Tetracyanomethane under Pressure: Extended CN Polymers from Precursors with Built-in sp Centers.

Tetracyanomethane, C(CN), is a tetrahedral molecule containing a central sp carbon that is coordinated by reactive nitrile groups that could potentially transform to an extended CN network with a significant fraction of sp carbon. High-purity C(CN) was synthesized, and its physiochemical behavior was studied using in situ synchrotron angle-dispersive powder X-ray diffraction (PXRD) and Raman and infrared (IR) spectroscopies in a diamond anvil cell (DAC) up to 21 GPa. The pressure dependence of the fundamental vibrational modes associated with the molecular solid was determined, and some low-frequency Raman modes are reported for the first time.

Pressure-Induced Polymerization of LiN(CN).

The high-pressure behavior of lithium dicyanamide (LiN(CN)) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time.