P(N(C2H5)2)3 in dichloromethane saturation of a stirred soln. of borane in CH2Cl2 with gaseous CF3Br at 0°C and then dropwise addn. of P(NEt2)3 through which a stream of CF3Br passed, stirring for 1 h at room temp.; solvent removal, treating of residue with conc. HCl;