in toluene under Ar, 2 equiv. of fulvene-compd., room temp. for 1 h, 65-70 °C for 4 h; evapn., Soxhlet extn. with hexane;

in tetrahydrofuran addn. of HfCl4 at 0°C to freshly prepared C5H4C3H7Li in THF withstirring over 0.5 h, mixture stirred for further 24 h at 20°C; THF removed under vac., residue extd. with boiling toluene and little activated charcoal, filtered, addn. of hexane to filtrate, cooling to -30°C, elem. anal.;