Group 4 metallocene complexes with pendant nitrile groups

Article abstract of DOI:10.1016/j.jorganchem.2011.02.032

The preparation of a new functionalized cyclopentadienyl ligand bearing a nitrile pendant substituent, (C₅H₄CMe₂CH ₂CN)^- is reported. The corresponding lithium salt of this ligand (1) was prepared by the reaction of in situ lithiated acetonitrile with 6,6-dimethylfulvene. The ligand was subsequently utilized for the synthesis of group 4 metal complexes [(η⁵-C₅H₄CMe ₂CH₂CN)₂MCl₂] (M = Ti, 2; M = Zr, 3; M = Hf, 4), [(η⁵-C₅H₅) (η⁵-C₅H₄CMe₂CH ₂CN)MCl₂] (M = Ti, 7; M = Zr, 8), and [(η⁵- C₅Me₅) (η⁵ C₅H ₄CMe₂CH₂CN)₂ZrCl₂] (9). Alternative route to 2 comprised the preparation of half-sandwich complex [(η⁵-C₅H₄CMe₂CH ₂CN)TiCl₃] (6). The prepared compounds were characterized by common spectroscopic methods and the solid state structures of complexes 2, 3, 4, 7, and 9 were determined by the single-crystal X-ray diffraction analysis. In addition, compound 7 was converted to the corresponding dimethyl derivative [(η⁵-C₅H₅) (η⁵-C ₅H₄CMe₂CH₂CN)TiMe₂] (10) and also treated with the chloride anion abstractor Li[B(C₆F ₅)₄] to generate the cationic complex with the coordinated nitrile group, as suggested by the NMR spectroscopy. A formation of yet another cationic complex was observed upon treating compound 10 with (Ph ₃C)[B(C₆F₅)₄].

Full text of DOI:10.1016/j.jorganchem.2011.02.032

Journal of Organometallic Chemistry 696 (2011) 2364e2372
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Group 4 metallocene complexes with pendant nitrile groups
a
b
,
1
a
a
,
ꢀ a
*
ꢀ
ꢀ
ꢀ
ꢀ
Jirí Pinkas , Róbert Gyepes , Jirí Kubista , Michal Horácek , Martin Lamac
a
ꢀ
J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague 8, Czech Republic
b Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history:
The preparation of a new functionalized cyclopentadienyl ligand bearing a nitrile pendant substituent,
(C5H4CMe2CH2CN)ꢀ is reported. The corresponding lithium salt of this ligand (1) was prepared by the
reaction of in situ lithiated acetonitrile with 6,6-dimethylfulvene. The ligand was subsequently utilized
for the synthesis of group 4 metal complexes [(h5eC5H4CMe2CH2CN)2MCl2] (M ¼ Ti, 2; M ¼ Zr, 3;
Received 12 January 2011
Received in revised form
17 February 2011
Accepted 28 February 2011
M
¼
Hf, 4), [(h5eC5H5)
(
h5eC5H4CMe2CH2CN)MCl2] (M
¼
Ti, 7;
M
¼
Zr, 8), and [(h
5-C5Me5)
(
h5 C5H4CMe2CH2CN)2ZrCl2] (9). Alternative route to 2 comprised the preparation of half-sandwich
Keywords:
Metallocene
Group 4 elements
Cyclopentadienyl ligands
Nitrile
complex [(h5eC5H4CMe2CH2CN)TiCl3] (6). The prepared compounds were characterized by common
spectroscopic methods and the solid state structures of complexes 2, 3, 4, 7, and 9 were determined by
the single-crystal X-ray diffraction analysis. In addition, compound 7 was converted to the corresponding
dimethyl derivative [(h5eC5H5) (h5eC5H4CMe2CH2CN)TiMe2] (10) and also treated with the chloride
anion abstractor Li[B(C6F5)4] to generate the cationic complex with the coordinated nitrile group, as
suggested by the NMR spectroscopy. A formation of yet another cationic complex was observed upon
treating compound 10 with (Ph3C)[B(C6F5)4].
Structure elucidation
Ó 2011 Published by Elsevier B.V.
1. Introduction
undoubtedly directed toward broadening the range of synthetic
approaches providing a convenient access to variously substituted
Cyclopentadienyl ligands occupy a prominent position in the
coordination chemistry of group elements. Metallocene
compounds.
In contrast to the variety of pendant substituents utilized in
4
complexes of these metals were found to act as effective catalysts
for various processes, polymerization of olefins being among the
most important examples, and found applications also as reagents
in organic synthesis [1]. Such findings have been continuously
prompting vigorous research activity in this area during past
decades. However, new derivatives of the discussed complexes,
especially those bearing additional functional groups, are still
group 4 metallocene complexes, examples of compounds having
a ChN functionality in the sidearm are obviously missing [5,6]. The
nitrile group represents an unsaturated, yet relatively robust
N-donor group, which has a potential for further synthetic modi-
fication. We therefore decided to prepare such derivatives. In this
contribution, we report the synthesis of a new functionalized
cyclopentadienyl ligand possessing the nitrile group by a straight-
forward and high-yielding method and its utilization for the
preparation of group 4 metal complexes.
demanded. Pendant moieties attached to the h
5-cyclopentadienyl
ligand could alter chemical and/or catalytic properties of such
complexes [2]. Furthermore, reactive groups could be further
modified or used to attach other molecular building blocks [3].
Nevertheless, the range of synthetic methods to modify group 4
metallocenes is significantly limited, mainly due to their incom-
patibility with nucleophilic reagents common in organic synthesis.
The functional groups are therefore often introduced to the ligand
before the transmetalation step [4]. Future efforts must be
2. Results and discussion
2.1. Synthesis of the new ligand and its complexes
The introduction of nitrile group to the cyclopentadienyl moiety
was carried out by the nucleophilic addition of in situ formed
LiCH2CN to 6,6-dimethylfulvene (Scheme 1). Such approach starting
with fulvenes is well precedented, even involving functionalization
with polar moieties [7]. The organyllithium reagent was conve-
niently obtained by lithiation of acetonitrile by 1 M equivalent of
n-butyllithium in THF at low temperature [8]. The reaction with
fulvene afforded the lithium salt of the substituted cyclopentadienyl
* Corresponding author. Tel.: þ420 266 053 735; fax: þ420 286 582 307.
ꢀ
E-mail address: martin.lamac@jh-inst.cas.cz (M. Lamac).
Present address: J. Selye University in Komárno, Bratislavská cesta 3322, 945 01
1
Komárno, Slovakia.
0022-328X/$ e see front matter Ó 2011 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2011.02.032

J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
2365
Scheme 1. Preparation of lithium salt 1 and complexes 2e4.
Scheme 2. Preparation of complex 6; alternative route to 2.
(1) in almost quantitative yield. NMR spectroscopy of 1 revealed the
expected set of signals for the CMe2 and CH2 groups, and signals for
two mutually interacting pairs of protons of the monosubstituted
cyclopentadienyl moiety in 1H and the corresponding resonances in
13C spectra. Additionally, the nitrile carbon resonance was found at
dC 120.2 ppm, which lies in a usual range for this group.
All newly prepared compounds were characterized by conven-
tional spectral methods. The NMR spectra showed an expected
pattern for all metal complexes. In comparison to lithium salt 1,
complexes of the ligand exhibited a downfield shift of the reso-
nances for the cyclopentadienyl moiety. In 13C spectra, the nitrile
carbon signal was observed with dC in the range 118.3e119.0 ppm
for all compounds 2e4, 6, and 7e9, indicating that the pendant
functionality remained uncoordinated in solution. It became
evident from IR spectra that the nitrile group is not significantly
influenced also in the solid state. For all above mentioned
complexes the band corresponding to the ChN stretching vibration
appeared in the region typical for the free nitrile group
(2237e2250 cmꢀ1). Electron impact (EI) mass spectra confirmed
the formulation of compounds 2e4, 6, and 7e9 displaying molec-
ular ions ([Mþꢂ]) and ions resulting from simple fragmentation
(e.g., [MeCl]þ, [Me(C5H4CMe2CH2CN)]þ, [Me(C5H5)/(C5Me5)]þ,
[C5H4CMe2CH2CN]þ). In addition, combustion elemental analyses
were performed for all complexes.
Lithium salt 1 was subsequently transmetalated with 0.5 M
equivalents of group 4 metal tetrachlorides [9]. In the case of tita-
nium, the preformed adduct TiCl4$2THF was used in order to
decrease Lewis acidity of the metal center. The reactions were
performed in THF at ꢀ78 ꢁC and afforded the corresponding bent
metallocene complexes [(h5eC5H4CMe2CH2CN)2MCl2] (M ¼ Ti, 2;
M ¼ Zr, 3; M ¼ Hf, 4) in low (Ti) to moderate (Zr, Hf) yields as
crystalline solids (Scheme 1). With the aim to increase the yield of
compound 2, another route was tested utilizing TiCl3$3THF and
a subsequent oxidative work-up with aqueous HCl [9b]. Unfortu-
nately, this approach failed to produce 2 in sufficient yields, while
significant decomposition was observed. Another route via the pre-
paration of half-sandwich complex 6 succeeded better (Scheme 2). In
the first step, 1 was converted to the silylated derivative 5 (>90% of
the depicted isomer as observed by NMR), which was then reacted
with TiCl4 in toluene to produce the trichloride [(h5eC5H4CMe2CH2
CN)TiCl3] (6). This complex could be further converted to 2 by the
reaction with 1 M equivalent of 1. The overall yield of 2 using this
route was 59%.
2.2. Crystal structure analyses
In addition to the spectral characterization, molecular structures
of compounds 2, 3, 4, 7, and 9 were determined by the single-crystal
X-ray diffraction analysis. The structures of compounds 2e4 are
isomorphous (a view of the structure is shown for 2 in Fig. 1; for 3
and 4, see the Supplementary material). These complexes crystal-
lized in the chiral orthorhombic space group P212121 with one C2-
symmetric molecule in the asymmetric unit. Selected geometric
data are given in Table 1. The compounds exhibit the expected bent
metallocene structure with the pendant substituents both oriented
Inanotherseries of reactions, mixedmetallocene dichlorides were
synthesized from equimolar amounts of monocyclopentadienyl
precursors and lithium salt 1 under similar conditions as for previous
syntheses (Scheme 3). Thus, complexes [(h5eC5H5)
(
h5eC5H4
CMe2CH2CN)MCl2] (M ¼ Ti, 7; M ¼ Zr, 8) were prepared starting from
[(h5eC5H5)MCl3] in good yields. Since for the zirconium compound 8
it was not possible to obtain good quality crystals for X-ray analysis,
we also prepared an analog with the permethylated cyclopentadienyl
ligand [(h5eC5Me5) (h5eC5H4CMe2CH2CN)2ZrCl2] (9) starting from
[(h5eC5Me5)ZrCl3]. In the case of hafnium, we attempted the
synthesis of analogous complex [(h5eC5H5) (h5eC5H4CMe2CH2CN)
HfCl2], but we encountered problems with low reaction rate. When
the mixture was heated to accomplish the reaction, a mixture of
products was obtained containing the desired product, but also
symmetrically substituted complexes [(h5eC5H5)2HfCl2] and 4.
Isolation of the mixed hafnocene dichloride from the mixture was
unsuccessful.
Scheme 3. Preparation of complexes 7e9.

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J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
Fig. 2. A view of the molecular structure of 7 showing the atom labeling scheme and
displacement ellipsoids at the 30% probability level.
Molecular structures of mixed metallocene dichlorides 7 and 9
are depicted in Figs. 2 and 3, respectively. Selected geometric data
are summarized in Table 2. Complex 7 crystallized in the chiral
monoclinic space group P21 with one molecule in the asymmetric
unit, while complex 9 crystallized as a racemate in the centro-
symmetric monoclinic space group P21/n with two molecules in the
asymmetric unit, which differ slightly in the conformation of
pendant group and in the mutual rotation of the substituted
cyclopentadienyl rings. Both structures 7 and 9 are similar to the
previously discussed complexes concerning the conformation of
the nitrile substituted cyclopentadienyl ligand, while the other
cyclopentadienyl is obviously replaced by the unsubstituted or
permethylated one.
Fig. 1. A view of the molecular structure of 2 showing the atom labeling scheme and
displacement ellipsoids at the 30% probability level. Complexes 3 and 4 are iso-
structural; for their graphical representations, see the Supplementary material.
toward the opened side of the metallocene wedge, which is man-
ifested by the dihedral angle C1eCg(1)eCg(2)eC11 (denoted as q)
found for complexes 2e4 in the range 28.0e29.5ꢁ (absolute value).
This is in contrast with similar structures of substituted bent
metallocenes with more sterically demanding substituents [9a,10].
Nitrile groups at the end of each arm are pointing away from the
metallocene core precluding any coordination to the metal center.
Likewise, no intermolecular interactions were found in the dis-
cussed structures.
Table 1
Selected distances and angles [in Å and ꢁ] for 2, 3, and 4.a
Compound
2 (M ¼ Ti)
3 (M ¼ Zr)
4 (M ¼ Hf)
MeCg1
2.0991(12)
2.2116(13)
2.191(3)
MeCg2
2.0819(11)
2.2287(14)
2.206(4)
MeC (1e15; range)
MeCl1
2.323(2)ꢀ2.519(2)
2.446(3)e2.610(3)
2.4337(8)
2.422(6)e2.600(7)
2.409(2)
2.3457(7)
MeCl2
2.3585(8)
2.4446(7)
2.419(2)
C1/11eC6/16
C6/16eC9/19
C9/19eC10/20
C10/20eN1/2
:Cp(1),Cp(2)
Cl1eMeCl2
1.519(3)/1.525(3)
1.543(3)/1.551(4)
1.467(4)/1.466(4)
1.140(3)/1.144(3)
58.1(2)
1.527(4)/1.529(4)
1.543(4)/1.540(4)
1.462(4)/1.468(4)
1.142(4)/1.137(4)
58.4(2)
1.510(10)/1.523(11)
1.545(11)/1.553(10)
1.451(11)/1.452(11)
1.161(10)/1.159(11)
58.4(5)
94.62(3)
96.75(3)
95.90(7)
Cg(1)eMeCg(2)
C1/11eC6/16eC9/19
C6/16eC9/19eC10/20
C9/19eC10/20eN1/2
C2/12eC1/11eC6/16-C9/19
C1/11eC6/16eC9/19eC10/20
qb
131.03(5)
129.07(5)
129.70(14)
109.7(2)/109.5(2)
111.8(2)/112.4(2)
178.4(3)/178.1(3)
138.1(2)/139.4(2)
176.3(2)/167.8(2)
ꢀ29.5
109.7(2)/109.8(2)
112.2(2)/112.4(2)
178.5(4)/177.8(4)
54.3(4)/53.9(4)
ꢀ169.1(3)/e176.2(2)
28.6
109.8(7)/108.4(6)
113.7(7)/111.8(6)
178.2(9)/176.8(10)
54.7(9)/54.0(9)
ꢀ168.6(6)/e175.6(6)
28.0
a
The ring planes are defined as follows: Cp(1) ¼ C(1e5), Cp(2) ¼ C(11e15) and Cg(1,2) are the respective ring centroids.
b
q
denotes the dihedral angle C1eCg(1)eCg(2)eC11.

J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
2367
Scheme 4. Methylation of dichloride 7 yielding compound 10.
reluctant to crystallization, sensitive to light, which decomposed
slowly over few days at room temperature in the solid state as well
as in solution. NMR spectra revealed the presence of methyl groups
s
-bonded to titanium, manifested by the signals at dH ꢀ0.18 ppm
and dC 45.6 ppm, respectively. In the IR spectrum, the ChN
stretching band was found at slightly higher energies (2287 cmꢀ1
)
compared to the parent complex. EI-mass spectrometry did not
provide satisfactory results, probably due to decomposition of
compound 10 at relatively low temperatures.
Motivated by known intermolecular reactions of the unsub-
stituted dimethyltitanocene with nitriles under thermal conditions
[11], we made attempts to perform a controlled thermolysis of 10 in
toluene-d8 at 80 ꢁC. Unfortunately, an intractable mixture of
products was observed by the NMR spectroscopy. However,
methane could be identified as one of the products, indicating the
expected route of thermolysis starting with CH4 elimination.
Group 4 bent metallocene complexes are also known to
generate stable cationic species e.g., by an abstraction of chloride
anion [12]. We tested this possibility by performing the reaction of
complex 7 with Li[B(C6F5)4] in CD2Cl2 (Scheme 5), which was
monitored in situ by the NMR spectroscopy. Very slow formation of
a supposed cationic complex 11 over few weeks was observed. A set
of signals attributable to an unsymmetrical compound appeared, in
which the resonances for both methyls of the CMe2 group, protons
of the methylene, and all four protons of the cyclopentadienyl
moiety are nonequivalent. Also a dramatic change in the shift of the
nitrile carbon to dC 180.5 ppm suggested an intramolecular coor-
Fig. 3. A view of the molecular structure of 9 (molecule 1) showing the atom labeling
scheme and displacement ellipsoids at the 30% probability level.
2.3. Reactivity of compounds 7 and 10
To investigate the reactivity of prepared metallocene dichlor-
ides, we tested alkylation reactions of compound 7 as a selected
example. First attempts to utilize two equivalents of methyllithium
failed, since it led to partial reduction of the titanium center and
intractable mixture of products was obtained. In contrast to these
disappointing results, methylation with methylmagnesium
bromide in THF resulted in a clean conversion of the dichloride to
the dimethyl derivative [(h5eC5H5) (h5eC5H4CMe2CH2CN)TiMe2]
(10, Scheme 4). This compound was isolated as an amorphous solid,
dination of the pendant arm in a
h
2-C,N-fashion [13]. ESI-MS
analysis of the mixture supported the formulation of 11 showing
abundant fragment of the complex cation, for which the observed
isotopic distribution corresponded to the calculated one.
Table 2
Another route to cationic complexes was probed starting with
complex 10. A methyl group abstraction using (Ph3C)[B(C6F5)4] [14]
yielded a new compound, which has been tentatively assigned to
structure 12 (Scheme 6). According to the NMR spectroscopy, the
nitrile group in 12 is not intramolecularly coordinated to the metal
ion (the CN resonance at dC 119.5 ppm). Also for 12 the ESI-MS
analysis confirmed the suggested ionic nature of the complex
showing fragments of the complex cation (either free or with one
water molecule, which was likely formed during the measurement
Selected distances and angles [in Å and ꢁ] for 7 and 9 (two symmetrically inde-
pendent molecules).a
Compound
7 (M ¼ Ti)
9 (M ¼ Zr; mol. 1) 9 (M ¼ Zr; mol. 2)
MeCg(1)
MeCg(2)
MeC
(1e15; range)
MeCl1
MeCl2
C1eC6
C6eC9
C9eC10
C10eN
:Cp(1),Cp(2)
Cl1eMeCl2
Cg(1)eMeCg(2) 131.41(7)
C1eC6eC9
C6eC9eC10
C9eC10eN
C2eC1eC6eC9
C1eC6-C9eC10
qb
2.088(2)
2.062(2)
2.231(2)
2.217(2)
2.237(2)
2.214(2)
2.321(4)e2.514(3) 2.445(4)e2.639(5) 2.465(4)e2.628(4)
2.3568(10)
2.3626(12)
1.528(5)
1.531(5)
1.471(6)
1.138(5)
54.9(2)
2.4368(13)
2.436(2)
1.530(6)
1.536(7)
1.481(7)
1.135(6)
55.1(3)
2.4472(14)
2.431(2)
1.524(6)
1.557(6)
1.489(7)
1.123(6)
56.3(2)
94.05(4)
98.76(7)
131.41(9)
108.8(4)
112.9(4)
179.2(5)
54.3(6)
99.03(6)
130.05(8)
109.2(4)
113.6(4)
178.2(5)
46.3(6)
109.6(3)
114.8(3)
178.0(4)
58.1(4)
ꢀ176.9(3)
25.8
ꢀ175.5(4)
179.7(4)
ꢀ35.7
ꢀ45.0
a
The ring planes are defined as follows: Cp(1) ¼ C(1e5), Cp(2) ¼ C(11e15) and Cg
(1,2) are the respective ring centroids.
Scheme 5. Proposed reaction pathway for the chloride anion abstraction by Li[B
(C6F5)4] in complex 7.
b
q
denotes the dihedral angle C1eCg(1)eCg(2)eC11.

2368
J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
a Nicolet Avatar FTIR spectrometer on Nujol suspensions between
KBr plates (prepared in a glovebox) in the range of 400e4000 cmꢀ1
.
Elemental analyses were performed on a FLASH 2000 CHN
elemental analyzer (Thermo Scientific). Melting points were deter-
mined on a Kofler apparatus, the values are uncorrected; samples
were sealed in glass capillaries under nitrogen.
4.2. Preparation of (C5H4CMe2CH2CN)Li (1)
n-Butyllithium (10.0 mL of 2.5
M solution in hexanes,
Scheme 6. Proposed reaction pathway for the methyl group abstraction by (Ph3C)[B
(C6F5)4] in complex 10.
25.0 mmol) was added dropwise to a stirred solution of acetonitrile
(1.31 mL, 25.0 mmol) in THF (30 mL) at ꢀ78 ꢁC. While the cooling
was maintained, the mixture was stirred for 15 min. Subsequently,
neat 6,6-dimethylfulvene (2.65 g, 25.0 mmol) was added dropwise.
The yellow-orange color of the added fulvene quickly changed to
pale yellow, indicating a formation of the product. After the addi-
tion was complete, the mixture was allowed to warm to room
temperature and stirred for 2 h. The solution was concentrated in
vacuo to ca. 5 mL and n-hexane (30 mL) was added, which led to
a formation of a brownish precipitate. The liquid phase was
removed and the solids were washed with n-hexane (10 mL), and
dried in vacuo. After ca 1 h at low pressure (5 ꢃ 10ꢀ2 Torr), the
precipitate turned into an oily residue (as the solvating THF was
being released) that later solidified to a brownish waxy solid,
identified as the lithium salt 1 by NMR spectroscopy. The air- and
moisture-sensitive product retained various amounts of THF, which
proved to be difficult to remove, but was of a sufficient purity to be
used for further reactions. Yield: 3.75 g (98%).
in contact with moisture). Unfortunately, in cases of both cationic
species 11 and 12, attempts to isolate these compounds have been
so far unsuccessful.
3. Conclusion
A
new nitrile-functionalized cyclopentadienyl ligand was
prepared in a straightforward manner by the fulvene route in the
form of its lithium salt. Its coordination to group 4 metals yielded
bent metallocene dichlorides, in which the pendant arms did not
interact with the metal center. Lower yields of titanium complex 2,
caused by the reducing ability of the lithium salt were overcome by
the sequential preparation of monocyclopentadienyl complex 6,
which was then converted to 2. Titanocene dichloride 7 was alky-
lated by the Grignard reagent to afford the corresponding dimethyl
derivative 10, while the nitrile functional group remained unaf-
fected. The reaction of 7 with Li[B(C6F5)4] provided a preliminary
evidence of formation of the cationic species with the intramo-
lecularly coordinated nitrile group. A methyl group abstraction in
10 using (Ph3C)[B(C6F5)4] also led to the formation of the corre-
sponding cationic complex, but in this case, the nitrile group did
not exhibit the intramolecular coordination according to the
spectral data. Further investigations into the reactivity of func-
tionalized metallocene complexes involving transformations of the
pendant group are currently in progress.
NMR (THF-d8) 1H:
d
1.34 (s, 6 H, CMe2), 2.49 (s, 2 H, CH2CN), 5.34
29.8
(m, 2 H, C5H4 distal), 5.39 (m, 2 H, C5H4 proximal). 13C{1H}:
d
(CMe2), 34.0 (CH2CN), 34.6 (CMe2),100.3 (C5H4 CH dist.),103.0 (C5H4
CH prox.), 120.2 (CN), 125.6 (C5H4 Cipso).
4.3. Preparation of [(h5eC5H4CMe2CH2CN)2TiCl2] (2)
A 1 M solution of TiCl4 in toluene (1.0 mL, 1.0 mmol) was added
to 10 mL of THF at ꢀ78 ꢁC, forming a bright yellow precipitate of
TiCl4$2THF. To the stirred suspension, a solution of lithium salt 1
(306 mg, 2.0 mmol) in THF (10 mL) was slowly introduced. The
color of the mixture immediately changed to deep red. After 15 min
at ꢀ78 ꢁC, the mixture was allowed to warm slowly to room
temperature and stirred for further 16 h. All volatiles were removed
under vacuum and the dark residue was extracted with toluene/
dichloromethane mixture (2:1 v/v, 3 ꢃ 10 mL). The combined
extracts were evaporated, redissolved in dichloromethane (5 mL),
filtered, and allowed to stand at ꢀ30 ꢁC overnight, affording deep
red crystals, which were separated from the solution, washed with
cold diethyl ether, and dried in vacuo. The mother liquor afforded
another crop of the product upon reducing the volume. Total yield
of 2: 107 mg (26%). Repeated runs gave similar results.
4. Experimental
4.1. Materials and methods
All syntheses and manipulations with air- and moisture-sensitive
compounds were performed under an argon atmosphere using
standard Schlenk techniques or in a glovebox Labmaster 130
(mBraun) under purified nitrogen. All solvents (including deuter-
ated) were appropriately dried: THF, diethyl ether, toluene, n-hexane
by refluxing with Na/benzophenone ketyl until blue color persisted,
then distilled under argon and stored over sodium mirror; chloro-
form, dichloromethane by refluxing with CaH2, acetonitrile by
refluxing with P2O5, then distilled under argon and stored over 4 Å
molecular sieves. 6,6-dimethylfulvene was prepared as described in
the literature [15]. Other chemicals were used as received from
commercial sources (Aldrich, Strem).
M.p. 162 ꢁC. NMR (CDCl3) 1H:
CH2CN), 6.46 (m, 2 H, C5H4 dist.), 6.55 (m, 2 H, C5H4 prox.). 13C{1H}:
28.5 (CMe2), 31.5 (CH2CN), 36.4 (CMe2), 114.8 (C5H4 CH dist.), 118.6
d 1.54 (s, 6 H, CMe2), 2.90 (s, 2 H,
d
(CN), 122.2 (C5H4 CH prox.), 143.9 (C5H4 Cipso). IR (Nujol): 3107 (m),
3100 (w), 2241 (w, nCN), 1492 (m), 1427 (w), 1418 (w), 1415 (w), 1395
(w), 1369 (m), 1319 (w), 1258 (w), 1141 (m), 1056 (w), 944 (w), 872
(s), 850 (s), 842 (m), 731 (w) cmꢀ1. EI-MS, m/z (relative abundance):
410 (6; [M]þꢂ), 375 (38; [MeCl]þ), 146 (85; [C5H4CMe2CH2CN]þ),
106 (100; [C5H4CMe2]þ). Anal. calc. for C20H24Cl2N2Ti (411.21): C
58.41, H 5.88, N 6.81%. Found: C 58.29, H 5.91, N 6.88%.
NMR spectrawere measured on a Varian Unity 300 spectrometer
at 293 K. Chemical shifts (d/ppm) are given relative to solvent signals
(CDCl3: dH 7.26, dC 77.16; CD2Cl2: dH 5.32, dC 53.84; THF-d8 dH 3.58, dC
67.21). The assignmentof NMR signals is based on 1D-NOESY, gCOSY,
gHSQC, and gHMBC experiments. EI-MS spectra were obtained on
a VG-7070E mass spectrometer at 70 eV. Electrospray (ESI) mass
spectra were measured with a Bruker Esquire 3000 instrument on
dichloromethane/acetonitrile solutions. GCeMS was performed on
a Thermo Focus DSQ machineusing the capillarycolumnThermoTR-
4.4. Preparation of [(h5eC5H4CMe2CH2CN)2ZrCl2] (3)
Lithium salt 1 (306 mg, 2.0 mmol) and ZrCl4 (233 mg, 1.0 mmol)
were placed in a Schlenk flask under argon and after cooling the
5MS (15 m ꢃ 0.25 mm ID ꢃ 0.25
mm). IR spectra were measured on

J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
2369
solids to ꢀ78 ꢁC, THF (30 mL) was slowly introduced. The suspension
was stirred, gradually warmed to room temperature over a period of
30 min. A clear yellow solution was obtained, which was further
stirred for 3 h. All volatiles were removed and the residue was
extracted with dichloromethane (3 ꢃ 10 mL), filtered, and evapo-
rated under vacuum. The crude product was recrystallized from THF/
diethyl ether at ꢀ30 ꢁC giving pale yellow crystals. Yield of 3: 236 mg
(52%).
the solvent, amber amorphous solid, which was triturated with n-
hexane to remove soluble impurities. The crude product thus
obtained was sufficiently pure according to the NMR spectroscopy.
Yield of 6: 523 mg (87%). Analytically pure sample was obtained by
sublimation (5 ꢃ 10ꢀ2 Torr, 150 ꢁC) as an orange solid, but signifi-
cant loss due to decomposition was observed.
6: M.p. 78 ꢁC. NMR (CDCl3) 1H:
CH2CN), 6.97 (m, 2 H, C5H4 dist.), 7.14 (s, 6 H, C5H4 prox.). 13C{1H}:
28.0 (CMe2), 32.9 (CH2CN), 36.5 (CMe2), 118.3 (CN), 121.1 (C5H4 CH
d 1.64 (s, 6 H, CMe2), 2.83 (s, 2 H,
M.p. 154 ꢁC. NMR (CDCl3) 1H:
CH2CN), 6.37 (m, 2 H, C5H4 dist.), 6.48 (m, 2 H, C5H4 prox.). 13C{1H}:
28.3 (CMe2), 32.6 (CH2CN), 35.7 (CMe2), 111.4 (C5H4 CH dist.), 117.5
d
1.53 (s, 6 H, CMe2), 2.74 (s, 2 H,
d
dist.), 123.8 (C5H4 CH prox.), 148.4 (C5H4 Cipso). IR (Nujol): 3111 (m),
3093 (w), 2250 (w, nCN),1482 (m),1419 (m),1397 (w),1307 (m),1293
(m), 1242 (m), 1056 (w), 984 (w), 851 (s), 844 (m) cmꢀ1. EI-MS, m/z
(relative abundance): 299 (25; [M]þꢂ), 264 (8; [MeCl]þ), 146 (91;
[C5H4CMe2CH2CN]þ), 106 (100; [C5H4CMe2]þ). Anal. calc. for
C10H12Cl3NTi (300.46): C 39.97, H 4.03, N 4.66%. Found: C 39.86, H
4.13, N 4.69%.
d
(C5H4 CH prox.), 118.4 (CN), 139.2 (C5H4 Cipso). IR (Nujol): 3100 (m),
2242 (w, nCN), 1488 (w), 1422 (w), 1416 (w), 1394 (w), 1388 (w), 1370
(m), 1319 (w), 1139 (m), 1045 (w), 945 (w), 860 (m), 835 (s), 820 (w),
665 (w) cmꢀ1. EI-MS, m/z (relative abundance): 452 (76; [M]þꢂ), 417
(37; [MeCl]þ), 306 (95; [MeC5H4CMe2CH2CN]þ), 265 (100). Anal.
calc. for C20H24Cl2N2Zr (454.53): C 52.85, H 5.32, N 6.16%. Found: C
52.72, H 5.38, N 6.22%.
4.7. Preparation of 2 from 6
4.5. Preparation of [(h5eC5H4CMe2CH2CN)2HfCl2] (4)
Lithium salt 1 (118 mg, 0.78 mmol) and complex 6 (233 mg,
0.78 mmol) were placed in a Schlenk flask under argon, cooled
to ꢀ78 ꢁC, and THF (15 mL) was slowly introduced with vigorous
stirring. The color of the mixture changed immediately to deep red.
After 10 min at ꢀ78 ꢁC, the mixture was allowed to warm slowly to
room temperature and stirred for further 4 h. Following the same
work-up procedure as described in the Section 4.3, complex 2 was
obtained. Yield: 218 mg (68%). Analytical data same as above.
Lithium salt 1 (306 mg, 2.0 mmol) and HfCl4 (320 mg, 1.0 mmol)
were placed in a Schlenk flask under argon and THF (30 mL) was
slowly introduced while cooling the reaction vessel to ꢀ78 ꢁC. The
suspension was stirred, gradually warmed to room temperature
over a period of 30 min. A clear orange solution was obtained, which
was further stirred for 4 h. All volatiles were removed and the
residue was extracted with toluene/dichloromethane mixture (1:1
v/v, 3 ꢃ10 mL), filtered, and concentrated under vacuum toca.10 mL.
The product crystallized from the solution at 4 ꢁC giving pale yellow
crystals, which were dried in vacuo. Yield of 4: 303 mg (56%).
4.8. Preparation of [(h5eC5H5) (h5eC5H4CMe2CH2CN)TiCl2] (7)
Lithium salt 1 (306 mg, 2.0 mmol) and [(h5eC5H5)TiCl3] (439 mg,
2.0 mmol) were placed in a Schlenk flask under argon, cooled
to ꢀ78 ꢁC, and THF (30 mL) was slowly introduced with stirring. The
suspension, which immediately turned red, was gradually warmed
to room temperature over a period of 30 min. The resulting clear red
solutionwas further stirred for 3 h. All volatiles were removed under
vacuum and the solid residue was extracted with toluene/
dichloromethane mixture (2:1 v/v, 3 ꢃ 10 mL). The combined
extracts were concentrated to ca. 5 mL and the product was allowed
to crystallize at ꢀ30 ꢁC overnight. Red crystals were separated from
the solution, washed with diethyl ether, and dried in vacuo. The
mother liquor afforded another crop of the product upon reducing
the volume. Combined yield: 541 mg (82%).
M.p. 135e140 ꢁC. NMR (CDCl3) 1H:
2 H, CH2CN), 6.26 (m, 2 H, C5H4 dist.), 6.39 (m, 2 H, C5H4 prox.). 13
{1H}:
28.3 (CMe2), 32.8 (CH2CN), 35.6 (CMe2), 110.2 (C5H4 CH dist.),
d 1.53 (s, 6 H, CMe2), 2.72 (s,
C
d
116.0 (C5H4 CH prox.), 118.4 (CN), 137.1 (C5H4 Cipso). IR (Nujol): 3102
(m), 2242 (w, nCN), 1489 (w), 1422 (w), 1416 (w), 1388 (m), 1319 (w),
1139 (m),1045 (w), 945 (w), 862 (m), 837 (s), 821 (w), 665 (w) cmꢀ1
.
EI-MS, m/z (relative abundance): 542 (7; [M]þꢂ), 396 (100;
[MeC5H4CMe2CH2CN]þ), 355 (99). Anal. calc. for C20H24Cl2N2Hf
(541.80): C 44.33, H 4.47, N 5.17%. Found: C 44.26, H 4.56, N 5.20%.
4.6. Preparation of [(h5eC5H4CMe2CH2CN)TiCl3] (6)
Me3SiCl (230 mg, 2.12 mmol) was added dropwise to a stirred
solution of lithium salt 1 (306 mg, 2.0 mmol) in THF (30 mL)
at ꢀ78 ꢁC. The mixture was slowly warmed to room temperature
and stirred for 18 h. The solvents were removed in vacuo and the
resulting pale yellow oil was dissolved in toluene (15 mL) and
filtered to another flask leaving a white precipitate of LiCl.
According to the NMR spectroscopy and GCeMS analysis, the oil
M.p. 168 ꢁC. NMR (CDCl3) 1H:
CH2CN), 6.47 (m, 2 H, C5H4 dist.), 6.58 (overlapping signals: m, 2 H,
C5H4 prox. and s, 5 H, C5H5). 13C{1H}:
28.6 (CMe2), 31.5 (CH2CN),
d 1.52 (s, 6 H, CMe2), 2.91 (s, 2 H,
d
36.3 (CMe2), 115.1 (C5H4 CH dist.), 118.7 (CN), 120.6 (C5H5), 121.6
(C5H4 CH prox.), 143.8 (C5H4 Cipso). IR (Nujol): 3105 (m), 2237 (w,
nCN), 1488 (m), 1448 (s), 1421 (m), 1382 (m), 1366 (m), 1316 (w),
1258 (w), 1139 (m), 1028 (m), 1017 (m), 947 (w), 873 (m), 860 (m),
830 (vs), 737 (w), 661 (w) cmꢀ1. EI-MS, m/z (relative abundance):
329 (40; [M]þꢂ), 294 (58; [MeCl]þ), 264 (68; [Me(C5H5)]þ),146 (92;
[C5H4CMe2CH2CN]þ), 106 (90; [C5H4CMe2]þ), 65 (100, [C5H5]þ).
Anal. calc. for C15H17Cl2NTi (330.10): C 54.58, H 5.19, N 4.24%.
Found: C 54.39, H 5.23, N 4.25%.
contained
predominantly
the
silylated
cyclopentadiene,
Me3SiC5H4CMe2CH2CN (5, >90% of this particular isomer), which
was directly used in the next step.
5: NMR (CDCl3): 1H:
d
ꢀ0.03 (s, 9 H, SiMe3), 1.36 (s, 6 H, CMe2),
2.51 (s, 2 H, CH2CN), 3.32 (m, 1 H, Me3SiCH), 6.18, 6.50, 6.57 (3ꢃ m,
1 H, C¼CH). 13C{1H}:
d
ꢀ1.93 (SiMe3), 28.0 (CMe2), 31.6 (CH2CN),
34.7 (CMe2), 51.4 (Me3SiC), 118.6 (CN), 126.2, 128.7, 135.1
(3 ꢃ C¼CH), 150.6 (Me3SiC5H4 Cipso). GCeMS, m/z (relative abun-
dance): 219 (3; [M]þꢂ), 163 (6), 113 (36), 73 (100; [SiMe3]þ).
The toluene solution of 5 (prepared as described above) was
slowly added to a stirred solution of TiCl4 in the same solvent
(2.0 mL of 1 M solution, 2.0 mmol) with cooling to ꢀ30 ꢁC. After
warming to room temperature, the mixture was stirred for 16 h and
subsequently evaporated under vacuum. The residue was extracted
with toluene (3 ꢃ 10 mL). The extracts afforded, upon removal of
4.9. Preparation of [(h5eC5H5) (h5eC5H4CMe2CH2CN)ZrCl2] (8)
In a similar manner as in the previous case, lithium salt 1
(153 mg, 1.0 mmol) and [(h5eC5H5)ZrCl3] (263 mg, 1.0 mmol) were
reacted at ꢀ78 ꢁC in THF (15 mL). The mixture was gradually
warmed to room temperature over a period of 30 min and the
resulting clear pale yellow solution was further stirred for 3 h. All
volatiles were removed under vacuum and the oily residue was
extracted with dichloromethane (3 ꢃ 10 mL). Evaporation of the

2370
J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
extracts afforded the crude product as a colorless oil that solidified
after standing at 4 ꢁC overnight. Recrystallization from dichloro-
methane/diethyl ether at ꢀ30 ꢁC afforded a colorless powder. Yield:
280 mg (75%).
in vacuo. The mother liquor afforded another crop of the product
upon reducing its volume. Combined yield: 754 mg (85%).
M.p. 176e178 ꢁC. NMR (CDCl3) 1H:
d
1.53 (s, 6 H, CMe2), 2.02 (s,
15 H, C5Me5), 2.82 (s, 2 H, CH2CN), 5.87 (m, 2 H, C5H4 dist.), 6.31 (m,
2 H, C5H4 prox.). 13C{1H}:
12.6 (C5Me5), 28.4 (CMe2), 32.2
M.p.109e110 ꢁC. NMR(CDCl3)1H:
d
1.53 (s, 6 H, CMe2), 2.78 (s, 2 H,
CH2CN), 6.38 (m, 2 H, C5H4 dist.), 6.49 (s, 5 H, C5H5), 6.50 (m, 2 H, C5H4
prox.). 13C{1H}:
28.3 (CMe2), 32.5 (CH2CN), 35.7 (CMe2), 111.6 (C5H4
d
(CH2CN), 35.6 (CMe2), 110.4 (C5H4 CH dist.), 118.0 (C5H4 CH prox.),
118.7 (CN), 124.8 (C5Me5), 139.0 (C5H4 Cipso). IR (Nujol): 3105 (w),
2237 (w, nCN), 1490 (m), 1414 (w), 1383 (m), 1319 (w), 1140 (m),
1025 (w), 946 (w), 872 (w), 814 (vs), 682 (w), 664 (w) cmꢀ1. EI-MS,
m/z (relative abundance): 441 (50; [M]þꢂ), 406 (11; [MeCl]þ), 306
(100; [Me(C10H15)]þ), 295 (83; [Me(C5H4CMe2CH2CN)]þ), 265
(94). Anal. calc. for C20H27Cl2NZr (443.55): C 54.15, H 6.14, N 3.16%.
Found: C 54.07, H 6.22, N 3.18%.
d
CH dist.), 116.3 (C5H5), 117.0 (C5H4 CH prox.), 119.0 (CN), 139.0 (C5H4
Cipso). IR (Nujol): 3110 (m), 3101 (m), 2239 (w, nCN),1487 (m),1442 (s),
1415 (m),1384 (m),1369 (m),1315 (w),1137 (w),1023 (m),1016 (m),
946 (w), 857 (m), 838 (s), 823 (vs), 664 (w) cmꢀ1. EI-MS, m/z (relative
abundance): 371 (25; [M]þꢂ), 336 (16; [MeCl]þ), 306 (90; [Me
(C5H5)]þ), 265 (100), 225 (90, [Me(C5H4CMe2CH2CN)]þ). Anal. calc.
for C15H17Cl2NZr (373.42): C 48.24, H 4.59, N 3.75%. Found: C 48.12, H
4.62, N 3.81%.
4.12. Preparation of [(h5eC5H5) (h5eC5H4CMe2CH2CN)TiMe2] (10)
4.10. Attempted preparation of [(h5eC5H5) (h5eC5H4CMe2CH2CN)
HfCl2]
The following synthesis was performed in the dark. Methyl-
magnesium bromide (0.9 mL of 1 M solution in dibutyl ether,
0.9 mmol) was added dropwise to a stirred solution of compound 7
(149 mg, 0.45 mmol) in THF (10 mL) at ꢀ78 ꢁC. The mixture was
gradually warmed to room temperature, while the color slowly
changed from deep red to orange, and the stirring was maintained
for 3 h. All volatiles were removed in vacuo and the yellow residue
was extracted with toluene/n-hexane mixture (3:2 v/v, 5 ꢃ 5 mL) in
order to thoroughly separate the product from inorganic salts. The
combined extracts were evaporated to leave a yellow amorphous
solid. Yield: 116 mg (89%). NOTE: The compound seems to be light
sensitive. It gradually decomposes even in dark in a few days at
room temperature when in the solid state and even faster in
solution, but can be stored at ꢀ30 ꢁC at least for weeks.
A similar procedure as for complex 7 (Section 4.8) was applied
starting from 1 (153 mg, 1.0 mmol) and [(h5eC5H5)HfCl3] (350 mg,
1.0 mmol). After 16 h, still about half of the trichloride remained
unreacted, therefore heating to 60 ꢁC was applied for additional
18 h. NMR spectroscopy revealed
a mixture of complexes
[(h5eC5H5)2HfCl2], [(h5eC5H5) (C5H4CMe2CH2CN)HfCl2], and 4 in
ca. 2:2:1 ratio (because of an extensive overlap of the signals, it was
difficult to exactly determine the molar ratio). Colorless crystals of
[(h5eC5H5)2HfCl2] were isolated by crystallization from dichloro-
methane, further attempts to separate the mixture failed.
[(h5eC5H5) (C5H4CMe2CH2CN)HfCl2]: NMR (CDCl3) 1H:
d 1.54 (s,
6 H, CMe2), 2.73 (s, 2 H, CH2CN), 6.27 (m, 2 H, C5H4 dist.), 6.39
(overlapping signals: m, 2 H, C5H4 prox. and s, 5 H, C5H5).
NMR (THF-d8) 1H:
(s, 2 H, CH2CN), 5.97 (m, 2 H, C5H4 dist.), 6.06 (s, 5 H, C5H5), 6.21 (m,
2 H, C5H4 prox.). 13C{1H}:
27.7 (CMe2), 33.2 (CH2CN), 35.5 (CMe2),
d
ꢀ0.18 (s, 6 H, TiMe2), 1.22 (s, 6 H, CMe2), 2.48
d
4.11. Preparation of [(h
5-C5Me5) (h5eC5H4CMe2CH2CN)2ZrCl2] (9)
45.6 (TiMe2), 111.3 (C5H4 CH dist.), 114.5 (C5H5), 114.9 (C5H4 CH
prox.), 118.3 (CN), 135.4 (C5H4 Cipso). IR (Nujol): 3091 (w), 2287 (w,
nCN), 1487 (w), 1418 (w), 1306 (w), 1180 (m), 1140 (m), 1023 (m), 879
(w), 820 (vs), 723 (w) cmꢀ1. Anal. calc. for C17H23NTi (289.26): C
70.58, H 8.01, N 4.84%. Found: C 69.53, H 8.32, N 4.64%.
Following the same procedure as for the preparation of 7 (Section
4.8), lithium salt 1 (306 mg, 2.0 mmol) and [(
5-C5Me5)ZrCl3]
h
(666 mg, 2.0 mmol) were mixed at ꢀ78 ꢁC with THF (30 mL) and
stirred for 3 h at room temperature. After removing the solvents
under vacuum, the orange residue was extracted with toluene
(3 ꢃ 10 mL). The combined extracts were concentrated to ca. 5 mL
and the product was allowed to crystallize at ꢀ30 ꢁC overnight. Light
yellowcrystals were separated, washed with diethyl ether, and dried
4.13. Reaction of 7 with Li[B(C6F5)4]
Complex 7 (16 mg, 0.05 mmol) and Li[B(C6F5)4]$2.5Et2O (44 mg,
0.05 mmol) were placed into a Schlenk tube under argon and
Table 3
Selected crystallographic data for 2, 3, 4, 7, and 9.
Compound
2
3
4
7
9
Formula
C20H24Cl2N2Ti
411.21
C20H24Cl2N2Zr
454.53
C20H24Cl2N2Hf
541.80
C15H17Cl2NTi
330.10
C20H27Cl2NZr
443.55
M (g molꢀ1
)
Crystal system
Space group
a (Å)
Orthorhombic
P212121 (no. 19)
7.3411(2)
14.9654(3)
17.7994(5)
90
1955.49(9)
4
1.397
Orthorhombic
P212121 (no. 19)
7.43860(10)
15.0201(3)
18.0693(4)
90
2018.86(7)
4
1.495
Orthorhombic
P212121 (no. 19)
7.4293(4)
15.0096(7)
18.0116(5)
90
2008.49(15)
4
1.792
Monoclinic
P21 (no. 4)
6.6785(6)
11.4021(9)
10.1469(5)
107.524(5)
736.82(10)
2
Monoclinic
P21/n (no. 14)
18.2406(8)
12.1165(4)
18.3373(7)
96.919(2)
4023.3(3)
8
b(Å)
c (Å)
b
(ꢁ)
V (Å3)
Z
Dcalc (g mLꢀ1
)
1.488
1.465
Diffractions total
28700
4472/3436
6.6
37016
4623/3866
5.7
14391
4579/3336
9.1
10970
3341/2694
7.4
32650
9047/6115
3.7
4.65
8.38, 12.31
e
Unique/observeda diffractions
Rint (%)b
R (observed data) (%)c
R, wR (all data) (%)c
Flack’s parameter
3.58
3.22
4.19
4.35
6.09, 7.63
ꢀ0.03(3)
0.30, ꢀ0.32
4.73, 7.02
ꢀ0.02(4)
0.69, ꢀ0.53
7.96, 7.73
ꢀ0.027(13)
2.03, ꢀ1.99
6.14, 10.05
ꢀ0.01(3)
0.37, ꢀ0.71
Dr (e Åꢀ3
)
1.11, ꢀ0.89
a
Diffractions with Io > 2s(Io).
b
c
2
Rint ¼ SrFo ꢀ Fo2(mean)r/SFo2, where Fo2(mean) is the average intensity of symmetry-equivalent diffractions.
R ¼ SrrFor ꢀ rFcrr/SrFor, wR ¼ [S{w(Fo ꢀ Fc2)2}/Sw(Fo2)2]1/2
.
2

J. Pinkas et al. / Journal of Organometallic Chemistry 696 (2011) 2364e2372
2371
CD2Cl2 (ca. 0.6 mL) was condensed into the tube at liquid nitrogen
temperature under vacuum. After warming the mixture to room
temperature, a clear red solution was formed, which was trans-
ferred into the NMR tube, cooled to liquid nitrogen temperature
and flame-sealed under vacuum. The reaction was in situ periodi-
cally monitored by NMR. Over several days, a set of signals started
to appear in the spectrum, while the starting compound was being
consumed. Simultaneously, a small amount of white precipitate
(LiCl) appeared in the tube. After one month, approximately 1:1 M
ratio was reached. The new compound was tentatively assigned to
structure 11. Attempts to isolate this compound have been so far
unsuccessful.
(SHELXL97, Ref. [18]). Non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogen atoms were
included in their calculated positions and treated as riding atoms
with Uiso(H) assigned to a multiple of Ueq of their bonding carbon
atom. Selected crystallographic data are given in Table 3. Geometric
parameters and structural drawings were obtained with a recent
version of the Platon program [19].
Acknowledgments
This work was financially supported by the Czech Science
Foundation (grant no. GPP207/10/P200) and is a part of the
research project supported by the Ministry of Education, Youth and
Sports of the Czech Republic (no. LC06070). The authors thank Dr.
Lidmila Petrusová for the determination of melting points.
NMR (CD2Cl2) 1H:
d
1.17, 1.34 (2ꢃ s, 3 H, CMe2), 2.42, 2.82 (2ꢃ d,
2J ¼ 15.3 Hz, 1 H, CH2CN), 6.02, 6.25 (2ꢃ m, 1 H, C5H4), 6.65 (s, 5 H,
C5H5), 6.77, 7.14 (2ꢃ m, 1 H, C5H4). 13C{1H}:
d
27.9, 28.5 (2ꢃ CMe2),
34.2 (CMe2), 46.2 (CH2CN), 108.9, 117.6, 120.8 (3ꢃ C5H4 CH), 122.2
(C5H5), 126.9 (C5H4 CH), 148.3 (C5H4 Cipso), 180.5 (CN); signals for
the free [B(C6F5)4]ꢀ anion: 136.6 (dm, JC,F ¼ 246 Hz, m-C6F5), 138.6
(dm, JC,F ¼ 246 Hz, p-C6F5), 148.4 (dm, JC,F ¼ 241 Hz, o-C6F5) ppm,
Cipso of C6F5 not observed. MS, m/z (ESIþ): 312 ([McationþH2O]þ),
294 ([Mcation]þ); (ESIe): 679 ([B(C6F5)4]ꢀ).
Appendix. Supplementary material
Views of the molecular structures of compounds 3 and 4 are
enclosed. CCDC-807693 (for compound 2), -807694 (3), -807695
(4), -807696 (7), and -807697 (9), respectively, contain the
supplementary crystallographic data in cif format. The data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
4.14. Reaction of 10 with (Ph3C)[B(C6F5)4]
Complex 10 (30 mg, 0.10 mmol) and (Ph3C)[B(C6F5)4] (96 mg,
0.10 mmol) were placed into a Schlenk tube under argon and C6D6
(1.0 mL) was added at room temperature with stirring. Amber oil
separated from a yellowish solution after several minutes. The
solution was removed and analyzed by the NMR spectroscopy,
which revealed the presence of Ph3CMe (dH 2.10 (s, 3 H, CMe),
7.05e7.20 (m, 15 H, Ph3C)). The oil was washed once with toluene
and redissolved in THF-d8. The identity of cationic complex 12 was
proposed based on NMR and MS data. Attempts to crystallize the
complex failed. The compound gradually decomposed at room
temperature in chlorinated solvents.
Appendix. Supplementary data
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2011.02.032.
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