The ultimate aim of this experiment is to discover a novel and fundamental class of compounds containing guanidinate and orthonitridocarbonate anions (CN35- and CN48-). Motivated by the theoretical predictions we propose to explore a different high-pressure route to guanidinates and orthonitridocarbonates using reactions between elements and carbon-nitrogen compounds tetracyanoethylene (C6N4) and cyanuric triazide (C3N12). The synthesis will be performed in a laser-heated diamond anvil cells, while the products will be studied by means of multigrain single-crystal X-ray diffraction.