Phase transition and crystal structures of adamantane

Abstract

The -65 °C phase transition in adamantane, C10H16, involves a change from the face centered cubic room-temperature structure to a tetragonal structure, space group PTt21c, with a=6-60, c=8-81 /~ and Z=2. The low-temperature cell is related to the cubic cell by atetr~-acubic/)/2 and ctetr-~aeubic. A single-crystal X-ray study of the low-temperature phase at -110 °C shows the arrangement of the molecules to be unchanged except for a 9 ° tilt about the c axis. A redetermination of the room-temperature structure using single-crystal data supports a disordered structure, space group Fm3m, rather than the previously assumed, ordered, F]3m structure.

Comparison between structural analyses of plastic and brittle crystals

“…(2) Lattice parameters (Table 1) The low-temperature phase of adamantane crystallizes in the tetragonal system with the P421c space group in agreement with the previous determination (Nordman & Schmitkons, 1965). 25 reflections were used to determine lattice parameters, sin 0/A-0"30 A -l.…”

“…The refinements were performed in two ways, starting from the known structure (Nordman & Schmitkons, 1965). At first the atoms were considered independent.…”

“…The structure of the ordered phase of adamantane has already been investigated at 163 K with X-ray precession photographs (Nordman & Schmitkons, 1965). However, with the 'poor and deteriorating quality of the diffraction patterns', only 53 independent reflections were evaluated and therefore the atomic positions and thermal parameters were not refined in an accurate way.…”

Crystal and molecular structure of 2-aminoadamantane-2-carboxylic acid hydrobromide

“…The structure of adamantane (C10H16) has been reported by Nordman & Schmitkons (1965) both at room and at low temperature. It undergoes a phase transition at -65°C, changing from face-centred cubic to a tetragonal low-temperature form.…”

The crystal and molecular structure of hexacyclo[10,3,1,02,10,03,7,06,16,09,14]hexadecane, an ethano-bridged diamantane

“…A preliminary communication on this investigation including details of the chemical reactions has already been published (Rao, Sundaralingam, Osawa, Wiskott & Schleyer, 1970). The crystal structures of four other cage hydrocarbons, congressane (Karle & Karle, 1965), adamantane (Nordman & Schmitkons, 1965), diadamantane (Alden, Kraut & Taylor, 1968) and tetramantane (Schleyer, Osawa & Drew, 1968) have been determined to date. In the former two cases the molecules occupy a special position in the lattice and thus are constrained to the corresponding symmetry.…”