Syntheses and structures of the heterometallic complexes [{MeIn(μ-PCy)}2(μ-PCy)]2(Li · Et2O)4, [Me2In(PhMes)2]-[Li(TMEDA)2] +

Article abstract of DOI:10.1016/j.ica.2005.12.029

The reaction of CyPHLi (Cy = cyclohexyl) with InMe₃ in Et₂O gives the heterometallic cage [{MeIn(μ-PCy)}₂(μ-PCy)]₂(Li · Et₂O)₄ (1), containing the heterometallic tetraanion [{MeIn (μ - PCy)

Full text of DOI:10.1016/j.ica.2005.12.029

Inorganica Chimica Acta 360 (2007) 1266–1273
www.elsevier.com/locate/ica
Syntheses and structures of the heterometallic complexes
[{MeIn(l-PCy)}2(l-PCy)]2(Li ÆEt2O)4, [Me2In(PhMes)2]ꢀ
[Li(TMEDA)2]+ and [Me2(PHMes)2In]ꢀ[K(PMDETA)2]+
[Cy = cyclohexyl, Mes = 2,4,6-Me3C6H2, TMEDA = (Me2NCH2)2,
PMDETA = (Me2NCH2CH2)2NMe]
a
a,
a
b
Isabel Fanjul , Felipe Garcıa *, Richard A. Kowenicki , Marta E.G. Mosquera ,
´
a
a,
*
Mary McPartlin , Dominic S. Wright
a
Chemistry Department, Cambridge University, Lensfield Road, Cambridge CB2 1EW, UK
Departamento de Quı´mica Inorga´nica, Universidad de Alcala´, Campus Universitario, Crta Madrid-Barcelona, Km 33,600, 28871, Spain
b
Received 14 November 2005; accepted 11 December 2005
Available online 17 February 2006
Dedicated to Prof. M. F. Lappert.
Abstract
The reaction of CyPHLi (Cy = cyclohexyl) with InMe3 in Et2O gives the heterometallic cage [{MeIn(l-PCy)}2(l-PCy)]2(Li Æ Et2O)4
(1), containing the heterometallic tetraanion ½fMeInðl-PCyÞg2ðl-PCyÞꢁ24ꢀ. In contrast, similar reactions of InMe3 with MesPHM
(M = Li, K) in the presence of the Lewis bases TMEDA and PMDETA give [Me2In(PhMes)2In]ꢀ[Li(TMEDA)2]+ (2) and
[Me2(PHMes)2In]ꢀ[K(PMDETA)2]+ (3), respectively. The formation of [Me2(PHMes)2In]ꢀ anions in these complexes provides key evi-
dence of the mechanism of formation of the metallocyclic tetraanion of 1.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Indium; Phosphorus; X-ray
1. Introduction
decomposes at 30–40 ꢁC into Zintl compounds containing
3ꢀ
the Sb7 anion along with the cyclo-phosphane [CyP]4
A major focus of our current work has been the develop-
ment of new ligand systems containing p-block metals [1].
We have recently employed the step-wise metallation of
primary phosphines with alkali metal organometallics fol-
lowed by reactions with Group 15 metal dimethylamido
compounds in the preparation of a variety of heterometallic
phosphinidene compounds. For example, the reaction of
[2,3]. This ‘cage-to-alloy’ reaction proceeds via cyclic anions
of the type [(RP)nE]ꢀ [4,5], and is driven thermodynamically
by the formation of P–P bonds (the strongest homonuclear
Group 15 bond) [2,3]. The importance of this new type of
reaction is that it provides the potential means by which a
host of materials can be deposited from solution at low tem-
perature. An important aim in more recent studies, has there-
fore been the extension of this synthetic methodology to
Group 13 and Group 14 analogues, particularly with a view
to developing structural and electronic relationships within
p-block element imido and phosphinidene compounds. We
recently reported the synthesis of [{MeAl(PPh)3Li4}4(l4–
Cl)]ꢀ Æ Li+, containing the [MeAl(PPh)3]4ꢀ tetraanion [6]
n
CyPH2 with BuLi followed by further deprotonation with
Sb(NMe2)3 gives the heterometallic cage [{Sb(PCy)3}2Li6]Æ
6Me2NH, containing the [Sb(PCy)3]3ꢀ trianion, which
*
Corresponding authors. Tel.: +44 1233 763122; fax: +44 1223 336362.
´
E-mail address: fg230@cam.ac.uk (F. Garcıa).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.12.029

I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
1267
(Fig. 1(c)), which is valence-isoelectronic with Group 14 and
15 trianions of the type [E(E0R)3]33ꢀꢀ (E = As, Sb; E0 = N, P)
ETA)2]+ (3), which provide key evidence on the likely
mechanism of formation of 1.
[7] (Fig. 1(a)) and [R0Si(NR)3]
(Fig. 1(b)) [8–14]. In
addition, we have prepared the heterometallic complex
2. Experimental
[{MeAl(l-PMes)(PMes)}2Li4]2. 7thf, containing a ½MeAl-
4ꢀ
ðl-PMesÞðPMesÞ2ꢁ2 tetraanion (Mes = 2,4,6–Me3–C6H2)
2.1. General experimental
(Fig. 1(f)) [15], which is valence-isoelectronic with Group
14 and 15 anions of the type ½R0Siðl-NRÞðNRÞꢁ2
Compounds 1–3 are air- and moisture-sensitive. They
were handled on a vacuum line using standard inert-atmo-
sphere techniques [27] and under dry/oxygen-free argon.
Toluene and thf were dried by distillation over sodium/
benzophenone prior to the reactions. Cyclohexylphosphine
was was acquired from Strem, and mesityl phosphine
(MesPH2) was prepared using the literature procedure
[28]. TMEDA and PMDETA was dried by distillation over
Na metal and was stored under argon over molecular sieve
2ꢀ
2ꢀ
(Fig. 1(e)) and ½Eðl-NRÞðNRÞꢁ2
(E = P, As, Sb, Bi)
(Fig. 1(d)) [16–22].
Here we report the synthesis of [{MeIn(l-PCy)}2
(l-PCy)]2(Li Æ Et2O)4 (1), containing a ½fMeInðl-PCyÞg2
4ꢀ
ðl-PCyÞꢁ2 tetraanion which is valence-isoelectronic with
the metallocyclic Group 14 and 15 species [{P(l-NR)}2
(l-NR)]2 (R = tBu and iPr) (Fig. 2(a)) [23,24] and
4ꢀ
½fSnðl-PRÞg2ðl-PRÞꢁ2
(R = tBu and Cy) (Fig. 2(b))
˚
[25]. Complex 1 contains the first heavy Group 13 counter-
(4 A). InMe3 was prepared by the reaction of InCl3 with
part of the previously reported Al(III) tetraanion
MeLi in ether, and purified by distillation [29]. This reagent
was used as a standardised solution in ether. The products
were isolated and characterized with the aid of an argon-
filled glove box fitted with a Belle Technology O2 and
4ꢀ
½fMeAlðl-PRÞg2ðl-PRÞꢁ2 (R = Cy) (Fig. 2(c)) [26]. In
addition, we report the syntheses of [Me2(PHMes)2In]ꢀ
[Li(TMEDA)2]+ (2) and [Me2(PHMes)2In]ꢀ[K(PMD-
(b)
(c)
(a)
3-
3-
R´
Me
Al
3-
E
Si
RE'
E'R
RN
NR
PhP
PPh
E'R
NR
PPh
(f)
(e)
RN
(d)
4-
4-
R
Mes
2-
R
NR
MesP
PMes
Me
RN
NR
N
N
P
P
N
Si
Si
Al
Al
M
M
N
R´
R´
Me
R
Mes
R
E= Group 15 element
E'= N, P
Fig. 1. Series of structurally and electronically related Group 13, Group 14 and Group 15 anions.
(a)
(b)
(c)
4-
4-
R
R
R
Me
P
Me
P
N
N
N
N
P
P
P
P
P
P
Sn
Sn
Al
Al
Al
R
R
R
P
R
R
R
N
N
R
R
P
R
R
P
P
P
P
P
P
Sn
Sn
Al
Me
Me
R
R
R
R= Cy, tBu
R= iPr, tBu
R= Cy
Fig. 2. Groups 13–15 valence-isoelectronic and isostructural macrocyles related to the anion in 1.

1268
I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
H2O internal recirculation system. Elemental analyses were
performed by first sealing the samples under argon in air-
tight aluminium boats (1–2 mg) and C, H and N content
was analysed using an Exeter Analytical CE-440 elemental
analyser. P analysis was carried out by spectrophotometric
added MesPH2 (0.424 g, 0.7 mL, 3.0 mmol). The reaction
mixture was stirred at ꢀ78 ꢁC for 20 min and then warmed
to room temperature and stirred for a further 45 min, pro-
ducing a red suspension. This mixture was cooled again to
ꢀ78 ꢁC and InMe3 (1.5 mmol, 1.5 mL, 1 mol Lꢀ1 in ether)
in toluene (35 mL) was added. The subsequent reaction at
ꢀ78 ꢁC for 20 min and then at room temperature for a fur-
ther 16 h, produced a light-yellow suspension. Thf (10 mL)
and PMDETA (3.0 mmol, 0.62 mL) were added, the reac-
tion mixture was filtered and the filtrate was reduced in vol-
ume (to ca. 30 mL). Storage at ꢀ15 ꢁC for 48 h gave
colourless crystalline blocks of 3. Yield, 0.60 g (48%, based
on In). IR (Nujol, NaCl, m/cmꢀ1), major bands at 2995s,
1
means. H, 13C and 31P NMR spectra were recorded on a
Bruker DPX 500 MHz spectrometer in dry d6-benzene or
d6-toluene (for variable-temperature studies). The solvent
resonances were used as the internal reference standards
1
for H NMR spectroscopic studies, and 85% H3PO4/D2O
was employed as the external reference standard for 31P
NMR spectroscopic work.
Synthesis of 1; to a stirred solution of CyPH2 (3.0 mmol,
n
1
0.43 mL) in toluene (20 mL) at ꢀ78 ꢁC, was added BuLi
2854s, 2323, 1461s, 1376, 1261. H NMR (500.2 MHz, d/
(3.3 mmol, 2.06 mL, 1.6 mol Lꢀ1 in hexanes). The reaction
mixture was stirred at ꢀ78 ꢁC for 20 min and then warmed
to room temperature and stirred for a further 45 min,
affording a yellow suspension. This mixture was again
cooled to ꢀ78 ꢁC, and InMe3 (1.0 mL, 1.0 mol Lꢀ1 in
ether, 1.0 mmol) in toluene (35.0 mL) was added. The reac-
tion mixture was stirred at ꢀ78 ꢁC for 20 min and then
warmed to room temperature and stirred overnight. The
reaction mixture was filtered and the filtrate was reduced
in volume (to ca. 30 mL). Storage at ꢀ15 ꢁC for 48 h gave
ppm, d6-benzene, +25 ꢁC), 7.26 (s., Mes C–H, 4H), 3.92
(br.s., PH, 2H), 2.72 (s., o-CH3, 12H), 2.64 (s., m-CH3,
6H), 2.32–2.19 (overlapping multiplets, PMDETA). 31P
NMR (161.9 MHz, d/ppm, d6-benzene, +25 ꢁC), ꢀ167.3
(br.s.), ꢀ168.5 (br.s.). Anal. Calc. for 3: C, 55.8; H, 9.2;
N, 10.1. Found: C, 54.1; H, 8.8; N, 10.0%.
X-ray crystallography on 1, 2 toluene and 3; crystals of 1,
2 toluene and 3 were mounted directly from solution under
argon using an inert perfluorohydrocarbon oil which pro-
tects them from atmospheric oxygen and moisture [30].
X-ray intensity data were collected using a Nonius Kappa
CCD diffractometer and were solved by direct methods and
refined by full-matrix least-squares on F2 [31]. In 1, the car-
bon and oxygen atoms of the Et2O ligand associated with
O(1W) are disordered over two sites. There is also some
conformational disorder of one of the cyclohexyl groups
[at three of the carbon atoms, C(64), C(65), C(66)]. In 2,
the phosphorus atom P(1) is disordered over two 50:50
occupancy sites [P(1) and P(10)], which were allowed to
refine freely. No disorder is observed in the structure of
3. The H-atoms attached to the P centres in 2 and 3 were
located directly. These atoms were all refined freely, apart
from those attached to the two disordered phosphorus
atoms P(1) and P(10) which were constrained geometrically.
1
yellow crystals of 1. Yield, 0.20 g (52%, based on In). H
NMR (500.2 MHz, d/ppm, d6-benzene, +25 ꢁC), 2.1–0.5
(overlapping multiplet, total 106 H, total Et2O and Cy),
0.40 (s., In–CH3, 12H). 31P NMR (161.9 MHz, d/ppm,
d6-benzene, +25 ꢁC), ꢀ117.8 (bs.) ꢀ152.0 (br.s.). Anal.
Calc. for 1: C, 44.0; H, 7.8. Found: C, 43.9; H, 7.5%.
Synthesis of 2; to a stirred solution of solution of
MesPH2 (3 mmol, 0.7 mL) in toluene (20 mL) at ꢀ78 ꢁC,
n
was added BuLi (3.3 mmol, 2.06 mL, 1.6 mol Lꢀ1 in hex-
anes). The reaction mixture was stirred at ꢀ78 ꢁC for
20 min and then warmed to room temperature and stirred
for a further 45 min, affording a yellow suspension. This
mixture was cooled again to ꢀ78 ꢁC and InMe3 (1.5 mmol,
1.5 mL, 1 mol Lꢀ1 in ether) in toluene (35.0 mL) was
added. The reaction mixture was stirred for 20 min and
then warmed to room temperature and stirred overnight.
The mixture was filtered and the filtrate was reduced in vol-
ume (to ca. 30 mL). Storage at ꢀ15 ꢁC for 48 h gave yellow
crystals of the toluene solvate 2 toluene. Placing crystals
under vacuum (15 min, 10–2 atm.) leads to complete desol-
vation, giving an amorphous powder of 2 (with no toluene
present). The following data refer to this unsolvated mate-
rial. Yield, 0.60 g (57%, based on In). IR (Nujol, NaCl, m/
3. Results and discussion
In earlier studies we had observed that the reactions of
the Sn(II) and Al(III) cubanes [SnNtBu]4 and [MeAlN-
Mes]4 with CyPHLi (1:6 equivalents) in thf give the hetero-
metallic complexes [{Sn(l-PCy)2}2(l-PCy)]2[Li(thf)]4 and
[{MeAl(l-PCy)2}2(l-PCy)]2[Li(thf)]4,
containing
the
4ꢀ
½fSnðl-PCyÞ2g2ðl-PCyÞꢁ
[25a] and ½fMeAlðl-PCyÞ2g2-
2
1
cmꢀ1), major bands at 2996s, 2844s, 1470s, 1368, 1242. H
ðl-PCyÞꢁ2 [26] tetraanions (shown in Fig. 2(b) and (c)).
We also found that Sn(II) complexes containing this type
of tetraanion could be obtained directly from reactions of
4ꢀ
NMR (500.2 MHz, d/ppm, d6-benzene, +25 ꢁC), 7.26 (s.,
aryl C–H, 4H), 3.92 (br.s., PH, 2H), 2.72 (s., o-CH3,
12H), 2.64 (s., p-CH3, 6H), 2.25 (s., 4H, CH2CH2,
TMEDA), 2.09 (s., 12H, Me2N, TMEDA). 31P NMR
(161.9 MHz, d/ppm, d6-benzene, +25 ꢁC), ꢀ165.89 (br.s.),
ꢀ167.75 (br.s.). Anal. Calc. for 2: C, 55.8; H, 9.2; N,
10.1. Found: C, 54.1; H, 8.8; N, 10.0%.
t
Sn(NMe2)2 with RPHLi (R = Cy, Bu) in thf, (most effec-
tively) using a 1:3 stoichiometric ratio of the reagent
[25b]. A primary goal in the current study was to develop
a simple synthetic approach to similar metallocyclic frame-
works for heavier Group 13 metals [specifically In(III)]. We
find that the 1:3 stoichiometric reaction of InMe3 with
CyPHLi in Et2O/toluene gives the heterometallic complex
Synthesis of 3; to a stirred solution of PhCH2K
(3.5 mmol, 0.455 g) in toluene (20 mL) at ꢀ78 ꢁC was

I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
1269
[{MeIn(l-PCy)2}2(l-PCy)]2[Li(Et2O)]4 in 52% yield
(Scheme 1).
ion-separated, crystalline complexes [Me2(PHMes)2In]ꢀ
[Li(TMEDA)2]+ (2) and [Me2(PHMes)2In]ꢀ[K(PMD-
ETA)2]+ (3) were obtained in good yields, using the Lewis
base donors TMEDA and PMDETA to facilitate crystalli-
sation (Scheme 2). The mechanism involved in the forma-
tion of the [Me2(PHMes)2In]ꢀ anions of these complexes
is not understood at this stage.
In an attempt to extend this route to similar metallocy-
clic arrangements containing other alkali metal cations and
organic substituents (R), various alkali metal primary
phosphides [RPHM; M = alkali metal] were reacted with
InMe3 in the same 3:1 stoichiometric ratio as employed
in the synthesis of 1. In the cases of the reactions of Mes-
PHM [M = Li and K] with InMe3 (3:1 equivalents) the
Prior to the X-ray characterizations of 1, 2 and 3 they
were characterized by elemental and spectroscopic analy-
ses. Complex 1 shows a series of complicated overlapping
1
multiples in the region d 0.5–2.1 in its H NMR spectrum
at room temperature, corresponding the cyclohexyl groups
and ether ligands. The 31P NMR shows two very broad
singlets at d ꢀ117.8 and ꢀ152.0, which could not be
resolved at low temperature (down to ꢀ80 ꢁC). These are
assigned to the PCy groups within the [In(l-PCy)]2 dimer
units and those linking the dimeric rings into the metallo-
4-
Cy
Me
Me
Cy
P
P
In
In
OEt2
Et2O
Li
Li
Li
Et2O/toluene
P
Cy
3CyPHLi + Me3In
Cy
Et2O
P
4ꢀ
cyclic arrangement of the ½fMeInðl-PCyÞ2g2ðl-PCyÞꢁ2
Li
In
P
OEt2
tetraanion. It can be noted that for the Sn(II) systems
[{Sn(l-PR)}2(l-PR)]4ꢀ the appearance of the 31P NMR
spectrum is highly dependent on the organic group (R)
[25]. For R = Cy, distinct doublet and triplet multiplets
are observed for the two P-environments, whereas for
R = tBu (like 1) two broad resonances only could be
In
P
1
Me
Cy
Me
Cy
Scheme 1.
PHMes
In
-
RM
InMe3
2 x L
[ML2]+
3 MesPHM
3MesPH2
-RH
Me
Me
PHMes
M= Li; L= TMEDA (2)
M= K; L= PMDETA (3)
Scheme 2.
Table 1
Crystal data and refinements for [{MeIn(l-PCy)}2(l-PCy)]2(Li Æ Et2O)4 (1), [Me2(PHMes)2In]ꢀ[Li(TMEDA)2]+ (2 toluene) and
[Me2(PHMes)2In]ꢀ[K(2PMDETA)]+ (3)a
Compound
Fw
C56H118P6In4Li4O4 (1)
1528.36
C39H70InLiN4P2 (2) toluene
778.69
C38H76InKN6P2(3)
832.91
Crystal system
Space group
monoclinic
P2(1)/c
monoclinic
P2(1)/c
triclinic
ꢀ
P1
Unit cell dimensions
˚
a (A)
19.972(4)
20.013(4)
18.609(4)
18.729(4)
15.545(3)
15.437(3)
11.094(2)
11.713(2)
18.184(4)
85.18(3)
88.46(3)
85.88(3)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
92.09(3)
98.20(3)
3
˚
U (A )
7433(3)
1.390
4448.4(15)
0.631
2348.0(8)
0.690
l (Mo Ka) (mmꢀ1
)
Z
4
4
2
qcalc (Mg mꢀ3
)
1.366
1.163
1.178
Crystal size (mm)
0.18 · 0.12 · 0.12
49171
10 226 (0.053)
0.066, 0.154
0.078, 0.158
0.37 · 0.28 · 0.07
23686
5432 (0.074)
0.047, 0.108
0.086, 0.128
0.37 · 0.30 · 0.12
23051
10617 (0.041)
0.050, 0.078
0.086, 0.090
Reflections collected
Independent reflections (Rint
R1, wR2 (I > 2r(I))
R1, wR2 (all data)
a
)
˚
Data in common; k = 0.71073 A, T = 180(2)K for 1–3.

1270
I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
Table 2
bases TMEDA (in 2) and PMDETA (in 3). Unexpectedly,
the P–H protons in 2 and 3 appear as broad singlets, which
could not be resolved into the anticipated doublets even at
low temperature. 31P NMR spectra of 2 and 3 at room tem-
perature show broad singlets at ca. d ꢀ165 and ꢀ167 in
both. The spectra are essentially unchanged at low temper-
ature. This behaviour may suggest that the two P-environ-
ments in both complexes are rendered inequivalent by
restricted rotation of the sterically demanding Mes groups.
Having established the basic identities of the complexes,
they were subjected to X-ray structural analysis. Details of
the crystal data and refinements are collected in Table 1.
Table 2 lists selected bond lengths and angles for complex
1, while data for 2 and 3 is given in Table 3.
The low-temperature crystal structure of complex 1 shows
that it is the mixed-metal cage [{MeIn(l-PCy)}2-
(l-PCy)]2(Li Æ Et2O)4, consisting of a centrosymmetric, four-
teen-membered In4P6Li4 core (Fig. 3). This structure is clo-
sely related to that of the Sn(II) complexes [{Sn(l-PR)2}2
(l-PR)]2(Li Æ thf)4 Æ (R = Cy, tBu) [25] and the Al(III)
complex [{MeAl(l-PCy)2}2(l-PCy)]2(Li Æ thf)4 [26]. Crystals
of 1 contain two crystallographically-independent molecules
which are chemically identical (molecules A and B, Table 2).
The discussion of its structure will therefore involve the
Selected bond lengths and angels for complex on [{MeIn(l-PCy)}2(l-
PCy)]2(Li Æ Et2O)4 (1)
Molecule A
Molecule B
˚
Bond lengths (A)
In(1)–P(1)
In(1)–P(2)
In(1)–P(3A)
In(2)–P(1)
In(2)–P(2)
2.611(3)
2.588(3)
2.559(3)
2.598(3)
2.601(3)
2.560(3)
In(3)–P(5)
In(3)–P(4)
In(3)–P(6)
In(4)–P(4)
In(4)–P(5)
In(4)–P(6)
2.606(2)
2.587(3)
2.546(3)
2.595(3)
2.598(3)
2.557(3)
In(2)–P(3)
Molecule 1
Molecule 2
Bond angles (ꢁ)
P(1)–In(1)–P(2)
P(1)–In(1)–P(3A)
P(2)–In(1)–P(3A)
P(2)–In(2)–P(1)
P(2)–In(2)–P(3)
P(1)–In(2)–P(3)
In(1)–P(1)–In(2)
In(1)–P(2)–In(2)
In(2)–P(3)–In(1A)
95.92(9)
108.36(9)
97.4(10)
95.91(9)
109.44(9)
99.63(8)
83.1(1)
P(4)–In(4)–P(5)
P(6)–In(3)–P(4)
P(6)–In(3)–P(5)
P(5)–In(3)–P(4)
P(6)–In(4)–P(5)
P(6)–In(4)–P(4)
In(4)–P(4)–In(3)
In(3)–P(5)–In(4)
In(3)–P(6)–In(4)
97.57(8)
112.29(9)
98.92(9)
97.55(8)
112.64(9)
98.33(9)
81.69(8)
81.99(8)
116.9(1)
83.46(8)
112.5(1)
1
observed irrespective of the temperature. The H NMR
spectra of 2 and 3 are largely as expected, showing reso-
nances for the Mes groups and the presence of the Lewis
Table 3
Selected bond length and angles for [Me2(PHMes)2In]ꢀ[Li(TMEDA)2]+ (2Å toluene) and [Me2(PHMes)2In]ꢀ[K(PMDETA)2]+ (3)
2
3
2
3
˚
Bond lengths (A)
In(1)–P(1)
In(1)–P(2)
mean 2.608(3)a
2.606(2)
2.602(1)
2.597(1)
In(1)–C
M–N range
2.179(6)–2.198(6)
2.11(1)–2.14(1)
2.190(4)–2.195(4)
2.838(3)–3.011(3)
Bond angles (ꢁ)
C–In(1)–C
P(1)–In(1)–P(2)
a
118.4(2)
109.51(16)
105.66(4)
P–In(1)–C range
N–In(1)–N range
101.2(2)–114.6(2)a
86.2(4)–126.2(5)
107.66(11)–114.02(11)
62.08(1)–151.54(9)
mean 106.7a
Mean values are quoted for the bond lengths and angles associated with the two disordered sites of the phosphorus atom P(1) and P(10).
(a)
(b)
Fig. 3. (a) Metallocyclic structure of the ½fInðl-PCyÞg2ðl-PCyÞꢁ24ꢀtetraanion and (b) Solid-state structure of 1 (molecule A is shown). H-atoms and
disorder have been omitted for clarity.

I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
1271
range or average of the bond lengths and angles found in
both of these molecules of 1 in the crystal lattice. Molecules
of 1 are formed by the association of the indium phosphinid-
involved are similar to those observed in a number of pre-
viously reported lithium phosphide complexes (range 2.38–
˚
2.78 A) and are typical of bonds between anionic P centres
and Li+ [32]. The Li+ cations are each solvated by a mole-
ꢀ4
ene tetraanion ½fInðl-PCyÞg2ðl-PCyÞꢁ2 (Fig. 3(a)) (con-
sisting of two [{In(l-PCy)]2 ring units linked by two l-PCy
groups) with four ether-solvated Li+ cations (Fig. 3(b)).
The In–P bonds within 1 vary in the range 2.546(3)–
cule of ether, producing a pseudo-tetrahedral geometry for
the Li+ ions (Li–O av. 1.95 A, angle at Li av. 108.7ꢁ).
˚
The low-temperature X-ray studies of 2Å toluene (Fig. 4)
and 3 (Fig. 5) show that both are ion-separated species in
the solid state. Significantly, both of the complexes contain
the same [Me2In(PHMes)2]ꢀ anion. The [Me2In(PHMes)2]ꢀ
anions of 2 and 3 have distorted tetrahedral In(III) centres
(angles at In av. 109.5ꢁ and 108.6ꢁ in 2 and 3, respectively).
˚
˚
2.611(3) A (av. 2.58 A), and are in the range of In–P
distances found for previously reported In–P bonded com-
˚
pounds (av. 2.60 A) [35]. The In(III) centres adopt tetrahe-
dral geometries (angle at In av. 109.0ꢁ). The four Li+
cations are coordinated by phosphorus atoms within the
dimer units of the metallocyclic tetraanion and by the
two phosphorus atoms that bridge the dimers together
˚
˚
The In–P bond distances (av. 2.61 A in 2, av. 2.60 A in 3)
are in the range found previously for this type of compound
[32]. However, 2 and 3 are relatively rare examples of
˚
[P–Li range 2.59(1)–2.90(2) A]. The P–Li distances
Fig. 4. Structure of 2. H-atoms and disorder of the cyclohexyl groups and at P(1) have been omitted for clarity (as has toluene salvation in the lattice).
Fig. 5. Structure of 3. H-atoms have been omitted for clarity.

1272
I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
4-
Me
Me
PR
R
P
RHP
Me
PHR
In
Me
Me
In
In
In
In
In
R
P
P
R
2x
2x
In
RP
RHP
RHP
-2CH4
-2RPH2
R
P
P
R
Me
P
R
Me
Me
Scheme 3. Proposed mechanism of formation of the anion of 1 via a [Me2InPHR]ꢀ anion intermediate.
complexes containing In(III) phosphide anions, other exam-
ples of this type being the ion-separated complexes
½ðPh2PÞ Inꢁꢀ ½LiðthfÞꢁ þ [33] and [(2,3,4,5-tetramethylphosp-
Cambridge CB2 1EZ, UK (fax: +44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
4
4
holyl-P)2InCl2]ꢀK+(18-crown-6) [34] and the ion-paired
Acknowledgements
complex {[(iPr3SiPH)4In]ꢀK+} [35]. The Li+ and K+ cat-
1
ions in 2 and 3 are bis-coordinated by the TMEDA and
PMDETA ligands, resulting in distorted four- and six-
coordinate geometries for these ions, respectively. The
[Li(TMEDA)2]+ and [K(PMDETA)2]+ cationsin these com-
plexes are unremarkable.
We gratefully acknowledge The EPSRC (F.G., M.McP.,
D.S.W.), the E.U. (Erasmus Program, I.F.), The Royal
Society (M.E.G. Mosquera) and The Cambridge European
Trust (F.G.) for financial support.
References
4. Closing remarks
[1] M.A. Beswick, D.S. Wright, Coordin. Chem. Rev. 176 (1998) 373.
[2] M.A. Beswick, J.M. Goodman, C.N. Harmer, A.D. Hopkins, M.A.
Paver, P.R. Raithby, A.E. Wheatley, D.S. Wright, J. Chem. Soc.,
Chem. Commun. (1997) 1897.
[3] M.A. Beswick, C. Harmes, A.D. Hopkins, M. McPartlin, D.S.
Wright, Science 281 (1998) 1500.
[4] A. Bashall, N. Choi, A.D. Hopkins, M.E.G. Mosquera, M. McPart-
lin, P.R. Raithby, A. Rothenberger, D. Stalke, A.E. Wheatley, D.S.
Wright, J. Chem. Soc., Chem. Commun. (1998) 2485.
[5] A. Bashall, M.A. Beswick, N. Choi, A.D. Hopkins, S.J. Kidd, Y.G.
Lawson, M.E.G. Mosquera, M. McPartlin, P.R. Raithby, A.E.
Whealey, J.A. Wood, D.S. Wright, J. Chem. Soc., Dalton Trans.
(2000) 479.
Compounds 2 and 3 potentially provide information
about the mechanism of formation of 1. Scheme 3 shows
a proposed mechanism in which condensation of two of
the [Me2In(PHR)2]ꢀ anions (accompanied by the elimina-
tion of two molecules of methane) results in the formation
of the intermediate dimer [MeIn(PHR)(l-PR)]2 (A). The
condensation of two molecules of A (with the elimination
of two molecules of RPH2) would result in the macrocyclic
structure of 1. A similar mechanism was proposed by us
previously for the synthesis of the Sn(II) anions
[6] M.J. Duer, F. Garcia, R.A. Kowenicki, V. Naseri, M. McPartlin,
M.L. Stead, R.S. Stein, D.S. Wright, Angew. Chem., Int. Ed. Engl.
44 (2005) 5729.
4ꢀ
½fSnðl-PRÞg2ðl-PRÞꢁ2
[36], in which the macrocyclic
arrangements appear to stem from the association of two
molecules of the dimeric intermediate [Sn(PHR)(l-PR)]2
(related to A). Thus, the current study of In(III) com-
pounds provides some further indication that the reaction
pathways found for Groups 14 and 15 phosphides already
are related to the mechanisms found for Group 13 counter-
parts. Further studies will be aimed at establishing closer
structural and mechanistic links between the chemistry of
p block metal phosphides, particularly at the use of Group
13 phosphinidene complexes in the formation of P–P and
metal–metal bonded compounds.
[7] M.A. Beswick, N. Choi, C.N. Harmer, A.D. Hopkins, M. McPartlin,
M.A. Paver, P.R. Raithby, A. Steiner, M. Tombul, D.S. Wright,
Inorg. Chem. 37 (1998) 2177.
[8] D.J. Brauer, H. Burger, G.R. Liewald, J. Wilke, J. Organomet.
Chem. 287 (1985) 305.
[9] D.J. Brauer, H. Burger, G.R. Liewald, J. Wilke, J. Organomet.
Chem. 308 (1986) 119.
[10] M. Veith, A. Spaniol, J. Pohlmann, F. Gross, V. Huch, Chem. Ber.
126 (1993) 2625.
[11] M. Driess, G. Hutler, N. Knopf, H. Pritzokow, L. Zuolnai, Angew.
Chem., Int. Ed. Engl. 34 (1995) 316.
[12] G. Huber, A. Jockisch, H. Schimidbauer, Z. Naturforsch, B, Chem.
Sci. 54 (1999) 8.
[13] J.K. Brask, T. Chivers, M. Parvez, Inorg. Chem. 39 (2000) 2505.
[14] P. Kosse, E. PoPowski, M. Veith, V. Huch, Chem. Ber. 127 (1999)
2103.
5. Supplementary material
Crystallographic data for the structural analyses of 1, 2Å
toluene and 3 have been deposited with the Cambridge
Crystallographic Data Centre, CCDC Nos. 289009–
289011. Copies of this information can be obtained free
of charge from The Director, CCDC, 12, Union Road,
´
[15] F. Garcıa, R. Haigh, M. McPartlin, D.S. Wright, J. Chem. Soc.,
Chem. Commun. (2003) 2052.
[16] M. Veith, F. Goffing, V. Huch, Chem. Ber. 121 (1988) 943.
[17] R.A. Alton, D. Barr, A.J. Edwards, M.A. Paver, P.R. Raithby, M.-
A. Rennie, C.A. Russell, D.S. Wright, J. Chem. Soc., Chem.
Commun. (1994) 1481.

I. Fanjul et al. / Inorganica Chimica Acta 360 (2007) 1266–1273
1273
[18] P. Kosse, E. Popowski, M. Veith, V. Huch, Chem. Ber. 127 (1994)
2103.
[27] D.F. Shriver, M.A. Drezdon, The Manipulation of Air-Sensitive
Compounds, second ed., Wiley, New York, 1986.
[19] A. Bashall, M.A. Beswick, C.N. Harmer, A.D. Hopkins, M.
McPartlin, M.A. Paver, P.R. Raithby, D.S. Wright, J. Chem. Soc.,
Dalton Trans. (1998) 1389.
[20] L. Grocholl, L. Stahl, R.J. Staples, Inorg. Chem. 37 (1998) 5036.
[21] M. Veith, F. Goffing, V. Huch, Z. Naturforsch. B 43 (1998) 846.
[22] V. Klingebiel, B. Tecklenburg, M. Noltemeyer, D. Schmidt-Base, R.
Herbst-Irmer, Z. Naturforsch. B 53 (1998) 315.
[28] T. Oshikawa, M. Yamashita, Chem. Ind. (1985) 126.
[29] D.F. Foster, S.A. Rushworth, D.J. Cole Hamilton, R. Cafferty, J.
Harrison, P. Paukes, J. Chem. Soc., Dalton Trans. (1988) 7.
[30] T. Kottke, D. Stalke, J. Appl. Crystallogr. 26 (1993) 615.
[31] G.M. Sheldrick, SHELXL-97, Go¨ttingen, Germany, 1997.
[32] Cambridge Structural Data Base and Visualizing Crystal Structures
(January 2004), I.J. Bruno, J.C. Cole, P.R. Edgington, M. Kessler,
C.F. Macrae, P. McCabe, J. Pearson, R. Taylor, Acta Cryst. 1B58
[23] O.J. Scherer, K. Andres, C. Kruger, Y.-H. Tsay, G. Wo¨lmersha¨user,
¨
˚
˚
˚
Angew. Chem. Int. Ed. Engl. 19 (1980) 571.
[24] J.K. Brask, T. Chivers, M. Krahn, M. Parvez, Inorg. Chem. 38
(1999) 290.
(2001) 389, In–P av. 2.60 A, In–P av. 2.640 A; range P–Li 2.38–2.78 A.
[33] C.J. Carrano, A.H. Cowley, D.M. Giolando, R.A. Jones, C.M.
Nunn, Inorg. Chem. 27 (1988) 2709.
[25] (a) R.E. Allen, M.A. Beswick, N.L. Cromhout, M.A. Paver, P.R.
Raithby, M. Trevithick, D.S. Wright, Chem. Commun. (1996) 1501;
(b) A.D. Bond, A. Hopkins, A. Rothenberger, A.D. Wood, D.S.
Wright, J. Chem. Soc., Chem. Commun. (2001) 525.
[26] R.E. Allan, M.A. Beswick, P.R. Raithby, A. Steiner, D.S. Wright, J.
Chem. Soc., Dalton Trans. (1996) 4153.
[34] T. Doughlas, K.H. Theopold, B.S. Haggerty, A.L. Rheingold,
Polyhedron 9 (1990) 329.
[35] M. Westerhausen, S. Weinrich, H. Piotrowski, Z. Naturforsch. B 56
(2001) 576.
´
[36] F. Garcıa, A.D. Hopkins, C.M. Pask, A.D. Woods, D.S. Wright, J.
Mater. Chem. (2004) 3093.