ZIRCONIUM COMPLEXES INCORPORATING THE NEW TRIDENTATE DIAMIDE LIGAND [ME(3)SI)N(CH(2)CH(2)N(SIME(3)))(2)](2-)(L) - THE CRYSTAL-STRUCTURES OF [ZR(BH4)(2)L] AND [ZRCL(CH(SIME(3))(2))L]

The lithium complex of the sterically demanding, polyfunctional amide ligand [(Me3Si)N-{CH2CH2N(SiMe3)}2]2-, Li2L reached with [ZrCl4(thf)2] (thf = tetrahydrofuran) to form dimeric [(ZrCl2L)2] 2, in which the ligand is facially co-ordinated in a tridentate manner. Treatment of 2 with LiBH4 or Li[CH(SiMe3)2] generated [Zr(H3BH)L] 3 and [ZrCl{CH(SiMe3)2}L] 4, respectively. Variable-temperature NMR studies on 4 give evidence for restricted rotation of both the alkyl and amino SiMe3 groups. The crystal structures of 3 and 4 have been determined.