Tetrazoles. Part 36. Synthesis, Structure and Properties of 5-Nitrotetrazole.-The free 5-nitrotetrazole (II) is prepared for the first time by reaction of sodium 5-nitrotetrazolate (I) with sulfuric acid. A detailed quantum-chemical calculation of the electronic structure and some physico-chemical constants of 5-nitrotetrazole is presented. Compound (II) is shown to undergo regioselective alkylation and addition of olefins at the N 2 -position to give the 2-alkyl derivatives (IV) and (IX), respectively. With formaldehyde, the 2-hydroxymethyl derivative (XII) is formed which, despite the electron accepting 5-nitro group, undergoes alcohol-typical reactions. The 2-substituted 5-nitrotetrazoles (IV), (IX) and (XII) are shown to undergo several modifications at the 2-substituent to afford novel 5-nitrotetrazole analogues. -(KOLDOBSKII, G. I.; SOLDATENKO, D. S.; GERASIMOVA, E. S.; KHOKHRYAKOVA, N. R.; SHCHERBININ, M. B.; LEBEDEV, V. P.; OSTROVSKII, V. A.; Zh.