Titanium and zirconium bent-sandwich complexes with the new [2-(diisopropylamino)ethyl]cyclopentadienyl ligand: Catalysts for the polymerization of ethylene and the dehydrocoupling of phenylsilane

Article abstract of DOI:10.1021/om960233s

Titanium(IV) and zirconium(IV) bent-sandwich complexes containing the new donor substituted [2-(diisopropylamino)ethyl]cyclopentadienyl (Cp^N) ligand are described. Cp^NH (1; C₅H₅CH₂CH₂NⁱPr ₂) is prepared from sodium cyclopentadienide and 2-chloro-1-(diisopropylamino)ethane. The highly moisture-sensitive metallocene dichlorides Cp₂^NTiCl₂ (2) and Cp₂^NZrCl₂ (3) are synthesized by reaction of Cp^NLi with TiCl₄ and ZrCl₄, respectively. In combination with the cocatalyst methylaluminoxane (MAO) they are precursors for ethylene polymerization catalysts. Compounds 2 and 3 react with 2 equiv of HCl with protonation of the amino groups to give the air- and moisture-stable metallocene dichloride dihydrochlorides Cp₂^NTiCl₂·2HCl (4) and Cp₂^NZrCl₂·2HCl (5), which also are found to be precatalysts for the polymerization of ethylene. The dimethyl compounds Cp₂^NTiMe₂ (6) and Cp₂^NZrMe₂ (7) can be obtained by reaction of 2 and 3 with 2 equiv of methyllithium. The dibenzyl complexes Cp₂^NTiBz₂ (8) and Cp₂^NZrBz₂ (9) are formed analogously with a stoichiometric amount of benzylmagnesium bromide. The diphenoxy complex Cp₂^NTi( OPh)₂ (10) is synthesized by reaction of 2 with 2 equiv of lithium phenoxide. The dialkyl compounds 6-8 and the diphenoxy compound 10 show a remarkable activity in the catalytic dehydrocoupling of phenylsilane. Zr(NMe₂)₄ reacts with 2 equiv of Cp^NH (1) to give the zirconocene derivative Cp₂^NZr(NMe₂)₂ (11) in quantitative yield. The structure of 2 has been determined by a single-crystal X-ray diffraction study. The effects of the (dialkylamino)- and (dialkylammonio)-ethyl substituents in metallocene-type compounds of titanium and zirconium are described.

Full text of DOI:10.1021/om960233s

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Organometallics 1996, 15, 4153-4161
4153
Tita n iu m a n d Zir con iu m Ben t-Sa n d w ich Com p lexes w ith
th e New [2-(Diisop r op yla m in o)eth yl]cyclop en ta d ien yl
Liga n d : Ca ta lysts for th e P olym er iza tion of Eth ylen e
a n d th e Deh yd r ocou p lin g of P h en ylsila n e
Peter J utzi,* Thomas Redeker, Beate Neumann, and Hans-Georg Stammler
Fakulta¨t fu¨r Chemie der Universita¨t Bielefeld, Universita¨tsstrasse 25,
D-33615 Bielefeld, Germany
Received March 27, 1996X
Titanium(IV) and zirconium(IV) bent-sandwich complexes containing the new donor
substituted [2-(diisopropylamino)ethyl]cyclopentadienyl (CpN) ligand are described. CpNH
(1; C5H5CH2CH2NiPr2) is prepared from sodium cyclopentadienide and 2-chloro-1-(diisopro-
pylamino)ethane. The highly moisture-sensitive metallocene dichlorides CpN2TiCl2 (2) and
CpN2ZrCl2 (3) are synthesized by reaction of CpNLi with TiCl4 and ZrCl4, respectively. In
combination with the cocatalyst methylaluminoxane (MAO) they are precursors for ethylene
polymerization catalysts. Compounds 2 and 3 react with 2 equiv of HCl with protonation of
the amino groups to give the air- and moisture-stable metallocene dichloride dihydrochlorides
CpN2TiCl2‚2HCl (4) and CpN2ZrCl2‚2HCl (5), which also are found to be precatalysts for the
polymerization of ethylene. The dimethyl compounds CpN2TiMe2 (6) and CpN2ZrMe2 (7)
can be obtained by reaction of 2 and 3 with 2 equiv of methyllithium. The dibenzyl complexes
CpN2TiBz2 (8) and CpN2ZrBz2 (9) are formed analogously with a stoichiometric amount of
benzylmagnesium bromide. The diphenoxy complex CpN2Ti(OPh)2 (10) is synthesized by
reaction of 2 with 2 equiv of lithium phenoxide. The dialkyl compounds 6-8 and the
diphenoxy compound 10 show a remarkable activity in the catalytic dehydrocoupling of
phenylsilane. Zr(NMe2)4 reacts with 2 equiv of CpNH (1) to give the zirconocene derivative
CpN2Zr(NMe2)2 (11) in quantitative yield. The structure of 2 has been determined by a single-
crystal X-ray diffraction study. The effects of the (dialkylamino)- and (dialkylammonio)-
ethyl substituents in metallocene-type compounds of titanium and zirconium are described.
In tr od u ction
lytic processes. Furthermore, enhanced water solubility
may be achieved, for example, by quaternization of an
amino group in the side chain.7,8a,11 Another important
feature of the additional donor function is the possibility
of fixing catalytically active complexes on surfaces.9
Very recently, we have introduced cyclopentadienyl
ligands with an additional dimethylamino functionality
into the chemistry of s-, p-, d-, and f-block elements.1-8
Most of this work was concentrated on compounds with
[(dimethylamino)ethyl]cyclopentadienyl ligands.
Cyclopentadienyl systems with an additional donor
function in the side chain are attracting increased
interest in the chemistry of metal complexes.1-19 Under
appropriate conditions, the donor atom can coordinate
reversibly to the metal center and temporarily block a
vacant coordination site. As a result, it seems possible
to stabilize highly reactive intermediates in catalytic
reactions and to increase their lifetimes. This could
effect the activity of such systems in a variety of cata-
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X Abstract published in Advance ACS Abstracts, August 1, 1996.
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S0276-7333(96)00233-6 CCC: $12 00 © 1996 American Chemical Society

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4154 Organometallics, Vol. 15, No. 20, 1996
J utzi et al.
Ch a r t 1
Sch em e 1
In this work, we describe the synthesis of titanium
and zirconium bent-sandwich complexes with the new
(diisopropylamino)ethyl-functionalized cyclopentadienyl
ligand CpN (tC5H4CH2CH2NiPr2, Chart 1). Special
emphasis is put on the characterization of these com-
plexes and on their suitability as precursors in homo-
geneous Ziegler-Natta ethylene polymerization reac-
tions20 and in the dehydrocoupling of phenylsilane.21
Sch em e 2
Resu lts
I. Syn th eses. The new cyclopentadiene C5H5CH2-
CH2NiPr2 (tCpNH; 1), with a (diisopropylamino)ethyl
side chain, is synthesized from sodium cyclopentadien-
ide and 2-chloro-1-(diisopropylamino)ethane in THF as
solvent. After aqueous workup, the monosubstituted
cyclopentadiene 1 is obtained in good yield after distil-
lation in the form of a colorless liquid as a mixture of
two isomers with the side chain in a vinylic position.
CpNH (1) dimerizes at room temperature by a cycload-
dition process and must therefore be stored at low
temperatures; the dimer can be cracked at 180 °C to
give the monomer.
Treating a solution of TiCl4 in toluene with a suspen-
sion of 2 equiv of CpNLi in ether leads to the formation
of the desired metallocene dichloride (C5H4CH2CH2Ni-
Pr2)2TiCl2 (2), which can be isolated as a red solid in
49% yield. The zirconium complex (C5H4CH2CH2Ni-
Pr2)2ZrCl2 (3) can be synthesized in 57% yield in the
form of a pale yellow solid by an analogous procedure.
Crystallization of 2 and 3 from toluene affords deep red
and colorless crystals, respectively.
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Complexes 2 and 3 are moderately soluble in polar
solvents such as diethyl ether and THF and are re-
markably soluble in nonpolar solvents such as benzene
and toluene. Over several days an amorphous solid
precipitates from a concentrated benzene solution. This
solid can only scarcely be redissolved. It is a coordina-
tion polymer and not a decomposition product.22 How-
ever, in dilute solution a complete characterization of
CpN2MCl2 is possible. 1H NMR spectroscopy indicates
the presence of monomeric species (vide infra). Fur-
thermore, crystals of monomeric 2 can be obtained from
a dilute toluene solution (see section III, X-ray Crystal
Structure Analysis of 2). In contrast to the nonfunc-
tionalized, parent metallocene dichlorides23 Cp2TiCl2
and Cp2ZrCl2, the complexes 2 and 3 are extremely
moisture-sensitive. Decomposition takes place in protic
solvents such as methanol and water, and the N-
protonated cyclopentadiene [C5H5CH2CH2N(H)iPr2]+[Cl]-
is formed.
Compound 2 reacts with 2 equiv of hydrogen chloride
in methanolic solution with protonation of the amino
(22) This could be proved by the reaction of the solid with methanolic
HCl. The polymer structure is destroyed, and the protonation of the
N-functions results in the formation of the monomer metallocene
dichlorides dihydrochlorides CpN2MCl2‚2HCl in quantitative yields.
(23) Wilkinson, G.; Birmingham, J . M. J . Am. Chem. Soc. 1954, 76,
4281.

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Ti and Zr Bent-Sandwich Complexes
Organometallics, Vol. 15, No. 20, 1996 4155
Sch em e 3
2 equiv of methane and the intermediate formation of
the metallocene dichlorides 2 and 3, the protonation of
the N-functions in the side chain of the CpN ligand leads
to the formation of the metallocene dichloride dihydro-
chlorides 4 and 5. No decomposition products are
observed.
The deep red titanium dibenzyl complex (C5H4CH2-
CH2NiPr2)2TiBz2 (8) and the analogous yellow zirconium
complex (C5H4CH2CH2NiPr2)2ZrBz2 (9) are formed in
moderate yields by the reaction of 2 and 3 with a
stoichiometric amount of benzylmagnesium bromide in
diethyl ether (Scheme 3). An alternative synthesis of
the dibenzyl compounds 8 and 9 is based on the reaction
of the metallocene dichloride dihydrochlorides 4 and 5
with 4 equiv of benzylmagnesium bromide. The isolated
compounds 8 and 9 are stable toward air at room
temperature for a short period of time. They show a
good solubility in all common aprotic organic solvents.
Complex 8 decomposes slowly in benzene solution under
an inert-gas atmosphere at room temperature over
several hours. In contrast, complex 9 is stable under
these conditions. At -30 °C, 8 can be stored in solution
for several weeks without decomposition. This phe-
nomenon is also described for the parent dibenzyl
complex Cp2TiBz2.25
groups to give the titanocene dichloride dihydrochlor-
ide [(C5H4CH2CH2N(H)iPr2)2TiCl2]2+Cl- (4) as a red,
2
amorphous solid in quantitative yield. The analogous
reaction of CpN2ZrCl2 (3) leads to the formation of
the zirconocene dichloride dihydrochloride [(C5H4CH2-
CH2N(H)iPr2)2ZrCl2]2+Cl-2 (5) as a colorless, amorphous
solid (Scheme 2). Crystallization of the dihydrochlorides
4 and 5 from acetonitrile affords deep red and colorless
crystals, respectively, which are hygroscopic. The com-
plexes 4 and 5 are excellently soluble in polar solvents
such as methanol, dimethyl sulfoxide, and acetonitrile,
but they are insoluble in nonpolar solvents. It is
remarkable that, in contrast to the metallocene dichlo-
rides 2 and 3, the dihydrochlorides 4 and 5 are stable
to air and moisture. Complex 4 is stable even in water
for several hours of exposure.
The dimethyltitanium compound (C5H4CH2CH2Ni-
Pr2)2TiMe2 (6) and the analogous zirconium species
(C5H4CH2CH2NiPr2)2ZrMe2 (7) are obtained in high
yields by the reaction of 2 and 3, respectively, with 2
equiv of methyllithium in diethyl ether.
Complexes 6 and 7 are highly moisture-sensitive,
yellow oils with a characteristic odor; they show a good
solubility in polar and nonpolar aprotic solvents such
as THF and toluene. The thermal stability of 6 is
remarkable. In contrast to the temperature- and light-
sensitive complex Cp2TiMe2,24 for which an autocata-
lytic, “catastrophic” decomposition is reported, no de-
composition is observed for 6 even after several weeks
under an inert-gas atmosphere at room temperature.
The stability of the dimethylzirconium complex 7 is
comparable to that of the titanium complex 6.
Treating a toluene solution of CpN2TiCl2 (2) with 2
equiv of lithium phenoxide leads to the formation of the
diphenoxy derivative (C5H4CH2CH2NiPr2)2Ti(OPh)2 (10)
in excellent yield (Scheme 3). As for the parent complex
Cp2Ti(OPh)2,21l,26 compound 10 can be isolated as an
air-stable yellow solid, which is excellently soluble in
aromatic organic solvents. The analogous zirconium
complex (C5H4CH2CH2NiPr2)2Zr(OPh)2 could not be
isolated.27
Refluxing a toluene solution of Zr(NMe2)4 with 2 equiv
of CpNH (1) leads to the evolution of 2 equiv of dimeth-
ylamine and to the formation of the zirconium complex
(C5H4CH2CH2NiPr2)2Zr(NMe)2 (11), which can be iso-
lated as an extremely air- and moisture-sensitive bright
yellow oil (Scheme 3). In contrast to Cp2Zr(NMe2)2,28
11 can be obtained in quantitative yield without further
purification. The solubility of 11 in nonpolar solvents
such as pentane and toluene is excellent. The analogous
titanium complex (C5H4CH2CH2NiPr2)2Ti(NMe2)2 could
not be prepared by this route.
1
The compounds 1-11 have been characterized by H
and 13C NMR and MS data and by elemental analysis.
For compound 9 a correct elemental analysis could not
be obtained; this is attributed to the presence of traces
of ZrCl4, which could not be separated completely.
II. NMR An a lyses. The NMR spectra (Table 1) of
2-11 are in agreement with metallocene-type structures
(24) (a) Clauss, K.; Bestian, H. J ustus Liebigs Ann. Chem. 1962,
654, 8. (b) Tebbe, F. N.; Parshall, G. W.; Reddy, G. S. J . Am. Chem.
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1994, 464, C17.
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1972, 654. (b) Boekel, C. P.; Teuben, J . H.; de Liefde Meijer, H. J . J .
Organomet. Chem. 1975, 102, 317. (c) Scholz, J .; Schlegel, M.; Thiele,
K.-H. Chem. Ber. 1987, 120, 1369. (d) Scholz, J .; Rehbaum, F.; Thiele,
K.-H.; Goddard, R.; Petz, P.; Kru¨ger, C. J . Organomet. Chem. 1993,
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Organometallics 1993, 12, 486.
The dimethyl compounds 6 and 7 are also formed by
the reaction of the metallocene dichloride dihydrochlo-
rides 4 and 5, respectively, with 4 equiv of methyl-
lithium (Scheme 3). The first 2 equiv of methyllithium
deprotonates the N-functions to generate the metal-
locene dichloride 2 or 3, which reacts with the further
2 equiv of methyllithium to form the dimethyl com-
pounds 6 and 7.
Treating the dimethyl complexes 6 and 7 in diethyl
ether with 4 equiv of HCl in methanolic solution affords
the metallocene dichloride dihydrochlorides 4 and 5 in
quantitative yields (Scheme 3). After the evolution of
(26) A¨ ndra, K. J . Organomet. Chem. 1968, 11, 567.
(27) Treating a toluene solution of CpN2ZrCl2 (3) with 2 equiv of
PhOLi leads to the formation of the diphenoxy compound CpN2Zr-
(PhO)2. The 1H and 13C NMR spectra show the presence of the
N-functionalized cyclopentadiene C5H5CH2CH2NiPr2 (CpNH) (50%),
which could not be removed.
(28) Chandra, G.; Lappert, M. F. J . Chem. Soc. A 1968, 1940.

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4156 Organometallics, Vol. 15, No. 20, 1996
Ta ble 1. 1H NMR Da ta for th e New Com p lexes 1-11
CpCH2 CH2N CHCH3 CHCH3
2.54 (m, 2 H) 2.65 (m, 2 H) 2.92 (m, 2 H) 0.94, 0.99 (2 d, 12 H, J ) 4.5 Hz)
J utzi et al.
C5H4
MR
1a 6.00-6.52 (m, 3 H)
3
2a 5.76, 6.13 (2 t, 8 H, 3J ) 2.6 Hz) 2.60 (m, 4 H) 2.93 (m, 4 H) 2.93 (m, 4 H) 0.90 (d, 24 H, J ) 6.6 Hz)
3
3
3
3a 5.77, 6.03 (2 t, 8 H, J ) 2.7 Hz) 2.57 (m, 4 H) 2.82 (m, 4 H) 2.90 (m, 4 H) 0.90 (d, 24 H, J ) 6.6 Hz)
4b 6.49, 6.61 (2 m, 8 H)
3.32 (m, 4 H) 3.32 (m, 4 H)c 3.63 (m, 4 H) 1.36, 1.43 (2 d, 24 H, J ) 6.5 Hz)
3
5b 6.47, 6.50 (2 m, 8 H)
3.24 (m, 4 H) 3.24 (m, 4 H)c 3.63 (m, 4 H) 1.36, 1.43 (2 d, 24 H, J ) 6.6 Hz)
3
3
3
6a 5.47, 5.80 (2 t, 8 H, J ) 2.5 Hz) 2.56 (m, 4 H) 2.74 (m, 4 H) 2.97 (m, 4 H) 0.98 (d, 24 H, J ) 6.6 Hz)
0.10 (s, 6 H)d
-0.06 (s, 6 H)d
2.00 (s, 4 H)e
1.95 (s, 4 H)e
3
3
7a 5.56, 5.82 (2 t, 8 H, J ) 3.4 Hz) 2.63 (m, 4 H) 2.63 (m, 4 H) 2.95 (m, 4 H) 0.96 (d, 24 H, J ) 6.5 Hz)
3
3
8a 5.72, 5.77 (2 t, 8 H, J ) 2.5 Hz) 2.14 (m, 4 H) 2.53 (m, 4 H) 2.88 (m, 4 H) 0.92 (d, 24 H, J ) 6.6 Hz)
3
3
9a 5.56, 5.68 (2 t, 8 H, J ) 2.7 Hz) 2.30 (m, 4 H) 2.49 (m, 4 H) 2.88 (m, 4 H) 0.92 (d, 24 H, J ) 6.6 Hz)
3
3
10a 5.80, 5.93 (2 t, 8 H, J ) 2.5 Hz) 2.52 (m, 4 H) 2.60 (m, 4 H) 2.87 (m, 4 H) 0.88 (d, 24 H, J ) 6.6 Hz)
3
3
11a 5.88, 6.00 (2 t, 8 H, J ) 2.7 Hz) 2.62 (m, 4 H) 2.62 (m, 4 H) 2.96 (m, 4 H) 0.99 (d, 24 H, J ) 6.6 Hz)
2.91 (s, 6 H)f
a
b
d
Measured in C6D6. Measured in CD3CN. c The proton resonance for the NH groups is observed at 10.90 ppm. R ) CH3. e R )
CH2C6H5. f R ) NMe2.
The data of the 13C NMR spectra of all compounds
show features consistent with the proposed structures
(see the Experimental Section). The benzyl ipso C
atom is a reliable indicator to distinguish the ligation
mode (ηx) of the benzyl ligand. There are no decisive
Ch a r t 2
differences between 8 and 9 and the structurally
30c
characterized complexes (CpSiMe3)2ZrBz2
and Cp2-
TiBz2,25c,d which show an η1 binding mode for the benzyl
ligand.
III. X-r a y Cr ysta l Str u ctu r e An a lysis of 2. Suit-
able crystals of 2 are obtained by crystallization from
dilute toluene solution. A single-crystal X-ray diffrac-
tion study established the expected bent-metallocene
type structure for (C5H4CH2CH2NiPr2)2TiCl2 (2). The
molecular structure and selected bond lengths and
angles are shown in Figure 1; crystallographic data are
given in Table 2.
with two η5-bonded monosubstituted cyclopentadienyl
ligands, as shown in Chart 2.
1
In the H NMR spectra of the complexes 2-11, a pair
of two pseudotriplets (AA′BB′ pattern) is observed for
the hydrogen atoms of the two cyclopentadienyl rings.
The methylene protons of the side chain appear as two
multiplets; the signals of the isopropyl group are
observed as a multiplet and a doublet. In the hydro-
chlorides 4 and 5, the methyl signals of the isopropyl
groups appear as two doublets.
The structure analysis shows that CpN2TiCl2 (2) forms
monomeric molecules. Neither an intramolecular nor
an intermolecular coordination of the additional (diiso-
propylamino)ethyl side chains is observed. The mol-
ecule possesses a crystallographic 2-fold axis passing
trough the titanium atom. The chlorine atoms together
with the centroids of the cyclopentadienyl rings form a
considerably distorted pseudotetrahedral coordination
geometry around the titanium with angles ranging from
94.4° (Cl-Ti-Cl′) to 132.6° ((Cp centroid)-Ti-(Cp cen-
troid)′, see Table 3). The CpN ring is nearly planar. The
methylene groups of the (diisopropylamino)ethyl side
chains attached to the CpN rings lie above the plane
defined by the carbon atoms of the CpN ring (2.9°). The
CpN rings are slightly staggered with the (diisopropy-
lamino)ethyl groups arranged at the opened side of the
sandwich. This molecular structure is similar to that
Noncoordination of the additional (diisopropylamino)-
ethyl function can be assumed for the complexes CpN
-
2
TiCl2 (2), CpN2ZrCl2 (3), and CpN2MR2 (M ) Ti, Zr; R )
Me, Bz, OPh, NMe2; 6-11). The signal due to the
methyl protons of the diisopropyl group is observed at
ca. 0.90 ppm. The two multiplets for the methylene
protons appear in the range of 2.1-2.9 ppm. The ring
protons are observed in the range of 5.5-6.1 ppm.
These values are nearly identical with those of the
(diisopropylamino)ethyl-substituted cyclopentadiene
C5H5CH2CH2NiPr2 (1).
In contrast, the protonation of the N-functions in
[(C5H4CH2CH2N(H)iPr2)2TiCl2]2+Cl- (4) and [(C5H4-
2
31a
observed for (C5H4Me)2TiCl2 with two methyl-substi-
CH2CH2N(H)iPr2)2ZrCl2]2+Cl- (5) causes a significant
2
tuted cyclopentadienyl ligands. The average Ti-C(Cp)
and the Ti-(Cp centroid) distances of 2.383(3) and 2.062
change of the 1H NMR shifts. All signals in 4 and 5
show a remarkable downfield shift compared to all other
complexes (see Table 1). Now the signal of the methyl
groups at the isopropyl unit is observed at ca. 1.40 ppm.
The two multiplets for the methylene protons appear
in the range of 3.3-3.6 ppm. The ring protons are
observed in the range of 6.4-6.7 ppm.
Å are similar to those found for the parent complex Cp2-
31b
TiCl2
(2.370(9) and 2.058 Å). As displayed in Table
3, all other bonding parameters for 2 (Ti-Cl ) 2.3681-
(11) Å, (Cp centroid)-Ti-(Cp centroid)′ ) 132.60°, (Cp
centroid)-Ti-Cl ) 105.7°, Cl-Ti-Cl′ ) 94.40(5)°) are
The methyl signals of the alkyl complexes CpN2TiMe2
(6) and CpN2ZrMe2 (7) are observed as expected as
singlets at 0.10 and -0.06 ppm, respectively. These
values are very similar to those of the parent complexes
(29) (a) Wailes, P. C.; Weigold, H.; Bell, A. P. J . Organomet. Chem.
1971, 33, 181. (b) Wailes, P. C.; Weigold, H.; Bell, A. P. J . Organomet.
Chem. 1972, 34, 155. (c) Samuel, E.; Rausch, M. D. J . Am. Chem. Soc.
1973, 95, 6263. (d) J ordan, R. F. J . Organomet. Chem. 1985, 294, 321.
(30) (a) Fachinetti, G.; Fochi, G.; Floriani, C. J . Chem. Soc., Dalton
Trans. 1976, 1946. (b) Brindley, P. B.; Scotton, M. J . J . Chem. Soc.,
Perkin Trans. 2 1981, 419. (c) Thiele, K.-H.; Bo¨hme, U. Z. Anorg. Allg.
Chem. 1993, 619, 1951.
29
Cp2MMe2 (M ) Ti, Zr). Similarly, the signals of the
hydrogen atoms of the benzyl groups in the complexes
CpN2TiBz2 (8) and CpN2ZrBz2 (9) show only small shift
differences compared with those of the parent com-
pounds Cp2MBz2.25,30ab
(31) (a) Petersen, J . L.; Dahl, L. F. J . Am. Chem. Soc. 1975, 97, 6422.
(b) Clearfield, A.; Warner, D. K.; Saladarriaga-Molina, C. H.; Ropal,
R.; Bernal, I. Can. J . Chem. 1975, 53, 1622.

+
+
Ti and Zr Bent-Sandwich Complexes
Organometallics, Vol. 15, No. 20, 1996 4157
F igu r e 1. Plot of the molecular structure of 2, with thermal ellipsoids at the 50% probability level. The hydrogen atoms
are omitted for clarity. Selected bond lengths (Å) and bond angles (deg): Ti(1)-Cl(1), 2.3683(11); Ti(1)-Cp(centroid), 2.062;
C(1)-C(6), 1.490(4); Cp(centroid)-Ti-Cp(centroid), 132.60°; Cl(1a)-Ti-Cl(1), 94.40°.
Ta ble 2. Cr ysta llogr a p h ic Da ta for Diffr a ction
Stu d ies of 2
tion. After 4 h, a HCl-MeOH mixture was added to
terminate the polymerization reaction. The productivi-
ties of the catalyst systems and the numbers of merit
(Mw, Mn) of the polyethylene determined by GPC
analysis are summarized in the Experimental Section.
The high values for the molecular weight distributions
Mw/Mn can be attributed to inhomogeneities in the
reaction mixture during the polymerization reaction
(high catalyst concentration, precipitation of polyethyl-
ene) and not to catalyst decomposition.32 The differ-
ences in the activity of precursors 2-5 in comparison
empirical formula
C26H44Cl2N2Ti
0.40 × 0.40 × 0.20
503.43
cryst size, mm3
fw
cryst syst
space group
lattice params
a, Å
monoclinic
C2/c
33.430(13)
b, Å
6.549(2)
c, Å
13.866(3)
â, deg
112.31(3)
2809(2)
V, Å3
Z
d
4
to that of the nonsubstituted parent metallocene di-
calcd, g/cm3
1.191
20d
chlorides Cp2MCl2
must be ascribed to influences of
diffractometer
programs
Siemens P21
Siemens SHELXTLplus/SHELXL-93
the additional (diisopropylamino)ethyl side chains of
the CpN ligands. The activities of the titanium com-
pounds 2 and 4 are comparable to those of titanocene
complexes with substituted cyclopentadienyl ligands
F(000)
1080
0.510
-100
55
3268
145
µ(Mo KR), mm-1
temp, °C
2θmax, deg
i
such as CpR2TiCl2 (R ) Pr).20d The zirconocene com-
no. of data collected
no. of params refined
residuals
plexes 3 and 5 show rather low polymerization activities
compared to other substituted zirconocene catalysts.20d
This difference may be due to the nonoptimized reaction
conditions.
RF ) 0.0547 for
2050 rflns (I > 2σ(I))
2
RwF ) 0.1209 (all data)
largest peak in
final diff map, e/Å3
abs cor
0.6
P h en ylsila n e Deh yd r ocou p lin g Rea ction s. High
catalytic activity in the dehydrocoupling of phenylsilane
is observed for the complexes CpN2TiMe2 (6), CpN2ZrMe2
(7), CpN2TiBz2 (8), and CpN2Ti(OPh)2 (10). Reaction
of these complexes with phenylsilane at room temper-
ature under an inert atmosphere over a period of several
days leads to the production of poly(phenylsilanes) in
excellent yields. The polymer products are recovered
by filtration of the reaction solution through a Florisil
column, followed by vacuum evaporation of the solvent.
The poly(phenylsilanes) thus obtained are extremely
viscous oils.
semiempirical
within the range established for the complexes (C5H5)2-
TiCl231b and (C5H4Me)2TiCl2.31a This demonstrates that
the introduction of the two (diisopropylamino)ethyl
functions does not significantly affect the basic molec-
ular structure.
IV. P olym er iza tion a n d Deh yd r ocou p lin g Rea c-
tion s. Eth ylen e P olym er iza tion Rea ction s. The
metallocene dichlorides and dihydrochlorides of tita-
nium and zirconium 2-5 are catalyst precursors for the
polymerization of ethylene. In the reaction of the
complexes 2 and 3 with 500 equiv of methylaluminox-
ane in toluene, the color of the solution immediately
turns yellow, which corresponds to the color of the
dimethyl compounds CpN2MMe2 (6 and 7) in this
solvent. This is in agreement with the assumption
that methylaluminoxane acts first as a methylation
reagent to form the dimethyl compounds as intermedi-
ates. The further equivalents of methylaluminoxane
abstract one methyl group by forming cationic species,
which are the active catalyst systems. In the case of
the metallocene dichloride dihydrochlorides 4 and 5, 2
equiv of MAO acts first as a deprotonating reagent to
form the metallocene dichlorides 2 and 3 as intermedi-
ates. The further reaction to active catalytic species is
analogous to that described above. The reaction mix-
ture was stirred at ambient temperature, and ethylene
(atmospheric pressure) was bubbled through the solu-
As generally described in the literature,21 poly(phen-
ylsilanes) synthesized via the dehydrocoupling method
with dimethyltitanocene and dimethylzirconocene cata-
lysts are predominantly atactic polymers. They consist
of linear, cyclic, and branched species; therefore, their
1
characterization is quite complicated. The H and 29Si
NMR spectra give only a small amount of information
concerning the details of the polymer structure; only
broad unresolved resonances are observed in the range
of 4-5 ppm and -50 to -70 ppm, respectively. The IR
spectra show, in addition to the bands due to the phenyl
substituents, characteristic, intense νSiH bands at ca.
2100 cm-1, typical for trisubstituted Si-H compounds,33a
and strong δSiH bands at ca. 910 cm-1, typical for the
bending mode of SiH2 groups.33b
(32) Catalyst decomposition can be excluded. The catalyst precursors
can be recycled (J utzi, P.; Redeker, T., unpublished results).

+
+
4158 Organometallics, Vol. 15, No. 20, 1996
J utzi et al.
31a
Ta ble 3. Bon d in g P a r a m eter s for (C5H4CH2CH2NiP r 2)2TiCl2 (2), (C5H5)2TiCl2,31b a n d (C5H4Me)2TiCl2
compound
Ti-Cl (Å)
Cl-Ti-Cl (deg)
Cp-Ti (Å)
Cp-Ti-Cp (deg)
(C5H4CH2CH2NiPr2)2TiCl2 (2)
(C5H5)2TiCl2
(C5H4Me)2TiCl2
2.3682(11)
2.364(2)
2.362(2)
94.40(5)
94.53(6)
93.15(8)
2.062
2.059
2.067
132.6
130.97
130.2
The polyphenylsilanes synthesized by 6-8 and 10
exhibit analytical data similar to those described above.
The 1H NMR spectra show broad, unresolved signals
in the range of 4.5-5.5 ppm and the 29Si NMR spectra
in the range of -55 to -65 ppm. The characteristic νSiH
and δSiH bands are observed at 2090-2110 cm-1 and at
910-920 cm-1, respectively. The mass spectra show
fragments of linear and cyclic polymers up to the parent
ion of the octamer.34 The amount of linear, cyclic, and
branched oligomers has not yet been determined. A
detailed analysis of the polymers will be subject of
further investigations.
V. Effect of th e (Diisop r op yla m in o)eth yl F u n c-
tion . Metallocene dichlorides Cp2MCl2 (M ) Ti, Zr) are
electronically unsaturated (16-VE species) and act as
weak Lewis acids.35 Therefore, they should react with
Lewis bases like tertiary amines to form adducts of
the type Cp2MCl2rNR3. Such reactions are rarely
discussed in the literature and are controversial.36 In
our experiments with Cp2MCl2 (M ) Ti, Zr) and the
tertiary amines EtNMe2 and EtNiPr2, respectively, no
adducts could be isolated. Furthermore, 1H NMR
spectroscopic investigations gave no evidence for an
interaction between the metallocene dichlorides and the
amines in solution.
A Lewis acid-Lewis base interaction between a metal
center and the N atom of the amino group in the
functionalized Cp) and Cp∧ ligands (Cp) ) C5H4CH2-
CH2NMe2; Cp∧ ) C5Me4CH2CH2NMe2) could be proved
for many complexes of s-, p-, d-, and f-block elements.1-8
Due to the potential chelate effect of the N-functional-
ized side chains, the metallocene dichlorides of the type
Cp)2MCl2, which had been synthesized by our group
only recently,7 and the metallocene dichlorides of the
type CpN2MCl2 (this work) might show an intramolecu-
lar coordination. But until now, such an intramolecular
interaction has not been observed for this kind of
metallocene-type complex.
However, an intermolecular coordination of the N-
functionalized side chains is observed in Cp)2MCl2 as
well as in CpN2MCl2. Amorphous solids precipitate from
concentrated benzene solutions. These solids are coor-
dination polymers and not decomposition products.22,37
The coordination polymer of Cp)2MCl2 precipitates
immediately. In contrast, the precipitation process of
the compounds CpN2MCl2 takes several days. The
smaller tendency for an intermolecular coordination of
CpN2MCl2 can be attributed to steric effects of the
bulkier (diisopropylamino)ethyl-functionalized side chain.
Due to the lower polymerization tendency a complete
characterization of CpN2MCl2 in dilute solution is pos-
sible. 1H NMR spectroscopy indicates the presence of
monomeric species. Furthermore, it is possible to grow
crystals of monomeric 2 from a dilute toluene solution
(see section III, X-ray Crystal Structure Analysis of 2).
There is no evidence of an interaction of the N-functions
with the metal centers for the monomers either in
solution or in the solid state.
In contrast to the parent complexes Cp2MCl2, the
N-functionalized derivatives CpN2MCl2 are extremely
air- and moisture-sensitive. This is due to the effect of
the amino group which supports the hydrolysis process
by trapping the evolving hydrogen chloride. A compa-
rable phenomenon is described by Rausch et al.10b for
the half-sandwich species Cp)TiCl3.
In the hydrochlorides CpN2MCl2‚2HCl (4, 5), the
amino groups in their protonated forms dramatically
change the solubility as well as the stability toward air
and moisture. In contrast to CpN2MCl2, the hydrochlo-
rides 4 and 5 show an excellent solubility and stability
in polar solvents such as chloroform and acetonitrile.
Furthermore, solvolysis of the M-Cl bonds in protic
solvents such as methanol is not observed. Complex 4
is stable even in water for several hours. This phenom-
enon can be explained by a kind of “intramolecular
buffer function” of the protonated amino groups.38
The first attempts to use the metallocene dichlorides
CpN2MCl2 and also the protonated species CpN2MCl2‚
2HCl in the polymerization of ethylene have been suc-
cessful (see section IV, Polymerization Reactions). Be-
cause of their high stability to air and moisture, the
hydrochlorides CpN2MCl2‚2HCl (4) and (5) are preferred
candidates as precursors in Ziegler-Natta catalysis.
Mechanistic studies concerning coordination of the
N-functions during various steps of the catalytic process
to stabilize the intermediate cationic species are in
progress.
Similary, the additional side chains obviously do not
reduce the catalytic activity of the alkyl and phenoxy
derivatives CpN2MR2 (6-8, 10; R ) Me, Bz, PhO) in the
dehydrocoupling of phenylsilane (see section IV, Dehy-
drocoupling Reactions). The yields of produced poly-
mers and the degrees of polymerization are comparable
to those of the analogous parent complexes Cp2MR2.21
Mechanistic studies concerning the influence of the
additional amino functions in this kind of catalysis will
be also the subject of further investigations.
VI. Con clu sion . It has been demonstrated that it
is possible to synthezise metallocene-type compounds
of titanium and zirconium containing two (diisopropyl-
amino)ethyl-substituted cyclopentadienyl ligands (CpN).
(36) (a) Anagnostopoulos, A. K. Chem. Chron. Epistem. Ekdosis
1969, 34, 140. (b) Baye, L. J . Synth. Inorg. Met.-Org. Chem. 1972, 2,
47.
(37) This could be proved by the reaction of the solid with methanolic
HCl. The polymer structure is destroyed, and the protonation of the
N-functions results in the formation of the monomer metallocene
dichlorides dihydrochlorides Cp)2MCl2‚2HCl in nearly quantitative
yields.
(38) The nucleophilic attack of the hydroxide anion is probably the
first step in the decomposition process of the dichlorides 2 and 3. In
case of the hydrochlorides 4 and 5, the protonated amino group can
function as an intramolecular buffer.
(33) (a) Kniseley, R. N.; Fassel, V. A.; Conrad, E. E. Spectrochim.
Acta 1959, 651. (b) Ho¨fler, F.; Bauer, G.; Hengge, E. Spectrochim. Acta
1976, 32a, 1435.
(34) On the spectrometer used, only fragments with m/ z <1000
could be detected.
(35) (a) Karsch, H. H.; Deubelly, B.; Hofmann, J .; Pieper, U.; Mu¨ller,
G. J . Am. Chem. Soc. 1988, 110, 3654. (b) Hey-Hawkins, E.; Linden-
berg, F. Chem. Ber. 1992, 125, 1815. (c) Lindenberg, F.; Hey-Hawkins,
E. Z. Anorg. Allg. Chem. 1995, 621, 1531. See also references cited
therein.

+
+
Ti and Zr Bent-Sandwich Complexes
Organometallics, Vol. 15, No. 20, 1996 4159
NMR (CDCl3): δ 0.99, 1.00 (2d, 3J ) 3.2 Hz, 2 × 6H, CHCH3),
2.44-2.50 (m, 2 H, CpCH2), 2.54-2.61 (m, 2H, CH2N), 2.90-
2.93 (m, 2H, allyl-Cp H), 2.97-3.07 (m, 2H, CHCH3), 6.01,
6.16, 6.22, 6.24, 6.40, 6.43 (m, 3H, vinyl-Cp H). 1H NMR
(1) In dilute solution, the metallocene dichlorides 2
and 3 exist as monomers without an intramolecular
coordination of the amino groups; in concentrated solu-
tion, the formation of polymers by an intermolecular
coordination is a rather slow process. The crystal
structure of the coordination polymer has been unknown
until now. The structure of the monomer species could
be determined for 2 by an X-ray crystal structure
analysis. There is no evidence for an interaction of the
N-functions with the metal center.
(2) The solubility of the complexes CpN2MCl2 (2, 3) in
nonpolar solvents is raised dramatically in comparison
to that of the parent metallocene derivatives Cp2MCl2.
(3) The hydrochlorides CpN2MCl2‚2HCl (4, 5) show an
exceptional stability to air and moisture. Furthermore,
their high solubilty in protic solvents is of special
interest with regard to organometallic chemistry in
water.39
(4) The metallocene dichlorides 2 and 3 and also the
hydrochlorides 4 and 5 are precatalysts in the polym-
erization of ethylene. Because of their easy handling
due to their exceptional stability, the hydrochlorides 4
and 5 are particulary suitable for employment in this
kind of catalysis.
(5) The alkyl and alkoxy derivatives CpN2MR2 (6-8)
catalyze the dehydrogenative coupling of phenylsilane
to oligosilanes in excellent yields.
3
(C6D6): δ 0.94, 0.96 (2 d, J ) 4.5 Hz, 2 × 6H, CHCH3), 2.50-
2.57 (m, 2 H, CpCH2), 2.62-2.68 (m, 2H, CH2N), 2.77-2.80
(m, 2H, allyl-Cp H), 2.87-2.97 (m, 2H, CHCH3), 6.00, 6.21,
6.23, 6.32, 6.49, 6.52 (m, 3H, vinyl-Cp H). 13C{1H} NMR
(CDCl3): δ 20.6 (CHCH3), 32.6, 33.2 (CpCH2), 41.1, 43.5
(CH2N), 45.2, 45.9 (allyl-Cp C), 48.5, 48.7 (CHCH3), 126.1,
126.4, 130.3, 132.3, 133.2, 134.9 (ring -CHd), 145.6, 148.1
(ring dCCH2CH2). MS (EI; m/ z (relative intensity, %)): 178
([M - CH3]+, 5), 114 ((iC3H7)2NCH2+, 100), 72 (CH2NH(iC3H7)+,
42). Anal. Calcd for C13H23N (193.33): C, 80.76; H, 11.99; N,
7.24. Found: C, 80.45; H, 11.92; N, 7.00.
(η5-C5H4CH2CH2NiP r 2)2TiCl2 (2). To a solution of 1.92 g
(10.1 mmol) of TiCl4 dissolved in 80 mL of toluene cooled to
-40 °C was added dropwise with stirring a suspension of 20.2
mmol of CpNLi in 80 mL of diethyl ether (prepared by addition
of 12.6 mL (20.2 mmol) of n-butyllithium (1.6 M in n-hexane)
to a solution of 3.90 g (20.2 mmol) of CpNH in diethyl ether).
The reaction mixture was warmed to room temperature over
6 h and then stirred for an additional 10 h. The deep red
solution was filtered, and the solvent was removed in vacuo.
The residue was washed with 3 × 30 mL of cold pentane (-40
°C), leaving 2.5 g (4.97 mmol, 49%) of 2 as a deep red solid.
The product can be crystallized from toluene to form red
crystals. 1H NMR (C6D6): δ 0.90 (d, 3J ) 6.6 Hz, 24H, CHCH3),
3
2.60 (m, 4H, CpCH2), 2.93 (m, 8H, NCH2, CHCH3), 5.76 (t, J
) 2.6 Hz, 4H, Cp H), 6.13 (t, 3J ) 2.7 Hz, 4H, Cp H). 13C
NMR (C6D6): δ 21.0 (CHCH3), 33.1 (CpCH2), 45.6 (CH2N), 48.2
(CHCH3), 114.6, 122.9 (ring -CHd), 136.7 (ring dCCH2CH2).
MS (LSIMS; m/ z (relative intensity, %)): 503 ([M + 1H]+, 3),
468 ([M - 2Cl]+, 3), 114 ([(iC3H7)2NCH2]+, 100), 65 ([C5H5]+,
8). Mp: 156 °C dec. Anal. Calcd for C26H44Cl4N2Ti (503.43):
C, 62.03; H, 8.80; N, 5.56. Found: C, 61.92; H, 8.68; N, 5.43.
Exp er im en ta l Section
Gen er a l Com m en ts. All experiments were carried out
under an atmosphere of dried, oxygen-free argon by using
standard Schlenk techniques. When ethylene was used as a
reagent, the gas provided a protective atmosphere. Solvents
were dried by using standard procedures and distilled prior
to use. All other reagents were used as purchased. 1H (300.1
MHz) and 13C{1H} (75.5 MHz) NMR spectra were obtained
using a Bruker AM 300 spectrometer. Chemical shifts for 1H
and 13C{1H} spectra were recorded in ppm downfield from TMS
and referenced with internal deuteriochloroform, deuterioben-
zene, deuterioacetonitrile, or deuteriomethanol. The mass
spectra were determined by using a VG AutoSpec instrument.
Only characteristic fragments and isotopes of the highest
abundance are listed. Melting points were determined in
sealed capillaries with a Bu¨chi 510 melting point determina-
tion apparatus and are uncorrected. Elemental analyses were
carried out by Analytisches Labor der Fakulta¨t fu¨r Chemie,
Bielefeld, Germany.
Ma ter ia ls. Titanium tetrachloride was distilled prior to
use. Zirconium tetrachloride was used as purchased. Zr-
(NMe2)4 was prepared as described in the literature.40
C5H5CH2CH2NiP r 2 ≡ Cp NH (1). Over 1 h, to a solution of
17.62 g (200 mmol) of CpNa in 100 mL of THF cooled to 0 °C
(prepared by addition of 13.2 g (200 mmol) of CpH to a
suspension of 4.60 g (200 mmol) of NaH in THF) was added
dropwise with stirring 30.1 g (184 mmol) of 2-chloro-1-
(diisopropylamino)ethane. The reaction mixture was warmed
to room temperature within 1 h and then refluxed for an
additional 2 h. After the solvent was removed in vacuo (20
Torr) the residue was hydrolyzed with 150 mL of water and
extracted with 3 × 100 mL of petroleum ether. The combined
organic layers were dried with sodium sulfate. Volatile
products were removed in vacuo, and the crude product was
distilled (76-77 °C/2 Torr) to yield 21.2 g (110 mmol, 60%) of
the (diisopropylamino)ethyl-substituted cyclopentadiene 1 in
the form of a colorless liquid as a mixture of two isomer. 1H
(η5-C5H4CH2CH2NiP r 2)2Zr Cl2 (3). To a suspension of 2.35
g (10.10 mmol) of ZrCl4 in 80 mL of toluene cooled to -40 °C
was added dropwise with stirring a suspension of 20.20 mmol
of CpNLi in 80 mL of diethyl ether (prepared by addition of
12.60 mL (20.20 mmol) of n-butyllithium (1.6 M in n-hexane)
to a solution of 3.90 g (20.20 mmol) of CpNH in diethyl ether).
The reaction mixture was warmed to room temperature over
4 h and then stirred for an additional 24 h. The yellow solution
was filtered, and the solvent was removed in vacuo. The
residue was washed with 2 × 50 mL of cold (-40 °C) pentane,
leaving 3.15 g (5.80 mmol, 57%) of 3 as a pale yellow solid.
The product can be crystallized from toluene to form colorless
needles. 1H NMR (C6D6): δ 0.90 (d, 3J ) 6.6 Hz, 24H, CHCH3),
2.57 (t, 3J ) 6.5 Hz, 4H, CpCH2), 2.82 (m, 4H, NCH2), 2.90
3
3
(m, 4H, CHCH3), 5.77 (t, J ) 2.7 Hz, 4H, Cp H), 6.02 (t, J )
2.7 Hz, 4H, Cp H). 13C NMR (C6D6): δ 21.1 (CHCH3), 33.0
(CpCH2), 47.0 (CH2N), 48.6 (CHCH3), 109.1, 113.2, 113.5, 117.1
(ring -CHd), 130.3 (ring dCCH2CH2). MS (LSIMS; m/ z
(relative intensity, %)): 545 ([M + 1H]+, 1), 114 ([(iC3H7)2-
NCH2]+, 100), 65 ([C5H5]+, 2). Mp: 120 °C dec. Anal. Calcd
for
C26H44N2Cl2Zr (546.78): C, 57.11; H, 8.11; N, 5.12.
Found: C, 56.86; H, 8.73; N, 4.93.
[(η5-C5H4CH2CH2N(H)iP r 2)2TiCl2]2+Cl- (4). A 550 mg
2
(1.09 mmol) amount of 2 was dissolved in 15 mL of MeOH
(saturated with HCl gas) and then stirred for ca. 30 min. The
solution was evaporated in vacuo, leaving 628 mg (1.09 mmol,
100%) of 4 as an orange-brown solid. The product can be
crystallized from acetonitrile to form deep red crystals. 1H
3
NMR (CD3OD): δ 1.39, 1.40 (2d, J ) 6.6 Hz, 24H, CHCH3),
3.33 (m, 4H, CpCH2), 3.56 (m, 4H, NCH2), 3.78 (m, 4H,
3
3
CHCH3), 6.44 (t, J ) 2.5 Hz, 4H, Cp H), 6.74 (t, J ) 2.7 Hz,
4H, Cp H). 1H NMR (CD3CN): δ 1.36, 1.43 (2 d, J ) 6.5 Hz,
3
24H, CHCH3), 3.32 (m, 8H, CpCH2, NCH2), 3.63 (m, 4H,
CHCH3), 6.49 (m, 4H, Cp H), 6.61 (m, 4H, Cp H), 10.90 (broad
s, 2H, NH). 13C NMR (CD3OD): δ 17.2, 18.8 (CHCH3), 29.2
(CpCH2), 47.3 (CH2N), 56.5 (CHCH3), 115.8, 125.1 (ring
(39) Herrmann, W. A.; Kohlpaintner, C. W. Angew. Chem. 1993, 105,
1588.
(40) Bradley, D. C.; Thomas, I. M. J . Am. Chem. Soc. 1960, 3857.

+
+
4160 Organometallics, Vol. 15, No. 20, 1996
J utzi et al.
-CHd), 132.6 (ring dCCH2CH2). Mp: 177 °C dec. Anal.
Calcd for C26H46Cl4N2Ti (576.35): C, 54.18; H, 8.04; N, 4.86.
Found: C, 53.89; H, 8.30; N, 4.72.
After the solvent of the red-brown suspension was removed
in vacuo, the residue was extracted with 40 mL of toluene.
The extract was filtered, and the solvent was removed in
vacuo. The red-brown residue was washed with 40 mL of cold
(-60 °C) pentane, leaving 470 mg (0.76 mmol, 41%) of 8 as a
purple solid. Crystallization from toluene affords purple
crystals.
[(η5-C5H4CH2CH2N(H)iP r 2)2Zr Cl2]2+Cl- (5). A 530 mg
2
(0.97 mmol) amount of 3 was dissolved in 15 mL of MeOH
(saturated with HCl gas), and the mixture was then stirred
for ca. 30 min. Volatile products were removed in vacuo,
leaving 600 mg (0.97 mmol, 100%) of 5 as a colorless solid. An
analytically pure compound could be obtained by crystalliza-
tion from acetonitrile. 1H NMR (CD3OD): δ 1.39, 1.41 (2 d,
3J ) 6.6 Hz, 24H, CHCH3), 3.19 (m, 4H, CpCH2), 3.46 (m, 4H,
F r om [(C5H4CH2CH2N(H)iP r 2)2TiCl2]2+Cl- (4). Analo-
2
gous procedures with 4 equiv of benzylmagnesium bromide
were used, as described above for 2; yield 38%. 1H NMR
(C6D6): δ 0.92 (d, 3J ) 6.6 Hz, 24H, CHCH3), 2.00 (s, 4H,
TiCH2), 2.14 (m, 4H, CpCH2), 2.53 (m, 4H, NCH2), 2.88 (m,
3
NCH2), 3.78 (m, 4H, CHCH3), 6.45 (t, J ) 2.7 Hz, 4H, Cp H),
6.61 (t, 3J ) 2.7 Hz, 4H, Cp H). 1H NMR (CD3CN): δ 1.36,
1.43 (2 d, 3J ) 6.5 Hz, 24H, CHCH3), 3.24 (m, 8H, CpCH2,
NCH2), 3.63 (m, 4H, CHCH3), 6.47 (m, 4H, Cp H), 6.50 (m,
4H, Cp H), 10.90 (br s, 2H, NH). 13C NMR (CD3OD): δ 17.3,
18.9 (CHCH3), 28.8 (CpCH2), 48.0 (CH2N), 56.6 (CHCH3),
113.5, 119.7 (ring -CHd), 129.2 (ring dCCH2CH2). Mp: 170
°C dec. Anal. Calcd for C26H46N2Cl4Zr (619.70): C, 50.39; H,
7.48; N, 4.52. Found: C, 50.18; H, 7.35; N, 4.60.
3
3
4H, CHCH3), 5.72 (t, J ) 2.5 Hz, 4H, Cp H), 5.77 (t, J ) 2.5
3
Hz, 4H, Cp H), 6.93 (m, 6H, ortho and para Bz H), 7.22 (t, J
) 7.6 Hz, 4H, meta Bz H). 1H NMR (CDCl3): δ 0.95 (d, J )
3
6.5 Hz, 24H, CHCH3), 1.81 (s, 4H, TiCH2), 2.14 (m, 4H,
CpCH2), 2.53 (m, 4H, NCH2), 2.96 (m, 4H, CHCH3), 5.80 (t, 3J
3
) 2.5 Hz, 4H, Cp H), 5.85 (t, J ) 2.5 Hz, 4H, Cp H), 6.74 (d,
3J ) 7.1 Hz, 4H, ortho Bz H), 6.81 (t, 3J ) 7.3 Hz, 2H, para Bz
H), 7.12 (t, J ) 7.7 Hz, 4H, meta Bz H). 13C NMR (C6D6): δ
3
(η5-C5H 4CH 2CH 2NiP r 2)2TiMe2 (6). F r om (C5H 4CH 2-
CH2NiP r 2)2TiCl2 (2). To a suspension of 300 mg (0.60 mmol)
of 2 in 20 mL of diethyl ether cooled to -50 °C was added
dropwise with stirring 0.75 mL (1.20 mmol) of methyllithium
(1.6 M in diethyl ether). The reaction mixture was warmed
to room temperature within 6 h and then stirred for an
additional 10 h. After the solvent of the dark solution was
removed in vacuo, the residue was extracted with 15 mL of
toluene. The extract was filtered and the solvent was removed
in vacuo, leaving 260 mg (0.56 mmol, 94%) of 6 as a deep
yellow oil.
21.1 (CHCH3), 33.0 (CpCH2), 47.3 (CH2N), 48.5 (CHCH3), 73.3
(TiCH2), 114.9, 117.4 (Cp ring C), 121.8 (para Bz C4), 126.4
(meta Bz C3), 128.8 (ortho Bz C2), 129.3 (Cp ring dCCH2CH2),
154.5 (Bz C1). MS (CI; m/ z (relative intensity, %)): 432 ([M
- 2C7H7]+, 6), 114 ([(iC3H7)2NCH2]+, 100), 91 ([C7H7]+, 4).
Mp: 91 °C dec. Anal. Calcd for C40H58N2Ti (614.79): C, 78.14;
H, 9.50; N, 4.55. Found: C, 77.36; H, 9.63; N, 4.46.
(η5-C5H 4CH 2CH 2NiP r 2)2Zr Bz2 (9). F r om (C5H 4CH 2-
CH2NiP r 2)2Zr Cl2 (3). To a suspension of 940 mg (1.72 mmol)
of 3 in 70 mL of diethyl ether cooled to -50 °C was added
dropwise with stirring 4.14 mL (3.44 mmol) of benzylmagne-
sium bromide (0.83 M in ether) diluted in 45 mL of diethyl
ether over 20 min. The reaction mixture was warmed to room
temperature within 6 h and then stirred for an additional 10
h. After the solvent of the yellow suspension was removed in
vacuo, the residue was extracted with 40 mL of toluene. The
extract was filtered, and the solvent was removed in vacuo.
The yellow residue was washed with 40 mL of cold (-60 °C)
pentane, leaving 590 mg (0.90 mmol, 52%) of 9 as a bright
yellow solid.
F r om [(C5H4CH2CH2N(H)iP r 2)2TiCl2]2+Cl- (4). Analo-
2
gous procedures with 4 equiv of methyllithium were followed,
as described above for 2; yield 87%. 1H NMR (C6D6): δ 0.1 (s,
3
6H, TiCH3), 0.98 (d, J ) 6.6 Hz, 24H, CHCH3), 2.56 (m, 4H,
CpCH2), 2.74 (m, 4H, NCH2), 2.97 (m, 4H, CHCH3), 5.47 (t, 3J
) 2.5 Hz, 4H, Cp H), 5.80 (t, 3J ) 2.5 Hz, 4H, Cp H). 13C
NMR (C6D6): δ 21.1 (CHCH3), 33.6 (CpCH2), 44.9 (TiCH3), 47.3
(CH2N), 48.6 (CHCH3), 111.0, 114.7 (ring -C). MS (LSIMS;
m/ z (relative intensity, %)): 463 ([M + 1H]+, 4), 432 ([M -
2CH3]+, 6), 114 ([(iC3H7)2NCH2]+, 100), 65 ([C5H5]+, 5). Anal.
Calcd for C28H50N2Ti (462.60): C, 72.69; H, 10.89; N, 6.05.
Found: C, 71.82; H, 11.27; N, 5.77.
F r om [(C5H4CH2CH2N(H)iP r 2)2Zr Cl2]2+Cl- (5). Analo-
2
gous procedures with 4 equiv of benzylmagnesium bromide
were followed, as described above for 3; yield 57%. 1H NMR
(C6D6): δ 0.92 (d, 3J ) 6.6 Hz, 24H, CHCH3), 1.95 (s, 4H,
ZrCH2), 2.30 (m, 4H, CpCH2), 2.49 (m, 4H, NCH2), 2.88 (m,
(η5-C5H 4CH 2CH 2NiP r 2)2Zr Me2 (7). F r om (C5H 4CH 2-
CH2NiP r 2)2Zr Cl2 (3). To a suspension of 740 mg (1.35 mmol)
of 3 in 30 mL of diethyl ether cooled to -70 °C was added
dropwise with stirring 1.69 mL (2.70 mmol) of methyllithium
(1.6 M in diethyl ether). The reaction mixture was warmed
to room temperature over 6 h and then stirred for an additional
10 h. After the solvent of the yellow solution was removed in
vacuo, the residue was extracted with 15 mL of toluene. The
extract was filtered and the solvent was removed in vacuo,
leaving 640 mg (1.26 mmol, 94%) of 7 as a yellow oil.
3
3
4H, CHCH3), 5.56 (t, J ) 2.7 Hz, 4H, Cp H), 5.68 (t, J ) 2.7
3
Hz, 4H, Cp H), 6.92 (t, J ) 7.3 Hz, 2H, para Bz H), 6.98 (d,
3J ) 7.1 Hz, 4H, ortho Bz H), 7.25 (t, J ) 7.5 Hz, 4H, meta
3
Bz H). 13C NMR (C6D6): δ 21.0 (CHCH3), 32.5 (CpCH2), 47.6
(CH2N), 48.4 (CHCH3), 61.3 (ZrCH2), 111.4, 123.9 (Cp ring C),
121.1 (para Bz C4), 126.1 (ortho and meta Bz C2 and C3), 126.8
(Cp ring dCCH2CH2), 152.8 (Bz C1). MS (CI; m/ z (relative
intensity, %)): 565 ([M - C7H7]+, 17), 194 ([CpNH + H]+, 3),
178 ([CpNH - CH3]+, 3), 114 ([(iC3H7)2NCH2]+, 34), 91 ([C7H7]+,
7), 72 ([CH2NH(iC3H7)]+, 2). Mp: 85 °C dec.
F r om [(C5H4CH2CH2N(H)iP r 2)2Zr Cl2]2+Cl- (5). Analo-
2
gous procedures with 4 equiv of MeLi as were followed,
described above for 3; yield 89%. 1H NMR (C6D6): δ -0.06 (s,
(η5-C5H4CH2CH2NiP r 2)2Ti(OP h )2 (10). To a suspension
of 1.25 g (2.48 mmol) of 2 in 30 mL of toluene cooled to -20
°C was added dropwise with stirring 497 mg (4.97 mmol) of
PhOLi in 20 mL of benzene (prepared by addition of 3.11 mL
(4.97 mmol) of n-butyllithium (1.6 M in n-hexane) to a solution
of 468 mg (4.97 mmol) of phenol in benzene). The reaction
mixture was warmed to room temperature over 6 h and then
stirred for an additional 10 h. The solution was filtered, and
the solvent was removed in vacuo. The yellow residue was
washed with 40 mL of pentane, leaving 1.38 g (2.23 mmol,
3
6H, ZrCH3), 0.96 (d, J ) 6.5 Hz, 24H, CHCH3), 2.63 (m, 8H,
CpCH2, NCH2), 2.95 (m, 4H, CHCH3), 5.56 (t, 3J ) 3.4 Hz,
3
4H, Cp H), 5.82 (t, J ) 3.4 Hz, 4H, Cp H). 13C NMR (C6D6):
δ 21.1 (CHCH3), 30.3 (ZrCH3), 33.1 (CpCH2), 47.4 (CH2N), 48.6
(CHCH3), 107.9, 111.5 (ring -CHd), 126.7 (ring dCCH2CH2).
MS (CI; m/ z (relative intensity, %)): 505 ([M + 1H]+, 4), 193
([CpN]+, 13), 114 ([(iC3H7)2NCH2]+, 100). Anal. Calcd for
C
28H50N2Zr (505.94): C, 66.47; H, 9.96; N, 5.53. Found: C,
64.87; H, 9.74; N, 5.00.
(η5-C5H 4CH 2CH 2NiP r 2)2TiBz2 (8). F r om (C5H 4CH 2-
CH2NiP r 2)2TiCl2 (2). Over 20 min, to a suspension of 946
mg (1.87 mmol) of 2 in 70 mL of diethyl ether cooled to -60
°C was added dropwise with stirring 4.40 mL (3.65 mmol) of
benzylmagnesium bromide (0.83 M in ether) diluted in 45 mL
of diethyl ether. The reaction mixture was warmed to room
temperature over 6 h and then stirred for an additional 10 h.
89%) of 10 as a yellow solid. 1H NMR (C6D6): δ 0.88 (d, J )
3
6.6 Hz, 24H, CHCH3), 2.52 (m, 4H, CpCH2), 2.60 (m, 4H,
3
NCH2), 2.87 (m, 4H, CHCH3), 5.80 (t, J ) 2.5 Hz, 4H, Cp H),
3
3
5.93 (t, J ) 2.5 Hz, 4H, Cp H), 6.84 (t, J ) 7.3 Hz, 2H, para
3
3
Ph H), 6.91 (t, J ) 7.6 Hz, 4H, ortho Ph H), 7.23 (t, J ) 7.4
Hz, 4H, meta Ph H). 13C NMR (C6D6): δ 21.0 (CHCH3), 32.5
(CpCH2), 45.6 (CH2N), 48.4 (CHCH3), 113.0, 119.1, 138.3 (Cp

+
+
Ti and Zr Bent-Sandwich Complexes
Organometallics, Vol. 15, No. 20, 1996 4161
C), 114.4 (ortho Ph C), 118.6 (para Ph C), 129.4 (meta Ph C),
170.9 (Ph C). MS (CI; m/ z (relative intensity, %)): 619 ([M +
1H]+, 1), 525 ([M - PhO]+, 1), 432 ([M - 2PhO]+, 4), 114
([(iC3H7)2NCH2]+, 48), 95 ([C6H7O]+, 32). Mp: 82 °C. Anal.
Calcd for C38H54N2O2Ti (618.73): C, 73.76; H, 8.79; N, 4.52.
Found: C, 73.82; H, 8.78; N, 4.18.
(Ph3Si5H+, 11), 421 (Ph4Si4H+, 11), 450 (Ph4Si5H2+, 18), 526
(Ph5Si5H+, 7), 634 (Ph6Si6H4+, 5), 636 (Ph6Si6H6+, 5), 740
(Ph7Si7H5+, 12), 846 (Ph8Si8H6+, 1). IR (KBr): νSi-H 2091.2,
911 cm-1
.
With (C5H4CH2CH2NiP r 2)2Zr Me2 (7). A 50 mg (0.10
mmol) amount of 7 was dissolved in 5 mL of toluene. Under
an argon atmosphere 760 mg (7.00 mmol) of phenylsilane was
added to this solution. Evolution of gas commenced. After
the solution was stirred for 2 days at room temperature, it
was added to a column of Florisil. The polymer was recovered
by elution with toluene followed by vacuum evaporation of the
eluent. The product was obtained as a colorless, extremely
viscous liquid (600 mg, 79%). 1H NMR (C6D6): 4.49-5.60 (m,
(PhSi H)x), 6.82-7.95 (m, Ph H). 29Si NMR (C6D6): -54 to
-63. MS (EI; m/ z (relative intensity, %)): 105 (PhSi+, 100),
106 (PhSiH+, 55), 107 (PhSiH2+, 39), 133 (PhSi2+, 6), 183 (Ph2-
SiH+, 94), 210 (Ph2Si2+, 17), 240 (Ph2Si3H+, 6), 259 (Ph3Si+,
81), 266 (Ph2Si4+, 8), 287 (Ph3Si2+, 14), 316 (Ph3Si3H+, 9), 343
(Ph3Si4+, 13), 372 (Ph3Si5H+, 11), 421 (Ph4Si4H+, 12), 450 (Ph4-
Si5H2+, 15), 526 (Ph5Si5H+, 8), 634 (Ph6Si6H4+, 5), 740 (Ph7-
(η5-C5H4CH2CH2NiP r 2)2Zr (NMe2)2 (11). A solution of 210
mg (0.79 mmol) of Zr(NMe2)4 and 303 mg (1.57 mmol) of CpNH
in 15 mL of toluene was heated to gentle reflux for 5 h. All
volatile products were completly removed in vacuo (100 °C/
0.01 Torr), leaving 440 mg (0.78 mmol, 99%) of 11 as a bright
yellow oil. 1H NMR (C6D6): δ 0.99 (d, 3J ) 6.6 Hz, 24H,
CHCH3), 2.62 (m, 8H, CpCH2, NCH2), 2.91 (s, 12H, ZrNCH3),
3
2.96 (m, 4H, CHCH3), 5.88 (t, J ) 2.7 Hz, 4H, Cp H), 6.00 (t,
3J ) 2.7 Hz, 4H, Cp H). 13C NMR (C6D6): δ 21.1 (CHCH3),
32.9 (CpCH2), 47.5 (CH2N), 48.8 (CHCH3), 49.4 (ZrNCH3),
108.8, 111.0 (ring -CHd), 123.8 (ring dCCH2). MS (CI; m/ z
(relative intensity, %)]: 472 ([M - 2NHMe2]+, 0.5), 194 ([CpNH
+ H]+, 10), 178 ([CpNH - CH3]+, 5), 114 ([(iC3H7)2NCH2+], 65),
46 ([NHMe2 + H]+, 28). Anal. Calcd for C30H56N4Zr (564.02):
C, 63.88; H, 10.00; N, 9.93. Found: C, 63.69; H, 10.57; N, 8.95.
P olym er iza tion Stu d ies. Ethylene (BASF AG) was used
without further purification. Methylaluminoxane was ob-
tained from Witco (Bergkamen, Germany) as a 10 wt % toluene
solution (4.9% wt % aluminum, density ∼0.9 g/mL, average
molar mass of the MAO oligomers 900-1100 g/mol). All
polymerization reactions were performed in toluene solution
at room temperature. The ethylene polymerization reactions
took place under a pressure of 1 atm of ethylene.
Si7H5+, 6). IR (KBr): νSi-H 2090.2, 910 cm-1
.
With (C5H4CH2CH2NiP r 2)2TiBz2 (8). A 28 mg (0.05 mmol)
amount of 8 was dissolved in 5 mL of toluene. Under an argon
atmosphere 496 mg (4.60 mmol) of phenylsilane was added to
the solution. A weak evolution of gas commenced. After it
was stirred for 3 days at room temperature, the dark solution
was added to a column of Florisil. The polymer was recovered
by elution with toluene followed by vacuum evaporation of the
eluent. The product was obtained as a colorless, extremely
viscous liquid (300 mg, 61%). 1H NMR (C6D6): 4.49-5.30 (m,
(PhSi H)x), 6.88-7.75 (m, Ph H). 29Si NMR (C6D6): -58.7 to
-64.9. MS (EI; m/ z (relative intensity, %)): 105 (PhSi+, 100),
106 (PhSiH+, 32), 107 (PhSiH2+, 31), 133 (PhSi2+, 14), 183 (Ph2-
SiH+, 91), 210 (Ph2Si2+, 27), 240 (Ph2Si3H+, 31), 259 (Ph3Si+,
90), 266 (Ph2Si4+, 24), 287 (Ph3Si2+, 29), 316 (Ph3Si3H+, 31),
343 (Ph3Si4+, 30), 372 (Ph3Si5H+, 8), 421 (Ph4Si4H+, 30), 450
(Ph4Si5H2+, 14), 526 (Ph5Si5H+, 4), 634 (Ph6Si6H4+, 2), 636
(Ph6Si6H6+, 4), 742 (Ph7Si7H7+, 1). IR (KBr): νSi-H 2086.9,
E t h ylen e P olym er iza t ion St u d ies. Wit h (C5H 4CH 2-
CH2NiP r 2)2TiCl2 (2). A 22 mg (40.0 µmol) amount of 2 was
dissolved in 5 mL of toluene. Under an ethylene atmosphere
12.0 mL (20.0 mmol) of MAO was introduced. After 5 min
the clear yellow solution became turbid, and after 4 h the
polymerization was quenched by pouring the solution into
acidified methanol. The product was filtered off, washed with
water and acetone, and dried to constant weight (2.50 g):
productivity in g of PE [M]-1 [C2H4]-1 h-1, 0.16 × 105;41 Mw,
311 537; Mn, 190 12; Mw/Mn, 16.4.42
917 cm-1
.
Wit h (C5H4CH2CH2NiP r 2)2Ti(P h O)2 (10). An 88 mg
(0.142 mmol) amount of 10 was dissolved in 10 mL of toluene.
Under an argon atmosphere 1.05 g (9.90 mmol) of phenylsilane
was added to the solution. A weak evolution of gas com-
menced. After it was stirred for 3 days at room temperature,
the dark solution was added to a column of Florisil. The
polymer was recovered by elution with toluene followed by
vacuum evaporation of the eluent. The product was obtained
as a colorless, extremely viscous liquid (810 mg, 77%). 1H
NMR (C6D6): 4.49-5.17 (m, (PhSi H)x), 6.90-7.80 (m, Ph H).
29Si NMR (C6D6): -55.1 to -68.3. MS (EI; m/ z (relative
intensity, %)): 105 (PhSi+, 100), 106 (PhSiH+, 14), 107
(PhSiH2+, 25), 133 (PhSi2+, 7), 183 (Ph2SiH+, 81), 210 (Ph2-
Si2+, 9), 240 (Ph2Si3H+, 8), 259 (Ph3Si+, 86), 266 (Ph2Si4+, 28),
287 (Ph3Si2+, 10), 316 (Ph3Si3H+, 10), 343 (Ph3Si4+, 33), 372
(Ph3Si5H+, 5), 421 (Ph4Si4H+, 30), 450 (Ph4Si5H2+, 13), 526 (Ph5-
Si5H+, 3), 634 (Ph6Si6H4+, 1), 636 (Ph6Si6H6+, 1). IR (KBr):
With (C5H4CH2CH2NiP r 2)2Zr Cl2 (3). A 20.0 mg (40.0
µmol) amount of 3 was dissolved in 5 mL of toluene. Under
an ethylene atmosphere 12 mL (20.0 mmol) of MAO was
introduced. After 1 h the clear yellow solution became turbid,
and after 4 h the polymerization was quenched by pouring the
solution into acidified methanol. The product was filtered off,
washed with water and acetone, and dried to constant weight
(840 mg): productivity in g of PE [M]-1 [C2H4]-1 h-1, 0.053 ×
105;41 Mw, 230 452; Mn, 11 276; Mw/Mn, 20.4.42
P h en ylsila n e P olym er iza tion Stu d ies. With (C5H4CH2-
CH2NiP r 2)2TiMe2 (6). 30 mg (0.07 mmol) amount of 6 was
dissolved in 5 mL of toluene. Under an argon atmosphere 493
mg (4.54 mmol) phenylsilane was added to this solution.
Evolution of gas commenced. After it was stirred for 2 days
at room temperature, the solution was added to a column of
Florisil. The polymer was recovered by elution with toluene
followed by vacuum evaporation of the eluent. The product
was obtained as a colorless, extremely viscous liquid (370 mg,
76%). 1H NMR (C6D6): 4.49-5.60 (m, (PhSi H)x), 6.90-7.98
(m, Ph H). 29Si NMR (C6D6): -54 to -64. MS (EI; m/ z
(relative intensity, %)): 105 (PhSi+, 100), 106 (PhSiH+, 52),
107 (PhSiH2+, 30), 133 (PhSi2+, 4), 183 (Ph2SiH+, 7), 210 (Ph2-
νSi-H 2109, 916 cm-1
.
Ack n ow led gm en t. We thank the BASF AG for the
polyethylene analyses and for the generous gift of
ethylene. We further thank the Witco GmbH for
valuable gifts of MAO and the Fonds der Chemischen
Industrie for the doctoral fellowship of T.R.
+
Si2+, 10), 240 (Ph2Si3H+, 4), 259 (Ph3Si+ 87), 266 (Ph2Si4 9),
,
,
287 (Ph3Si2+, 9), 316 (Ph3Si3H+, 6), 343 (Ph3Si4+, 14), 372
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement details, positional and thermal
parameters, and bond distances and angles for 2 (7 pages).
Ordering information is given on any current masthead page.
(41) In the analogous polymerization reactions, the metallocene
dichloride dihydrochlorides CpN2MCl2‚2HCl (4, 5) show nearly the same
productivities as the nonprotonated metallocene dichlorides CpN2MCl2
(2, 3).
(42) Molecular weights and molecular weight destributions were
determined by BASF AG (Ludwigshafen, Germany).
OM960233S