in hexane refluxed for 100 h; solvent was removed under vac., yellow solid was purified by sublimation;

in hexane refluxed for 100 h; solvent was removed under vac., yellow solid was purified by sublimation;

methyl iodide in tetrahydrofuran; hexane addn. of BuLi-soln. in hexane to W-complex in THF, stirring for 1 h; react. under inert atmosphere; evapn. (vacuum), column chromy. (elution with hexane), react. monitored by IR and NMR;