Elguero, J., C. Foces-Foces, et al. (1992). "Another possible carbon allotrope." Bull. Soc. Chim. Belg. 101: 795-799.

A new allotropic form of C formed by allene units is described. Its tetragonal unit cell contains 12 C atoms (8 sp2 and 4 sp) and it has a calcd. d. of 2.72 g.cm-3. As a result of the mixt. of sp2 and sp C atoms, this new all-C mol. is expected to be rather stable and may have metallic properties.