Process for preparing bridged stereorigid metallocenes

The invention relates to a new improved process for preparing bridged stereorigid metallocenes via organomagnesium and organotin compounds.

BACKGROUND OF THE INVENTION 
The invention relates to a new and improved process for preparing bridged 
stereorigid metallocenes via organomagnesium and organotin compounds. 
Metallocenes based on cyclopentadiene, indene and fluorene are, in 
combination with specific co-catalysts such as, for example, aluminoxanes 
or tetraphenylborate complexes, highly active catalysts and with suitable 
ligand systems also form stereospecific catalyst systems for the 
polymerization of olefins. 
These catalysts, processes for their preparation and their use are 
described in detail in EP-A-0 480 390, EP-A-0 413 326, EP-A-0 530 908, 
EP-A-0 344 887, EP-A 420 436, EP-A-0 416 815, and EP-A-0 520 732. 
The compounds specified therein are largely produced in accordance with the 
reaction scheme given, for example, in EP-A-O 480 390, page 5. In this 
method, the cyclopentadienyl derivatives are metallated with lithium 
alkyls, subsequently reacted with alkyl dihalides or alkyl ditosylates to 
give the bridged ligand systems and then, in a subsequent step, reacted 
again with lithium alkyls to give the corresponding dimetallated compounds 
which then react with transition metal halides to give the bridged 
metallocenes (J. Organomet. Chem., 1985, 288, 63; J. Organomet. Chem., 
1988, 342, 21). 
These processes have a series of disadvantages: 
multistage syntheses in which the intermediates sometimes have to be 
isolated and purified, 
it is necessary to carry out individual reaction steps at temperatures 
.ltoreq.56.degree. C., 
use of solvents which are not unproblematical in terms of safety and/or 
environmental considerations, such as ether, hexamethylphosphoramide 
(HMPA), methylene chloride or chloroform, 
separation processes (e.g. extractions), particularly in the last step, 
which in combination with the material properties of the products (sparing 
solubility, extreme sensitivity to traces of air and moisture) and the 
salts to be separated off (e.g. LiCl) can only be carried out industrially 
at high cost and contribute to high losses in yield, 
control of the rac:meso ratio during the synthesis in the case of compounds 
which, owing to the ligand substitution, can in principle be formed in a 
racemate (rac) (two enantiomers) and a meso form, is not generally 
possible (hitherto the formation of the meso compound could be reduced or 
prevented only by working at -56.degree. C. in a few individual cases), 
only small yields of the desired metallocene, particularly when calculated 
over all steps. 
Therefore there is increasing interest in the provision of suitable, 
general synthetic processes, particularly also those which can be used 
without problems for industrial amounts, which are able to give such 
transition metal complexes in high yields as cheaply as possible. 
It is an object of the invention to derive synthetic processes which allow, 
while avoiding the indicated disadvantages, the preparation of bridged 
stereorigid metallocenes in high yields, as a matter of choice with or 
preferably without isolation of the intermediates, and can also be carried 
out industrially without problems. 
BRIEF SUMMARY OF THE INVENTION 
It has now been found that, using dialkylmagnesium compounds, bridged 
ligand systems can be successfully formed in high yields under 
industrially advantageous reaction conditions, and also the magnesium and 
tin derivatives of these ligand systems which are particularly suitable 
for the optimum further reactions are obtainable in yields in a 
single-vessel process and can be reacted directly to give the desired 
metallocenes. 
Furthermore, it has surprisingly been found that in reactions of ligands 
which, owing to their substitution, are suitable for the formation of the 
stereoisomeric products (racemate (rac):meso compounds), to give 
metallocenes, it is possible to influence the rac:meso product ratio 
within wide limits by means of the reaction procedure. 
One aspect of the subject matter of the invention is a process for 
preparing bridged, stereorigid metallocenes of the general formula (1) 
EQU Q(CpR.sub.a)(Cp'R'.sub.a')M(X).sub.n ( 1) 
wherein Cp is a cyclopentadienyl, an indenyl or a fluorenyl radical; 
R and R' are identical or different and each is an alkyl, alkoxy, 
phosphine, amino, alkylamino, dialkylamino, alkoxy-alkyl, arylalkyl, or 
aryloxy-alkyl group; 
0.ltoreq.a.ltoreq.4 and 0.ltoreq.a'.ltoreq.4; 
Cp' is cyclopentadienyl, indenyl, or fluorenyl, or when a' is 1, Cp' can be 
NR" wherein R" is a C.sub.1 -C.sub.12 alkyl or C.sub.6 -C.sub.10 aryl 
radical; 
Q is a single-membered or multi-membered bridge 
##STR1## 
between Cp and Cp' wherein R.sup.1 and R.sup.2 are identical or different 
and in each occurrence is a hydrogen atom, a C.sub.1 -C.sub.10 -alkyl 
group or a C.sub.6 -C.sub.10 -aryl group, Z is carbon, silicon or 
germanium, and b is 1, 2 or 3; 
M is a transition metal from any of the groups 3 to 6 of the Periodic Table 
(IU notation), in particular Zr or Hf; 
X is halogen, in particular Cl or Br; and 
n is the oxidation state of M in said compound, reduced by 2. 
Compounds of formula (1) wherein CpR.sub.a and Cp'R'.sub.a' in formula (1) 
are identical, that is, compounds of the formula Q(CPR.sub.a).sub.2 
M(X).sub.n 
are prepared by a process which comprises 
1) in a first step reacting a compound of the formula CpR.sub.a with one or 
more magnesium compounds of the formula (R.sup.3 R.sup.4).sub.c Mg, 
wherein R.sup.3 and R.sup.4 are each bonded to the Mg and are identical or 
different and each is H or a C.sub.1 -C.sub.12 -alkyl radical and c is 0 
or 1, in accordance with the general equation 
EQU 2CpR.sub.a +(R.sup.3 R.sup.4).sub.c Mg.fwdarw.(CpR.sub.a).sub.2 Mg+cR.sup.3 
H+cR.sup.4 H 
and then 
2) in a second step, reacting the reaction product of the first step with 
one or more compounds of the formula X.sup.1 QX.sup.2, wherein X.sup.1 and 
X.sup.2 are identical or different and each is Cl, Br, I or --OSO.sub.2 
R.sup.5, wherein R.sup.5 is an alkyl radical having 1-10 carbon atoms or 
an aryl radical having 6-10 carbon atoms, in accordance with the general 
equation 
EQU (CpR.sub.a).sub.2 Mg+X.sup.1 QX.sup.2 .fwdarw.(CpR.sub.a).sub.2 Q+MgX.sup.1 
X.sup.2 
and then 
3) in a third step, reacting the reaction product of the second step with 
one or more magnesium compounds of the formula (R.sup.3 R.sup.4).sub.c Mg 
in accordance with the general equation 
EQU (CpR.sub.a).sub.2 Q+(R.sup.3 R.sup.4).sub.c Mg.fwdarw.Q(CpR.sub.a).sub.2 
Mg+cR.sup.3 H+cR.sup.4 H 
and then 
4) in a fourth step, reacting the reaction product of the third step with 
one or more tin compounds of the formula R.sup.6.sub.4-k SnX.sup.3.sub.k, 
wherein R.sup.6 is a C.sub.2 -C.sub.20 -alkyl radical, in particular a 
C.sub.4 -C.sub.8 -alkyl radical, or a C.sub.6 -C.sub.10 -aryl radical, 
X.sup.3 is a halogen atom, in particular Cl or Br, and k is 1-4, in 
accordance with the general equation 
EQU Q(CpR.sub.a).sub.2 Mg+2R.sup.6.sub.4-k SnX.sup.3.sub.k 
.fwdarw.Q(CPR.sub.a).sub.2 (SnX.sup.3.sub.k-1 R.sup.6.sub.4-k).sub.2 
+MgX.sup.3.sub.2 
and then 5) in a fifth step, reacting the reaction product of the fourth 
step with a transition metal halide of the formula M(X).sub.m, where m is 
equal to the oxidation state of M, in accordance with the equation 
EQU Q(CpR.sub.a).sub.2 (SnX.sup.3.sub.k-1 R.sup.6.sub.4-k).sub.2 +M(X).sub.m 
.fwdarw.Q(CpR.sub.a).sub.2 M(X).sub.2 +2SnX.sup.3.sub.k-1 XR.sup.6.sub.4-k 
Compounds of formula (1) wherein CpRa and Cp'R'.sub.a' are not identical 
are prepared by carrying out the aforementioned third, fourth and fifth 
steps using a compound of the formula Q(CpRa)(Cp'R'.sub.a') in place of a 
compound of the formula Q(CpRa).sub.2. 
A further subject matter of the invention is characterized in that the 
reaction products of the intermediate steps are, without isolation, used 
directly for the further reaction of the respective subsequent steps. 
A further subject matter of the invention is compounds of the general 
formula 
EQU Q(CpR.sub.a)(Cp'R'.sub.a')(SnX.sup.3.sub.k-1 R.sup.6.sub.4-k).sub.2 
wherein 
Q is a single-membered or multi-membered bridge 
##STR2## 
between Cp and Cp', wherein each R.sup.1 and R.sup.2 are identical or 
different and each is a hydrogen atom, a C.sub.1 -C.sub.10 alkyl group or 
a C.sub.6 -C.sub.10 aryl group, Z is carbon, silicon or germanium, and b 
is 1, 2 or 3; 0.ltoreq.a.ltoreq.4 and 0.ltoreq.a'.ltoreq.4; 
Cp and Cp' are each a cyclopentadienyl, an indenyl or a fluorenyl radical; 
R and R' are the same or different and in each occurrence is an alkyl, 
alkoxy, phosphine, amino, alkylamino, dialkylamino, alkoxy-alkyl, 
aryl-alkyl, or aryloxy-alkyl group; 
R.sup.6 is a C.sub.2 -C.sub.20 -alkyl radical or a C.sub.6 -C.sub.10 -aryl 
radical; 
k is 1-4; and 
X.sup.3 is a halogen atom, especially Br or Cl. 
Referring to the R.sup.1 and R.sup.2 substituents, each is preferably 
C.sub.1 -C.sub.5 alkyl, particularly methyl or ethyl, or is preferably 
C.sub.6 -C.sub.8 aryl, particularly phenyl. 
Referring to the R and R' substituents, each one can be 
alkyl containing 1 to 10 carbon atoms, for example methyl and ethyl 
(including dimethyl and trimethyl); 
alkoxy containing 1 to 10 carbon atoms, for example methoxy and ethoxy 
(including dimethoxy and trimethoxy); 
alkylamino and/or dialkylamino, wherein each alkyl group contains 1 to 10 
carbon atoms, for example dimethylamino and dipropylamino (including 
bis(dimethylamino)); 
alkoxyalkyl containing a total of 2 to 20 carbon atoms; 
aryl-alkyl and/or aryloxy-alkyl groups wherein the aryl group contains 6 to 
10 carbon atoms and the alkyl portion contains 1 to 10 carbon atoms; 
phosphine, including phosphine substituted with 1 or 2 groups each of which 
is C.sub.1 -C.sub.10 alkyl or C.sub.6 -C.sub.10 aryl, for example 
diphenylphosphino. 
The further subject matter of the invention is characterized by the claims. 
DETAILED DESCRIPTION OF THE INVENTION 
The cyclopentadienyl compounds CpR.sub.a which can be used according to the 
invention for the first step 1) of the process are part of the known prior 
art and are compounds in which Cp can be a cyclopentadienyl radical or an 
indenyl radical and each of the R groups, if present, is an alkyl, 
phosphine, amino, alkylamino, dialkylamino, alkoxyalkyl, aryl-alkyl, or 
aryloxy-alkyl groups with 0.ltoreq.a.ltoreq.4. Each of the substituents R 
on the Cp radical can be identical or different. According to the 
invention, preference is given to compounds in which R represents alkyl 
radicals having 1-6 carbon atoms and a is 0 to 4. 
The compounds (R.sup.3 R.sup.4).sub.c Mg used are preferably those in which 
R.sup.3 and R.sup.4 are identical or different and each is H or a 
C.sub.1-12 alkyl radical and c is 1. According to the invention, 
preference is given to butylethylmagnesium, di-n-butylmagnesium, 
di-n-hexylmagnesium, and n-butyl-sec-butylmagnesium in their commercial 
formulations and in particular, BOMAG.RTM.-A from Witco GmbH (a mixture of 
dibutylmagnesium, dioctylmagnesium, and optionally, butyloctylmagnesium, 
in a ratio of butyl:octyl chains of 3:1, 20% strength in heptane). 
The reactions are carried out in an inert gas atmosphere such as nitrogen. 
According to the invention, the components are here preferably initially 
charged at room temperature in an inert solvent and the temperature is 
increased with vigorous stirring. 
Inert solvents which can be used are those customary in this field such as, 
for example, aliphatic or cyclic ethers or aromatic hydrocarbons. 
According to the invention, preference is given to aliphatic hydrocarbons 
having boiling points .gtoreq.60.degree. C., preferably .gtoreq.80.degree. 
C., in particular in the range of 90.degree.-120.degree.. To achieve 
practical reaction times, the reaction is preferably carried out at the 
boiling point of the solvents, in particular between 
80.degree.-120.degree. C. The concentration of the reaction mixture is 
largely non-critical. However, to achieve high space-time yields, it is 
carried out in the upper technically possible range. 
The (CpR.sub.a).sub.2 Mg compounds thus obtained are, according to the 
invention, reacted, preferably directly, in a second stage with the 
compounds X.sup.1 QX.sup.2 in accordance with the general reaction 
equation 
EQU (CpR.sub.a)Mg+X.sup.1 QX.sup.2 .fwdarw.(CpR.sub.a).sub.2 Q+MgX.sup.1 
X.sup.2 
to give the bridged biscyclopentadienyl compounds. 
The components X.sup.1 QX.sup.1 which can be used for bridging are 
compounds known from the prior art (EP-A-0 480 390, EP-A-0 413 326, EP-A-0 
530 908, EP-A-0 344 887). According to the invention, preference is given 
to compounds in which X.sup.1 and X.sup.2 are Cl, Br or --O-tosyl. 
The reaction mixture of the first step is, if desired, cooled prior to 
addition of the component X.sup.1 QX.sup.2 to below the boiling point 
thereof and after addition is complete is again heated up to the boiling 
point. 
If desired, to increase the reaction rate, ether such as preferably alkyl 
ether having, in particular, from 6 to 10 carbon atoms such as, in 
particular, di-n-butyl ether can be additionally added in at most the 
stoichiometric amount, based on magnesium. 
The reaction times are usually between 1 and 3 hours. 
In the process of the invention, the starting materials are preferably used 
in stoichiometric amounts in both steps. As a result of this and the 
almost quantitative conversion under practical conditions, the bridged 
biscyclopentadienyl compounds are formed in such purities that they can be 
used directly without workup for further reactions. 
Examples of the bridged biscyclopentadienyl compounds which can be prepared 
by the process of the invention are dimethylsilyl bis(1-indene), 
dimethylsilyl-bis (1-cyclopentadiene), 2,2-propylbis(1-indene), 
2,2-propylbis (trimethylcyclopentadiene), 2,2-propylbis 
(5-dimethylamino-1-indene), 2,2-propylbis (6-dipropylamino-1-indene), 
2,2-propylbis (4-7-bis (dimethylamino-1-indene)), 2,2-propylbis 
(5-diphenylphosphino-1-indene), 2,2-propyl-bis 
(4,5,6,7-tetrahydro-1-indene), 2,2-propylbis (4-methyl-1-indene), 
2,2-propylbis (5-methyl-1-indene), 2,2 propylbis (6-methyl-1-1-indene), 
2,2-propylbis (7-methyl-1-indene), 2,2-propylbis (5-methoxy-1-indene), 
2,2-propylbis (4,7-dimethoxy-1-indene), 2,2-propylbis 
(2,3-dimethyl-1-indene), 2,2-propylbis (4,7-dimethyl-1-indene, 
2,2-propylbis (1-cyclopentadiene), 2,2-propylbis (1-indene), 
di-phenylmethylbis (1-indene), diphenylmethylbis (1-cyclopentadiene), 
diphenylmethylbis (1-indene), diphenylsilyl-bis (1-indene), 
diphenylsilylbis (1-cyclopentadiene), diphenylsilylbis (1-indene), 
ethylenebis (1-indene), ethylenebis (trimethylcyclopentadiene), 
ethylenebis (5-dimethylamino-1-indene), ethylenebis 
(6-dipropylamino-1-indene), ethylenebis (4,7-bis 
(dimethylamino)-1-indene), ethylenebis (5-diphenylphosphino-1-indene), 
ethylenebis-(4, 5, 6, 7-tetrahydro-1-indene), ethylenebis 
(4-methyl-1-indene), ethylenebis (5-methyl-1-indene), ethylenebis 
(6-methyl-1-indene), ethylenebis (7-methyl-1-indene), ethylenebis 
(5-methoxy-1-indene), ethylenebis (4, 7-di-methoxy-1-indene), ethylenebis 
(2,3-dimethyl-1-indene), ethylenebis 4,7-dimethyl-1-indene), ethylene bis 
(9-fluorene), and ethylene bis (1-cyclopentadiene). 
According to the invention, the reaction mixture from the second step is 
reacted, preferably directly without isolation of the reaction product, in 
a third step again with one or more magnesium compounds of the formula 
(R.sup.3 R.sup.4).sub.c Mg wherein R.sup.3,R.sup.4 and c are as defined 
for step 1), in preferably stoichiometric amounts under the same reaction 
conditions as in step 1) to give the bridged magnesium compounds 
Q(CpR.sub.a).sub.2 Mg. 
Into this reaction mixture is metered a tin compound of the general formula 
R.sup.6.sub.4-k SnX.sup.3.sub.k at temperatures between about 20.degree. 
and 120.degree. C., preferably at the reaction temperature of step 3. 
In the tin compounds, R.sup.6 is preferably an alkyl radical having 2-20 
carbon atoms, in particular 4-8 carbon atoms, X.sup.3 is a halogen 
radical, in particular Cl or Br, and k is from 1 to 4. According to the 
invention, preference is given to di-n-butyltin dichloride, tri-n-butyltin 
chloride, tri-n-octyl tin chloride or di-n-octyl tin dichloride. The tin 
compound is preferably used in twice the molar amount of the magnesium 
compound. 
After the reaction is complete, after from 1 to 4 hours depending on 
reaction temperature, and after cooling to room temperature, all 
precipitated magnesium salts are separated off by the customary methods 
such as decantation, filtration and/or centrifugation. 
In the fifth step, the solids-free organic phase, which contains the 
compound Q(CpR.sub.a).sub.2 (SnX.sup.3.sub.k-1 R.sup.6.sub.4-k).sub.2 as 
reaction product, is (preferably without further workup) admixed at room 
temperature with the transition metal halide M(X).sub.m, wherein M is a 
metal of any of groups 3 to 6 of the Periodic Table of the Elements (IU 
notation), in particular Zr or Hf, X is a halogen atom, in particular Cl 
or Br, and m is equal to the oxidation state of M, and the reaction is 
carried out at from room temperature up to the boiling point of the 
solvent used, preferably 20.degree.-120.degree. C., in particular 
20.degree.-80.degree. C. The reaction is generally complete after from 1 
to 4 hours. 
The reaction of the fifth step can lead to stereo-isomeric compounds which 
are obtained in racemic and mesomeric form. For the preparation of 
catalysts for olefin polymerization, preference is given to the racemic 
compounds because of their high activity and stereo-selectivity. 
In place of the complicated processes, usual in the prior art, for 
isolating the racemates, in the process of the invention the ratio can be 
controlled in a simple manner by means of the selected concentration 
ratios alone: 
The higher the concentration of tin compound, the higher the proportion of 
racemate. 
To achieve the desired ratio of racemate (rac):meso compound, the solvent 
is, prior to the reaction with the transition metal halide, distilled off 
completely or partially, i.e. in the required amount. 
According to the invention, the process is preferably carried out without 
isolation of the reaction products of the steps 1 to 4. However, it is 
likewise possible to isolate the respective intermediates prior to the 
reaction in the subsequent step or, if desired, to prepare them in another 
way and to use them for the subsequent step. 
In the case of the unsymmetrical compounds Q(CpR.sub.a)(Cp'R'.sub.a '), in 
which CpR.sub.a is not the same as Cp'R'.sub.a ', these are prepared by 
processes known in the literature and, commencing in step 3, are reacted 
further according to the process steps 3), 4) and 5) of the invention to 
give the metallocenes. 
Unsymmetrical compounds which can be additionally used according to the 
invention are 2,2-propylbis(1-indene) (1-cyclopentadiene), 2,2-propylbis 
(1-indene) (9-fluorene), diphenylmethylbis (1-indene) (1-cyclopentadiene), 
diphenylmethylbis (1-indene) (9-fluorene), diphenylsilylbis (1-indene) 
(1-cyclopentadiene), diphenylsilylbis (1-indene) (9-fluorene), ethylenebis 
(1-indene) (1-cyclopentadiene) and ethylenebis (1-indene) (9-fluorene).

EXAMPLES 
All experiments were carried out with exclusion of oxygen and moisture 
under inert gas. 
EXAMPLE 1 
Preparation of ethylenebis (inden-1-yl) zirconium dichloride: 
a) Racemate (rac):meso=1:1 
At room temperature (RT), a mixture was prepared of 556 ml BOMAG.RTM.-A 
(0.486 mol; a mixture of butyl and octylmagnesium from Witco GmbH; 20% 
strength in heptane) and 126 ml of indene (90% strength; 0.97 mol). 
The mixture was subsequently stirred for 4 hours under reflux, until the 
cessation of gas evolution indicated completion of the reaction. 
After cooling to 70.degree. C., 41.9 ml (0.486 mol) of 1,2-dibromoethane 
and 69 ml of di-n-butyl ether were metered in. The mixture was again 
refluxed for 4 hours. 
Prior to the addition of a further 556 ml of BOMAG.RTM.-A the reaction 
mixture was cooled to RT. 
This was followed by refluxing for a further 3 hours. 
264 ml (0.97 mol) of tri-n-butyltin chloride were then added to the cooled 
mixture. 
Under reflux for a period of 2 hours, the tri-butyltin was substituted and 
magnesium chloride was eliminated. 
After separating off the inorganic salts, the clear solution obtained was 
admixed with 102 g of ZrCl.sub.4 (0.44 mol) and stirred for 1 hour at RT 
and for 3 hours at 60.degree. C. 
The crude product was then isolated by means of filtration. 
Yield: 156 g of crude product (85% of theory, based on ZrCl.sub.4 ; 
rac:meso ratio=1:1). 
Boiling with fresh heptane and stirring with THF at RT gave 55 g (30%) of 
pure rac compound (I): Ethylene (indenyl).sub.2 ZrCl.sub.2 : .sup.1 H-NMR: 
(CDCl.sub.3 ; 7.23 ppm) 7.68-7.13 (m, 8H, C.sub.6 H.sub.4); 6.58 (d, 2H, 
a-C.sub.5 H.sub.2); 6.2 (d, 2H, b-C.sub.5 H.sub.2); 3.75 (s, 4H, 
--CH.sub.2 CH.sub.2 --) Zr: calc.: 21.8%, found: 22.0%; Cl: calc.: 16.9%, 
found: 16.7% 
b) rac:meso=10:1 
The reaction was carried out in a similar way to 1 a), but with freeing the 
reaction solution of solvent (by heating up to 80.degree. C./1 torr) prior 
to the addition of the ZrCl.sub.4. 
147 g (80%) of crude product having a rac:meso ratio of 10:1 were obtained. 
After purification, 110 g (60%) of pure rac compound were isolated. 
(.sup.1 H-NMR was identical with that in 1 a); Zr: 21.9%; Cl: 16.6%). 
EXAMPLE 2 
Preparation of ethylenebis (inden-1-yl) hafnium dichloride 
a) rac:meso=2:1 
85.2 ml of indene (94% strength; 0.73 mol) were initially charged and 416 
ml of BOMAG.RTM.-A (20% strength in heptane; 0.364 mol) were metered in 
under reflux. The mixture was refluxed for 6 hours. 
31.4 ml of 1, 2-dibromoethane (0.364 mol) and 50 ml of di-n-butyl ether 
were added at 60.degree.-70.degree. C. and the mixture was allowed to 
react further for 4 hours under reflux. 
Subsequently, another 416 ml of BOMAG.RTM.-A (20% strength in heptane; 
0.364 mol) were introduced and the mixture was stirred for 4 hours under 
reflux. 
196 ml of tri-n-butyltin chloride (0.723 mol) were then metered in at 
80.degree. C. with subsequent refluxing for 4 hours. 
All inorganic salts were subsequently separated off and the clear filtrate 
was used further. 
HfCl.sub.4 (92.2 g; 0.288 mol) was introduced into the solution at 
0.degree. C. The mixture was slowly heated to 60.degree. C. After 30 
minutes the temperature was raised to reflux temperature and the reaction 
mixture was left thereat for 2 hours. 
After cooling to RT, the solid which precipitated was isolated and dried. 
110 g (92%) of crude product (II) having a rac:meso ratio of about 2:1 were 
isolated. 
Stirring with tetrahydrofuran (THF) finally gave 50.2 g (42%) of pure 
racemate of (II). 
rac-ethylene (indenyl).sub.2 HfCl.sub.2 (II): 
.sup.1 H-NMR: (CDCl.sub.3, 7.23 ppm) 7.65-7.1 (m, 8H, C.sub.6 H.sub.4); 
6.48 (d, 2H, a-C.sub.5 H.sub.2); 6.09 (d, 2h, b-C.sub.5 H.sub.2); 3.8 (s, 
4H, --CH.sub.2 CH.sub.2 --) 
Hf: calc.: 35.3%, found 35.8%; Cl: calc.: 14.02%, found: 13.9% 
b) rac:pure 
The reaction was carried out in a similar way to 2 a), but after the 
reaction with tri-n-butyltin chloride and the removal of the precipitated 
inorganic salts the solution was freed of solvent by distillation with the 
application of vacuum. 
The crude product obtained after reaction with HfCl.sub.4 contained no meso 
compound. 
After purification, 73.5 g (61% of theory; based on HfCl.sub.4) of pure 
(II) were obtained by means of filtration and drying. 
.sup.1 H-NMR identical with that in 3 a); Hf: found 35.5% Cl: found 14.0% 
EXAMPLE 3 
Preparation of Me.sub.2 Si-bis(inden-1-yl) zirconium dichloride 
a) rac:meso=1.1:1 
55.7 ml of indene (95% strength; 0.454 mol) and 50 ml of heptane were 
initially charged and admixed over a period of 15 minutes under reflux 
with 260 ml of BOMAG.RTM.-A (20% strength in heptane; 0.227 mol). After 
refluxing for 3 hours, the mixture was cooled to RT. 
29.3 g of dimethydichlorosilane (0.227 mol), 39 ml of di-n-butyl ether and 
25 ml of hexane were then metered into the reaction solution and the 
mixture was refluxed for 3 hours. 
After adding further BOMAG.RTM.-A (260 ml; 0.227 mol), boiling for 4 hours 
under reflux and cooling to RT, 123 ml of tri-n-butyltin chloride were 
metered in while stirring (the temperature rose to 45.degree. C.) and the 
reaction was continued for 4 hours at 50.degree. C. 
The precipitated salts were separated off and the clear filtrate was 
admixed with 47.6 g of ZrCl.sub.4 (0.204 mol). 
The mixture was stirred for 2 hours at RT and for 1 hour under reflux. 
Filtration and drying gave 79.7 g of crude product (87% of theory; based on 
ZrCl.sub.4) having a rac:meso ratio of 1.1:1. 
Purification gave a yield of pure rac product (III) of 28.4 g (31%). 
rac-Me.sub.2 Si(indenyl).sub.2 ZrCl.sub.2 (III): 
.sup.1 H-NMR:(CDCl.sub.3, 7.23 ppm) 7.62-7.03 (m, 8H, C.sub.6 H.sub.4 ; 
6.94 (d, 2H, a-C.sub.5 H.sub.2); 6.1 (d, 2H, b-C.sub.5 H.sub.2); 1.13 (s, 
6 H, Si(CH.sub.3).sub.2) Zr: calc.: 20.3%, found: 20.3%; Cl: calc.: 15.8%, 
found: 15.7% 
b) pure racemate: 
522 ml of BOMAG.RTM.-A (20% strength; 456.6 mmol) were initially charged 
and heated to reflux. 121 ml of indene (90% strength: 931.2 mmol) were 
then metered in over a period of 30 minutes with subsequent refluxing for 
4 hours. 
At RT, 55.3 ml of Me.sub.2 SiCl.sub.2 (456 mmol), 80 ml of di-n-butyl ether 
and 40 ml of hexane were then added thereto. This was followed by 
refluxing for 2 hours. 
After addition of 522 ml of BOMAG.RTM.-A and further reaction for 4 hours 
under reflux, tri-n-butyltin chloride (253 ml, 931 mmol) was metered in at 
RT and the mixture left at 50.degree. C. for 4 hours. 
The reaction solution was freed of the precipitated salts and volatile 
constituents were separated off by distillation (up to 100.degree. C.; 1 
torr). 
98 g of ZrCl.sub.4 (420 mmol) were introduced at 20.degree. C. into the 
viscous, clear solution. The mixture was stirred for 2 hours at 90.degree. 
C. 
149 g of crude product (79% of theory; based on ZrCl.sub.4), still 
containing small amounts of impurities but no meso compound, were 
obtained. 
After purification, 122 g of pure rac (III) (65% of theory) were obtained. 
.sup.1 H-NMR identical with that in 3 a) Zr: found: 20.4% Cl: found 15.6% 
EXAMPLE 4 
Industrial preparation of Me.sub.2 Si(indenyl).sub.2 ZrCl.sub.2 : 
7.95 kg of indene (90% strength) were initially charged into a 150 liter 
reactor and admixed with 27.05 kg of BOMAG.RTM.-A (1.2 mol/kg). 
After heating to reflux (98.degree. C.), the mixture was left for 3 hours 
at this temperature, until butane gas evolution had finished. 
A solution of 4.24 kg of dichlorodimethylsilane and 4.23 kg of di-n-butyl 
ether in 4 liters of hexane was then metered at about 70.degree. C. into 
the suspension obtained. This was followed by further reaction for 2 hours 
under reflux. 
Immediately afterwards, a further 27.05 kg of BOMAG.RTM.-A was added with 
subsequent refluxing for 3 hours. 
21.14 kg of tri-n-butyltin chloride were then metered in and the mixture 
was stirred for 3 hours at 50.degree. C. 
The precipitated magnesium salt was separated off by means of filtration 
and the filtrate was freed of solvent. 
The remaining viscous solution was admixed, starting at RT, with 6.96 kg of 
zirconium tetrachloride and refluxed for a further 3 hours. 
The crude product was subsequently isolated by means of filtration (pure 
rac compound; no meso compound detectable; crude yield 90%). 
For further purification, the product was stirred further with THF, so that 
75% (9.8 kg of clean rac-Me.sub.2 Si(indenyl).sub.2 ZrCl.sub.2) were 
finally obtained. 
EXAMPLE 5 
Preparation of Me.sub.2 Si-bis(inden-1-yl)hafnium dichloride: 
a) rac:meso=2:1 
148.6 ml of BOMAG.RTM.-A (20% strength in heptane; 130 mmol and 33.8 ml of 
indene (90% strength; 260 mmol) were mixed together and refluxed for 4 
hours. 
15.8 ml of Me.sub.2 SiCl.sub.2 (130 mmol), 20 ml of hexane and 20 ml of 
di-n-butyl ether were subsequently added at 20.degree. C. The mixture was 
then refluxed for 3 hours. 
The reaction mixture thus obtained was admixed with a further 148.6 ml of 
BOMAG.RTM.-A and refluxed for 3 hours, after which 70.5 ml of 
tri-n-butyltin chloride (260 mmol) were metered in at RT and the reaction 
was continued for a further 3 hours at 50.degree. C. while stirring. 
After removing the precipitated solids, the clear solution obtained was 
admixed with 37.5 g of HfCl.sub.4 (117 mmol) and refluxed for 2 hours. 
Filtration gave 44.5 g of crude product (IV) (71% of theory, based on 
HfCl.sub.4) having a rac:meso ratio of 2:1. 
Me.sub.2 Si(indenyl).sub.2 HfCl.sub.2 (IV) 
.sup.1 H-NMR: (CDCl.sub.3, 7.23 ppm) 7.58-7.03 (m, 8H, C.sub.6 H.sub.4); 
6.8 (d, 2H, C.sub.5 H.sub.2); 6.05 (d, 2H, C.sub.5 H.sub.2 ; 1.1 s, 6H, 
Si(CH.sub.3).sub.2) Hf: calc.: 33.3%, found: 33.6%; Cl: calc.: 13.2%, 
found: 13.0% 
b) pure racemate: 
The reaction was carried out in a similar manner to Experiment 5 a), except 
that the reaction solution was freed of the solvent (heated up to 
120.degree. C./1 torr) prior to the addition of the HfCl.sub.4. 
This gave a meso-free crude product which, after purification, gave 43.9 g 
(70% of theory) of pure rac-metallocene (IV). 
.sup.1 H-NMR identical with that in 6 a) Hf: found: 33.4%; Cl: found: 13.3% 
EXAMPLE 6 
Use of further dialkylmagnesium compounds: 
a) The process steps in Example 3 a) were repeated, but using 
dibutylmagnesium (1 molar in heptane) in place of BOMAG.RTM.-A. The reflux 
times during the reaction of the dialkylmagnesium were here extended by 30 
minutes in each case. 
68 g of crude product Me.sub.2 Si(indenyl) 2rCl.sub.2 (having a rac:meso 
ratio of 1:1) was obtained. 
b) Example 3 a) was carried out using dihexylmagnesium (1 molar in 
heptane). 
70 g of crude product Me.sub.2 Si (indenyl).sub.2 ZrCl.sub.2 (having a 
rac:meso ratio of 1:1) was obtained. 
EXAMPLE 7 
Isolation and characterization of the intermediate ethylene(indenyl).sub.2 
(tri-n-butyltin).sub.2 : 
10 g of indene (95% strength, 82 mmol) were admixed with 34.2 g of 
BOMAG.RTM.-A (20% strength in heptane; 41 mmol) and heated under reflux 
for 4 hours 
7.7 g (41 mmol) of 1,2-dibromoethane and 5.3 g (41 mmol) of n-butyl.sub.2 O 
were then added at room temperature and the mixture was again stirred for 
3 hours under reflux. 
The precipitated MgBr.sub.2 was subsequently separated off by means of 
filtration. 
The filtrate was admixed with 34.2 g of BOMAG.RTM.-A (20% strength in 
heptane; 41 mmol) and refluxed for 4 hours. 
26.8 g (82 mmol) of tri-n-butyltin chloride were subsequently added at 
50.degree. C. and the mixture was refluxed for a further 2 hours. 
The precipitated MgCl.sub.2 was separated off by filtration and the 
filtrate was evaporated to dryness (up to 100.degree. C./0.1 mbar). 
This gave Et(indenyl).sub.2 TBT.sub.2 (TBT=tri-n-butyl tin) in the form of 
a viscous oil in quantitative yield. 
.sup.1 H-NMR: (CDCl.sub.3) 7.55 (m, 2H); 7.45 (m, 2H); 7.3-7.1 (m, 4H); 6.5 
(d, 2H), 4.02 (m, 2H); 3.02 (s, 4H); 1.7-1.1 (m, 36 H); 0.9-0.7 (m, 8 H). 
EXAMPLE 8 
Isolation and characterization of the intermediate compound Me.sub.2 
Si(indenyl).sub.2 TBT.sub.2. 
12.2 g of indene (95% strength; 0.1 mol) were admixed with 41 g of 
BOMAG.RTM.-A (20% strength in heptane; 50 mmol) and refluxed for 4 hours. 
6.45 g of Me.sub.2 SiCl.sub.2 (50 mmol) and 6.5 g of n-butyl.sub.2 O (50 
mmol) were subsequently added at room temperature and the mixture was 
again refluxed for 2 hours. 
100 mmol (32.8 g) of tri-n-butyltin chloride were then added, the mixture 
was stirred under reflux for 2 hours, cooled, filtered and the filtrate 
was evaporated to dryness (100.degree. C./0.1 mbar). 
This gave Me.sub.2 Si(indenyl).sub.2 TBT.sub.2 as a viscous oil in 
quantitative yield. 
.sup.1 H-NMR: (CDCl.sub.3) 7.6-7.3 (m); 7.2-6.9 (m); 4.25 (s, 2H); 1.8-1.1 
(m, 36 H); 0.9-0.7 (m, 18 H); 0.5 (s, 6 H). 
EXAMPLE 9 
a) Isolation and characterization of the compound Me.sub.2 Si[Me.sub.4 
Cp)(tert-BuN)] (tri-n-butyltin).sub.2 : 13.25 g (53 mmol) of Me.sub.2 
Si[(Me.sub.4 CpH)(tert-BuSH)] 
(Literature: Organometallics, 1990, 9, 867) were added to 63.6 ml of 
BOMAG.RTM.-A (53 mmol) and the mixture was refluxed for 3 hours. 
The solution was subsequently cooled to -40.degree. and a solid 
precipitated which was isolated (13.9 g). Me.sub.2 Si[(Me.sub.4 
Cp)(tert-BuN)]Mg: 
.sup.1 H-NMR: (DMSO) 1.99 (s, 6 H, b-Me.sub.2 Cp); 1.79 (s, 6 H, a-Me.sub.2 
Cp); 1.09 (s, 9 H, Me.sub.3 C); 0.12 (s, 6 H, SiMe.sub.2) 
10 g of Me.sub.2 Si[(Me.sub.4 Cp)(tert-BuN)]Mg (36.5 mmol) were dissolved 
in 50 ml of xylene and admixed with tri-n-butyltin chloride (73 mmol; 23.8 
g) and the mixture was refluxed for 5 hours. 
The xylene was drawn off from the solution obtained after filtration and 
the remaining viscous oil was analyzed by means of NMR spectroscopy, 
.sup.1 H-NMR: (CDCl.sub.3) 1.98 (s, 6H, a-Me.sub.2 Cp); 1.82 (s, 6 H, 
Me.sub.2 Cp); 1.7-1.6 (m, 12 H, Sn--CH.sub.2 --); 1.43-1.1 (m, 24 H, 
--CH.sub.2 CH.sub.2 --); 1.06 (s, 9 H, Me.sub.3 C); 0.95 (t, 18 H, H.sub.3 
C--); 0.09 s, 6 H, Me.sub.2 Si).