The reaction of phosphorus pentaselenide with amines may yield, as products, selenophosphoric triamides, (RNH)3PSe; alkylammonium diselenophosphoric diamides, (RNH)2P(Se)Se−RNH3+; or alkylammonium monoacidbis(diselenophosphoric diamides), {[(RNH)2P(Se)Se]2H}−RNH3+, where R is an alkyl group. The preparation of potassium diselenophosphoric diamides, (RNH)2P(Se)Se−K+, is also described.