Fiso)2] (10) in moderate yield via a disproportion-
ation process (Scheme 2). It is worthy of note that similar
disproportionation reactions, but giving indium(II) com-
plexes, have been observed in the reactions of bulky lithium
b-diketiminates with InCl [9].
In the case of aluminium there is no known stable alu-
minium(I) halide that can be used as a precursor for
metathesis reactions. To circumvent this problem we
decided to synthesise suitable amidinato-aluminium(III)
iodide complexes and attempt their reduction to four-
membered aluminium(I) heterocycles. This seemed appro-
priate as six-membered aluminium(I) heterocycles have
previously been prepared by this methodology [4a]. There-
fore, we treated the known aluminium alkyl and hydride
complexes, [AlMe2(Aiso)] (11) [2c] and [{AlH2(Piso)}2]
(4) [3], with iodine in toluene (Scheme 3). In both cases
the expected complexes, 12 and 14, resulted, but the AlI3
adduct, 13, was also formed in the former reaction. Reac-
tion of [AlMe2(Piso)] (15) [2c] with I2 also yields 14, how-
ever the hydride route allows a faster reaction, a higher
yield and a cleaner product. Moreover, both iodine atoms
of the I2 reactant can be transferred to the Al centre
because the in situ formed HI subsequently reacts with
Ar
N
Fiso:
Aiso:
Piso:
Trip =
R = H
Ar =
R = Me
R = But
R
N
N
N
Pri
Ar
Pri
Fig. 1. Bulky amidinate ligands used in this study.
that its j2-N,N-chelated isomer is more stable than the g1-
N,g3-arene ligated form by 37.9 kJ/mol. In this paper we
detail further attempts to form complexes of the type,
[M{j2-N,N-N(R)C(R0)N(R)}]. Although unsuccessful,
these have led to the formation of a number of novel group
13-amidinate and amidine complexes.
2. Results and discussion
2.1. Syntheses
The synthesis of group 13 metal(I)-amidinate complexes
using metal halides as precursors could potentially be
achieved via two main routes, viz. metathesis reactions
between an amidinate salt and a low oxidation state metal
halide, or the reduction of a amidinato-metal(III) halide
complex. In the first instance, the treatment of ꢀGaIꢁ [7]
with an in situ prepared solution of the lithium formamidi-
nate, [Li(Fiso)], was carried at low temperature. Although
the a Ga(I)-amidinate complex did not result, colourless
crystals of an approximately 50:50 mixture of the gal-
lium(II) and (III) complexes, [{GaI(Fiso)}2] (7) and [GaI-
(Fiso)2] (8), were obtained (Scheme 1). The mechanism of
this reaction presumably involves a series of disproportion-
ation reactions, as evidenced by the deposition of gallium
metal. An intentional, moderately yielding synthesis of
the Ga(II) complex, 7, was devised whereby [Li(Fiso)]
was treated at low temperature in Et2O/toluene with the
Ga(II) halide complex, [{GaI2(NHCy2)}2] (Cy=cyclohexyl)
[8]. The related reaction of [{GaI2(NHCy2)}2] with the
bulkier pivamidinate salt, [Li(Piso)], afforded the analo-
gous dimeric complex, [{GaI(Piso)}2] (9), though only in
a trace yield. The only other products of the reaction that
were identifiable were gallium metal, LiI, NHCy2 and
Et2O
[InI(Fiso)2]
[Li(Fiso)]
InCl
-LiI, -In(s)
10
Scheme 2.
toluene
[AlMe2(Aiso)]
2 I2
[AlI3(AisoH)]
13
[AlI2(Aiso)]
-2MeI
11
12
toluene
-2H2
[{AlH2(Piso)}2]
2 I2
[AlI (Piso)]
2
2
4
14
Scheme 3.
toluene
[Li(Fiso)]
[{GaI(Fiso)}2]
[GaI(Fiso)2]
'GaI'
-LiI, -Ga(s)
8
7
Et2O / toluene
-LiI, -NHCy2
[{GaI2(NHCy2)}2]
[{GaI2(NHCy2)}2]
[Li(Fiso)]
[K(Fiso)]
[{GaI(Fiso)}2]
7
Et2O / toluene
[GaI(Fiso)2]
8
-KI, -NHCy2, -Ga(s)
Scheme 1.

1594
C. Jones et al. / Polyhedron 25 (2006) 1592–1600
Et2O
Et2O
THF
GaCl3
[GaCl3(FisoH)]
[Na(Fiso)]
+
+
+
16
[GaCl3(FisoH)]
GaCl3
InBr3
FisoH
16
[TripH2][InBr4]
[Li(Trip)]
17
Scheme 4.
another hydride ligand, while the initially formed MeI in
the alkyl route is less reactive and needs to be separated
from the reaction mixture. Unfortunately, all attempts to
reduce 12 or 14 to the corresponding aluminium(I) hetero-
cycles using potassium metal, KC8 or sodium have so far
met with failure.
A number of attempts were made to prepare amidinato-
gallium(III) and indium(III) halide complexes as it was
thought their reduction to metal(I) complexes would be
more facile than for their aluminium counterparts. Little
success has been had here as, for example, the only identi-
fiable product from the reaction of [Na(Fiso)] with GaCl3
was the adduct, 16, formed in low yield (Scheme 4).
Although not useful for reduction reactions, compound
16 was intentionally prepared in moderate to good yield
by treating FisoH with GaCl3 (Scheme 4). Similarly, when
the very bulky lithium amidinate, [Li(Trip)] [10], was trea-
ted with InBr3 and the reaction mixture recrystallised from
chloroform, the only crystalline product obtained was the
amidinium salt, 17 (Scheme 4). The protons of the cation
presumably originate from either residual moisture in the
reagents (InBr3 or reaction solvents), or hydrogen abstrac-
tion from chloroform. The latter seems more likely as 17
was formed when the reaction and work-up was repeated
under rigorous exclusion of moisture. Attempts to recrys-
tallise the reaction product from THF instead of chloro-
form did not lead to a crystalline product.
Fig. 2. Molecular structure of 7 (ORTEP, 50% thermal ellipsoids).
Hydrogen atoms have been omitted for clarity. Selected bond lengths (A)
˚
and angles (ꢁ): Ga1–Ga2 2.4304(10), Ga1–I1 2.5437(9), Ga2–I2 2.5396(9),
Ga1–N1 2.009(4), Ga1–N2 2.019(4), Ga2–N3 2.011(4), Ga2–N4 2.008(4),
C1–N1 1.313(6), C1–N2 1.316(6), C2–N3 1.331(6), C2–N4 1.322(6); N1–
Ga1–N2 66.36(15), N3–Ga2–N4 66.75(16), Ga2–Ga1–I1 119.48(3), Ga1-
Ga2-I2 121.19(3), N1–C1–N2 114.0(4), N3–C2–N4 112.9(4).
2.2. Crystal structures
The crystal structure of 7 contains one full dimeric mol-
ecule in the asymmetric unit which is depicted in Fig. 2.
Each of its gallium centres form essentially planar four-
membered rings with the chelating amidinate unit (Ga–N:
Fig. 3. Molecular structure of 9 (ORTEP, 50% thermal ellipsoids).
˚
Hydrogen atoms have been omitted for clarity. Selected bond lengths (A)
and angles (ꢁ): Ga1–Ga10 2.4521(15), Ga1–I1 2.5537(10), Ga1–N1
2.006(5), Ga1–N2 1.996(5), C1–N1 1.337(8), C1–N2 1.342(8); N1–Ga1–
N2 66.2(2), Ga1ꢁ–Ga1–I1 115.56(5), N1–C1–N2 109.3(6). Symmetry
˚
2.012 A average), and each is further coordinated by an
˚
iodine atom (Ga–I: 2.542 A average). The distorted tetra-
hedral environments of the gallium centres are completed
0
operation : ꢀx + 2, ꢀy, ꢀz + 1.
˚
by a Ga–Ga bond with a length of 2.4304(10) A, which is
in the normal range for Ga–Ga bonds in compounds of
the type [{LGaI}2] [11].1 The two N2CGa planes are
approximately parallel to each other and almost perpendic-
ular to the nearly planar Ga2I2 fragment. The structure of
compound 9 (Fig. 3) is similar to that of 7 but the molecule
sits on an inversion centre and thus only half a molecule
occupies the asymmetric unit. The bulkier substituent in
the backbone of the amidinate unit in 9 leads to a slightly
more acute NCN angle [109.3(6)ꢁ] compared with those of
7 [112.9(4)ꢁ and 114.0(4)ꢁ]. In both compounds, the C–N
bond lengths within their four-membered rings are indica-
tive of considerable delocalisation over the NCN
1
As determined from a survey of the Cambridge Crystallographic
Database, September, 2005.

C. Jones et al. / Polyhedron 25 (2006) 1592–1600
1595
fragments. It is noteworthy that compounds 7 and 9 repre-
sent the first examples of gallium(II) complexes bearing an
amidinate group, though Uhl et al. [12] have reported a
related gallium(II) complex bearing a 1,3-diphenyltriaze-
nido group which is isoelectronic to formamidinates.
Compounds 8 and 10 are isomorphous with the group 13
hydride complexes [MH(Fiso)2] 1–3 [3], and display similar
structural features to each other, though the quality of the
data for 8 is too poor to allow comment on its structure
here. The indium centre of 10 (Fig. 4) is five coordinate with
two chelating amidinate units and one Cl atom [In–Cl:
˚
2.3574(10) A] giving it a heavily distorted trigonal bipyra-
midal coordination geometry with N(3) and N(1) in apical
positions. As a result, these N-centres are significantly more
distant from In(1) than equatorial N(2) and N(4). In addi-
tion, there appears to be a lesser degree of delocalisation
over the amidinate backbones of 10 compared with those
of 7 and 9, as evidenced by the significantly different N–C
distances within each NCN fragment of the former. The
structural parameters of 10 compare well with those of
the only other structurally characterised bis(amidinato)
indium halide complex, [InCl{[N(Cy)]2CBut}2] [13].
Fig. 5. Molecular structure of 13 (ORTEP, 50% thermal ellipsoids).
˚
Hydrogen atoms have been omitted for clarity. Selected bond lengths (A)
and angles (ꢁ): Al1–I1 2.530(2), Al1–I2 2.531(2), Al1–I3 2.473(2), Al1–N1
1.935(6), C1–N1 1.327(9), C1–N2 1.306(9); I1–Al1–I3 111.41(9), I1–Al1–
I2 107.27(18), I2–Al1–I3 112.18(8), C1–N1–Al1 126.2(5), N1–C1–N2
120.0(6).
Both compounds 13 and 16 (Figs. 5 and 6, respectively)
are adducts of a neutral amidine with a group 13 trihalide.
The main difference between their structures is the configu-
ration at the C(1)–N(1) bond which is Z for 13 and E for
16. This difference most likely results from the greater steric
influence of the methyl group on C(1) in 13 compared to
Fig. 6. Molecular structure of 16 (ORTEP, 50% thermal ellipsoids).
Hydrogen atoms, except on N(2), have been omitted for clarity. Selected
˚
bond lengths (A) and angles (ꢁ): Ga1–N1 1.941(3), Ga1–Cl1 2.1397(11),
Ga1–Cl2 2.1683(14), Ga1–Cl3 2.1676(13), C1–N1 1.306(4), C1–N2
1.309(4); Cl1–Ga1–Cl2 114.75(5), Cl1–Ga1–Cl3 114.57(4), Cl2–Ga1–Cl3
107.29(6), C1–N1–Ga1 116.1(2), N1–C1–N2 128.6(3).
Fig. 4. Molecular structure of 10 (ORTEP, 50% thermal ellipsoids).
Hydrogen atoms have been omitted for clarity. Selected bond lengths (A)
the hydrogen at C(1) in 16. The NCNM fragments of both
13 and 16 are essentially planar and the M–N bond lengths
[13 1.935(6) A, 16 1.941(3) A] are in the normal range, as
are the metal–halide distances.1 Surprisingly, an examina-
tion of the C–N distances within the NCN fragment of
16 suggests significant delocalisation over that fragment,
˚
and angles (ꢁ): In1–Cl1 2.3574(11), In1–N1 2.244(3), In1–N2 2.181(3),
In1–N3 2.270(3), In1–N4 2.168(3), C1–N1 1.309(5), C1–N2 1.327(5), C2–
N3 1.304(5), C2–N4 1.326(5); N1–In1–N2 60.30(11), N3–In1–N4
60.35(11), N2–In1–N3 105.72(11), N1–In1–N4 109.18(11), N1–In1–Cl1
101.45(8), N1–C1–N2 115.0(4), N3–C2–N4 116.1(3).
˚
˚

1596
C. Jones et al. / Polyhedron 25 (2006) 1592–1600
whereas the same fragment in 13 appears to be more
localised, though both its amidine N–C bond lengths lie
between those expected for single and double bonded
distances.1
The molecular structure of 14 is depicted in Fig. 7 and is
comparable with that of the corresponding methyl deriva-
tive [AlMe2(Piso)] (15) [2c] in that its metal centre is che-
lated by the Piso ligand and has a distorted tetrahedral
˚
˚
geometry. Its Al–N (1.886 A average) and Al–I (2.460 A
average) distances lie in the expected regions1. The struc-
ture of the amidinium salt, 17, (Fig. 8) shows the com-
pound to consist of separate ions which have no
significant contacts. The tetrahedral [InBr4]ꢀ anion has
been structurally characterised in salts on previous occa-
sions [14]. The geometry of the amidinium cation closely
resembles that of the neutral amidine [10], though the ami-
dine exhibits largely localised backbone NC bonds,
whereas those in 17 appear to be delocalised. In addition,
the amidinium cation has a slightly more acute NCN angle
[127.0(4)ꢁ] relative to that of the amidine, TripH
[129.91(18)ꢁ].
Fig. 8. Molecular structure of 17 (ORTEP, 50% thermal ellipsoids).
Hydrogen atoms, except on nitrogen atoms, have been omitted for clarity.
˚
Selected bond lengths (A) and angles (ꢁ): In1–Br1 2.5043(7), In1–Br2
2.5096(6), In1–Br3 2.4945(7), In1–Br4 2.4934(6), C2–N1 1.316(6), C2–N2
1.322(6); Br1–In1–Br2 105.20(2), Br3–In1–Br1 111.73(2), N1–C2–N2
127.0(4).
1
guished by their H NMR spectra. As expected, the spec-
trum of the higher symmetry compound, 12, shows two
isopropyl methyl doublet signals and one methine virtual
septet resonance, while the spectrum of 13 displays four
isopropyl methyl doublets and two methine septets. Con-
2.3. Spectroscopic properties
The NMR spectra for the majority of the compounds
reported here are consistent with their solid-state structures
and will be only briefly discussed. For example, the H
1
trastingly, both the H and 13C NMR spectra of [GaCl3-
1
(FisoH)] (16) are indicative of a more symmetrical molecule
than the solid-state structure suggests. This observation
implies a fluxional exchange of the GaCl3 fragment and
amidine proton between N-centres, which is rapid on the
NMR timescale. Cooling solutions of 16 did not lead to
a resolution of the spectra. The NH proton of 13 resonates
at d 8.98 ppm (IR: N–H stretch 3295 cmꢀ1) and that for 16
appears at d 8.67 ppm (IR: N–H stretch 3313 cmꢀ1), cf. 17
1H NMR: d 5.42 ppm (NH); IR: 3358 cmꢀ1 (N–H str.).
NMR spectrum of [{GaI(Fiso)}2] (7) displays two methyl
doublet resonances and a virtual septet for the methine
protons. The 1H NMR spectra for the compounds
[MX(Fiso)2] (8: M = Ga, X = I; 10: M = In, X = Cl) are
less symmetrical and exhibit overlapping multiplet reso-
nances for the protons of the methyl groups. Compounds
[AlI2(Aiso)] (12) and [AlI3(AisoH)] (13) can be easily distin-
3. Conclusions
Attempts have been made to synthesise amidinato-
group 13 metal(I) complexes, either by methathesis reac-
tions between amidinate salts and metal(I) halides, or by
reduction of amidinato-metal(III) halide complexes.
Although no metal(I) complexes have been formed, the for-
mer route has led to a range of amidinato-metal(II) and
(III) complexes via disproportionation processes. These
include the first examples of gallium(II) amidinate com-
plexes. Metathesis reactions between amidinate salts and
metal(III) halides have afforded a series of amidinato-meta-
l(III) halide complexes, amidine-metal(III) halide adducts
and one amidinium salt. In general, and like our previous
findings with amidinato-group 13 hydride complexes [3b],
syntheses employing the Fiso ligand normally lead to com-
plexes bearing two amidinate ligands (except the Ga(II)
compound 7), whereas only one Piso group could be trans-
ferred to a metal atom. This is probably because the bulky
But group on the backbone of Piso, compared to the
Fig. 7. Molecular structure of 14 (ORTEP, 50% thermal ellipsoids).
˚
Hydrogen atoms have been omitted for clarity. Selected bond lengths (A)
and angles (ꢁ): Al1–N1 1.884(7), Al1–N2 1.889(8), Al1–I1 2.481(3), Al1–I2
2.438(3), C1–N1 1.363(12), C1–N2 1.350(11); I1–Al1–I2 107.21(11), N1–
Al1–N2 70.3(3), N1–C1–N2 106.4(7).

C. Jones et al. / Polyhedron 25 (2006) 1592–1600
1597
hydrogen backbone atom of Fiso, gives a more rigid and
sterically demanding amidinate unit. Further investigations
using bulky amidinate and related ligands to stabilise low
oxidation state group 13 complexes by metathesis or reduc-
tion pathways are underway in our laboratory.
(d, 3JHH = 6.8 Hz, 24 H, CH(CH3)), 1.48 (d,
3JHH = 6.8 Hz, 24 H, CH(CH3)), 3.92 (v. sept,
3JHH = 6.8 Hz, 8 H, CH(CH3)), 7.10–7.30 (m, 12 H, Ar–
H), 7.55 (s, 2H, NC(H)N); 13C NMR (100.6 MHz, C6D6,
298 K):
d
25.0 (CH(CH3)), 26.0 (CH(CH3)), 29.2
(CH(CH3)), 124.4 (m-ArC), 127.4 (p-ArC), 138.0 (ipso-
ArC), 145.4 (o-ArC), 166.6 (NCN); MS/EI, m/z (%):
365.3 (FisoH+, 12), 176.0 (ArNH+, 100); IR m/cmꢀ1
(Nujol): 1668 m, 1636 m, 1585 m, 1260 s, 1097 m, 1055
m, 933 m, 799 m, 753 m. N.B. [{GaI(Piso)}2] (9) was pre-
pared by an equivalent procedure but was only obtained
in trace amounts. As a result, no spectroscopic data were
obtained for this compound.
4. Experimental
4.1. General
All manipulations were carried out using standard
Schlenk line and glove box techniques under an inert
atmosphere (argon or nitrogen). Hexane, toluene, THF
and D6-benzene were distilled over potassium, whilst
diethyl ether was distilled over Na/K alloy. Infrared
spectra were obtained as Nujol mulls using a Perkin–
Elmer 1600 Series FTIR spectrometer with NaCl plates.
NMR spectroscopy was carried out using either Jeol
Eclipse 300, Bruker WM 250 or Bruker DPX 400 spec-
trometers, and were referenced to the residual 1H or
13C resonances of the solvent used. Mass spectra were
recorded using a VG Fisons Platform II instrument oper-
ating under APCI conditions, or were obtained from the
EPSRC Mass Spectrometry Service, Swansea. Melting
points were obtained under argon in sealed capillaries
and are not corrected. The compounds FisoH [15], PisoH
[16], ꢀGaIꢁ [17] and [AlMe2(Aiso)] [2c] were synthesised
by literature procedures. [K(Piso)] 2 was obtained by
treating PisoH with 1.05 eq. of K[N(SiMe3)2] in toluene
(reflux, 2 h), then removing all volatiles in vacuo and
drying the residue at 50 ꢁC under vacuum for several
hours. [AlMe2(Piso)] was synthesised by treatment of
PisoH with 1.05 eq of AlMe3 in toluene (ꢀ78 ꢁC to room
temperature), removing all volatiles and drying the prod-
uct under vacuum. The product was obtained almost
quantitatively as a colourless crystalline material and
the spectroscopic data were compared with the literature
values [2c].
4.3. [GaI(Fiso)2] (8)
A solution of [{GaI2(NHCy2)}2] (0.88 g, 0.87 mmol) in
toluene (20 mL) and Et2O (10 mL) was added at ꢀ80 ꢁC
to a slurry of [K(Fiso)] (0.77 g, 1.91 mmol) in toluene
(20 mL) and Et2O (10 mL). The mixture was warmed to
room temperature overnight, filtered, concentrated to ca.
30 mL and placed at ꢀ30 ꢁC overnight to yield colourless
crystals of 8. Yield: 0.33 g, 41%; m.p. 275–277 ꢁC; 1H
NMR (400 MHz, C6D6, 298 K): d 1.10–1.35 (m, 48 H,
3
CH(CH3)2), 3.54 (br. v. sept, JHH = ca. 6.7 Hz, 8 H,
CH(CH3)2), 6.97–7.30 (m, 12 H, Ar–H), 7.63 (s, 2 H,
NCHN);13C NMR (100.6 MHz, C6D6, 298 K): d 23.8
(CH(CH3)), 24.5 (CH(CH3)), 25.1 (CH(CH3)), 25.5
(CH(CH3)), 28.5 (CH(CH3)), 28.6 (CH(CH3)), 123.4 (m-
ArC), 125.6 (p-ArC), 141.2 (ipso-ArC), 144.0 (o-ArC),
160.2 (NCN); MS/APCI m/z (%): 365 ðFisoHþ2 ; 100Þ; IR
m/cmꢀ1 (Nujol): 1668 m, 1560 m, 1260 s, 1200 m, 1176 m,
799 m, 751 m.
4.4. [InCl(Fiso)2] (10)
BunLi (2.50 ml of
a 1.6 M solution in hexanes,
4.00 mmol) was added at room temperature to a solution
of FisoH (1.39 g, 3.80 mmol) in Et2O (70 mL) and the
mixture stirred for 3 h. The resultant solution was added
dropwise at to a slurry of InCl (1.20 g, 7.99 mmol) in
Et2O (20 mL) at ꢀ80 ꢁC. The reaction mixture was slowly
warmed to room temperature overnight in the absence of
light. It was then filtered, volatiles removed from the fil-
trate in vacuo and the residue was extracted into hexane
(40 mL). Placement of the extract at ꢀ30 ꢁC overnight
gave colourless crystals of 10. Yield 0.42 g, 25%; m.p.
4.2. [{GaI(Fiso)}2] (7)
BunLi (0.743 ml of a 1.6 M solution in hexanes,
1.19 mmol) was added to solution of FisoH (0.433 g,
1.19 mmol) in diethyl ether (30 mL) at ꢀ20 ꢁC. The resul-
tant solution was warmed to room temperature and stirred
overnight. It was then cooled to ꢀ50 ꢁC and a solution of
[{GaI2(NHCy2)}2] (0.60 g, 0.59 mmol) in toluene (30 mL)
added over 5 min. The resultant solution was stirred for
2 h and slowly warmed to room temperature overnight.
Volatiles were then removed in vacuo and the residue
was extracted into hexane (50 mL) and filtered. The filtrate
was concentrated to ca. 30 mL and placed at ꢀ30 ꢁC over-
night giving colourless crystals of 7. Yield: 0.30 g, 42%;
1
200–205 ꢁC (dec.); H NMR (400 MHz, C6D6, 298 K): d
1.00–1.80 (m, 48 H, CH(CH3)2), 3.71–4.00 (m, 8 H,
CH(CH3)2), 6.90–7.28 (m, 12 H, Ar–H), 7.47 (s, 2 H,
NC(H)N); 13C NMR (100.6 MHz, C6D6, 298 K): d 24.0
(CH(CH3)), 24.5 (CH(CH3)), 25.3 (CH(CH3)), 25.5
(CH(CH3)), 28.3 (CH(CH3)), 28.6 (CH(CH3)), 123.5 (m-
ArC), 126.3 (p-ArC), 139.3 (ipso-ArC), 143.6, (o-ArC),
158.1 (NCN); MS/APCI, m/z (%): 365 ðFisoHþ2 ; 100Þ;
IR m/cmꢀ1 (Nujol): 1668 m, 1636, 1585 m, 1260 s, 1097
m, 1055 m, 933 m, 799 m.
1
m.p. >300 ꢁC; H NMR (250 MHz, C6D6, 298 K): d 1.20
2
THF adducts of [K(Piso)] have been previously obtained, see [15].

1598
C. Jones et al. / Polyhedron 25 (2006) 1592–1600
3
4.5. [AlI2(Aiso)] (12) and [AlI3(AisoH)] (13)
12 H, CH3), 1.48 (d, JHH = 6.8 Hz, 12 H, CH3), 3.83 (v.
3
sept, JHH = 6.8 Hz, 4 H, CH), 7.06–7.26 (m, 6 H, Ar–
A solution of I2 (3.85 g, 15.2 mmol) in toluene was
added to a cooled solution (ꢀ80 ꢁC) of [AlMe2(Aiso)]
(3.00 g, 6.90 mmol, 1.0 eq) in toluene (35 mL). The mixture
was then warmed to room temperature and stirred for 2 d.
Volatiles were removed in vacuo, the residue extracted with
hexane (40 mL) and the extract placed at ꢀ30 ꢁC overnight
to give yellow crystals of 13. Volatiles were removed from
the mother liquor and the residue dissolved in toluene/hex-
ane (2:1, 60 mL) and placed at ꢀ30ꢁC overnight to give
crystals of 13 in a first crop and a mixture of 12 and 13
in a second crop. The crystals were manually separated.
12: Yield 0.74 g, 16%; m.p. 186–187 ꢁC; 1H NMR
H), 13C NMR (100.6 MHz, C6D6, 298 K):
d 21.8
(CH(CH3)), 28.0 (CH(CH3)), 28.3 (CH(CH3)), 28.7
(C(CH3)3), 41.2 (C(CH3)3), 123.2 (m-ArC), 129.2 (p-ArC),
135.0 (ipso-ArC), 144.1 (o-ArC), 185.9 (NCN); MS/APCI
m/z (%): 421 (PisoH+, 100), 244 (PisoH+ ꢀ ArNH, 71);
IR m/cmꢀ1 (Nujol): 1641 m, 1590 m, 1542 m, 1323 m,
1257 s, 1200 m, 1178 m, 1098 m, 803 m, 756 m.
4.7. [GaCl3(FisoH)] (16)
A solution of FisoH (0.50 g, 1.37 mmol) in Et2O
(20 mL) was added to a solution of GaCl3 (0.25 g,
1.37 mmol) in Et2O (10 mL) at ꢀ80 ꢁC. The mixture was
slowly warmed to room temperature, filtered and the sol-
vent removed in vacuo. The residue was extracted into tol-
uene (8 mL) and the extract cooled to ꢀ30 ꢁC to give
colourless crystals of 16. Yield 0.48 g, 65%; m.p. 158–
3
(400 MHz, C6D6, 298 K): d 1.02 (d, JHH = 6.8 Hz, 12 H,
3
CH(CH3)), 1.17 (s, 3 H, CCH3), 1.19 (d, JHH = 6.8 Hz,
3
12 H, CH(CH3)), 3.50 (v. sept, JHH = 6.8 Hz, 4 H,
CH(CH3)), 6.82–7.08 (m,
(100.6 MHz, C6D6, 298 K):
6
H, Ar–H); 13C NMR
d
14.5 (H3CC), 24.3
1
(CH(CH3)), 25.8 (CH(CH3)), 28.9 (CH(CH3)), 124.6 (m-
ArC), 129.2 (p-ArC), 135.1 (ipso-ArC), 145.4 (o-ArC),
172.0 (NCN); MS/EI m/z (%): 378.3 (AisoH+, 22), 335.3
(AisoH+ ꢀ Pri, 26), 202.2 (AisoH+ ꢀ ArNH, 100), 177.2
ðArNH2þ; 24Þ; IR m/cmꢀ1 (Nujol): 1636 m, 1596 m, 1260
s, 1097 m, 934 m, 864 m, 799 m, 746 m.
160 ꢁC; H NMR (300 MHz, C6D6, 298 K): d 1.13 (br. d,
3JHH = 6.8 Hz, 24 H, CH(CH3)), 3.27 (br. sept,
3JHH = 6.8 Hz, 4 H, CH(CH3)), 7.02–7.09 (m, 6 H, Ar–
H), 7.83 (s, 1 H, HCN2), 8.67 (s, 1 H, NH); 13C NMR
(100.6 MHz, C6D6, 298 K): d 22.5 (CH(CH3)), 27.3
(CH(CH3)), 122.6 (m-ArC), 122.9 (p-ArC), 124.9 (ipso-
ArC), 127.5 (o-ArC), 146.6 (NCN); MS (APCI), m/z (%):
365 ðFisoH2þ; 100Þ; IR m/cmꢀ1 (Nujol): 3313 (NH), 1586
m, 1327 m, 1175 m, 1058 m, 806 m.
13: Yield 1.20 g, 22%; m.p. 220–222 ꢁC (dec.); 1H NMR
3
(400 MHz, C6D6, 298 K): d 1.10 (d, JHH = 6.8 Hz, 6 H,
3
CH(CH3)), 1.13 (d, JHH = 6.8 Hz, 6 H, CH(CH3)), 1.22
3
(d, JHH = 6.8 Hz, 6 H, CH(CH3)), 1.34 (s, 3 H, CCH3),
3
1.60 (d, JHH = 6.8 Hz, 6 H, CH(CH3)), 3.54 (v. sept,
4.8. [TripH2][InBr4] (17)
3JHH = 6.8 Hz,
2
H, CH(CH3)), 3.63 (v. sept,
3JHH = 6.8 Hz, 2 H, CH(CH3)), 7.00–7.24 (m, 6 H, Ar–
H), 8.98 (s, 1 H, NH); 13C NMR (100.6 MHz, C6D6,
298 K): d 14.5 (H3CC), 24.6 (CH(CH3)), 24.8 (CH(CH3)),
24.9 (CH(CH3)), 25.1 (CH(CH3)), 29.0 (CH(CH3)), 29.1
(CH(CH3)), 125.3 (m-ArC), 129.3 (p-ArC), 139.0 (ipso-
ArC), 144.8 (o-ArC), 186.0 (NCN); MS/EI m/z (%):
785.7 (M+, <5), 742.7 (M+ ꢀ Pri, <5), 659.0 (M+ ꢀ I,
100), 379.3 ðAisoH2þ; 19Þ, 335.2 (AisoH+ ꢀ Pri, 26),
202.2 (AisoH+ ꢀ ArNH, 100); IR m/cmꢀ1 (Nujol): 3295
(NH), 1641 m, 1570 m, 1321 m, 1260 s, 1170 m, 1096 m,
934 m, 870 m; Acc. mass. EI for M+ ꢀ I: found:
659.0926; calculated: 659.0934.
A solution of [Li(Trip)] (0.25 g, 65 mmol) in THF
(15 mL) was added over 5 min to a solution of InBr3
(0.23 g, 0.65 mmol) in THF (10 mL) at ꢀ50ꢁC. The mixture
was slowly warmed to room temperature and stirred for
2 d. Volatiles were removed in vacuo and the residue
washed with hexane (20 mL) and Et2O (15 mL). The resi-
due was then recrystallised from chloroform at ꢀ30 ꢁC giv-
ing colourless crystals of 17 overnight. Yield 0.09 g, 15%;
1
m.p. 233–235 ꢁC; H NMR (300 MHz, CDCl3, 298 K): d
3
1.37 (d, JHH = 6.8 Hz,
6
H, CH(CH3)2), 1.65 (d,
3JHH = 6.8 Hz,
6
H, CH(CH3)2), 3.42 (v. sept,
3JHH = 6.8 Hz, 2 H, CH(CH3)2), 3.55 (s, 1 H, CH), 5.42
(s, 2 H, NH), 6.97–7.18 (m, 3 H, ArH), 7.22–7.29 (m, 3
H, ArH), 7.33–7.43 (m, 3 H, ArH), 7.52–7.68 (m, 3 H,
ArH); 13C NMR (100.6 MHz, C6D6, 298 K): d 22.1
(CH(CH3)), 23.4 (CH(CH3)), 24.7 (CH(CH3)), 50.6
(CAr3), 121.3 (ArC), 125.7 (ArC), 125.9 (ArC), 126.6
(ArC), 127.8 (ArC), 140.2 (ArC), 146.0 (NCN); MS/APCI
m/z (%): 381 ðTripH2þ; 100Þ; IR m/cmꢀ1 (Nujol): 3358
(NH), 1640 m, 1457 m, 1376 m, 1260 s, 1093 m, 911 m,
801 m, 750 m.
4.6. [AlI2(Piso)] (14)
A solution of I2 (0.54 g, 2.13 mmol) in toluene (30 mL)
was added dropwise to a slurry of [{AlH2(Piso)}2]
(0.91 g, 1.02 mmol) in toluene (15 mL) at ꢀ20 ꢁC until
gas evolution had ceased. The solution was then warmed
to room temperature and stirred for 30 min. Volatiles were
removed in vacuo and the residue dissolved in toluene
(30 mL), filtered and concentrated under reduced pressure
to give 14 as a light yellow crystalline solid after placement
at ꢀ30ꢁC overnight. Yield 1.25 g, 88%; m.p. 238–240 ꢁC
(no dec. until >300 ꢁC); 1H NMR (400 MHz, C6D6,
4.9. Crystallographic studies
Crystals of 7, 9, 10, 13, 14, 16 and 17 suitable for
X-ray crystal structure determination were mounted in
3
298 K): d 0.94 (s, 9 H, C(CH3)3), 1.39 (d, JHH = 6.8 Hz,

Table 1
Crystal data and refinement details for 7, 9, 10, 13, 16 and 17.CHCl3
Compound
7
9
10
13
14
16
17 Æ CHCl3
Formula
C50H70Ga2I2N4
1120.34
triclinic
C58H86Ga2I2N4
1232.55
orthorhombic
colourless block
0.25 · 0.25 · 0.20
Pbca
C50H70ClInN4
877.37
monoclinic
colourless plate
0.40 · 0.10 · 0.06
P21/c
14.490(3)
16.575(3)
21.288(4)
90
109.28(3)
90
C26H38AlI3N2
786.26
monoclinic
yellow block
0.10 · 0.10 · 0.10
P21/n
11.697(2)
19.694(4)
13.437(3)
90
92.39(3)
90
C29H43AlI2N2
700.43
orthorhombic
yellow block
0.15 · 0.15 · 0.10
Pna21
18.034(4)
10.165(2)
16.981(3)
90
C25H36Cl3GaN2
540.63
monoclinic
colourless block
0.10 · 0.10 · 0.10
P21/c
10.434(2)
19.992(4)
14.054(3)
90
108.53(3)
90
C28H30Br4Cl3InN2
935.35
triclinic
Molecular weight
Crystal system
Colour, habit
Crystal size/mm
Space group
colourless needle
0.12 · 0.06 · 0.04
colourless needle
0.10 · 0.03 · 0.03
ꢀ
ꢀ
P1
P1
˚
a (A)
10.782(2)
11.471(2)
21.861(4)
79.37(3)
83.10(3)
74.18(3)
2549.7(9)
2
14.479(3)
19.212(4)
20.302(4)
90
90
90
8.2810(2)
13.2880(4)
15.6340(5)
89.5200(10)
75.8270(10)
85.8670(10)
1663.55(8)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
3
˚
V (A )
5647(2)
4
4826.3(17)
4
3092.7(11)
4
3113.1(11)
4
2779.6(10)
4
Z
T (K)
150
1.459
2.303
1132
150
1.450
2.087
2520
150
1.207
0.581
1856
150
1.689
3.076
1520
150
1.494
2.067
1400
123
1.292
1.293
1128
150
1.867
5.776
904
qcalc (Mg mꢀ3
)
l (mmꢀ1
F(000)
)
H (ꢁ) for data
collection
3.04–27.47
2.92–27.50
3.00–27.47
3.03–26.37
3.02–26.00
2.95–25.02
3.08–25.00
Completeness
to h (%)
99.1
99.7
99.7
99.6
99.6
99.2
98.4
Reflections
collected/unique
Rint
44851/11551
40722/6470
34974/11026
21192/6317
20063/5188
13527/4873
9750/5770
0.1437
1.019
0.1167
1.011
0.1097
1.015
0.0760
1.039
0.1208
1.038
0.0685
1.055
0.0369
1.034
Goodness-of-fit
on F2
Parameters varied
540
310
533
299
319
296
356
Largest peak/hole
0.63/ꢀ0.89
0.63/ꢀ0.69
0.53/ꢀ0.71
1.96 (near I1)/ꢀ2.26
1.66 (near I1)/ꢀ1.59
0.99/ꢀ0.91
0.65/ꢀ0.83
3
(eꢀ1/A )
˚
(near I3)
(near I1)
Final R indices
[I > 2r(I)]
R1 = 0.0563,
wR2 = 0.0950
P
R1 = 0.0715,
wR2 = 0.1026
R1 = 0.0626,
wR2 = 0.1011
2
R1 = 0.0571,
wR2 = 0.1439
R1 = 0.0670,
wR2 = 0.1599
R1 = 0.0483, wR2 = 0.0993
R1 = 0.0382,
wR2 = 0.0774
P
P
P
R1(F) = { (|Fo|ꢀ|Fc|)/ |Fo|}. wR2ðF 2Þ ¼ f wðjF oj ꢀ jF cj Þ = wjF 2oj g1=2, where w is the weight given each reflection.
2
2 2

1600
C. Jones et al. / Polyhedron 25 (2006) 1592–1600
(d) S. Dagorne, R.F. Jordan, V.G. Young, Organometallics 18 (1999)
4619;
(e) G. Talarico, P.H.M. Budzelaar, Organometallics 19 (2000)
5691;
(f) S. Dagorne, I.A. Guzei, M.P. Coles, R.F. Jordan, J. Am. Chem.
Soc. 122 (2000) 274;
(g) D. Abeysekera, K.N. Robertson, T.S. Cameron, J.A.C. Clyburne,
Organometallics 20 (2001) 5532;
silicone oil. Crystallographic measurements were made
using a Nonius Kappa CCD diffractometer. The struc-
tures were solved by direct methods and refined on F2
by full matrix least squares (SHELX-97) [18] using all
unique data. Data were corrected for absorption using
a SORTAV multi-scan absorption correction [19]. The
Rint values for several of the compounds were high due
to poor crystal quality, though this has not led to any
ambiguity regarding the molecular connectivity of these
compounds. The Flack parameter of ꢀ0.05(5) for 14
confirms that it has been refined as its correct absolute
configuration. Crystal data, details of data collections
and refinement are given in Table 1.
(h) H.A. Jenkins, D. Abeysekera, D.A. Dickie, J.A.C. Clyburne,
Dalton Trans. (2002) 3919;
(i) J.A.R. Schmidt, J. Arnold, Organometallics 21 (2002) 2306;
(j) R.T. Boere, M.L. Cole, P.C. Junk, New. J. Chem. 29 (2005) 128.
[3] (a) R.J. Baker, C. Jones, P.C. Junk, M. Kloth, Angew. Chem. Int.
Ed. 43 (2004) 3852;
(b) M.L. Cole, C. Jones, P.C. Junk, M. Kloth, A. Stasch, Chem. Eur.
J. 11 (2005) 4482.
[4] (a) C. Cui, H.W. Roesky, H.-G. Schmidt, M. Noltemeyer, H. Hao,
F. Cimpoesu, Angew. Chem. Int. Ed. 29 (2000) 4274;
(b) N.J. Hardman, B.E. Eichler, P.P. Power, Chem. Commun. (2000)
1991;
5. Supplementary material
Crystallographic data (excluding structure factors) have
been deposited with the Cambridge Crystallographic Data
Centre. CCDC-283677 (7), CCDC-283672 (9), CCDC-
283678 (10), CCDC-283673 (13), CCDC-283674 (14),
CCDC-283675 (16) and CCDC-283676 (17) contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge via www.ccdc.cam.
ac.uk/conts/reteiving.html (or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge,
CB2 1EZ, UK; fax: +44 1223 336033; e-mail: depos-
it@ccdc. cam.ac.uk).
(c) M.S. Hill, P.B. Hitchcock, Chem. Commun. (2004) 1818;
(d) M.S. Hill, P.B. Hitchcock, R. Pongtavornpinyo, Dalton Trans.
(2005) 273;
(e) Y. Cheng, P.B. Hitchcock, M.F. Lappert, M. Zhou, Chem.
Commun. (2005) 752;
(f) M.S. Hill, P.B. Hitchcock, R. Pongtavornpinyo, Angew. Chem.
Int. Ed. 44 (2005) 4231.
[5] R.J. Baker, C. Jones, Coord. Chem. Rev. 249 (2005) 1857, and
references therein.
[6] C. Jones, P.C. Junk, J.A. Platts, D. Rathmann, A. Stasch, Dalton
Trans. (2005) 2497.
[7] R.J. Baker, C. Jones, Dalton Trans. (2005) 1341, and references
therein.
[8] R.J. Baker, H. Bettentrup, C. Jones, Eur. J. Inorg. Chem. (2003)
2446.
Acknowledgements
[9] M. Stender, P.P. Power, Polyhedron 21 (2002) 525.
[10] R.J. Baker, C. Jones, J. Organomet. Chem. (in press).
[11] (a) For example, R.J. Baker, R.D. Farley, C. Jones, M. Kloth, D.M.
Murphy, Dalton Trans. (2002) 3844;
We thank The Leverhulme Trust for funding (postdoc-
toral fellowship for A.S.) and the EPSRC (partial student-
ship for M.K.). The EPSRC National Mass Spectrometry
Service at Swansea University is also gratefully
acknowledged.
(b) N.J. Hardman, R.J. Wright, A.D. Phillips, P.P. Power, J. Am.
Chem. Soc. 125 (2003) 2667;
(c) W. Uhl, A. El-Hamdan, M. Prott, P. Spuhler, G. Frenking,
Dalton Trans. (2003) 1360.
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