Polyhedral Clathrate Hydrates. XII. The Crystallographic Data on Hydrates of Ethylamine, Dimethylamine, Trimethylamine, n-Propylamine (Two Forms), iso-Propylamine, Diethylamine (Two Forms), and tert-Butylamine

Abstract

The crystallographic data for nine alkylamine hydrates are reported. The hydrates of C2H5NH2 and (CH3)2NH are isostructural with the 12 Å cubic gas hydrates and have unit cells with symmetries Pm3n and Pm3, and dimensions a=12.17 and 12.55 Å, respectively. Those of (CH3)3N and n-C3H7NH2 have symmetry P6/mmm and unit cell dimensions a=12.41 Å, c=12.50 Å and a=12.20 Å, c=12.38 Å, respectively, while that of iso-C3H7NH2 has symmetry P63/mmc and cell dimensions a=12.42 Å, c=25.22 Å. These hexagonal hydrates are related in their water structure to (iso-C5H11)4N+F−·38H2O. n-C3H7NH2 forms a second hydrate with monoclinic symmetry P21/n and unit cell dimensions a=12.58 Å, b=21.20 Å, c=17.47 Å, β=89.3°; (C2H5)2NH forms two hydrates, one of orthorhombic symmetry Pbcn and unit cell dimensions a=13.44 Å, b=11.77 Å, c=27.91 Å, and one of monoclinic symmetry P21/c and cell dimensions a=13.86 Å, b=8.44 Å, c=10.93 Å, β=97.5°; (CH3)3CNH2 forms a cubic hydrate with a unit cell of symmetry I4̄3d and dimensions a=18.81 Å. The total mass contents of the unit cells, calculated from the cell dimensions and experimental densities, are used to derive the probable stoichiometric formulas.