Synthesis, structural and chemical characterization of unsaturated C4- and C10-bridged group-4 ansa-metallocenes obtained through a ring-closing olefin metathesis reaction

Article abstract of DOI:10.1002/1099-0682(200210)2002:10<2633::AID-EJIC2633>3.0.CO;2-4

Bis[(5-hexenyl)cyclopentadienyl]zirconium dichloride (3) underwent ring-closure olefin metathesis with loss of ethylene when treated with 10 mol % of the [Cl₂(PCy₃)₂Ru=CHPh] catalyst in refluxing dichloromethane, to yield

Full text of DOI:10.1002/1099-0682(200210)2002:10<2633::AID-EJIC2633>3.0.CO;2-4

FULL PAPER
Synthesis, Structural and Chemical Characterization of Unsaturated C4- and
C10-Bridged Group-4 ansa-Metallocenes Obtained Through a Ring-Closing
Olefin Metathesis Reaction
Doris Hüerländer,[a] Nina Kleigrewe,[a] Gerald Kehr,[a] Gerhard Erker,*[a] and
Roland Fröhlich[a][‡]
Keywords: Carbenes / Metallocenes / Metathesis / Olefins / Ruthenium / Zirconium
Bis[(5-hexenyl)cyclopentadienyl]zirconium dichloride (3) un-
derwent ring-closure olefin metathesis with loss of ethylene
when treated with 10 mol % of the [Cl2(PCy3)2Ru=CHPh]
catalyst in refluxing dichloromethane, to yield the large
ansa-zirconocene complex [dec-5-ene-1,10-diylbis(η5-cyclo-
pentadienyl)]ZrCl2 (trans-4). Characterization by NMR and
by X-ray diffraction revealed that the isolated complex con-
tained a trans-C=C double bond inside the ansa bridge. Sim-
for ethylene polymerization [after activation of the metallo-
cene dichloride 8 with MAO (methylalumoxane) or treatment
of the corresponding dimethylmetallocene complex 9 with
B(C6F5)3]. Complex 8 was also converted into a mixture of (s-
cis- and s-trans-η4-butadiene)-ansa-metallocene complexes
(s-cis-15/s-trans-15 = 4:5) by treatment with (butadiene)-
magnesium. The C=C double bond of cis-8 could be hydro-
borated with 9-BBN or with the H−B(C6F5)2 reagent.
ilarly, bis[(allyl)cyclopentadienyl]ZrCl2 (7) gave the ansa- Li+[B(C6F5)4−] added to cis-8 to yield an interesting solid-
metallocene [but-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zir-
conium dichloride (cis-8) when treated with the same ruth-
enium metathesis catalysts (10 mol %) under similar condi-
state chain structure in which the [Zr]Cl2 unit and the o-/m-
F pairs of two −C6F5 groups were found to be in contact with
the central lithium cation in a distorted octahedral coordina-
tions, except that a cis-C=C double bond was now found to tion environment (as shown by X-ray diffraction).
be present (shown by NMR and X-ray diffraction). The cis-8
complex was used as a homogeneous Ziegler−Natta catalyst
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
The CϭC double bonds of alkenyl side chains at the Cp
rings are functional groups compatible with many Group
4 metallocene features, and are easily introduced.[8,9,22Ϫ25]
Modern variants of the olefin metathesis reaction, em-
ploying defined molecular Group 6 or Group 8 alkylidene
complexes, can efficiently use alkenyl functional groups for
carbonϪcarbon coupling.[26Ϫ28] Intramolecular variants
(‘‘ring-closure metathesis’’, RCM) has become an especially
useful tool in organic synthesis.[29Ϫ36] We have employed
such an olefin metathesis reaction for the intramolecular
CϪC coupling of bis[(ω-alkenyl)cyclopentadienyl]ZrCl2
complexes to yield the respective CϭC unsaturated ansa-
metallocene complexes. Two representative examples are de-
scribed, including their structural characterization and
some chemical features of these easily available new sys-
tems.[37]
ansa-Metallocenes of the Group 4 metals have become of
great importance, especially as components of homogen-
eous ZieglerϪNatta catalyst systems.[1] Their synthesis in
most cases involves nucleophilic substitution routes with
Cp-anion equivalents and the respective bis(electrophile) of
the bridging unit to build up the ligand framework before
it is attached to the transition metal atom. This synthetic
scheme has been followed in many cases, providing the ubi-
quitous ansa-metallocenes with small bridging units (e.g.
SiR2, CH2ϪCH2 etc.)[2Ϫ6] as well as the few examples of
‘‘large ansa-metallocenes’’ so far described in the
literature.[7Ϫ10] A sizeable number of alternatives of linked
bis(Cp) ligand syntheses has been reported in the
literature,[11Ϫ19] but only very few in which selective organic
transformations were carried out by coupling functional
groups at the Cp ligands at the Group 4 metallocene
stage.[20,21]
Results and Discussion
Synthesis and Characterization of the ansa-Metallocenes
[a]
Organisch-Chemisches Institut der Universität Münster,
Corrensstrasse 40, 48149 Münster, Germany
Bis[(5-hexen-1-yl)cyclopentadienyl]zirconium dichloride
(3) was prepared by a procedure analogous to that de-
scribed by us in the literature: treatment of CpϪsodium
[‡]
X-ray crystal structure analyses
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/1010Ϫ2633 $ 20.00ϩ.50/0
2633

D. Hüerländer, N. Kleigrewe, G. Kehr, G. Erker, R. Fröhlich
FULL PAPER
Scheme 1
with hexenyl bromide, followed by deprotonation (MeLi)
and transmetallation furnished complex 3 in 38% yield (see
Scheme 1).[8,22] Intramolecular olefin metathesis was carried
out catalytically on 3 by treatment with 10 mol % of the
‘‘Grubbs catalyst’’ benzylidenedichlorobis(tricyclohexyl-
phosphane)ruthenium.[38,39] In dilute solution, with use of
a syringe pump for addition of 3 in dichloromethane to the
metathesis catalyst, the reaction can largely be kept in the
intramolecular regime. Crystallization from toluene gave
the ‘‘large ansa-zirconocene dichloride complex’’ as a white
crystalline solid in 25% yield.
Single crystals of 4 suitable for X-ray crystal structure
analysis were obtained from [D6]benzene at room temper-
ature. The crystals were very thin needles, and the diffrac-
tion power was therefore weak, giving data of limited accu-
racy. The structure features an ansa-metallocene containing
˚
a trans-CϭC double bond [C10ϪC11: 1.291(18) A] in its
centre. The large ‘‘13-membered’’ ring displays a crown-
shaped conformation. The metallocene conformation is
such that the bridging ring system is completely oriented
toward a lateral sector of the bent metallocene wedge
[‘‘bis(lateral) syn’’ conformation, see Figure 1].[10,40,41] The
zirconium atom in complex 4 is pseudotetrahedrally coord-
inated by the two η5-Cp rings [Cp(centroid)ϪZr: 2.193 and
˚
2.216 A, Cp(centroid)ϪZrϪCp(centroid) angle 129.4°,
˚
˚
ZrϪCl2 2.430(3) A, ZrϪCl1 2.437(3) A, Cl1ϪZrϪCl2
angle: 98.2(1)°] in a largely unstrained fashion.
Figure 1. Two views of the organometallic olefin metathesis prod-
˚
uct 4; selected bond lengths [A] and angles [°]: ZrϪCl1 2.437(3),
ZrϪCl2 2.430(3), C5ϪC6 1.526(14), C6ϪC7 1.489(14), C7ϪC8
1.516(14), C8ϪC9 1.500(17), C9ϪC10 1.472(19), C10ϪC11
1.291(18), C11ϪC12 1.455(23), C12ϪC13 1.538(22), C13ϪC14
1.505(20), C14ϪC15 1.528(19), C15ϪC16 1.510(16); Cl1ϪZrϪCl2
98.2(1), C5ϪC6ϪC7 113.6(9), C6ϪC7ϪC8 113.8(9), C7ϪC8ϪC9
112.3(9), C8ϪC9ϪC10 111.7(11), C9ϪC10ϪC11 128.0(15),
In the NMR spectra the signals of a major (Ͼ 95%) and
a minor component could be seen. Whereas the minor com-
pound has remained unidentified so far (it could be the cis
isomer or an oligomer), the major product is likely to be
identical to trans-4 as identified by X-ray diffraction. This C10ϪC11ϪC12
126.7(16),
112.0(12),
118.0(11);
179.2(11),
C11ϪC12ϪC13
C13ϪC14ϪC15
C5ϪC6ϪC7ϪC8
C7ϪC8ϪC9ϪC10
114.0(13),
116.3(13),
Ϫ175.4(10),
71.2(14),
is indicated by the typical 13C NMR shift of the allylic
C12ϪC13ϪC14
C14ϪC15ϪC16
ϪCH2ϪCHϭ resonance (C-9) at δ ϭ 31.9 ppm [δ(C-10) ϭ
131.5 ppm]. The remaining CH2 shifts of the bridging hy-
drocarbyl chain are found at δ ϭ 29.3 (C-6), 26.4 (C-7) and
28.5 (C-8) ppm (for atom numbering scheme see Scheme 1).
C6ϪC7ϪC8ϪC9
C8ϪC9ϪC10ϪC11 -107.6(15), C9ϪC10ϪC11ϪC12 176.2(14),
C10ϪC11ϪC12ϪC13 -108.4(16), C11ϪC12ϪC13ϪC14 65.1(19),
C12ϪC13ϪC14ϪC15 -175.6(13), C13ϪC14ϪC15ϪC16 74.4(18)
1
The corresponding H NMR resonances occur at δ ϭ 2.52
(6-H), 1.22 (7-H), 1.30 (8-H), 2.01 (9-H) and 5.25 (olefinic tions. Oligomeric by-products were removed by filtration
10-H) ppm. and the product 8 was purified by fractional crystallization.
The synthesis of bis(allylcyclopentadienyl)zirconium Eventually, the isomerically pure complex cis-8 was ob-
dichloride (7) was carried out analogously to the procedure tained as a colourless, crystalline material in ca. 50% yield.
described by us previously (Scheme 2).[22] The ring-closing
The X-ray crystal structure analysis of 8 (single crystals
metathesis reaction was carried out by treatment of 7 with were obtained from [D6]benzene at room temperature)
Cl2(PCy3)2RuϭCHPh under high-dilution reaction condi- again shows the presence of an unconstrained ansa-metallo-
2634
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642

Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes
FULL PAPER
Scheme 2
cene framework. The metalϪC(Cp) bond lengths are in a
˚
rather narrow range between 2.486(2) A (ZrϪC13) and
˚
2.536(2) A (ZrϪC11). The Cp(centroid)ϪZrϪCp(centroid)
angle amounts to an ideal bent metallocene value of
130.0°.[42] The Cl1ϪZrϪCl2 angle in 8 [95.95(2)°] is only
marginally smaller than that in the parent compound
Cp2ZrCl2.[43] ZrϪCl1 [2.437(1) A] and ZrϪCl2 [2.455(1) A]
are very similar in lengths.
˚
˚
The ansa-metallocene complex 8 features an endocyclic
˚
cis-carbonϪcarbon double bond [C16ϪC26 1.319(3) A].
This value is in the range typical for an uncoordinated CϭC
bond.[44] Close inspection reveals that there is no immediate
coordinative interaction between the cis-CϭC double bond
inside the ansa bridge and its adjacent, slightly electron-
deficient Group 4 metal centre. The observed Zr···C16/C26
˚
distances of ca. 4 A rule out any significant direct interac-
tion. Consequently, an eclipsed metallocene conformation
is attained in complex cis-8, with the C10ϪC15 and
C20ϪC25 vectors oriented to the same lateral sector of the
bent metallocene wedge and the ϪCH2ϪCHϭCHϪCH2Ϫ
unit bent back towards the back side of the metallocene
framework (as illustrated by the top view projection of cis-
8 in Figure 2).
Figure 2. Top and side views of the molecular structure of complex
˚
cis-8; selected bond lengths [A] and angles [°]: ZrϪCl1 2.437(1),
ZrϪCl2 2.455(1), C10ϪC15 1.513(3), C15ϪC16 1.496(3),
C16ϪC26 1.319(3), C26ϪC25 1.503(3), C25ϪC20 1.518(3);
Cl1ϪZrϪCl2 95.95(2), C10ϪC15ϪC16 114.7(2), C15ϪC16ϪC26
126.2(2), C16ϪC26ϪC25 126.1(2), C26ϪC25ϪC20 112.5(2);
C10ϪC15ϪC16ϪC26 Ϫ83.5(3), C15ϪC16ϪC26ϪC25 0.9(3),
C16ϪC26ϪC25ϪC20 86.0(3)
In solution one finds a single set of NMR signals, indicat-
ing that there is only one isomer present. This shows a 13C
NMR signal of the allylic C-6 CH2ϪCHϭ carbon centre
(see Scheme 1) at δ ϭ 24.8 ppm, consistent with the cis-8
structure (trans-4 shows the analogous ϪCH2ϪCHϭ signal
at δ ϭ 31.9 ppm, see above). In addition, there are the ol-
efinic ϪCHϭ resonance at δ ϭ 129.7 ppm and three Cp
signals at δ ϭ 119.3, 115.3 (both CH) and δ ϭ 121.2 ppm
(C). The pairwise identical C-2/C-5 and C-3/C-4 resonances
indicate rapid conformational equilibration of cis-8 on the
NMR timescale. Probably both the CpϪZr rotation and the
inversion of the metallacycle that includes the ansa bridge
that this Gibbs activation energy primarily characterises the
inversion barrier of the ansa-metallacycle, but it is in prin-
ciple possible that this has coincided with ‘‘freezing’’ of the
CpϪM rotation on the NMR timescale at this very
temperature.[48Ϫ50]
Reactions of the ansa-Metallocenes
Treatment of the ansa-zirconocene dichloride 8 with
atoms are fast.[45] Consequently, only two C5H4 resonances methyllithium (2 equiv.) gave the corresponding dimethyl-
1
are observed in the H NMR spectrum of cis-8 at ‘‘high’’ metallocene complex 9 {1H/13C NMR of [Zr](CH3)2: δ ϭ
temperatures. In a CDFCl2/CDF2Cl mixture[46] at 253 K Ϫ0.05/31.0 ppm (1JCH ϭ 117 Hz) in [D6]benzene}. Treat-
1
this pair of H NMR Cp signals is observed at δ ϭ 6.32 ment of 9 with B(C6F5)3 in [D8]toluene with NMR mon-
and 6.66 ppm. On lowering the temperature these signals itoring generated the ion-pair 10 {1H NMR of [Zr]CH3/
each decoalesce to a new pair of Cp signals that at 128 K [B]CH3: δ ϭ 1.34/0.94}. Compound 10 separated from the
have become separated by 517 and 128 Hz, respectively (see solution as a red oil after some time. An attempt to crys-
Figure 7). From these temperature-dependent 1H NMR tallise 10 from [D6]benzene resulted in partial hydrolysis of
spectra an averaged activation barrier has been calculated the moisture-sensitive complex, and we isolated single crys-
as ∆G‡inv (128 K) ϭ 5.1 Ϯ 0.3 kcal molϪ1 [47]
.
We assume tals of the corresponding dinuclear µ-oxobis(ansa-metallo-
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642
2635

D. Hüerländer, N. Kleigrewe, G. Kehr, G. Erker, R. Fröhlich
FULL PAPER
cene) compound 11 suitable for an X-ray crystal structure sequently, the overall structural arrangement of the two
determination (see Scheme 3 and Figure 3).
metallocene subunits of 11 along the metal-oxygen-metal
vector is close to perpendicular (dihedral angle
C1ϪZr1···Zr2ϪC21 Ϫ85.8°). The conformational arrange-
ment of the strongly bent ansa-bridge is noteworthy, as it is
different in the two metallocene subunits. On both sides the
ϪCH2ϪCHϭCHϪCH2Ϫ bridge is oriented toward a lat-
eral sector of the bent metallocene wedge, and this is toward
the oxygen side in both cases, but the ansa bridge at Zr1
is bent in the direction toward the front side of the bent
metallocene, whereas at Zr2 this hydrocarbyl bridge is bent
away from the µ-oxygen atom and prefers to point toward
the narrow back side of the bent metallocene wedge.
Both the complexes 8 and 9 were used as starting mat-
erials for the generation of active homogeneous
ZieglerϪNatta catalysts. In the case of the dimethylzirco-
nium complex, activation was achieved by treatment with
B(C6F5)3 in a close to equimolar ratio (the active species
probably being 10, see Scheme 3).[53] The ansa-metallocene
dichloride 8 was activated by treatment with a large excess
Scheme 3
of methylalumoxane in toluene solution (Al/Zr
Ͼ
1000).[1,54] Both systems turned out to be excellent ethylene
polymerization catalysts (see Table 1). They also polymer-
ized propene at room temperature, although not with high
activities (a ϭ 38). The obtained polypropylene was atactic.
We had previously shown that Cp-bound alkenyl groups
can undergo a CϪC coupling reaction with metal-coordin-
ated butadiene ligands at the Group 4 metallocene frame-
works.[22] The formation of 14 from 12 via 13 is a typical ex-
ample.
Figure 3. A projection of the molecular structure of the µ-oxobis-
˚
(ansa-metallocene) complex 11; selected bond lengths [A] and
angles [°]: Zr1ϪO 1.951(2), Zr1ϪC1 2.294(3), Zr2ϪO1 1.954(2),
Zr2ϪC21 2.291(3), C6ϪC7 1.509(4), C7ϪC8 1.499(4), C8ϪC9
1.312(4), C9ϪC10 1.503(4), C10ϪC11 1.502(4), C26ϪC27
1.514(4), C27ϪC28 1.483(4), C28ϪC29 1.317(4), C29ϪC30
1.489(4), C30ϪC31 1.503(4); Zr1ϪOϪZr2 170.53(9), C1ϪZr1ϪO
97.55(9),
C21ϪZr2ϪO
97.97(9),
C6ϪC7ϪC8
113.7(2),
C7ϪC8ϪC9 124.4(3), C8ϪC9ϪC10 123.8(2), C9ϪC10ϪC11
112.8(2), C26ϪC27ϪC28 114.7(3), C27ϪC28ϪC29 124.0(3),
C28ϪC29ϪC30
C6ϪC7ϪC8ϪC9
C8ϪC9ϪC10ϪC11 Ϫ88.9(3), C26ϪC27ϪC28ϪC29 Ϫ81.7(4),
C27ϪC28ϪC29ϪC30 0.2(5), C28ϪC29ϪC30ϪC31 88.8(4)
124.0(3),
84.3(3),
C29ϪC30ϪC31
C7ϪC8ϪC9ϪC10
113.6(2);
Ϫ0.9(5),
We were curious to see whether there would be any inter-
The X-ray crystal structure analysis of 11 shows the pres- action between the endocyclic cis-CϭC double bond in the
ence of two C4-ansa-metallocene subunits, bridged by a ansa-metallocene framework and a butadiene ligand at-
close to linear µ-oxobridge [angle Zr1ϪOϪZr2: 170.53(9)°]. tached at, for example, the framework of complex 8. We
Both the zirconiumϪoxygen bonds are rather short, at therefore treated complex 8 directly with 1 mol-equiv. of the
1.951(2) A (Zr1ϪO) and 1.954(2) A (Zr2ϪO), respectively. (butadiene)Mg·(THF)n reagent[55] in [D8]toluene at room
This indicates considerable µ-oxygen ligand-to-metal π- temperature. Formation of the (butadiene)metallocenes
backbonding,[51] making use of the available acceptor or- took place. NMR analysis revealed the presence of the (s-
bital at the (formally) 16-electron metal centre.[52] Con- cis- and s-trans-η4-butadiene)[Zr] complex isomers (s-cis-15;
˚
˚
Table 1. Ethylene polymerization with homogeneous ZieglerϪNatta catalysts derived from the complexes 8 and 9
Cat. precursor[a]
Activator
Al(B)/Zr ratio
T [°C]
Reaction time [min]
PE [g]
M.p. [°C]
Act.[b]
9
8
9
8
B(C6F5)3
MAO
B(C6F5)3
MAO
1.1
1000
1.1
25
25
60
60
4
12.8
43.6
25.0
37.1
128
128
129
126
2600
3660
2150
3750
10
10
10
1250
[a]
[b]
In toluene solution at 2 bar ethene pressure. Catalyst activity in kg(polymer)/mol[Zr]·h·bar(ethene).
2636
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642

Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes
FULL PAPER
18 has an electrophilic ϪB(C6F5)2 unit covalently bonded
to its ansa-metallocene framework. Future studies should
show if this can be utilized as an internal activator compon-
ent for the generation of an active single-component metal-
locene ZieglerϪNatta catalyst system.[61,62]
LnMϩ cations can sometimes be generated by treatment
of the respective metal halide complexes (e.g., LnMϪCl)
with alkali metal cations in combination with anions of low
nucleophilicity.[63] An interesting alternative reaction,
namely Liϩ addition, was observed in one case starting
from 8. When we treated the ansa-metallocene complex cis-
8 with Liϩ[B(C6F5)4Ϫ] in [D8]toluene at room temperature,
the crystalline adduct 19 was obtained. Its rather interesting
structure was determined by X-ray diffraction (see Fig-
ures 4 and 5).
Scheme 4
s-trans-15, see Scheme 4) in a 4:5 ratio. The s-cis isomer is
easily identified by its dynamic NMR behaviour, due to a
rapid inversion of its five-membered σ2,π-metallacyclopen-
tene core on the NMR timescale at room temperature, be-
coming frozen at low temperature.[56] This results in the ob-
1
servation of a 1:1 pair of H NMR singlets at 298 K (δ ϭ
5.09, 4.88 ppm) that decoalesces to a set of four Cp signals
of equal intensity at 213 K in the [D8]toluene solvent (δ ϭ
5.55, 4.91, 4.78, 4.53 ppm). In contrast, the chiral (averaged
C2-symmetric) s-trans-15 isomer exhibits temperature-in-
The X-ray crystal structure analysis revealed that the Liϩ
cations of two independent molecules are (electrostatically)
coordinated to the pair of chloride ligands[64,65] at the zir-
conium center in a chelate fashion. The coordination sphere
around the lithium ion is complemented by two additional
1
variant NMR spectra showing four separate H NMR Cp
resonances (213 K: δ ϭ 4.87, 4.85, 4.53, 4.35 ppm) through-
out this temperature range. The H/13C NMR shifts of the
1
(s-cis-η4-butadiene)[Zr] complex [213 K: δ ϭ 4.76, 3.42,
Ϫ0.59 (Hmeso, Hsyn, Hanti)/112.1, 49.7 (C-2/3, C-1/4) ppm]
and its s-trans-15 isomer [213 K: δ ϭ 3.04, 3.14, 1.38 ppm
(1H)/96.7, 59.1 ppm (13C)] are characteristically different.[56]
The s-cis- and s-trans-15 complexes are stable as such in
the examined temperature range. We have so far found no
evidence of the occurrence of a CϪC coupling reaction with
the disubstituted CϭC double bond of the adjacent ansa
bridge.
The CϭC double bond in cis-8 undergoes reactions typ-
ical of olefins, however. Catalytic hydrogenation (H2, Pd/
C) cleanly yields the saturated tetramethylene-bridged ansa-
Figure 4. A view of the cis-8·Liϩ[B(C6F5)4Ϫ] adduct structure (19);
˚
selected bond lengths [A] and angles [°]: Zr1ϪCl11 2.479(1),
Zr1ϪCl21 2.487(1), Zr2ϪCl21 2.454(1), Zr2ϪCl22 2.477(1),
C11ϪC16 1.518(5), C31ϪC36 1.504(6), C16ϪC17 1.480(6),
C36ϪC37 1.517(10), C17ϪC18 1.327(5), C37ϪC38 1.436(12),
C18ϪC19 1.467(5), C38ϪC39 1.445(12), C19ϪC20 1.516(4),
C39ϪC40 1.480(8); Cl11ϪZr1ϪCl12 87.53(2), Cl21ϪZr2ϪCl22
89.50(3), C11ϪC16ϪC17 112.5(3), C31ϪC36ϪC37 115.3(4),
C16ϪC17ϪC18 126.0(4), C36ϪC37ϪC38 117.8(5), C17ϪC18Ϫ
C19 125.5(4), C37ϪC38ϪC39 116.9(6), C18ϪC19ϪC20 112.4(3),
C38ϪC39ϪC40
105.0(8);
C11ϪC16ϪC17ϪC18
Ϫ85.4(5),
C31ϪC36ϪC37ϪC38 80.7(8), C16ϪC17ϪC18ϪC19 0.4(6),
C36ϪC37ϪC38ϪC39 Ϫ0.8(7), C17ϪC18ϪC19ϪC20 87.5(5),
C37ϪC38ϪC39ϪC40 Ϫ102.7(6); Li1ϪCl11 2.376(5), Li1ϪCl12
2.385(5), Li2ϪCl21 2.379(6), Li2ϪCl22 2.420(6), Li1ϪF115
2.812(6), Li1ϪF116 1.985(5), Li2ϪF203 2.567(6), Li2ϪF202
2.045(5), Li1ϪF235 2.235(5), Li1ϪF236 2.087(5), Li2ϪF135
Scheme 5
zirconocene dichloride complex 16 (see Scheme 5). Hydro-
boration takes place equally facilely and also leaves the
2.223(6),
Li2ϪF136
2.052(5);
Cl11ϪLi1ϪCl12
92.4(2),
metallocene nucleus untouched. We have used two sterically Cl21ϪLi2ϪCl22 92.7(2), Cl11ϪLi1ϪF115 159.1(2), Cl21ϪLi2Ϫ
F203 160.8(2), Cl11ϪLi1ϪF116 101.9(2), Cl21ϪLi2ϪF202 96.9(2),
and electronically quite different boranes for this purpose.
Cl11ϪLi1ϪF235 91.6(2), Cl21ϪLi2ϪF135 86.1(2), Cl11ϪLi1Ϫ
9-BBN[57,58] adds to the endocyclic double bond in cis-8 to
F236 115.8(2), Cl21ϪLi2ϪF136 105.2(2), Cl12ϪLi1ϪF115 78.9(2),
Cl22ϪLi2ϪF203 83.4(2), Cl12ϪLi1ϪF116 105.0(2), Cl22ϪLi2Ϫ
F202 110.0(2), Cl12ϪLi1ϪF235 168.5(2), Cl22ϪLi2ϪF135
165.9(3), Cl12ϪLi1ϪF236 96.1(2), Cl22ϪLi2ϪF136 93.3(2),
F115ϪLi1ϪF116 63.1(2), F203ϪLi2ϪF202 67.2(2), F115ϪLi1Ϫ
F235 100.7(2), F203ϪLi2ϪF135 102.1(2), F115ϪLi1ϪF236
84.2(2), F203ϪLi2ϪF136 93.8(2), F116ϪLi1ϪF235 84.8(2),
F202ϪLi2ϪF135 84.1(2), F116ϪLi1ϪF236 135.9(3), F202ϪLi2Ϫ
yield the product 17. The borylated complex 18 was formed
by treatment of cis-8 with the electrophilic borane
HϪB(C6F5)2.[59,60] As expected, each of these products
now shows eight H NMR signals of the pair of monosub-
stituted Cp ligands [17: δ ϭ 6.53, 6.45 (2 H), 6.42, 6.40,
1
6.35, 6.33, 6.25 ppm]. It is interesting to note that complex F136 147.0(3), F235ϪLi1ϪF236 72.5(2), F135ϪLi2ϪF136 73.5(2)
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642 2637

D. Hüerländer, N. Kleigrewe, G. Kehr, G. Erker, R. Fröhlich
FULL PAPER
It is also noteworthy that the conformational arrange-
ment of the ϪCH2ϪCHϭCHϪCH2Ϫ ansa bridge in cis-8
and in the adduct 19 are quite different. In the former, the
CϭC double bond in the strongly bent structural subunit is
oriented toward the back side (Zr···CϭC separation ca. 4
˚
A), whereas in the latter it is found in the inverted position
(see Figure 6), which brings the CϭC π-system closer to the
electron-deficient d0-configurated Group 4 metal centre (in
˚
19 the Zr···CϭC separation is only ca. 3.5 A).
Figure 5. A projection of the chain structure of the adduct 19 in
the crystal
chelate interactions, each with a pair of ortho- and meta-
fluorine atoms of one C6F5 substituent from two different
adjacent [B(C6F5)4Ϫ] anions. This complements a distorted
octahedral coordination sphere around the alkali metal cat-
ion (see Figure 4). The octahedral geometry is, however,
markedly distorted. Of the (idealised) three 180° bonding
angles around the central (alkali) metal ion, only two are
close to linear [F135ϪLi2ϪCl22: 165.9(3)° and
Cl21ϪLi2ϪF203: 160.8(2)°; only the data of one of the
crystallographically independent units (here around Li2)
are given, those around Li1 are similar], whereas the third
is markedly smaller at 147.0(3)° (F202ϪLi2ϪF136). Most
of the remaining twelve bonding angles at the origin of the
distorted octahedron are reasonably close to the expected
90° [F202ϪLi2ϪF135: 84.1(2)°, F202ϪLi2ϪCl21: 96.9(2)°,
F135ϪLi2ϪCl21: 86.1(2)°, F136ϪLi2ϪCl22: 93.3(2)°,
Cl21ϪLi2ϪCl22: 92.7(2)°, F136ϪLi2ϪF203: 93.8(2)°,
Cl22ϪLi2ϪF203: 83.4(2)°], with the exception of the two
narrow internal o-/m-F chelate angles [F136ϪLi2ϪF135:
73.5(2)° and F202ϪLi2ϪF203: 67.2(2)°] and some second-
Figure 6. A comparison of the ansa-metallocene core conformation
as found in cis-8 (top) and the adduct 19 (bottom)
ary
deviation,
caused
by
this
chelate
effect
We conclude that olefin metathesis at the CpϪalkenyl
unit of Group 4 metallocenes can easily be carried out in-
tramolecularly, cleanly yielding the respective unsaturated
ansa-metallocenes with loss of ethene. The CϭC bond in-
side the ansa-metallocene bridge undergoes a variety of typ-
ical reactions without affecting the Group 4 metallocene
backbone. Such combinations of reactions may potentially
open up new synthetic pathways to functionalized bent
metallocene complexes that may turn out to be useful for
the development of improved catalysts for rapid and select-
ive CϪC coupling reactions and/or for use as reagents in
organic synthesis. Studies aimed at finding out about such
properties are being carried out in our laboratory.
[F136ϪLi2ϪCl21: 105.2(2)°, F202ϪLi2ϪCl22: 110.0(2)°,
F135ϪLi2ϪF203: 102.1(2)°].
The lithium chloride contact lengths in the adduct 19
˚ ˚
A (Li2ϪCl21) and 2.420(6) A
amount to 2.379(6)
(Li2ϪCl22). The LiϪF distances cover a wider range
˚
˚
[Li2ϪF202: 2.045(5) A, Li2ϪF136: 2.052(5) A, Li2ϪF135:
Ϫ
˚
˚
2.223(6) A, and Li2ϪF203: 2.567(6) A]. Each [B(C6F5)4
]
anion in the adduct 19 contains two C6F5 units that exhibit
chelate contacts to two different Liϩ cations, whereas the
remaining C6F5 pair of substituents is oriented away from
the alkali metal centres. This results in a chain-type supra-
structure of 19, depicted in Figure 5.
The electrostatic Liϩ coordination has changed the
[Zr]Cl2 geometry slightly. In comparison with the starting
material 8, the ZrϪCl bond lengths in the adduct 19 are
Experimental Section
˚
slightly longer [Zr1ϪCl11: 2.479(1) A, Zr1ϪCl12: 2.487(1)
˚
˚
˚
A, Zr2ϪCl21: 2.454(1) A, Zr2ϪCl22: 2.477(1) A; see for
General: All reactions were carried out under dry argon in Schlenk-
type glassware or in a glove-box. Solvents, including deuterated
solvents used for NMR spectroscopy, were dried and distilled prior
to use. For additional general conditions, including a list of instru-
ments used for physical characterization of the compounds, see
˚
comparison: cis-8 ZrϪCl1: 2.437(1) A, ZrϪCl2: 2.455(1)
˚
A]. Consequently, the Cl11ϪZr1ϪCl12 angle in 19 is mark-
edly smaller [87.53(2)°; Cl21ϪZr2ϪCl22: 89.50(3)] than in
cis-8 [Cl1ϪZr2ϪCl2: 95.95(2)°].
2638
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642

Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes
FULL PAPER
ref.[41b] or ref.[66] NMR assignments were usually secured by carry-
ing out a variety of 2D NMR experiments.[67] The starting mat-
over a temperature range of 253 to 128 K (Figure 7). The AAЈBBЈ
spin system of the Cp protons at high temperature changed to an
erials 3 and 7 were prepared according to literature procedures.[8,22] ABCD spin system at low temperature. The activation energies
were estimated as ∆Gi϶nv [Tc: 153 K; ∆ν (128 K): 517 Hz] ϭ
Preparation of [Dec-5-ene-1,10-diylbis(η5-cyclopentadienyl)]zircon-
5.22 kcal·molϪ1 for one group of protons and ∆G϶inv [Tc: 138 K; ∆ν
ium Dichloride (trans-4): A solution containing [Cl2(PCy3)2Ruϭ
(128 K) ϭ 128 Hz] ϭ 5.07 kcal·molϪ1 for the other. The average
CHPh] (45.3 mg, 0.06 mmol, 10 mol %) in 400 mL of dichlorome-
activation energy was calculated as ∆G϶inv ϭ 5.1 Ϯ 0.3 kcal·molϪ1
.
thane was brought to reflux temperature in a three-necked flask,
equipped with stirrer, reflux condenser and a septum. Over 6 h a
solution of bis[η5-(5-hexen-1-yl)cyclopentadienyl]ZrCl2 (3, 250 mg,
0.55 mmol) in 100 mL of dichloromethane was added by syringe
pump. The mixture was heated under reflux for an additional 3 h,
and then cooled to room temperature and filtered. Solvent was
removed in vacuo, and the residue was washed with pentane (2 ϫ
20 mL). Fractional crystallization from toluene (10 mL) gave
58.9 mg (25%) of trans-4 as a white solid, m.p. 162 °C. IR (KBr):
ν˜ ϭ 3103 w, 2929 m, 2856 w, 2387 w, 1497 w, 1263 m, 1102 s, 1035 s,
969 w, 841 w, 828 s, 825 vs cmϪ1
.
1H NMR ([D6]benzene,
599.9 MHz, 298 K): δ ϭ 5.97 (m, 4 H, 3,4-H), 5.73 (m, 4 H, 2,5-
H), 5.25 (m, 2 H, 10-H), 2.52 (m, 4 H, 6-H), 2.01 (m, 4 H, 9-
H), 1.30 (m, 4 H, 8-H), 1.22 (m, 4 H, 7-H) ppm. 13C{1H} NMR
([D6]benzene, 150.8 MHz, 298 K): δ ϭ 139.3 (C, C-1), 131.5 (CH,
C-10), 115.1 (CH, C-3,4), 111.0 (CH, C-2,5), 31.9 (CH2, C-9), 29.3
(CH2, C-6), 28.5 (CH2, C-8), 26.4 (CH2, C-7) ppm. C20H26Cl2Zr
(428.5): calcd. C 56.05, H 6.12; found C 56.35, H 6.63.
Figure 7. Dynamic 1H NMR spectrum of cis-8 (in CDFCl2/
CDF2Cl)
X-ray Crystal Structure Analysis of trans-4: Single crystals were ob-
tained from [D6]benzene at ambient temperature. C20H26Cl2Zr,
M ϭ 428.53, yellow crystal, 0.30 ϫ 0.04 ϫ 0.03 mm, a ϭ 6.581(1),
3
˚
˚
b ϭ 20.480(1), c ϭ 14.451(1) A, β ϭ 97.47(1)°, V ϭ 1931.2(3) A ,
ρ
X-ray Crystal Structure Analysis of cis-8: Single crystals of the
ansa-metallocene were obtained from [D6]benzene at room temper-
ature. C14H14Cl2Zr, M ϭ 344.37, light yellow crystal, 0.40 ϫ 0.20
calcd. ϭ 1.474 g cmϪ3, µ ϭ 8.43 cmϪ1, empirical absorption correc-
tion by SORTAV (0.786 Յ T Յ 0.975), Z ϭ 4, monoclinic, space
˚
group P21/c (no. 14), λ ϭ 0.71073 A, T ϭ 198 K, ω and ϕ scans,
˚
ϫ 0.10 mm, a ϭ 7.798(1), b ϭ 12.887(1), c ϭ 13.044(1) A, V ϭ
5920 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] ϭ 0.59 AϪ1, 3401
3
˚
1310.8(2) A , ρcalcd. ϭ 1.745 g cmϪ3, µ ϭ 12.19 cmϪ1, empirical
˚
independent (Rint ϭ 0.066) and 2048 observed reflections [I Ն 2
absorption correction by SORTAV (0.641 Յ T Յ 0.888), Z ϭ 4,
σ(I)], 209 refined parameters, R ϭ 0.094, wR2 ϭ 0.165, max. (min.)
˚
orthorhombic, space group P212121 (no. 19), λ ϭ 0.71073 A, T ϭ
residual electron density 1.46 (Ϫ1.19) e AϪ3, weakly diffracting
˚
198 K, ω and ϕ scans, 10,955 reflections collected (Ϯh, Ϯk, Ϯl),
crystal due to its shape; therefore the accuracy of the resulting data
is poor, hydrogen atoms calculated and refined as riding atoms.
[(sinθ)/λ] ϭ 0.67 AϪ1, 3159 independent (Rint ϭ 0.037) and 3025
˚
observed reflections [I Ն 2 σ(I)], 156 refined parameters, R ϭ 0.020,
wR2 ϭ 0.043, max. (min.) residual electron density 0.29 (Ϫ0.40) e
Synthesis of [But-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zirconium
Dichloride (cis-8): Analogously to the procedure described above,
bis[η5-(2-propen-1-yl)cyclopentadienyl]ZrCl2 (7, 1.60 g, 4.30 mmol)
was metathesized by treatment with [Cl2(PCy3)2RuϭCHPh]
(248 mg, 0.30 mmol, 7 mol %) in a total of 500 mL of dichlorome-
thane under high-dilution conditions. The mixture was heated un-
der reflux for an additional 6 h, cooled to room temperature and
filtered. The volume of the resulting solution was reduced to 20
mL in vacuo. Crystallization at Ϫ30 °C overnight gave a crystalline
precipitate that was washed with pentane (15 mL) and dried in
vacuo to give 740 mg (50%) of cis-8 as a microcrystalline solid,
m.p. 182 °C. IR (KBr): ν˜ ϭ 3117 w, 2968 w, 2922 w, 2848 w, 2373 w,
1487 w, 1447 m, 1430 w, 1269 m, 1098 w, 1046 s, 960 w, 903 m,
˚
A
Ϫ3, refined as racemic twin, Flack parameter 0.17(3), hydrogen
atoms calculated and refined as riding atoms.
[But-2-ene-1,4-diylbis(η5-cyclopentadienyl)]dimethylzirconium (9):
[But-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zirconium dichloride
(8, 50 mg, 0.15 mmol) and methyllithium (6.4 mg, 0.3 mmol) were
suspended in 2 mL of toluene, precooled to Ϫ78 °C. The suspen-
sion was allowed to warm up to room temperature and stirred over-
night. The reaction mixture was filtered through Celite. After re-
moval of the solvent in vacuo, product 9 was isolated as a brown
solid (yield: 32 mg, 72%), m.p. 48 °C. IR (KBr): ν˜ ϭ 3115 w,
2961 m, 2926 w, 2869 w, 1458 w, 1412 w, 1269 vs, 1097 s, 1028 s, 965
w, 867 w, 793 vs, 729 m cmϪ1. 1H NMR ([D6]benzene, 599.9 MHz,
298 K): δ ϭ 6.01, 5.62 (each m, each 4 H, Cp-H), 5.58 (m, 2 H, 7-
829 s, 817 vs, 795 s cmϪ1 1H NMR ([D6]benzene, 599.9 MHz,
.
298 K): δ ϭ 6.02 (m, 4 H, 2,5-H), 6.00 (m, 4 H, 3,4-H), 5.61 (m, 2
H, 7-H), 2.74 (m, 4 H, 6-H) ppm. 1H NMR (CDFCl2/CDF2Cl,
599.9 MHz): δ (253 K) ϭ 6.66, 6.32 (each m, each 4 H, 2,5-H, 3,4-
H), 6.31 (m, 2 H, 7-H), 3.35 (m, 4 H, 6-H); δ (128 K) ϭ 6.83/6.61,
6.74/5.87 (each br., each 2 H, 2,5-H, 3,4-H), 6.33 (br., 2 H, 7-H),
3.29, 3.25 (each br., each 2 H, 6-H) ppm. 13C{1H} NMR ([D6]ben-
H), 2.66 (m, 4 H, 6-H), Ϫ0.05 (s, 6 H, CH3) ppm. 13C{GATED}
1
NMR ([D6]benzene, 150.8 MHz, 298 K): δ ϭ 129.6 (dm, JCH
ϭ
1
158 Hz, C-7), 120.8 (s, C-1), 111.9 (d, JCH ϭ 172 Hz, Cp), 110.2
1
1
(d, JCH ϭ 171 Hz, Cp), 31.0 (q, JCH ϭ 117 Hz, CH3), 24.4 (t,
1JCH ϭ 128 Hz, C-6) ppm. C16H20Zr (303.56): calcd. C 63.31, H
6.64; found C 61.64, H 6.72. Single crystals of the partial hydrolysis
product 11, suitable for X-ray diffraction, were obtained from a
concentrated [D6]benzene solution of 9.
1
zene, 150.8 MHz, 298 K): δ ϭ 129.7 (CH, JCH ϭ 145 Hz, C-7),
1
121.2 (C, C-1), 119.3 (CH, JCH ϭ 176 Hz, C-2,5), 115.3 (CH,
1JCH ϭ 175 Hz, C-3,4), 24.8 (CH2, JCH ϭ 129 Hz, C-6) ppm.
1
C14H14Cl2Zr (344.4): calcd. C 48.83, H 4.10; found C 48.70, H
4.84. The dynamic behaviour of cis-8 was monitored by H NMR
X-ray Crystal Structure Analysis of 11: C30H34OZr2, M ϭ 593.01,
colourless crystal 0.60 ϫ 0.20 ϫ 0.08 mm, a ϭ 8.218(1), b ϭ
1
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642
2639

D. Hüerländer, N. Kleigrewe, G. Kehr, G. Erker, R. Fröhlich
FULL PAPER
3
˚
˚
10.985(1), c ϭ 27.805(1) A, β ϭ 94.07(1)°, V ϭ 2503.8(4) A ,
CH, Cp), 96.0 o. 97.6 (CH, Cp), 49.7 (butadiene-CH2), 25.3, 25.0
(each CH2, C-6) ppm. s-trans-15: 1H NMR ([D8]toluene,
599.9 MHz): δ (298 K) ϭ 5.81 (m, 2 H, 7-H), 4.96, 4.93, 4.57, 4.39
(each m, each 2 H, Cp-H), 3.02 (m, 2 H, Hsyn), 2.99 (m, 4 H, 6-
H), 2.97 (m, 2 H, Hmeso), 1.24 (m, 2 H, Hanti); δ (213 K) ϭ 5.79
ρ
calcd. ϭ 1.573 g cmϪ3, µ ϭ 8.53 cmϪ1, empirical absorption correc-
tion by SORTAV (0.629 Յ T Յ 0.935), Z ϭ 4, monoclinic, space
group P21/c (no. 14), λ ϭ 0.71073 A, T ϭ 198 K, ω and ϕ scans,
17976 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] ϭ 0.66 A
˚
Ϫ1
˚
,
5886 independent (Rint ϭ 0.048) and 4599 observed reflections [I (m, 2 H, 7-H), 4.87, 4.85, 4.53, 4.35 (br) (each m, each 2 H, Cp-
Ն 2 σ(I)], 300 refined parameters, R ϭ 0.035, wR2 ϭ 0.061, max.
H), 3.14 (m, 2 H, Hsyn), 3.04 (m, 2 H, Hmeso), 2.97 (m, 4 H, 6-H),
1.38 (m, 2 H, Hanti) ppm. 13C{1H} NMR ([D8]toluene, 150.8 MHz,
298 K): δ ϭ 130.2 (CH, 1JCH ϭ 157 Hz, C-7), 112.1 (C, C-1), 104.4
(min.) residual electron density 0.39 (Ϫ0.52) e AϪ3, hydrogen atoms
˚
calculated and refined as riding atoms.
1
1
(CH, JCH ϭ 170 Hz, C-Cp), 101.7 (CH, JCH ϭ 172 Hz, C-Cp),
98.0 (CH, 1JCH ϭ 174 Hz, C-Cp), 96.1 (CH, 1JCH ϭ 149 Hz, buta-
Ethene Polymerization Reactions: These were carried out in a 1-L
Büchi glass autoclave, charged with 300 mL of toluene. In the cases
in which the ansa-metallocene dichloride cis-8 was used as a pre-
cursor, methylalumoxane (MAO) in toluene (10.5%, 20 mL,
9.05 mmol) was added. In the case of the dimethylmetallocene/
B(C6F5)3 catalysts, triisobutylaluminium (0.5 mL) was added in-
stead as a water scavenger. The autoclave was brought to the de-
sired temperature and the solution was then saturated with ethene
at a 2 bar pressure with stirring (800 rpm) for ca. 40 min. Either cis-
8 or the 9/B(C6F5)3 mixture (see Table 1 for details) was injected. To
end the polymerization reaction, the ethene addition was termin-
ated, excess monomer was allowed to vent, and the mixture was
quenched by injection of 40 mL of a solution of dilute aqueous
HCl/methanol (1:1). After 20 min of stirring, 100 mL of H2O was
added. The precipitated polyethylene was collected by filtration,
and washed with 50 mL of 2  aqueous HCl and then with water.
The polymer was dried in vacuo for 24 h. The observed ethene
polymerization activities of the homogeneous ZieglerϪNatta cata-
lyst derived from 8 or 9 (Table 1) are in a range similar to those
obtained with related unbridged systems under similar conditions
(e.g., 7/MAO: a ഠ 2400 kg PE/mol [Zr]·h·bar at 25 °C). Propene
polymerization reactions were carried out analogously (2 bar pro-
pene pressure). The 9/B(C6F5)3 system gave atactic polypropylene
(stereochemical analysis by 13C NMR spectroscopy) with a catalyst
activity of a ϭ 38 kg PP/mol [Zr]·h·bar at 25 °C. The 8/MAO cata-
lyst system produced atactic polypropylene at 25 °C with a ϭ 38
(Al/Zr ϭ 800) at 60 °C with a ϭ 40 (Al/Zr ϭ 1050).
1
1
diene-CH), 95.9 (CH, JCH ϭ 175 Hz, C-Cp), 59.5 (CH2, JCH
ϭ
1
1
157, JCH ϭ 146 Hz, butadiene-CH2), 25.5 (CH2, JCH ϭ 125 Hz,
C-6); δ (213) ϭ 129.8 (CH, C-7), 111.1 (C, C-1), 104.0, 101.1(4)
(CH, Cp), 97.6 o. 96.0 (CH, Cp), 95.7 (CH, butadiene-CH), 95.3
(CH, Cp), 59.1 (CH2, butadiene-CH2), 24.9 (CH2, C-6) ppm.
Catalytic Hydrogenation of cis-8. Preparation of 16: Complex cis-
8 (77 mg, 0.22 mmol) was dissolved in dichloromethane (20 mL).
Heterogeneous Pd(C) catalyst (10% palladium, 80 mg) was added.
Hydrogen was passed through the solution through a frit at 1 bar
with stirring for 2 h. The catalyst was removed by filtration and the
solvent was evaporated in vacuo to yield 43 mg (56%) of the ansa-
metallocene 16. 1H NMR ([D2]dichloromethane, 599.9 MHz,
298 K): δ ϭ 6.40 (m, 4 H, 2,5-H), 6.38 (m, 4 H, 3,4-H), 2.84 (br.
m, 4 H, 6-H), 1.90 (m, 4 H, 7-H) ppm. 13C{1H} NMR ([D2]dichlor-
omethane, 150.8 MHz, 298 K): δ ϭ 128.1 (C, C-1), 118.5 (CH, C-
3,4), 117.6 (CH, C-2,5), 27.5 (CH2, C-6), 26.1 (CH2, C-7) ppm.
Treatment of cis-8 with 9-BBN. Preparation of 17: A mixture of
[but-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zirconium dichloride (8,
50 mg, 0.15 mmol) and 9-borabicyclo[3.3.1]nonane (17.7 mg,
0.15 mmol) was dissolved in 2 mL of dichloromethane at room
temperature. The solution was stirred for 12 h and then concen-
trated to dryness in vacuo. The product (67.1 mg, 96%) was isolated
as a white solid, m.p. 170 °C. IR (KBr): ν˜ ϭ 3094 w, 2911 m,
2837 m, 2362 w, 1492 w, 1452 m, 1355 w, 1309 w, 1195 w, 1012 m,
1
880 w, 817 vs cmϪ1. H NMR ([D2]dichloromethane, 599.9 MHz,
298 K): δ ϭ 6.53, 6.33 (each m, each 1 H, 2,5-H), 6.45, 6.25 (each
m, each 1 H, 3,4-H), 6.45, 6.35 (each m, each 1 H, 2Ј,5Ј-H), 6.42,
6.40 (each m, each 1 H, 3Ј,4Ј-H), 3.03 (ABM, 2J ϭ 16.1, 3J ϭ
Preparation of (Butadiene)metallocene Complexes s-cis-15 and s-
trans-15: Samples of [but-2-ene-1,4-diylbis(η5-cyclopentadienyl)]-
zirconium dichloride (8, 80 mg, 0.23 mmol) and 2-butene-1,4-diyl-
bis(tetrahydrofuran)magnesium (95.1 mg, 0.23 mmol) were mixed
as solids and then dissolved in 3 mL of toluene. The reaction
mixture spontaneously changed colour to deep red, and a white
precipitate was formed. Because of the rapid decomposition of the
product upon filtration, all volatile components were removed in
vacuo to obtain the product 15·MgCl2(THF)n (112 mg, 85%) as a
red solid (in [D8]toluene solution at 298 K both the s-cis-15 and
2
3
2.3 Hz, 1 H, 6-H), 2.99 (ABMN, J ϭ 16.2, J ϭ 3.0, 3J ϭ 7.1 Hz,
2
3
3
1 H, 9-H), 2.89 (ABMN, J ϭ 16.2, J ϭ 2.6, J ϭ 10.9 Hz, 1 H,
2
3
9-HЈ), 2.75 (ABM, J ϭ 16.1, J ϭ 9.0 Hz, 1 H, 6-HЈ), 2.09 (m, 1
H, 8-H), 1.88 (m, 1 H, 8-HЈ), 1.94, 1.72 (each m, each 4 H, β, δ-
H), 1.93, 1.28 (each m, each 2 H, γ-H), 1.82 (m, 2 H, α-H), 1.71 (m,
1 H, 7-H) ppm. 13C{1H} NMR ([D2]dichloromethane, 150.8 MHz,
298 K): δ ϭ 129.4 (C, C-1), 128.1 (C, C-1Ј), 122.0, 115.1 (each CH,
C-2,5), 120.5, 113.6 (each CH, C-2Ј,5Ј), 120.4, 117.4 (each CH, C-
3,4), 118.4, 117.3 (each CH, C-3Ј,4Ј), 34.0, 33.9 (each CH2, C-β,
δ), 31.3 (br. CH, C-7), 30.7 (br. CH, C-α), 27.8 (CH2, C-9), 27.4
(CH2, C-6), 26.4 (CH2, C-8), 23.5 (CH2, C-γ) ppm. 11B{1H} NMR
([D6]benzene, 64.2 MHz, 298 K): δ ϭ 87 (ν1/2 ϭ 329 Hz) ppm.
C22H29BCl2Zr (466.41): calcd. C 56.65, H 6.27; found C 55.72, H
6.16.
the s-trans-15 isomers were detected in
a
4:5 ratio).
(C18H20Zr)·(THF)2MgCl2 (327.58 ϩ 239.42 ϭ 567.00): calcd. C
55.08, H 6.40; found C 53.22, H 6.43. IR (KBr): ν˜ ϭ 2962 w,
2915 m, 2849 m, 1635 w, 1449 m, 1262 m, 1042 s, 797 s, 729 m
cmϪ1. s-cis-15: 1H NMR ([D8]toluene, 599.9 MHz, 298 K): δ
(298 K) ϭ 5.81 (m, 2 H, 7-H), 5.09 (br., 4 H, Cp-H), 4.88 (br. m,
4 H, Cp-H), 4.73 (m, 2 H, Hmeso), 2.91 (m, 4 H, 6-H), 1.24 (br., 4
H, Hsyn, Hanti) ppm; δ (213 K) ϭ 5.89, 5.75 (each m, each 1 H, 7-
H), 5.55, 4.91, 4.53 (each br., each 2 H, Cp-H), 4.78 (m, 2 H, Cp-
Treatment of cis-8 with H-B(C6F5)2. Preparation of 18: A mixture
of [but-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zirconium dichloride
H), 4.76 (m, 2 H, Hmeso), 3.42 (m, 2 H, Hsyn), 2.97 (m, 2 H, 6-H), (8, 50 mg, 0.15 mmol) and bis(pentafluorophenyl)borane (50.2 mg,
2.81 (m, 2 H, 6-H), Ϫ0.59 (m, 2 H, Hanti) ppm. 13C{1H} NMR 0.145 mmol) was dissolved in 2 mL of dichloromethane at room
([D8]toluene, 150.8 MHz): δ (298 K) ϭ 130.2 (CH, 1JCH ϭ 157 Hz, temperature. The solution was stirred for 1 h. Solvent was removed
1
C-7), 118.6 (C, C-1), 112.8 (CH, JCH ϭ 157 Hz, butadiene-CH),
in vacuo to yield 90.3 mg (90%) of the product as a light brown
1
1
100.9 (CH, JCH ϭ 173 Hz, Cp), 25.8 (CH2, JCH ϭ 121 Hz, C-6) solid, m.p. 238 °C. IR (KBr): ν˜ ϭ 3103 w, 2934 m, 2861 m, 1648 m,
ppm; δ (213 K) ϭ 130.5, 129.4 (each CH, C-7), 121.5, 115.1 (each
C, C-1), 112.1 (CH, butadiene-CH), 107.9, 101.1, 101.1(4) (each
1520 s, 1467 vs, 1386 m, 1316 m, 1288 w, 1094 m, 974 s, 813 s cmϪ1
.
1H NMR ([D2]dichloromethane, 599.9 MHz, 298 K): δ ϭ 6.56, 6.43
2640
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642

Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes
FULL PAPER
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(each m, each 1 H, 2,5-H), 6.49, 6.38 (each m, each 1 H, 3Ј,4Ј-H),
6.48, 6.47 (each m, each 1 H, 2Ј,5Ј-H), 6.40, 6.28 (each m, each 1
2
3
3
H, 3,4-H), 3.12 (ABMN, J ϭ 16.8, J ϭ 2.7, J ϭ 10.5 Hz, 1 H,
2
or
9-H), 3.05 (d,
3J ϭ 15.9 Hz, 1 H, 6-H), 2.92 (ABMN, 2J ϭ
3
3
16.8, J ϭ 2.8, J ϭ 7.7 Hz, 1 H, 9-HЈ), 2.85 (m, 1 H, 6-HЈ), 2.56
(m, 1 H, 7-H), 2.16 (m, 1 H, 8-H), 1.96 (m, 1 H, 8-HЈ) ppm.
13C{1H} NMR ([D2]dichloromethane, 150.8 MHz, 298 K): δ ϭ
148.3 [dm, 1J ϭ 247.2 Hz, B(C6F5)2], 139.4 [dm, 1J ϭ 253.0 Hz,
B(C6F5)2], 145.0 (dm, 1J ϭ 265.0 Hz, B(C6F5)2], 128.4 (C, C-1),
128.3 (C, C-1Ј), 124.5, 117.9 (each CH, C-2,5), 121.5, 121.2 (CH,
C-2Ј,5Ј), 120.4, 114.6 (each CH, C-3Ј,4Ј), 119.4, 118.6 (each CH,
C-3,4), 115.0 [br., B(C6F5)2], 30.2 (CH2, C-9), 29.9 (CH2, C-6), 27.5
(CH2, C-8), (C-7 not observed) ppm. 11B{1H} NMR ([D6]benzene,
64.2 MHz, 298 K): δ ϭ 76 (ν1/2 ϭ 340 Hz) ppm. 19F NMR
([D6]benzene, 563.6 MHz, 298 K): δ ϭ Ϫ127.3 (br. m, 4 F, o-C6F5),
Ϫ146.2 (br. m, 2 F, p-C6F5), Ϫ159,4 (br. m, 4 F, m-C6F5) ppm.
C26H15BCl2F10Zr (690.33): calcd. C 45.24, H 2.19; found C 45.02,
H 2.42.
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ˇ
´ˇ
´
ˇ
ˇ
ˇ
´
ˇ
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Adduct Formation between cis-8 and Li؉[B(C6F5)4Ϫ]. Generation of
19: In an NMR experiment, cis-8 (23 mg, 0.07 mmol) was mixed
with Liϩ[B(C6F5)4Ϫ] (46 mg, 0.07 mmol), and [D8]toluene (1.0 mL)
was then added. NMR spectra of the mixture were not distingu-
ished from those of the single components, but the coordination
product 19 crystallised from the mixture after ca. 1 d at ambient
temperature to allow an X-ray crystal structure analysis.
X-ray
Crystal
Structure
Determination
of
19:
C14H14Cl2Zr·LiBC24F20, M ϭ 1030.36, colourless crystal, 0.50 ϫ
0.40 ϫ 0.15 mm, a ϭ 13.8212(1), b ϭ 14.7217(1), c ϭ 18.2205(2)
˚
A, α ϭ 88.406(1), β ϭ 77.278(1), γ ϭ 89.484(1)°, V ϭ 3614.92(5)
3
A , ρcalcd. ϭ 1.893 g cmϪ3, µ ϭ 5.88 cmϪ1, empirical absorption
˚
correction by SORTAV (0.758 Յ T Յ 0.917), Z ϭ 4, triclinic, space
˚
¯
group P1 (no. 2), λ ϭ 0.71073 A, T ϭ 198 K, ω and ϕ scans, 26503
reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] ϭ 0.67 AϪ1, 17598
˚
independent (Rint ϭ 0.025) and 14617 observed reflections [I Ն 2
σ(I)], 1135 refined parameters, R ϭ 0.043, wR2 ϭ 0.105, max.
(min.) residual electron density 1.24 (Ϫ1.44) e AϪ3, hydrogen atoms
˚
[22]
[23]
[24]
[25]
calculated and refined as riding atoms.
Data sets were collected with a Nonius KappaCCD diffractometer,
equipped with a Nonius FR591 rotating anode generator. Pro-
grams used: data collection COLLECT[68], data reduction Denzo-
SMN[69], absorption correction SORTAV[70], structure solution
SHELXS-97[71], structure refinement SHELXL-97[72], graphics
SCHAKAL[73]. CCDC-180478 to -180481 contain the supplement-
ary crystallographic data for this paper. These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html or from
the Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK [Fax: (internat.) ϩ 44-1223/336-033; E-
mail: deposit@ccdc.cam.ac.uk].
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[32]
Supporting Information Available: 2D NMR spectroscopic data of
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also the footnote on the first page of this article).
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[35]
Acknowledgments
Financial support from the Fonds der Chemischen Industrie (and
the BMBF) and the Deutsche Forschungsgemeinschaft is grate-
fully acknowledged.
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Received March 26, 2002
[I02157]
2642
Eur. J. Inorg. Chem. 2002, 2633Ϫ2642