in pentane W2(i-Pr)2(NMe2)4/pentane soln. was cooled to 0°C. Addn. of 4.1 equiv. of isopropanol; stirring; degassed(HNMe2); after 45 min. addn. of 2.1 equiv. of 2-pentyne at 0°C; stirred 45 min.. Cooled to -20°C; After 12h crystals were harvested by removing of the supernatant liquid and drying in vacuo. Elem. anal. and detected by NMR;