These observations suggest that the stability region for the 2:1 cocrystal is metastable and submerged within region 3. These resultsindicate that while the 1:1 cocrystal is a stable phase, the 2:1 complex is metastable, at 25 C, explaining why solution crystallization has not been successful. Interestingly, it appears that this situation is not true at the melting points since
in the binary phase diagram the 2:1 complex is a stable form. This raises the possibility that at higher temperatures in the ternary system the 2:1 cocrystal may be stable if a solvent of higher boiling point were used.