CH3I in dichloromethane byproducts: I2; under N2, excess CH3I added to soln. of Nb complex in CH2Cl2, mixt. stirred at room temp. for 15 h during yellow product sepd.; solid filtered off, washed with CH2Cl2, dried in vac., elem. anal.;

HCl in tetrahydrofuran under N2, bubbling HCl gas through THF soln. of Nb complex;

in benzene under N2, soln. of Nb complex and hexafluorobut-2-yne in benzene stirred for 7 d at 40-50°C; concd. under vac., filtered, chromd., violet soln. concd., pentane added, kept at -60°C for 20 h, filtered, dried in vac., elem. anal.;