The reactivity of primary and secondary amines, secondary phosphanes and N-heterocyclic carbenes towards group-13 metal(I) halides

Article abstract of DOI:10.1002/ejic.200300068

The reactions of a variety of primary and secondary amines and secondary phosphanes with GaI have been examined. In all cases disproportionation reactions occurred which led to the gallium(II) iodide complexes [Ga₂I₄(L)₂] [L = NCyH₂, NtBuH₂, NCy₂H, PCy₂H or PtBu₂H (Cy = cyclohexyl)]. All complexes have been crystallographically characterised and have been shown to be dimers possessing Ga-Ga bonds. The reaction of the sterically hindered N-heterocyclic carbene IPr [:CN(Ar)C₂H₂N(Ar) (Ar = C₆H₃iPr₂-2,6)] with GaI was also carried out and the novel salt [Ga₂I₅(IPr)][IPrH] was formed in good yield and crystallographically characterised. Finally, the related reaction of the less hindered cyclic carbene IMe [:CN(Me)C₂Me₂N(Me)] with InCl gave a low yield of the crystallographically characterised salt [{InCl(IMe)}₂(μ-Cl)(μ-O)][Cl] which presumably forms due to the presence of adventitious oxygen in the reaction mixture. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200300068

FULL PAPER
The Reactivity of Primary and Secondary Amines, Secondary Phosphanes and
N-Heterocyclic Carbenes towards Group-13 Metal( ) Halides
I
Robert J. Baker,[a] Helga Bettentrup,[a] and Cameron Jones*[a]
Keywords: Group-13 elements / Carbene ligands / Phosphanes / Sub-oxidation state
The reactions of a variety of primary and secondary amines
and secondary phosphanes with ‘‘GaI’’ have been examined.
In all cases disproportionation reactions occurred which led
to the gallium(II) iodide complexes [Ga2I4(L)2] [L = NCyH2,
NtBuH2, NCy2H, PCy2H or PtBu2H (Cy = cyclohexyl)]. All
carried out and the novel salt [Ga2I5(IPr)][IPrH] was formed
in good yield and crystallographically characterised. Finally,
the related reaction of the less hindered cyclic carbene IMe
[:CN(Me)C2Me2N(Me)] with InCl gave a low yield of the
crystallographically characterised salt [{InCl(IMe)}2(µ-Cl)(µ-
complexes have been crystallographically characterised and O)][Cl] which presumably forms due to the presence of ad-
have been shown to be dimers possessing Ga−Ga bonds. The
reaction of the sterically hindered N-heterocyclic carbene IPr
[:CN(Ar)C2H2N(Ar) (Ar = C6H3iPr2-2,6)] with ‘‘GaI’’ was also
ventitious oxygen in the reaction mixture.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
‘‘GaI’’ this led to partial disproportionation and the forma-
tion of the indium() bromide complex [In2Br4(IMes)2] with
IMes being the cyclic carbene :CN(Mes)C(H)C(H)N(Mes)
(Mes ϭ mesityl).[6] In the present study we have extended
this work by examining the reactivity of several NHCs
towards indium() and gallium() halides. In addition, the
reactions of a variety of primary and secondary amines and
secondary phosphanes with ‘‘GaI’’ have been carried out
and these have led to the formation of the first crystallo-
graphically characterised complexes of the type [Ga2I4(L)2]
(L ϭ NR2H, NRH2, PR2H).
Over the past five years there has been a rapidly increas-
ing interest in the chemistry of metastable aluminium() and
gallium() halide complexes [{MX(L)}n] (1: M ϭ Al or Ga;
X ϭ halide; L ϭ ether, amine or phosphane). These have
been invariably prepared by the co-condensation of the met-
al() halide with the donor solvent using a specially de-
signed reactor, and several have been crystallographically
characterised, for example [Al4Br4(NEt3)4].[1] Studies of the
reactivity of group-13 metal() halide complexes have pro-
vided an array of remarkable results, not least of which
come from their use in the formation of polyhedral halide,
such as [Al22Br20(THF)12], amide, such as [Ga84{N-
(SiMe3)2}20]4Ϫ, alkyl, such as [Ga19{C(SiMe3)3}6]Ϫ, and si-
lyl, such as [Ga26{Si(SiMe3)3}8]2Ϫ, metalloid clusters.[2] At-
tempts have been made to prepare 1, with M ϭ Ga and
L ϭ PEt3 or PPh3, from the reaction of PEt3 or PPh3 with
‘‘GaI’’.[3] These reactions, however, led to partial dispro-
portionation and the facile formation of the gallium() iod-
ide complexes [Ga2I4(PR3)2] (R ϭ Et or Ph), and the mixed
oxidation state complex [Ga3I5(PEt3)3], all of which were
crystallographically characterised. It is noteworthy that
only two other neutral gallium() iodide adducts
[Ga2I4(L)2] (L ϭ NEt3 [4] or AsEt3 [5]), which were prepared
by alternative routes, have been structurally authenticated.
Surprisingly there are no known structurally character-
ised indium analogues of 1. Recently, we attempted the
preparation of such a compound using an N-heterocyclic
carbene (NHC) as the donor ligand in a reaction with InBr.
As in the aforementioned reactions of phosphanes with
Results and Discussion
Amine and Phosphane Reactions
In all reactions depicted in Scheme 1 ‘‘GaI’’ was prepared
by sonicating gallium metal with 0.5 equiv. of I2 in toluene
at 50 °C according to the method of Green et al.[7] A tolu-
ene suspension of this material was treated with a variety
of amines and phosphanes at Ϫ78 °C. Upon warming the
reaction mixtures to room temperature gallium metal depo-
sition was observed. The resulting suspensions were filtered
and cooled to Ϫ30 °C affording moderate to high yields
of the gallium() iodide adducts 2Ϫ6. The mechanism of
formation of these compounds presumably involves partial
disproportionation of the ‘‘GaI’’ reagent upon treatment
with the Lewis bases. All compounds are, however, quite
stable at room temperature in both solution and the solid
state and no further disproportionation to gallium() iod-
ide complexes was observed.
[a]
Department of Chemistry, Cardiff University,
P. O. Box 912, Park Place, Cardiff, CF10 3TB, U.K.
2446
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200300068
Eur. J. Inorg. Chem. 2003, 2446Ϫ2451

Reactivity of Amines, Phosphanes and N-Heterocyclic Carbenes towards Group-13 Metal(I) Halides
FULL PAPER
nately, success was only achieved with the reaction of the
very hindered cyclic carbene IPr and ‘‘GaI’’ in toluene.
Considerable gallium metal deposition was observed in this
reaction and upon workup a good yield of the novel salt 7
resulted (Scheme 1). It is interesting that the nature of this
product is different to that of the neutral complex [In2-
Br4(IMes)2], but it seems likely that the imidazolium proton
of the cation was abstracted from the solvent as this reac-
tion is entirely reproducible in good yield, even when it is
carried out under strictly anhydrous conditions. The fact
that the anion of 7 contains only one coordinated carbene
ligand, as opposed to the two cyclic carbene ligands in [In2-
Br4(IMes)2], could be due to the greater bulk of the cylic
carbene IPr and a lesser covalent radius of the metal atom
in the former complex. It is also worth noting here that the
formulation of ‘‘GaI’’ has been proposed to be [Ga]2[Ga2I6]
based on Raman spectroscopic studies.[11] It is not incon-
ceivable that the anion of 7 could be formed by displace-
ment of one iodide ligand from the [Ga2I6]2Ϫ dianion of
such a compound. The 1H and 13C NMR spectra of 7 show
two sets of resonances which integrate in a 1:1 ratio and
were assigned to the imidazolium cation and the cyclic car-
bene IPr coordinated to a gallium centre. The distinction
between the two sets of resonances can be confidently made
as the imidazolium cation has recently been structurally and
spectroscopically characterised in the salt [IPrH][InBr4].[12]
The fact that sharp resonances were observed for both the
imidazolium and carbene moieties over a range of tempera-
tures suggests that the carbene ligand is strongly coordi-
nated to the gallium centre and there is no carbene/imidazo-
lium exchange occurring in this complex.
Scheme 1. Preparation of complexes 2Ϫ8
Reaction of the sterically less hindered cyclic carbene
:CN(Me)C(Me)C(Me)N(Me) (IMe) with ‘‘GaI’’ also re-
sulted in considerable gallium metal deposition, but only an
inseparable mixture of unknown products formed. In con-
trast, the reaction of the same cyclic carbene with InCl af-
forded the unusual oxo-bridged dimer [{InCl(IMe)2}2(µ-
Cl)(µ-O)][Cl] (8) in low yield (Scheme 1). This probably
forms due to the presence of adventitious oxygen in the
reaction mixture. Neither compound 8 nor any other prod-
uct could be isolated or identified when the reaction was
repeated under strictly anaerobic conditions. The spectro-
scopic data for 8 fully support its proposed structure; most
notably an InϪO stretch was observed at 335 cmϪ1 in its
infrared spectrum. This is in good agreement with other
examples in the literature.[13] No OϪH stretching absorp-
tion could be seen in the same spectrum, which provides
good evidence that there is no proton attached to the bridg-
ing oxygen centre.
The infrared spectra of all the amine complexes 2Ϫ4 dis-
play strong, broad NϪH stretching absorptions in the ex-
pected region but the amine proton resonance was only ob-
1
served in the H NMR spectrum of 3. The infrared spectra
of 2Ϫ4 exhibit bands at 450, 453 and 409 cmϪ1 which have
been assigned to GaϪN stretches from comparisons with
related alkylgalliumϪamine adducts.[8] The infrared spectra
of the secondary phosphane complexes 5 and 6 show PϪH
stretching bands at 2258 and 2353 cmϪ1, respectively. In
addition, their 31P NMR spectra reveal doublet resonances
1
with JPH coupling constants (5: 359 Hz; 6: 351 Hz) of a
significantly greater magnitude than those recorded for the
free phosphanes (PCy2H: 193 Hz; PtBu2H: 198 Hz). A simi-
lar trend has been reported for secondary phosphane ad-
ducts of trialkylgallium compounds.[9] It should be noted
that the reactions of several primary phosphanes, thiols and
bulky alcohols with ‘‘GaI’’ were carried out but no tractable
products could be obtained.
Structural Studies
Crystals of 2Ϫ8 were grown from toluene solutions and
the molecular structures of these compounds are depicted
N-Heterocyclic Carbene Reactions
Due to the now well-known analogy between phosphanes in Figures 1Ϫ7 (see also Tables 1 and 2). The five amine
and NHCs,[10] and given our previous preparation of [In2- and phosphane complexes of Ga2I4, viz. 2Ϫ6, display simi-
Br4(IMes)2], it was thought worthwhile to examine the reac- lar structural features in that their gallium centres all pos-
tivity of a series of NHC ligands with ‘‘GaI’’. Unfortu- sess distorted tetrahedral environments and each
Eur. J. Inorg. Chem. 2003, 2446Ϫ2451
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R. J. Baker, H. Bettentrup, C. Jones
FULL PAPER
[Ga2I4(L)2] molecule exhibits a staggered conformation task. The complexes in the present study do not, however,
with respect to the GaϪGa bond. A previous report has appear to follow any trends (see Table 1). For example, the
suggested that some geometrical parameters of complexes GaϪGa bond lengths in 2Ϫ6 are all very similar
˚
of the type [Ga2I4(L)2] can be used to gauge the relative [2.4243(9)Ϫ2.459 A (av.)] despite incorporating a range of
Lewis basicity of the donor ligands L with respect to the amine and phosphane ligands of variable basicity. In ad-
GaII centres in these complexes.[3] Specifically, differences dition, the IϪGaϪI angles in all complexes do not vary to
in galliumϪgallium bond lengths and trends towards more any great degree. We believe, however, that a better indi-
sp2-like geometries at the gallium centres, as evidenced by cation of the degree of sp2 character at each gallium centre
an increase in the IϪGaϪI angle, were employed for this can be gained from the sum of the IϪGaϪI and GaϪGaϪI
angles around them. In the five complexes studied here,
these values range from 332.1 to 336.4°. Again, this range
is too narrow to draw any firm conclusions on the basicity
of the ligands involved. The GaϪP bond lengths in com-
plexes 5 and 6 are similar to those in [Ga2I4(PEt3)2] (2.413
[3]
˚
˚
A) and [Ga2I4(PPh3)2] (2.445 A), whilst the GaϪN dis-
tances in compounds 2Ϫ4 are close to those in the only
known tertiary amine complex of gallium() iodide, namely
[4]
˚
[Ga2I4(NEt3)2] (2.094 A av.).
Figure 1. Molecular structure of 2; symmetry operation: Ј Ϫx ϩ
3/2, Ϫy Ϫ 1/2, z
Figure 4. Molecular structure of 5; symmetry operation: Ј Ϫx ϩ 2,
Ϫy, Ϫz ϩ 2
Figure 2. Molecular structure of 3; symmetry operation: Ј Ϫx ϩ 1,
Ϫy ϩ 1, z
Figure 5. Molecular structure of 6; symmetry operation: Ј Ϫx ϩ 1,
y, Ϫz ϩ 3/2
The molecular structure of the anion of 7 is depicted in
Figure 6. Both gallium centres have distorted tetrahedral
coordination environments and the GaϪGa distance
˚
[2.4739(12) A] is slightly longer than any in 2Ϫ6, and signif-
icantly longer than previously seen in the [Ga2I6]2Ϫ dianion,
[14]
˚
for example 2.413 A in [PPh3H][Ga2I6].
All the GaϪI
distances are similar to those in related systems, for example
[PPh3H][Ga2I6], although the GaϪI bond lengths of the
Figure 3. Molecular structure of 4; symmetry operation: Ј Ϫx, Ϫy
ϩ 1, Ϫz
2448
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Eur. J. Inorg. Chem. 2003, 2446Ϫ2451

Reactivity of Amines, Phosphanes and N-Heterocyclic Carbenes towards Group-13 Metal(I) Halides
FULL PAPER
Figure 6. Structure of the anionic component of 7; selected bond
Figure 7. Structure of the cationic component of 8; selected bond
˚
˚
lengths [A] and angles [°]: Ga(1)ϪGa(2) 2.4739(12), Ga(1)ϪI(1)
lengths [A] and angles [°]: In(1)ϪCl(1) 2.823(2), In(1)ϪCl(2)
2.5977(11), Ga(1)ϪI(2) 2.5819(10), Ga(2)ϪI(3) 2.6178(11),
Ga(2)ϪI(4) 2.6153(12), Ga(2)ϪI(5) 2.6068(12), Ga(1)ϪC(1)
2.070(7), N(1)ϪC(1) 1.361(9), N(1)ϪC(2) 1.372(9), C(2)ϪC(3)
2.592(2), In(1)ϪO(1) 2.174(7), In(1)ϪC(1) 2.233(7), In(1)ϪC(8)
2.235(7), In(2)ϪCl(1) 2.921(2), In(2)ϪCl(3) 2.542(2), In(2)ϪO(1)
2.172(7),
In(2)ϪC(15)
2.221(7),
In(2)ϪC(22)
2.218(8);
78.54(5),
1.345(11),
N(2)ϪC(3)
1.384(9),
N(2)ϪC(1)
1.358(9);
In(1)ϪO(1)ϪIn(2)
113.6(3),
In(1)ϪCl(1)ϪIn(2)
C(1)ϪGa(1)ϪGa(2) 117.54(18), C(1)ϪGa(1)ϪI(2) 109.81(19),
Ga(2)ϪGa(1)ϪI(2) 108.64(4), C(1)ϪGa(1)ϪI(1) 107.09(19),
Cl(2)ϪIn(1)ϪC(1) 94.64(18), Cl(2)ϪIn(1)ϪC(8) 91.51(19),
C(1)ϪIn(1)ϪC(8)
O(1)ϪIn(1)ϪC(1)
109.2(3),
120.0(3),
Cl(1)ϪIn(1)ϪCl(2)
O(1)ϪIn(1)ϪC(8)
172.16(6),
128.7(3),
Ga(2)ϪGa(1)ϪI(1)
Ga(1)ϪGa(2)ϪI(5) 120.13(4), Ga(1)ϪGa(2)ϪI(4) 111.00(5),
109.57(4),
I(2)ϪGa(1)ϪI(1)
103.24(4),
C(15)ϪIn(2)ϪC(22) 107.9(3), C(15)ϪIn(2)ϪCl(3) 95.46(19),
I(5)ϪGa(2)ϪI(4)
I(5)ϪGa(2)ϪI(3)
C(1)ϪN(1)ϪC(2)
C(2)ϪN(1)ϪC(4)
N(2)ϪC(1)ϪN(1)
105.40(4),
103.80(4),
111.1(6),
121.0(6),
104.7(6),
Ga(1)ϪGa(2)ϪI(3)
I(4)ϪGa(2)ϪI(3)
C(1)ϪN(1)ϪC(4)
C(1)ϪN(2)ϪC(3)
C(3)ϪC(2)ϪN(1)
112.29(4),
102.53(4),
127.0(6),
110.1(6),
106.7(7),
C(22)ϪIn(2)ϪCl(3)
92.6(2),
C(15)ϪIn(2)ϪO(1)
121.3(3),
C(15)ϪIn(2)ϪCl(1) 87.00(19), C(22)ϪIn(2)ϪO(1) 126.9(3),
C(22)ϪIn(2)ϪCl(1)
N(1)ϪC(1)ϪN(2)
81.1(2),
105.5(6),
Cl(1)ϪIn(2)ϪCl(3)
N(3)ϪC(8)ϪN(4)
173.72(7),
105.6(6),
N(5)ϪC(15)ϪN(6) 103.9(6), N(7)ϪC(22)ϪN(8) 104.9(6)
C(2)ϪC(3)ϪN(2) 107.4(7)
˚
Table 1. Selected bond lengths [A] and angles [°] for compounds 2Ϫ6
Compound
2
3
4
5
6
GaϪN/P
GaϪGa
GaϪI
2.020(4)
2.036(3)
2.083 av.
2.459 av.
2.586 av.
2.424(2)
2.4459(10)
2.4448(9)
2.5935(6)
2.5745(6)
2.4287(10)
2.5951(7)
2.5727(7)
2.4243(9)
2.5769(7)
2.5731(8)
2.4370(15)
2.5924(10)
2.5755(11)
IϪGaϪI
ΣIϪGaϪI and GaϪGaϪI
108.17(2)
335.8
107.965(1)
334.8
104.8 av.
334.8 av.
110.07(3)
336.4
104.91(2)
332.1
GaI3 fragment are slightly longer than those associated with with the indium centres. The acuteness of the InϪClϪIn
the carbene-coordinated gallium centre. The metric param- angle [78.54(5)°] adds weight to this proposal. This situ-
eters of the coordinated NHC ligand are similar to those ation most likely arises from the fact that each indium cen-
seen in other group-13 complexes, such as [InBr3(IPr)],[12] tre is coordinated by two highly nucleophilic NHC ligands,
and the GaϪC interaction is similar to those in which weaken the bonds from the other ligands to these
˚
NHCϪGa() complexes, cf. 2.077
A
(av.) in metal centres.
[GaH3{CN(iPr)C2Me2N(iPr)}].[15]
The crystal structure of the cationic component of 8 is
shown in Figure 7. The indium atoms both have distorted
trigonal-bipyramidal coordination environments whilst the
Conclusions
four-membered
In2ClO
ring
is
essentially
flat
In conclusion, we have shown that ‘‘GaI’’ reacts with a
(InϪClϪInϪO torsion angle 0.7°). The average InϪC bond range of primary and secondary amine and secondary
˚
of 2.227 A is similar to that found in the complex [In- phosphane ligands to give adducts of the type [Ga2I4(L)2]
[16]
˚
H3(IMes)] [2.250(10) A]. Interestingly, both the terminal (L ϭ Lewis base), which are formed by disproportionation
˚
˚
and bridging InϪCl bonds (2.567 A av. and 2.872 A av., reactions. A range of these complexes have been crystallo-
respectively) are considerably longer than the norms for graphically characterised, as have the products from the re-
[17]
˚
such bonds (2.45 and 2.59 A)
and indeed, the bridging lated reactions of N-heterocyclic carbenes with either
ClϪ ligand can be thought of as only having an interaction ‘‘GaI’’ or InCl. We believe that complexes of the type 2Ϫ6
Eur. J. Inorg. Chem. 2003, 2446Ϫ2451
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R. J. Baker, H. Bettentrup, C. Jones
FULL PAPER
Table 2. Crystallographic data for compounds 2Ϫ8
2
3
4
5
6·C7H8
7·(C7H8)4
8·CH2Cl2
Empirical formula
Formula mass
Temp. [K]
C12H26Ga2I4N2
845.39
293(2)
C8H22Ga2I4N2
793.32
150(2)
C24H46Ga2I4N2
1009.67
298(2)
C24H46Ga2I4P2
1043.59
150(2)
C23H46Ga2I4P2
1031.58
150(2)
C82H105Ga2I5N4
1920.64
150(2)
C29H50Cl6In2N8O
969.11
150(2)
Crystal system
Space group
orthorhombic
Pccn
20.992(4)
8.0880(16)
13.222(3)
90
2244.9(8)
4
2.501
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/n
orthorhombic
Pbcn
18.548(4)
14.559(3)
13.125(3)
90
3544.3(12)
4
1.933
monoclinic
P21/c
monoclinic
P21/n
˚
a [A]
9.2720(19
10.325(2)
10.928(2)
94.22(3)
1043.3(4)
2
19.688(4)
9.858(2)
17.111(3)
90.11(3)
3321.0(11)
4
9.6600(19)
14.478(3)
13.154(3)
107.98(3)
1749.8(6)
2
17.216(3)
27.028(5)
17.801(4)
92.48(3)
8275(3)
4
12.774(3)
25.620(5)
13.118(3)
92.49(3)
4289.1(15)
4
˚
b [A]
˚
c [A]
β [°]
V [A ]
3
˚
Z
Dcalcd. [g/cm3]
2.525
8.484
2.019
5.356
1.981
5.171
1.542
2.559
1.501
1.481
µ [mmϪ1
]
7.896
5.105
Unique reflections
Observed reflections
[I Ͼ 2σ(I)]
2567
2111
2381
2093
5837
4067
3193
2784
4061
3533
14469
11598
7503
6168
R (obsd. data)
Rw (wR2) (all data)
0.0303
0.0636
0.0300
0.0693
0.0411
0.0906
0.0452
0.1003
0.0306
0.0720
0.0598
0.1364
0.0679
0.1522
vacuo and placement at Ϫ30 °C overnight yielded colourless crys-
tals of 2 (0.38 g, 36%). M.p. 255Ϫ258 °C (dec). 1H NMR
(400 MHz, C6D6, 300 K): δ ϭ 1.16 (m, 8 H, CH2), 1.69 (m, 8 H,
CH2), 2.03 (m, 4 H, CH2), 2.94 (m, 2 H, CH) ppm; NH2 resonance
not observed. 13C NMR (100.6 MHz, C6D6, 300 K): δ ϭ 35.6, 25.4,
24.9 (CH2), 51.4 (CH) ppm. IR (Nujol): ν˜ ϭ 3427 (br.), 1940 (br.),
1463 (sh), 1377 (sh), 1260 (sh), 1087 (br.), 1017 (br.), 956 (m), 888
(w), 799 (s), 723 (m), 584 (w), 534 (w), 467 (m), 450 (m), 377 (br.),
331 (m). MS APCI: m/z (%) ϭ 83 (100) [Cyϩ], 100 (40) [CyNH3ϩ],
268 (10) [Ga2Iϩ].
have significant potential for use as precursors in the forma-
tion of heterocyclic and cage compounds containing low
oxidation state Ga centres. To this end we are currently ex-
amining their reactivity towards a number of strong bases
in the expectation that HI abstraction will occur. Our efforts
in this area will be reported in a forthcoming publication.
Experimental Details
[Ga2I4(NtBuH2)2] (3): Yield 48%. M.p. 161Ϫ164 °C (dec). 1H NMR
(400 MHz, C6D6, 300 K): δ ϭ 1.17 (s, 18 H, tBu), 8.52 (br., 4 H,
NH2) ppm. 13C NMR (100.6 MHz, C6D6, 300 K): δ ϭ 27.8
[C(CH3)3], 53.1 [C(CH3)3] ppm. IR (Nujol): ν˜ ϭ 3236 (sh), 3176
(sh), 1554 (sh), 1463 (s), 1374 (s), 1277 (m), 1257 (m), 1197 (w),
1163 (m), 1101 (br.), 1016 (w), 820 (m), 801 (m), 733 (m), 681 (m),
596 (br.), 453 (br.), 371 (w) cmϪ1. MS FAB: m/z (%) ϭ 57 (100)
[tBuϩ], 74 (24) [tBuNH3ϩ].
General Remarks: All manipulations were carried out using stand-
ard Schlenk and glove-box techniques under high-purity argon.
Toluene was distilled from potassium whilst CH2Cl2 was distilled
from CaH2 then freeze/thaw-degassed prior to use. 1H and 13C
NMR spectra were recorded with a Bruker DXP400 spectrometer
1
and are referenced to the residual H or 13C resonances of the sol-
vent used. 31P NMR spectra were recorded with a Jeol Eclipse 300
spectrometer and are referenced to 85% H3PO4. APCI mass spectra
were recorded using a VG Fisons Platform II instrument. FAB
mass spectra were recorded by the EPSRC National Mass Spectro-
metric Service at Swansea University. IR spectra were recorded
using a Nicolet 510 FT-IR spectrometer as Nujol mulls between
CsI plates. Melting points were determined in sealed glass capillar-
ies under argon and are uncorrected. Reproducible microanalyses
were not obtained on any of the crystallographically characterised
complexes because of the presence of solvent of crystallisation and/
or the air-sensitive nature of these complexes. In all cases, however,
the spectroscopic data pointed to the bulk materials having a purity
[Ga2I4(NCy2H)2] (4): Yield 95%. M.p. 215Ϫ217 °C (dec). 1H NMR
(400 MHz, C6D6, 300 K): δ ϭ 1.05 (m, 16 H, CH2), 1.70 (m, 16 H,
CH2), 1.95 (m, 8 H, CH2), 3.30 (m, 4 H, CH) ppm; NH resonance
not observed. 13C NMR (100.6 MHz, C6D6, 300 K): δ ϭ 23.8, 23.9,
32.2 (CH2), 57.7 (CH) ppm. IR (Nujol): ν˜ ϭ 3427 (w), 1453 (s),
1376 (s), 1260 (m), 1162 (w), 1122 (m), 1081 (s), 1028 (m), 960 (m),
916 (w), 895 (w), 800 (m), 715 (m), 409 (br.) cmϪ1 . MS FAB: m/z
(%) ϭ 182 (100) [Cy2NHϩ], 648 (8) [Ga2I2].
[Ga2I4(PCy2H)2] (5): Yield 41%. M.p. 78Ϫ81 °C (dec). 1H NMR
of greater than 98%. ‘‘GaI’’ was synthesised by a variation of the (400 MHz, C6D6, 300 K): δ ϭ 1.10 (m, 16 H, CH2), 1.62 (m, 16 H,
1
literature method[7] as were the cyclic carbenes IPr[18] and IMe.[19]
All other chemicals were obtained commercially and used as re-
ceived. Compounds 2Ϫ6 were prepared by the general procedure
outlined below.
CH2), 2.09 (m, 8 H, CH2), 2.59 (m, 4 H, CH), 4.45 (d, JPϪH ϭ
359 Hz, 2 H, PH) ppm. 13C NMR (100.6 MHz, C6D6, 300 K): δ ϭ
25.2 (d, JP,C ϭ 13 Hz, CH2), 27.1 (d, 3JP,C ϭ 12 Hz, CH2), 29.8 (d,
4JP,C ϭ 8 Hz, CH2), 32.2 (d, JP,C ϭ 18 Hz, CH) ppm. 31P{1H}
1
NMR (101.6 MHz, C6D6, 300 K): δ ϭ Ϫ27.5 (s) ppm. IR (Nujol):
ν˜ ϭ 2258 (m), 1448 (s), 1377 (s), 1349 (w), 1327 (w), 1295 (m), 1264
(m), 1202 (w), 1180 (w), 1117 (br.), 1002 (br.), 888 (m), 854 (w),
[Ga2I4(NCyH2)2] (2): GaI was synthesised by sonicating Ga
(0.343 g, 4.92 mmol) and I2 (0.62 g, 2.45 mmol) in toluene (10 mL)
at 50 °C for approx. 2 h. The resulting green suspension was cooled
to Ϫ78 °C and a solution of NCyH2 (1.12 mL, 9.8 mmol) in tolu-
ene (5 mL) added to it over 5 min. The reaction mixture was
warmed to room temperature and stirred for 12 h to give a brown
solution and a precipitate of Ga metal. Filtration, concentration in
791 (m), 727 (w), 502 (br.), 381 (br.) cmϪ1 . MS FAB: m/z (%) ϭ
ϩ
197 (45) [PCy2H2
]
[Ga2I4(PtBu2H)2] (6): Yield 54%. M.p. 137Ϫ140 °C (dec). 1H NMR
3
(400 MHz, C6D6, 300 K): δ ϭ 1.26 (d, JPϪH ϭ 15 Hz, 36 H, tBu);
2450
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2003, 2446Ϫ2451

Reactivity of Amines, Phosphanes and N-Heterocyclic Carbenes towards Group-13 Metal(I) Halides
FULL PAPER
1
4.92 (d, JPϪH ϭ 351 Hz, 2 H, PH) ppm. 13C NMR (100.6 MHz,
included in calculated positions (riding model). The structure of 4
C6D6, 300 K): δ ϭ 21.2 [C(CH3)3], 53.1 (d, 1JP,C ϭ 10 Hz C(CH3)3] contains two crystallographically independent monomeric moieties
ppm. 31P{1H} NMR (101.6 MHz, C6D6, 300 K): δ ϭ Ϫ9.04 (s) in the asymmetric unit. The geometries of the dimeric units gener-
ppm. IR (Nujol): ν˜ ϭ 2353 (w), 1459 (s), 1376 (s), 1260 (m), 1162
ated from these are not significantly different and thus the ORTEP
(w), 1086 (m), 1021 (m), 936 (w), 870 (w), 803 (m), 727 (s), 694 diagram of only one is shown in Figure 3. The geometrical param-
(m), 555 (w), 462 (br.), 383 (br.), 323 (m) cmϪ1. MS FAB: m/z eters for 4 in Table 1 are, however, an average of those in the two
(%) ϭ 57 (100) [tBu], 793 (4) [Mϩ Ϫ PHtBu2].
molecules. Crystal data, details of data collections and refinement
are given in Table 2. The molecular structures of the complexes are
depicted in Figures 1Ϫ7 and show thermal ellipsoids set at the 30%
probability level. CCDC-203134 (2), -203135 (3), -203136 (4),
-203137 (5), -203138 (6), -203139 (7) and -203140 (8) contain the
supplementary crystallographic data for this paper. These data
can be obtained free of charge at www.ccdc.cam.ac.uk/conts/
retrieving.html [or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: (internat.)
ϩ 44-1223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
[Ga2I5(IPr)][IPrH] (7): GaI was synthesised by sonicating Ga
(0.125 g, 1.79 mmol) and I2 (0.22 g, 0.88 mmol) in toluene (10 mL)
at 50 °C for approx. 2 h. The resulting green suspension was cooled
to Ϫ78 °C and a solution of the cyclic carbene IPr (0.69 g,
1.79 mmol) in toluene (20 mL) added to it over 5 min. The reaction
mixture was warmed to room temperature and stirred for 12 h to
give a brown solution and a precipitate of Ga metal. Filtration,
concentration in vacuo and placement at Ϫ30 °C overnight yielded
1
colourless crystals of 7 (0.36 g, 42%). M.p. 238Ϫ242 °C (dec). H
3
NMR (400 MHz, CD2Cl2, 300 K): δ ϭ 1.10 (d, JHH ϭ 7 Hz, 12
3
H, CH3, cation), 1.21 (d, JH,H ϭ 7 Hz, 12 H, CH3, cation), 2.33
Acknowledgments
We gratefully acknowledge financial support from EPSRC (post-
doctoral fellowship for R. J. B.). Thanks also go to the EPSRC
Mass Spectrometry Service for the recording of FAB mass spectra.
[sept, 3JH,H ϭ 7 Hz, 4 H, CH(CH3)2, cation], 7.31 (d, 3JH,H ϭ 8 Hz,
4 H, m-CH, cation), 7.54 (t, 3JH,H ϭ 8 Hz, 2 H, p-CH, cation), 7.99
(s, 2 H, NC2H2N, cation), 8.42 (s, 1 H, NCHN, cation), 1.00 (d,
3
3JH,H ϭ 7 Hz, 12 H, CH3, anion), 1.36 (d, JH,H ϭ 7 Hz, 12 H,
CH3, anion), 2.68 [sept, 3JH,H ϭ 7 Hz, 4 H, CH(CH3)2, anion], 7.26
3
3
[1] [1a]
(d, JH,H ϭ 8 Hz, 4 H, m-CH, anion), 7.40 (t, JH,H ϭ 8 Hz, 2
H, p-CH, anion), 7.99 (s, 2 H, NC2H2N, anion) ppm. 13C NMR
(100.6 MHz, CD2Cl2, 300 K): δ ϭ 23.7, 25.7 (CH3, cation), 29.1
[C(CH3)2, cation], 124.9 (p-Ar, cation), 125.2 (m-Ar, cation), 132.4
(o-Ar, cation), 134.7 (ipso-Ar, cation), 145.1 (NCHN, cation), 145.7
(NC2H2N, cation), 23.9, 24.5 (CH3, anion), 28.8 [CH(CH3)2,
anion], 125.0 (p-Ar, anion), 127.0 (m-Ar, anion), 131.1 (o-Ar,
anion), 136.1 (ipso-Ar, anion), 146.1 (NC2H2N, anion) ppm. IR
(Nujol): ν˜ ϭ 2853 (br.), 1526 (m), 1455 (s), 1372 (s), 1260 (m), 1096
(s), 1055 (s), 1014 (s), 799 (s), 748 (m), 722 (m), 686 (w), 625 (w),
507 (w), 461 (w), 392 (br.), 305 (w), 289 (w), 245 (w) cmϪ1. MS
FAB: m/z (%) ϭ 389 (100) [IPrHϩ], 909 (61) [Ga2I3(IPr)ϩ]
H. Schnöckel, A. Schnepf, Adv. Organomet. Chem. 2001,
[1b]
47, 235Ϫ281.
G. Linti, H. Schnöckel, Coord. Chem. Rev.
2000, 206Ϫ207, 285Ϫ319 and references therein.
A. Schnepf, H. Schnöckel, Angew. Chem. Int. Ed. 2002, 41,
3533Ϫ3552, and references therein.
A. Schnepf, C. U. Doriat, E. Möllhausen, H. Schnöckel, Chem.
Commun. 1997, 2111Ϫ2112.
C. U. Doriat, M. Friesen, E. Baum, A. Ecker, H. Schnöckel,
Angew. Chem. Int. Ed. Engl. 1997, 36, 1969Ϫ1971.
B. Beagley, S. Godfrey, K. Kelly, S. Kungwankunakorn, C.
McAuliffe, R. Pritchard, Chem. Commun. 1996, 2179Ϫ2180.
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4016Ϫ4019.
[2]
[3]
[4]
[5]
[6]
[7]
[{InCl(IMe)2}2(µ-Cl)(µ-O)][Cl] (8): A solution of the cyclic carbene
IMe (0.66 g, 5.31 mmol) in toluene (10 mL) was added to a suspen-
sion of InCl (0.40 g, 2.66 mmol) in toluene (10 mL) held at Ϫ78
°C. The reaction mixture was stirred for 4 h during which time
indium metal deposition was observed. The resulting suspension
was filtered and volatiles removed from the filtrate in vacuo. The
yellow residue was extracted with CH2Cl2 (2 ϫ 5 mL). Concen-
tration to ca. 5 mL and the addition of toluene (2 mL) followed by
placement at Ϫ30 °C overnight yielded colourless crystals of 8
(0.37 g, 16%). M.p. 155Ϫ158 °C (dec). 1H NMR (400 MHz,
CD2Cl2, 300 K): δ ϭ 2.11 (s, 24 H, CMe), 3.64 (s, 24 H, NMe)
ppm. 13C NMR (100.6 MHz, CD2Cl2, 300 K): δ ϭ 8.14 (s, CMe),
34.62 (s, NMe) ppm. IR (Nujol): ν˜ ϭ 2919 (s), 2852 (s), 1634 (m),
1598 (m), 1588 (m), 1470 (sh), 1372 (s), 1250 (sh), 1081 (s), 1034
(s), 891 (w), 850 (w), 799 (m), 727 (sh), 688 (sh), 563 (m), 533 (m),
461 (sh), 392 (br.), 335 (s), 289 (w) cmϪ1. MS FAB: m/z (%) ϭ 125
(100) [IMeHϩ].
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
R. E. Douthwaite, M. L. H. Green, P. J. Silcock, P. T. Gomes,
Organometallics 2001, 20, 2611Ϫ2615, and references therein.
M. Kehrwald, W. Köstler, G. Linti, T. Blank, N. Wilberg, Or-
ganometallics 2001, 20, 860Ϫ867.
R. J. Baker, A. J. Davies, C. Jones, M. Kloth, J. Organomet.
Chem. 2002, 656, 203Ϫ210.
M. J. Zehe, D. A. Lynch, Jr, J. Benuel, D. K. Carlson, J. Phys.
Chem. 1979, 83, 656Ϫ664.
M. A. Khan, D. G. Tuck, M. J. Taylor, D. A. Rogers, J. Crys-
tallogr. Spectrosc. Res. 1986, 16, 895.
M. D. Francis, D. E. Hibbs, M. B. Hursthouse, C. Jones, N. A.
Smithies, J. Chem. Soc., Dalton Trans. 1998, 3249Ϫ3254.
C. D. Abernethy, M. L. Cole, C. Jones, Organometallics 2000,
19, 4852Ϫ4857.
As determined from a survey of the Cambridge Crystallo-
graphic Database.
L. Jafarpour, E. D. Stevens, S. P. Nolan, J. Organomet. Chem.
2000, 606, 49Ϫ54.
N. Kuhn, T. Kratz, Synthesis 1993, 561Ϫ564.
G. M. Sheldrick, SHELX-97, University of Göttingen, 1997.
Received February 4, 2003
Structure Determinations: Crystals of 2Ϫ8 suitable for X-ray struc-
tural determination were mounted in silicone oil. Crystallographic
measurements were made using a Nonius Kappa CCD dif-
fractometer. The structures were solved by direct methods and re-
fined on F2 by full-matrix least squares (SHELX97)[20] using all
unique data. All non-hydrogen atoms are anisotropic with H atoms
[19]
[20]
Eur. J. Inorg. Chem. 2003, 2446Ϫ2451
www.eurjic.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2451