magnesium metal; HgCl2 in tetrahydrofuran titanium complex in THF treated with magnesium powder followed by HgCl2, reaction mixture stirred vigorously under atmosphere of CO for 24 h; soln. concd. to dryness, residue extd. with heptane, extracts filtered under argon, filtrate concd. and cooled to -20°C;

CO in not given byproducts: C2H4; (inert), <5 atm CO; detected by NMR;

in hexane inert atmosphere; dissoln. of Ti-complex (under Ar), filtration, treatment with CO2 at room temp.; crystn. (6 h), decantation, washing (cold hexane), drying (vac.); secondcrop on crystn. of filtrate overnight; elem. anal.;

in further solvent(s) further solvent (liq. Xe), applying 3 bar CO at 173 K, warming up to 233K;