ChemInform Abstract: POLYMORPHISM OF CRYSTALLINE POLY(HYDROXYMETHYL) COMPOUNDS. III. THE STRUCTURES OF CRYSTALLINE AND PLASTIC TRIS(HYDROXYMETHYL)AMINOMETHANE

The calculated and observed vibrational spectra of the ordered phase of tris(hydroxymethyl)aminomethane

“…developed by Shimanouchi [4]. The structure parameters for the C-, N-and 0-atoms have been taken from the X-ray study of Rudman [2]. It is worth mentioning a typographical error for the z-coordinate of H(21) in Table 4 which should be 0.1992 instead of 0.1192 as printed [S].…”

“…The shoulder at 3050 cm-' (only very weak in the infrared spectra of the polycrystalline sample [l]) now is assigned to the v (OH) mode of the O(1)-H-.0(2) contact. When raising the temperature from 100 K to 407 K (phase transition) neither changes in the interatomic distances R (O...O) [2], nor band shifts in the spectra can be observed.…”

“…Within each layer the three OH groups are connected by intermediate hydrogen bonds (interatomic distances are given in Table 3) whereas one of the amine hydrogen atoms is weakly hydrogen-bonded to the 0(1) atom of a molecule in an adjacent layer [2].…”

“…TRIS exhibits one solid-solid phase transition at 407 K to form an orientationally disordered crystalline (socalled plastic) phase [ 2 ] . It it of special interest because X-ray diffraction [2] and NMR studies [S] suggest that the hydrogen bonds present in the ordered phase also play a dominant role in the plastic state. This is unusual as in most of the plastic phases the molecules rotate quite easily while their centres of mass remain fixed in a lattice.…”