in carbon disulfide slowly mixing solns. of excess PBr3 and Br2 in CS2 with continuous stirring (to avoid formation of PBr7);; after decanting, crystals are washed with CHCl3 on a filter of fritted glass and stored in absence of air;;

in neat (no solvent) reaction with excess Br2;;

in neat (no solvent) heating in sealed tube at 90°C;;

water in carbon disulfide shaking aq. soln. with CS2;;

water in carbon disulfide shaking aq. soln. with CS2;;