Alkoxides as ancillary ligands in organolanthanide chemistry: synthesis of, reactivity of, and olefin polymerization by the .mu.-hydride-.mu.-alkyl compounds [Y(C5Me5)(OC6H3tBu2)]2(.mu.-H)(.mu.-alkyl)

摘要: 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 (M Li, K) affords 5])(OAr)[l brace]CH(SiMe[sub 2][r brace] (3), which on subsequent hydrogenation (20 bar, 25[degree]C) gives the [mu]-H dimer [YC[sub 5](OAr)([mu]-H)][sub (4). Terminal olefins H[sub 2]C=CHR (R H, Me, Et, n-Bu) react regiospecifically and irreversibly 4 to give [mu]-n-alkyl species trans-[Y(C[sub 5])(OAr)][sub 2]([mu]-H)([mu]-CH[sub CH[sub 2]R) H (5), Me (6), Et (7), n-Bu (8)), respectively. [Y(C[sub 5])(OAr)([mu]-D)][sub (4-D) (prepared from 3 D[sub propene yields selectively only 2]([mu]-D)([mu]-CH[sub 2]C HDMe) (6-D), confirming nonreversibility olefin insertion. Compounds 4-8 polymerize ethene are single-component catalysts for polymerization [alpha]-olefins nonconjugated dienes. Dissolution in neat 1-hexene (to 8 situ) results slow yield poly(1-hexene) M[sub w] 15 700 w]/M[sub n] 1.67. cyclopolymerizes 1,5-hexadiene poly(methylene-1,3-cyclopentanediyl) rather than promotes cyclization methylenecyclopentane. The [mu]-alkyls 5-8 show diastereotopic [alpha]-CH[sub 3] resonances, implying idealized C[sub 2], 2v] geometry, indicates a mutually trans geometry themore » attendant 5] ligands. In 6, exchange two [alpha]]H[sub hydrogens by inversion at Y([mu]-C[sub 5])Y occurs [Delta]G* 11.1 [+-] 0.5 kcal mol[sup [minus]1] ([minus]25[degree]C), tert-butyl group equilibation same phenoxide 9.0 ([minus]93[degree]C). 60 refs., 1 fig., 2 tabs.« less