HCl in tetrahydrofuran byproducts: CO; React. of THF soln. of CpZr(CO)2(dmpe)Cl with C2H4, evolution of CO,; freezing of soln. (-196°C), addn. of anhydrous HCl, warming (room temp.), pptg. of pure solid CpZrCl3(dmpe), elem. anal., removal of cyclopentanol by evapn. and identification by GC-MS.;