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Unusual Hafnium–Pyridylamido/ER n Heterobimetallic Adducts (ER n =ZnR 2 or AlR 3 )
Author(s) -
Rocchigiani Luca,
Busico Vincenzo,
Pastore Antonello,
Talarico Giovanni,
Macchioni Alceo
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201308370
Subject(s) - adduct , chemistry , alkyl , olefin polymerization , nuclear magnetic resonance spectroscopy , polymerization , 1 hexene , crystallography , stereochemistry , medicinal chemistry , spectroscopy , catalysis , olefin fiber , ethylene , organic chemistry , polymer , physics , quantum mechanics
NMR spectroscopy and DFT studies indicate that the Symyx/Dow Hf(IV)–pyridylamido catalytic system for olefin polymerization, [{N − ,N,C Nph − }HfMe][B(C 6 F 5 ) 4 ] ( 1 , Nph=naphthyl), interacts with ER n (E=Al or Zn, R=alkyl group) to afford unusual heterobimetallic adducts [{N − ,N}HfMe(μ‐C Nph )(μ‐R)ER n −1 ][B(C 6 F 5 ) 4 ] in which the cyclometalated Nph acts as a bridge between Hf and E. 1 H VT (variable‐temperature) EXSY NMR spectroscopy provides direct evidence of reversible alkyl exchanges in heterobimetallic adducts, with ZnR 2 showing a higher tendency to participate in this exchange than AlR 3 . 1‐Hexene/ER n competitive reactions with 1 at 240 K reveal that the formation of adducts is strongly favored over 1‐hexene polymerization. Nevertheless, a slight increase in the temperature (to >265 K) initiates 1‐hexene polymerization.