TITANOCENE SYNTHESIS This application is a continuation of United States application Serial No. 09/880,289 filed 13 June 2001, which in turn is a continuation-in-part of United States application Serial No. 09/784,736 filed 15 February 2001 (now United States patent 6,307,063 B1 issued 23 October 2001).

FIELD OF THE INVENTION This invention relates to titanium-trihalide complexes free from contamination with salts of metals other than titanium. More particularly, the invention relates to the synthesis of such adducts and to the conversion thereof to titanocenes.

BACKGROUND OF THE INVENTION Application Serial No. 09/784,736 describes a method for converting a Ti (IV) compound to a complex of a Ti (III) compound free of foreign metal contaminations. A preferred embodiment of the invention entails the reduction of TiCl4 with particulate titanium in the presence of a reagent which forms a titanium trichloride complex insoluble in the reduction reaction mixture. According to that application, the consequent titanium trichloride complex may be converted to a titanocene in known manner. See, e. g., United States patent 6,218,557.

SUMMARY OF THE INVENTION This invention provides methods for the conversion to titanocenes of the titanium trichloride complex as described in application Serial No. 09/784,736.

DETAILED DESCRIPTION OF THE INVENTION The invention may comprise a first step in which a titanium trichloride complex free of contamination with salts of other metals is produced. A second step of this invention may comprise treatment of a ligand with the titanium trichloride complex product of the first step to produce a titanocene.

EXAMPLE 1 One example illustrative of the first step is to charge a flask with particulate titanium (~100 mesh, 0.25 mole, 11.9 g) and dimethoxyethane (DME) (2 kg).

With cooling slowly, add titanium tetrachloride (0.77 mole, 146.3 g), maintaining temperature at 0°C. After addition is complete, slowly warm to reflux, and hold at reflux for 8 hours. Cool to room temperature and filter. The cake comprises a TiCl3-DNE complex which is free of contamination with any salt of a metal other than titanium. Dry the cake in vacua. Yield = 246 g; 85%, based on total charge of titanium (both TiCl4 and particulate titanium).

Analysis: Ti = 16.6% Cl = 36.6% Theoretical: Ti = 16.5% Cl = 36.7% Product is aluminum and magnesium free.

As explained in United States application Serial No. 09/784,736, the reduction reaction may optionally be conducted in a medium comprising the complex-forming reagent per se or in such combination with any non- interfering medium. Suitable media include aliphatic and aromatic hydrocarbons; aromatic hydrocarbons are preferred.

Compounds which form a complex with Ti (III) compounds are known. See German patent application DE 197 39 946 Al published March 18,1999. Each such complex-forming compound which yields a Ti (III) complex insoluble in the TiCl4 reduction reaction mixture is useful in this invention. Preferred complex-forming compounds are ethers, typically tetrahydrofuran (THF) and DME.

Another aspect of the invention may include conversion of the Ti (III) complexes to metallocenes, which are also free of contamination with the salts of metals other than titanium, useful as olefin polymerization catalyst ligands, as olefin polymerization catalysts per se, or as components of olefin polymerization catalyst systems.

EXAMPLE 2 This example is a general illustration of the second step of the invention. The TiCl3'DME complex as produced in Example 1 is used instead of the TiCl3 per se in each or any of the relevant examples of United States patent 6, 218, 557 to produce a titanocene.