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A Valence Bond Analysis of Olefin Polymerization Catalysts. Timothy K. Firman and Tom Ziegler. p -Conjugated Ligands in d 0 Systems. X groups are isolobally analogous. Several good catalysts of this type are known. Resonance Structures. A localized bonding picture of these ligands - PowerPoint PPT Presentation
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A Valence Bond Analysis of Olefin Polymerization Catalysts
Timothy K. Firman and Tom Ziegler
-Conjugated Ligands in d0 Systems
X X
X X
X= CR2, SiR2, NR, PR, O, S
X groups are isolobally analogous
Several good catalysts of this type are known
Resonance StructuresA localized bonding picture of these ligandsrequires multiple resonance structures, e.g.:
HC
HN NH
M+
- HC
HN NH
M
HC
HN NH
M
Main group elements require an octet of electronsBond order to metal is variable, which may facilitate bond breaking during olefin insertion
Model Compounds
X= CH2, SiH2, NH, PH, O, S
TiX
HC X X CHX
PTiX
X X
X
P
+ +