Alkoxides as ancillary ligands in organolanthanide chemistry. Synthesis of, reactivity of, and olefin polymerization by the [mu]-hydride-[mu]-alkyl compounds [Y(C[sub 5]Me[sub 5])(OC[sub 6]H[sub 3][sup t]Bu[sub 2])][sub 2]([mu]-H) ([mu]-alkyl)
- Koninklijke/Shell-Lab., Amsterdam (Netherlands)
Reaction of Y(C[sub 5]Me[sub 5])(OAr)[sub 2] (2; OAr = 0.2,6-C[sub 6]H[sub 3][sup t]Bu[sub 2]) with MCH(SiMe[sub 3])[sub 2] (M = Li, K) affords Y(C[sub 5]Me[sub 5])(OAr)[l brace]CH(SiMe[sub 3])[sub 2][r brace] (3), which on subsequent hydrogenation (20 bar, 25[degree]C) gives the [mu]-H dimer [YC[sub 5]Me[sub 5](OAr)([mu]-H)][sub 2] (4). Terminal olefins H[sub 2]C=CHR (R = H, Me, Et, n-Bu) react regiospecifically and irreversibly with 4 to give the [mu]-n-alkyl species trans-[Y(C[sub 5]Me[sub 5])(OAr)][sub 2]([mu]-H)([mu]-CH[sub 2] CH[sub 2]R) (R = H (5), Me (6), Et (7), n-Bu (8)), respectively. Reaction of [Y(C[sub 5]Me[sub 5])(OAr)([mu]-D)][sub 2] (4-D) (prepared from 3 and D[sub 2]) with propene yields selectively only trans-[Y(C[sub 5]Me[sub 5])(OAr)][sub 2]([mu]-D)([mu]-CH[sub 2]C HDMe) (6-D), confirming the nonreversibility of olefin insertion. Compounds 4-8 polymerize ethene and are single-component catalysts for the polymerization of [alpha]-olefins and nonconjugated dienes. Dissolution of 4 in neat 1-hexene (to give 8 in situ) results in slow polymerization to yield poly(1-hexene) with M[sub w] = 15 700 and M[sub w]/M[sub n] = 1.67. 4 cyclopolymerizes neat 1,5-hexadiene to poly(methylene-1,3-cyclopentanediyl) rather than promotes cyclization to methylenecyclopentane. The [mu]-alkyls 5-8 show diastereotopic [alpha]-CH[sub 3] resonances, implying idealized C[sub 2], rather than C[sub 2v] geometry, which indicates a mutually trans geometry for the attendant C[sub 5]Me[sub 5] and OAr ligands. In 6, exchange of the two diastereotopic C[sub [alpha]]H[sub 2] hydrogens by inversion at Y([mu]-C[sub 5])Y occurs with [Delta]G* = 11.1 [+-] 0.5 kcal mol[sup [minus]1] ([minus]25[degree]C), and tert-butyl group equilibation on the same phenoxide occurs with [Delta]G* = 9.0 [+-] 0.5 kcal mol[sup [minus]1] ([minus]93[degree]C). 60 refs., 1 fig., 2 tabs.
- OSTI ID:
- 5042248
- Journal Information:
- Organometallics; (United States), Vol. 13:1; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKENES
POLYMERIZATION
ORGANOMETALLIC COMPOUNDS
CHEMICAL REACTIONS
SYNTHESIS
YTTRIUM COMPOUNDS
ALKOXIDES
AROMATICS
CATALYSTS
HYDROGENATION
LIGANDS
NUCLEAR MAGNETIC RESONANCE
THERMODYNAMICS
HYDROCARBONS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
RESONANCE
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures