Some new results on the Fischer-Hafner synthesis of vanadium arenes

Article abstract of DOI:10.1016/j.jorganchem.2006.04.027

The biphasic liquid system formed in the Fisher-Hafner reduction of VCl₃ in toluene contains the [V(η⁶-MeC₆H₅)₂]⁺ cation which has been isolated in the solid state as the tetraphenylborato-

Full text of DOI:10.1016/j.jorganchem.2006.04.027

Journal of Organometallic Chemistry 691 (2006) 3458–3463
www.elsevier.com/locate/jorganchem
Some new results on the Fischer–Hafner synthesis of vanadium arenes
a
a,
b
Fabio Marchetti , Guido Pampaloni *, Calogero Pinzino
a
`
Universita di Pisa, Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, I-56126 Pisa, Italy
b
Istituto per i Processi Chimico-Fisici, CNR, Area della Ricerca, Via G. Moruzzi 1, I-56124 Pisa, Italy
Received 14 March 2006; accepted 20 April 2006
Available online 29 April 2006
Abstract
The biphasic liquid system formed in the Fisher–Hafner reduction of VCl3 in toluene contains the [V(g6-MeC6H5)2]+ cation which has
been isolated in the solid state as the tetraphenylborato- (from aqueous solution) or as the [Al2Cl7]ꢀ, [Al4O2Cl10]2ꢀ and [catena-
Al4O2Cl9]ꢀ salt (directly from the biphasic liquid system). The crystal structures of [V(g6-MeC6H5)2]2[Al4O2Cl10] (2), and [V(g6-
MeC6H5)2][catena-Al4O2Cl9] (3), have been solved representing the first structural report of the [V(g6-MeC6H5)2]+ cation (compounds
2 and 3) and of the polymeric nonachlorodioxoaluminate anion [Al4O2Cl9]ꢀ (compound 3).
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Structure; Vanadium; Toluene; Arene; Aluminates; Fischer–Hafner
1. Introduction
{[Cr(g6-C6H6)2]AlX4}3 Æ 4AlX3, X = Cl, Br. Recently, the
[Cr(g6-C6H6)2][Al3OCl8] derivative has been isolated from
the biphasic liquid system using commercially available
and not purified starting materials and structurally charac-
terized [5].
Working on the VCl3/Al/AlCl3/1,3,5-Me3C6H3 system,
Calderazzo et al. proposed that the primary product of
the Fischer–Hafner reduction of VCl3 was [V(g6-1,3,5-
Me3C6H3)2]Al2Cl7 [1n].
The reaction of metal halides with the Al/AlX3 system in
aromatic hydrocarbons has been widely used for the syn-
thesis of g6-arene derivatives of typical d-transition ele-
ments [1] in low oxidation states.
A common feature to the reaction mixtures deriving from
the Fischer–Hafner synthesis of metal-arene compounds is
the formation of a biphasic liquid system consisting of a
dark-coloured lower layer, containing almost all the transi-
tion metal [1a,2]. Atwood [3] has described similar bi-layer-
ing phenomena for tetraalkylammonium derivatives of
large, aluminium-containing anions; the terminology of
‘‘liquid clathrates’’ was introduced for these systems [3].
Attempts have been made to clarify the nature of the
intermediates of the Fischer–Hafner synthesis, mainly
concerning vanadium and chromium systems. As far as
chromium is concerned, Fischer and Seeholzer [4]
showed that the primary product of the reaction between
CrCl3/Al/AlCl3 in benzene had the composition
Cr3Al7X24(C6H6)6 corresponding to the formulation
We have recently prepared large amounts of V(g6-
CH3C6H5)2 from commercially available, not further puri-
fied, VCl3 and AlCl3, and in some occasions we observed
that solid products formed from the lower, deep brown
liquid phase during the cooling of the reaction mixture.
In this paper, we report on the solid products obtained
thereof as a contribution to the identification of the pri-
mary products formed in the Fischer–Hafner reduction.
2. Results and discussion
It is known in the literature that V(g6-1,3,5-Me3C6H3)2
is obtained in quantitative yields by addition of THF to the
biphasic liquid system which forms by reduction of VCl3
with AlCl3 in 1,3,5-Me3C6H3 in the presence of excess alu-
*
Corresponding author. Tel.: +39 050 2219 219; fax: +39 050 2219 246.
E-mail address: pampa@dcci.unipi.it (G. Pampaloni).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.04.027

F. Marchetti et al. / Journal of Organometallic Chemistry 691 (2006) 3458–3463
3459
minium [1n]. If the excess aluminium is removed by filtra-
tion before the addition of THF, the vanadium(I) species
[V(g6-1,3,5-Me3C6H3)2]AlCl4 is obtained [1n].
O2Cl10] (2). The IR spectrum shows the absorptions typical
of the aromatic ring and of the Al–(O)–Cl fragment in the
1000–400 cmꢀ1 range [8]. The presence of the decachlorodi-
oxoaluminato dianion is probably due to some water acci-
dentally introduced in the reaction mixture or to some
impurities present in the starting materials.
The crystal structure of compound 2 is shown in Fig. 1
and a selection of bond distances and angles is reported in
Table 1. The solid consists of centrosymmetric [V(g6-
MeC6H5)2]+ cations, reported here for the first time, and
[Al4O2Cl10]2ꢀ anions, organized in alternating layers in
the b direction. There are two non equivalent cations for
each anion showing similar geometries. As imposed by
the inversion centre, the toluene rings are parallel with
eclipsed ring carbon atoms and with the methyl groups
pointing to opposite sides, a conformation which we indi-
In the case of the Fischer–Hafner system VCl3/Al/
AlCl3/toluene, the [V(g6-MeC6H5)2]+ cation cannot be
isolated in THF due to the disproportionation to the dinu-
clear, chloride bridging, vanadium(II) derivative [V2(l-
Cl)3(THF)6]AlCl4 and V(g6-MeC6H5)2 [6], see Scheme 1.
In an attempt to isolate some species directly from the
‘‘liquid clathrate’’, we did several, large-scale Fischer–Haf-
ner reductive complexation reactions of VCl3 in toluene
starting from used-as-received reagents. After filtration of
excess aluminium, the liquid phase was treated with non
polar solvents (chlorinated or aliphatic hydrocarbons) or,
alternatively, heated in vacuo at ca. 70 ꢁC, but we never
succeeded in the isolation of a solid compound.
We have been able to obtain a solid substance only when
the deeply coloured layer was added to a concentrated
water solution of NaBPh4; as soon as the addition was
complete (10 min) the dark coloured solid which formed
was isolated by filtration. The treatment of the solid
with heptane, allowed the separation of an insoluble
orange compound, identified as the paramagnetic
[leff(292 K) = 2.80 BM] [V(g6-MeC6H5)2]BPh4 (1), from a
soluble dark brown derivative which was characterized as
V(g6-MeC6H5)2, see Scheme 2.
The formation of the vanadium(0) derivative is probably
due to the disproportionation of the vanadium(I) cation as
observed in THF [6]. We did not make any attempt to
characterize the species present in the aqueous solution in
order to confirm this hypothesis. Although 1 is obtained
in poor yields (6%), its isolation confirms that the [V(g6-
MeC6H5)2]+ cation is stable in the presence of water at
least for a short time [7] and is probably due to the low sol-
ubility of 1 in this medium.
To our surprise, a crystalline compound slowly formed
(some weeks) directly from the ‘‘liquid clathrate’’. This
compound was isolated and identified as the paramagnetic
[leff(292 K) = 2.72 BM] compound [V(g6-MeC6H5)2]2[Al4-
Fig. 1. Projection along a of the crystal structure of [V(g6-MeC6H5)2]2-
0
[Al4O2Cl10] (2). Thermal ellipsoids are at 30% probability. = 1 ꢀ x,
1 ꢀ y, ꢀz.
Table 1
6
˚
Selected bond lengths (A) and angles (ꢁ) in [V(g -MeC6H5)2]2[Al4O2Cl10
(2)
]
V(1)–C(1)
V(1)–C(2)
V(1)–C(3)
V(1)–C(4)
V(1)–C(5)
V(1)–C(6)
V(1)–Tol1a
Al(1)–Cl(1)
Al(1)–Cl(2)
Al(1)–Cl(3)
Al(1)–O
2.282(6)
2.228(6)
2.217(6)
2.245(6)
2.220(6)
2.232(6)
1.747
2.129(2)
2.108(2)
2.128(2)
1.768(4)
V(2)–C(8)
V(2)–C(9)
V(2)–C(10)
V(2)–C(11)
V(2)–C(12)
V(2)–C(13)
V(2)–Tol2a
Al(2)–Cl(4)
Al(2)–Cl(5)
Al(2)–O
2.283(6)
[V2(m-Cl)3(THF)6][AlCl4]
2.232(6)
2.203(6)
2.240(7)
2.223(7)
2.210(7)
1.745
2.106(2)
2.102(2)
1.801(4)
1.798(4)
+
arene =
MeC6H5
V(η6-MeC6H5)2
1) Al/ AlCl /arene
3
2) filtration Al
3) THF
VCl3
arene =
1,3,5-Me C H
6 3
[V(η6-1,3,5-Me3C6H3)2][AlCl4]
3
Scheme 1.
Al(2)–O0
1) Al/AlCl3/toluene, reflux, 12 h
2) filtration Al
O–Al(1)–Cl(1)
O–Al(1)–Cl(2)
O–Al(1)–Cl(3)
Al(1)–O–Al(2)
Al(1)–O–Al(20)
Al(2)–O–Al(20)
106.2(2)
O–Al(2)–O0
86.5(2)
112.1(2)
115.7(2)
114.9(1)
112.3(2)
112.9(1)
VCl3
"liquid clathrate"
111.0(2)
106.7(1)
131.8(2)
133.8(2)
93.5(2)
O–Al(2)–Cl(4)
O–Al(2)–Cl(5)
O0–Al(2)–Cl(4)
O0–Al(2)–Cl(5)
Cl(4)–Al(2)–Cl(5)
[V(η6-MeC6H5)2][BPh4]
NaBPh4
H2O
+
V(η6-MeC6H5)2
Numbers in parenthesis refer to the least significant digits.
a
Scheme 2.
Tol1 and Tol2 are the centroids of the toluene ligand.

3460
F. Marchetti et al. / Journal of Organometallic Chemistry 691 (2006) 3458–3463
cate as trans-eclipsed. Noteworthy is the fact that such a
conformation is frequently observed in the bis(g6-toluene)
derivatives of Cr(I) [9], while the known structures of
methyl-substituted bis(g6-arene) derivatives of vanadium
show an eclipsed arrangement of either methyl and
ring carbon atoms, the examples being [V(g6-1,3,5-
Me3C6H3)2]+/0/ꢀ species [1n,10].
The crystal structure of compound 3 is shown in Fig. 2
and a selection of bond distances and angles is reported in
Table 2. The structure consists of [V(g6-MeC6H5)2]+ cat-
ions and of a polymeric nonachlorodioxoaluminate anion.
The vanadium(I) bis(g6-toluene) cations are in special posi-
tions with the vanadium lying on a twofold axis almost
parallel to the toluene plane. Due to the presence of the
twofold axis, the two arene rings have a nearly cis-eclipsed
conformation (the methylꢁ ꢁ ꢁTol1ꢁ ꢁ ꢁTol10ꢁ ꢁ ꢁmethyl0 torsion
angle is 7.8ꢁ) and the toluene planes are almost parallel
(1.3ꢁ). Such a conformation is similar to that observed
for M(g6-MeC6H5)2, M = Ti [12], Nb [13], and in some
recently reported species of chromium(I) containing steri-
cally demanding anions [14].
The tetranuclear, centrosymmetric [Al4O2Cl10]2ꢀ anion
shows the typical [11] structure made of two types of alu-
minium-containing tetrahedral units, {AlCl2O2} and
{AlCl3O}, arranged in such a way that the two oxygen
atoms belong to a common edge in the {AlCl2O2} unit
described by Al(2), and are terminal in the {AlCl3O} unit
described by Al(1). The Al2O2 four-membered ring experi-
ences the repulsions between the atoms placed in diagonal
positions; the greater charge density on aluminium with
respect to that on the oxygen ones causes stronger
Al(2)ꢁ ꢁ ꢁAl(20) repulsions thus reducing the O–Al(2)–O0
angle [86.5(2)ꢁ] with respect to the Al(2)–O–Al(20) one
[93.5(2)ꢁ].
On standing, the ‘‘liquid clathrate’’ gave another crop of
solid consisting of two vanadium(I) derivatives: [V(g6-
MeC6H5)2][Al4O2Cl9] (3) and [V(g6-MeC6H5)2][Al2Cl7]
(4), whose separation was possible under a microscope
due to the crystalline nature of 3.
The IR spectrum of 3 shows the absorptions typical of
the aromatic ring and of the Al–(O)–Cl fragment in the
1000–400 cmꢀ1 range [8]. Compound 4 has a simpler IR
spectrum in the low wavenumber region due to the absence
of Al–O bonds.
Table 2
6
˚
Selected bond lengths (A) and angles (ꢁ) in [V(g -MeC6H5)2][catena-
Al4O2Cl9] (3)
V–C(1)
V–C(2)
V–C(3)
V–C(4)
V–C(5)
V–C(6)
V–Tola
2.265(14)
2.234(14)
2.216(15)
2.246(15)
2.210(14)
2.215(14)
1.742
Al(1)–Cl(1)
Al(1)–Cl(2)
Al(1)–Cl(3)
Al(1)–O
2.071(5)
2.095(5)
2.261(4)
1.729(8)
2.089(5)
2.092(5)
1.810(8)
1.816(8)
Al(2)–Cl(4)
Al(2)–Cl(5)
Al(2)–O
Al(2)–O0
O–Al(1)–Cl(1)
O–Al(1)–Cl(2)
O–Al(1)–Cl(3)
Al(1)–Cl(3)–Al(100)
Al(1)–O–Al(2)
Al(1)–O–Al(20)
Al(2)–O–Al(20)
112.9(3)
109.5(3)
99.0(3)
117.3(3)
131.3(5)
134.0(5)
93.7(4)
O–Al(2)–O0
86.3(4)
111.4(3)
114.5(3)
115.6(3)
111.4(3)
114.7(2)
O–Al(2)–Cl(4)
O–Al(2)–Cl(5)
O0–Al(2)–Cl(4)
O0–Al(2)–Cl(5)
Cl(4)–Al(2)–Cl(5)
The isolation of [V(g6-MeC6H5)2][Al2Cl7] represents a
further evidence of the presence of heptachlorodialuminate
anions in the lower liquid phase from the Fischer–Hafner
reduction of VCl3, as previously suggested by some of us
in the case of the VCl3/Al/AlCl3/1,3,5-Me3C6H3 system
[1n].
Numbers in parenthesis refer to the least significant digits.
a
Tol is the centroid of the toluene ligand.
ꢀ
Fig. 2. View of the crystal structure of [V(g6-MeC6H5)2][catena-Al4O2Cl9]
(3). Thermal ellipsoids are at 30% probability.
Fig. 3. View of the structure of the polyanion [catena-Al4O2Cl9] . = ꢀx,
0
00
ꢀy, ꢀz, = ꢀx, y, 1/2 ꢀ z.

F. Marchetti et al. / Journal of Organometallic Chemistry 691 (2006) 3458–3463
3461
DFT calculations performed on chromium(I)- [14b] and
4. Experimental
on vanadium(I) bis(g6-toluene) cations have shown that
the energy gap between the cis- and the trans-eclipsed con-
formations in the gas phase is small (0.09 and 1.77 kcal/mol
for chromium and vanadium, respectively), thus suggesting
that the conformation of the toluene rings in the crystal is
mainly dictated by the packing forces.
As far as the anionic part of compound 3 is con-
cerned, the Cl(3) and Cl(30) atoms are placed on twofold
axes and bridge two centrosymmetric [Al4Cl8Cl2/2O2]ꢀ
units. As a result, a polymeric anion growing in the c
direction in a zigzag fashion is obtained, see Fig. 3. As
reported in Table 2, the bond distances of the bridging
chlorides are longer than the terminal ones by ca. 10%.
The presence of bridges makes the O–Al(1)–Cl(3) bond
angle [99.0(3)ꢁ] smaller than the O–Al(1)–Cl(1) and O–
Al(1)–Cl(2) ones [112.9(3) and 109.5(3)ꢁ, respectively].
The remaining part of the [Al4Cl8Cl2/2O2]ꢀ units is sub-
stantially similar to that observed in the [Al4O2Cl10]2ꢀ
mononuclear anions.
4.1. General procedures
Unless otherwise stated, all the operations were car-
ried out under an atmosphere of prepurified nitrogen.
IR spectra were measured with the FT1725X instru-
ment on or nujol and/or polychlorotrifluoroethylene
(PCTFE) mulls. Magnetic susceptibility measurements
were performed with
a
Faraday balance using
CuSO4 Æ 5H2O as standard. Pascal contributions were
used to calculate the diamagnetic correction [15].
DFT geometry optimization and calculation of the elec-
tron spin density distribution were performed using the
Linux version of the SPARTAN ’02 software [16]. We
adopted the BP86 scheme, that uses the functional pro-
posed by Becke [17] and Perdew [18], and the 6-31G**
basis set that is appropriate for calculations of split-
valence-plus-polarization quality.
VCl3 (Pechiney), AlCl3 (Carlo Erba) and finely ground
aluminium (C. Erba) were used as received.
3. Conclusions
4.2. Preparation of [V(g6-MeC6H5)2]BPh4 (1)
By addition of the deeply coloured, liquid phase formed
in the Al/AlCl3 reduction of VCl3 in toluene to a concen-
trated aqueous solution of NaBPh4, the vanadium(I)
bis(g6-toluene) cation has been isolated as the tetra-
phenylborato salt. Although the main reaction is the
disproportionation V(I) ! V(0) + V(II), the isolation of
[V(g6-MeC6H5)2][BPh4] has definitely proved that the
[V(g6-MeC6H5)2]+ cation is the primary product of the
cited Fischer–Hafner reduction and that, probably due to
its low solubility in water, it can survive in such a medium
for short periods of time.
A
suspension of VCl3 (12.75 g, 81 mmol), finely
ground aluminium (3.12 g, 115 mmol), AlCl3 (12.94 g,
97 mmol) in toluene (100 ml) was heated overnight at
the reflux temperature. A red suspension was obtained
which was filtered at room temperature. The liquid phase
consisted of two layers: a pale yellow upper layer, con-
taining only traces of vanadium and chloride, and a deep
red lower one containing most of the vanadium intro-
duced (0.059 g/ml of vanadium corresponding to the
93% of vanadium introduced).
The identification of [V(g6-MeC6H5)2][Al2Cl7] (4), as
obtained from the ‘‘liquid clathrate’’, represents a further
evidence of its involvement in the Fischer–Hafner reduc-
tion of VCl3, as previously suggested by some of us in
the case of the VCl3/Al/AlCl3/1,3,5-Me3C6H3 system.
The isolation of compounds 2 and 3, two vanadium(I)
bis(g6-toluene) cations containing deca- or nonachlorodi-
oxoaluminato anions is noteworthy from a more general
point of view. In fact, they represent the first crystallo-
graphic report on the [V(g6-MeC6H5)2]+ cation and on
the polymeric nonachlorodioxoaluminato anion [catena-
Al4O2Cl9]ꢀ. Moreover, it has to be noticed that the confor-
mation of the toluene rings is different in the two com-
pounds, i.e., the methylꢁ ꢁ ꢁTol1ꢁ ꢁ ꢁTol10ꢁ ꢁ ꢁmethyl0 torsion
angle is 180ꢁ in 2 and 7.8ꢁ in compound 3. The situation
is reminiscent of that observed in the structural chemistry
of chromium(I) bis(g6-toluene) cations [14]: since the
DFT calculated energy gap between the cis- and the
trans-eclipsed conformations is small, the conformation
of the toluene rings in the crystal is dictated by the packing
forces and it can be changed on changing the steric demand
of the anion.
A sample of the deeply coloured solution (18 ml,
20.8 mmol of vanadium) was added to a solution of
NaBPh4 (10.61 g, 31 mmol) in water (40 ml) at room tem-
perature. An immediate, exothermic reaction took place
with formation of a solid; the solution turned pale violet.
The solid was quickly collected by filtration, washed with
water and dried in vacuo at room temperature in the pres-
ence of P4O10. The solid (1.144 g), which appeared as a
mixture of a orange and a dark brown compounds, was
treated with heptane (50 ml) and stirred at room tempera-
ture for 2 h. The suspension was filtered and a orange solid
was separated from a brown solution. The solid was
washed with heptane (2 · 5 ml) and dried in vacuo at room
temperature
affording
[V(g6-MeC6H5)2][BPh4]
(1),
(0.690 g, 6%) as an orange microcrystalline solid. Anal.
Calc. for C38H36BV: C, 82.3; H, 6.5; V, 9.2. Found: C,
ꢀ1
~
82.8; H, 6.3; V, 8.9%. IR (Nujol): m=cm 3048m-s, 3035
m-s, 1608w, 1580m, 1151 m-s, 1031s, 742s, 731vs, 709vs,
702s, 603s, 481w. vcMorr ¼ 3:34 ꢂ 10ꢀ3 cgsu, diamagn. corr.
ꢀ361.7 · 10ꢀ6 cgsu, leff (292 K) = 2.80 BM. The filtrate
was evaporated to dryness affording V(g6-MeC6H5)2
(0.372 g, 8%).

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F. Marchetti et al. / Journal of Organometallic Chemistry 691 (2006) 3458–3463
4.3. Isolation of [V(g6-MeC6H5)2]+ cations from the
‘‘liquid clathrate’’
atmosphere. The intensity data collection was carried out
with the x/2h scan mode, collecting a redundant set of
data. Three standard reflections were measured every 97
measurements to check sample decay. The intensities were
corrected for Lorentz and polarization effects and for
absorption by the w-scan method [19]. The structure solu-
tions were obtained by direct methods [20], and the struc-
tural model was refined with full-matrix least-squares on
F2 [20]. Some utilities contained in the WINGX suite [21] were
used. A selection of crystal parameters is listed in Table 3.
The asymmetric unit of compound 2 consists of one half
of the [Al4Cl10O2]2ꢀ anion placed near an inversion centre
and two half of the [V(g6-MeC6H5)2]+ cation, the vana-
dium atoms being placed on two inversion centres. The
hydrogen atoms were in calculated positions and let to
‘‘ride’’ on the corresponding carbon atoms during the
refinement. In the last refinement cycles the heavy atoms
were refined with anisotropic thermal parameters and the
reliability factors listed in Table 3 were obtained.
A suspension of VCl3 (13.72 g, 87 mmol), finely ground
aluminium (3.35 g, 124 mmol), AlCl3 (13.94 g, 104 mmol)
in toluene (100 ml) was heated overnight at the reflux tem-
perature. A red suspension was obtained which was filtered
at room temperature. The liquid phase consisted of two
layers: a pale yellow upper layer, containing only traces
of vanadium and chloride, and a deep red lower one con-
taining 94% of the vanadium introduced. After some weeks
in the dark at room temperature, deep red crystals were
present. They were collected by filtration, washed with a
small amount of toluene and shortly dried in vacuo at
room temperature affording 3.125 g (7.5%) of [V(g6-
MeC6H5)2]2[Al4O2Cl10] (2), as deep red crystals sensitive
to oxygen and moisture. Anal. Calc. for C28H32Al4-
Cl10O2V2: C, 34.8; H, 3.3; Al, 11.2; Cl, 36.7; V,10.6. Found:
C, 35.1; H, 3.6; Al, 11.6; Cl, 36.2; V, 10.1%. IR (Nujol):
ꢀ1
~
m=cm
3059m, 1495w, 1441m, 1383w, 1339w, 1055w,
Due to the instability in the presence of air, crystal of 3
gave broad and irregularly-shaped diffractions, whose
intensity rapidly decrease with increasing h; this prevented
the collection of reflections above h = 22.5ꢁ. The asymmet-
1039m, 993 w, 823m-br, 765m, 680m-br, 496m-s.
vMcorr ¼ 3:14 ꢂ 10ꢀ3 cgsu, diamagn. corr. ꢀ515 · 10ꢀ6 cgsu,
leff (292 K) = 2.72 BM.
After two months, the mother liquor gave another crop
of solid, which was collected by filtration, washed with a
small amount of toluene and dried in vacuo at room temper-
ature affording 1.096 g yellow-brown solid whose elemental
analysis corresponded to the following composition:
{[V(g6-MeC6H5)2][Al2Cl7]}0.85 {[V(g6-MeC6H5)2][Al4O2-
Cl9]}0.15 Æ C7H8. Anal. Calc. for C21H24Al2.3Cl7.3O0.3V: C,
38.6; H, 3.7; Al, 9.5; Cl, 39.6; V,7.8. Found: Cꢀ, 138.0; H,
ric unit consists of an infinite polyanion with the repeating
0.5ꢀ
modulus [Al2Cl4OCl1/2
]
– placed between a inversion
centre and a twofold axis – and by one half of the [V(g6-
MeC6H5)2]+ cation, the vanadium being placed on a two-
fold axis. The hydrogen atoms were in calculated positions
and let to ‘‘ride’’ on the corresponding carbon atoms dur-
ing the final refinement. The final refinement cycle was
done with hydrogen atoms in calculated positions, riding
on the connected carbon atoms; the heavy atoms were
refined with anisotropic thermal parameters. The reliability
factors listed in Table 3.
~
3.4; Al, 10.4; Cl, 39.6; V, 7.6%. IR (Nujol): m=cm 3052m,
1493w, 1441m, 1382w, 1336w, 1055w, 1040m, 995w,
828m, 758m, 685m-w, 495s.
A close examination of the solid revealed the presence of
a yellow brown microcrystalline solid and some deep red
crystals which were carefully separated under the micro-
scope (ca. 0.12 g) from the microcrystalline solid and iden-
tified as [V(g6-MeC6H5)2][Al4O2Cl9] (3). Anal. Calc. for
C14H16Al4Cl9O2V: C, 24.2; H, 2.3; Al, 15.0; Cl, 46.0; V,
7.8. Found: C, 2ꢀ31.9; H, 2.9; Al, 15.0; Cl, 46.6; V, 7.5%.
Table 3
Crystal data and parameters of the structure solution of [V(g6-
MeC6H5)2]2[Al4O2Cl10] (2) and [V(g6-MeC6H5)2][catena-Al4O2Cl9] (3)
Compound
1
2
Empirical formula
Formula weight
Crystal system
Space group
C
964.84
28H32Al4Cl10O2V2
C14H16Al4Cl9O2V
694.18
~
IR (Nujol): m=cm 3059m, 1497w, 1439m, 1380w, 1341w,
Triclinic
Monoclinic
C2/c (no. 15)
13.082(3)
14.900(3)
14.873(3)
–
101.24(2)
–
2843.4(10)
4
1059w, 1042m, 990w, 828m-br, 756m, 685m-br, 493m-s.
The yellow brown microcrystalline solid (ca. 950 mg) was
identified as [V(g6-MeC6H5)2][Al2Cl7]. Anal. Calc. for
C14H16Al2Cl7V: C, 31.3; H, 3.0; Al, 10.0; Cl, 46.2; V, 9.5.
ꢀ
P1 ðno:2Þ
˚
a (A)
9.470(2)
9.759(3)
12.318(3)
102.60(2)
96.84(2)
105.59(2)
1050.8(5)
1
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
Found: C, 30.7; H, 3.5; Al, 10.8; Cl, 45.5; V, 9.0%. IR
ꢀ1
~
(Nujol): m=cm 3059m, 1489w, 1435m, 1382w, 1349w,
3
˚
1062w, 1035m, 491vs.
U (A )
Z
Dcalc (Mg mꢀ3
)
1.525
1.622
4.4. Crystal structure of [V(g6-MeC6H5)2]2[Al4O2Cl10]
(2) and [V(g6-MeC6H5)2][catena-Al4O2Cl9] (3): solution
and refinement
l (mmꢀ1
No. measured
)
1.190
1.330
3300
2490
No. unique [Rint
No. parameters
]
2715 [0.0379]
211
1976 [0.0349]
137
R1, wR2 [I > 2r(I)]
R1, wR2 [all data]
Goodness-of-fit on F2
0.0464, 0.1080
0.0760, 0.1229
1.029
0.0874, 0.2379
0.1246, 0.2728
1.065
Data were collected at 293 K with graphite-monochro-
mated Mo Ka radiation on a Bruker P4 diffractometer
on samples sealed in glass capillaries under a nitrogen

F. Marchetti et al. / Journal of Organometallic Chemistry 691 (2006) 3458–3463
3463
[8] K. Nakamoto, Infrared and Raman Spectra of Coordination Com-
pounds, fifth ed., Wiley, New York, 1997.
Acknowledgements
[9] (a) O.V. Starovskii, Yu.T. Struchkov, Zh. Strukt. Khim. 2 (1961)
162;
The authors thank the Ministero dell’Istruzione,
`
dell’Universita e della Ricerca (MIUR, Roma), Programmi
Chem. Abs. 55 (1961) 26606g;
di Ricerca Scientifica di Notevole Interesse Nazionale, Cof-
inanziamento 2004–2005, and the Consiglio Nazionale
delle Ricerche (C.N.R.) Progetto CNR-MIUR ‘‘Sviluppo
di microcelle a combustibile’’, for financial support.
(b) R.P. Shibaeva, L.O. Atovmyan, L.P. Rozenberg, J. Chem. Soc.,
Chem. Commun. (1969) 649;
(c) R.P. Shibaeva, L.O. Atovmyan, M.N. Orfanova, J. Chem. Soc.,
Chem. Commun. (1969) 1494;
(d) W.E. Broderick, K.W. Choi, W.C. Wan, Proc. Electrochem. Soc.
97 (1997) 1102;
Appendix A. Supplementary material
(e) D. Braga, A.L. Costa, F. Grepioni, L. Scaccianoce, E. Tagliavini,
Organometallics 16 (1997) 2070;
(f) F. Grepioni, G. Cojazzi, S.M. Draper, N. Scully, D. Braga,
Organometallics 17 (1998) 296;
(g) D. Braga, S.M. Draper, E. Champeil, F. Grepioni, J. Organomet.
Chem. 573 (1999) 73;
(h) A. Ho¨nnerscheid, R.E. Dinnebier, M. Jansen, Acta Crystallogr.,
Sect. B 58 (2002) 482.
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre, CCDC 297961
for [V(g6-MeC6H5)2]2[Al4O2Cl10] and CCDC 297962 for
[V(g6-MeC6H5)2][catena-Al4O2Cl9].
Copies
can
be
obtained free of charge from: The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK, fax 44 1223 33
6033; email: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2006.04.027.
[10] (a) G. Fochi, D. Braga, P. Sabatino, Organometallics 7 (1988)
565;
(b) D. Braga, P. Sabatino, Acta Crystallogr., Sect. C 46 (1990) 2308.
[11] (a) U. Thewalt, F. Stollmaier, Angew. Chem., Int. Ed. Engl. 21
(1982) 133;
Angew. Chem. (Suppl.) (1982) 209;
(b) O. Graalmann, M. Hesse, U. Klingebiel, W. Clegg, M. Haase,
G.M. Sheldrick, Angew. Chem., Int. Ed. 22 (1983) 621;
(c) D. Jentsch, P.G. Jones, E. Schwarzmann, G.M. Sheldrick, Acta
Crystallogr., Sect. C 39 (1983) 1173;
References
[1] (a) E.O. Fischer, W. Hafner, Z. Naturforschg. B 10 (1955) 665;
(b) E.O. Fischer, H.O. Stahl, Chem. Ber. 89 (1956) 1805;
(d) T. Probst, O. Steigelmann, J. Riede, H. Schmidbaur, Angew.
Chem., Int. Ed. 29 (1990) 1397;
(c) E.O. Fischer, A. Wirzmuller, Chem. Ber. 90 (1957) 1725;
¨
(e) A. Assoud, G. Meyer, Z. Anorg. Allg. Chem. 627 (2001) 921.
[12] (a) G.G. Tairova, O.N. Krasochka, V.I. Ponomaryov, E.F. Kvashina,
Yu.A. Shvetsov, E.M. Lisetsky, D.P. Kiryukhim, L.O. Atovmyan,
Yu.G. Borod’ko, Trans. Met. Chem. 7 (1982) 189;
(b) O.N. Krasochka, A.F. Shestakov, G.G. Tairova, Yu.A. Shvetsov,
E.F. Kvashina, V.I. Ponomarev, L.O. Atovmyan, Yu.G. Borod’ko,
Khim. Fiz. (1983) 1459;
(d) E.O. Fischer, H.P. Ko¨gler, Chem. Ber. 90 (1957) 250;
(e) E.O. Fischer, F. Scherer, H.O. Stahl, Chem. Ber. 93 (1960) 2065;
(f) E.O. Fischer, H.H. Lindner, J. Organomet. Chem. 1 (1964) 307;
(g) Chr. Palm, E.O. Fischer, F. Baumga¨rtner, Tetrahedron Lett.
(1962) 253;
(h) F. Calderazzo, Inorg. Chem. 3 (1964) 810;
(i) E.O. Fischer, M.W. Schmidt, Chem. Ber. 99 (1966) 2206;
(j) E.O. Fischer, M.W. Schmidt, Chem. Ber. 102 (1969) 1954;
(k) E.O. Fischer, Ch. Elschenbroich, Chem. Ber. 103 (1970) 162;
(l) M.L.H. Green, W.E. Silverthorn, J. Chem. Soc., Dalton Trans.
(1973) 301;
(m) D. O’Hare, A. Rai-Chaudhuri, V. Murphy, J. Chem. Soc.,
Dalton Trans. (1993) 3071;
(n) F. Calderazzo, R. Invernizzi, F. Marchetti, F. Masi, A. Moalli,
G. Pampaloni, L. Rocchi, Gazz. Chim. Ital. 123 (1993) 53;
(o) F. Calderazzo, G. Pampaloni, L. Rocchi, J. Stra¨hle, K. Wurst, J.
Organomet. Chem. 413 (1991) 91.
O.N. Krasochka, A.F. Shestakov, G.G. Tairova, Yu.A. Shvetsov,
E.F. Kvashina, V.I. Ponomarev, L.O. Atovmyan, Yu.G. Borod’ko,
Chem. Abs. 100 (1984) 43387g.
[13] D.L. Clark, J.C. Gordon, J.T. Mc Farlan, R.L. Vincent-Hollis, J.G.
Watkin, B.D. Zwick, Inorg. Chim. Acta 244 (1996) 269.
[14] (a) L. Calucci, U. Englert, E. Grigiotti, F. Laschi, G. Pampaloni, C.
Pinzino, M. Volpe, P. Zanello, J. Organomet. Chem 691 (2006) 829;
(b) F. Benetollo, E. Grigiotti, F. Laschi, G. Pampaloni, M. Volpe, P.
Zanello, J. Sol. State Electrochem. 9 (2005) 732;
(c) R.D. Kohn, D. Smith, M.F. Mahon, M. Prinz, S. Mihan, G.
Kociok-Ko¨hn, J. Organomet. Chem. 683 (2003) 200.
[15] The diamagnetic contributions are from: E. Ko¨nig, Magnetische
Eigenschaften der Koordinations– und Metallorganischen Verbind-
[2] (a) E.O. Fischer, H.P. Fritz, Angew. Chem. 73 (1961) 353;
(b) W.E. Silverthorn, Adv. Organomet. Chem. 13 (1975) 48.
[3] J.L. Atwood, Liquid clathrates, in: J.L. Atwood, J.E.D. Davies,
D.D. MacNicol (Eds.), Inclusion Compounds, vol. 1, Academic
Press, New York, 1984, p. 375 (Chapter 9), and references therein.
[4] E.O. Fischer, J. Seeholzer, Z. Anorg. Allg. Chem. 312 (1961) 244.
[5] A. Fischer, J. Organomet. Chem. 525 (1996) 291.
¨
ungen der Ubergangselemente in Landolt-Bo¨rnstein, sixth ed.Zah-
lenwerte und Funktionen aus Naturwissenschaften und Technik, vol.
2, Springer-Verlag, Berlin, Go¨ttingen, Heidelberg, 1966.
[16] SPARTAN ’02, Wavefunction, Inc. 18401 Von Karman Avenue, Suite
370 Irvine, CA 92612, USA.
[6] F. Calderazzo, G.E. De Benedetto, G. Pampaloni, C. Maichle-
Mo¨ssmer, J. Stra¨hle, K. Wurst, J. Organomet. Chem. 451 (1993) 73.
[7] The [V(g6-1,3,5-Me3C6H3)2][BPh4] derivative was obtained in quan-
titative yields by reaction of [V(g6-1,3,5-Me3C6H3)2]I with NaBPh4 in
water. Both this compound and 1 are stable in the presence of water
at least for 15 min but decompose immediately in the presence of air
or in the presence of moist acetone or methanol.
[17] A.D. Becke, Phys. Rev. A 38 (1988) 3098.
[18] J.P. Perdew, Phys. Rev. B 33 (1986) 8822.
[19] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr., Sect.
A 24 (1968) 351.
[20] G.M. Sheldrick, SHELXTL-Plus, Rel. 5.1, Bruker-AXS Inc., Madison,
WI, USA, 1997.
[21] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.