in pentane under N2, C5H6 in pentane treated with Sn compd. at -60°C, warmed to room temp.; distn.;

in pentane under N2, to Sn compd. in pentane t-BuOH added dropwise, stirred at room temp. for 30 min; evapd., sublimed at 60°C/0.001 Torr;