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The Reaction of (Butadiene)zirconocene with Imines
Author(s) -
Höltke Carsten,
Erker Gerhard,
Kehr Gerald,
Fröhlich Roland,
Kataeva Olga
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200211)2002:11<2789::aid-ejic2789>3.0.co;2-o
Subject(s) - chemistry , imine , diastereomer , hydride , yield (engineering) , medicinal chemistry , cationic polymerization , moiety , crystal structure , aldimine , catalysis , stereochemistry , polymer chemistry , crystallography , organic chemistry , materials science , metallurgy , hydrogen
(Butadiene)zirconocene ( s ‐ trans ‐/ s ‐ cis ‐ 1 equilibrium mixture) reacts with the imine MeN=CHPh ( 7a ) to form the 1:1 carbon‐coupling product [κ N ‐MeN−CHPh−CH 2 −η 3 ‐(CHCHCH 2 )]ZrCp 2 ( 8a ). The X‐ray crystal structure analysis of 8a revealed a metallacyclic structure featuring a distorted π‐allyl moiety and a planar‐tricoordinate nitrogen atom. Only one of the two possible diastereoisomers is found in the crystal ( cis ‐ 8a ) as well as in solution. Treatment of 1 with the more bulky aldimine PhCH 2 N=CHPh ( 7b ) selectively gave the corresponding 1:1 addition product trans ‐ 8b . Ketimines PhCH 2 N=C(CH 2 ) 4 ( 7c ), HN=CPh 2 ( 7d ), or Δ 1 ‐2‐methylpyrroline ( 7e ) also reacted selectively with (butadiene)zirconocene to yield the analogous metallacyclic C−C coupling products 8c − e . Treatment of 8e with B(C 6 F 5 ) 3 proceeded cleanly by abstraction of a hydride anion from the carbon atom α to the nitrogen atom to form the intramolecularly coordinated imine product 10a {with the [HB(C 6 F 5 ) 3 − ] anion}. Similarly, Ph 3 C + abstracts a hydride ion from 8e to yield 10b {isolated with the [B(C 6 H 5 ) 4 − ] anion}. Proton addition from HNR 3 + reagents takes place selectively at the Zr−amido nitrogen atom of the complexes 8a or 8d to yield the substituted (π‐allyl)zirconocene cation complexes 11 or 12 , respectively, The cationic complexes 10 , 11 , and 12 polymerize ethene at room temperature/2 bar of ethene with moderate catalytic activities. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)