Synthesis of titanium, zirconium, and hafnium complexes that contain diamido donor ligands of the type [(t-BuN-o-C[sub 6]H[sub 4])[sub 2]O][sup 2[minus]] and an evaluation of activated versions for the polymerization of 1-hexene

Journal Article · Mon Aug 30 00:00:00 EDT 1999 · Organometallics

DOI:https://doi.org/10.1021/om9905005· OSTI ID:6100095

Schrock, R R; Baumann, R; Reid, S M; Goodman, J T; Stumpf, R; Davis, W M ^[1]

---

1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry

Titanium, zirconium, and hafnium dialkyl complexes that contain the [(t-Bu-d[sub 6]-N-o-C[sub 6]H[sub 4])[sub 2]O][sup 2[minus]] ([t-BuNON][sup 2[minus]]) ligand have been prepared. Only [T-BuNON]TiMe[sub 2] could be isolated, but [t-BuNON]ZrR[sub 2] and [t-BuNON]HfR[sub 2] complexes could be isolated in which (for example) R = Me, Et, or i-Bu. X-ray studies showed [t-BuNON]MMe[sub 2] structures (M = Tk or Zr) to be of the twisted fac variety in which two amido nitrogens occupy equatorial positions in a distorted trigonal bypyramid. However, in solution all such species show equivalent alkyl groups on the NMR time scale as a consequence of formation of an intermediate mer structure that contains a planar oxygen donor. In analogous complexes that contain the [l brace][Me(CD[sub 3])[sub 2]CNC[sub 6]H[sub 4]][Me(CD[sub 3])[sub 2]CN-2,4-Me[sub 2]C[sub 6]H[sub 2]]O[r brace][sup 2[minus]] or [l brace][Me(CD[sub 3])[sub 2]CNC[sub 6]H[sub 4]][Me(CD[sub 3])[sub 2]-N-2-EtC[sub 6]H[sub 3]]O[r brace][sup 2[minus]] ligand the two metal alkyl groups are inequivalent on the NMR time scale. Addition of trimethylphosphine to [t-BuNON]Zr(CH[sub 2]CH[sub 3])[sub 2] yields structurally characterized pseudooctahedral [t-BuNON]Zr([eta][sup 2]-C[sub 2]H[sub 4])(PMe[sub 3])[sub 2]. Addition of B(C[sub 6]F[sub 5])[sub 3] to [t-BuNON]ZrMe[sub 2] yields structurally characterized [l brace][t-BuNON]ZrMe[r brace][MeB(C[sub 6]F[sub 5])[sub 3]], while addition of [PhNMe[sub 2]H]-[B(C[sub 6]F[sub 4])[sub 4]] to [t-BuNON]ZrMe[sub 2] in bromobenzene-d[sub 5] generates [l brace][t-BuNON]ZrMe(PhNMe[sub 2])[r brace]-[B(C[sub 6]F[sub 5])[sub 4]], which is an active catalyst for the polymerization of up to 500 equiv of 1-hexene in a living manner at 0 C. The analogous hafnium systems are not as well behaved, since the dimethylaniline is insufficiently labile. No polymerization activity is observed for activated titanium dialkyl complexes. Polymerization activity is quenched upon addition of THF or dimethoxyethane to the cationic complexes. An X-ray structure of [l brace][t-BuNON]ZrMe(THF)[sub 2][r brace]-[B(C[sub 6]F[sub 5])[sub 4]] shows it to be a pseudooctahedral species in which the [t-BuNON][sup 2[minus]] ligand adopts a twisted mer geometry, while the X-ray structure of [t-BuNON]ZrMe(MeOCH[sub 2]CH[sub 2]OMe)-[B(C[sub 6]F[sub 5])[sub 4]] was found to be of the twisted fac variety. In the case of hafnium, pseudooctahedral cationic bis-THF or DME complexes can be isolated even when the anion is [B(C[sub 6]H[sub 5])[sub 4]][sup [minus]]; like all complexes that contain THF or DME they are essentially inactive for polymerization of 1-hexene.

• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-86ER13564
• OSTI ID: 6100095
• Journal Information: Organometallics, Journal Name: Organometallics Vol. 18:18; ISSN 0276-7333; ISSN ORGND7
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
AMINES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPLEXES
HAFNIUM COMPLEXES
HEXENES
HYDROCARBONS
LIGANDS
ORGANIC COMPOUNDS
POLYMERIZATION
SYNTHESIS
TITANIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
ZIRCONIUM COMPLEXES