Reduction-induced double bond coordination and multiple C-H activation in fully-substituted titanocenes bearing a pendant double bond or an eight-membered hydrocarbyl ansa-chain

Article abstract of DOI:10.1016/S0022-328X(02)02162-9

Reduction of isomeric, fully-substituted titanocene dichlorides having a pendant double bond, the presence of bis(trimethylsilyl)ethyne (btmse) affords different products depending on the alkenyl chain length. Whereas the reduction of 1 yields a compound with intramolecularly η²-coordinated double bond, [Ti(η⁵-C₅Me₅) {η²:η⁵-C₅Me₄ (CH₂CH₂CH=CH₂)}] (3), compound 2 affords under identical conditions a product with two new Ti-C bonds, [Ti{(η¹:η¹:η⁵- C₅Me₃(CH₂)(CH(Me)CH₂ CH₂)}(η⁵-C₅Me₅)] (4). The formation of 3 can be rationalized as a simple intramolecular stabilization of a titanocene intermediate formed by reductive removal of the chloride ligands. The formation of 4 from the respective titanocene, however, requires formally an activation (oxidative addition) of one C-H bond at the methyl group adjacent to the unsaturated chain followed by a hydrogen shift (hydrometallation). Under similar conditions, the complex with asymmetric unsaturated ansa-bridge [TiCl₂{η⁵:η⁵-C₅ Me₄CH₂CH=CH(CH₂)₅C ₅Me₄}] (5) is reduced to a titanocene-η²-alkene complex with the double bond shifted to the central position, ansa-[Ti{η²:η ⁵:η⁵-C₅Me₄ (CH₂)₃CH=CH(CH₂) ₃C₅Me₄}] (7). In the absence of btmse, analogous complex with saturated bridge ansa-[TiCl₂{η⁵:η⁵ -C₅Me₄(CH₂)₈C ₅Me₄}] (6) undergoes a hydrogen abstraction to give 7 as well albeit in a lower yield. The reduction of 6 in the presence of btmse gives η²-alkyne complex ansa-[Ti{η⁵:η⁵-C₅Me₄ (CH₂)₈C₅Me₄} (η²-Me₃SiC≡CSiMe₃)] (8) which is converted upon thermolysis at 150 °C to a mixture of asym- and sym-isomers of the doubly tucked-in complex ansa-[Ti{(η³:η⁴-C₅Me₂ (CH₂)₂)(CH₂)₈ (η⁵-C₅Me₄)}] (9) in 2:1 ratio; no C-H activation involving methylene groups of the ansa tether was observed. The crystal structures of 4, 7, and 8 have been determined by X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(02)02162-9

Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
www.elsevier.com/locate/jorganchem
Reduction-induced double bond coordination and multiple CÃ
/
H
activation in fully-substituted titanocenes bearing a pendant double
bond or an eight-membered hydrocarbyl ansa-chain
a
b
a
b
ˇ
Michal Hora´cˇek , Petr Steˇpnicˇka , Jirˇ´ı Kubisˇta , Ivana C´ısarˇova´ ,
Lidmila Petrusova´ a, Karel Mach a,*
a J. Heyrovsky´ Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejsˇkova 3, 182 23 Prague 8, Czech Republic
b Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
Received 26 July 2002; received in revised form 29 November 2002; accepted 2 December 2002
Abstract
Reduction of isomeric, fully-substituted titanocene dichlorides having a pendant double bond, [TiCl2(h5-C5Me4R)(h5-C5Me5)]
(RꢀCH2CH2CHÄCH2 (1); RꢀCH(Me)CHÄCH2, (2)), with magnesium in THF in the presence of bis(trimethylsilyl)ethyne
(btmse) affords different products depending on the alkenyl chain length. Whereas the reduction of 1 yields a compound with
intramolecularly h2-coordinated double bond, [Ti(h5-C5Me5){h2:h5-C5Me4(CH2CH2CHÄ
CH2)}] (3), compound 2 affords under
identical conditions a product with two new TiÃ
C bonds, [Ti{(h1:h1:h5-C5Me3(CH2)(CH(Me)CH2CH2)}(h5-C5Me5)] (4). The
/
/
/
/
/
/
formation of 3 can be rationalized as a simple intramolecular stabilization of a titanocene intermediate formed by reductive removal
of the chloride ligands. The formation of 4 from the respective titanocene, however, requires formally an activation (oxidative
addition) of one CÃ
Under similar conditions, the complex with asymmetric unsaturated ansa-bridge [TiCl2{h5:h5-C5Me4CH2CHÄ
(5) is reduced to a titanoceneꢁ
h2-alkene complex with the double bond shifted to the central position, ansa-[Ti{h2:h5:h5-
C5Me4(CH2)3CHÄ
CH(CH2)3C5Me4}] (7). In the absence of btmse, analogous complex with saturated bridge ansa-[TiCl2{h5:h5-
C5Me4(CH2)8C5Me4}] (6) undergoes a hydrogen abstraction to give 7 as well albeit in a lower yield. The reduction of 6 in the
presence of btmse gives h2-alkyne complex ansa-[Ti{h5:h5-C5Me4(CH2)8C5Me4}(h2-Me3SiCÅ
CSiMe3)] (8) which is converted upon
thermolysis at 150 8C to
mixture of asym- and sym-isomers of the doubly tucked-in complex ansa-[Ti{(h3:h4-
C5Me2(CH2)2)(CH2)8(h5-C5Me4)}] (9) in 2:1 ratio; no CÃ
H activation involving methylene groups of the ansa tether was observed.
/H bond at the methyl group adjacent to the unsaturated chain followed by a hydrogen shift (hydrometallation).
/CH(CH2)5C5Me4}]
/
/
/
a
/
The crystal structures of 4, 7, and 8 have been determined by X-ray crystallography.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Titanium; Titanocene; ansa-Titanocenes; Pendant double bonds; Alkene complexes; CÃH activation; X-ray crystallography
/
1. Introduction
hydrogen abstraction from the cyclopentadienyl ligand
with the central atom affording, for instance, a singly
tucked-in titanocene hydride [TiH(h5-C5Me5){h1:h5-
C5Me4(CH2)}] from decamethyltitanocene [Ti(h5-
C5Me5)2] [2]. Upon heating, the hydride further elim-
inates dihydrogen to give Ti(III) complex [Ti(h5-
C5Me5){h1:h5-C5Me4(CH2)}] [2c,3]. The latter com-
pound can be conveniently obtained by thermolysis of
[TiMe(h5-C5Me5)2] with liberation of methane [3,4] and
also by other methods [5]. An elimination of two
methane molecules from [TiMe2(h5-C5Me5)2] gives a
Electron-deficient titanocenes (14 valence electrons)
resulting from a reduction of highly methylated titano-
cene dichlorides by magnesium or alkali metals, or from
dealkylation of dialkyltitanocenes tend to rearrange by
various ways in order to increase the valence electron
count [1]. Rearrangements are usually initiated by
* Corresponding author. Tel.: ꢂ
2307.
E-mail address: mach@jh-inst.cas.cz (K. Mach).
/
42-286-58-5367; fax: ꢂ42-286-58-
/
doubly CÃ
/
H activated compound [Ti(h5-C5Me5){h3:h4-
C5Me3(CH2)2}] [4].
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(02)02162-9

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
155
Fully substituted titanocenes can be stabilized by
coordination of internal alkynes and alkenes [1]. A great
attention has been paid to their complexes with bis(tri-
methylsilyl)ethyne (btmse), which represents a good
leaving, bulky ligand capable of stabilizing highly
reactive titanocenes by means of a strong back-bonding
interaction. The h2-btmse complexes thus represent an
excellent source of the reactive titanocenes allowing to
study interactions of the latter with various substrates
[6,7]. Of the analogous h2-alkene complexes, well-
characterized are complexes of fully alkyl-substituted
titanocenes with ethene [8,9]. The use of pendant four-
alkenyl substituents, however, opens a wide range of
applications in catalysis and synthesis. While the pre-
sence of pendant double bonds in cationic alkene
polymerization catalysts [10] did not show any dramatic
effect on the polymerization of ethene, propene [11] and
styrene [12], the pendant double bonds were used to
modify the catalyst indirectly. Among other, the pen-
dant double bonds were utilized to anchor the catalysts
onto inorganic or polymeric matrices [13] and to bind
Lewis acid B(C6F5)2 group in a proximity of the metal
center via hydroboration with HB(C6F5)2 [10b,10c]. In
addition, bis(4-alkenylcyclopentadienyl) or ansa-bis{(4-
alkenyl)indenyl}metallocene dichlorides undergo reduc-
tive cyclization affording cyclopentadienyl ring-tethered
metallacyclopentanes [14] which can be conveniently
converted to ansa-metallocene dichlorides bridged by
long carbon chains [14a,15].
lent). A lower amount of lithium alkenylcyclo-
pentadienides was used because, in our hands, the use
of equimolar amounts resulted in mixtures containing
all the possible isomers, [TiCl2(h5-C5Me5)2], [TiCl2(h5-
C5Me4R)(h5-C5Me5)], and [TiCl2(h5-C5Me4R)2], whose
separation by crystallization was ineffective. By using a
substoichiometric amount of the alkenylcyclopentadie-
nides, the formation of the bis(alkenylcyclopentadienyl)
compounds was eliminated albeit the yields of titanium
products were lower (for a review on the synthesis of
mixed ligand titanocene dihalides see ref. [16]). The
obtained mixtures of [TiCl2(h5-C5Me5)2] with 1 or 2
(approximate molar ratios 21:79 and 27:73, respectively)
could not be separated by fractional crystallization,
however, the admixture of [TiCl2(h5-C5Me5)2] did not
hamper the reduction-induced reactions of 1 or 2; after
reducing the mixtures, products 3 and 4 were easily
separated from the less soluble byproduct [Ti(h5-
C5Me5)2(h2-Me3SiCÅ
tion from hexane. Thus, the reduction of 1ꢁ
/
CSiMe3)] by fractional crystalliza-
/
[TiCl2(h5-
C5Me5)2] mixture with magnesium in THF in the
presence of btmse followed by removal of [Ti(h5-
C5Me5)2(h2-btmse)] afforded yellow complex [Ti(h5-
C5Me5)(h2:h5-C5Me4(CH2CH2CHÄ
/
CH2)] (3) as the
only isolated product (Scheme 1). Its structure was
established from EIMS spectra showing [Mꢂ+] at m/z
358 as the base peak and from 1H- and 13C-NMR
spectra. The NMR spectra proved the presence of a
double bond p-coordinated to Ti(II) center. Three
In this contribution, we report on the products
formed during magnesium reduction from isomeric
titanocene dichlorides bearing only one pendant double
proton resonances due to the CHÄ
the range dH 1.72ꢁ2.72 and, particularly, the carbon
chemical shifts dC 102.5 (ÄCH2) and 128.7 (ÃCHÄ) are
/
CH2 group spanning
/
/
/
/
bond, [TiCl2(h5-C5Me4R)(h5-C5Me5)] (Rꢀ
CHÄCH2 (1); RꢀCH(Me)CHÄ
ansa-titanocene dichlorides having eight-membered un-
saturated, CH(CH2)5-
/CH2CH2-
typical for p-coordinated double bonds. Similar char-
acteristics were observed for h2-C2H4 in [Ti(h5-
C5Me5)2(h2-C2H4)] (dH 2.02, dC 105.1) [8] and [Ti{h5-
/
/
/CH2 (2)), and from
[TiCl2{h5:h5-C5Me4CH2CHÄ
/
C5Me4}] (5) and saturated bridges, [TiCl2{h5:h5-
C5Me4(CH2)8C5Me4}] (6). Different products of hydro-
gen abstraction arising from the reduction of 6 and from
thermolysis of [Ti{h5:h5-C5Me4(CH2)8C5Me4}(h2-
Me3SiCÅ
/
CSiMe3)] (8) are also described.
2. Results and discussion
2.1. Reactions of titanocenes containing pendant double
bonds
The starting titanocene dichlorides [TiCl2{h5-
C5Me4(CH2CH2CHÄ
/
CH2)}(h5-C5Me5)] (1) and race-
/
mic
[TiCl2{h5-C5Me4(C(Me)CHÄ
CH2)}(h5-C5Me5)]
(2) were prepared in one pot by consecutive metathesis
of [TiCl3(THF)3] with Li[C5Me5] (one equivalent) and
the respective Li[C5Me4R] (0.89 equivalent), followed by
oxidation of the formed chloro-bis(cyclopentadienyl)ti-
tanium(III) intermediate with PbCl2 (0.50 mol equiva-
Scheme 1.

156
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
C5Me4(SiMe3)}2(h2-C2H4)] (dH 2.34, dC 104.3) [9], for
h2-CHÄCH2 motif in [Ti(h5-C5Me4SiMe2CHÄ
CH2)-
(h2:h5-C5Me4SiMe2CHÄ
CH2)] (dH 0.88, 1.37 and 3.25,
dC 88.9 and 105.5) [17], and for an asymmetric h2-CHÄ
Table 1
˚
Selected bond distances (A) and bond angles (8) for 4
/
/
/
Bond lengths
a
/
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
/
Cg(1)
2.014(2)
2.284(2)
2.334(2)
2.472(2)
2.396(2)
2.406(2)
2.264(2)
1.519(2)
1.410(6)
1.533(3)
CH moiety in [Ti(II){h5:h2-C5Me3(CH2CH(t-Bu)CHÄ
/
/C(1)
CHCH(t-Bu)CH2)}(h5-C5Me5)] dH (1.32 and 2.77, dC
119.4 and 122.5) [18]. The presence of p-coordinated
double bond is also manifested by an absorption band at
970 nm in electronic absorption spectra which appears
at virtually the same position for h2-coordinated alkenes
[9,17,18] and internal alkynes [9,19].
/C(3)
/C(5)
/
C(11)
C(13)
C(6)
/
/
C(1)Ã
/C(20)
C(3)Ã
C(20)ÃC(21)
Cring
Cring
/C(4)
/
An analogous reduction and work-up in the case of
Ã
Ã
/
Cring
CMe
1.410(2)ꢁ
/
1.450(2)
1.511(2)
the 2ꢁ
[TiCl2(h5-C5Me5)2] mixture gave a different
/
/
1.499(2)ꢁ
2.065(2)
2.129(2)
2.515(2)
2.391(2)
2.413(2)
2.355(2)
2.190(2)
1.440(2)
1.400(6)
1.526(3)
1.531(3)
/
product which was characterized as [Ti{h1:h1:h5-
C5Me3(CH2)(CH(Me)CH2CH2)}(h5-C5Me5)] (4) by X-
ray diffraction analysis and NMR and MS spectroscopy
(Scheme 1). The carbon resonance at dC 79.4 due to the
tucked-in methylene carbon falls into the range observed
for singly and doubly tucked-in titanocenes
[2,4,19a,19c,19d] whilst that of titanium-bonded meth-
ylene group of the 1-methylprop-3-yl bridge (dC 69.3) is
a
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
TiÃ
/
Cg(2)
/
C(2)
/
C(4)
/
C(10)
C(12)
C(14)
C(22)
/
/
/
C(2)Ã
C(4)Ã
C(21)Ã
C(20)Ã
/C(6)
/C(5)
/C(22)
close to the upper limit for the values reported for s-TiÃ
/
/C(23)
C bonds [2,4a,5,17,20]. Compound 4 is thermally stable,
showing the molecular ion m/z 358 as the base peak in
EIMS spectra.
Bond angles
Cg(1)ÃTiÃCg(2)
C(2)ÃTiÃC(6)
C(21)ÃC(22)Ã
C(1)ÃC(20)ÃC(21)
C(6)ÃTiÃC(22)
C(2)ÃC(6)ÃTi
C(20)ÃC(21)Ã
/
/
144.6(1)
38.11(7)
115.0(1)
109.0(2)
92.67(8)
65.87(9)
109.5(2)
29.4(1)
/
/
/
/
Ti
/
/
2.2. The crystal structure of 4
/
/
/
/
A view of the molecular structure is shown in Fig. 1
and the selected geometric parameters are listed in Table
/
/C(22)
b
f
1. The cyclopentadienyl ring C(1ꢁ5) which is doubly
tethered to the titanium atom via methylene and 1-
methylprop-3-yl groups does not differ from the un-
/
a
Cg(1) and Cg(2) denote the centroids of the C(1ꢁ
/
5) and C(10ꢁ14)
/
cyclopentadienyl rings, respectively.
b
Dihedral angle subtended by the cyclopentadienyl least-squares
planes.
touched cyclopentadienyl ring C(10ꢁ
/
14) in the bond
Cg(1) distance
2.014(2) A is observably shorter than the TiÃCg(2)
lengths and angles. However, the TiÃ
/
˚
/
˚
distance of 2.065(2) A [Cg(1) and Cg(2) are centroids of
the C(1ꢁ5) and C(10ꢁ14) rings, respectively], and the
C(1ꢁ5) ring is tilted from a position perpendicular to the
TiÃCg(1) vector so that the TiÃC(2) distance (2.129(2)
A) is the shortest and the TiÃC(4) distance the longest
one (2.515(2) A). This tilt apparently reflects a con-
straint imposed by the methyleneÃtitanium bond (cf.
TiÃC(6) 2.264(2) vs. TiÃC(22) 2.190(2) A). As a con-
sequence, the methylene C(6) atom is declined from the
/
/
/
/
/
˚
/
˚
/
˚
/
/
˚
least-squares ring plane by as much as 0.900(3) A. On
the other hand, the bridge atom C(20) does not deviate
from the ring plane and the bond lengths and angles in
the 1-methylprop-1,3-diyl bridge do not depart from the
values typical for sp3 carbon atoms. The cyclopentadie-
nyl rings are in a close-to-staggered conformation (Fig.
2) and the respective dihedral angle (f) of 29.4(1)8
corresponds well to that in the simple tucked-in
compound [Ti(h5:h1-C5Me4CH2)(h5-C5Me5)] [5].
Fig. 1. The molecular structure of 4 (30% probability thermal motion
ellipsoids) showing the atom labeling scheme. Hydrogen atoms were
omitted for clarity.

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
157
presence of the p-coordinated double bond is manifested
by the presence of the electronic absorption band at
1000 nm, which is typical for titanocenes coordinating
internal alkynes and alkenes in the h2-fashion [9,17ꢁ
/
19].
The position of the absorption band in both titanoceneꢁ
alkene and titanoceneꢁalkyne complexes falls into the
region 920ꢁ1050 nm (cf. compounds 7: lmax 940 nm,
/
/
/
and 8: lmax 910 nm, see below) and fits to the concept of
back-bonding interaction outlined by Lauher and Hoff-
mann [21]. The formation of 7 requires a reductive
removal of both chloride ligands from 5 and 6 with
magnesium, which was used in excess, followed by a
double bond isomerization in the intermediate resulting
from 5, or an abstraction of two hydrogen atoms in an
intermediate arising from 6. Since no gas was evolved
during the reduction reaction, the hydrogen abstraction
by titanium(II) and their transfer to either THF or,
more likely, to magnesium under formation of chlor-
omagnesium hydrides should be considered. An evolu-
tion of hydrogen was observed when degassed water was
added to the mother liquor remaining after crystal-
lization of 7, however, this cannot be considered an
unequivocal evidence for magnesium hydride species to
be involved in the hydrogen transfer because the
decomposition of water with Ti(II) compounds is also
Fig. 2. A view of the molecular structure of 4 in the Cg(1)ÃCg(2)
/
direction.
2.3. Reactions of ansa-bridged titanocenes
Reduction of a mixture of ansa-bridged titanocene
ansa-[TiCl2{h5:h5-C5Me4CH2CHÄ
dichlorides
CH(CH2)5C5Me4}]
/
(5)
and
ansa-[TiCl2{h5:h5-
C5Me4(CH2)8C5Me4}] (6) (5:6 molar ratio ca.ꢀ
/
2:5)
[14a] with magnesium in THF at 60 8C affords the
ansa-titanocene complex with an h2-coordinated double
bond located in the center of the eight-membered bridge,
ansa-[Ti{h5:h5-C5Me4(CH2)3CHÄ
/CH(CH2)3C5Me4}]
well known [1]. In all cases, titanocene(TiIII) hydrideꢁ
magnesium hydride complexes of the TiÃMgÃTi or TiÃ
MgÃMgÃTi types which are easily recognized by ESR
spectroscopy were not detected [22].
/
(7), in 71% isolated yield (Scheme 2). A similar reduction
reaction performed with enriched 6 (6:5 ratio 95:5)
yielded 7 in 54% yield whereas the reduction of enriched
5 (5:6 ratio ca. 95:5) [15] gave the same product in 88%
yield. Yellow crystalline complex 7 was analyzed by
EIMS spectroscopy and its structure was further corro-
borated by single-crystal X-ray diffraction analysis. The
/
/
/
/
/
Another mode of stabilization of the plausible ansa-
titanocene intermediate was encountered during the
thermolysis of ansa-[Ti{h5:h5-C5Me4(CH2)8C5Me4}-
Scheme 2.

158
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
(h2-Me3SiCÅ
/
CSiMe3)] (8). The parent diamagnetic
complex 8 was obtained quantitatively by reduction of
6 with excess magnesium in THF in the presence of
btmse [6,19], and identified by 1H- and 13C-NMR,
EIMS, IR and UVꢁnear IR spectra as well as by single
/
crystal X-ray diffraction analysis. The presence of the
triple bond h2-coordinated to Ti(II) is indicated by its
13C-NMR signal occurring at dC 248.3 which is close to
the values found for [Ti(h5-C5HMe4)2(h2-btmse)] (dC
248.4) and [Ti(h5-C5Me5)2(h2-btmse)] (dC 248.5) [19a].
Likewise, the IR absorption bands due to the coordi-
nated triple bond in 8 at 1594 and 1558 cmꢃ1 are found
very close to the absorption bands of [Ti(h5-
C5Me5)2(h2-btmse)] (1595 and 1562 cmꢃ1) and the
electronic absorption band at 910 nm is virtually
identical with that of the latter complex (916 nm)
[19a]. EIMS spectra of 8 do not show the molecular
ion as the complex very likely dissociates into btmse and
ansa-titanocene which subsequently looses hydrogen(s)
even more easily than the corresponding titanocenes
generated from the above mentioned methyl-substituted
Fig. 3. The molecular structure of 7 (30% probability thermal motion
ellipsoids) showing the atom numbering scheme. Hydrogen atoms were
omitted for clarity.
2.4. The crystal structure of 7
Compound 7 (Fig. 3 and Table 2) crystallizes in the
monoclinic space group P21/n. The double bond
between the central carbon atoms of the bridging chain
is h2-coordinated to the titanium center at the open side
of the bent titanocene framework. The plane defined by
the double bond carbon atoms C(22) and C(23), and
titanium atom is approximately perpendicular to the
plane formed by centroids of the cyclopentadienyl rings
Cg(1) and Cg(2), and Ti, and very nearly bisects the
titanoceneꢁbtmse complexes [19a]. The crystal structure
/
of 8 did not reveal any extraordinary structural features
when compared with so far structurally characterized
titanoceneꢁbtmse complexes (see below).
/
Thermolysis of 8 at 150 8C for 10 h in m-xylene in a
sealed ampoule afforded a sky blue solid which was
1
analyzed by H- and 13C-NMR spectra as a mixture of
two isomeric doubly tucked-in compounds, sym- and
asym-ansa-[Ti{(h3:h4-C5Me2(CH2)2)(CH2)8(h5-
Cg(1)Ã
/
TiÃ
/
Cg(2) angle (Fig. 4). The cyclopentadienyl
C5Me4)}] (9) (Scheme 2). The third possible isomer in
which the pivotal atom of the ansa-linking chain are a
part of the h4-diene system was not detected. All NMR
resonances due to methyl groups of h5-cyclopentadienyl
and allyldiene ligands and their adjacent ipso-carbon
atoms as well as the signals of the exo-methylene groups
of both isomers present in the mixture are observed in
ca. 1:1 ratio. This indicates that a mixture of sym-9 and
asym-9 in ca. 1:2 molar ratio is obtained since a higher
symmetry of the sym isomer renders only one half of the
molecule symetrically independent. The products ratio
thus corresponds to a ratio statistically predicted con-
sidering all the cyclopentadienyl methyl groups equiva-
lent. The molecules of the both isomers are thermally
very robust, ionizing upon electron impact without
apparent fragmentation. The presence of the exo-
methylene groups is further indicated by an IR absorp-
tion band at 3032 cmꢃ1 and electronic absorption band
at 585 nm which are both found in regions typical for
doubly tucked-in titanocene complexes obtained from,
Table 2
a
˚
Selected bond lengths (A) and bond angles (8) for 7
Bond lengths
TiÃ
TiÃ
/
Cg(1)
2.101(2)
2.099(2)
1.429(6)
2.184(4)
1.510(6)
1.542(6)
/Cg(2)
C(22)Ã
TiÃC(22)
C(1)ÃC(19)
C(21)ÃC(22)
C(CH2)ÃC(CH2)
TiÃC(Cp)
C(Cp)Ã
C(Cp)Ã
TiÃ
C(10)Ã
C(23)Ã
/C(23)
/
/
/
/
1.505(6)ꢁ
2.380(4)ꢁ
1.413(6)ꢁ
1.489(6)ꢁ
2.192(4)
1.501(5)
1.534(5)
/
1.532(6)
2.447(4)
1.438(6)
1.518(6)
/
/
/
C(Cp)
/
/
Me
/
/
C(23)
/C(26)
/C(24)
Bond angles
Cg(1)Ã
TiÃC(23)Ã
C(21)Ã
/
TiÃ
/
Cg(2)
140.4(1)
70.7(2)
123.2(3)
40.2(2)
38.1(2)
71.2(2)
123.1(3)
/
/C(22)
/
C(22)ÃC(23)
/
b
f
C(22)Ã
TiÃC(22)Ã
C(22)Ã
/
TiÃ
/C(23)
/
/C(23)
e.g.
C5Me4R)2(h2-btmse)] (Rꢀ
[Ti(h5-C5Me5)2(h2-btmse)]
[4,19a],
benzyl, Ph, and 4-fluorophe-
[Ti(h5-
/
C(23)ÃC(24)
/
/
a
Cg(1) and Cg(2) are centroids of the C(1ꢁ
/
5) and C(10ꢁ14)
/
nyl) [19c], and [Ti{(h5-C5Me4SiMe2)2O}(h2-btmse)]
[19d].
cyclopentadienyl rings, respectively.
b
Dihedral angle between the least-squares cyclopentadienyl planes.

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
159
Fig. 4. A view of the molecular structure of 7 along the Cg(1)Ã
/Cg(2)
Fig. 5. The molecular structure of 8 (30% probability ellipsoids) with
the atom numbering scheme. Hydrogen atoms were omitted for clarity.
line.
rings are in a close-to-staggered conformation with the
dihedral angle (f) subtended by their least-squares
planes being 40.2(2)8. This value is close to the. values
found in ethene complexes [Ti(h5-C5Me5)2(h2-C2H4)] (f
40.6(4)8) [8] and [Ti{h5-C5Me4(SiMe3)}2(h2-C2H4)] (f
39.7(1)8) [9], and in another permethylated titanocene
[Ti(h5-C5Me5)(h2:h5-C22H35)] bearing an intramolecu-
larly coordinated double bond within a cyclooctene
annelated to one of the C5Me5 ligands [18a]. A smaller
f angle of 35.5(2)8 was observed in the silyl modified
analogue of 7, ansa-[Ti(II){h2:h5:h5-C5Me4SiMe2CH2-
Table 3
a
˚
Selected bond lengths (A) and bond angles (8) for 8
Bond lengths
TiÃ
TiÃ
TiÃ
/
Cg(1)
C(27)
C(Cp)
2.129(1)
2.120(3)
/
/
2.400(3)ꢁ
1.495(4)ꢁ
/
2.516(3)
1.510(4)
C(Cp)Ã
/
C(Me)
/
Si(1)Ã
Si(1)Ã
C(5)Ã
C(CH2)Ã
TiÃCg(2)
TiÃC(28)
C(Cp)ÃC(Cp)
C(27)ÃC(28)
/C(27)
1.873(3)
/C(Me)
1.868(4)ꢁ
1.522(4)
/
1.873(4)
1.541(5)
/C(6)
/C(CH2)
1.501(5)ꢁ
2.126(1)
2.119(2)
/
/
CHÄ/CHCH2SiMe2C5Me4}] (10) [17], most likely due to
/
a more rigid ansa-chain containing two SiMe2 groups
instead of four methylene groups in 7. The length of the
˚
coordinated double bond 1.429(6) A in 7 is slightly
/
1.400(4)ꢁ
1.298(4)
1.872(3)
/
1.428(4)
1.885(4)
/
Si(2)Ã
Si(2)Ã
/C(28)
˚
longer compared with that of 10 (1.411(6) A) and,
/C(Me)
1.861(4)ꢁ
1.519(4)
/
C(13)Ã
Bond angles
Cg(1)ÃTiÃCg(2)
C(28)ÃC(27)ÃTi
Si(1)ÃC(27)ÃC(28)
/C(14)
correspondingly, the TiÃ
/
C bond distances TiÃ
/
C(22)
C(23) (2.192(4) A) are shorter
˚
˚
(2.184(4) A) and TiÃ
/
˚
/
/
138.9(1)
72.1(2)
137.0(2)
40.4(2)
35.7(1)
72.2(2)
135.6(2)
compared with those of 10 (2.242(4) and 2.238(4) A)
[17]. These values indicate that the double bond in 7 is
coordinated more strongly than that in 10, apparently
due to a better adjustment of the double bond at the
bonding distance to the titanium center in the more
flexible C8 chain compared with the SiC4Si bridge.
/
/
/
/
b
f
C(27)Ã
C(27)Ã
Si(2)ÃC(28)Ã
/
TiÃ
C(28)Ã
C(27)
/C(28)
/
/Ti
/
/
a
Cg(1) and Cg(2) denote the centroids of the C(1ꢁ
/
5) and C(14ꢁ18)
/
cyclopentadienyl rings, respectively.
b
Dihedral angle subtended by the cyclopentadienyl least-squares
planes.
2.5. The crystal structure of 8
The molecule of 8 possesses no crystallographic
symmetry (Fig. 5 and Table 3). The arrangement of
the ansa-titanocene moiety is very similar to that in 6
[14a], adopting a near-to-staggered conformation of the
cyclopentadienyl rings and having the octan-1,8-diyl
chain attached to ring carbon atoms at the hinge
positions. However, a remarkable difference is observed
in the angle subtended by the least-squares planes of the
cyclopentadienyl rings (f). This angle is surprisingly
smaller than in 6 (40.4(2) vs. 43.9(1)8) and, conse-
quently, the methyl carbon atoms C(6) and C(13) are
declined from the least-squares planes of the cyclopen-
˚
tadienyl rings by 0.294(4) and 0.170(4) A, respectively.
Some steric hindrance between the btmse ligand and
methyl groups of the cyclopentadienyl ligands is indi-
cated by declinations of the methyl carbon atoms from
the least-squares planes of the cyclopentadienyl rings (cf.
perpendicular distance from the least-squares planes:
˚
C(20), 0.246(3); C(21), 0.213(3); and C(25), 0.175(4) A,
the methyl group close to the hinge position C(23) being
˚
declined by as much as 0.362(3) A due to its steric
interactions with the C(6) carbon atom of the bridging
chain. The planar geometry of the btmse ligand [C(27)Ã
/

160
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
˚
C(28) 1.298(4) A, CÃ
does not virtually differ from the geometry observed in
btmse
/
CÃ
/
Si angles 137.0(2) and 135.6(2)8]
ability of low-valent titanium complexes to isomerize
double bonds into their thermodynamically most con-
venient positions has been demonstrated many times
[25]. Much more interesting, however, is the formation
of 7 from bridge-saturated complex 6. In this case, the
reduction has to be carried in the absence of btmse
because the otherwise resulting h2-btmse complex 8 is
all other structurally characterized titanoceneꢁ
/
complexes: [Ti(h5-C5Me5)2(h2-btmse)] [23], [Ti(h5-
C5HMe4)2(h2-btmse)] [19a], ansa-[Ti{h5:h5-(C5Me4)2Si-
Me2}(h2-btmse) [24], [Ti{h5-C5Me4(4-C6H4F)}2(h2-
btmse)] [19c], [Ti(h5-C5Me4SiMe3)2(h2-btmse)] [9], and
ansa-[Ti{(h5-C5Me4SiMe2)2O}(h2-btmse)] [19d].
resistant towards magnesium similarly to all titanoceneꢁ
/
btmse complexes with highly methyl-substituted cyclo-
pentadienyl ligands [19]. The yield of 7 from 6 is lower
compared with that from 5 in accordance with a higher
complexity of the transformation of 6 into 7 which
requires an intermolecular hydrogen transfer from sp3
carbon atoms. Such reactions catalyzed by low-valent
titanium complexes were so far observed only for
unsaturated hydrocarbons and at much higher tempera-
tures [26]. The abstraction of hydrogen from the
saturated methylene chain under mild conditions (Mg,
60 8C) is apparently facilitated by frequent encounters
of titanium(II) with the flexible octane-1,8-diyl chain.
An assistance of magnesium in this process can be
considered because compound 7 was not formed when a
titanocene intermediate was formed during the thermo-
lysis of 8. The thermally induced dissociation of btmse
ligand from 8 as well as from [Ti(h5-C5Me4R)2(h2-
2.6. Conclusions
Compound 3 is apparently formed by reductive
removal of both chloride ligands followed by a subse-
quent intramolecular coordination of the pendant
double bond. The back-bonding interaction of the
double bond p-orbital and metal d2 system makes
compound 3 thermally robust (m.p. 111 8C) and reluc-
tant to fragmentate upon ionization in EIMS. This is in
accordance with the behaviour of an analogous
bis{(but-3-enyl)tetramethylcyclopentadienyl)}titanium-
(II) intermediate where the alkenyl chain is long enough
to allow the double bond to approach a low valent metal
center in the first step of a formal [2ꢂ
/
2ꢂ2] oxidative
/
cycloaddition involving p-electrons of both double
bonds and d2 electrons of titanium(II) which results in
the formation of symmetrical cyclopentadienyl ring-
tethered titanacyclopentane compound [14a]. At var-
iance, bis(1-methylallyl) titanocene intermediate with
shorter alkenyl groups gave an asymmetrical ring-
tethered titanacyclopentane [14a]. In the present case,
it appears likely that during the unexpected formation of
4 the transiently formed titanocene cannot stabilize by
forming a stable h2-alkene complex from the same
reason. A transient formation of an unstable intermedi-
ate with p-coordinated double bond should be, however,
anticipated as it would assist hydrogen abstraction from
the methyl group adjacent to the alkenyl substituent by
bringing it into a proximity of the electron-poor metal
center. Formally, the formation of 4 involves oxidative
btmse)] (RꢀMe, H, [19a], Ph, and 4-fluorophenyl
/
[19c]), and ansa-tetramethyldisiloxane [Ti{(h5-C5Me4-
SiMe2)2O}(h2-btmse)] [19d] complexes is accompanied
by hydrogen abstraction from two vicinal methyl groups
on one of the two fully substituted cyclopentadienyl
ligands to the leaving btmse. The asym isomer with the
vicinal methylene groups neighboring the group R or
the ansa-bridge is usually prevailing over the sym isomer
with the vicinal methylene groups at positions distant
from the substituent R or the ansa-bridge. Exceptional
behavior was observed only for [Ti{h5-C5Me4-
(CH2Ph)}2(h2-btmse)] complex where the isomer con-
taining vicinal benzylidene and methylene groups domi-
nated over the asym isomer with the benzyl group
untouched [19c]. Here, we have shown that the eight-
membered ansa-bridging chain does neither take part in
the hydrogen abstraction reaction nor even influences
addition of one methyl CÃ
center and an insertion of the double bond into the TiÃ
/
H bond across the Ti(II)
/
H bond in the only sterically allowed way. The presence
of bmtse during the reduction does not interfere with the
formation of 3 and 4 because in a competition between
btmse ligand and cyclopentadienyl ring-tethered double
bond for the Ti(II) center, the intramolecular process is
strongly preferred [14a,17]. Either of these p-donors,
however, prevents the formation of paramagnetic multi-
the product distribution; the distribution of CÃ
/
H
activated allyldiene complexes is statistical, reflecting
the number of the methyl groups on the cyclopentadie-
nyl rings.
nuclear titanocene hydrideꢁ/magnesium hydride com-
3. Experimental
plexes [22].
In view of the above results a smooth double bond
isomerization occurring in the unsaturated eight-mem-
bered carbon chain of 5 during the reduction to a
titanocene is well understandable. A feasible p-coordi-
nation of the symmetrically placed double bond in 7 is
apparent from its molecular structure (Fig. 3) and the
3.1. General comments
Syntheses of titanocene dichlorides 1 and 2 were
carried out under argon atmosphere and the products
were worked up and handled in air. The reductions and
all subsequent manipulations with solutions of the

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
161
products were performed on a vacuum line in all-sealed-
glass devices equipped with magnetically breakable
seals. A combined device equipped with a pair of quartz
cuvettes (10.0 and 1.0 mm, Hellma) and a quartz tube
recently described [14a]. A mixture of compounds
CH(CH2)5C5Me4}]
ansa-[TiCl2{h5:h5-C5Me4CH2CHÄ
/
(5) and ansa-[TiCl2{h5:h5-C5Me4(CH2)8C5Me4}] (6) in
molar ratio 2:5 as determined from NMR measurements
was obtained from the reaction of ring-tethered titana-
cyclopentane [Ti(IV)(h1:h1:h5:h5-C5Me4(CH2)2CH(Ti)-
(CH2)2CH(Ti)(CH2)2C5Me4] with HCl in hexane [14a].
Compounds 5 and 6 were separated from the above
obtained mixture by fractional crystallization from
toluene solution to give highly enriched compounds
was used for UVꢁnear IR and EPR measurements.
/
Crystals for EIMS measurements and melting point
determinations were placed into glass capillaries in a
glovebox Labmaster 130 (mBraun) under purified
nitrogen (concentrations of oxygen and water lower
than 2.0 ppm).
NMR spectra were recorded on a Varian UNITY
INOVA 400 spectrometer (1H, 399.95; 13C, 100.58
MHz) at 298 K. Chemical shifts (d ppm) are given
relative to residual protio signal of the solvent (dH 7.15
in benzene-d6) or to the solvent resonance (C6D6: dC
128.0). The assignment of NMR resonances is based on
2D COSY, DQF COSY, HMQC and HMBC experi-
ments. NMR samples of Ti(II) compounds were pre-
pared in evacuated all-glass devices from which the
(]95 mol.% in both cases) [15].
/
3.3. Preparation of titanocene dichlorides [TiCl2(h5-
C5Me5){h5-C5Me4(CH2CH2CHÄ
/
CH2)}] (1) and
[TiCl2(h5-C5Me5){h5-C5Me4CH(Me)CHÄ
/
CH2}] (2)
A slurry of [TiCl3(THF)3] was prepared in situ by
adding LiBu in hexanes (22.5 ml of 1.6 M, 36.0 mmol) to
TiCl4 (4.0 ml, 36.0 mmol) in THF (50 ml) followed by a
short reflux. In another flask, lithium cyclopentadienide
Li[C5Me5] was obtained by adding LiBu (14.5 ml of 2.5
M in hexanes, 36.25 mmol) to a solution of C5Me5H
(4.90 g, 36.0 mmol) in THF (300 ml). After stirring for 8
h, a white suspension of the cyclopentadienide was
mixed with the slurry of [TiCl3(THF)3] and the mixture
was refluxed for 1 h.
NMR tubes were sealed off by flame. UVꢁ
measurements were performed on a Varian Cary 17 D
spectrometer in the range 340ꢁ2000 nm. EIMS spectra
/near IR
/
were obtained on a VG-7070E double-focusing mass
spectrometer at 70 eV. Crystalline samples in sealed
capillaries were opened and inserted into the direct inlet
under argon. The spectra are represented by the peaks of
relative abundance higher than 6% and by important
peaks of lower intensity. IR spectra were recorded in an
air-protecting cuvette on a Nicolet Avatar FT IR
Meanwhile, lithium cyclopentadienide [Li{C5Me4-
CH2)}] was prepared by adding LiBu
(CH2CH2CHÄ
/
(12.8 ml of 2.5 M in hexanes, 32.0 mmol) to the solution
of a mixture of isomeric 5-(3-butenyl)-1,2,3,4-tetra-
methylcyclopentadienes (5.63 g, 32.0 mmol) in Et2O
(200 ml) followed by stirring for 8 h. The resulting white
slurry was mixed with the above reaction mixture
containing presumably [TiCl2(C5Me5)(THF)n] [28].
Diethyl ether was distilled off, and the residual mixture
was refluxed for 24 h. Then, the volume of the mixture
reduced to ca. 100 ml, and dry, powdery PbCl2 (5.0 g,
18.0 mmol) was added under argon [29]. A green
reaction mixture turned to red after stirring for 2 h at
40 8C. The reaction mixture was opened to air, all
volatiles were evaporated under vacuum, and the residue
was extracted by hexane. Crystalline product was
obtained by crystallization from a concentrated hexane
spectrometer in the range of 400ꢁ
4000 cmꢃ1. Samples
in KBr pellets were prepared in a glovebox Labmaster
130 (mBraun).
/
As low-valent titanium complexes are extremely
sensitive to air and moisture, classical elemental analyses
were not carried out. The EIMS samples of 3, 4, 7 and 9
were completely evaporated without changing the frag-
mentation pattern; this proves the uniformity of the
compounds.
3.2. Chemicals
Solvents THF, hexane, and toluene were dried by
refluxing over LiAlH4 and stored as solutions of dimeric
titanocene [(m-h5:h5-C10H8)(m-H)2{Ti(h5-C5H5)}2] [27].
Magnesium turnings (Aldrich, purum for Grignard
reactions) were first used in large excess for the
solution. Yield of brownꢁred crystalline product was 4.8
/
1
g. According to H- and 13C-NMR spectra the product
contained 1 and [TiCl2(h5-C5Me5)2] in 79:21 molar
ratio.
preparation of [Ti(h5-C5Me5)2(h2-Me3SiCÅ
/CSiMe3)]
[19a]. Then, the unreacted activated magnesium was
separated from the reaction mixture, washed thoroughly
with THF and stored in ampoules equipped with
breakable seals. Btmse (Fluka) was degassed, stored as
a solution of dimeric titanocene for 4 h, and finally
distributed into ampoules by distillation on a vacuum
line. Mixtures of isomers of 5-(3-butenyl)-1,2,3,4-tetra-
methylcyclopentadienes and 5-(1-methyl-2-propenyl)-
1,2,3,4-tetramethylcyclopentadienes were prepared as
Analytical data for 1: NMR (C6D6): dH 1.84 (s, 6H,
Me4C5), 1.85 (s, 15H, Me5C5), 1.90 (s, 6H, Me4C5),
1.93ꢁ
Me4C5CH2), 4.92 (ddt, 3JHH
1.2 Hz, 1H,
CH2), 4.98 (ddt, 3JHH
2JHH 4JHH
1.7 Hz, 1H, Ä
17.0, 10.1, JHH
(Me4C5), 13.0 (Me5C5), 13.1 (Me4C5), 27.8
(Me4C5CH2), 34.0 (Me4C5CH2CH2), 115.0 (ÄCH2),
/
2.01 (m, 2H, Me4C5CH2CH2), 2.62ꢁ
/
2.67 (m, 2H,
1.9, 4JHH
17.0,
ꢀ
/
10.2, 2JHH
ꢀ
/
ꢀ
/
Ä
/
ꢀ
/
3
:
/
:
/
/
CH2), 5.70 (ddt, JHH
ꢀ
/
3
ꢀ
/
6.7 Hz, 1 H, CH); dC 12.9
Ä
/
/

162
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
127.1, 131.4 (Me4C5 and Me5C5, Cipso; other resonances
not found due to possible overlap with solvent signal),
discarded and a repeated concentration of the mother
liquor (to ca. 2.5 ml) followed by cooling in a freezer
138.3 (Ä
/
CH). EIMS (170 8C, the spectrum was recorded
(ꢃ18 8C) gave a crop of crude 3 as somewhat waxy,
yellow crystalline material. Finally, this solid was twice
recrystallized by dissolution in hot hexane (60 8C) and
/
after the more volatile complex [TiCl2(h5-C5Me5)2] was
evaporated, peaks at m/z 318 and 155 disappeared): m/z
(relative abundance: 428 [M+ꢂ; 0.5], 393 ([Mꢃ
/
Cl]ꢂ; 9),
cooling to ꢃ5 8C to give 3 as a yellow crystalline solid.
/
295 (7), 293 ([Mꢃ
([Mꢃ
Cp?]ꢂ; 9), 218 ([Cp*TiCl]ꢂ; 28), 217 (23), 175
([Cp?]ꢂ; 25), 135 ([Cp*]ꢂ; 100), 134 (32), 133 (18), 120
(16), 119 (56), 107 (12), 105 (32), 91 (30) [Cp*ÄC5Me5,
Cp?ÄC5Me4(CH2CH2CHÄCH2)].
/
Cp*]ꢂ; 14), 258 ([Cp?TiCl]ꢂ; 12), 253
Yield: 0.27 g (29%). The yield is not optimized as no
attempt was made to recover more 3 from the mother
liquors. M.p. 111 8C. EIMS (120 8C): m/z (relative
abundance): 360 (12), 359 (32), 358 [Mꢂ+; 100), 357
(17), 356 (15), 355 (11), 354 (9), 353 (20), 218 (7), 181
(11), 180 (8), 179 (8), 178 (12), 177 (8). NMR (C6D6): dH
/
/
/
/
Complex 2 was prepared by exactly the same protocol
using a mixture of 5-(1-methyl-2-propenyl)-1,2,3,4-tetra-
methylcyclopentadienes (5.63 g, 32.0 mmol). The yield
0.69, 0.96, 1.35 (3ꢄ
C5Me4CH2CH2), 1.63 (s, 15H, C5Me5), 1.72 (dd, 1H,
JHH CH2), 2.43 (dd, 1 H, JHH 4.6, 9.8
5.2, 11.3 Hz, Ä
Hz, ÄCH2), 2.62 (s, 3H, C5Me4), 2.72 (t, 1H, JHH 9.9
Hz, CH Ä), 3.05 (dd, 1H, JHH 7.5, 12.9 Hz,
C5Me4CH2CH2), 3.51 (dd, 1H, JHH 8.3, 13.7 Hz,
C5Me4CH2), 4.34 (ddd, 1H, JHH,1 JHH,2 12.9,
JHH,3 7.6 Hz, C5Me4CH2); dC 9.6, 9.7, 11.0 (C5Me4);
11.6 (C5Me5), 15.1 (C5Me4), 25.2 (C5Me4CH2), 44.5
(C5Me4CH2CH2), 102.5 (ÄCH2), 115.1, 117.0, 118.1
),
/
s, 3 H, C5Me4); ca. 1.55 (m, 1H,
of a brownꢁ
/
red crystalline product, which was shown
ꢀ
/
/
ꢀ
/
by NMR spectroscopy to be a mixture of 2 and
[TiCl2(C5Me5)2] in 73: 27 molar ratio, was 4.3 g.
Analytical data for 2: NMR (C6D6): dC 1.21 (d,
/
ꢀ
/
/
ꢀ
/
ꢀ
/
3JHH
ꢀ
/
7.2 Hz, 3H, CHMe), 1.69, 1.74 (2ꢄ
/
s, 3H,
s, 3H,
1.9, 1.9 Hz,
2JHH
1.9
2JHH
17.4, 10.5, 5.0 Hz,
CH); dC 12.3, 12.8 (C5Me4); 13.1 (C5Me5), 13.6,
13.7 (C5Me4); 17.8 (CHMe), 36.8 (CHMe), 112.6
(ÄCH2), 125.1, 126.9 (C5Me4, Cipso); 128.4 (C5Me5),
129.1, 130.0, 135.4 (C5Me4, Cipso); 142.5 (ÄCH). EIMS
(170 8C, the spectrum was recorded as given above): m/z
(relative abundance): 428 [M+ꢂ; 1], 393 ([MꢃCl]ꢂ; 11),
297 (13), 296 (13), 295 (55), 294 (21), 293 ([Mꢃ
Cp*]ꢂ;
Cp?]ꢂ;
ꢀ
/
ꢀ
/
C5Me4); 1.87 (s, 15H, C5Me5), 2.04, 2.06 (2ꢄ
C5Me4); 3.86 (qddd, JHH
1H, CHMe), 4.92 (ddd, JHH
Hz, 1H, Ä
1.9 Hz, 1H, Ä
1H, Ä
/
ꢀ
/
3
3
Ä
/
7.2, 5.0, JHH
Ä
/
3
3
Ä
/
10.5, JHH
:
/
:
/
/
3
3
/
CH2), 4.98 (ddd, JHH
Ä
/
17.4, JHH
:
/
:
/
(C5Me4); 119.7 (C5Me5), 121.9 (C5Me4), 128.7 (CHÄ
/
/
CH2), 6.09 (ddd, 3JHH
Ä
/
141.5 (C5Me4). IR (KBr, cmꢃ1): 2955 (s), 2908 (vs),
2857 (s), 2811 (m), 1489 (m), 1442 (s, b), 1378 (vs), 1307
(w), 1094 (w), 1063 (w), 1022 (m), 792 (m), 747 (m), 722
/
/
(m), 630 (w), 613 (w), 586 (m), 436 (m). UVꢁNIR
/
/
(hexane, 23 8C): 970 nm.
/
3.5. Preparation of [Ti{h1:h1:h5-
C5Me3(CH2)(CH(Me)CH2CH2)}(h5-C5Me5)] (4)
/
78), 292 (9), 291 (7), 258 (9), 255 (12), 253 ([Mꢃ
/
16), 218 (8), 217 (8), 176 (11), 175 ([Cp?]ꢂ; 74), 160 (9),
The reduction and work-up was carried out as
described for 3 using 2ꢁ
[TiCl2(h5-C5Me5)2] mixture
145 (15), 136 (12), 135 ([Cp*]ꢂ; 100), 133 (16), 120 (9),
/
119 (29), 107 (8), 105 (22), 91 (12), 55 (11) [Cp*Ä
/C5Me5,
(molar ratio 73:27, 1.50 g, ca. 2.6 mmol of 2) to give
green crystalline 4 (0.21 g, ca. 23%; not-optimized). M.p.
135 8C. EIMS (120 8C): m/z relative abundance 360
(12), 359 33), 358 [Mꢂ+; 100], 357 (16), 356 (22), 355
(23), 354 (56), 353 (17), 352 (15), 341 (11), 340 (8), 339
Cp?ÄC5Me4(CH(Me)CHÄCH2)].
/
/
3.4. Preparation of [Ti(h5-C5Me5){h2:h5-
C5Me4(CH2CH2CHÄCH2)}] (3)
/
(11), 182 (8), 181 (8), 180 (9), 179 (6), 178 (13), 177 (13),
2
Crude compound
1
(containing 31 mol.% of
176 (9). NMR (C6D6): dH
3JHH
1.30 (d, JHH
2JHH 13.2, 3JHH
1.44 (ddd, 2JHH
1.45, 1.65 (2ꢄs, 3H, C5Me3), 1.65 (d, JHH
ꢃ
/
2.50 (ddd, JHH
ꢀ11.8,
/
[TiCl2(h5-C5Me5)2]; 1.50 g, ca. 2.6 mmol of 1) was
dissolved in THF (30 ml), btmse (0.9 ml, 4.0 mmol) was
added and the solution was poured onto activated
magnesium turnings (ca. 0.3 g, 12.5 mmol). The mixture
was kept at 60 8C until the color of the solution turned
greenish yellow (2 h). Then the remaining magnesium
was separated, the solution was evaporated under
vacuum and the residue was extracted repeatedly with
hexane. The extract was concentrated to crystallization
and then cooled in a refrigerator overnight whereupon
yellow prisms of 5 separated (identified by IR and EIMS
spectra, cf. [19a]). A further concentration of the mother
liquor followed by cooling gave another crop of crystal-
line material, which still contained 5 as indicated by IR
bands at 840 and 1240 cmꢃ1. Therefore, the solid was
ꢀ13.4, 7.0 Hz, 1 H, TiCH2), 1.07 (s, 3 H, C5Me3),
/
2
ꢀ
/
4.2 Hz, 1 H, C5Me3Ã
13.4, 11.2, 4.2 Hz, 1H, TiCH2CH2),
11.8, 3JHH
4.2, 1.9 Hz, 1H, TiCH2),
/
CH2), 1.33 (dddd,
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
3
/
ꢀ7.1 Hz,
/
2
3H, CHMe), 1.72 (s, 15H, C5Me5), 1.94 (d, JHH
ꢀ4.2
/
Hz, 1H, C5Me3Ã
/
CH2), 2.50 (dddd, 2JHH
7.1, 7.0, 1.9 Hz, 1 H, TiCH2CH2), 3.27 (ddq, JHH
ꢀ
/
13.2, 3JHH
ꢀ
/
3
ꢀ
/
11.2, 7.1, 7.1 Hz, 1H, CHMe); dC 10.0, 10.7, 11.3
(C5Me3); 11.6 (C5Me5), 21.3 (CHMe), 36.2 (CHMe),
47.1 (TiCH2CH2), 69.3 (TiCH2), 79.4 (C5Me3Ã
/CH2),
118.1 (C5Me5), 120.5, 121.5, 122.3, 129.7, 148.1
(C5Me3). IR (KBr, cmꢃ1): 3058 (w), 2973 (m), 2961
(s), 2949 (s), 2922 (vs), 2902 (vs), 2862 (s), 2815 (vs),
1487 (m), 1460 (vs), 1429 (s), 1377 (vs), 1362 (s), 1209

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
163
(w), 1161 (vw), 1073 (w), 1023 (s), 960 (w), 825 (s), 771
(w), 671 (m), 612 (w), 464 (m), 431 (w), 410 (s). UVꢁvis
(hexane, 23 8C): 610 nm.
(11), 390 (7), 389 (12), 217 (8), 202 (9), 201 (13), 200 (8),
197 (9), 182 (10), 181 (16), 180 (11), 179 (8), 178 (13), 177
/
(9), 170 ([btmse]ꢂ.; 8), 157 (11), 156 (19), 155 ([btmseꢃ
/
Me]ꢂ; 100), 135 (13), 133 (10), 119 (11), 91 (8), 73 (15).
1H-NMR (C6D6): d 0.02 (s, 9H, SiMe3), 1.26ꢁ
1.44 (br
1.89 (m,
3.6. Preparation of ansa-[Ti{h2:h5:h5-
/
C5Me4(CH2)3CHÄ
/
CH(CH2)3C5Me4}] (7)
m, 6H, 3ꢄ
/
CH2), 1.72 (s, 6H, C5Me4), 1.81ꢁ
/
2H, CH2), 2.08 (s, 6H, C5Me4). 13C{1H}-NMR (C6D6):
d 4.4 (SiMe3), 13.4, 14.2 (C5Me4); 22.2, 23.9, 25.4, 27.2
(CH2); 120.7 (2 C), 122.9 (1C), 125.2 (2 C) (C5Me4);
A mixture of 6 and 5 in molar ratio 5:2 [14a] (0.70 g,
1.48 mmol) and activated magnesium (0.3 g, 12.3 mmol)
were evacuated in an ampoule and THF (30 ml) were
distilled in on a vacuum line under cooling with liquid
nitrogen. The ampoule was sealed off, warmed to 60 8C,
and stirred until the color of the solution turned to dark
yellow (5 h). The ampoule was opened on a vacuum line,
THF was evaporated, and the residue extracted with
hexane (30 ml). The solution was concentrated, and
248.3 (h2-CÅ
/
C). 29Si-NMR (C6D6): d ꢃ
17.9 (SiMe3).
/
IR (KBr, cmꢃ1): 2938 (s), 2887 (vs), 2860 (sh), 2840 (sh),
1635 (w), 1594 (m), 1558 (s), 1450 (m, b), 1375 (m), 1348
(w), 1291 (w), 1241 (vs), 1070 (w, b), 1017 (m), 840 (vs,
b), 750 (s), 679 (m), 655 (m), 618 (w), 564 (vw), 448 (s),
430 (m). UVꢁ
/
NIR (hexane, 22 8C): 395(sh)ꢁ910 nm.
/
cooled to ꢃ18 8C overnight. Yellow crystals were
/
separated from the mother liquor and recrystallized
from hexane. Yield of yellow prisms was 0.44 g (74%).
Analytical data for 7: M.p. 150 8C. EIMS (150 8C):
m/z (relative abundance) 401 (14), 400 (39), 399 (44),
398 [M+ꢂ; 100], 397 (33), 396 (55), 395 (25), 394 (21),
393 (30), 392 (12), 391 (17), 390 (7), 389 (11), 192 (10),
191 (9), 190 (8), 182 (14), 181 (19), 180 (14), 179 (9), 178
(20), 177 (12), 176 (9), 133 (72), 122 (26), 121 (29), 120
(27), 119 (100), 117 (29), 119 (8), 41 (15). IR (KBr,
cmꢃ1): 3008 (m), 2956 (sh), 2907 (vs, b), 2856 (s, b),
2810 (s), 1486 (m), 1438 (vs), 1376 (s), 1356 (w), 1324
(w), 1266 (w), 1179 (m), 1100 (w), 1084 (w), 1068 (w),
1022 (m), 982 (w), 930 (w), 876 (w), 860 (m), 817 (w), 789
(w), 714 (m), 615 (vw), 583 (m), 538 (w), 522 (vw), 502
(vw), 430 (m), 409 (s).
3.8. Thermolysis of 8 to give 9
A solution of complex 8 (1.3 g, 2.3 mmol) in m-xylene
(30 ml) in an evacuated ampoules was heated to 150 8C
for 10 h. The conversion of 8 to 9 was indicated by a
change of the solution colour from yellow to sky blue.
m-Xylene and other volatiles were distilled off in
vacuum, and the residue was extracted with hexane
(5 ml). Compound 9 was crystallized from the concen-
trated hexane solution by cooling to give a blue finely
polycrystalline material. Yield 0.80 g (87%).
M.p. 130 8C. 1H-NMR signals due to the ansa chains
are grouped between 0.45 and 2.35 ppm. Their extensive
overlapping prevented any detailed analysis of the NMR
spectra, thus only sharp signals of the exo-methylene
and methyl groups that could be unequivocally identi-
fied are given here. 1H-NMR (C6D6): d 1.09, 1.31, 1.37,
Compound 7 was analogously prepared from 0.40 g
of 6 containing 5% of 5 [14a] in the yield of 0.18 g (54%),
and from 0.20 g of 5 containing 5% of 6 [15] in yield of
0.15 g (88%).
1.41, 1.55, 1.59, 2.21, 2.21, 2.37 (9ꢄ
/
s, 3 H, Me4C5 and
4.2 Hz, ÄCH2 A);
CH2 B); 0.87, 1.29
CH2 C). 13C{1H}-NMR
2
Me2C5); 0.78, 0.88 (2ꢄ
/
d, JHH
ꢀ
/
/
2
d, JHH
3.7. Preparation of ansa-[Ti{h5:h5-
0.85, 0.89 (2ꢄ
/
ꢀ
/
4.6 Hz, Ä
/
2
d, JHH
C5Me4(CH2)8C5Me4}(h2-Me3SiCÅ
/
CSiMe3)] (8)
(2ꢄ
/
ꢀ/4.9 Hz,
Ä
/
(C6D6): d 10.2, 11.0, 11.3, 11.4, 11.4, 11.8, 13.9, 14.0,
14.7 (Me4C5 and Me2C5); 24.3, 24.6, 26.3, 26.4, 26.5,
26.9, 28.5, 28.5 (ansa-(CH2)8 major); 24.0, 25.0, 25.1,
25.5, 25.7, 27.8, 28.3, 30.3 (ansa-(CH2)8 minor); 67.5
Compound 1 (1.4 g, 2.96 mmol) and activated
magnesium (0.6 g, 24.6 mmol) were evacuated in an
ampoule, and THF (50 ml) was distilled in on a vacuum
line under cooling by liquid nitrogen. The ampoule was
sealed off, and btmse (1.8 ml, 8.0 mmol) was added from
an attached ampoule. The resulting mixture was heated
to 60 8C with stirring until the colour of the mixture
turned clear yellow (1 h). The ampoule was opened on a
vacuum line, THF and excess btmse were evaporated,
and the residue was extracted by hexane. The yellow
solution was concentrated and the product crystallized
(Ä
/
CH2 C), 68.6 (Ä
/
CH2 B), 70.6 (Ä
/
CH2 A), 115.4,
118.8, 118.9, 121.0, 121.4, 121.6, 122.4, 122.5 (2 C),
125.8, 128.5, 134.3, 139.1, 144.1, 144.4, 144.9 (Me4C5
and Me2C5). EIMS (90 8C): m/z (relative abundance)
400 (16), 399 (44), 398 [Mꢂ+; 100], 397 (17), 396 (20),
395 (5), 394 (7), 393 (5), 192 (6), 182 (7), 181 (8), 180 (6),
178 (8), 177 (6), 91 (6). IR (KBr, cmꢃ1): 3032 (m), 2932
(s, b), 2903 (vs, vb), 2840 (s), 1626 (vw), 1480 (sh), 1465
(sh), 1440 (vs), 1377 (s), 1341 (m), 1301 (vw), 1287 (w),
1260 (w), 1076 (m, b), 1023 (s), 882 (vw), 867 (vw), 828
(s), 815 (sh), 805 (sh), 742 (w), 733 (m), 613 (vw), 605
from a solution at ꢃ
1.44 g (85%).
M.p. 140 8C. EIMS (150 8C): m/z (relative abun-
dance) 401 (15), 400 ([Mꢃ
btmse]ꢂ, 40), 399 (20), 398
(60), 397 (22), 396 (30), 395 (19), 394 (17), 393 (28), 392
/
18 8C. Yield of yellow crystals of 8:
/
(w), 579 (m), 561 (w), 464 (sh), 434 (m). UVꢁ
(hexane): 585 nm.
/vis

164
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
3.9. X-ray crystallography
multiple twinning where diffraction contributions of
the other (minor) parts could not be substracted from
the major one. Although this results in rather high R-
values and large residual electron density peaks in areas
close to the heaviest atom in the structure, the chemical
picture is unambiguous and the metric parameters are
reliable.
A dark green prism of complex 4 and yellow prismatic
crystals of 7 and 8 were inserted into Lindemann glass
capillaries in a glove box and sealed by a wax. All
diffraction data were collected on a Nonius KappaCCD
diffractometer. The structures were solved by direct
methods (SIR-92, [30]) and refined by full-matrix least-
squares on F2
(SHELXL-97 [31]). Relevant crystallo-
graphic data are given in Table 4; particular details
about the structure solution follow.
3.9.3. Compound 8
The non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms of the methyl groups were
included in idealized position (riding model) while all
other hydrogen atoms were identified on difference
electron density maps and refined with isotropic thermal
motion parameters.
3.9.1. Compound 4
The non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms residing on C(6), C(20), C(21),
and C(22) were identified on difference electron density
maps and refined with isotropic thermal motion para-
meters while methyl hydrogen atoms were included in
calculated positions.
4. Supplementary material
Crystallographic data, excluding structure factors,
have been deposited at the Cambridge Crystallographic
Data Centre (4: CCDC-192553, 7: CCDC-189754, 8:
CCDC-189755). Copies of the data can be obtained free
of charge upon application to The Director, CCDC 12
3.9.2. Compound 7
All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms at the h2-coordinated double bond
(H(22) and H(23)) were found on a difference electron
density maps and isotropically refined. All other hydro-
gen atoms were included in geometrically optimized
positions. The crystals of complex 7 suffered from
Union Road, Cambridge CB2 1EZ, UK (Fax: ꢂ44-
/
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Table 4
Crystallographic data, data collection and structure refinement data for 4, 7 and 8
Compound
4
7
8
Chemical formula
Molecular weight
Crystal system
Space group
C23H34Ti
358.40
C26H38Ti
398.46
C34H58Si2Ti
570.88
Monoclinic
P21/n (No. 14)
293
Monoclinic
P21/n (No. 14)
150
Monoclinic
P21/n (No. 14)
293
T (K)
˚
a (A)
˚
9.4100(2)
16.9170(3)
12.4430(3)
96.1920(13)
1969.23(7)
4
9.5550(3)
14.1280(5)
15.6510(5)
91.488(2)
2112.1(1)
4
17.576(1)
9.6580(7)
21.042(2)
107.548(4)
3405.6(5)
4
b (A)
˚
c (A)
b (8)
3
V (A )
˚
Z
Crystal size (mm3)
0.30ꢄ
/
0.35ꢄ
/
0.50
0.30ꢄ
/
0.35ꢄ
/0.50
0.17ꢄ/0.37ꢄ0.45
/
Dcalc (g cmꢃ3
)
1.209
0.436
776
1.253
0.413
864
1.113
0.341
1248
m (Moꢁ
F(000)
u Range (8)
/
Ka) (mmꢃ1
)
3.1ꢁ/27.5
3.0ꢁ
/
26.0
3.2ꢁ25.1
/
Diffractions collected
Independent diffractions
13 209
4491
3699
254
12 429
4152
3179
260
12 332
5740
4336
412
a
Diffraction observed
Number of parameters
b
R, wR (observed diffractions)
b
0.0397, 0.0961
0.0537, 0.1035
1.02
0.0893, 0.235
0.112, 0.246
1.69
0.0484, 0.110
0.0727, 0.122
1.05
R, wR (all data)
c
S
ꢃ3
˚
r (e A
)
0.32, ꢃ
/0.293
2.73, ꢃ
/
0.85
0.22, ꢃ0.23
/
a
I ꢂ
R(F)ꢀ
/
2s(I).
/
ajjFojꢃ
/
jFcjj/ajFoj, wR(F2)ꢀ
/
[a(w(F2oꢃ
/
F2c)2)/(aw(F2o)2)]1/2
.
b
c
Sꢀ
/
[a(w(F2oꢃ
/
Fc2)2)/(Ndiffrs Nparams)]1/2
ꢃ .
/

M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ
/166
165
Chem. 583 (1999) 11;
(c) J. Zema´nek, L. Frohlichova´, P. .Sindela´rˇ, P. Steˇpnicˇka, I.
Acknowledgements
ˇ
ˇ
¨
C´ısarˇova´, V. Varga, M. Hora´cˇek, K. Mach, Collect. Czech.
Chem. Commun. 66 (2001) 1359.
This work was financially supported by the Grant
Agency of Academy of Sciences of the Czech Republic
(project no. A4040004) and Grant Agency of the Czech
Republic (grant Nos. 203/02/0436, 203/99/M037). It is
also a part of a long-term research plan of the Faculty of
Sciences, Charles University.
[13] (a) N. Suzuki, H. Asami, T. Nakamura, T. Huhn, A. Fukuoka,
M. Ichikawa, M. Saburi, Y. Wakatsuki, Chem. Lett. (1999) 341;
(b) H. Zhu, G.-X. Jin, N. Hu, J. Organomet. Chem. 655 (2002)
167;
(c) H.G. Alt, J. Chem. Soc. Dalton Trans. (1999) 1703;
(d) H.G. Alt, M. Jung, J. Organomet. Chem. 580 (1999) 1;
(e) H.G. Alt, A. Reb, W. Milius, A. Weis, J. Organomet.Chem.
628 (2001) 169.
ˇ
[14] (a) M. Hora´cˇek, P. .Steˇpnicˇka, R. Gyepes, I. C´ısarˇova´, I.
Tisˇlerova´, J. Zema´nek, J. Kubisˇta, K. Mach, Chem. Eur. J. 6
References
(2000) 2397;
(b) T.H. Waren, G. Erker, R. Frohlich, B. Wibbeling, Organo-
¨
[1] (a) N.J. Long, Metallocenes, Blackwell Science, Oxford, UK,
1998;
metallics 19 (2000) 127.
ˇ
[15] M. Hora´cˇek, P. .Steˇpnicˇka, K. Fejfarova´, R. Gyepes, I. C´ısarˇova´,
(b) R. Beckhaus, in: A. Togni, R.L. Halterman (Eds.), Metallo-
cenes, vol. 1 (Chapter 4), Wiley-VCH, Weinheim, Germany, 1998,
p. 153.
J. Kubisˇta, K. Mach, J. Organomet. Chem. 642 (2002) 148.
[16] M. Bochmann, in: E.W. Abel, F.G.A. Stone, G. Wilkinson, M.F.
Lappert (Eds.), Comprehensive Organometallic Chemistry II, vol.
[2] (a) J.E. Bercaw, H.H. Brintzinger, J. Am. Chem. Soc. 93 (1971)
2045;
4 (Chapter 5), Elsevier, 1995, pp. 314ꢁ320.
/
ˇ
[17] L. Lukesˇova´, P. .Steˇpnicˇka, R. Gyepes, I. C´ısarˇova´, M. Hora´cˇek,
J. Kubisˇta, K. Mach, Organometallics 21 (2002) 2639.
[18] (a) P.-M. Pellny, V.V. Burlakov, W. Baumann, A. Spannenberg,
(b) J.E. Bercaw, R.H. Marvich, L.G. Bell, H.H. Brintzinger, J.
Am. Chem. Soc. 94 (1972) 1219;
(c) J.E. Bercaw, J. Am. Chem. Soc. 96 (1974) 5087.
[3] T. Vondra´k, K. Mach, V. Varga, A. Terpstra, J. Organomet.
Chem. 425 (1992) 27.
ˇ
M. Hora´cˇek, P. .Steˇpnicˇka, K. Mach, U. Rosenthal, Organome-
tallics 19 (2000) 2816;
(b) M. Hora´cˇek, P. .Steˇpnicˇka, R. Gyepes, I. C´ısarˇova´, M.
ˇ
[4] (a) J.W. Pattiasina, C.E. Hissink, J.L. de Boer, A. Meetsma, J.H.
Teuben, A.L. Spek, J. Am. Chem. Soc. 107 (1985) 7758;
(b) K. Mach, V. Varga, V. Hanusˇ, P. Sedmera, J. Organomet.
Chem. 415 (1991) 87.
Pola´sˇek, K. Mach, P.-M. Pellny, V.V. Burlakov, W. Baumann,
A. Spannenberg, U. Rosenthal, J. Am. Chem. Soc. 121 (1999)
10638.
[19] (a) V. Varga, K. Mach, M. Pola´sˇek, P. Sedmera, J. Hiller, U.
Thewalt, S.I. Troyanov, J. Organomet. Chem. 506 (1996) 241;
[5] J.M. Fischer, W.E. Piers, V.G. Young, Organometallics 15 (1996)
2410.
ˇ
(b) P. .Steˇpnicˇka, R. Gyepes, I. C´ısarˇova´, M. Hora´cˇek, J. Kubisˇta,
K. Mach, Organometallics 18 (1999) 4869;
ˇ
(c) V. Kupfer, U. Thewalt, I. Tisˇlerova´, P. .Steˇpnicˇka, R. Gyepes,
[6] (a) U. Rosenthal, V.V. Burlakov, in: I. Marek (Ed.), Titanium
and Zirconium in Organic Synthesis (Chapter 10), Wiley-VCH,
Weinheim, 2002, p. 355;
J. Kubisˇta, M. Hora´cˇek, K. Mach, J. Organomet. Chem. 620
(2001) 39;
ˇ
(d) M. Hora´cˇek, P. .Steˇpnicˇka, J. Kubisˇta, R. Gyepes, I. C´ısarˇova´,
(b) U. Rosenthal, P.-M. Pellny, F.G. Kirchbauer, V.V. Burlakov,
Acc. Chem. Res. 33 (2000) 119 (and references therein).
[7] (a) P.-M. Pellny, F.G. Kirchbauer, V.V. Burlakov, W. Baumann,
A. Spannenberg, U. Rosenthal, J. Am. Chem. Soc. 121 (1999)
8313;
L. Petrusova´, K. Mach, J. Organomet. Chem. 658 (2002) 235.
[20] G.A. Luinstra, J. Vogelzang, J.H. Teuben, Organometallics 11
(1992) 2273.
(b) P.-M. Pellny, F.G. Kirchbauer, V.V. Burlakov, W. Baumann,
A. Spannenberg, U. Rosenthal, Chem. Eur. J. 6 (2001) 81 (and
references cited therein).
[21] J.W. Lauher, R. Hoffmann, J. Am. Chem. Soc. 98 (1976) 1729.
ˇ
[22] (a) V. Varga, L. Petrusova´, J. .Cejka, K. Mach, J. Organomet.
Chem. 532 (1997) 251;
(b) M. Hora´cˇek, J. Hiller, U. Thewalt, M. Pola´sˇek, K. Mach,
Organometallics 16 (1997) 4185;
[8] S.A. Cohen, P.R. Auburn, J.E. Bercaw, J. Am. Chem. Soc. 105
(1983) 1136.
ˇ
[9] M. Hora´cˇek, V. Kupfer, U. Thewalt, P. .Steˇpnicˇka, M. Pola´sˇek,
(c) R. Gyepes, K. Mach, I. C´ısarˇova´, J. Loub, J. Hiller, P.
ˇ
.Sindela´rˇ, J. Organomet. Chem. 497 (1995) 33;
K. Mach, Organometallics 18 (1999) 3572.
[10] (a) J. Okuda, K.E. du Plooy, P.J. Toscano, J. Organomet. Chem.
495 (1995) 195;
(d) S.I. Troyanov, V. Varga, K. Mach, J. Organomet. Chem. 461
(1993) 85;
(b) R.E.V.H. Spence, W.E. Piers, Organometallics 14 (1995) 4617;
(c) W.E. Piers, Chem. Eur. J. 4 (1998) 13;
(d) B. Temme, G. Erker, J. Karl, H. Luftmann, R. Frohlich, S.
¨
(e) S.I. Troyanov, V. Varga, K. Mach, J. Chem. Soc. Chem.
Commun. (1993) 1174.
[23] V.V. Burlakov, A.V. Polyakov, A.I. Yanovsky, Y.T. Struchkov,
Kotila, Angew. Chem. Int. Ed. Engl. 34 (1995) 1755;
(e) B. Temme, J. Karl, G. Erker, Chem. Eur. J. 2 (1996) 919;
V.B. Shur, M.E. Vol’pin, U. Rosenthal, H. Gorls, J. Organomet.
¨
Chem. 476 (1994) 197.
(f) J. Karl, G. Erker, R. Frohlich, J. Am. Chem. Soc. 119 (1997)
¨
11165;
[24] V. Varga, J. Hiller, R. Gyepes, M. Pola´sˇek, P. Sedmera, U.
Thewalt, K. Mach, J. Organomet. Chem. 538 (1997) 63.
[25] (a) M. Bochmann, in: E.W. Abel, F.G.A. Stone, G. Wilkinson,
M.F. Lappert (Eds.), Comprehensive Organometallic Chemistry
(g) A.H. Cowley, G.S. Hair, B.G. McBurnett, R.A. Jones, Chem.
Commun. (1999) 437.
[11] (a) H. Schumann, D.F. Karasiak, S.H. Muhle, R.L. Haltermann,
¨
II, vol. 4 (Chapter 4), Elsevier, 1995, pp. 263ꢁ264;
(b) Y. Qian, G. Li, X. Zheng, Y.Z. Zhuang, J. Mol. Catal. 78
(1993) L31;
/
W. Kaminsky, U. Weingarten, J. Organomet. Chem. 579 (1999)
356;
(b) H. Schumann, D.F. Karasiak, S.H. Muhle, W. Kaminsky, U.
¨
Weingarten, J. Organomet. Chem. 636 (2001) 31.
[12] (a) T.E. Ready, J.C.W. Chien, M.D. Rausch, J. Organomet.
Chem. 519 (1996) 21;
(c) K. Mach, F. Turecˇek, H. Antropiusova´, L. Petrusova´, V.
Hanusˇ, Synthesis (1982) 53;
(d) K. Mach, H. Antropiusova´, V. Hanusˇ, F. Turecek, J.
Organomet. Chem. 269 (1984) 39.
(b) T.E. Ready, J.C.W. Chien, M.D. Rausch, J. Organomet.

166
M. Hora´cˇek et al. / Journal of Organometallic Chemistry 667 (2003) 154ꢁ166
/
[26] K. Mach, L. Petrusova´, H. Antropiusova´, V. Hanusˇ, F. Turecˇek,
P. Sedmera, Collect. Czech. Chem. Commun. 48 (1983) 2924.
[27] H. Antropiusova´, A. Dosedlova´, V. Hanusˇ, K. Mach, Transition
Met. Chem. (London) 6 (1981) 90.
[30] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C.
Giacovazzo, A. Guagliardi, G. Polidori, J. Appl. Crystallogr. 27
(1994) 435.
[31] G.M. Sheldrick, SHELXL-97. Program for Crystal Structure
[28] G. Schmid, U. Thewalt, P. Sedmera, V. Hanusˇ, K. Mach, Collect.
Czech. Chem. Commun. 63 (1998) 636 (and references therein).
[29] G.A. Luinstra, J.H. Teuben, J. Chem. Soc. Chem. Commun.
(1990) 1470.
Refinement from Diffraction Data, University of Gottingen,
¨
Gottingen, 1997.
¨