Zirconium Complexes That Contain a Diamido O-Donor Ligand with a Restricted Geometry

Abstract

Addition of LiNH(2,6-Me2C6H3) (LiNHAr‘) to cis-2,5-bis((tosyloxy)methyl)tetrahydrofuran gave cis-2,5-(Ar‘NHCH2)2(C4H6O) (H2[1]). The reaction between Zr(NMe2)4 and H2[1] yielded [1]Zr(NMe2)2, from which [1]ZrCl2 and [1]ZrMe2 were prepared readily. An unsymmetric relative of H2[1], cis-2,5-(Ar‘NHCH2)(ArNHCH2)(C4H6O) (H2[2]; Ar = 2,6-i-Pr2C6H3), was also prepared via the imine of 5-(hydroxymethyl)furaldehyde. Cations of the type {[1]ZrMe(PhNMe2)}[B(C6F5)4] and {[2]ZrMe(PhNMe2)}[B(C6F5)4], prepared in the reaction between the dimethyl species and [PhNHMe2][B(C6F5)4], could be observed and were stable toward exchange of free and coordinated dimethylaniline on the NMR time scale, while cations prepared in the reaction between the dimethyl species and [Ph3C][B(C6F5)4] did not have interpretable NMR spectra and appeared to be relatively unstable. Nevertheless, poly(1-hexene) that had a molecular weight approximately equal to the amount employed (up to 500 equiv) could be prepared by employing the latter at 0 °C in chlorobenzene.

Taming early transition metals: the use of polydentate amido-donor ligands to create well defined reactive sites in reagents and catalysts

“…9 the tridentate ligand may adopt either meridional or facial arrangements. 13,14,17,[30][31][32][33] Compounds 16 and 17 have been studied by Cloke, Horton and McConville and represent the two possible arrangements of the donor functions. 13,17,30 While complex 16 was found to be moderately active in ethylene polymerization, the procatalyst 17 displays high activity.…”

“…Compounds 18, 20 and 21 are active catalysts for the polymerization of hexene. 14,31,33 An important feature in these complexes is the absence of N-bonded silyl groups which are not only easily hydrolyzed but may undergo cyclometallations. The chemically robust nature of 18, 31 in particular, not only allows the living polymerization of hexene but has rendered the cationic intermediate suffiently stable to be characterized in solution.…”

“…This point is particularly apparent in the results of a comparative study of the catalytic properties of 21 and the simple dialkyl ether analogue [{O(CH 2 CH 2 NXyl) 2 ZrMe 2 ] 22. 33,35 Catalyst 21, which contains a conformationally more rigid and sterically more demanding tetrahydrofuran-derived diamido-donor ligand, produced polyhexene of almost twice the molecular weight as compound 22.…”

“Bidentate” and “tridentate” sulfonamide ligands for titanium complexes: crystal structures and solution dynamics elucidating an η2 or η3-coordination mode

“…Ethylene polymerization catalyzed by [(RNC 2 H 4 ) 2 O]TiR 2 in the presence of fluorinated boron compounds was extensively studied by Schrock and coworkers. 10,11 Attempted syntheses of dialkyl derivatives of 5 led to decomposition of the complexes, and exploration of highly active polymerization catalysts bearing tosylamide ligands is at present unsuccessful.…”

Non-Cp type homogeneous catalytic systems for olefin polymerization

“…Mechanistic studies [115][116][117][118][119][120] and immobilization [121][122][123][124] of the foregoing 5-coordinated precatalysts containing neutral bis(imino) pyridine ligands have been also carried out. [143].…”