in toluene Irradiation (UV/VIS); (Ar); addn. of fumaronitrile to soln. of W-compd. in toluene portionwise, irradn. (500 W Hg-lamp, >550 nm, 62 h), pptn.; decantation of supernatant, washing (toluene), drying in vac.; elem. anal., detn. of isomeric ratio of CNCH=CHCN ligand fumaronitrile/maleonitrile 3:2 by (1)H-NMR spectroscopy;
