Stereoregular polymerization of α-olefins catalyzed by chiral group 4 benzamidinate complexes of C₁ and C₃ symmetry

TY - JOUR

T1 - Stereoregular polymerization of α-olefins catalyzed by chiral group 4 benzamidinate complexes of C1 and C3 symmetry

AU - Averbuj, Claudia

AU - Tish, Edith

AU - Eisen, Moris S.

PY - 1998/9/2

Y1 - 1998/9/2

N2 - The chiral lithium (-)-trimethylsilylmyrtanyl amide reacts with benzonitrile yielding the chiral benzamidinate lithium ligand ([N- trimethylsilyl][N'-myrtanyl]benzamidinate Li-TMEDA (TMEDA = tetramethylethylenediamine), [N(R*)-C-N]Li. An X-ray study shows that the ligand has a distorted tetrahedral environment in which the lithium atom is arranged symmetrically between the two benzamidinate and the two TMEDA nitrogen atoms. Equimolar addition of [N(R*)-C-N]Li to TiCl4 in THF yields [N(R*)-C-N]-TiCl3·THF (1). An X-ray study of 1 shows that it has an octahedral structure with the oxygen atom and one chlorine atom at the apical positions. [N(R*)-C-N]3ZrCl·toluene (2) can be prepared in a manner related to that employed to synthesize 1. An X-ray study of 2 shows that it has a capped octahedral geometry with the three trimethylsilyl groups in a cis position with respect to the chlorine atom and the other three myrtanyl groups arranged On the opposite side of the chlorine. Addition of MeLi·LiBr to complex 2 yields [N(R*)-C-N]3ZrMe (3) which is obtained as cocrystalline with complex 2. The X-ray structure of the cocrystalline mixture is similar to that of the chloride complex 2 exhibiting a Zr-Me distance of 2.469(10) Å. Complex 1 is an active catalyst, under pressure, for the polymerization of propylene producing elastomeric polypropylene and for the syndiotactic polymerization of styrene. Complex 2 was found to be active for the highly stereospecific polymerization of propylene.

AB - The chiral lithium (-)-trimethylsilylmyrtanyl amide reacts with benzonitrile yielding the chiral benzamidinate lithium ligand ([N- trimethylsilyl][N'-myrtanyl]benzamidinate Li-TMEDA (TMEDA = tetramethylethylenediamine), [N(R*)-C-N]Li. An X-ray study shows that the ligand has a distorted tetrahedral environment in which the lithium atom is arranged symmetrically between the two benzamidinate and the two TMEDA nitrogen atoms. Equimolar addition of [N(R*)-C-N]Li to TiCl4 in THF yields [N(R*)-C-N]-TiCl3·THF (1). An X-ray study of 1 shows that it has an octahedral structure with the oxygen atom and one chlorine atom at the apical positions. [N(R*)-C-N]3ZrCl·toluene (2) can be prepared in a manner related to that employed to synthesize 1. An X-ray study of 2 shows that it has a capped octahedral geometry with the three trimethylsilyl groups in a cis position with respect to the chlorine atom and the other three myrtanyl groups arranged On the opposite side of the chlorine. Addition of MeLi·LiBr to complex 2 yields [N(R*)-C-N]3ZrMe (3) which is obtained as cocrystalline with complex 2. The X-ray structure of the cocrystalline mixture is similar to that of the chloride complex 2 exhibiting a Zr-Me distance of 2.469(10) Å. Complex 1 is an active catalyst, under pressure, for the polymerization of propylene producing elastomeric polypropylene and for the syndiotactic polymerization of styrene. Complex 2 was found to be active for the highly stereospecific polymerization of propylene.

UR - http://www.scopus.com/inward/record.url?scp=0032475419&partnerID=8YFLogxK

U2 - 10.1021/ja980392y

DO - 10.1021/ja980392y

M3 - 文章

AN - SCOPUS:0032475419

SN - 0002-7863

VL - 120

SP - 8640

EP - 8646

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 34

ER -