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==Catalyst development==
==Catalyst development==
The catalyst is named after German chemist [[Walter Kaminsky]], who first described it in 1980 along with Hansjörg Sinn and others.<ref>{{Cite journal |last=Kaminsky |first=Walter |date=2004-08-15 |title=The discovery of metallocene catalysts and their present state of the art |url=https://onlinelibrary.wiley.com/doi/10.1002/pola.20292 |journal=Journal of Polymer Science Part A: Polymer Chemistry |language=en |volume=42 |issue=16 |pages=3911–3921 |doi=10.1002/pola.20292 |issn=0887-624X|url-access=subscription }}</ref><ref>{{Cite journal |last=Sinn |first=Hansjörg |last2=Kaminsky |first2=Walter |last3=Vollmer |first3=Hans‐Jürgen |last4=Woldt |first4=Rüdiger |date=1980 |title=“Living Polymers” on Polymerization with Extremely Productive Ziegler Catalysts |url=https://onlinelibrary.wiley.com/doi/10.1002/anie.198003901 |journal=Angewandte Chemie International Edition in English |language=en |volume=19 |issue=5 |pages=390–392 |doi=10.1002/anie.198003901 |issn=0570-0833|url-access=subscription }}</ref> Prior to Kaminsky's work, titanium chlorides supported on various materials were widely used (and still are) as heterogeneous catalysts for alkene polymerization. These halides are typically activated by treatment with [[trimethylaluminium]]. Kaminsky discovered that titanocene and related complexes emulated some aspects of these [[Ziegler–Natta catalyst]]s but with low activity. He subsequently found that high activity could be achieved upon activation of these metallocenes with methylaluminoxane (MAO). The MAO serves two roles: (i) alkylation of the metallocene halide and (ii) abstraction of an anionic ligand (chloride or methyl) to give an electrophilic catalyst with a labile coordination site.<ref name=Kaminsky/><ref name=chen>{{cite journal | title = Cocatalysts for Metal-Catalyzed Olefin Polymerization: Activators, Activation Processes, and Structure-Activity Relationships |author1=Chen, E. Y.-X. |author2=Marks, T. J. | journal = [[Chem. Rev.]] | year = 2000 | volume = 100 | issue = 4 | pages = 1391–1434 | doi = 10.1021/cr980462j | pmid=11749269|s2cid=26845820 }}</ref>
The catalyst is named after German chemist [[Walter Kaminsky]], who first described it in 1980 along with Hansjörg Sinn and others.<ref>{{Cite journal |last=Kaminsky |first=Walter |date=2004-08-15 |title=The discovery of metallocene catalysts and their present state of the art |url=https://onlinelibrary.wiley.com/doi/10.1002/pola.20292 |journal=Journal of Polymer Science Part A: Polymer Chemistry |language=en |volume=42 |issue=16 |pages=3911–3921 |doi=10.1002/pola.20292 |bibcode=2004JPoSA..42.3911K |issn=0887-624X|url-access=subscription }}</ref><ref>{{Cite journal |last1=Sinn |first1=Hansjörg |last2=Kaminsky |first2=Walter |last3=Vollmer |first3=Hans-Jürgen |last4=Woldt |first4=Rüdiger |date=1980 |title="Living Polymers" on Polymerization with Extremely Productive Ziegler Catalysts |url=https://onlinelibrary.wiley.com/doi/10.1002/anie.198003901 |journal=Angewandte Chemie International Edition in English |language=en |volume=19 |issue=5 |pages=390–392 |doi=10.1002/anie.198003901 |issn=0570-0833|url-access=subscription }}</ref> Prior to Kaminsky's work, titanium chlorides supported on various materials were widely used (and still are) as heterogeneous catalysts for alkene polymerization. These halides are typically activated by treatment with [[trimethylaluminium]]. Kaminsky discovered that titanocene and related complexes emulated some aspects of these [[Ziegler–Natta catalyst]]s but with low activity. He subsequently found that high activity could be achieved upon activation of these metallocenes with methylaluminoxane (MAO). The MAO serves two roles: (i) alkylation of the metallocene halide and (ii) abstraction of an anionic ligand (chloride or methyl) to give an electrophilic catalyst with a labile coordination site.<ref name=Kaminsky/><ref name=chen>{{cite journal | title = Cocatalysts for Metal-Catalyzed Olefin Polymerization: Activators, Activation Processes, and Structure-Activity Relationships |author1=Chen, E. Y.-X. |author2=Marks, T. J. | journal = [[Chem. Rev.]] | year = 2000 | volume = 100 | issue = 4 | pages = 1391–1434 | doi = 10.1021/cr980462j | pmid=11749269|s2cid=26845820 }}</ref>
==Ligand design==
==Ligand design==
Kaminsky's discovery of well-defined, high activity homogeneous catalysts led to many innovations in the design of novel cyclopentadienyl ligands. These innovations include [[ansa-metallocene]]s, C<sub>s</sub>-symmetric fluorenyl-Cp ligands,<ref>{{cite journal|author1=Ewen, J. A.|author2=Jones, R. L.|author3=Razavi, A.|author4=Ferrara, J. D.|title=Syndiospecific propylene polymerizations with Group IVB metallocenes|journal=Journal of the American Chemical Society|year=1988|volume=110|issue=18|pages=6255–6256|doi=10.1021/ja00226a056|pmid=22148816}}</ref> [[Constrained geometry complex|constrained geometry catalysts]],<ref>{{cite journal | author = Shapiro P. J., Bunel E., Scbaefer W. P., Bercaw J. E. | year = 1990 | doi = 10.1021/om00117a055 | title = Scandium Complex [{(η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>)Me<sub>2</sub>Si(η<sup>1</sup>-NCMe<sub>3</sub>)}(PMe<sub>3</sub>)ScH]<sub>2</sub>: A Unique Example of a Single-Component α-Olefin Polymerization Catalyst | journal = Organometallics | volume = 9 | pages = 867–869 }}</ref> Some Kaminsky-inspired catalysts use of [[Chirality (chemistry)|chiral]] metallocenes that have bridged [[cyclopentadienyl]] rings. These innovations made possible highly stereoselective (or stereoregular) polymerization of [[α-olefin]]s, some of which have been commercialized.<ref name=Klosin/>
Kaminsky's discovery of well-defined, high activity homogeneous catalysts led to many innovations in the design of novel cyclopentadienyl ligands. These innovations include [[ansa-metallocene]]s, C<sub>s</sub>-symmetric fluorenyl-Cp ligands,<ref>{{cite journal|author1=Ewen, J. A.|author2=Jones, R. L.|author3=Razavi, A.|author4=Ferrara, J. D.|title=Syndiospecific propylene polymerizations with Group IVB metallocenes|journal=Journal of the American Chemical Society|year=1988|volume=110|issue=18|pages=6255–6256|doi=10.1021/ja00226a056|pmid=22148816|bibcode=1988JAChS.110.6255E }}</ref> [[Constrained geometry complex|constrained geometry catalysts]],<ref>{{cite journal | author = Shapiro P. J., Bunel E., Scbaefer W. P., Bercaw J. E. | year = 1990 | doi = 10.1021/om00117a055 | title = Scandium Complex [{(η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>)Me<sub>2</sub>Si(η<sup>1</sup>-NCMe<sub>3</sub>)}(PMe<sub>3</sub>)ScH]<sub>2</sub>: A Unique Example of a Single-Component α-Olefin Polymerization Catalyst | journal = Organometallics | volume = 9 | pages = 867–869 }}</ref> Some Kaminsky-inspired catalysts use of [[Chirality (chemistry)|chiral]] metallocenes that have bridged [[cyclopentadienyl]] rings. These innovations made possible highly stereoselective (or stereoregular) polymerization of [[α-olefin]]s, some of which have been commercialized.<ref name=Klosin/>
[[File:metallocenes3.png|thumb|420px|center|Using metallocene '''1''' for polymerization of propene gives [[atactic]] [[polypropylene]], while ''C''<sub>2</sub> [[Molecular symmetry|symmetric]] metallocene '''2''' and ''C''<sub>s</sub> symmetric metallocene '''3''' catalytic systems produce [[isotactic]] polymer and [[syndiotactic macromolecule|syndiotactic]] polymer, respectively.]]
[[File:metallocenes3.png|thumb|420px|center|Using metallocene '''1''' for polymerization of propene gives [[atactic]] [[polypropylene]], while ''C''<sub>2</sub> [[Molecular symmetry|symmetric]] metallocene '''2''' and ''C''<sub>s</sub> symmetric metallocene '''3''' catalytic systems produce [[isotactic]] polymer and [[syndiotactic macromolecule|syndiotactic]] polymer, respectively.]]
The catalyst is named after German chemist Walter Kaminsky, who first described it in 1980 along with Hansjörg Sinn and others.[3][4] Prior to Kaminsky's work, titanium chlorides supported on various materials were widely used (and still are) as heterogeneous catalysts for alkene polymerization. These halides are typically activated by treatment with trimethylaluminium. Kaminsky discovered that titanocene and related complexes emulated some aspects of these Ziegler–Natta catalysts but with low activity. He subsequently found that high activity could be achieved upon activation of these metallocenes with methylaluminoxane (MAO). The MAO serves two roles: (i) alkylation of the metallocene halide and (ii) abstraction of an anionic ligand (chloride or methyl) to give an electrophilic catalyst with a labile coordination site.[1][5]
Ligand design
Kaminsky's discovery of well-defined, high activity homogeneous catalysts led to many innovations in the design of novel cyclopentadienyl ligands. These innovations include ansa-metallocenes, Cs-symmetric fluorenyl-Cp ligands,[6]constrained geometry catalysts,[7] Some Kaminsky-inspired catalysts use of chiral metallocenes that have bridged cyclopentadienyl rings. These innovations made possible highly stereoselective (or stereoregular) polymerization of α-olefins, some of which have been commercialized.[2]
