The reactivity of gallium(I) and indium(I) halides towards bipyridines, terpyridines, imino-substituted pyridines and bis(imino)acenaphthenes

Article abstract of DOI:10.1039/b310592j

GaI reacts with 2,2′-bipyridine (bipy) to give salts of composition [Ga(bipy)₃][I]₃, [{(bipy)₂Ga} ₂-(μ-OH)₂]₂[Ga₂I ₆][I]₆ or [{(bipy)₂Ga}₂(μ-OH) ₂][I]₄, depending upon the reaction conditions. GaI also reacts with 4′-phenyl-2,2′:6′,2″- terpyridine (Phterpy) to give the salt [GaI₂(Phterpy)][I]. When GaI is treated with the imino-substituted pyridines RN=C(H)Py, Py = 2-pyridyl, R = Ar (C₆H₃Prⁱ₂-2,6) or Bu^t, a reductive coupling of the C=N functionality occurs to give the diamido-digallium(III) complexes [{I₂Ga[η²-(Py) (NR)C(H)]}₂]. In contrast, InCl reacts with ArN=C(H)Py to give an adduct, [InCl₃(THF) {η²-ArN=C(H)Py}], via disproportionation of the metal halide. Similarly, the reaction of the bis(imino)pyridine, 2,6-{ArN=C(Me)}₂(NC₅H₃), bimpy, with GaI affords the salt [GaI₂(bimpy)][GaI ₄]. Finally, the reaction of bis(2,6-diisopropylphenylimino) acenaphthene (ArBIAN) with GaI leads to a paramagnetic Ga(III) complex [GaI₂(ArBIAN)^?]. The X-ray crystal structures of all prepared complexes are reported.

Full text of DOI:10.1039/b310592j

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P A P E R
The reactivity of gallium(I) and indium(I) halides towards bipyridines,
terpyridines, imino-substituted pyridines and bis(imino)acenaphthenes
Robert J. Baker, Cameron Jones,* Marc Kloth and David P. Mills
Department of Chemistry, Cardiff University, P.O. Box 912, Park Place, Cardiff,
UK CF10 3TB. E-mail: jonesca6@cardiff.ac.uk
Received (in London, UK) 1st September 2003, Accepted 26th October 2003
First published as an Advance Article on the web 4th December 2003
‘‘GaI’’ reacts with 2,20-bipyridine (bipy) to give salts of composition [Ga(bipy)3][I]3 , [{(bipy)2Ga}2-
(m-OH)2]2[Ga2I6][I]6 or [{(bipy)2Ga}2(m-OH)2][I]4 , depending upon the reaction conditions. ‘‘GaI’’
also reacts with 40-phenyl-2,20:60,200-terpyridine (Phterpy) to give the salt [GaI2(Phterpy)][I]. When ‘‘GaI’’ is
i
t
=
treated with the imino-substituted pyridines RN C(H)Py, Py ¼ 2-pyridyl, R ¼ Ar (C6H3Pr 2-2,6) or Bu ,
=
a reductive coupling of the C N functionality occurs to give the diamido-digallium(III) complexes
[{I2Ga[Z -(Py)(NR)C(H)]}2]. In contrast, InCl reacts with ArN C(H)Py to give an adduct, [InCl3(THF)
{Z -ArN C(H)Py}], via disproportionation of the metal halide. Similarly, the reaction of the bis(imino)pyridine,
=
2,6-{ArN C(Me)}2(NC5H3), bimpy, with ‘‘GaI’’ affords the salt [GaI2(bimpy)][GaI4]. Finally, the reaction of
2
=
2
=
bis(2,6-diisopropylphenylimino)acenaphthene (ArBIAN) with ‘‘GaI’’ leads to a paramagnetic Ga(III) complex
[GaI2(ArBIAN)ꢀ]. The X-ray crystal structures of all prepared complexes are reported.
Introduction
of the salt [Ga(bipy)3][I]3 , 1, after recrystallisation from aceto-
nitrile (Scheme 1). This reaction proceeds via a disproportio-
nation process as evidenced by the deposition of considerable
gallium metal from the reaction mixture. The spectroscopic
data for 1 are consistent with its formulation and an X-ray
crystal structural analysis of the compound was carried out
to confirm this. The structure of the cationic component of
1 is depicted in Fig. 1 (see Table 1) and, surprisingly, repre-
sents the first structurally authenticated example of a homo-
leptic bipyridine complex of any group 13 element. The
geometry around the gallium centre is distorted octahedral,
In the past five years there has been much interest in the
chemistry of metastable aluminium(I) and gallium(I) halide
complexes [{MX(L)}n] (M ¼ Al, Ga; X ¼ halide; L ¼ ether,
amine or phosphine), which can only be synthesised in spe-
cially designed reactors.1 The further chemistry of these species
has been widely explored and shown to give rise to
an array of remarkable sub-oxidation state complexes.2 An
alternative to these reactor generated halide complexes is avail-
able with ‘‘GaI’’ which has been reported by Green et al.3
to be simply formed by sonicating gallium metal with 0.5
equivalents of I2 . Although its formulation has not been
definitely established, its reactivity has indicated that it can
be used as a source of Ga(I). We have begun to explore the
synthetic potential of ‘‘GaI’’, for example in its reactions with
diazabutadienes (DAB) which lead to paramagnetic Ga(II) and
Ga(III) complexes of the type [{(DABꢀ)GaI}2] and
[GaI2(DABꢀ)]. Both of these complexes are readily reduced
to novel anionic Ga(I) N-heterocyclic carbene analogues,
e.g. [K(TMEDA)][:Ga{N(Ar)CH}2], Ar ¼ C6H3Pri2-2,6,4 the
further chemistry of which is proving fruitful.5 In addition,
we have also observed that ‘‘GaI’’ reacts with primary and
secondary amines, secondary phosphines or N-heterocyclic
carbenes to give a variety of Ga(II) iodide complexes via
disproportionation reactions.6 It is noteworthy that others
have seen similar reactivity with tertiary amines,7 phosphines8
and arsines.9 In the present study we have expanded on this
work by examining the reactivity of several unsaturated
bi- and tridentate N-donor ligands towards ‘‘GaI’’ and InCl
in the hope of preparing new complexes that could be used
as precursors to group 13 N-heterocyclic carbene analogues.
In all cases, disproportionation and formation of M(III) com-
plexes occurred, though considerable variations in reactivity
and complex type formed were observed for the ligand classes
investigated. The results of this study are presented herein.
˚
with an average Ga–N bond length of 2.063 A. This value
is in the normal range for bipy complexes of gallium(III).10
The three iodide anions do not display any short contacts
with the cation or themselves. It is noteworthy that the com-
plex crystallises in the chiral space group, Pna21 , and in the
crystal selected for the X-ray experiment the cation exists as
its L-isomer.
In the first attempted preparation of 1, two salts containing
hydroxy-bridged digallium(III) tetracations, viz. [{(bipy)2Ga}2-
(m-OH)2]2[Ga2I6][I]6 2 and [{(bipy)2Ga}2(m-OH)2][I]4 3, were
formed in low yields as yellow crystalline solids which were
manually separated from orange 1. Both compounds presum-
ably form as a result of hydrolysis arising from contamination
of the solvent or bipy starting material with water (Scheme 1).
It is noteworthy that 2 is a rare example of a complex contain-
ing gallium atoms in mixed oxidation states, i.e. Ga(III) in the
cation and Ga(II) in the [Ga2I6]2ꢁ dianion. The spectroscopic
features of both complexes are very similar and support their
formulations. Most significantly, broad absorptions at 3420
cmꢁ1 in their IR spectra, and singlet peaks at d 2.05 ppm in
their 1H NMR spectra can be assigned to the bridging hydroxy
groups. The proton NMR resonances can be compared to
those observed for other hydroxy-bridged gallium dimers, e.g.
d 1.79 ppm for [{[(Me3Si)2CH]2Ga(m-OH)}2].11
Crystals of 2 and 3 suitable for X-ray diffraction were
obtained from acetonitrile solutions. The structures of the
cations in each are identical within experimental error and thus
only that for 2 will be discussed here (Fig. 2, see Table 1). The
geometry around the gallium atoms is distorted octahedral and
Results and discussion
The reaction of ‘‘GaI’’ with one equivalent of 2,20-bipyridine
(bipy) in toluene unexpectedly led to the high yield formation
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3
207

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t
=
Scheme 1 Reagents and conditions: i, bipy, toluene, ꢁGa; ii, bipy/H2O, toluene, ꢁGa; iii, Phterpy, toluene, ꢁGa; iv, Bu N C(H)Py, toluene,
ꢁGa; v, bimpy, toluene, ꢁGa; vi, ArBIAN, toluene, ꢁGa.
and 99.6(1)ꢂ respectively for [{(Mes)2Ga}2(m-OH)2].13 The
metric parameters of the [Ga2I6]2ꢁ counter ion are almost iden-
tical to those seen for [PPh3H][Ga2I6].14 It is interesting to note
that one Raman spectroscopic study has suggested that the
‘‘GaI’’ starting material used in the formation of 2 exists as
[Ga]2þ[Ga2I6]2ꢁ and thus contains this dianion.15
˚
the average Ga–N bond length, 2.078 A, is similar to that
12
˚
observed for 1 and cis-[(bipy)2GaCl2][GaCl4] [2.103 A av.].
There are no significant differences in the lengths of the Ga–
N bonds that are trans to a nitrogen or oxygen atom. More-
˚
over, the Ga–O bond lengths at 1.940 A (av.) and Ga–O–Ga
angles at 102.9ꢂ (av.) are similar to other hydroxy-bridged gal-
˚
lium(III) compounds reported in the literature, e.g. 1.949(2) A
For sake of comparison the 1:1 reaction of the tridentate
40-phenyl-2,20:60,200-terpyridine (Phterpy) ligand with ‘‘GaI’’ in
toluene was carried out and this gave rise to a yellow, insoluble
precipitate. On recrystallisation of this precipitate from aceto-
nitrile the salt [GaI2(Phterpy)][I], 4, could be isolated in a
high yield (Scheme 1). Due to its poor solubility in common
organic solvents, little meaningful spectroscopic data could be
obtained on the complex and so crystals suitable for X-ray dif-
fraction were grown from acetonitrile in order to determine its
structure, the cationic component of which is depicted in Fig. 3
(see Table 1). The geometry around the gallium atom is dis-
torted trigonal bipyramidal, with N(1) and N(3) taking up
the axial positions [N(1)–Ga(1)–N(3) 154.6(2)ꢂ]. As would be
˚
expected, the two axial Ga–N bonds are longer [2.104 A av.]
˚
than the equatorial bond, [Ga(1)–N(2) 2.007(5) A], though
˚
the average length for all three [2.071 A] is close to that
16
˚
observed for neutral [GaCl3(terpy)] [2.086 A av.] and com-
plexes 1–3. The Ga–I bond distances are in the normal range10
and the iodide anion has no close contacts with the cation.
It was thought of sufficient interest to examine the reactivity
=
of the imino-substituted pyridines, RN C(H)Py, Py ¼
2-pyridyl, R ¼ Ar (C6H3Pri2-2,6) or But, with ‘‘GaI’’ as such
compounds often display similar coordination chemistry to
both bipyridines and 1,4-diazabutadienes. In this case, how-
ever, significant differences were observed and the 1:2 reactions
led to intermolecular reductive couplings of two imine carbon
centres with concomitant gallium iodide disproportionation to
give good yields of the diamido-digallium(III) complexes, 5 and
6 (Scheme 1). The spectroscopic data for both confirm that a
Fig. 1 Structure of the cationic component of 1. Selected bond
lengths (A) and angles (ꢂ): Ga(1)–N(1) 2.070(6), Ga(1)–N(2)
˚
2.056(5), Ga(1)–N(3) 2.062(6), Ga(1)–N(4) 2.053(6), Ga(1)–N(5)
2.071(5), Ga(1)–N(6) 2.069(6); N(1)–Ga(1)–N(2) 80.1(2), N(1)–
Ga(1)–N(3) 93.92(19), N(1)–Ga(1)–N(4) 171.4(2), N(1)–Ga(1)–N(5)
93.7(2), N(1)–Ga(1)–N(6) 91.5(2), N(2)–Ga(1)–N(3) 91.3(2), N(2)–
Ga(1)–N(4) 94.2(2), N(2)–Ga(1)–N(5) 172.3(3), N(2)–Ga(1)–N(6)
95.6(2), N(3)–Ga(1)–N(4) 79.8(2), N(3)–Ga(1)–N(5) 93.8(2), N(3)–
Ga(1)–N(6) 171.9(2), N(4)–Ga(1)–N(5) 92.4(2), N(4)–Ga(1)–N(6)
95.4(2), N(5)–Ga(1)–N(6) 79.9(2).
=
ligand coupling has occurred. Specifically, no C N stretching
absorptions were observed in their IR spectra, and methine
resonances at d 4.20 ppm (5) and 5.29 ppm (6) could be seen
in the 1H NMR spectra of the complexes. Additionally, in
13
the C NMR spectrum of 5 the C N resonance of the
=
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
208
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3

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Table 1 Crystal data for compounds 1–9
1ꢃ4CH3CN
2ꢃ8CH3CN 3ꢃ5CH3CN 4ꢃCH3CN
5
6
7
8
9ꢃ0.5C6H14
Chemical
formula
Mr
C38H36
GaI3N10
1083.19
C96H92Ga6 C50H49Ga2 C23H18GaI3N4 C36H44Ga2 C20H28Ga2 C22H30Cl3
C33H43Ga2 C39H40
I12N24O4
3587.06
I4N13O2
1511.06
I4N4
I4N4
InN2O
559.65
Monoclinic Monoclinic Orthorhombic Triclinic
I6N3
1382.54
GaN2I2
860.25
Triclinic
800.83
Triclinic
1179.79
971.50
Crystal system
Space group
Orthorhombic Monoclinic Triclinic
¯
P1
¯
P1
¯
P1
¯
P1
Pna21
21.246(4)
17.803(4)
11.048(2)
90
C2/c
C2/c
P21/n
9.6170(19)
14.831(3)
10.140(2)
90
Pbca
˚
a/A
28.873(6)
14.539(3)
29.261(6)
90
11.000(2)
12.525(3)
21.899(4)
105.18(3)
94.44(3)
99.69(3)
2846.8(10)
2
7.3570(15)
13.306(3)
13.759(3)
99.44(3)
97.59(3)
102.53(3)
1277.2(5)
2
22.813(5)
14.364(3)
17.672(4)
90
17.008(3)
16.621(3)
17.465(4)
90
10.285(2)
13.001(3)
16.458(3)
76.95(3)
86.76(3)
81.91(3)
2121.8(7)
2
12.480(3)
12.706(3)
13.148(3)
70.68(3)
77.02(3)
81.03(3)
1909.6(7)
2
˚
b/A
˚
c/A
a/ꢂ
b/ꢂ
gꢂ
90
90
101.29(3)
90
124.81(3)
90
107.11(3)
90
90
90
3
˚
V/A
4178.8(14)
4
150(2)
12 046(4)
4
4754.6(17)
4
1382.3(5)
2
4937.2(17)
8
Z
T/K
150(2)
4.454
62 937
150(2)
3.165
49 843
150(2)
4.720
22 859
150(2)
3.756
21 124
150(2)
6.431
8771
150(2)
1.297
23 141
150(2)
5.660
26 217
150(2)
2.364
25 014
m(Mo-Ka)/mmꢁ1 2.914
Reflections
collected
34 157
8934
Unique reflns.
(Rint)
11 727
(0.0924)
0.0569
0.1319
12 403
(0.1738)
0.0553
0.1446
4945
5406
2811
4490
7606
6880
(0.0865)
(0.0980)
0.0450
0.0970
(0.0587)
0.0325
0.0736
(0.0589)
0.0290
0.0683
(0.1004)
0.0463
0.0995
(0.1385)
0.0655
0.1757
(0.0523)
0.0512
0.1252
R1 (I > 2s(I))
wR2 (all data)
0.0484
0.1174
iminopyridine starting material has been replaced by one at d
71.53 ppm that was assigned to the NC(H)C(H)N moiety
of the coupled ligand. Unfortunately, the low solubility of
compound 6 in normal deuterated solvents prevented the
acquisition of meaningful 13C NMR data.
Crystals of both compounds were grown from DME solu-
tions and their X-ray crystal structures obtained (Figs. 4 and
5, see Table 1). Both structures confirm that coupling reactions
have occurred and both compounds exist in their meso-
isomeric form. Each gallium centre is chelated by a covalent
amido interaction and a dative interaction from the pyridyl
substituents. In addition, each gallium centre has a heavily
distorted tetrahedral geometry which arises from the small
bite angle of the ligands [N(1)–Ga(1)–N(2) 5: 85.90(10)ꢂ;
6: 88.05(13)ꢂ], whilst the dative and covalent Ga–N bond
lengths differ significantly in each complex [pyridyl N(1)–
˚
Ga(1) 5: 1.974(3) A, 6: 2.020(3) A; amido N(2)–Ga(1) 5:
˚
˚
˚
1.869(2) A, 6: 1.884(3) A]. Finally, it is worth noting that the
distances between the coupled carbon centres are longer than
would normally be expected for C(sp3)–C(sp3) bonds [C(6)–
0
˚
˚
C(6 ) 5: 1.603(5) A, 6: 1.581(7) A] though there is precedent
for this in NCCN moieties of reductively coupled diazabuta-
diene complexes in which each N-centre is covalently bonded
to a metal.17
Transition metal mediated C–C couplings of diazabutadiene
ligands have been observed on many occasions.18 Similarly,
the reductive coupling of iminopyridines have been reported.
Most relevant to this study is that which arises from the
t
19
=
reaction of Bu N C(H)Py with ZnEt2 . This leads to a
diamagnetic, dimeric complex which closely resembles 6, viz.
[{EtZn[Z2-(Py)(NBut)C(H)]}2]. The mechanism of formation
Fig. 2 Structure of the cationic component of 2. Selected bond
ꢂ
˚
lengths (A) and angles ( ): Ga(1)–O(1) 1.942(5), Ga(1)–O(2) 1.941(5),
Ga(2)–O(1) 1.942(5), Ga(2)–O(2) 1.937(5), Ga(1)–N(1) 2.071(6),
Ga(1)–N(2) 2.094(6), Ga(1)–N(3) 2.066(6), Ga(1)–N(4) 2.085(7), Ga(2)–
N(5) 2.070(6), Ga(2)–N(6) 2.075(6), Ga(2)–N(7) 2.078(6), Ga(2)–N(8)
2.088(6); O(1)–Ga(1)–O(2) 77.0(2), O(1)–Ga(1)–N(1) 166.4(2), O(1)–
Ga(1)–N(2) 91.5(2), O(1)–Ga(1)–N(3) 93.4(2), O(1)–Ga(1)–N(4) 99.5(2),
O(1)–Ga(2)–N(5) 91.7(2), O(1)–Ga(2)–N(6) 92.7(2), O(1)–Ga(2)–N(7)
169.2(2), O(1)–Ga(2)–N(8) 93.8(2), O(2)–Ga(1)–N(1) 95.8(2), O(2)–
Ga(1)–N(2) 98.4(2), O(2)–Ga(1)–N(3) 164.1(2), O(2)–Ga(1)–N(4)
90.3(2), O(2)–Ga(2)–N(5) 165.1(2), O(2)–Ga(2)–N(6) 92.7(2), O(2)–
Ga(2)–N(7) 95.7(2), O(2)–Ga(2)–N(8) 95.8(2), Ga(1)–O(1)–Ga(2)
102.8(2), Ga(1)–O(2)–Ga(2) 103.0(2).
Fig. 3 Structure of the cationic component of 4. Selected bond
lengths (A) and angles (ꢂ): Ga(1)–I(1) 2.5389(11), Ga(1)–I(2)
˚
2.5144(12), Ga(1)–N(1) 2.087(5), Ga(1)–N(2) 2.007(5), Ga(1)–N(3)
2.121(5); N(1)–Ga(1)–N(2) 77.4(2), N(1)–Ga(1)–N(3) 154.6(2), N(1)–
Ga(1)–I(1) 97.08(15), N(1)–Ga(1)–I(2) 96.75(15), N(2)–Ga(1)–N(3)
77.3(2), N(2)–Ga(1)–I(1) 122.34(15), N(2)–Ga(1)–I(2) 120.29(15),
N(3)–Ga(1)–I(1) 95.11(15), N(3)–Ga(1)–I(2) 97.32(15), I(1)–Ga(1)–
I(2) 117.37(4).
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3
209

View Article Online
complex suggested that the diamido ligand would have diffi-
culty in coordinating two metal centres in its meso-form which
is clearly not the case given the isolation of 6.
The reductive coupling of the iminopyridines by ‘‘GaI’’
highlights the potential usefulness of this as a reagent in
organic synthesis. This potential has only been demonstrated
once before in the reaction of ‘‘GaI’’ with a 1,3-diyne, which
led to a reductive C–C coupling of the diyne to give a novel
ene-diyne-bis(gem-organodigallium(III)) complex.19 In that
report the greater reducing ability of ‘‘GaI’’ over indium(I)
halides was highlighted by the fact that InI did not react with
the diyne. Despite this, previous reports have shown that
indium metal can be used to couple imines to form 1,2-di-
amines.20 Therefore we wished to see if indium(I) halides would
be sufficiently reducing to couple the imino-substituted pyri-
dines used in this study. To this end, InCl was treated with
=
0.5 equivalents of ArN C(H)Py which led to deposition of
indium metal and the moderate yield formation of the adduct
=
2
complex, [InCl3{Z -ArN C(H)Py}(THF)] 7, by a dispropor-
tionation reaction. This result confirms the weaker reducing
ability of InCl over ‘‘GaI’’. Complex 7 was subsequently
=
prepared by the direct treatment of ArN C(H)Py with InCl3
in THF. The spectroscopic data for the complex support its
˚
Fig. 4 Molecular structure of 5. Selected bond lengths (A) and angles
(ꢂ): Ga(1)–I(1) 2.5092(13), Ga(1)–I(2) 2.5485(5), Ga(1)–N(1) 1.974(3),
Ga(1)–N(2) 1.869(2), N(2)–C(6) 1.462(3), C(6)–C(60) 1.603(5), C(5)–
C(6) 1.526(4); I(1)–Ga(1)–I(2) 106.94(2), I(1)–Ga(1)–N(1) 115.85(7),
I(I)–Ga(1)–N(2) 118.99(8), I(2)–Ga(1)–N(1) 102.66(8), I(2)–Ga(1)–
N(2) 123.56(8), N(1)–Ga(1)–N(2) 85.90(10), Ga(1)–N(2)–C(6)
115.52(18), C(6)–N(2)–C(7) 119.4(2), Ga(1)–N(2)–C(7) 121.75(18).
Symmetry operation: ꢁx þ 1, y, ꢁz þ 3/2.
=
proposed structure, especially the observed C N stretching
absorption at 1652 cmꢁ1 in its IR spectrum. In addition, a
resonance at d 127.5 ppm in the 13C NMR spectrum of the
compound was assigned to the imine carbon.
Crystals of 7 were grown from a THF solution and its X-ray
crystal structure obtained. (Fig. 6, see Table 1). The geometry
around the indium atom is distorted octahedral with a fac-
arrangement of the chloride ligands, whilst the bond lengths
within the five-membered chelate ring are consistent with a
of this complex has been shown to involve aꢀparamagnetic
monomeric intermediate, [EtZn{ButNC(H)Py} ], via loss of
an ethyl radical. It was confirmed that in solution this inter-
mediate is in equilibrium with its diamagnetic dimer. Given
this, and the fact that our previously reported reactions of dia-
zabutadienes (DAB) with ‘‘GaI’’ lead to paramagnetic com-
plexes of the type [{(DABꢀ)GaI}2],4 it seems entirely feasible
that the mechanism of formation of 5 and 6 involves a one-
electron reduction of the ligand by ‘‘GaI’’, followed by radical
coupling and disproportionation reactions to give the observed
products. One difference between 5 and 6, and [{EtZn[Z2-
(Py)(NBut)C(H)]}2] is the fact that the former exist as their
meso-isomers whereas the latter crystallises as its RR0/SS0-
enantiomeric pair. Interestingly, the report on the zinc
˚
=
localised C N interaction [C(6)–N(2) 1.273(6) A and C(5)–
˚
C(6) 1.458(6) A]. These bond lengths are similar to those
=
observed in the related complex [NiCl2{ArN C(H)Py}]2 , i.e.
21
˚
˚
1.278(3) A and 1.463(4) A respectively. Both the pyridyl
N–In and imine N–In bond lengths are unremarkable.
˚
Fig. 6 Molecular structure of 7. Selected bond lengths (A) and angles
(ꢂ): In(1)–N(1) 2.306(4), In(1)–N(2) 2.348(4), In(1)–Cl(1) 2.4381(13),
In(1)–Cl(2) 2.4103(13), In(1)–Cl(3) 2.4405(13), In(1)–O(1) 2.396(3),
C(6)–N(2) 1.273(6), C(5)–C(6) 1.458(6); N(1)–In(1)–N(2) 71.72(13),
N(1)–In(1)–Cl(1) 97.54(10), N(1)–In(1)–Cl(2) 156.94(10), N(1)–In(1)–
Cl(3) 91.53(10), N(1)–In(1)–O(1) 77.16(12), N(2)–In(1)–Cl(1)
92.14(10), N(2)–In(1)–Cl(2) 93.21(10), N(2)–In(1)–Cl(3) 162.10(9),
N(2)–In(1)–O(1) 85.69(12), Cl(1)–In(1)–Cl(2) 100.44(5), Cl(1)–In(1)–
Cl(3) 96.41(5), Cl(2)–In(1)–Cl(3) 100.63(5), Cl(1)–In(1)–O(1)
174.67(8), Cl(2)–In(1)–O(1) 84.55(9), Cl(3)–In(1)–O(1) 84.39(9).
˚
Fig. 5 Molecular structure of 6. Selected bond lengths (A) and angles
(ꢂ): Ga(1)–I(1) 2.5490(6), Ga(1)–I(2) 2.5232(6), Ga(1)–N(1) 2.020(3),
Ga(1)–N(2) 1.884(3), N(2)–C(6) 1.459(5), C(6)–C(60) 1.581(7), C(1)–
C(6) 1.522(5); I(1)–Ga(1)–I(2) 110.38(2), I(1)–Ga(1)–N(1) 106.81(9),
I(1)–Ga(1)–N(2) 114.58(9), I(2)–Ga(1)–N(1) 104.24(9), I(2)–Ga(1)–
N(2) 127.22(9), N(1)–Ga(1)–N(2) 88.05(13), Ga(1)–N(2)–C(6)
107.5(2), C(6)–N(2)–C(7) 116.7(3), Ga(1)–N(2)–C(7) 121.6(2). Symme-
try operation: ꢁx, ꢁy, ꢁz þ 1.
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
210
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3

View Article Online
expected and complex 9 was isolated in moderate yield after
The potentially tridentate 2,6-bis(imino)pyridine ligand, 2,6-
=
{ArN C(Me)}2(NC5H3), bimpy, has been recently used in
recrystallisation from hexane (Scheme 1). The complex is para-
magnetic and its EPR spectrum shows only a broad signal
centred at g ¼ 2.0032 (298 K) indicating that the unpaired
electron is mainly ligand based. As no meaningful NMR data
could be obtained for this compound an X-ray crystal struc-
tural analysis was carried out and its molecular structure is
depicted in Fig. 8 (see Table 1). The gallium centre possesses
a distorted tetrahedral geometry with an acute N–Ga–N angle
[86.67(16)ꢂ]. This is, however, slightly more obtuse than those
observed in the closely related complexes ꢀ[GaCl2(Ar-BIAN)]-
non-metallocene based olefin polymerisation catalysts with
great effect.22 Its reactivity towards main group compounds
has also been investigated and shown to give interesting
results. For example, its reaction with AlMe3 leads to carbo-
metallation of one imine arm of the ligand to give a complex
that is a precursor to an active ethylene polymerisation cata-
lyst.23 In light of this result and the similarity of the bimpy
ligand to others utilised in this study we have investigated its
reaction with ‘‘GaI’’ in toluene, which again leads to dispro-
portionation of the gallium starting material and the low yield
formation of the salt [GaI2(bimpy)][GaI4] 8 (Scheme 1). The
[GaCl4] [85.1(2)ꢂ]26 and [GaI2{[ArNC(H)] }] [85.71(6)ꢂ].27 In
2
˚
addition, the Ga–N [1.957 A av.], C–N [1.334 A av.] and back-
˚
˚
bone C–C [1.436(6) A] bond lengths are close to those seen in
=
IR spectrum of the compound displays a C N stretching
ꢀ
absorption at 1628 cmꢁ1, whilst its 13C NMR spectrum exhi-
[GaI2{[ArNC(H)] }] [1.9449(10), 1.3386(15) and 1.406(2) A,
2
˚
=
bits a C N resonance at d 169.0 ppm. Both data confirm
respectively]. As in that compound, these values indicate a
degree of delocalisation over the ligand. The reduction of 8
to a gallium(I) carbene analogue will be reported in a future
publication.
that the imino functionalities were not reduced and no C–C
coupling reactions had occurred, cf. the situation with 5 and 6.
The structure of the cationic moiety of 8 is depicted in Fig. 7.
Its gallium centre has a distorted square based pyramidal geo-
metry, with the basal plane defined by the N(1), N(2), N(3) and
I(2) centres, whilst the apical position is taken up by I(1). The
metric parameters also confirm the spectroscopic observation
Conclusion
=
of a simple adduct formation as the C N bond lengths
In conclusion, the reactivity of ‘‘GaI’’ towards bipyridines,
terpyridines, imino-substituted pyridines and imino-substi-
tuted acenaphthenes has been investigated with a variety of
different outcomes depending on the ligand system employed.
All reactions are, however, accompanied by disproportiona-
tion of the gallium starting material to give Ga(III) complexes.
Reaction of ‘‘GaI’’ with bipy affords the homoleptic tricat-
ionic complex, [Ga(bipy)3][I]3 , whilst reaction with Phterpy
yields a monocationic complex, [GaI2(Phterpy)][I]. Reaction
˚
˚
[1.284 A av.] are close to those in the free ligand [1.273 A
av.].24 Both imino N–Ga bond lengths [2.203 A av.] are signi-
˚
ficantly longer than the pyridyl N–Ga interaction [Ga(1)–N(2)
˚
2.014(7) A] which itself is comparable with those of the other
complexes in this study.
Because of its similarity to diazabutadienes, the final ligand
investigated in this study was bis(2,6-diisopropylphenyl)ace-
naphthene (ArBIAN). It has, however, been reported that it
is a better s-donor and p-acceptor ligand than less rigid 1,4-
diazabutadienes.25 It was, therefore, thought that if it reacted
similarly with ‘‘GaI’’ to form a paramagnetic complex,
[GaI2(ArBIAN)ꢀ], then this complex could be reduced to
a gallium carbene analogue that would perhaps have greater
stability than our aforementioned DAB based system.4 The
reaction of ArBIAN with ‘‘GaI’’ did, indeed, proceed as
Fig. 7 Structure of the cationic component of 8. Selected bond
lengths (A) and angles (ꢂ): Ga(1)–I(1) 2.5442(13), Ga(1)–I(2)
˚
˚
Fig. 8 Molecular structure of 9. Selected bond lengths (A) and angles
2.4919(14), Ga(1)–N(1) 2.182(7), Ga(1)–N(2) 2.014(7), Ga(1)–N(3)
2.225(8), C(1)–N(1) 1.291(12), C(1)–C(29) 1.518(13), C(2)–N(3)
1.278(12), C(2)–C(33) 1.331(12); I(1)–Ga(1)–I(2) 120.74(5), I(1)–
Ga(1)–N(1) 101.0(2), I(1)–Ga(1)–N(2) 93.7(2), I(1)–Ga(1)–N(3)
99.6(2), I(2)–Ga(1)–N(1) 97.4(2), I(2)–Ga(1)–N(2) 145.5(2), I(2)–
Ga(1)–N(3) 95.9(2), N(1)–Ga(1)–N(2) 75.9(3), N(1)–Ga(1)–N(3)
145.0(3), N(2)–Ga(1)–N(3) 74.8(3).
(ꢂ): Ga(1)–I(1) 2.5099(13), Ga(1)–I(2) 2.5015(12), Ga(1)–N(1) 1.961(4),
Ga(1)–N(2) 1.954(4), N(1)–C(1) 1.335(6), N(2)–C(2) 1.332(6), C(1)–
C(2) 1.436(6), C(1)–C(27) 1.464(7), C(2)–C(36) 1.464(7), N(2)–Ga(1)–
N(1) 86.67(16); N(2)–Ga(1)–I(2) 117.30(12), N(1)–Ga(1)–I(2)
111.89(12), N(2)–Ga(1)–I(1) 112.81(12), N(1)–Ga(1)–I(1) 117.58(12),
I(1)–Ga(1)–I(2) 109.34(4), C(1)–N(1)–Ga(1) 108.6(3), C(2)–N(2)–
Ga(1) 108.6(3).
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3
211

View Article Online
[GaI2(Phterpy)][I] 4. To a suspension of ‘‘GaI’’ (1.30 mmol)
with mono(imino)pyridines leads to reductive coupling of the
coordinated ligand to give neutral diamido-digallium com-
plexes, [{I2Ga[Z2-(Py)(NR)C(H)]}2] (R ¼ But or Ar), whereas
the use of the bis(imino)pyridine, bimpy, affords the salt
[GaI2(bimpy)][GaI4]. Finally, reaction of ‘‘GaI’’ with the
bis(imino)acenaphthene, ArBIAN, yields the paramagnetic
complex, [GaI2(ArBIAN)ꢀ]. This work demonstrates the versa-
tility of ‘‘GaI’’ as a reagent in inorganic and organic synthesis,
which are areas we continue to explore.
in toluene (15 cm3) was added a solution of Phterpy (0.40 g,
1.30 mmol) in toluene (15 cm3) at ꢁ78 ꢂC. The resulting sus-
pension was warmed to room temperature and stirred over-
night to yield a yellow precipitate. Volatiles were removed
in vacuo and the residue extracted with CH3CN (30 cm3) then
filtered. Cooling the filtrate to ꢁ30 ꢂC overnight yielded yellow
crystals of 4 (0.28 g, 87%); mp 170–172 ꢂC (decomp.);
1H NMR (400 MHz, CD3CN, 298 K): d 7.67 (m, 3H,
o-/p-PhH), 8.01 (m, 2H, C5H), 8.10 (m, 2 H, m-PhH), 8.46
(m, 2H, C4H), 8.72 (m, 2 H, C3H), 8.94 (s, 2 H, C30H,
C50H), 8.97 (m, 2H, C6H); IR n/cmꢁ1 (Nujol): 1618(s),
1259(s), 1095(s), 1022(s), 800(s); MS/ESI m/z (%): 310
[PhterpyHþ, 100].
Experimental
General remarks
All manipulations were carried out using standard Schlenk and
glove-box techniques under an atmosphere of high purity
argon. The solvents toluene, DME and THF were distilled
over potassium whilst Et2O and hexane were distilled over
Na/K alloy. CH2Cl2 and CH3CN were distilled over CaH2
then freeze/thaw degassed prior to use. 1H and 13C NMR
spectra were recorded on either a Bruker DXP400 spectro-
meter operating at 400.13 and 100 MHz respectively, or a
JEOL Eclipse 300 spectrometer operating at 300.52 and
75.57 MHz, respectively. Spectra were referenced to either
the 13C or residual 1H resonances of the solvent used. Mass
spectra were recorded using a VG Fisons Platform II instru-
ment under APCI conditions, or were obtained from the
EPSRC National Mass Spectrometric Service at Swansea
University (ESI). IR spectra were recorded using a Nicolet
510 FT-IR spectrometer as a Nujol mulls between NaCl plates.
Melting points were determined in sealed glass capillaries
[{I2Ga[g2-(Py)(NAr)C(H)]}2] 5. To a suspension of ‘‘GaI’’
(2.86 mmol) in toluene (10 cm3) at ꢁ78 ꢂC was added a solu-
3
tion of ArN C(H)Py (0.38 g, 1.43 mmol) in toluene (10 cm )
=
and the resulting suspension warmed to room temperature
and stirred overnight to yield a green solution. This was fil-
tered and volatiles removed in vacuo. The residue was
extracted into Et2O (15 cm3)–DME (7 cm3) and the resulting
solution filtered. The filtrate was concentrated to ca 10 cm3
and cooled to ꢁ30 ꢂC overnight to yield yellow–green crystals
of 5 (0.22 g, 25%), mp 73–75 ꢂC (decomp.); 1H NMR (400
3
MHz, C6D6 , 300 K): d 1.25 (d, 12H, JHH ¼ 6.7 Hz, CH3),
1.29 (d, 12H, 3JHH ¼ 6.7 Hz, CH3), 3.23 (sept, 2H, 3JHH ¼ 6.7
Hz, CHMe2), 4.20 (s, 2H, CHN), 7.16 (t, 4H, 3JHH ¼ 10.3 Hz,
3
p-ArH), 7.27 (d, 4H, JHH ¼ 10.3 Hz, m-ArH), 8.04 (m, 2H,
Py-C5H), 8.39 (m, 2H, Py-C4H) 8.57 (m, 2H, Py-C3H), 8.71
(m, 2H, Py-C6H); 13C NMR (75 MHz, C6D6 , 300 K): d 23.3
(CH3), 24.9 (CH3), 28.2 (CHMe2), 71.5 (NC), 120.6
(p-Ar), 123.3 (m-Ar), 129.1 (o-Ar), 137.2 (Py-C5), 139.8
(ipso-Ar), 141.2 (Py-C4), 143.5 (Py-C3) 149.7 (Py-C6), 163.7
(Py-C2); IR (Nujol) n/cmꢁ1: 2895(s), 2353(w), 1609(w),
1564(w), 1459(s), 1377(m), 1261(w), 1105(m), 1053(m),
927(w), 800(m), 758(m), 719(m), 664(m); MS(APCI) m/z(%):
267 [ArN(H)C(H)Pyþ, 100], 223 [ArN(H)C(H)Pyþ ¼ Pri, 80].
under argon and are uncorrected. ‘‘GaI’’ was synthesised by
21
the literature method,3 as were the ligands ArN C(H)Py,
=
Bu N C(H)Py, bimpy29 and ArBIAN.30 Bipy and Phterpy
were obtained commercially and recrystallised from MeCN
prior to use, whilst InCl and InCl3 were used as received.
t
28
=
[Ga(bipy)3][I]3 1. To a suspension of ‘‘GaI’’ (5.80 mmol) in
toluene (15 cm3) was added a solution of 2,20-bipyridine (0.90
g, 5.80 mmol) in toluene (15 cm3) at ꢁ78 ꢂC over 5 min. The
resulting suspension was warmed to room temperature and
stirred overnight to yield a yellow–orange precipitate. Volatiles
were removed in vacuo and the residue extracted with CH3CN
(30 cm3) and filtered. Cooling of the filtrate to ꢁ30 ꢂC over-
night yielded orange crystals of 1 (1.28 g, 72%) mp 259–
261 ꢂC; 1H NMR (400 MHz, CD3CN, 298 K): d 7.51 (m,
6H, C5H), 7.81 (m, 6H, C4H), 8.41 (m, 6H, C3H), 8.51 (m,
6H, C6H); 13C NMR (100.6 MHz, CD3CN, 298 K): d 125.8
(C3), 128.7 (C5), 142.6 (C4), 146.7 (C6), 147.5 (C2); IR n/
cmꢁ1 (Nujol): 1602(m), 1319(s), 1260(s), 1102(s), 801(s); MS/
APCI m/z (%): 157 [bipyHþ, 100].
[{I2Ga[g2-(Py)(NBut)C(H)]}2] 6. To a suspension of ‘‘GaI’’
(2.86 mmol) in toluene (10 cm3) at ꢁ78 ꢂC was added a solu-
t
=
tion of Bu N C(H)Py (0.23 g, 1.43 mmol) in toluene (10
cm3) and the resulting suspension warmed to room tempera-
ture and stirred overnight to yield a green solution. This was
filtered and the volatiles removed in vacuo. The residue was
extracted into DME (15 cm3) and the resulting solution con-
centrated to ca. 10 cm3. Cooling to ꢁ30 ꢂC overnight yielded
yellow crystals of 6 (0.20 g, 29%), mp 113–115 ꢂC (decomp.);
1H NMR (300 MHz, CD2Cl2 , 300 K): d 1.34 (s, 18H, CH3),
5.29 (s, 2H, NCH), 8.17 (m, 2H, Py-C5H), 8.35 (m, 2H,
Py-C3H), 8.61 (m, 2H, Py-C4H), 8.98 (m, 2H, Py-C6H);
IR (Nujol) n/cmꢁ1
: 2926(s), 2723(w), 1603(w), 1459(s),
1376(s), 1260(m), 1071(m), 1020(m), 944(w), 801(w), 722(w);
MS(APCI) m/z(%): 972 [Mþ, 10], 163 [ButN(H)C(H)Pyþ,
100].
[{(bipy)2Ga}2(l-OH)2]2[Ga2I6][I]6 2 and [{(bipy)2Ga}2(l-OH)2]-
[I]4 3. In an attempted preparation of 1 in which the reaction
solvent was contaminated with water, the hydrolysis products,
2 (mp 140–142 ꢂC decomp.) and 3 (mp 146–148 ꢂC decomp.)
were formed in low yield (ca. 20% as a mixture). Manual
separation of 2 and 3 was achieved based on crystal morphol-
ogy and the spectroscopic data for each were found to be
indistinguishable. 1H NMR (400 MHz, CD3CN, 298 K): d
2.05 (br, 2H, OH), 7.40 (m, 4H, C5H), 7.48 (m, 4H, C50H),
8.26 (m, 4H, C4H), 8.42 (m, 4H, C40H), 8.53 (m, 4H, C3H),
8.64 (m, 4H, C30H), 8.76 (m, 4H, C6H), 8.83 (m, 4H, C60H);
13C NMR (100.6 MHz, CD3CN, 298 K): d 124.3 (C3), 124.8
(C30), 128.9 (C5), 129.0 (C50), 144.1 (C4), 145.0 (C4ꢁ0)1,
145.8 (C6), 146.4 (C60), 147.2 (C2), 147.6 (C20); IR n/cm
(Nujol): 3420(br), 1600(s), 1312(s), 1156(s), 1026(s), 774(s);
MS/APCI m/z (%): 469 [(bipy)2Ga2OHþ, 100].
2
[InCl3(THF){g -ArN C(H)Py}] 7. Method 1. To a suspen-
=
sion of InCl (0.25 g, 1.66 mmol) in THF (10 cm3) at 25 ꢂC
=
was added ArN C(H)Py (0.22 g, 0.83 mmol) in THF (10
cm3). The resulting suspension was stirred for 5 h to yield a
pale green solution. This was filtered, concentrated to ca. 10
ml and placed at ꢁ30 ꢂC overnight to yield yellow crystals of
7 (0.15 g, 49%).
Method 2. To a suspension of InCl3 (0.30 g, 1.35 mmol) in
3
ꢂ
=
THF (10 cm ) at 25 C was added ArN C(H)Py (0.36 g,
1.35 mmol) in THF (10 cm3) over 5 min. The resulting suspen-
sion was stirred for 5 h to yield a pale green solution. This was
filtered, concentrated to ca. 10 cm3 and placed at ꢁ30 ꢂC over-
night to yield yellow crystals of 7 (0.50 g, 66%); mp 282–285 ꢂC
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
212
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3

View Article Online
Mass Spectrometry Service at Swansea University is also
thanked.
1
(decomp.); H NMR (400 MHz, CD3CN, 300 K): d 0.98 (d, 6
3
3
H, JHH ¼ 6.6 Hz, CH3), 1.16 (d, 6H, JHH ¼ 6.6 Hz, CH3),
3
1.73 (m, 4H, CH2), 3.13 (sept, 2H, JHH ¼ 6.6 Hz, CHMe2),
3
3.54 (m, 4H, OCH2), 7.18 (d, 2H, JHH ¼ 6.3 Hz, m-ArH),
3
7.26 (t, 1H, JHH ¼ 6.3 Hz, p-ArH), 8.00 (m, 1H, Py-C5H),
References
8.10 (m, 1H, Py-C3H), 8.34 (m, 1H, Py-C4H), 8.60 (s, 1H,
NCH), 9.09 (m, 1H, Py-C6H); 13C NMR (100.6 MHz,
CD3CN, 300 K): d 22.1 (CH2), 24.1 (CH3), 24.9 (CH3), 27.7
(CHMe2), 66.9 (OCH2), 118.0 (p-Ar), 123.5 (m-Ar), 127.5
(CN), 130.8 (o-Ar), 139.9 (Py-C4), 140.9 (ipso-Ar), 142.5 (Py-
C5), 145.8 (Py-C3), 148.4 (Py-C6), 163.5 (Py-C2); IR (Nujol)
n/cmꢁ1: 2897(s), 1652(w), 1586(w), 1462(s), 1376(s), 1261(m),
1152(m), 1091(m), 1019(m), 803(m), 722(m); MS(APCI) m/z
(%): 487 [Mþ ꢁ THF, 12], 267 [ArN(H)C(H)Pyþ, 100].
1
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4
5
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[GaI2(bimpy)][GaI4] 8. To a suspension of ‘‘GaI’’ (2.58
mmol) in toluene (10 cm3) at 25 ꢂC was added a solution of
bimpy (0.31 g, 0.65 mmol) in toluene (10 cm3) over 5 min.
The resulting suspension was stirred overnight to yield a
yellow solution from which volatiles removed in vacuo. The
residue was washed with hexane (5 cm3) and extracted into
CH2Cl2 (3 cm3). Layering with hexane afforded yellow crystals
of 8 (0.06 g, 10%); mp 212–215 ꢂC; 1H NMR (300 MHz,
6
7
8
9
B. Beagley, S. Godfrey, K. Kelly, S. Kungwankunakorn, C.
McAuliffe and R. Pritchard, Chem. Commun., 1996, 2179.
3
CD2Cl2): d 1.10 (d, JHH ¼ 6.1 Hz, 12H, CH3), 1.24 (d,
3JHH ¼ 6.1 Hz, 12H, CH3), 2.7 (sept, JHH ¼ 6.1 Hz, 4H,
3
10 As determined from a survey of the Cambridge Crystallographic
Database (September 2003).
11 W. Uhl, I. Hahn, M. Kock and M. Layh, Inorg. Chim. Acta.,
1996, 249, 33.
12 R. Restivo and G. J. Palenik, J. Chem. Soc., Dalton. Trans.,
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Noltemeyer, R. Fleischer and D. Stalke, J. Am. Chem. Soc.,
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14 M. A. Khan, D. G. Tuck, M. J. Taylor and D. A. Rogers,
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Organometallics, 2001, 20, 860.
3
=
CHMe2), 2.79 (s, 6H, CH3C N), 7.32 (d, JHH ¼ 7.1 Hz,
3
4H, m-ArH), 7.41 (t, JHH ¼ 7.1 Hz, 2H, p-ArH), 8.86 (d,
3JHH ¼ 7.7 Hz, 2H, Py-C3H), 9.24 (t, JHH ¼ 7.7 Hz, 1H,
3
Py-C4H); 13C NMR (75 MHz, CD2Cl2): d 20.8 (CH3), 24.7
=
(CH3), 24.8 (CH), 29.8 (CH3C N), 124.9 (m-Ar), 129.3
(Py-C3), 131.0 (Py-C4), 136.4 (p-Ar), 140.8 (o-Ar), 142.7
=
ꢁ1
(ipso-Ar), 149.9 (Py-C2), 169.0 (C N); IR (Nujol) n/cm
:
2923(s), 1688(w), 1624(m), 1586(m), 1457(s), 1376(s),
1318(w), 1262(m), 1214(w), 1090(s), 1033(s), 935(w), 798(s),
775(m), 736(s); MS (APCI) m/z (%): 480 [bimpyHþ, 100].
16 G. Beran, A. J. Carty, H. A. Patel and G. J. Palenik, J. Chem. Soc.
D, 1970, 222.
17 E. Wissing, S. van der Linden, E. Rijnberg, J. Boersma, W. J. J.
Smeets, A. L. Spek and G. van Koten, Organometallics, 1994,
13, 2602, and references therein.
18 e.g.(a) L. H. Staal, A. Oskam, K. Vrieze, E. Roosendaal and H.
Schenk, Inorg. Chem., 1979, 18, 1634; (b) L. H. Staal, L. H. Polm,
R. W. Balk, G. van Koten, K. Vrieze and A. M. F. Brouwers,
Inorg. Chem., 1980, 19, 3343; (c) J. Keijsper, G. van Koten,
K. Vrieze, M. Zoutberg and C. H. Stam, Organometallics, 1985,
4, 1306.
19 R. J. Baker and C. Jones, Chem. Commun., 2003, 390.
20 N. Kalyanam and G. V. Rao, Tetrahedron Lett., 1993, 34, 1647.
21 T. V. Laine, M. Klinga and M. Leskela, Eur. J. Inorg. Chem.,
1999, 959.
[GaI2(ArBIAN)ꢀ] 9. To a suspension of ‘‘GaI’’ (4.00 mmol)
in toluene (10 cm3) at 25 ꢂC was added a slurry of ArBIAN
(1.00 g, 2.00 mmol) in toluene (40 ml) over 15 min and the
resulting suspension stirred overnight to yield a red solution.
Volatiles were removed in vacuo from this solution and the
residue extracted into hexane (80 cm3). Concentration to ca.
40 cm3 and placement at ꢁ30 ꢂC overnight gave large red
blocks of 9 (0.60 g, 36%); mp 225–227 ꢂC; IR (Nujol)
n/cmꢁ1
: 1385(m), 1319(w), 1256(m), 1188(m), 820(m),
801(m), 770(s), 760(w); MS accurate mass (EI) calc. for
C36H40N2I269Ga: m/z 823.0531, measured: 823.0512.
22 (a) G. J. P. Britovsek, V. C. Gibson, B. S. Kimberley, P. J.
Maddox, S. J. McTavish, G. A. Solan, A. J. P. White and D. J.
Williams, Chem. Commun., 1998, 848; (b) B. L. Small, M.
Brookhart and M. A. Bennett, J. Am. Chem. Soc., 1998, 120,
4049.
23 M. Bruce, V. C. Gibson, C. Redshaw, G. A. Solan, A. J. P. White
and D. J. Williams, Chem. Commun., 1998, 2523.
24 G. P. A. Yap and S. Gammbarotto, private communication to the
Cambridge Crystallographic Database.
25 R. van Asselt, C. J. Elsevier, W. J. J. Smeets, A. L. Spek and
R. Benedix, Recl. Trav. Chim. Pays-Bas, 1994, 113, 88.
26 H. A. Jenkins, C. L. Dumaresque, D. Vidovic and J. A. C.
Clyburne, Can. J. Chem., 2002, 80, 1398.
X-Ray crystallography
Crystals of 1–9 suitable for X-ray structural determination
were mounted in silicone oil and crystallographic measure-
ments made using a Nonius Kappa CCD diffractometer. The
structures were solved by direct methods and refined on F2
by full matrix least squares (SHELX97)31 using all unique
data. All non-hydrogen atoms are anisotropic with H-atoms
included in calculated positions (riding model). Crystal data,
details of data collections and refinement are given in Table 1.
CCDC reference numbers 223004–223012.
27 T. Pott, P. Jutzi, W. Kaim, W. W. Schoeller, B. Neumann, A.
Stammler, H. G. Stammler and M. Wanner, Organometallics,
2002, 21, 3169.
See http://www.rsc.org/suppdata/nj/b3/b310592j/ for
crystallographic data in CIF or other electronic format.
28 L. Chan and A. J. Lees, J. Chem. Soc., Dalton Trans., 1987, 513.
29 G. P. Britovsek, M. Bruce, V. C. Gibson, B. S. Kimberley, P. J.
Maddox, S. Mastroianni, S. J. McTavish, C. Redshaw, G. A.
Solan, S. Stroemberg, A. J. P. White and D. J. Williams, J. Am.
Chem. Soc., 1999, 121, 8728.
30 A. Pavlovicova, U. El-Ayaan, K. Shibayama, T. Morita and
Y. Fukuda, Eur. J. Inorg. Chem., 2001, 2641.
31 G. M. Sheldrick, SHELX-97, University of Go¨ttingen, 1997.
Acknowledgements
We thank the EPSRC (studentship for M. K. and postdoctoral
fellowship for R. J. B.) and the Nuffield foundation (DPM,
grant no. NUF-URB03) for financial support. The EPSRC
T h i s j o u r n a l i s Q 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 a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 0 7 – 2 1 3
213