Complexes of Nitrilotriacetic Acid with Amines. Molecular Structures of 2-Ammonioethanol Nitrilotriacetate and Bis{2-Ammonio-2-(Hydroxymethyl)propane-1,3-Diol} Nitrilotriacetate

Reactions of nitrilotriacetic acid with 2-aminoethanol, 2-amino-2-(hydroxymethyl)propane-1,3-diol, and 2,2'-(ethylenedioxy)bis(ethylamine) afford the following salts in high yields: 2-ammonioethanol nitrilotriacetate [HN+(CH2COO–)2(CH2COOH) ⋅ H3N+CH2CH2OH]n, bis{2-ammonio-2-(hydroxymethyl)propane-1,3-diol} nitrilotriacetate HN+(CH2COO–)3 ⋅ 2H3N+C(CH2 OH)3, and 2,2'-(ethylenedioxy)bis(ethylammonium) nitrilotriacetate HN+(CH2COO–)3 ⋅ H3N+CH2CH2OCH2CH2OCH2CH2N+H3. The molecular structures of 2-ammonioethanol nitrilotriacetate and bis{2-ammonio-2-(hydroxymethyl)propane-1,3-diol} nitrilotriacetate were determined. Nitrilotriacetic acid molecules in 2-ammonioethanol nitrilotriacetate are linked by O⋅⋅⋅H⋅⋅⋅O hydrogen bonds involving acid groups of adjacent molecules to form a polymer chain. On the contrary, nitrilotriacetic acid molecules in bis{2-ammonio-2-(hydroxymethyl)propane-1,3-diol} nitrilotriacetate do not form polymer chains. In the crystals of both compounds, adjacent molecules are linked by numerous O⋅⋅⋅H interactions to form infinite 3D frameworks.