The unusual reactions of indium(I) trifluoromethanesulfonate with some first row metallocenes and the structure of indium(II) cyclopentadienide

Article abstract of DOI:10.1016/j.jorganchem.2005.03.028

The soluble reagent indium(I) trifluoromethanesulfonate, InOTf, does not appear to react or interact with ferrocene (Cp₂Fe, Cp = C ₅H₅) whereas cobaltocene reacts with InOTf to produce [Cp₂Co]⁺[OTf]^- and indium metal. Unexpectedly, the reaction of InOTf with manganocene results in the formation of the unprecedented salt [In(μ²,η⁵-Cp)In] ⁺[Cp₃In(μ²,η¹-Cp)InCp ₃]^-: a form of Cp₂In that is characterized by X-ray crystallography. Similarly, the reaction of InOTf with [Cp₂Fe]⁺[PF₆]^- produces Cp ₂Fe and In₄OTf₆ in addition to other products. The unusual structural features and the formation of the new indium-containing products are rationalized.

Full text of DOI:10.1016/j.jorganchem.2005.03.028

Journal of Organometallic Chemistry 690 (2005) 5090–5097
www.elsevier.com/locate/jorganchem
The unusual reactions of indium(I) trifluoromethanesulfonate
with some first row metallocenes and the structure of ‘‘indium(II)
cyclopentadienide’’
*
Christopher G. Andrews, Charles L.B. Macdonald
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ont., Canada N9B 3P4
Received 3 February 2005; received in revised form 16 March 2005; accepted 16 March 2005
Available online 4 May 2005
Abstract
The soluble reagent indium(I) trifluoromethanesulfonate, InOTf, does not appear to react or interact with ferrocene (Cp2Fe,
Cp = C5H5) whereas cobaltocene reacts with InOTf to produce [Cp2Co]+[OTf]ꢀ and indium metal. Unexpectedly, the reaction of
InOTf with manganocene results in the formation of the unprecedented salt [In(l2,g5-Cp)In]+[Cp3In(l2,g1-Cp)InCp3]ꢀ: a form
of ‘‘Cp2In’’ that is characterized by X-ray crystallography. Similarly, the reaction of InOTf with [Cp2Fe]+[PF6]ꢀ produces Cp2Fe
and ‘‘In4OTf6’’ in addition to other products. The unusual structural features and the formation of the new indium-containing prod-
ucts are rationalized.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Indium; Subvalent; Metallocenes; Main group; Redox chemistry
1. Introduction
Cp0E [1], as ligands for transition metal and main group
acceptors has been exploited significantly since the late
1990s for the synthesis of new catalysts or materials pre-
cursors [2,3].
The oxidation state of an element significantly affects
the structural features and reactivity of the compound in
which it is found. By definition, an element in a low oxi-
dation state has a greater number of electrons associated
with it than it would in a higher oxidation state; these
additional electrons can completely alter the chemistry
of compounds containing such centers. For example
the +3 oxidation state is the most stable for most of
the elements of group 13 (E) making neutral molecules
containing such elements behave as Lewis acids. In con-
trast, the relatively rare compounds that contain group
13 elements in the +1 oxidation state can behave either
as Lewis bases or Lewis acids, as illustrated in Scheme
1. The potential of using EI compounds, especially
cyclopentadienyl (C5R5, Cp0) compounds of the type
The full potential of the chemistry of compounds
containing group 13 elements in the +1 oxidation state
has not been realized, in part because of the lack of con-
venient starting materials other than certain organome-
tallic EI reagents [3,4]. Well-characterized oligomeric EI
halides for E = B, Al and Ga are prepared by gas-phase
reactions requiring a special apparatus and the materials
are often only meta-stable [5,6]. The oft-used compound
‘‘GaII’’ [7] has been shown to have neither the structure
nor the composition suggested by the indicated formula
[8]. In contrast to the lighter congeners, thallium(I) salts
are favored over their thallium(III) analogues because of
relativistic effects. For indium, simple halide salts of
both +1 and +3 oxidation states are available, however
the InI salts are insoluble in most common organic
solvents [4]. As a necessary starting point for our
*
Corresponding author. Tel.: +51925330003991; fax: +5199737098.
E-mail address: cmacd@uwindsor.ca (C.L.B. Macdonald).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.03.028

C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
5091
each In atom and thus render additional arene–In con-
tacts unnecessary. Such an interpretation is consistent
with the lack of arene complex formation or even arenes
of recrystallization when 1 is crystallized from toluene
[9].
D
R E
A
The reaction of InOTf with cobaltocene also proceeds
in a predictable fashion. When a solution of Cp2Co in
toluene is mixed with an equimolar solution of 1, the
deep purple color of the cobaltocene solution immedi-
ately changes to bright yellow and a fine grey precipitate
is formed. Removal of the precipitate by filtration gener-
ates a clear yellow filtrate from which yellow crystalline
material characterized as [Cp2Co]+[OTf]ꢀ, 3, is obtained
upon concentration. The grey precipitate was identified
as metallic In by its melting point thus the reaction is
readily understood as being the one-electron reduction
of InI to In0 with the concomitant oxidation of the CoII
center to CoIII. The high isolated yield of 3 suggests that
this reaction is essentially quantitative and thus may be
of preparative utility.
In contrast to the reactions with Cp2Fe and Cp2Co,
the reaction of manganocene and InOTf resulted in
the production of completely unexpected products. Stir-
ring an equimolar toluene solution of 1 with Cp2Mn
rapidly formed a bright yellow solution that fades with
time and a colorless precipitate. While the composition
of the extremely air-sensitive precipitate has yet to be
confirmed, concentration of the yellow solution results
in the formation of air-sensitive yellow crystals suitable
for analysis by X-ray diffraction. The crystals were iden-
tified as [In(l2,g5-Cp)In]+[Cp3In(l2,g1-Cp)InCp3]ꢀ, 4,
and the structure obtained from the crystallographic
experiment is shown in Fig. 1; pertinent metrical param-
eters are collected in Table 1.
Scheme 1.
investigation and exploitation of low oxidation state
group 13 chemistry, we synthesized the unusually solu-
ble indium(I) trifluoromethanesulfonate salt (indium(I)
triflate, InOSO2CF3, InOTf, 1) as an improved starting
material for such studies [9]. Herein, we report some un-
ique and unexpected reactivity that we have discovered
using this new reagent.
In 2002, Wagner [10] reported the unexpected isola-
tion of the coordination polymer 2 from the reaction
of ferrocene ((C5H5)2Fe, Cp2Fe) with GaCl3. The coor-
dination polymer almost certainly resulted from the
reduction of GaCl3 to Ga2Cl4, which disproportionates
to form [Ga]+[GaCl4]ꢀ in the presence of aromatic mol-
ecules (ferrocene, in this instance); each GaI center is
coordinated by two arenes to produce 2, as depicted in
Scheme 2. The behavior and structure of arene com-
plexes of GaI, InI and TlI have been examined and re-
viewed by Schmidbaur [11] and Tuck [4], among
others. In this context, we wished to investigate the pos-
sibility of using InOTf to obtain similar arene
complexes.
2. Results and discussion
The structure of 4 consists of inverse sandwich cations
of the type [In(l2,g5-Cp)In]+ and complex mono-anions
of the form [Cp3In(l2,g1-Cp)InCp3]ꢀ. The cyclopenta-
dienyl ring in the cation (labeled with C(51)) sits on an
inversion center (X(1)) at the fractional coordinates
(0.25, 0.75, 0.5) and is extremely disordered. The indium
With the initial hope of obtaining a coordination
polymer analogous to 2, toluene solutions containing
equimolar amounts of 1 and Cp2Fe were mixed. The
1
color of the solution remained orange and H, 13C and
19F NMR spectra did not reveal any changes from the
starting materials. Removal of all of the volatile sub-
stances under vacuum yielded a mixture of colorless
and orange crystals which were identified as the starting
materials. That the reaction did not form an arene-com-
plex coordination polymer is likely a consequence of the
stability of the InOTf structure, which contains numer-
ous In–O contacts that fill the coordination sphere of
˚
atoms in the cation are found at a distance of 2.659(3) A
from the inversion center and have significantly longer
contacts with the p-systems of the Cp rings on adjacent
anions; the closest In(1) to centroid distances are 3.050,
˚
3.178 and 3.669 A and the centroids of the four closest
Cp rings are arranged in a roughly tetrahedral manner
about the In(1) atom. While the [In(l2,g5-Cp)In]+ cation
Ga
Ga2Cl4
Cp
Cp
Cp2Fe
Cp2Fe
GaCl4
Fe
Fe
GaCl3
or
2n
- [Cp2Fe]+[GaCl4]−
Cp
Cp
Ga
n
Ga GaCl4
2
Scheme 2.

5092
C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
Fig. 1. Ball and stick representation of [In(l2,g5-Cp)In]+[Cp3In(l2,g1-
Cp)InCp3]ꢀ, 4.
Table 1
Selected metrical parameters for 4
Fig. 2. Thermal ellipsoid plot (30% probability surface) of the anion in
4.
Parameter
Parameter
C(11)–In(2)
C(11)–C(15)
C(11)–C(12)
C(12)–C(13)
C(13)–C(14)
C(14)–C(15)
C(21)–In(2)
C(21)–C(22)
C(21)–C(25)
C(22)–C(23)
C(23)–C(24)
In(1)–C(5n)cent
2.253(3)
1.424(5)
1.447(5)
1.349(6)
1.390(6)
1.344(5)
2.276(3)
1.416(5)
1.436(5)
1.358(6)
1.391(6)
2.659(3)
C(31)–In(2)
C(31)–C(32)
C(31)–C(35)
C(32)–C(33)
C(33)–C(34)
C(34)–C(35)
C(41)–In(2)
C(41)–C(43)
C(41)–C(42)
C(42)–C(42)#1
C(43)–C(41)#1
2.280(3)
1.420(5)
1.429(5)
1.348(6)
1.380(7)
1.357(6)
2.431(3)
1.399(4)
1.423(5)
1.343(7)
1.399(4)
to those reported for the coordination polymeric neutral
InIII compound InCp3, 5 [16]. In particular, the In–C
distances to the r-bonded Cp ligands of 2.253(3)–
˚
2.280(3) A in 4 are only marginally longer than the
˚
2.229(4) A in 5 and the 2.431(3) A In–C distance to
˚
the bridging Cp is somewhat shorter than the
˚
2.482(4) A in 5.
The empirical formula for 4 is C10H10In and thus the
compound is an isomeric form of ‘‘Cp2In’’. The struc-
tures of the ions in 4 are clearly consistent with the salt
being described as a mixed valence indium species con-
taining InI and InIII centers in the solid state. In solu-
tion, however, only one signal is observed in both the
1H and 13C NMR spectra (even at ꢀ90 °C) indicating
that all of the Cp rings are equivalent on the NMR time-
scale and thus an alternative structural arrangement is
present in solution. Such behavior is thus reminiscent
of the chemistry of the InII halides [4] and it is important
to note that the chemical shifts observed for 4 are virtu-
ally identical to those reported by Beachley et al. [16] for
the mixture of CpIn and Cp3In. In that case, it was pos-
tulated that the mechanism that renders each of the Cp
groups equivalent may involve the formation of the InII
intermediate Cp2In–InCp2. However, since it has been
demonstrated that the presence of cyclopentadienyl
groups tend to destabilize such EIIEII arrangements
(for E = B, Al) in favor of possible EIEIII valence iso-
mers [17–19], and given the structure of the anion in 4
found in the solid state, we propose that perhaps a more
likely mechanism involves the formation of ions of [InI]+
and [Cp4InIII]ꢀ. The relationship between the various
likely valence isomers of 4 is outlined in Scheme 3. We
believe that the rearrangement of the simple InIInIII salt
into the inverse-sandwich cation and bridging anion
may aid in the solid state packing of the salt by provid-
ing cations and anions that are more similar in size; such
a process appears to require less rearrangement for the
In(2)–C(11)–H(11)
In(2)–C(21)–H(21)
94(3)
100(2)
In(2)–C(31)–H(31)
In(2)–C(41)–H(41)
97(3)
92(2)
˚
Bond distances are reported in (A) and angles are reported in (°).
has not been reported previously, the metrical parame-
ters in the ion are consistent with those expected on the
basis of those observed in the related InI-containing spe-
cies. In particular, the InI-centroid distance in 4 lies al-
most exactly halfway between the short InI-centroid
contacts (2.609 and 2.629 A, respectively) and long con-
˚
tacts (2.771 and 2.667 A, respectively) in the two struc-
tures reported previously for the neutral coordination
polymer CpIn [12,13]. Furthermore, the InI-centroid dis-
tance in 4 is significantly longer than those (2.435–
˚
2
5
+
˚
2.528 A) reported for the cations [In(l ,g -C5Me5)In]
that bear the more electron donating pentamethylcyclo-
pentadienyl substituent [14,15].
The structure of the anion in 4 is unique and is de-
picted in Fig. 2. The anion consists of two indium atoms
that are each coordinated by three r-bonded Cp rings
and that are linked to each other by a bridging bis-g1-
Cp ring situated on a crystallographic 2 axis. The loca-
tions of the hydrogen atoms on the ipso-carbon atoms
of the r-bonded groups, as well as each of the hydrogen
atoms on the bridging ring, were used in conjunction
with the metrical parameters of the carbon skeletons
to assign the hapticities of the rings. While the anion
is without precedent, the structural features are similar

C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
5093
simple ionic isomer than for either the donor–acceptor
or the covalent isomers.
with the OTf groups; and (3) the coordination sphere
of the ‘‘external’’ InI ions is capped by the interactions
with the toluene molecules.
While the process through which 4 is formed from
Cp2Mn and 1 requires further elucidation, the reaction
clearly entails the cleavage of Cp rings from the metallo-
cene in addition to the oxidation of some of the indi-
um(I) centers. We are currently investigating the
possibility of making 4 from In2Cl4 however our
attempts to date have not been successful thus it appears
as if the best current method of its preparation is the
reaction of CpIn with Cp3In [16].
Although there are many instances of InIII coordi-
nated by octahedral arrays of oxygen atoms in the Cam-
bridge Structural Database (CSD) [20], the tri-anion in 6
is unique and appears to be one of the only examples
containing six triflate anions coordinated to any kind
of metal atom listed in the CSD. Examination of the
metrical parameters in the anion show that the distances
Because of the unexpected nature of the reaction of
InOTf with manganocene, we examined the reaction of
our indium(I) source with a salt containing a metalloce-
nium cation isoelectronic with manganocene, namely
the ferricenium salt [Cp2Fe]+[PF6]ꢀ. The reaction of an
equimolar amount of 1 with [Cp2Fe]+[PF6]ꢀ results in
the formation of an intense blue solution. Filtration of
the reaction mixture and slow concentration of the fil-
trate yielded a mixture of colorless and orange crystal-
line materials. The orange crystals were identified as
ferrocene and the colorless crystals were characterized
as the mixed-valent salt ½Inꢁþ½InðOTfÞ ꢁꢀ3, 6. Although
3
6
the other reaction product(s) remain unidentified, a pos-
sible balanced equation for the reaction is:
6InOTf þ 2½Cp Feꢁþ½PF6ꢁꢀ
2
Fig. 3. Ball and stick representation of the components of 6.
! ½Inꢁþ½InðOTfÞ ꢁꢀ3 þ 2Cp Fe þ 2\½Inꢁþ½PF6ꢁꢀ" ð1Þ
2
3
6
Table 2
The unique components of the structure of the indium
‘‘subtriflate’’ 6 are depicted in Fig. 3 and important met-
rical parameters are collected in Table 2. The formula
unit of the structure contains three distinct indium envi-
ronments: there is a distorted octahedral [In(OTf)6]ꢀ3
anion labeled In(1); there is an InI cation labeled
In(3) that is also coordinated by a roughly octahedral
array of O atoms from the triflate groups; and there
are two InI cations (labeled In(2)) that are g6-coordi-
nated by the toluene molecules in the structure and have
close contacts with some of the O atoms from the triflate
groups. The crystalline arrangement, as illustrated in
Fig. 4, can be rationalized in the following manner:
(1) the InIII octahedra are linked to one another by the
InI ions to form alternating InI–InIII chains along the
crystallographic c axis; (2) the remaining InI ions are at-
tached to the alternating chain through close contacts
þ
ꢀ3
6
˚
Selected bond distances in (A) for ½Inꢁ ½InðOTfÞ ꢁ ꢂ 2 toluene, 6 Æ 2
3
toluene
Parameter
In(1)–O(11)
Distance
2.113(4)
Parameter
Distance
S(1)–O(11)
S(1)–O(12)
S(1)–O(13)
S(2)–O(21)
S(2)–O(22)
S(2)–O(23)
S(3)–O(31)
S(3)–O(32)
S(3)–O(33)
1.457(5)
1.422(6)
1.405(7)
1.451(5)
1.429(6)
1.421(6)
1.462(5)
1.414(6)
1.412(7)
In(1)–O(21)
In(1)–O(31)
2.126(5)
2.121(4)
In(3)–O(13)
In(3)–O(33)
2.880(7)
2.920(7)
In(3)–O(23)
2.902(7)
In(2)–O(12)
In(2)–O(32)
In(2)–C(2n)cent
2.705(6)
2.847(6)
2.998(7)
In(2)–O(22)
2.770(5)
In(2)–C(3n)cent
2.983(10)
Cp
Cp
Cp
Cp
Cp In In Cp
Cp
Cp
Cp
Cp
Cp
In Cp In
Cp In Cp In Cp
Cp Cp
Cp In Cp
Cp
2
In
In In
InI-InIII donor-acceptor
InII-InII
InI-InIII ionic alternatives
Scheme 3.

5094
C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
(a)
(b)
Fig. 4. Crystalline structure of 6 Æ 2 toluene (a) shows the alternating chain of InIII and InI centers and (b) shows the location of the InI Æ toluene
fragments around the chain.
between In(1) and the nearest O atoms, which range
III
from 2.113(4) to 2.126(5) A, are typical of In –O inter-
tances reported for [In(mesitylene)2]+ by Schmidbaur
et al. [22].
˚
actions; the average In–O distance in the CSD is around
˚
˚
0.73 A, respectively [21]. Furthermore, the bonding
While the identities of all of the by-products in the
reaction that generates 6 have yet to be established,
the isolation of Cp2Fe and the composition of 6 suggest
that a plausible process for the reaction almost certainly
initially involves the oxidation of InOTf to In2OTf4 by
the FeIII to FeII couple. As suggested in Scheme 4, we
surmise that the InII compound would rearrange to
the ionic InIInIII alternative in the toluene solution
and the interaction of the salt with two additional equiv-
alents of the InOTf starting material would yield 6. We
are currently endeavoring to synthesize 6 by the direct
reaction of 3 equivalents of InOTf and one equivalent
of InOTf3.
In conclusion, our initial examination of some of the
chemistry of InOTf with some first row metallocenes
has yielded some surprising results. In particular, while
the reactions of 1 with 18-electron and 19-electron spe-
cies are predictable, the reactions with the 17-electron
metallocenes result in the oxidation of the InI center
and the formation of products with unprecedented
structures. It appears that the nature of the oxidized
or partially oxidized products in both 4 and 6 is readily
understood in the context of the relative stabilities of
the possible valence isomeric forms. In particular, the
putative InIIInII products appear to be less stable than
the alternative InIInIII products under the reaction con-
ditions in this investigation. The most obvious differ-
ence between the reactions that produced 4 and 6 is
2.14 A and the covalent radii for In and O are 1.44 and
within the triflate ions appears to be somewhat more
localized than delocalized in the SO3 framework in the
sense that each anion has one longer S–O bond to the
O(n1) atoms that are bonded to the In(1) atom and
the two remaining S–O bonds are significantly shorter.
The coordination environments around the indium(I)
atoms within the chain are also approximately octahe-
dral however the shortest In(3)–O distances, which
˚
range from 2.880(7) to 2.920(7) A, are significantly
longer than those to the indium(III) center. In fact, while
these InI–O distances do fall within the sum of the van
˚
˚
der Waals radii for In (1.93 A) and O (1.52 A), all of
the distances are significantly longer than sum of the
covalent radii for the elements or the sum of the ionic
I
ꢀII
˚
˚
radii estimated for In (1.04 A) and O (1.40 A) [21].
The coordination environment around the indium(I)
ions external to the chain are less symmetric than those
of the other indium centers. Each of the ions labeled
In(2) has three In–O contacts ranging from 2.705(6) to
˚
2.847(6) A which are, again, significantly longer than
the distance predicted for typical single bonds between
these elements. The coordination sphere of In(2) also in-
cludes an g6-toluene molecule; the distance from the
˚
ring centroid to In(2) is around 2.983(10) A which is
˚
only somewhat longer than the 2.83 and 2.89 A dis-

C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
5095
In2OTf4
[Cp2Fe]+
- Cp2Fe
3
2 InOTf
toluene
3 In
+ InOTf6
InOTf
or
6
In InOTf4
Scheme 4.
the cleavage of the cyclopentadienyl rings from mang-
anocene and the retention of the Cp ligands in the ferr-
ocenium system.
3.2.2. Synthesis of [In(l2,g5-Cp)In]+[Cp3In(l2,g1-Cp)-
InCp3]ꢀ, 4
Toluene (50 mL) was added to a solid mixture of In-
OTf (527 mg, 2.00 mmol) and Cp2Mn (372 mg,
2.01 mmol), to result in the immediate formation of a
yellow solution. The reaction mixture was left stirring
overnight after which a fluffy off-white precipitate and
small number of brown particles formed. The reaction
mixture was filtered using a fine frit, and the solvent re-
moved in vacuo to isolate the product as a light yellow
solid (112 mg, 0.46 mmol, 22.9% yield based on In). Sin-
gle crystals suitable for X-ray analysis are obtained by
the slow evaporation of a concentrated toluene solution
at room temperature. d.p. 124–127 °C. 1H NMR (C7H8,
300 MHz): d 5.89 (broad, s); (C6D6, 300 MHz): d 5.98
(broad, s). 13C NMR (C7H8, 300 MHz): d 105.8 (s).
3. Experimental
3.1. General methods
All work was carried out using standard inert-atmo-
sphere techniques. Manganocene, ferrocene and cobal-
tocene were purchased from Strem whereas
[Cp2Fe]+[PF6]ꢀ and all solvents were obtained from Al-
drich; all reagents were used without further purifica-
tion. Preparative methods for InOTf are described in a
preliminary communication [9]. Solvents were dried on
a series of Grubbsꢀ type columns and were degassed
prior to use [23]. Unless otherwise noted in the text,
NMR spectra were recorded at room temperature on a
Bruker Avance 300 MHz spectrometer. Chemical shifts
are reported in ppm, relative to external standards
3.2.3. Synthesis of In4OTf6, 6
Toluene (50 mL) was added to a solid mixture of In-
OTf (459 mg, 1.74 mmol) and [Cp2Fe]+[PF6]ꢀ (191 mg,
0.58 mmol), to form a deep blue solution, which became
yellow with a blue suspension after stirring under nitro-
gen overnight. The reaction mixture was filtered and
concentrated to produce colorless crystals characterized
as 6 Æ 2 toluene (23 mg, 0.02 mmol, 3.9% isolated crystal-
line yield based on In after washing 3 times with toluene;
the actual yield is considerably greater). d.p. 116–
119 °C. 19F NMR (CDCl3, 300 MHz): d ꢀ78.8 (s).
1
(SiMe4 for H and 13C, CFCl3 for 19F). Melting points
were obtained using an ElectrothermalÒ melting point
apparatus on samples sealed in glass capillaries under
dry nitrogen or argon. The high resolution ESI mass
spectra were recorded on a Micromass LCT time-
of-flight spectrometer from acetonitrile solutions in
‘‘lockmass’’ mode.
3.2. Specific procedures
3.3. Crystallography
3.2.1. Synthesis of [Cp2Co]+[OTf]ꢀ
In the dry N2 atmosphere of a VAC glovebox, each
crystal was selected and mounted in thin-walled glass
capillary tubes. These were subsequently flame-sealed
and glued to brass pins suitable for attachment to a
goniometer head. The data were collected using the
SMART [24] software on a Bruker APEX CCD diffrac-
tometer using a graphite monochromator with Mo Ka
The addition of a purple solution of Cp2Co (398 mg,
2.10 mmol) in dichloromethane to a colorless suspension
of InOTf (548 mg, 2.08 mmol) in the same solvent re-
sults in the immediate formation of a lemon yellow solu-
tion in which was suspended a fine grey powder of
metallic In. After filtration and rinsing of the metal with
fresh dichloromethane, the solvent was removed in va-
cuo to yield the product as a bright yellow solid
(633 mg, 1.87 mmol, 90.1% yield). Crystalline material
is obtained by the slow evaporation of a concentrated
CH2Cl2 solution. m.p. 330–331 °C. Low resolution mass
spectrometry supports the identities of both the
[Cp2Co]+ and [OTf]ꢀ ions. HRMS: Calcd. for
C10H10Co: 189.0114, found: 189.0110 (2.4 ppm). 1H
NMR (CD2Cl2, 300 MHz): d 5.77 (s). 13C NMR
(CD2Cl2, 300 MHz): d 85.5 (s). 19F NMR (CD2Cl2,
300 MHz): d ꢀ79.1 (s).
˚
radiation (k = 0.71073 A). A hemisphere of data was
collected using a counting time of 10 seconds per frame
at 25 °C. Details of crystal data, data collection and
structure refinement are listed in Table 3. Data reduc-
tions were performed using the SAINT [25] software and
the data were corrected for absorption using SADABS
[26]. The structures were solved by direct methods using
SIR 97 [27] and refined by full-matrix least-squares on
F2 with anisotropic displacement parameters for the
non-disordered heavy atoms using SHELXL-97 [28] and
the WINGX [29] software package and thermal ellipsoid

5096
C.G. Andrews, C.L.B. Macdonald / Journal of Organometallic Chemistry 690 (2005) 5090–5097
Table 3
Summary of collection and refinement data for the X-ray diffraction investigations of 4 and 6 Æ 2 toluene
Compound
[InCpIn] [Cp3InCpInCp3], 4
[In Æ toluene]2 [In] [In(OTf)6], 6 Æ 2 toluene
Empirical formula
Formula weight
Temperature (K)
C40H40In4
980.00
298(2)
C20H16F18In4O18S6
1537.97
298(2)
˚
Wavelength (A)
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
C2/c
Crystal system
Space group
Unit cell dimensions
˚
a (A)
15.226(3)
8.5570(14)
21.291(2)
10.4280(13)
˚
b (A)
˚
c (A)
28.316(5)
90
21.014(3)
90
a (°)
b (°)
c (°)
99.089(6)
90
3643.1(11)
102.409(3)
90
2407.6(2)
3
˚
Volume (A )
Z
4
1.787
4
2.242
Dcalc (g cmꢀ3
)
Absorption coefficient (mmꢀ1
F(000)
)
2.526
1904
2.411
2936
h Range for data collection (°)
Limiting indices
1.46–27.49
ꢀ19 < h < 19,ꢀ11 < k < 11,ꢀ36 < l < 36
1.96–23.31
ꢀ22 < h < 23,ꢀ9 < k < 11,ꢀ21 < l < 23
Reflections collected
Independent reflections
Rint
17055
4178
0.0346
10991
3287
0.0324
Data/restraints/parameters
Final R indices [I > 2r(I)]a
4178/3/211
R1 = 0.0280,
wR2 = 0.0606
R1 = 0.0442,
wR2 = 0.0661
1.019
3287/10/263
R1 = 0.0400,
wR2 = 0.0973
R1 = 0.0675,
wR2 = 0.1120
1.027
R indices (all data)
Goodness-of-fit (S)b on F2
Largest differences in peak and hole (e A
ꢀ3
˚
)
0.647 and ꢀ0.446
0.598 and ꢀ0.456
2 2
P
P
P
a
2
2 2
R1(F) = (jFoj ꢀ jFcj)/ jFoj for reflections with Fo > 4(r(Fo)). wR2(F2) = {Rw(jFoj ꢀ jFcj ) / w(jFoj ) }1/2, where w is the weight given each
reflection.
b
P
2
2 2
S = [ w(jFoj ꢀ jFcj ) ]/(n ꢀ p)1/2, where n is the number of reflections and p is the number of parameters used.
plots were produced using SHELXTL [30]. In 4 the hydro-
gen atoms on the ipso-carbon atoms of the terminal Cp
groups and those of the bridging Cp group in the anion
were located in the difference Fourier map and were re-
fined isotropically; all other H atoms in both structures
were placed in calculated positions. The centroid of the
bridging Cp group in the [In(l2,g5-Cp)In] cation is lo-
cated approximately on an inversion center at (0.25,
0.75, 0.5) and the group is thus highly disordered. This
ring was modeled as a rigid ring with C–C distances of
can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Acknowledgments
The funding that has enabled this work has been pro-
vided by the Natural Sciences and Engineering Research
Council (Canada), the Canada Foundation for Innova-
tion, the Ontario Innovation Trust and the Ontario Re-
search and Development Challenge Fund (University of
Windsor Centre for Catalysis and Materials Research).
˚
1.403 A and C–C–C angles of 108.0° with a site occu-
pancy factor of 0.5. The disorder in the orientation of
the toluene molecules in 6 Æ 2 toluene was refined with
models including rigid 6-membered rings with C–C dis-
˚
tances of 1.390 A and C–C–C angles of 120.0°; refine-
ment of the occupancy of each model yielded an
approximate 58:42 ratio.
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