Zirconium complexes with amide ligands

A suitable entry into titanium and zirconium complex chemistry is the use of group IV amides and alkoxides. For example, when Ti(OEt)4 reacted with 2 equiv. of (roc)-2 in heptane, the titanium bis(disiloxide) 3 could be isolated in 91 % yield as a yellow microcrystalline material. Tbe results of the X-ray analysis (Fig. 1) of 3 confirm the expected extensive shielding of the titanium atom by the two sterically demanding disiloxide ligands. The geometry around the titanium atom is described best as distorted tetrahedral, with an 02-Til-02 chelate angle of 99° and an 02-T11-01 angle of 115.5°. 

Zirconium bis(amides) such as (35) and (36) display moderate ethylene polymerization activities.133,134 Complex (37) containing a chelating diamide ligand has been shown to initiate the living polymerization of a-olefins such as 1-hexene (Mw/Mn= 1.05-1.08) with activities up to 750gmmol-1 h-1.135-137 The living polymerization of propylene using this system activated with... 

Table 15 Complexes of Zirconium(IV) and Hafnium(IV) Halides with Sulfoxides, Selenoxides, Amides, Af-Oxides, P-Oxides and Related Ligands...

---