Abstract: A method for purifying a transition metal compound, which comprises conducting crystallization of a transition metal compound from a solution containing the transition metal compound while stirring.According to the present invention, it is possible to purify and produce efficiently a transition metal compound at high purity under industrially and economically advantageous conditions.

Abstract: A catalyst precursor having the formula:A.sub.q ML.sub.nwherein each A has the formula: ##STR1## M is a metal selected from the group consisting of Group 3 to 6 elements and Lanthanide series elements;each L is a monovalent, bivalent, or trivalent anion;X and Y are each heteroatoms;Cyclo is a cyclic moiety;each R.sup.1 is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements, and two or more adjacent R.sup.1 groups may be joined to form a cyclic moiety;each R.sup.2 is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements, and two or more adjacent R.sup.

Abstract: Disclosed are novel cyclopentadienyl transition metal compounds that are stable under a wide variety of conditions, particularly under conditions that include exposure to water and oxygen containing media. These novel compounds can be utilized in preparing novel catalyst systems useful in polymerizing olefins. The cyclopentadienyl compound can specifically be [(C5H4CH2CH2N[H]Me2)TiCl3]+B[C6F5]4-. Also disclosed are processes for preparing the novel cyclopentadienyl transition metal compounds.

Abstract: Titanium and zirconium complexes comprising one or more, cyclic, delocalized .pi.-bonded ligand groups wherein the metal of said complexes is in the +2 formal oxidation state are prepared in high yield and purity by reaction of the corresponding titanium or zirconium halides in the +3 or +4 oxidation state with a di(C.sub.1-20 alkyl) magnesium reagent. The complexes are used as catalyst components for olefin polymerization catalysts.

Abstract: Group 4 metal constrained geometry complexes comprising a fused ring indenyl derivative ligand, catalytic derivatives thereof, processes for preparing the same and their use as components of olefin polymerization catalysts are disclosed.

Abstract: Disclosed herein are processes for polymerizing ethylene, acyclic olefins, and/or selected cyclic olefins, and optionally selected olefinic esters or carboxylic acids, and other monomers. The polymerizations are catalyzed by selected transition metal compounds, and sometimes other co-catalysts. Since some of the polymerizations exhibit some characteristics of living polymerizations, block copolymers can be readily made. Many of the polymers produced are often novel, particularly in regard to their microstructure, which gives some of them unusual properties. Numerous novel catalysts are disclosed, as well as some novel processes for making them. The polymers made are useful as elastomers, molding resins, in adhesives, etc. Also described herein is the synthesis of linear .alpha.-olefins by the oligomerization of ethylene using as a catalyst system a combination a nickel compound having a selected .alpha.-diimine ligand and a selected Lewis or Bronsted acid, or by contacting selected .alpha.

Abstract: A catalyst composition prepared by reacting together (a) a source of a Group VIII metal; (b) a bidentate phosphine ligand having at least two phosphorus atoms joined by a bridging group of the formula --(N).sub.x --(P).sub.y --N-- where x is 0 or 1; and (c) a promoter is disclosed. The Group VIII metal is preferably palladium. The promoter can be a weakly or non-coordinating anion. Alternatively it can be a boron hydrocarbyl compound or an aluminoxane. Also disclosed are novel bidentate phosphine ligands and intermediates therefor as well as novel palladium complexes. The catalysts are used in the preparation of polyketones.

Abstract: A practical and scalable process for the synthesis of constrained geometry metallocene catalyst is described.

Abstract: Metal complexes having constrained geometry and a process for preparation thereof, addition polymerization catalysts formed therefrom, processes for preparation of such addition polymerization catalysts, methods of use, and novel polymers formed thereby, including ElPE resins and pseudo-random copolymers, are disclosed and claimed.

Abstract: A novel metallocene catalyst for the polymerization of olefin (co)polymers is of the general formula:R--SO.sub.2 --L--M--(X).sub.m T.sub.nwherein,M is a metal selected from Groups 3-10;T is a polymerization-stable anionic ancillary ligand;m+n is the valency of M minus 1;R is a C.sub.1 -C.sub.20 alkyl group, a C.sub.6 -C.sub.20 aryl ring or a C.sub.6 -C.sub.20 alkaryl or aralkyl group, optionally substituted with a halogen or an alkoxy group up to 10 carbon atoms;X is a halogen, alkoxy from C.sub.1 to C.sub.20, siloxy from C.sub.1 to C.sub.20, N(R).sub.2, a hydrocarbyl group containing up to about 12 carbon atoms, hydrogen or another univalent anionic ligand, or mixtures thereof;L is T as defined above with the proviso that one of the sites available for substitution is the attachment site of the sulfonyl group; andwherein L and T may be bridged.

Abstract: A chiral ligand system for transition or main group metal catalysts is disclosed. These ligands can be readily synthesized using inexpensive amino acids and diamines as starting materials. Several different transition or main group metals have been inserted into the ligands. The ligands have been shown to have a tetradhedral distortion that may contribute to enhanced chiral transfer from the catalyst to the substrate in chemical modifications of olefins and other reactive substrates. These catalysts have been demonstrated to be effective in catalyzing epoxidation of a variety of substrates.

Abstract: Catalyst component for the polymerization of alpha-olefins of general formula (I) ##STR1## wherein: M is a transition metal of groups 3, 4-10, lanthanide or actinide of the periodic table of the elements; A is a ring with delocalized .pi. electrons, L is a neutral Lewis base; m is an integer whose value can be: 0 or 1; E is selected from the group comprising: BR.sup.II, CR.sup.II.sub.2, SiR.sup.II.sub.2, GeR.sup.II.sub.2 ; Hal is selected from the group comprising iodine, bromine or chlorine; R.sup.III has the same meaning of R.sup.II ; Si is a silicon atom; D is selected from the group comprising: O, S, NR.sup.IV, PR.sup.IV, OR.sup.IV, SR.sup.IV, NR.sup.IV.sub.2, PR.sup.IV.sub.2 ; each X group equal to or different from each other is selected from the group comprising hydrogen, halide, alkyl, cycloalkyl, aryl, alkenyl, arylallyl, arylalkenyl or alkylaryl with 1 to 20 carbon atoms, n is a number whose value can be: 0, 1, 2 or 3, in order to full the remaining valences of metal M.

Abstract: Zirconocenes and hafnocenes with borylated cyclopentadienyl ligands and methods for the preparation thereof.

Abstract: Process for the free-radical polymerisation of olefinically unsaturated monomer(s) using a free-radical initiator, the polymerisation being performed in the presence of a compound for effecting molecular weight control, wherein the molecular weight control compound is a Co Il chelate of the following formula I ##STR1## wherein each group X, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 carbon atoms; n, independently in each ring, is 0 to 5 provided that in at least one ring, n is 1 to 5; Z, independently on each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms, and aryl of 6 to 12 carbon atoms; or two Z groups taken together provide on one or both boron atoms a group --O--(Q)--O-- where Q is a divalent aryl or alicyclic linking group or an alkylene linking group, or two Z groups taken together on one or both boron atoms provide a

Abstract: Described are certain monocyclopentadienyl Group IV B metal compounds, catalyst systems comprising such monocyclopentadienyl metal compounds and an activator, and a process using such catalyst systems for the production of polyolefins, particularly high molecular weight ethylene-.alpha.-olefin copolymers having a high level of .alpha.-olefin incorporation.

Abstract: A polymerizable composition comprises an alpha-olefin hydrocarbon monomer, an effective amount of an organometallic catalyst of a Group VIII metal, preferably Ni or Pd, and at least one of water and air. Novel catalysts for polymerizing alpha-olefin hydrocarbon monomers provide improved processes and products. Methods of the invention include polymerizing the composition in open air and in the presence of water to provide novel polymers.

Abstract: Single component metallocene catalysts for .alpha.-olefin polymerization are disclosed. Prior art cation metallocene catalysts have required a separate anion co-catalyst like methyl aluminoxane (MAO). However, because the inventive zwitterion ansa metallocene (ZAM) catalysts have a "built-in" anion co-catalyst functionality, the need for a separate anion co-catalyst is eliminated.

Abstract: Chiral compounds of the formula I ##STR1## where the variables are as described in the specification.

Abstract: The hydrolyzable and polymerizable silanes have the formula I, ##STR1## wherein X is hydrogen, a halogen, a hydroxy, an alkoxy group, an acyloxy oup, an alkylcarbonyl group, an alkoxycarbonyl group or --NR.sup.2.sub.2 group; wherein R.sup.

Abstract: A novel metallocene catalyst for the polymerization of olefin (co)polymers is of the general formula:Benzothiazole--E--M--X.sub.m L.sub.nwhere,M is a transition metal of Groups 3-10 of the Periodic Table;E is sulfur or oxygen; E being bond to the transition metal and to the carbon atom between sulfur and nitrogen of the benzothiazole moiety;L is a polymerization-stable anionic ancillary ligand;X is a halogen, alkoxy from C.sub.1 to C.sub.20, siloxy from C.sub.1 to C.sub.20, N(R.sub.1).sub.2, a hydrocarbyl group containing up to about 12 carbon atoms or hydrogen or mixtures thereof; preferably X is halogen, methoxy, ethoxy or siloxy (R.sub.1).sub.3 SiO--, where R.sub.1 is alkyl from C.sub.1 to C.sub.20 ; andm+n equals the valency of the M minus 1.

Abstract: The conversion of the achiral meso form of an ansa-metallocene complex into the chiral rac form is carried out photochemically in the presence of a chiral auxiliary reagent.

Abstract: The present invention relates to a process for preparing racemic ansa-metallocene complexes I ##STR1## tin compounds II ##STR2## and a process for preparing tin compounds II. R.sup.1 to R.sup.9, M, and X are defined herein.

Abstract: Disclosed is a novel transition metal compound represented by the following formula: ##STR1## wherein M is a transition metal, X is halogen or the like, R.sup.1 is a hydrocarbon group or the like, R.sup.2 is an aryl group substituted with a halogenated hydrocarbon group, and Y is a divalent silicon-containing group or the like.Also disclosed are an olefin polymerization catalyst component comprising the transition metal compound, an olefin polymerization catalyst comprising the olefin polymerization catalyst component, and a process for olefin polymerization using the olefin polymerization catalyst.An olefin polymerization catalyst component having high polymerization activity can be formed from the transition metal compound. By the use of the olefin polymerization catalyst or the process for olefin polymerization, polyolefins having a high melting point and a high molecular weight can be prepared with high polymerization activity.

Abstract: A cationic metallocene complex with trisperfluorobiphenyl borate for use as a polymerization catalyst.

Abstract: An olefin polymerization catalyst component is represented by the general formula (1); ##STR1## wherein M is titanium, zirconium or hafnium; each of A and A' is the same or different and is a hydrocarbon or halogenated hydrocarbon having 1 to 50 carbon atoms, or a hydrocarbon or halogenated hydrocarbon group having 1 to 50 carbon atoms and a substituent containing an oxygen atom; E is a residual group of an element of the 13th to 15th Groups capable of forming three bonds; each of R and R' is the same or different and is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms; R" represents a hydrocarbon or halogenated hydrocarbon group containing at least one hetero atom and having 1 to 20 carbon atoms. This component is used in a catalyst to produce an olefin polymer.

Abstract: In a process for converting the achiral meso form or the racemate of an ansa-metallocene complex or a mixture thereof into one of its enantiomers, the conversion is carried out photochemically in the presence of an enantiomerically pure auxiliary reagent.

Abstract: Metallocenes having benzo-fused indenyl derivatives as ligands, processes for their preparation and their use as catalystsA very effective catalyst system for olefin polymerization comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I ##STR1## in which, preferably, M.sup.1 is Zr or Hf, R.sup.1 and R.sup.2 are halogen or alkyl, R.sup.3 is alkyl, R.sup.4 to R.sup.10 are alkyl or hydrogen and R.sup.11 is a (substituted) alkylene or heteroatom bridge.

Abstract: In-situ process for preparing a bridged metallocene, which comprises reacting a substituted cyclopentadiene A, if desired an unsubstituted or substituted cyclopentadienyl compound B, at least one base, at least one bridging reagent and at least one metal component with one another.

Abstract: There is provided an organometallic compound comprising a metal M of Group 3 to 6 of the Periodic Table or the Lanthanide series and at least one (hetero)cyclohexadienyl ligand of the general formula (I)C.sub.5 AR.sub.nwherein A is an element chosen from Group 13 to 16 of the Periodic Table, R which can be connected to C or to A and which may form a bridge is independently hydrogen or an organic substituent which may contain one or more hetero-atoms and n is 3 plus the number of valencies of A. There is further provided the use of this compound as a catalyst, with a co-catalyst, in a process for the (co)oligomerisation or (co)polymerisation of olefinically unsaturated hydrocarbons.

Abstract: There is disclosed a catalyst composition prepared by reacting together:(a) a source of a Group VIII metal,(b) a compound of the formula (I)R.sup.1 R.sup.2 PR.sup.4 CO.sub.2 R.sup.3 (I)where R.sup.1 and R.sup.2 are independently an unsubstituted or substituted alkyl, cycloalkyl or aryl group, R.sup.3 is hydrogen, an unsubstituted or substituted alkyl, cycloalkyl or aryl group and R.sup.4 is a divalent organic group and(c) a source of an anion which is either non-coordinating or weakly-coordinating to the Group VIII metal.The catalyst compositions are used in the preparation of polyketones from carbon monoxide and one or more olefins. Novel compounds of the formula ?(.eta..sup.3 -allyl)Pd(R.sub.1 R.sup.2 PR.sup.4 CO.sub.2 R.sup.3)!A where A is a weakly or non-coordinating anion are useful as such catalysts.

Abstract: The present invention relates to a transition metal compound of the formula IL.sub.n (X.sub.m A.sub.t R.sup.1.sub.q).sub.s MY.sub.r (I),whereM is a metal atom of group IIIb, IVb, Vb or VIb of the Periodic Table of the Elements,L are identical or different and are each a .pi.-ligand or an electron donor, n is 1, 2, 3 or 4,Y are identical or different and are each a hydrogen atom, a halogen atom or an 1-dentate C.sub.1 -C.sub.40 -group, where l is 1, 2, 3 or 4, r is 0, 1, 2, 3, 4 or 5,and at least one of the radicals L bears at least one group X.sub.m A.sub.t R.sup.1.sub.q, whereX are identical or different and are each a hetero atom or a C.sub.1 -C.sub.40 -group, m is 0 or 1,A is an atom of group IIIa, Va or VIa of the Periodic Table of the Elements, t is 1,R.sup.1 are identical or different and are each a C.sub.1 -C.sub.40 -group, q is 1, 2, 3, 4 or 5 and s is an integer from 1 to 20.The transition metal compound of the invention is suitable as a catalyst component for olefin polymerization.

Abstract: The present invention makes available novel compounds useful for inhibiting kinases, phosphatases and SH2 domains, e.g., an interaction between a protein containing an SH2 domain and a phophotyrosine-containing polypeptide. In one embodiment, the present invention provides boronylphenyl analogs of phosphotyrosines which, in such forms as peptidomimetics, can be used to modulate signal transduction pathways in cells.

Abstract: A compound for effecting molecular weight control in polymerisation is a CoII chelate of formula, wherein each group R is an organic cyclic group which, independently, is a monovalent group which comprises a cyclic structure or taken together as two adjacent groups provides a divalent group, and wherein further at least one of the groups R includes at least one heteroatom selected from 0, N, S, P, halogen and Si, which heteroatom provides a substituent group or part of a substituent group on the cyclic structure, or a heteroatom of a heterocyclic ring of the cyclic structure; and wherein each group Q is independently selected from F, Cl, Br, OH, C.sub.1-12 alkoxy and C.sub.1-12 alkyl; or being a CoIII analogue of the cobalt II chelate of formula in which the Co atom is additionally covalently bonded to H, a halide or other anion, or a homolytically dissociable organic group. Free-radical polymerication of at least one ethylenically unsaturated monomer is carried out in the presence of such a compound.

Abstract: A catalyst composition prepared by reacting together:(a) a source of a Group VIII metal,(b) a bidentate phosphine ligand having at least two phosphorous atoms joined by a bridging group of the formula --NR.sup.2 (CX)NR.sup.2 where X.dbd.O, S or Se, each R.sup.2 is the same or different and is a hydrogen or hydrocarbyl group, and(c) a promoteris disclosed. The catalyst composition is used for preparing polyketones.

Abstract: The present invention relates to a metallocene compound of the formula I which is suitable for olefin polymerization ##STR1## where M is a metal of group IVb, Vb or VIb of the Periodic Table.X are each a hydrogen atom, a halogen atom or a C.sub.1 -C.sub.40 -radical OR.sup.4 or NR.sup.4.sub.2, where R.sup.4 are a C.sub.1 -C.sub.20 hydrocarbon radicalm and p are 1, 2 or 3,n is 1 or 2,L each a .pi. ligand which coordinates to the central atom M,M.sup.2 are each a silicon atom, a germanium atom or a tin atom,R.sup.1 are a C.sub.1 -C.sub.20 -radical,R.sup.2 are a C.sub.1 -C.sub.20 -radical or a .pi. ligand which coordinates to the central atom M,A are each a bidentate C.sub.1 -C.sub.40 -hydrocarbon group,Z are each a boron atom, a silicon atom, a germanium atom or a tin atom,R.sup.3 are each a hydrogen atom or a C.sub.1 -C.sub.20 -radical,o is zero, 1 or 2,Hal are each a halogen atom, andwhere n is 1 if R.sup.2 is a .pi. ligand which coordinates to the central atom M and n is 2 if R.sup.2 is a C.sub.1 -C.sub.

Abstract: A catalyst composition suitable for use in a process for the preparation of polyketones comprising a group VIII metal complex of a phosphonite of formula (I)R.sup.1 R.sup.2 E(OPR.sub.2.sup.3).sub.2.sup.-1 (I)where R.sup.1 and R.sup.2 are independently a halide or a hydrocarbyl.R.sup.3 is an optionally substituted hydrocarbylE is boron, aluminium or gallium.Preferred compositions are ?F.sub.2 B(OPPh.sub.2).sub.2 PdCl!.sub.2 and ?F.sub.2 B(OPPh.sub.2).sub.2 Pd(NCPh).sub.2 !.sup.+ ?BF.sub.4 !.sup.-.

Abstract: A catalyst system comprising an aluminoxane and a transition-metal component (metallocene) is used, the transition-metal component comprising at least one zirconocene of the formula I ##STR1## and at least one zirconocene of the formula Ia or alternatively at least 2 zirconocenes of the formula I.

Abstract: The invention relates to new transition metal compounds useful as olefin polymerization catalysts. They are characterized by the formula (V)(E)(W)M(L), which in which M is a transition metal, V, E, and W, is e.g.

Abstract: A process for preparing bridged mono- and bis(cyclopentadienyl) metal dihydrocarbyloxy coordination complexes (I) by contacting in the presence of an aprotic organic diluent a metal compound of the formula M(OR).sub.4 with a dianionic salt compound. A process for preparing bridged mono- and bis(cyclopentadienyl) dihydrocarbyl metal coordination complexes (II) by contacting a complex (I) with a hydrocarbylation agent. A process for preparing bridged mono- and bis(cyclopentadienyl) metal dihalide coordination complexes (III) by contacting a complex (I) with a halogenation agent.

Abstract: Polyolefins with a molecular weight distribution M.sub.w /M.sub.n .gtoreq.3.0, which may be monomodal, bimodal or multimodal, can be obtained by polymerization or copolymerization of olefins with a catalyst system consisting of an aluminoxane and a transition metal component (metallocene), in which the transition metal component consists of at least one zirconocene of the formula I and at least one zirconocene of the formula Ia ##STR1## or alternatively of at least 2 zirconocenes of the formula I.

Abstract: A very efficient catalyst system for the polymerization of 1-olefins consists of an aluminoxane and a metallocene which is a compound of the formula I ##STR1## in which R.sup.1 and R.sup.2 denote hydrogen atoms, halogen atoms or hydrocarbon radicals and R.sup.3 and R.sup.4 are mononuclear or polynuclear hydrocarbon radicals which can form a sandwich structure with the central atom and which are linked to one another by a --R.sup.6.sub.m --R.sup.5 --R.sup.7.sub.n -- bridge containing a hetero atom and consisting of one or several members.The catalyst system produces polymers having a high molecular weight and excellent grain morphology.

Abstract: A very efficient catalyst system for the polymerization of 1-olefins consists of an aluminoxane and a metallocene which is a compound of the formula I ##STR1## in which R.sup.1 and R.sup.2 denote hydrogen atoms, halogen atoms or hydrocarbon radicals and R.sup.3 and R.sup.4 are mononuclear or polynuclear hydrocarbon radicals which can form a sandwich structure with the central atom and which are linked to one another by a --R.sup.6.sub.m --R.sup.5 --R.sup.7.sub.n -- bridge containing a hetero atom and consisting of one or several members.The catalyst system produces polymers having a high molecular weight.

Abstract: Metal organic compounds containing both cobalt and nickel bound to boron are effective adhesion promoters for bonding rubber to brass-coated metal used as a reinforcement.

Abstract: Novel onium borates of an element of Groups 15 to 17 of the Periodic Table, or borates of an organometallic complex of an element of Groups 4 to 10 of the Periodic Table, well suited for the photochemical/electron beam cationic initiation of polymerization/crosslinking, the anionic borate moiety of which having the formula:[BX.sub.a R.sub.b ].sup.-in which a and b are integers ranging from 0 to 4 and a+b=4; the symbols X are each a halogen atom when a ranges up to 3 and an OH functional group when a ranges up to 2; and the symbols R, which may be identical or different, are each a phenyl radical substituted by at least one element or electron-withdrawing substituent or by at least two halogen atoms, or an aryl radical containing at least two aromatic ring members, or such aryl radical bearing at least one electron-withdrawing substituent.

Abstract: Boron-zirconium 1,1,-dimetallic organic compounds useful in organic synthesis such as the preparation of alpha-borobromanes. The boron-zirconium compounds include boron and zirconiun, and in particular the synthesis, structure and reactivity of E-chlorobis(cyclopentadienyl)- [1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)-3,3-dimethylbutenyl]zirc onium (IV). The boron-zirconium 1,1-dimetallic compound is used as a polymerization catalyst to polymerize alpha-olefins such as styrene.

Abstract: Bridged monocyclopentadienyl derivatives of a Group 4 metal are prepared by contacting a corresponding bis(cyclopentadienyl) metal complex with an alkali metal derivative or alkaline earth metal derivative of a hydrocarbyl ligand R, which is optionally substituted with one or more amino, phosphino, ether, thioether, or silyl groups. The bis(cyclopentadienyl) Group 4 metal complexes can be prepared by contacting a compound corresponding to one of the formulas (Cp).sub.3 MQ.sub.n X.sub.t, (Cp).sub.2 MQ.sub.n X.sub.t+1, or CpMQ.sub.n X.sub.t+2 and a dianionic salt compound corresponding to the formula: (L.sup.+x).sub.y (Cp*-Z-Y).sup.-2 or ((LX').sup.+x).sub.y (Cp*-Z-Y).sup.-2. An addition polymerization catalyst comprising a bis(cyclopentadienyl) Group 4 metal complex and an activating cocatalyst, and an addition polymerization process using such a catalyst.

Abstract: Compounds of formula (I) are disclosed: ##STR1## wherein L.sup.1 is a main group atom, L.sup.2 is a neutral ligand, M is a transition element or a metal element of Group 13, 14, 15, or 16 of the Periodic Table, x is the number of coordination sites of M, R.sup.1 is a polymerizable group, R.sup.2, R.sup.3, and R.sup.4 are ligands, and R.sup.5 is an anionic ligand. The compounds or monomers of formula (I) are capable of conversion to polymers by combination with one or more other known monomers, such as methyl methacrylate. Such polymers can then be added as a binder in a paint formulation to make marine antifouling coating compositions. Also described is a method to prevent fouling on surfaces wherein a composition containing a metal complex compound of formula (II): ##STR2## wherein M, x, L.sup.2, n, and R.sup.4 have the same meaning as in formula (I), is applied to the surface susceptible to fouling.

Abstract: A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

Abstract: Isospecific and/or syndiospecific catalysts and processes for the propagation of an isotactic and/or syndiotactic polymer chain derived from an ethylenically unsaturated monomer which contains 3 or more carbon atoms or is a substituted vinyl compound. The catalysts comprise a stereorigid, stereodirected and stereolocked metallocene and/or metallocene cation catalysts, characterized by having .beta. stereodirecting substituents and .alpha. stereolocking substituents such that the catalysts have overall either C.sub.s or C.sub.2 (or pseudo-C.sub.s or C.sub.2) symmetry and such that the substituents define the orientation of the growing polymer chain end and resulting in tactioselectivity of successive monomer additions. Methods are also described for the preparation and use of these unique catalysts.

Abstract: Novel catalytic derivatives of titanium or zirconium complexes containing one and only one cyclic delocalized, anionic, .PI.-bonded group wherein the metal is in the +2 formal oxidation state and having a bridged ligand structure and an activating cocatalyst are useful as catalysts for polymerizing olefins, diolefins and/or acetylenically unsaturated monomers.