Titanium and zirconium complexes containing the new 2,3-dimethyl-1,4-diphenylcyclopentadienyl ligand. Synthesis, characterization and polymerization behavior

Article abstract of DOI:10.1016/j.jorganchem.2004.01.037

An easy and inexpensive three-step synthesis of new 2,3-dimethyl-1,4-diphenylcyclopentadiene (3) ligand and the titanium and zirconium homometallocene dichlorides [TiCl₂ (η⁵-C₅H-2,3-Me₂-1, 4-Ph₂)

Full text of DOI:10.1016/j.jorganchem.2004.01.037

Journal of Organometallic Chemistry 689 (2004) 1623–1630
www.elsevier.com/locate/jorganchem
Titanium and zirconium complexes containing the new
2,3-dimethyl-1,4-diphenylcyclopentadienyl ligand. Synthesis,
characterization and polymerization behavior
a
Jirı Pinkas , Michal Horacek , Jirı Kubista , Robert Gyepes , Ivana Cısarova ,
a
a
b
b
ꢀꢁ
ꢁꢀ
ꢀꢁ
ꢀ
Nadine Pirio , Philippe Meunier , Karel Mach
ꢁ
ꢁ ꢀ ꢁ
c
c
a,
*
a
J. Heyrovskꢁy Institute of Physical Chemistry, Academy of Sciences of the Czech Republic,
Dolejꢀskova 3, 182 23 Prague 8, Czech Republic
Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
b
c
Laboratoire de Synthꢂese et Electrosynthꢂese Organomꢁetalliques Associꢁe au CNRS (UMR 5188), Facultꢁe des Sciences,
Universitꢁe de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France
Received 28 October 2003; accepted 15 January 2004
Abstract
An easy and inexpensive three-step synthesis of new 2,3-dimethyl-1,4-diphenylcyclopentadiene (3) ligand and the titanium and
zirconium homometallocene dichlorides [TiCl2(g5-C5H-2,3-Me2-1,4-Ph2)2] (4), [ZrCl2(g5-C5H-2,3-Me2-1,4-Ph2)2] (5), and the
mixed ligand zirconium complex [ZrCl2(g5-C5H-2,3-Me2-1,4-Ph2)(g5-C5H5)] (6) prepared thereof are described. The polymeriza-
tion of ethene using 4–6/MAO catalysts revealed that zirconocene complexes 5 and 6 displayed moderate and high activity, re-
spectively, whereas the titanium catalyst 4/MAO was inactive. The crystal structures of 4 and 5 were determined by X-ray
crystallography.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Titanocene; Zirconocene; 2,3-Dimethyl-1,4-diphenylcyclopentadiene; Polymerization; Ethene; Crystal structure
1. Introduction
olefin copolymerizations [3]. Particularly, the substitu-
tion of cyclopentadienyl rings in zirconocene dichlorides
by phenyl group(s) modified the catalytic behavior of
polymerization catalysts derived thereof for polymeri-
zation of ethene and other 1-alkenes [4–8]. The intro-
duction of phenyl group in 2-position of indenyl rings in
bis(indenyl)zirconium dichloride/MAO catalyst slowed
down mutual rotation of the ligands to give transient
racemic and meso rotamers, which consequently pro-
duced isotactic and atactic polypropylene blocs [9]. The
highly phenylated cyclopentadienyl zirconocene dichlo-
ride [ZrCl2{(g5-C5Ph5)(g5-C5H5)}] has been used for
[4 + 2] cycloaddition of methyl- and ethylmethacrylate to
cyclopentadiene [10].
The discovery of methylalumoxane (MAO) in 1980
by Kaminsky and co-workers [1] led to a new applica-
tion of Group 4 metallocenes as highly efficient catalysts
for ethene polymerization. Simple zirconocene dichlo-
ride which showed the highest polymerization activity
among early transition metallocene dichlorides [2] was
soon modified by various substituents on the cyclopen-
tadienyl rings strongly influencing the steric and elec-
tronic property of the catalytic center and its catalytic
behavior, particularly in polymerization of propene and
In this paper, we report the synthesis of the new 2,3-
dimethyl-1,4-diphenylcyclopentadienyl ligand, its ti-
tanocene and zirconocene complexes, and their catalytic
activity in polymerization of ethene.
* Corresponding author. Tel.: +420-2-8658-5367/6605-3735; fax:
+420-2-8658-2307.
E-mail address: mach@jh-inst.cas.cz (K. Mach).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.01.037

1624
J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
2. Results and discussion
2.1. Synthesis of the ligand precursor
tetramethylcyclopentadiene (d 2.60 ppm) [16], appar-
ently resulting from an electron-withdrawing effect of
the two phenyl groups.
The synthesis of 2,3-dimethyl-1,4-diphenylcyclo-
penta-1,3-diene (3) (Scheme 1) was based on a modifi-
cation of the method used for the preparation of
tetramethylcyclopentenone [11]. 2-Butyl cinnamate (1)
was prepared by acid-catalyzed esterification of cin-
namic acid with 2-butanol in nearly quantitative yield
[12]. The conversion of 1 to a mixture of cyclopente-
nones (2 and 20) was accomplished both by polyphos-
phoric acid (PPA) [13] or by a solution of P2O5 in
methanesulfonic acid [14]. The method using PPA is
more convenient because it produces a purer product,
and the 1/PPA ratio (w/w) can be increased to 1:5
against the reported ratio 1:8 [13] or 1:45 [15] without
any significant change in yield. Moreover, the hydrolysis
of PPA at elevated temperature (40–50 °C) facilitates the
product isolation. In both cases, 1H NMR and 13C
NMR analysis indicated that a mixture of 2,3-dimethyl-
4-phenylcyclopent-2-enone (2) (ca. 95%) and 4,5-di-
methyl-3-phenylcyclopent-2-enone (20) (ca. 5%) was
obtained. The mixture of cyclopentenones (2 + 20) was
reacted with an excess of phenylmagnesium bromide,
the product was hydrolyzed to give the corresponding
alcohol, and its iodine-catalyzed dehydration produced
2,3-dimethyl-1,4-diphenylcyclopentadiene (3) as the
only isomer in overall yield of 25%. The 1H NMR
spectrum of 3 showed a down-field shift of the signal for
methylene protons (d 3.47 ppm) compared to that in
2.2. Synthesis of metallocene dichlorides 4, 5, and 6
Syntheses of the metallocene dichlorides were carried
out using standard methods (Scheme 2). Corresponding
anions were obtained by conventional reaction of 2,3-
dimethyl-1,4-diphenylcyclopenta-1,3-diene (3) with one
equivalent of n-butyllithium in diethyl ether at 0 °C. A
treatment of the ligand anion with 0.5 equivalent of
TiCl3(THF)3 in tetrahydrofuran (THF) gave, after oxi-
dation by CCl4 and recrystallization from a toluene/
hexane mixture bis(g5-2,3-dimethyl-1,4-diphenylcyclo-
pentadienyl)dichlorotitanium (4) as deep red crystals in
76% yield. Similarly, the reaction of two equivalents of
the above lithium salt with ZrCl4 in toluene gave yellow
crystalline bis(g5-2,3-dimethyl-1,4-diphenylcyclopenta-
dienyl)dichlorozirconium (5) in yield of 62%. The
zirconium complex with mixed ligands (g5-2,3-dimethyl-
1,4-diphenylcyclopentadienyl)(g5-cyclopentadienyl)di-
chlorozirconium (6) was prepared by reacting lithium
salt of 3 with [CpZrCl3(DME)]. All the complexes 4–6 in
the solid state were air and moisture stable.
The identity of compounds was deduced from their
1H and 13C NMR spectra, IR and EI-MS spectra, and
elemental analyses. Crystal structures of 4 and 5 were
determined by X-ray diffraction analysis (see below).
The NMR and IR spectra mainly proved the presence of
g5-bonded ligand anions of 3, and NMR spectra did not
Scheme 1.
Scheme 2.

J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
1625
indicate signs of restricted rotation of the cyclopenta-
dienyl ligands and phenyl substituents at room temper-
ature. The mass spectra proved the expected molecular
compositions and revealed considerable differences in
fragmentation patterns of the complexes. While in the
mass spectrum of 5 the [M–C5Me2Ph2H]þ ion was the
base peak, in the spectrum of 4 the [M–C5Me2Ph2H]þ
fragment had a relative abundance of only (16%) and
[C5Me2Ph2H]þ was the base peak. This fragmentation
behavior reflects a higher electropositivity of zirconium
compared to titanium and a larger steric congestion in 4
compared to 5. In EI-MS spectrum of 6 the [M–C5H5]þ
ion was more abundant than the [M–CpMe2Ph2H]þ ion.
phous complexes crystallize in the monoclinic P21=c
space group with two crystallographically independent
molecules (denoted 4a and 4b for compound 4, and 5a
(Fig. 1) and 5b for compound 5) in the unit cell, which
differentiate mainly in orientations of phenyl groups.
Compounds 4 and 5 differ mainly in the lengths of M–
Cg (Cg-centroid of the cyclopentadienyl ring) and M–Cl
bonds, the difference being caused mainly by different
covalent radii of both the metals. This difference has,
however, no effect on dihedral angles between least-
squares planes of cyclopentadienyl rings (/) which
amount to 54.61(10)° and 55.57(12)° for 4, and 54.34(6)°
and 56.10(7)° for 5. The Cg–M–Cg angles for 4a
(133.70(5)°), 4b (130.00(5)°), 5a (132.11(3)°), and 5b
(130.84(3)°) are in the range typical for octamethyl-
substituted titanocene- and zirconocene dichlorides (see
Table 2). The less substituted metallocene dichlorides
show smaller angles due to a relieve of steric hin-
drance between the cyclopentadienyl ligands: 130.8° in
2.3. Crystal structure of 4 and 5
The structures of 4 and 5 were determined by single
crystal X-ray diffraction analysis. The selected bond
lengths and angles are given in Table 1. The isomor-
Table 1
a
ꢃ
Selected bond lengths (A) and angles (°) for non-equivalent molecules of 4 and 5
4a
Ti1–Cl1
2.331(1)
2.139(1)
Ti1–Cl2
Ti1–Cg(2)b
2.332(1)
2.128(1)
Ti1–Cg(1)b
Ti1–Cring
C–CCp ring
Cring–CPh
2.351(3)–2.548(3)
1.395(4)–1.434(4)
1.475(4)–1.483(4)
C–CPh ring
Cring–CMe
1.345(6)–1.404(4)
1.489(4)–1.500(4)
Cl1–Ti1–Cl2
c
93.63(3)
54.61(10)
Cg(1)–Ti1–Cg(2)b
sd
133.70(5)
37.5(2)
/
4b
Ti2–Cl4
Ti2–Cg(3)b
Ti2–Cring
C–CCp ring
Cring–CPh
2.327(1)
2.136(1)
Ti2–Cl3
Ti2–Cg(4)b
2.343(1)
2.132(1)
2.365(3)–2.533(3)
1.401(4)–1.429(4)
1.480(4)–1.485(4)
C–CPh ring
Cring–CMe
1.353(6)–1.401(4)
1.494(4)–1.507(4)
Cl3–Ti2–Cl4
c
91.40(4)
55.57(12)
Cg(3)–Ti2–Cg(4)b
sd
130.00(5)
40.5(2)
/
5a
Zr1–Cl1
Zr1–Cg(1)b
Zr1–Cring
C–CCp ring
2.423(1)
2.243(1)
Zr1–Cl2
Zr1–Cg(2)b
2.432(1)
2.240(1)
2.461(2)–2.630(2)
1.413(2)–1.437(2)
1.475(2)–1.486(2)
C–CPh ring
Cring–CMe
1.374(3)–1.406(2)
1.497(2)–1.505(2)
C
ring–CPh
Cl1–Zr1–Cl2
c
93.83(2)
54.34(6)
Cg(1)–Zr1–Cg(2)b
sd
132.11(3)
36.37(4)
/
5b
Zr2–Cl4
Zr2–Cg(3)b
Zr2–Cring
C–CCp ring
2.429(1)
2.247(1)
Zr2–Cl3
Zr2–Cg(4)b
2.443(1)
2.245(1)
2.480(2)–2.620(2)
1.412(2)–1.433(2)
1.479(3)–1.489(2)
C–CPh ring
Cring–CMe
1.384(3)–1.403(3)
1.494(3)–1.505(2)
C
ring–CPh
Cl3–Zr2–Cl4
c
92.21(2)
56.10(7)
Cg(3)–Zr2–Cg(4)b
sd
130.84(3)
37.81(4)
/
a Extreme values in the two independent molecules of the unit cell, the cyclopentadienyl ring atoms are denoted C101–C105 as shown in Fig. 1.
b Cg(1), Cg(2), Cg(3) and Cg(4) are centroids of the C(101–105), C(120–124), C(201–205), and C(220–224) cyclopentadienyl rings.
c Dihedral angle between the least-squares planes of the cyclopentadienyl rings.
d Torsion angles C(105)–Cg(1)–Cg(2)–C(124) and C(205)–Cg(3)–Cg(4)–C(224).

1626
J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
Table 3
Polymerization of ethene with 5, 6 and Cp2ZrCl2
a
Ab (ꢀ10ꢁ3
)
Tm (°C)
c
No.
Catalyst
Yield PE (g)
1.
2.
3.
4.
5.
6.
5
0.106
0.099
1.02
1.08
1.02
0.90
0.42
0.40
4.1
138.8
137.8
138.1
5
6
6
4.3
4.1
Cp2ZrCl2
Cp2ZrCl2
3.6
a Polymerization conditions: [Zr] ¼ 2.5 ꢀ 10ꢁ6 mol lꢁ1, MAO used as
co-catalyst (Al:Zr ¼ 10,000:1), 50 ml of toluene, temperature 20 °C,
ethylene pressure 4 bar, time 30 min.
b [A] (activity) ¼ kg PE/[(mol Zr) h bar].
Fig. 1. Molecular structure of 5a (30% probability thermal motion
ellipsoids) showing the atom numbering scheme. The hydrogen atoms
are omitted for clarity.
c Melting temperature of PE determined by DSC.
order more productive (see Table 3). Both the catalysts
gave high molecular weight polyethene of HDPE type as
evidenced by melting points spanned over a narrow
range of 137.8–138.8 °C. A much higher activity of the
MAO/6 catalyst is apparently caused by a lower steric
congestion at the zirconium cationic polymerization
center. The contribution of the net electronic effect
resulting from replacement of bulky 2,3-dimethyl-1,4-
diphenylcyclopentadienyl ligand by unsubstituted cy-
clopentadienyl is difficult to estimate as the geometry of
the metallocene skeleton seems to influence the energy
gap between the HOMO and LUMO orbitals [21]. On
the other hand, the MAO/4 catalytic system was prac-
tically inactive for polymerization of ethene. The ab-
sence of polymerization activity is apparently related to
an immediate colour change to blue upon addition of
MAO to the red toluene solution of 4 saturated with
ethene. It indicates an easy reduction of Ti(IV) to Ti(III)
which is facilitated in 4 by an electron-withdrawing ef-
fect of four phenyl groups decreasing the electron den-
sity on the titanium atom. This is in accord with a poor
polymerization activity of another strong but sterically
less demanding Lewis acid: [C5H4(C6F5)]2TiCl2 [20]. A
poor ethene polymerization activity of titanocene cata-
lysts which underwent the reduction to Ti(III) is well
known [22].
[ZrCl2{g5-(C5H2-1,3-Ph2-2-(C4H9))2}][6], 126.6° in
[ZrCl2{g5-(C5H3-1,2-Ph2)2}] [8], and and 126.9° in
[C5H4(C6F5)]2TiCl2 [20] . The phenyl groups are sub-
stantially rotated away from conjugative coplanar ori-
entation showing the following dihedral angles between
the least-squares planes of phenyl and cyclopentadienyl
rings: 22.41(11)°, 43.55(11)°, 12.70(19)°, 36.23(16)° for
4a; 40.57(14)°, 35.28(15)°, 43.16(13)°, 38.88(13)° for 4b;
22.14(6)°, 43.08(6)°, 11.58(11)°, 36.42(9)° for 5a and
40.93(8)°, 33.94(9)°, 43.40(7)°, 39.45(7)° for 5b. Both
complexes have almost ideal staggered conformation
with the unsubstituted carbon atoms placed at hinge
positions, torsion angles C(H)–Cg–Cg–C(H) being
37.5(2)° for 4a, 40.5(2)° for 4b, 36.37(4)° for 5a;
37.81(4)° for 5b. On the other hand, the values for Cl–
M–Cl angles in 4 (93.63(3)° in 4a and 91.40(4)° in 4b)
and 5 (93.83(2)° in 5a and 92.21(2)° in 5b) are consid-
erably smaller (especially in 5) than in octamethylated
metallocene dichlorides (Table 2), which can be related
to an electron-withdrawing effect of phenyl groups.
2.4. Ethene polymerization
The zirconium catalyst MAO/5 showed a moderate
activity while the analogous MAO/6 catalyst was by one
Table 2
Selected bond distances and angles for octa-substituted titanocene and zirconocene dichlorides
M–Cga;b(A)
M–Clb (A)
Cg–M–Cga (°)
\(Cp–Cp)c (°) Cl–M–Cl (°) Torsion angle (°) Ref.
ꢃ
ꢃ
4
2.136(1)
2.134(1)
2.109
2.332(1)
2.335(1)
2.344(2)
2.317(1)
2.300(2)
133.70(5)
130.00(5)
133.4
54.61(10)
55.57(12)
54.4
93.63(3)
91.40(4)
94.2(1)
96.8(1)
97.1(1)
37.5(2)
40.5(2)
36.0
This work
[TiCl2(g5-C5HMe4)2]
[TiCl2(g5-C5HPh4)2]
[17]
[18]
2.157(8)
2.161(3)
132.7(3)
133.6(7)
59.69
59.63
37.66
40.78
5
2.242(1)
2.246(1)
2.226(3)
2.428(1)
2.436(1)
2.434(3)
132.11(3)
130.84(3)
133.1 (1)
54.34(6)
56.10(7)
53.7(4)
93.83(2)
92.21(2)
97.61(9)
36.37(4)
37.81(4)
–
This work
[19]
[ZrCl2(g5-C5HMe4)2]
a Cg means ring centroid of the five-membered cyclopentadienyl ring.
b Average distance and standard deviation.
c Dihedral angle between the least-squares planes of the cyclopentadienyl rings.

J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
1627
3. Experimental
Ph), 134.94 (Cq, Ph), 144.26 (CH@CHPh), 166.09 (CO).
EI-MS, m=z (relative abundance): 205 (11), 204 (Mꢀþ;
46), 175 (8), 159 (7), 149 (69), 148 ([M–CH3CHCH2-
CH3]þ; 88), 147 (85), 146 (19), 132 (52), 131 ([M–
CH3CH(O)CH2CH3]þ; 100), 120 (13), 104 (55), 103
([PhCH@CH]þ; 83), 102 (51), 91 (15), 77 ([Ph]þ; 78), 74
(49), 73 (23). IR (neat, cmꢁ1): 3062 (vw), 3029 (vw), 2974
(m), 2937 (w), 2879 (w), 1709 (vs), 1638 (s), 1578 (w),
1496 (w), 1450 (m), 1379 (w), 1355 (m), 1311 (s), 1273
(s), 1203 (s), 1175 (vs), 1126 (m), 1115 (m), 1095 (m),
1072 (w), 1028 (m), 980 (m), 891 (w), 865 (w), 838 (vw),
768 (s), 733 (vw), 711 (m), 685 (m), 590 (vw), 572 (w),
542 (vw), 486 (w).
3.1. General procedures
All reactions with moisture- and air-sensitive com-
pounds were carried out under argon atmosphere using
standard Schlenk techniques. Solvents diethyl ether,
tetrahydrofuran (THF), hexane, and toluene were dried
by potassium benzophenone or Na–K alloy, and freshly
distilled prior to use. Cinnamic acid, 2-butanol, po-
lyphosphoric acid (PPA), phenyl bromide, ZrCl4 and
butyllithium (1.6 M in hexane) were obtained from Al-
drich and used as received. TiCl3(THF)3 [23] and
CpZrCl3(DME) [24] were prepared according to litera-
ture procedures. H NMR (500 MHz) and 13C NMR
1
(125 MHz) were measured on a Bruker DRX500 spec-
trometer in C6D6 or CDCl3 solution at 300 K. Chemical
shifts are given relative to the solvent signal (dH 7.15, dC
128.00 for C6D6 and dH 7.26, dC 77.36 for CDCl3). Mass
spectra were measured on a KRATOS Concept 32S
3.3. Preparation of 2,3-dimethyl-4-phenylcyclopent-2-en-
one (2)
3.3.1. Method A
PPA (500 g) was heated to 120 °C under mechanical
stirring and 2-butyl cinnamate (71 g) was added in one
portion. Then, the heating was stopped, a deep red
mixture was stirred for 30 min, and was quenched by
careful pouring on 500 ml of vigorously stirred slurry of
ice in water. A resulting dark red–brown emulsion was
stirred for another 30 min at 40 °C and then a red oil
separated from water phase. The water phase was ex-
tracted twice with 200 ml of diethyl ether. The organic
phases were combined, washed subsequently with satu-
rated water solution of Na2CO3 and 50 ml of saturated
NaCl solution, and dried over Na2SO4. The solvent was
evaporated and the residue was distilled under vacuum.
The fraction collected at 111–113 °C/1 mmHg partly so-
lidified at room temperature. Yield 27.4 g (42%). As re-
vealed from NMR measurements the product consisted
of two isomers: 2,3-dimethyl-4-phenylcyclopent-2-enone
(2) (95%) and 3-phenyl-4,5-dimethylcyclopent-2-enone
(20) (5%). The isomer 2 was isolated as white crystals
from ether/pentane solution.
ꢁ
instrument (Centre de Spectroscopie Moleculaire de
ꢁ
lÕUniversite de Bourgogne). Infrared spectra were re-
corded on a Nicolet Avatar FT-IR spectrometer in the
range 400–4000 cmꢁ1. Elemental analyses were per-
formed on a FISON EA 1108 CHNS instrument by the
ꢁ
Service de microanalyses du L.S.E.O. (Universite de
Bourgogne). Melting points were measured on Koffler
block and were uncorrected. Melting points of poly-
ethylenes were determined by DSC (Mettler 182E dif-
ferential scanning calorimeter) at a heating range of 10
°C minꢁ1
.
3.2. Preparation of 2-butylester of cinnamic acid (1)
Cinnamic acid (50 g, 0.34 mol) and a 3-fold molar
excess of 2-butanol (100 ml) were mixed with toluene
(200 ml), and concentrated sulphuric acid (2 ml) was
added. The mixture was refluxed under Dean-Stark
adapter until water was separating (for 20 h). A slightly
yellow mixture was subsequently washed with saturated
water solution of Na2CO3, water, and dried over
Na2SO4. The solution was concentrated in a rotary
evaporator and a residue was fractionally distilled in
vacuum. The core fraction distilled at 94–96 °C/0.5
mmHg (lit. 122 °C/2 mmHg [12]) as a colourless liquid.
Yield 67.4 g (97%).
2: m.p. 57–58 °C. 1H NMR (C6D6): 1.35 (s, 3H, CH3
5
[bCO]); 1.66 (q, JHH ¼ 1:0 Hz, 3H, CH3, [aCO]); 2.16
(dd, 2JHH ¼ 18:0 Hz, 3JHH ¼ 2:5 Hz, 1H, H [bCO]); 2.57
2
3
(dd, JHH ¼ 18:0 Hz, JHH ¼ 7:5 Hz, 1H, H [bCO]);
3.22–3.26 (m, 1H, H [bCO]); 6.75–6.80 (m, 2H, Ph);
7.00–7.09 (m, 3H, Ph). 13C{1H}(C6D6): 8.23 (CH3
[aCO]); 14.92 (CH3 [bCO]); 44.51 (CH2); 49.02 (CHPh);
127.01, 128.52, 129.03 (CH, Ph); 136.99, 142.76, 169.47
(Cq; [aCO], [bCO] and Ph); 206.67 (CO). EI-MS, m=z
(relative abundance): 187 (27), 186 (Mꢀþ; 82]), 171
([M–Me]þ; 68), 158 ([M–CO]þ; 45), 144 (26), 143 ([M–
MeCO]þ; 100), 142 (25), 141 (37), 129 (42), 128 ([M–
MeCO–Me]þ; 79), 127 (24), 115 (66), 109 (13), 104 (52),
103 (49), 102 (23), 91 (33), 78 (54), 77 ([Ph]þ; 65), 65
(24), 63 (20). IR (KBr, cmꢁ1): 3368 (w), 3053 (w), 2917
(m), 1689 (vs), 1643 (vs), 1600 (m), 1497 (m), 1455 (m),
1409 (m), 1378 (m), 1322 (s), 1281 (w), 1233 (vw), 1198
3
1H NMR (C6D6): 0.79 (t, JHH ¼ 7:5 Hz, 3H,
3
CH3CHCH2CH3), 1.12 (d, JHH ¼ 6:5 Hz, 3H,
CH3CHCH2CH3), 1.34–1.43 (m, 1H, CH3CHCH2CH3),
1.49–1.58 (m, 1H, CH3CHCH2CH3), 5.00 (pseudosextet,
3
1H, CH3CHCH2CH3), 6.41 (d, JHH ¼ 16:0 Hz, 1H,
CH@CHPh), 6.98–7.06 (m, 3H, Ph), 7.16–7.20 (m, 2H,
Ph), 7.74 (d, 3JHH ¼ 16:0 Hz, 1H, CH@CHPh). 13C{1H}
(C6D6): 9.81 (CH3CHCH2CH3), 19.61 (CH3CHCH2
CH3), 29.19 (CH3CHCH2CH3), 71.98 (CH3CHCH2
CH3), 119.34 (CH@CHPh), 128.21, 128.93, 130.07 (CH,

1628
J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
(vw), 1176 (w), 1142 (vw), 1070 (m), 932 (m), 918 (w),
879 (vw), 784 (w), 766 (s), 722 (w), 705 (s), 658 (w), 640
(vw), 581 (vw), 541 (vw), 486 (m), 468 (vw).
Ph), 7.21–7.28 (m, 4H, Ph), 7.30–7.35 (m, 4H, Ph).
13C{1H}(C6D6): 13.00 (CH3), 45.51 (CH2), 126.20,
128.14, 128.61 (CH, Ph), 138.16, 138.77, 139.84 (Cq; C–
CH3; C–Ph and Ph). EI-MS, m=z (relative abundance):
247 (23), 246 (Mꢀþ; 100), 231 ([M–Me]þ; 15), 216 (12),
215 (18), 149 (18), 148 (10), 131 (18), 115 (10), 103 (11),
77 ([Ph]þ; 12). IR (KBr, cmꢁ1): 3048 (s), 2991 (s), 2939
(s), 2917 (s), 2887 (s), 1957 (w), 1621 (w), 1595 (m), 1574
(w), 1492 (s), 1449 (s), 1437 (s), 1394 (w), 1371 (m), 1313
(w), 1279(vw), 1202 (m), 1182 (w), 1158 (vw), 1106 (w),
1066 (m), 1026 (w), 1001 (w), 982 (w), 924 (w), 884 (vw),
756 (vs), 731 (vw), 707 (vs), 654 (vw), 600 (vw), 575 (vw),
542 (w), 472 (vw). Calc. for C19H18: C, 92.64; H, 7.36.
Found: C, 92.41; H, 7.51%.
20: 1H NMR (C6D6): 0.86 (d, 3JHH ¼ 7:0 Hz, 3H, CH3
3
[bCO]), 1.13 (d, JHH ¼ 7:5 Hz, 3H, CH3 [aCO]), 1.87–
1.93 (m, 1H, H [aCO]), 2.57–2.63 (partially overlapped
by major isomer signal, m, 1H, H [bCO]), 6.26 (d,
4JHH ¼ 1:0 Hz, 1H, @CH), Ph signals are overlapped by
signals of major isomer. 13C {1H}(C6D6): 15.96 (CH3
[aCO]), 19.36 (CH3 [bCO]), 43.80 (CH [bCO]), 50.13
(CH [aCO]), 123.65 (olefinic C), 127.29, 128.89, 130.35
(CH, Ph), 134.18, 176.00 (Cq; Ph and [bCO]), 208.57
(CO).
3.3.2. Method B
2-Butyl cinnamate (21 g, 0.1 mol) was added to 190
g of a 1:10 mixture P2O5–CH3SO3H and the mixture
was stirred for 2 h at room temperature. Resulting
deep red oil was transferred to separatory funnel and
slowly dropped to 300 ml of vigorously stirred water.
The product was extracted with chloroform (4 ꢀ 100
ml). Combined organic phases were washed subse-
quently with saturated water solution of Na2CO3 and
50 ml of saturated NaCl solution, and dried over
Na2SO4. The solvent was evaporated and the residue
was distilled at low pressure. A slightly yellow liquid
was obtained at 100–102 °C/0.5 mmHg. Yield 8.2 g
(43%). According to NMR analysis the product con-
tained in addition to isomers 2 and 20 ca. 10% of
starting 2-butyl cinnamate.
3.5. Preparation of bis(g5-2,3-dimethyl-1,4-diphenylcy-
clopentadienyl)dichlorotitanium (4)
Hexane solution of butyllithium (5.40 ml, 1.6 M,
8.6 mmol) was dropwise added to a pre-cooled solution
of 3 (1.924 g, 7.82 mmol) in 60 ml of diethyl ether. The
reaction mixture was warmed to room temperature and
stirred overnight. A white precipitate was filtered, wa-
shed with diethyl ether (3 ꢀ 10 ml), and dissolved in
40 ml of THF. This solution was cooled to )78 °C and
TiCl3(THF)3 (1.449 g, 3.91 mmol) was successively ad-
ded. The reaction mixture was slowly warmed to room
temperature and then refluxed for 12 h. The resulting
dark green mixture was cooled to room temperature and
carbon tetrachloride (2 ml) was added, immediately
turning the colour to deep red. After 1 h stirring at 40
°C, the solvents were evaporated under vacuum, and a
solid residue was extracted with toluene (5 ꢀ 20 ml). The
volume of dark red toluene extracts was concentrated to
ca. 10 ml and the solution was layered with pentane
(30 ml). Dark red crystals which grew up after several
hours were isolated. Yield 1.80 g (76%).
m.p. 276 °C. 1H NMR (C6D6): 2.28 (s, 6H,
Cp(CH3)2), 6.55 (s, 1H, CpH), 6.88–6.93 (m, 4H, Ph),
6.97 (tt, 3JHH ¼ 7:5 Hz, 4JHH ¼ 1:5 Hz, 2H, C(4)H, Ph),
7.11–7.14 (m, 4H, Ph). 13C{1H}(C6D6): 14.34 (CpCH3),
111.30 (CH, CpMe2Ph2H), 127.35, 128.24, 128.91 (CH,
Ph), 130.55, 134.40, 136.15 (Cq; C–CH3; C–Ph and Ph).
EI-MS, m=z (relative abundance): 610 (5), 609 (4), 608
(Mꢀþ; 8), 573 ([M–Cl]þ; 9), 365 (11), 364 (5), 363 ([M–
C5Me2Ph2H]þ; 16), 347 (8), 246 (29), 245
([C5Me2Ph2H]þ; 100), 244 (8), 230 (14), 229 (16), 228
(13), 215 (18), 167 (7), 165 (10), 115 (8). IR (KBr, cmꢁ1):
3052 (m), 3030 (w), 2917 (s,b), 2855 (s,b), 1598 (m), 1575
(w), 1518 (vw), 1493 (w), 1473 (w), 1448 (m), 1374 (w),
1202 (vw), 1182 (vw), 1154 (vw), 1107 (w), 1067 (w),
1028 (w), 1002 (vw), 981 (vw), 917 (vw), 788 (vs,b), 763
(s), 697 (s), 674 (m), 659 (m), 646 (m), 611 (w), 585 (w),
542 (vw), 500 (vw), 415 (m). Calc. for C38H34Cl2Ti: C,
74.89; H, 5.62. Found: C, 75.23; H, 6.14%.
3.4. Preparation of 2,3-dimethyl-1,4-diphenylcyclopenta-
1,3-diene (3)
A solution of phenylbromide (12.2 g, 78 mmol) in 40
ml of diethyl ether was added dropwise to magnesium
turnings (2.3 g, 95 mmol) in diethyl ether (150 ml) at
the rate maintaining a mild reflux. After the reaction
ceased, the mixture was refluxed for 30 min. After
cooling, a mixture of dimethylphenylcyclopentenones
(14.1 g, 76 mmol) in 50 ml of diethyl ether was slowly
added, and the reaction mixture was refluxed for 2 h.
Resulting grey–green mixture was poured onto a 100
ml mixture of ice and water acidified with 10 ml of
concentrated HCl. The product was extracted with di-
ethyl ether (4 ꢀ 100 ml), volume of combined organic
phases was reduced to ca. 100 ml, and a few crystals of
iodine were added. After standing overnight solid 3 was
obtained as a result of the alcohol dehydration. The
crude product was washed with large amount of etha-
nol and dried in vacuum to give 11.5 g (62%) of white
crystalline solid.
1
5
m.p. 156–157 °C. H NMR (C6D6): 1.94 (t, JHH
¼
5
1:8 Hz, 6H, @CCH3), 3.47 (septuplet, JHH ¼ 1:8 Hz,
3
4
2H, CH2), 7.10 (tt, JHH ¼ 7:2 Hz, JHH ¼ 1:8 Hz, 2H,

J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
1629
3.6. Preparation of bis(g5-2,3-dimethyl-1,4-diphenylcy-
clopentadienyl)dichlorozirconium (5)
then the solution was slowly cooled, finally to )18 °C.
Slightly yellow microcrystals were isolated, washed with
pentane and dried in vacuum. Yield 0.345 g (42%).
m.p. 250 °C. 1H NMR (CDCl3): 2.36 (s, 6H,
Cp(CH3)2), 6.16 (s, 5H, CpH), 6.94 (s, 1H, CpMe2Ph2
H), 7.14 (tt, 3JHH ¼ 7:5 Hz, 4JHH ¼ 1:5, 2H, C(4)H, Ph),
7.41–7.45 (m, 4H, C(3)H, Ph), 7.47–7.51 (m, 4H, C(2)H,
Ph). 13C{1H}(CDCl3): 13.69 (CpCH3), 108.43 (CH,
CpMe2Ph2H), 116.40 (CH, Cp), 128.01, 128.75, 129.04
(CH, Ph), 126.32, 130.78, 134.57 (Cq; C–CH3; C–Ph and
Ph). EI-MS, m=z (relative abundance): 476 (29), 475 (18),
474 (64), 473 (36), 472 (Mꢀþ; 95), 471 (43), 470 (89), 411
(31), 410 (16), 409 (67), 408 (33), 407 ([M–Cp]þ; 100),
406 (40), 405 (93), 369 (17), 368 (9), 367 (18), 366 (10),
365 (12), 329 (5), 245 ([C5Me2Ph2H]þ; 15), 229 (23), 228
(15), 227 ([CpZrCl2]þ; 19), 225 (15), 215 (13), 165 (9). IR
(KBr, cmꢁ1): 3103 (s), 3075 (s), 3062 (s), 3033 (s), 2982
(m), 2958 (m), 2914 (s), 1599 (m), 1576 (w), 1512 (w),
1502 (w), 1471 (m), 1447 (s), 1381 (m), 1148 (w), 1109
(vw), 1074 (w), 1020 (m), 1014 (m), 934 (vw), 913 (vw),
851 (s), 818 (vs), 769 (vs), 764 (vs), 743 (w), 698 (vs), 670
(w), 656 (w), 648 (w), 613 (w), 585 (w), 532 (w), 461 (vw),
406 (vw). Calc. for C24H22Cl2Zr: C, 61.00; H, 4.69.
Found: C, 60.80; H, 4.73%.
Zirconium tetrachloride (0.655 g, 2.81 mmol) was
added to a mixture of 2,3-dimethyl-1,4-diphenylcyclo-
pentadienyl lithium salt (1.417 g, 5.62 mmol, prepared
as for 4) in 50 ml of toluene and the mixture was ref-
luxed for 2 days. Then, the resulting mixture was fil-
tered, a clear brown filtrate was reduced in volume to
ca.7 ml and cooled to )18 °C to afford a yellow powder
of 5. The product was isolated, washed with pentane
(2 ꢀ 5 ml) and dried in vacuum. Yield 1.14 g (62%).
m.p. 231 °C. 1H NMR (C6D6): 2.20 (s, 6H,
Cp(CH3)2), 6.28 (s, 1H, CpH), 6.92–7.00 (m, 6H, Ph),
7.16–7.19 (m, 4H, Ph). 13C{1H}(C6D6): 13.37 (CpCH3),
107.60 (CH, CpMe2Ph2H), 127.05, 128.47, 128.71 (CH,
Ph), 130.36, 134.06 (Cq; C–Ph and Ph). 1H NMR
(CDCl3): 2.28 (s, 6H, Cp(CH3)2), 6.29 (s, 1H, CpH),
3
7.03–7.10 (m, 6H, Ph), 7.14 (tt, JHH ¼ 7:0 Hz,
4JHH ¼ 1:5 Hz, 2H, C(4)H, Ph). 13C{1H}(CDCl3): 13.68
(CpCH3), 107.81 (CH, CpMe2Ph2H), 127.26, 128.53,
128.58 (CH, Ph), 127.84, 130.46, 133.71 (Cq; C–CH3; C–
Ph and Ph). EI-MS, m=z (relative abundance): 656 (18),
655 (15), 654 (39), 653 (23), 652 (Mꢀþ; 54), 651 (29), 650
(46), 636 (13), 635 (9), 634 (15), 411 (29), 410 (16), 409
(66), 408 (33), 407 ([M–C5Me2Ph2H]þ; 100), 406 (18),
405 (94), 393 (11), 391 (17), 390 (10), 389 (25), 371 (10),
369 (19), 367 (19), 365 (10), 246 (14), 245
([C5Me2Ph2H]þ; 24), 244 (11), 229 (12), 228 (11), 215
(11), 165 (9). IR (KBr, cmꢁ1): 3056 (s), 3032 (s), 2978
(m), 2966 (m), 2922 (s), 2866 (m), 1684 (w), 1599 (m),
1576 (m), 1514 (m), 1504 (m), 1470 (s), 1452 (s), 1379
(m), 1303 (vw), 1183 (w), 1155 (m), 1105 (vw), 1077 (w),
1032 (w), 1006 (vw), 919 (vw), 852 (m), 843 (m), 818 (m),
764 (vs), 715 (m), 695 (vs), 670 (w), 648 (m), 638 (w), 611
(m), 585 (vw), 520 (vw), 500 (w), 418 (w). Calc. for
C38H34Cl2Zr: C, 69.91; H, 5.25. Found: C, 69.36; H,
5.39%.
3.8. X-ray crystallography
The red crystals of 4 were grown from toluene/hexane
solution, the yellow crystals of 5 were obtained by
pentane gas-phase transfer into a dichloromethane so-
lution. All diffraction data were collected on a Nonius
KappaCCD diffractometer. The structures were solved
by direct methods (SIR-92 [25]) and refined by weighted
full-matrix least-squares on F 2
(SHELXL97 [26]). All
non-hydrogen atoms were refined with anisotropic
thermal motion parameters. The hydrogen atoms were
included in calculated position. Relevant crystallo-
graphic data are collected in Table 4.
3.7. Preparation of (g5-2,3-dimethyl-1,4-diphenylcyclo-
pentadienyl)(g5-cyclopentadienyl) dichlorozirconium (6)
3.9. Ethene polymerization
€
A 250 ml Buchi glass autoclave equipped with a
A mixture of solid dimethyldiphenylcyclopentadienyl
lithium salt (0.436 g, 1.73 mmol) and solid cyclopenta-
dienyltrichlorozirconium(dimethoxyethane) (0.610 g,
1.73 mmol) was cooled to )50 °C and 20 ml of toluene
was added. The reaction mixture was stirred for 30 min
at this temperature and then allowed to warm to room
temperature. A resulting voluminous yellow slurry was
refluxed for additional 14 h. The toluene was removed in
vacuum and traces of 2,3-dimethyl-1,4-diphenylcyclo-
pentadiene were sublimed off at 105–125 °C/0.5 mmHg
from a solid residue. The residue was extracted with 80
ml of toluene and the formed suspension was filtered
through cellite pad. A clear yellow filtrate was concen-
trated to ca. 30 ml, the product dissolved under boil, and
magnetic stirrer was filled with argon and toluene and
the solution of methylalumoxane (10 wt% in toluene;
Al:M ¼ 10,000:1) was injected. After stirring at 20 °C for
10 min, a solution of metallocene dichloride in toluene
was injected (total volume of polymerization solution
was 50 ml and concentration of metallocene dichloride
was 2.5 ꢀ 10ꢁ6 M for all experiments). After preactiva-
tion for 10 min, the autoclave was pressurized with 4 bar
of ethene for 30 min and stirred at 400 rpm. Finally, the
autoclave was vented and the polymerization was
quenched with 10% HCl in ethanol (80 ml). A precipi-
tated polymer was stirred in acidified ethanol for 1 h,
filtered, washed with water and ethanol, and dried in
vacuum to constant weight.

1630
J. Pinkas et al. / Journal of Organometallic Chemistry 689 (2004) 1623–1630
Table 4
Crystallographic data, data collection and structure refinement data
for compounds 4 and 5a
[2] (a) W. Kaminsky, M. Arndt, Adv. Polym. Sci. 127 (1997) 143;
(b) W. Kaminsky, J. Chem. Soc., Dalton Trans. (1998)
1413.
€
[3] (a) P.C. Mohring, N.J. Coville, J. Organomet. Chem. 479 (1994)
1;
(b) H.G. Alt, A. Koppl, Chem. Rev. 100 (2000) 1205;
4
5
Chemical formula
Molecular weight
Crystal system
Space group
T (K)
C38H34Cl2Ti
609.45
C38H34Cl2Zr
652.77
€
(c) J.C.V. Chien, A.J. Razavi, J. Polym. Sci., Part A 26 (1988)
2369;
Monoclinic
P21=c (No. 14)
293
Monoclinic
P21=c (No. 14)
150
(d) W. Kaminsky, A. Laban, Appl. Catal. A 222 (2001) 47.
[4] B. Rieger, T. Repo, G. Jany, Polym. Bull. 35 (1995) 87.
[5] T. Repo, G. Jany, K. Hakala, M. Klinga, M. Polamo, M. Leskela,
ꢃ
a (A)
17.7050(3)
15.3880(3)
22.4210(4)
90.000
17.6200(1)
15.4060(1)
22.4510(2)
90.000
€
ꢃ
b (A)
B. Rieger, J. Organomet. Chem. 549 (1997) 177.
[6] B.Y. Lee, J.W. Han, Y.K. Chung, S.W. Lee, J. Organomet. Chem.
587 (1999) 181.
ꢃ
c (A)
a (°)
b (°)
c (°)
Z
96.7590(11)
90.000
96.9490(3)
90.000
[7] X. Deng, B. Wang, S. Xu, X. Zhou, L. Yang, Y. Li, F. Zhou, J.
Mol. Catal. A 184 (2002) 57.
8
8
[8] F. Zhang, Y. Miu, L. Zhao, Y. Zhang, W. Bu, C. Chen, H. Zhai,
H. Hong, J. Organomet. Chem. 613 (2000) 68.
[9] (a) C.W. Coates, R.M. Waymouth, Science 267 (1995) 219;
Crystal size (mm3)
0.40 ꢀ 0.35 ꢀ 0.12
1.335
0.485
0.35 ꢀ 0.32 ꢀ 0.22
1.433
0.567
dcalc (g cmꢁ3
)
l (Mo Ka) (mmꢁ1
)
ꢁ
(b) A.K. Rappe, M.A. Pietsch, J. Am. Chem. Soc. 118 (1996)
10908;
F (0 0 0)
h range (°)
hk l range
2544
2688
1–27.5
2.99–25.02
)21/21, )18/16,
)26/26
7289
747
(c) J.L.M. Petoff, M.D. Bruce, R.M. Waymouth, A. Masood,
T.K. Lal, R.W. Quan, S. Berend, Organometallics 16 (1997)
5909;
)22/22, )19/19,
)29/29
11678
Diffraction collected
Parameters
(d) M.D. Bruce, G.W. Coates, E. Hauptman, R.W. Waymouth,
J.W. Ziller, J. Am. Chem. Soc. 119 (1997) 11174;
(e) Ch.D. Tagge, R.L. Kravchenko, T.K. Lal, R.W. Waymouth,
Organometallics 18 (1999) 380.
747
R; wR½I > 2rðIÞꢂ
R; wR (all data)
S
0.0436, 0.0989
0.0779, 0.1152
1.029
0.0291, 0.0693
0.0386, 0.0746
1.030
[10] (a) D.L. Green, O.A. Villalta, D.M. Macias, A. Gonzales, W.
Tikkanen, B. Schick, K. Kantardjieff, Inorg. Chem. Commun. 2
(1999) 311;
ꢁ3
ꢃ
qmax;min (e A
)
0.255, )0.310
0.420, )0.587
P
P
P
2
a RðF Þ ¼
jjFoj ꢁ jFcjj=
jFoj; wRðF 2Þ ¼ ½ ðwðFo2 ꢁ Fc2Þ Þ=
P
4. Supplementary material
P
(b) D.L. Green, A. Chau, M. Monreal, I. Cruz, T. Wenj, W.
Tikkanen, B. Schick, K. Kantardjieff, J. Organomet. Chem. 682
(2003) 8.
2
2
1=2
ð
wðFo2Þ Þꢂ1=2, S ¼ ½ ðwðFo2 ꢁ F 2Þ Þ=ðNdiffrs ꢁ NparamsÞꢂ
.
c
[11] D. Feitler, G.M. Whitesides, Inorg. Chem. 15 (1976) 466.
[12] J. Munch-Petersen, J. Org. Chem. 22 (1957) 170.
[13] J.M. Conia, M.L. Leriverend, Bull. Soc. Chim. (France) 8–9
(1970) 2981.
Crystallographic data, excluding structure factors,
have been deposited at the Cambridge Crystallographic
Data Centre (4: 215219, 5: CCDC-215744). Copies of
the data can be obtained free of charge upon application
to The director, CCDC, 12, Union Road, Cambridge
CB2 1EZ, UK (fax: +44-1223-336033; e-mail: de-
posit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
[14] P.E. Eaton, G.R. Carlson, J.T. Lee, J. Org. Chem. 38 (1973) 4071.
[15] R.C. Gilmore Jr., J. Am. Chem. Soc. 73 (1951) 5879.
[16] C.M. Fendrick, L.D. Schertz, V.W. Day, T.J. Marks, Organo-
metallics 7 (1988) 1828.
ꢁꢀ
[17] V. Varga, J. Hiller, R. Gyepes, M. Polasek, P. Sedmera, U.
Thewalt, K. Mach, J. Organomet. Chem. 538 (1997) 63.
[18] K.H. Thiele, F. Rehbaum, H. Baumann, H. Schumann, F.H.
€
Gorlitz, R. Weimann, Z. Anorg. Allg. Chem. 613 (1992) 76.
[19] Ch. Janiak, U. Verteeg, K.C.H. Lange, R. Weimann, E. Hahn, J.
Organomet. Chem. 501 (1995) 219.
Acknowledgements
[20] R.J. Maldanis, J.C.V. Chien, M.D. Rausch, J. Organomet. Chem.
599 (2000) 107.
This work was supported by Academy of Sciences of
the Czech Republic (Grant No. K4050111). J.P. thanks
French Government for financial support (Grant for
doctorat No. 20006842).
ꢁꢀ
[21] J. Langmaier, Z. Samec, V. Varga, M. Horacek, K. Mach, J.
Organomet. Chem. 579 (1999) 348.
[22] U. Bueschges, J.C.V. Chien, J. Polym. Sci., Polym. Chem. Ed. 27
(1989) 1525.
[23] L.E. Manzer, Inorg. Synth. 21 (1982) 135.
References
[24] E.C. Lund, T. Livinghouse, Organometallics 9 (1990) 2426.
[25] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C.
Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Crystallogr. 32 (1999) 115.
[1] (a) H. Sinn, W. Kaminsky, Adv. Organomet. Chem. 18 (1980) 99;
(b) H. Sinn, W. Kaminsky, H.J. Vollmer, R. Woldt, Angev.
Chem., Int. Ed. Engl. 19 (1980) 390;
[26] G.M. Sheldrick, SHELXL97, Program for Crystal Structure
€
Refinement from Diffraction Data, University of Gottingen,
(c) W. Kaminsky, M. Miri, H. Sinn, R. Woldt, Macromol. Chem.
Rapid Commun. 4 (1983) 417.
€
Gottingen, Germany, 1997.