New and versatile routes to zirconium imido dichloride compounds

Reactions of zirconium dialkyl- or bis(amido)-dichloride complexes "Zr(CH2SiMe3)2Cl2(Et2O)2]" or Zr(NMe2)2Cl2(THF)2] with primary alkyl and aryl amines are described. Reaction of "Zr(CH2SiMe3)2Cl2(Et2O)2]" with RNH2 in THF afforded dimeric Zr2(mu-NR)2Cl4(THF)4](R=2,6-C6H3iPr2 (1), 2,6-C6H3Me2 (2) or Ph (3)), Zr2(mu-NR)2Cl4(THF)3](R=tBu (5), iPr (6), CH2Ph (7)), or the "ate" complex Zr2(mu-NC6F5)2Cl6(THF)2{Li(THF)3}2](4, the LiCl coming from the in situ prepared "Zr(CH2SiMe3)2Cl2(Et2O)2]"). With Zr(NMe2)2Cl2(THF)2] the compounds Zr2(mu-NR)2Cl4(L)x(L')y](R=2,6-C6H3iPr2 (8), 2,6-C6H3Me2 (9), Ph (10) or C6F5 (11); (L)x(L')y=(NHMe2)3(THF), (NHMe2)2(THF)2 or undefined), Zr2(mu-NtBu)2Cl4(NHMe2)3] (12) and insoluble Zr(NR)Cl2(NHMe2)]x(R=iPr (13) or CH2Ph (14)) were obtained. Attempts to form monomeric terminal imido compounds by reaction of or with an excess of pyridine led, respectively, to the corresponding dimeric adducts Zr2(mu-2,6-C6H3Me2)2Cl4(py)4] (15) and Zr2(mu-NtBu)2Cl4(py)3] (16). The X-ray structures of 1, 2, 4, 8, 12 and 15 have been determined.