Triacidic Salts of Tris(aminomethyl)phosphines and Their Oxides

Tris(aminomethyl)phosphines and their oxides form triacidic salts that, unlike the free bases, are air-stable and non-hygroscopic. The salts of the unsubstituted compounds, (NH3 +CH2)3 P(O)n 3X−(3b: n = O, X = Br; 4a-c: n = 1, X = Cl, Br, or I), may be prepared directly from 1,3,5-triaza-7-phosphaadamantane (1) or its oxide (2) or from tris(N-carbomethoxylaminomethyl)phosphine oxide (9) by hydrolysis with the appropriate acid. The behaviour of the compounds towards acids and nucleophilic reagents is discussed.