Carbon and/or silicon bridged binuclear metallocene catalyst for styrene polymerization

An alkylene and/or silylene bridged binuclear metallocene catalyst for styrene polymerization is represented by the following formula (I): ##STR1## where M.sup.1 and M.sup.2 are the same or different transition metal of Group IVb of the Periodic Table; Cp.sup.1 and Cp.sup.2 are the same or different cyclopentadienyl; alkyl, alkoxy, silyl or halogen substituted cyclopentadienyl; indenyl; alkyl, alkoxy, silyl or halogen substituted indenyl; fluorenyl; or alkyl, alkoxy, silyl or halogen substituted fluorenyl, which is capable of .pi.-electron, .eta..sup.5 -bonding with M.sup.1 or M.sup.2 ; each of E.sup.1, E.sup.2 and E.sup.3, independently of one another, is a carbon atom or a silicon atom; m, p and q are integers of 0 to 15 and m+p+q.gtoreq.1; each of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6, independently of one another, is a hydrogen, an alkyl, an aryl, an alkoxy or a halogen; X is a hydrogen, an alkyl, an alkoxy or a halogen; and n is 3. M.sup.1 and M.sup.2 may also be in cardin form by mixture of (I) with a compound which abstructs an X gray from each metal atom and substitution then with non-coordinating anions.

FIELD OF THE INVENTION 
The present invention relates to carbon and/or silicon bridged binuclear 
metallocene catalysts for polymerization of styrene. More particularly, 
the present invention relates to alkylene bridged binuclear metallocene 
(ABBM) catalysts, silylene bridged binuclear metallocene (SBBM) catalysts 
and alkylene-silylene bridged binuclear metallocene (A-SBBM) catalysts for 
preparing a syndiotactic polystyrene, and to methods for preparing the 
catalysts. The present invention also includes a process for preparing a 
syndiotactic polystyrene using the ABBM, SBBM or A-SBBM catalyst through 
homopolymerization, copolymerization or terpolymerization of styrene. 
BACKGROUND OF THE INVENTION 
A number of metallocene catalysts have been developed and widely used for 
preparing a polystyrene having high stereoregularity or a polyolefin 
having good physical properties. The conventional metallocene catalysts 
have a sandwich type structure comprising a compound of a transition metal 
of Group IVb of the Periodic Table and a ligand having one or two 
cycloalkanedienyl groups such as cyclopentadienyls, indenyls and 
fluorenyls. The metallocene catalysts are usually employed with a 
co-catalyst in a polymerization process. An illustrative co-catalyst is an 
alkylaluminoxane, i.e., methylaluminoxane, which is a reaction product of 
an alkylaluminum compound with water. Syndiotactic or isotactic 
polystyrenes having stereoregularity can be produced by using the 
metallocene catalysts. In this area of stereotype polystyrenes, 
syndiotactic polystyrenes alternatively having benzene rings on the main 
chain of the polymers are significant in that the polymers have excellent 
physical properties such as heat resistance, since the polymers have a 
melting point (T.sub.m) of about 270.degree. C. due to more 
stereoregularity than amorphous isotactic polystyrenes. 
European Patent Publication No. 210 615 A2 discloses a styrene polymer 
having stereoregularity and metallocene catalysts such as cyclopentadienyl 
trichlorotitanes and alkyl-substituted cyclopentadienyl trichlorotitanes. 
It is known that the metallocene catalysts of the European Patent have 
good catalyst activity, molecular weight distribution and syndiotactic 
index. 
Japanese Patent Laid-Open Nos. 63-191811 and 03-250007 disclose a sulfur 
bridged metallocene catalyst. However, the catalyst has a disadvantage in 
that the yield of the catalyst is very low. Although various alkyl bridged 
metallocene catalysts are disclosed in Japanese Laid-Open Nos. 03-258812, 
04-275313 and 05-105712, the metallocene catalysts are disadvantageous in 
low yield of the catalysts. 
In order to overcome the shortcomings of the conventional metallocene 
catalysts, the present inventors have developed alkylene bridged binuclear 
metallocene (ABBM) catalysts, silylene bridged binuclear metallocene 
(SBBM) catalysts and alkylene-silylene bridged binuclear metallocene 
(A-SBBM) catalysts for preparing a syndiotactic polystyrene, method for 
preparing the catalysts, and a process for preparing syndiotactic 
polystyrene using the catalysts. 
OBJECTS OF THE INVENTION 
An object of this invention is to provide an alkylene and/or silylene 
bridged binuclear metallocene catalyst having a good catalyst activity for 
polymerization of styrene. 
Another object of the invention is to provide an alkylene and/or silylene 
bridged metallocene catalyst for preparing a syndiotactic polystyrene 
having a high stereoregularity, a high melting point, a high crystallizing 
temperature, and a good molecular weight distribution. 
A further object of the invention is to provide a process for preparing an 
alkylene and/or silylene bridged binuclear metallocene catalyst for 
polymerization of styrene. 
A still further object of the invention is to provide a process for 
preparing a syndiotactic polystyrene using the alkylene and/or silylene 
bridged binuclear metallocene catalyst through homopolymerization, 
copolymerization or terpolymerization of styrene. 
These and other objects and advantages may be found in various embodiments 
of the present invention. It is not necessary that each and every object 
or advantage be found in all embodiments of the present invention. It is 
sufficient that the present invention may be advantageously employed. 
Other objects and advantages of this invention will be apparent from the 
ensuing disclosure and appended claims. 
SUMMARY OF THE INVENTION 
The carbon and/or silicon bridged binuclear metallocene catalyst according 
to the present invention has a sandwich type structure in which same or 
different two compounds selected from the group consisting of an 
.eta..sup.5 -bonding, .pi.-electron cyclopentadienyl; an alkyl, alkoxy, 
silyl or halogen substituted cyclopentadienyl; and indenyl; an alkyl, 
alkoxy, silyl or halogen substituted indenyl; a fluorenyl; and an alkyl, 
alkoxy, silyl or halogen substituted fluorenyl, which are bonded to a 
transition metal of Group IVb of the Periodic Table, are bridged with an 
alkylene compound, a silylene compound or an alkylene-silylene compound. 
The metallocene catalyst includes a neutral compound of the catalyst and a 
cationic compound of the catalyst. 
The carbon and/or silicon bridged binuclear metallocene catalyst according 
to the present invention is prepared by (1) providing an alkali metal 
compound of an .eta..sup.5 -bonding, .pi.-electron cyclopentadienyl; an 
alkyl, alkoxy, silyl or halogen substituted cyclopentadienyl; an indenyl; 
an alkyl, alkoxy, silyl or halogen substituted indenyl; a fluorenyl; and 
an alkyl, alkoxy, silyl or halogen substituted fluorenyl, (2) reacting the 
alkali metal compound with an alkylene compound, a silyl compound or an 
alkylene-silylene compound, thereby producing an alkyl bridged compound, a 
silylene bridged compound or an alkylene-silylene bridged compound of same 
or different two groups of a cyclopentadienyl; an alkyl, alkoxy, silyl or 
halogen substituted cyclopentadienyl; an indenyl; an alkyl, alkoxy, silyl 
or halogen substituted indenyl; a fluorenyl; and an alkyl, alkoxy, silyl 
or halogen substituted fluorenyl, (3) reacting the bridged compound with 
an alkali metal or thallium compound having an alkyl or alkoxy group, 
thereby producing a salt state compound of the bridged compound, and (4) 
reacting the salt state compound of the bridged compound with a transition 
metal compound of Group IVb of the Periodic Table. In the method above, 
trimethylsilane or tert-butyl titanium can be added to the salt state 
compound of the bridged compound before the salt state compound is reacted 
with a transition metal compound. 
The present invention also includes a process for preparing a syndiotactic 
polystyrene using the ABBM, SBBM or A-SBBM catalyst through 
homopolymerization, copolymerization or terpolymerization of styrene. 
DETAILED DESCRIPTION OF THE INVENTION 
The carbon and/or silicon bridged binuclear metallocene catalyst according 
to the present invention has a sandwich type structure in which same or 
different two compounds selected from the group consisting of an 
.eta..sup.5 -bonding, .pi.-electron cyclopentadienyl; and alkyl, alkoxy, 
silyl or halogen substituted cyclopentadienyl; an indenyl; an alkyl, 
alkoxy, silyl or halogen substituted indenyl; a fluorenyl; and an alkyl, 
alkoxy, silyl or halogen substituted fluorenyl, which are bonded to a 
transition metal of Group IVb of the Periodic Table, are bridged with an 
alkyl compound, a silyl compound or an alkyl-silyl compound. The carbon 
and/or silicon bridged binuclear metallocene catalyst according to the 
present invention is represented by the following formula (I) or (II): 
##STR2## 
wherein M.sup.1 and M.sup.2 are the same or different transition metal of 
Group IVb of the Periodic Table such as titanium, zirconium or hafnium; 
Cp.sup.1 and Cp.sup.2 are the same or different cyclopentadienyl; alkyl, 
alkoxy, silyl or halogen substituted cyclopentadienyl; indenyl; alkyl, 
alkoxy, silyl or halogen substituted indenyl; fluorenyl; or alkyl, alkoxy, 
silyl or halogen substituted fluorenyl, which is capable of .pi.-electron, 
.eta..sup.5 -bonding with M.sup.1 or M.sup.2 ; each of E.sup.1, E.sup.2 
and E.sup.3, independently of one another, is a carbon atom or a silicon 
atom; m, p and q are integers of 0 to 15 and m+p+q.gtoreq.1; each of 
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6, independently of 
one another, is a hydrogen, an alkyl, an aryl, an alkoxy or a halogen; X 
is a hydrogen, an alkyl, an alkoxy or a halogen; n is 3; and Z is a 
non-coordinating anion represented by the formula [BQ.sub.1 Q.sub.2 
Q.sub.3 Q.sub.4 ].sup.-, where B is a boron having +3 valence, each of 
Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4, independently of one another, is a 
radical selected from the group consisting of a hydride, a dialkylamido, 
an alkoxide, an aryl oxide and a hydrocarbyl. 
The alkylene bridged binuclear metallocene (ABBM) catalysts, silylene 
bridged binuclear metallocene (SBBM) catalysts and alkylene-silylene 
bridged binuclear metallocene (A-SBBM) catalysts according to the present 
invention are prepared as set forth below. 
The carbon and/or silicon bridged binuclear metallocene catalyst according 
to the present invention is prepared by (1) providing an alkali metal 
compound of an .eta..sup.5 -bonding, .pi.-electron cyclopentadienyl; an 
alkyl, alkoxy, silyl or halogen substituted cyclopentadienyl; an indenyl; 
an alkyl, alkoxy, silyl or halogen substituted indenyl; a fluorenyl; and 
an alkyl, alkoxy, silyl or halogen substituted fluorenyl, (2) reacting the 
alkali metal compound with an alkylene compound, a silyl compound or an 
alkylene-silylene compound, thereby producing an alkyl bridged compound, a 
silylene bridged compound or an alkylene-silylene bridged compound of same 
or different two groups of a cyclopentadienyl; an alkyl, alkoxy, silyl or 
halogen substituted cyclopentadienyl; an indenyl; an alkyl, alkoxy, silyl 
or halogen substituted indenyl; a fluoroenyl; and an alkyl, alkoxy, silyl 
or halogen substituted fluorenyl, (3) reacting the bridged compound with 
an alkali metal or thallium compound having an alkyl or alkoxy group, 
thereby producing a salt state compound of the bridged compound, and (4) 
reacting the salt state compound of the bridged compound with a transition 
metal compound of Group IVb of the Periodic Table. In the method above, 
trimethylsilane or tert-butyl titanium can be added to the slat state 
compound of the bridged compound before the salt state compound is reacted 
with a transition metal compound. 
In the first step, the alkali metal compound is an alkali metal-containing 
cyclopentadienyl, an alkali metal-containing indenyl, or an alkali 
metal-containing fluorenyl. The cyclopentadienyl, indenyl and fluorenyl 
include an alkali metal-containing cyclopentadienyl, an alkali 
metal-containing indenyl, and an alkali metal-containing fluorenyl, which 
are substituted with an alkyl, an alkoxy, a silyl or a halogen. 
The alkali metal compound reacts with an alkylene compound, a silylene 
compound or an alkylene-silylene compound as in the following equation 
(III): 
##STR3## 
wherein G is a halogen atom such as fluorine, chlorine, bromine and iodine 
or a group selected from the group consisting of a methane sulfonyl, a 
benzene sulfonyl, a para-toluene sulfonyl and an acetyl, T is an alkali 
metal, and others are the same as defined above. 
In case that Cp.sup.1 and Cp.sup.2 are different each other in the equation 
(III), Cp.sup.- T.sup.+ is reacted first and then Cp.sup.- T.sup.+ is 
reacted. 
Illustrative examples of the alkylene compound in the equation (III) are 
dibromomethane, 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane, 
1,5-dibromopentane, 1,6-dibromohexane, 1,7-dibromoheptane, 
1,8-dibromooctane, 1,9-dibromononane, 1,10-dibromodecane, 
1,11-dibromoundecane, 1,12-dibromododecane, 1,13-dibromotridecane, 
1,14-dibromotetradecane and 1,15-dibromopentadecane. The bromine atom of 
the alkyl compounds may be substituted with a halogen of a fluorine, a 
chlorine and an iodine or a group selected from the group consisting of a 
methane sulfonyl, a benzene sulfonyl, a para-toluene sulfonyl and an 
acetyl. 
Illustrative examples of the silylene compound in the equation (III) are 
chlorodimethyldisilane, dichloromethylsilane, dichlorosilane, 
1,2-dichlorotetramethyldisilane, 1,3-dichlorohexsamethyldisilane, and 
1,4-dichlorooctamethyldisilane. The chlorine atom of the silyl compounds 
may be substituted with a halogen of a fluorine, a bromine and an iodine 
or a group selected from the group consisting of a methane sulfonyl, a 
benzene sulfonyl, a para-toluene sulfonyl and an acetyl. 
Illustrative examples of the alkylene-silylene compound in the equation 
(III) are 1,2-bis(chlorodimethylsilyl)ethane, 
1,3-bis(chlorodimethylsilyl)-propane, 1,4-bis(chlorodimethylsilyl)butane, 
1,5-bis(chlorodimethylsilyl)-pentane, 1,6-bis(chlorodimethylsilyl)hexane, 
1,7-bis(chlorodimethylsilyl)-heptane, 1,8-bis(chlorodimethylsilyl)octane, 
1,9-bis(chlorodimethylsilyl)-nonane, 1,10-bis(chlorodimethysilyl)decane, 
1,11-bis(chlorodimethylsilyl)-undecane, 
1,12-bis(chlorodimethylsilyl)dodecane, 
1,13-bis(chlorodimethyl-silyl)tridecane, 
1,14-bis(chlorodimethylsilyl)tetradecane, 
1,15-bis(chlorodimethylsilyl)pentadecane, bis(chloromethyl)dimethylsilane, 
bis(chloroethyl)dimethylsilane, bis(chloropropyl)dimethylsilane, 
bis(chlorobutyl)dimethylsilane, bis(chloropentyl)dimethylsilane, 
bis(chlorobutyl)dimethylsilane, bis(chloropentyl)dimethylsilane, 
bis-(3-chloroethyl)dichlorosilane), bis-(3-chloropropyl)dichlorosilane, 
bis-3-chlorobutyl)dichlorosilane, bis-(3-chloropentyl)dichlorosilane, 
bis-(3-chlorohexyl)dichlorosilane, bis-(3)-chloroheptyl)dichlorosilane, 
bis-(3-chloroocytl)dichlorosilane, 1,2-bis(trichlorosilyl)ethane, 
1,3-bis(trichlorosilyl)propane, 1,4-bis(trichlorosilyl)butane, 
1,5-bis(trichlorosilyl)pentane, 1,6-bis(trichlorosilyl)hexane, 
1,7-bis(trichlorosilyl)heptane, 1,8-bis(trichlorosilyl)octane, 
1,9-bis(trichlorosilyl)octane and 1,10-bis(trichlorosilyl)decane. The 
chlorine atom of the alkylene-silylene compounds may be substituted with a 
fluorine, a bromine or an iodine. 
The alkali metal compound in the following equation (III) is a ligand 
containing an alkali metal. Representative examples of the alkali metal 
compound are a Na-cyclopentadienide; an alkyl, alkoxy, silyl or halogen 
substituted Na-cyclopentadienide; a Na-indenide; an alkyl, alkoxy, silyl 
or halogen substituted Na-indenide; a Na-fluorenide; and an alkyl, alkoxy, 
silyl or halogen substituted Na-fluorenide. The natrium atom of the alkyl 
metal compound may be substituted with a lithium, a potassium or a 
thallium. 
The reaction by equation (III) produces an alkylene bridged compound, a 
silylene bridged compound or an alkylene-silylene bridged compound of same 
or different two groups of a cyclopentadienyl; an alkyl, alkoxy, silyl or 
halogen substituted cyclopentadienyl; an indenyl; an alkyl, alkoxy, silyl 
or halogen substituted indenyl; a fluorenyl; and an alkyl, alkoxy, silyl 
or halogen substituted fluorneyl. 
In the third step, the bridged compound reacts with an alkali metal or 
thallium compound having an alkyl or alkoxy group as in the following 
equation (IV): 
##STR4## 
wherein R' is an alkyl or an alkoxy, and T is an alkali metal or a 
thallium. Representative Examples of the alkali metal or thallium compound 
having an alkyl or alkoxy group are a butyl lithium, a sec-butyl lithium, 
a tert-butyl lithium, a methyl lithium, a Na-methoxide, a Na-ethoxide and 
a thallium ethoxide. 
The reaction by equation (IV) produces a salt state compound of an alkylene 
bridged compound, a silylene bridged compound or an alkylene-silylene 
bridged compound of same or different two groups of a cyclopentadienyl; an 
alkyl, alkoxy, silyl or halogen substituted cyclopentadienyl; an indenyl; 
an alkyl, alkoxy, silyl or halogen substituted indenyl; a fluorenyl; and 
an alkyl, alkoxy, silyl or halogen substituted fluorenyl. 
In the fourth step, the salt state compound of the bridged compound reacts 
with a transition metal compound of Group IVb of the Periodic Table as in 
the following equation (V): 
##STR5## 
wherein M.sup.1, M.sup.2 and X are the same as defined above. 
The transition metal compound of Group IVb of the Periodic Table in 
equation (V) is a compound in which a transition metal is bonded to one or 
more groups selected from the group consisting of a hydrogen, an alkyl, an 
aryl, a silyl, an alkoxy, an aryloxy, a siloxy and a halogen. Illustrative 
examples of the transition metal compound are titanium tetrachloride, 
zirconium tetrachloride and hafnium tetrachloride. 
In case that M.sup.1 and M.sup.2 are different each other in the equation 
(V), M.sup.1 X.sub.n is reacted first and then M.sup.2 X.sub.n is reacted. 
In the method above, trimethylsilane or tert-butyl titanium can be added to 
the salt state compound of the bridged compound before the salt state 
compound is reacted with a transition metal compound. 
The product of the equation (V) is a binuclear metallocene catalyst 
represented by the general formula (I) above. The metallocene catalyst 
represented by the general formula (II) above is prepared by bonding a 
non-coordinating anion to the metallocene catalyst of the general formula 
(I). 
The alkylene and/or silylene bridged binuclear metallocene catalyst of the 
general formula (I) or (II) is supported on a support for polymerization 
of styrene. In other words, the metallocene catalyst is supported on a 
dehydrated supporter. Exemplary supports are silica, alumina, magnesium 
chloride, zeolite, aluminum phosphate and zirconia. The support can be 
activated with a non-aluminum co-catalyst or an organometallic compound. 
Exemplary non-aluminum co-catalysts useful in this invention are [R.sub.7 
R.sub.8 R.sub.9 Cl].sup.+ [BQ.sub.1 Q.sub.2 Q.sub.3 Q.sub.4 ].sup.- and 
[HNR.sub.10 R.sub.11 R.sub.12 ].sup.+ [BQ.sub.1 Q.sub.2 Q.sub.3 Q.sub.4 
].sup.-, wherein R.sub.7 .about.R.sub.12, independently of one another, 
are a hydrogen, an alkyl, an aryl, an alkoxy, a silyl or a siloxy, B is a 
boron having +3 valence, and each of Q.sub.1, Q.sub.2, Q.sub.3 and 
Q.sub.4, independently of one another, is a radical selected from the 
group consisting of a hydride, a dialkylamido, an alkoxide, an aryl oxide 
and a hydrocarbyl. Exemplary organometallic compounds are an 
alkylaluminoxane or an organoaluminum compound. Illustrative examples of 
the alkylaluminoxane are a methylaluminoxane (MAO) and a modified 
methylaluminoxane (MMAO), and an illustrative example of the 
organoaluminum compound is AlR.sub.n X.sub.3-h, wherein R is an alkyl or 
aryl havig C.sub.1 -C.sub.10, X is a halogen, and n is an integer of 1-3. 
Syndiotactic polystyrene is prepared using an alkylene and/or silylene 
bridged binuclear metallocene catalyst of this invention. Syndioactic 
polystyrene is prepared using the ABBM, SBBM or A-SBBM catalyst of this 
invention through homopolymerization, copolymerization or 
terpolymerization of styrene. Homopolymerization of styrene means 
polymerization of styrene monomers or monomers of a styrene derivative. 
Examples of the styrene derivative usable in this invention are an 
.alpha.-methyl styrene, a para-methyl styrene, an .alpha.-chlorostyrene 
and a para-chlorostyrene. Copolymerization of styrene means polymerization 
of any two selected from styrene monomers, monomers of styrene 
derivatives, .alpha.-olefin monomers and polar monomers. Examples of the 
.alpha.-olefin monomers usable in this invention are an ethylene, a 
propylene, a butene, a butadiene, a polybutadiene, a hexene and an octene. 
Examples of the polar monomers are a methyl methacrylate (MMA), 
acrylonitrile (AN), vinylacetate (VA) and vinylchloride monomer (VCM). 
Terpolymerization of styrene means polymerization of any three monomers 
selected from styrene monomers, monomers of styrene derivatives, 
.alpha.-olefin monomers and polar monomers. 
The catalyst is used in the amount of 10.sup.-7 .about.10.sup.-3 mol per 1 
l of solvent, preferably in amount of 10.sup.-6 .about.10.sup.4 mole. The 
polymerization temperature is 0.about.100.degree. C., preferably 
30.about.60.degree. C. 
The invention may be better understood by reference to the following 
examples which are intended for purposes of illustration and are not to be 
construed as in any way limiting the scope of the present invention, which 
is defined in the claims appended hereto.

EXAMPLES 
The following Examples 1-6 are carried out to prepare the catalysts in 
accordance with the present invention, the following Examples A-C are 
carried out to produce syndiotactic polystyrene using the catalysts of 
Examples 1-6, and the following Comparative Examples A1-A3, B1-B3 and 
C1-C3 are carried out to compare with Examples 1-6. 
Examples 1-6 
Representative catalysts of ABBM, SBBM and A-SBBM are prepared in the 
following manner. 
Example 1: snythesis of butane-bis(.eta..sup.5 
-diindenyltitanium-trichloride): [IndTiCl.sub.3 -(CH.sub.2).sub.4 
-IndTiCl.sub.3 ] 
After dissolving 10 mmole of 1,4-dibromobutane in 100 ml of tetrahydrofuran 
(THF), to the solution were added butyl lithium and indene to produce 
white powder. The white powder 20 mmole was dissolved in 50 ml of TMF at 
-78.degree. C., the solution was heated at room temperature, and then 
agitated for about 30 hours. To the solution was added 200 ml of 
diethylether and 100 ml of water to prepare a greasy type reaction 
mixture. To the mixture was added 50 ml of hexane, and a white powder 
ligand that two indenes were bridged was obtained in 90% of yield. To 9 
mmol of the ligand compound was added 50 ml of hexane, 18 mmol of butyl 
lithium was added at -78.degree. C., the solution was heated at room 
temperature, and then agitated for about 5 hours. A white powder dianion 
compound in which two indenyls were bonded to lithium atoms was obtained. 
After filtering the dianion compound, trimethylsilylchloride (TMSCl) was 
added in 100 ml of hexane solvent, agitated for 8 hours at room 
temperature, LiCl produced during the reaction was removed by filtration, 
and the solvent was removed under a reduced pressure. The resultant 
compound in which two indenyls are alkylene bridged and bonded to 
trimethylsilane groups was obtained in 7.2 mmole. The yield of the 
compound is 80%. To the resultant compound was added a solution of 
TiCl.sub.4 14.5 mmole in 30 ml of dichloromethane at room temperature. 
After 10 hours, the solvent was removed under a reduced pressure to obtain 
a dark wine color solid. The solid was washed in 20 ml of hexane three 
times, recrystallized with dichloromethane and hexane to obtain 
IndTiCl.sub.3 -(CH.sub.2)-IndTiCl.sub.3 catalyst ("catalyst 1"). The yield 
of the catalyst was 65% 
Example 2: snythesis of tetramethyldisilane-bis(.eta..sup.5 
-diindenyl-titaniumtrichloride): [IndTiCl.sub.3 
-(Si(CH.sub.3).sub.2).sub.2 -IndTiCl.sub.3 ] 
After dissolving 10 mmole of 1,2-dichlorotetramethyldisilane in 100 ml of 
tetrahydrofuran (THF), to the solution were added butyl lithium and indene 
to produce white powder. The white powder 20 mmole was dissolved in 50 ml 
of TMF at -78.degree. C., the solution was heated at room temperature, and 
then agitated for about 30 hours. To the solution as added 200 ml of 
diethylether and 100 ml of water to prepare a greasy type reaction 
mixture. To the mixture was added 50 ml of hexane, and a white powder 
ligand that two indenes were bridged was obtained in 85% of yield. To 8.5 
mmole of the ligand compound was added 50 ml of hexane, 17 mmole of butyl 
lithium was added at -78.degree. C., the solution was heated at room 
temperature, and then agitated for about 5 hours. A white powder dianion 
compound in which two indenyls are bonded to lithium atoms was prepared. 
After filtering the dianion compound, trimethylsilychloride (TMSCl) was 
added in 100ml of hexane solvent, agitated for 8 hours at room 
temperature, LiCl produced during the reaction was removed by filtration, 
and the solvent was removed under a reduced pressure. The resultant 
compound in which two indenyls are alkylene bridged and bonded to 
trimethylsilane groups was obtained in 0.4 mmole. The yield of the 
compound is 75%. To the resultant compound was added a solution of 
TiCl.sub.4 13 mmole in 30 ml of dichloromethane at room temperature. After 
10 hours, the solvent was removed under a reduced pressure to obtain a 
dark wine color solid. The solid was washed in 20 ml of hexane three 
times, recrystallized with dichloromethane and hexane to obtain 
IndTiCl.sub.3 -(Si(CH.sub.3).sub.2).sub.2 -IndTiCl.sub.3 catalyst 
("catalyst 2"). The yield of the catalyst was 50%. 
Example 3: synthesis of [bis(dimethylsilyl)]butane-[bis(.eta..sup.5 
-diindenyl-titaniumtrichloride)]: [IndTiCl.sub.3 -Si(CH.sub.3).sub.2 
-(CH.sub.2).sub.4 -Si(CH.sub.3).sub.2 -IndTiCl.sub.3 ] 
After dissolving 10 mmole of 1,4-bis(chlorodimethylsilyl)butane in 100 ml 
of tetrahydrofuran (THF), to the solution were added butyl lithium and 
indene to produce white powder. The white powder 20 mmole was dissolved in 
50 ml of TMF at -78.degree. C., the solution was heated at room 
temperature, and then agitated for about 20 hours. To the solution was 
added 200 ml of diethylether and 100 ml of water to prepare a greasy type 
reaction mixture. To the mixture was added 50 ml of hexane, and a white 
powder ligand that two indenes were bridged was obtained in 85% of yield. 
To 8.5 mmole of the ligand compound was added 50 ml of hexane, 17 mmole of 
butyl lithium was added at -78.degree. C., the solution was heated at room 
temperature, and then agitated for about 8 hours. A white powder dianion 
compound in which two indenyls are bonded to lithium atoms was prepared. 
After filtering the dianion compound, trimethylsilychloride (TMSCl) was 
added in 100 ml of hexane solvent, agitated for 8 hours at room 
temperature LiCl produced during the reaction was removed by filtration, 
and the solvent was removed under a reduced pressure. The resultant 
compound in which two indenyls are alkylene bridged and bonded to 
trimethylsilane groups was obtained in 6.4 mmole. The yield of the 
compound is 75%. To the resultant compound was added a solution of 
TiCl.sub.4 13 mmole in 30 ml of dichloromethane at room temperature. After 
10 hours, the solvent was removed under a reduced pressure to obtain a 
dark wine color solid. The solid was washed in 20 ml of hexane three 
times, recrystallized with dichloromethane and hexane to obtain 
IndTiCl.sub.3 -Si(CH.sub.3).sub.2 -(CH.sub.2).sub.4 
-Si(CH.sub.3).sub.2)-IndTiCl.sub.3 catalyst ("catalyst 3"). The yield of 
the catalyst was 40%. 
Although Examples 1-3 illustrate binuclear metallocene catalysts containing 
two indenyls, catalysts containing any two groups selected from a 
cyclopentadienyl; an alkyl alkoxy, silyl or halogen substituted 
cyclopentadienyl; an alkyl, alkoxy, silyl or halogen substituted indenyl; 
a fluorenyl; and an alkyl, alkoxy, silyl or halogen substituted fluorenyl 
can be obtained in the same manner above. 
Alkylene and/or silylene bridged hetero-bimetallic metallocene catalysts 
can be prepared by reacting TiCl.sub.4, ZrCl.sub.4 and HfCl.sub.4 
consecutively with the salt state compound of the bridged compound or a 
ligand having two trimethylsilanes. The following Examples 4-6 are to 
prepare hetero-bimetallic metallocene catalysts having Ti and Zr as 
binuclear metal. 
Example 4; synthesis of butane-bis(.eta..sup.5 
-cyclopentadienyltitanium-trichloride) (.eta..sup.5 
-cyclopentadienylzirconiumtrichloride): [CpTiCl.sub.3 -(CH.sub.2).sub.4 
-CpZrCl.sub.3 ]("catalyst 4") 
Example 4 was performed as in Example 1 with the exceptions that 
cyclopentadiene was employed instead of indene, and that TiCl.sub.4 and 
ZrCl.sub.4 were consecutively employed instead of TiCl.sub.4. 
Example 5: synthesis of tetramethyldisilane (.eta..sup.5 
-cyclopentadienyl-titaniumtrichloride) (.eta..sup.5 
-cyclopentadienylzirconiumtrichloride): [CpTiCl.sub.3 
-(Si(CH.sub.3).sub.2).sub.2 -CpZrCl.sub.3 ]("catalyst 5") 
Example 5 was performed as in Example 2 with the exceptions that 
cyclopentadiene was employed instead of indene, and that TiCl.sub.4 and 
ZrCl.sub.4 were consecutively employed instead of TiCl.sub.4. 
Example 6: synthesis of bis(dimethylsilyl)butane(.eta..sup.5 
-cyclopenta-dienyltitaniumtrichloride) (.eta..sup.5 
-cyclopentadienyl-zirconiumtrichloride): [CpTiCl.sub.3 -Si(CH.sub.3).sub.2 
-(CH.sub.2).sub.2 -Si(CH.sub.3).sub.2 -CpZrCl.sub.3 ]("catalyst 6") 
Example 6 was performed as in Example 3 with the exceptions that 
cyclopentadiene was employed instead of indene, and that TiCl.sub.4 and 
ZrCl.sub.4 were consecutively employed instead of TiCl.sub.4. 
Example A: homopolymerization of styrene 
Homopolymerization of styrene was carried out using the alkylene and/or 
silylene bridged binuclear metallocene catalysts prepared in Examples 1-6. 
Styrene was polymerized using a glass reactor equipped with a temperature 
controlled apparatus, a magnetic agitator and valves for supplying 
monomers and nitrogen. A purified toluene and MMAO as co-catalyst were put 
into a nitrogen-substituted reactor, mixed and stirred sufficiently. 
Styrene was added to the reactor. The alkylene and/or silylene bridged 
binuclear metallocene catalyst was added to the reactor and polymerization 
was carried out. The polymerization was terminated by adding ethanol. 
Syndiotactic polystyrene was obtained by adding HCl/CH.sub.3 OH solution 
to the resultant, washing with water and methanol, and vacuum-drying. In 
the polymerization of styrene, the ratio of [Al] to [Ti] was 1,000:1, the 
polymerization temperature was 40' C., and the content of styrene was 1.0 
mole/l. 
The following Table 1 sets forth catalyst activity, stereoregularity, 
melting point, molecular weight and molecular weight distribution in 
accordance with the catalysts of Examples 1-6. 
Example B: copolymerization of styrene 
Example B was performed as in Example A with the exception that 1.0 mole/l 
of styrene and 6% by weight of para-methylstyrene per the styrene were 
employed instead of 1.0 mole/l of styrene. 
The following Table 2 sets forth catalyst activity, melting point, 
molecular weight and molecular weight distribution in accordance with the 
catalysts of Examples 1-6. 
Example C: terpolymerization of styrene 
Example C was performed as in Example A with the exception that 1.0 mole/l 
of styrene, 6% by weight of para-methylstyrene per the styrene and 2% by 
weight of polybutadiene per the styrene were employed instead of 1.0 
mole/l of styrene. 
The following Table 3 sets forth catalyst activity, melting point, 
molecular weight and molecular weight distribtuion in accordance with the 
catalysts of Examples 1-6. 
Comparative Examples A1, B1 and C1 
Examples A1, B1 and C1 were performed as in Examples A, B and C, 
respectively, with the exception that cyclopentadienyl-titaniumtrichloride 
(CpTiCl.sub.3) was employed as catalyst. 
The physical properties for Comparative Examples A1, B1 and C1 are shown in 
Tables 1, 2 and 3, respectively. 
Comparative Examples A2, B2 and C2 
Examples A2, B2 and C2 were performed as in Examples A, B amd C, 
respectively, with the exception that 
pentamethylcyclopentadienyltitaniumtrichloride (Cp*TiCl.sub.3) was 
employed as catalyst. 
The physical properties for Comparative Examples A2, B2 and C2 are shown in 
Tables 1, 2 and 3, respectively. 
Comparative Examples A3, B3 and C3 
Examples A3, B3 and C3 were performed as in Examples A, B and C, 
respectively, with the exception that indenyltitaniumtrichloride 
(IndTiCl.sub.3) was employed as catalyst. 
The physical properties for Comparative Examples A3, B3 and C3 are shown in 
Tables 1, 2 and 3, respectively. 
TABLE 1 
__________________________________________________________________________ 
homopolymerization 
molecular 
molecular 
catalyst stereo- melting point weight weight 
catalyst activity regularity (.degree. C.) (.times. 10.sup.-3) distribut 
ion 
__________________________________________________________________________ 
Example A 
catalyst 1 
5,000 
97.5 271 280 3.5 
catalyst 2 3,800 96.0 270 250 3.5 
catalyst 3 3,500 96.0 
270 200 3.5 
catalyst 4 1,200 93.0 270 110 3.0 
catalyst 5 1,000 92.0 
270 100 3.2 
catalyst 6 1,000 91.0 269 100 3.5 
Comparative A1 CpTiCl.sub.3 
1,500 86.0 268 110 
2.6 
Example A2 IndTiCl.sub.3 3,500 93.0 270 210 
2.4 
A3 Cp*TiCl.sub.3 5,000 94.0 270 250 
2.3 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
copolymerization 
molecular 
molecular 
catalyst melting point weight weight 
catalyst activity (.degree. C.) (.times. 10.sup.-3) distribution 
__________________________________________________________________________ 
Example B 
catalyst 1 
4,000 
245 180 2.57 
catalyst 2 2,500 244 150 2.55 
catalyst 3 1,500 243 150 2.34 
catalyst 4 1,200 244 130 2.54 
catalyst 5 900 242 100 3.21 
catalyst 6 900 243 110 3.23 
Comparative B1 CpTiCl.sub.3 1,300 242 110 2.76 
Example B2 IndTiCl.sub.3 2,300 243 150 1.88 
B3 Cp*TiCl.sub.3 4,100 243 170 1.75 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
terpolymerization 
molecular 
molecular 
catalyst melting point weight weight 
catalyst activity (.degree. C.) (.times. 10.sup.-3) distribution 
__________________________________________________________________________ 
Example C 
catalyst 1 
4,200 
227 250 2.33 
catalyst 2 3,500 230 230 2.34 
catalyst 3 1,500 228 200 2.35 
catalyst 4 1,300 229 150 
2.33 
catalyst 5 1,000 227 110 2.33 
catalyst 6 1,000 228 100 
2.34 
Comparative C1 CpTiCl.sub.3 1,500 226 110 
1.95 
Example C2 IndTiCl.sub.3 3,100 227 200 1.92 
C3 Cp*TiCl.sub.3 -4,500 
227 220 1.91 
__________________________________________________________________________ 
The stereoregularity of catalysts in Table 1 was analyzed with .sup.1 H-NMR 
and .sup.13 C-NMR. 
The catalyst activity (kg PS/[Ti][St]hrs) in Tables 1, 2 and 3 was obtained 
by measuring the weight of the syndiotactic polystyrene prepared. 
The stereoregularity in Table 1 was obtained in percent (%) by measuring 
the weight of the polymer which was extracted with methylethylketone, 
corresponding to syndioactic index (S.I.). 
The melting point and crystallization temperature in Tables 1, 2 and 3 were 
obtained using the Du Pont 2000 System (Differential Scanning Calorimetry: 
DSC). The test sample was heated to 200.degree. C. and maintained for 
cooling for 5 minutes. The temperature rate was 10.degree. C./min. 
As shown in Tables 1-3, the catalyst activities of Examples 1-3 are much 
higher than those of Comparative Examples A1, B1 and C1, same or higher 
than those of Comparative Examples A2, B2 and C2, but same or lower than 
those of Comparative Examples A3, B3 and C3. However, the 
stereoregularities (S.I.) of Examples 1-3 are higher than those of 
Comparative Examples A1, A2 and A3. The melting points of the homopolymer, 
copolymer and terpolymer are about 270.degree. C., 244.degree. C. and 
227.degree. C., respectively. In case of using catalysts 1-3, molecular 
weight distributions are broader than those of the Comparative Examples, 
but molecular weights are higher as a whole. 
In regard to catalysts 4-6 of Examples 4-6, the catalyst activities are 
almost same as those of Comparative Examples A1, B1 and C1, and lower than 
those of Comparative Examples A2, B2, C2, A3, B3 and C3. The 
stereoregularities (S.I.) of Examples 4-6 are superior to Comparative 
Example A1, but similar to those of Comparative Examples A2 and A3. The 
melting points of the homopolymer, copolymer and terpolymer according to 
Examples 4-6 are about 270.degree. C., 244.degree. C. and 227.degree. C., 
respectively. In case of using catalysts 4-6, molecular weight 
distributions are broader than those of the Comparative Examples, but 
molecular weights are similar as a whole. 
Consequently, the alkylene and/or silylene bridged binuclear metallocene 
catalysts according to this invention are capable of preparing a 
syndioactic polystyrene having more stereoregularity and higher melting 
point and crystallization temperature than the conventional metallocene 
catalysts. 
Further modifications of the invention will be apparent to those skilled in 
the ant and all such modifications are deemed to be with the scope of the 
invention as defined in the following claims.