in dichloromethane byproducts: cis-stilbene, E-stilbene; further products; under N2, stirring of a soln. of the W-complex at room temp. for 2 h;; evapn. of the solvent in vac., dissolving (pentane/CH2Cl2), chromy. (-25°C, silica gel, pentane/CH2Cl2);;