Bulky metal aryloxides, arylamides, and sulphur and phosphorus analogues. Part 1. Synthetic and chemical studies of titanium and zirconium aryloxides

Abstract

The synthesis and characterisation of several classes of aryloxides (OR) of Ti^IV, Ti^III, Zr^IV, and Li are described. Those of Ti^IV are of eight distinct classes: [Ti(OR)₄], [TiCl₂(OR)₂], [TiCl₂(OR)₂(thf)₂], [Ti(NMe₂)₂(OR)₂], [Ti(OMe)₂(OR)₂], [TiCl(OR′)(OR)₂], [TiCl(R′)(OR)₂], and [TiCl(η-C₅H₅)(OR)₂](R′= alkyl, thf = tetrahydrofuran); the Ti^III complexes are of types [{TiCl(OR)₂}_n] and [Ti(η-C₅H₅)₂(OR)]; the Zr^III complexes are of seven types: [ZrCl₂(OR)₂] and [Zr(η-C₅H₅)₂(OR)X], with X = OR, Cl, NMe₂, OMe, OC(O)NMe₂, or N(Ph)C(O)NMe₂; the new lithium aryloxides have formula [Li(OR)(OEt₂)]ⁿ. Most of the results relate to the ligands 2,6-Me₂C⁶H₃O^–, 2,6-Pri₂C₆H₃O^–, 2,6 Bu^t₂C₆H₃O^–, 4-Me-2,6-Bu^t₂C₆H₂O^–, 2,4,6-Bu^t₃C₆H₂O^–, 3,5-Bu^t₂C₆H₃O and 2,4-Bu^t₂C₆H₃O^–. The new complexes are readily soluble in diethyl ether and many also in hydrocarbons. Synthetic procedures include the following systems: (i) LiBuⁿ–ROH–OEt₂, for Li aryloxides; (ii) Ti^IV, Ti^III, or Zr^IV chlorides with [Li(OR)(OEt₂)]_n; (iii) for Ti^III, a redox reaction of type (ii) using a Ti^IV chloride as precursor; (iv) a Ti^IV or Zr^IV dimethylamide and ROH; and (v) for the ZrIV carbamate or Zr^IV urea, a CO₂ or PhNCO insertion into the appropriate Zr^IV dimethylamide.