Metallocene derivatives of early transition metals .5. C-centered chiral metal alkyls, [MR*(Cl)(eta-C5H5)(2)], rac- and meso-[ZrR*(2)(eta-C5H5)(2)] [R* = CH(SiMe3)C6H4Me-o], and their one-electron reductions; reaction of Li[CH(SiMe3)(2)](Me2NCH2CH2NMe2) with [MCl2(eta-C5H5)(2)] (M = Zr or Hf)
Lappert, MF; Raston, CL; Skelton, BW; White, AH
| HERO ID | 1963371 |
|---|---|
| In Press | No |
| Year | 1997 |
| Title | Metallocene derivatives of early transition metals .5. C-centered chiral metal alkyls, [MR*(Cl)(eta-C5H5)(2)], rac- and meso-[ZrR*(2)(eta-C5H5)(2)] [R* = CH(SiMe3)C6H4Me-o], and their one-electron reductions; reaction of Li[CH(SiMe3)(2)](Me2NCH2CH2NMe2) with [MCl2(eta-C5H5)(2)] (M = Zr or Hf) |
| Authors | Lappert, MF; Raston, CL; Skelton, BW; White, AH |
| Journal | Journal of the Chemical Society. Dalton Transactions |
| Issue | 17 |
| Page Numbers | 2895-2902 |
| Abstract | The chloro(alkyl)metallocenes [MR*(Cl)(eta-C5H5)(2)][R*=-CH(SiMe3)C6H4Me-o; M=Zr 1 or Hf 2] have been prepared from [MCl2(eta-C5H5)(2)] and LiR*(tmen) (tmen=N,N,N',N'-tetramethylethane-1,2-diamine); further alkylation occurred only for M = Zr, affording rac-3a and meso-3b, [ZrR*(2)(eta-C5H5)(2)]. In contrast, reaction of 2 equivalents of Li[CH(SiMe3)(2)](tmen) with [ZrCl2(eta-C5H5)(2)] yielded an alkyl elimination product possessing mu-eta(1):eta(5)-C5H42- ligands. Compound 1 was reversibly reduced (E-1/2(red)=-1.72 V vs. saturated calomel electrode, SCE) whereas 2, 3a or 3b were irreversibly reduced (E-red=-2.12, -2.08, -2.00 V respectively vs. SCE). Thermolysis of 3b in toluene gave 3a (80 degrees C) or 'Zr(C10H8)' (120 degrees C). Photolysis of 3a or 3b at 20 OC in tetrahydrofuran (thf) yielded a 1 : 1 mixture of 3a and 3b; a d(1) intermediate has been unambiguously identified as [ZrR*(eta-C5H5)(2)]. Reduction of 1 (Na-Hg), or 3a and 3b (Na[C10H8]), in thf also gave [ZrR*(eta-C5H5)(2)] but this slowly transformed into [ZrR*(eta-C5H5)(2)(thf)], and 1 with Na[C10H8] and PPh3 gave [ZrR*(eta-C5H5)(2)(PPh3)]. Reduction of 1, 3a or3b or photolysis of 3a or 3b, in the presence of PMe3 gave [ZrR*(eta-C5H5)(2)(PMe3)]. Crystal structure determinations showed a slightly more crowded metal environment in 2 than in 1, consistent with the view that dialkylation in 2 is limited on steric grounds; M-sigma-C 2.359(4) (1), 2.322(8) (2), metal-centroid 2.22 (1), 2.21 (2), M-Cl 2.444(1) (1), 2.418(3) (2) Angstrom. The structure of 3a confirms the rac assignment, M-sigma-C 2.37(4), Angstrom, metal-centroid 2.23, 2.24 Angstrom. |
| Doi | 10.1039/a701586k |
| Wosid | WOS:A1997XW83900009 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |