Carbon nitride coatings are synthesized in the new laser plasma of powerful optical pulsating discharge using acetonitrile as a precursor. A high-pressure and -temperature C3N4 cubic phase with a spinel structure type is obtained. The microhardness of coatings of this structure type is ~45 gPa. The chemical composition and structure of the coatings are characterized by a complex of spectroscopic (IR, Raman, EDS) techniques as well as microscopic (AFM and XRD) techniques.