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that are linked by a bridging group such that both cyclopentadienyl groups are bound to the same metal. The link prevents rotation of the cyclopentadienyl ligand and often modifies the structure and reactivity of the metal center. Some ansa-metallocenes are active in
135:-metallocenes is in polymerisation reactions. Specifically, the ansa bridge allows greater control of the stereochemistry at the metal centre. For example, three distinct
281:
Bajgur, Chandrasekhar S.; Tikkanen, Wayne; Petersen, Jeffrey L. (1985). "Synthesis, structural characterization, and electrochemistry of metallocenophane complexes, MCl
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70:-metallocene (ansa being Greek for "handle") was coined by LĂĽttringhaus and Kullick to describe alkylidene-bridged
63:
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where n = 1, 2, and 3. More easily installed are linker groups consisting of heteroatoms, e.g. (CH
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144:
321:
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253:
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203:-metallocene polymerization catalysts: Effects of the bridges on the catalytic activities".
55:
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81:-metallocenes are described in terms of the angle defined by the two Cp rings. In
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Three views of ansa-dimethylsilylhafnocene dichloride (from X-ray coordinates).
19:
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148:
71:
300:
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160:
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58:
317:
Landmarks in Organo-Transition Metal
Chemistry: A Personal View
43:
refers to additional ligands that may reside on the metal M.
139:-zirconocene dichloride catalysts used in the synthesis of
54:
is a type of organometallic compound containing two
147:(MAO) can be used to direct whether the product is
112:The prototypical linker groups are of the type (CH
66:, although none are used commercially. The term
27:-metallocene. X is the linker group, often (CH
8:
18:
230:LĂĽttringhaus, A.; Kullick, W. (1958). "
191:
153:
74:, which were developed in the 1950s.
85:, this angle is 58.5° whereas in the
7:
149:syndiotactic, isotactic, or atactic
14:
177:
168:
159:
205:Coordination Chemistry Reviews
131:One potential application of
1:
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217:10.1016/j.ccr.2005.05.012
258:10.1002/ange.19580701407
64:Ziegler-Natta catalysis
23:Structure of a generic
16:Organometallic compound
44:
83:titanocene dichloride
22:
109:the angle is 51.2°.
314:Werner, H. (2008).
301:10.1021/ic00210a015
288:Inorganic Chemistry
250:1958AngCh..70R.438L
143:in the presence of
45:
39:Si (R = alkyl). L
331:978-0-387-09847-0
237:Angewandte Chemie
199:Wang, B (2006). "
145:methylaluminoxane
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322:Springer Science
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211:(1–2): 242–258.
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56:cyclopentadienyl
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324:. p. 161.
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285:, M = Ti, Zr".
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89:-titanocene Me
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234:-Ferrocene".
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351:Metallocenes
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295:(16): 2539.
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52:-metallocene
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244:(14): 438.
187:References
72:ferrocenes
345:Category
246:Bibcode
59:ligands
328:
264:
77:Often
326:ISBN
262:ISBN
232:Ansa
201:Ansa
137:ansa
133:ansa
128:Si.
105:TiCl
93:Si(C
87:ansa
79:ansa
68:ansa
50:ansa
35:or R
25:ansa
297:doi
254:doi
213:doi
209:250
47:An
347::
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293:24
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242:70
240:.
207:.
151:.
334:.
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299::
283:2
270:.
256::
248::
219:.
215::
126:2
124:)
122:3
118:n
116:)
114:2
107:2
103:2
101:)
99:4
97:H
95:5
91:2
41:n
37:2
33:n
31:)
29:2
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