The reaction of ZrCl4(dmpe)2 [dmpe = 1,2-bis(dimethylphosphino)ethane] with excess MgMe2 gives the dialkyldichloro-complex ZrMe2Cl2(dmpe)2, whereas interaction with excess LiMe gives the tetra-alkyl ZrMe4(dmpe)2. N.m.r. data indicate a rigid structure for the latter molecule at -60 °C, while the X-ray crystal structure shows the molecule, which has crystallographic C2 symmetry, to have dodecahedral geometry with the methyl groups at the (B) sites and the phosphines at the (A) sites: Zr-C 2.440(6), Zr-P 2.814(1) Å. Alkylation of ZrCl4(dmpe)2 with excess LiCH2SiMe3 leads to the six-co-ordinate complex Zr(CH2SiMe3)4(dmpe); the analogous compound Zr(CH2Ph)4(dmpe) can be prepared from Zr(CH2Ph)4 and dmpe. The X-ray crystal structure of Zr(CH2Ph)4(dmpe) shows a severely distorted octahedral geometry consisting of three σ-benzyl groups and one partially π-bonded benzyl group: Zr-C(σ) 2.264(7)-2.368(5), Zr-Cα(π) 2.359(6), Zr ⋯ Cβ(π) 2.788(8), Zr-P 2.862(4), 2.885(4) Å. The preparations and characterizations of some hafnium analogues are also described.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|State||Published - Dec 1 1984|
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