1: selenium With sodium tetrahydroborate in ethanol T=20°C; 1 h; Inert atmosphere; 2: (4-cyano-phenyl)boronic acid With 1,10-phenanthroline; CuSO4‵5H2O; oxygen in ethanol T=20°C; 10 h;

Na2Se2 in water T=4 - 40°C;

electrolysis at -1.55 V, Pt grid electrodes;