The Hydrazyl Anion

Other names Diazanide, hydrazide, hydrazinide CAS Registry Number [25415-88-7] 

Formation. The only known hydrazides isolated are the probably ionic compound NaN2H3 (see Natrium 1928, pp. 260/1 and Natrium Erg.-Bd. 3, 1966, pp. 928/9) and the more covalent compound Zn(N2H3)2- The hydrazides are formed by the reaction of anhydrous N2H4 with metallic Na and Zn(C2HsO)2, respectively. NaN2H3 is extremely unstable and explosive Zn(N2H3)2 is more stable, but hydrolyzes within a few seconds [1]. 

Structure and Properties. From ab initio calculations [2 to 4] a nonplanar structure with Cg symmetry, i.e., a staggered configuration of the NH2 group to the NNH plane, was predicted to be the most stable form of the anion. This structure also followed from an analysis of the vibrational spectrum of the anion [5]. Bond distances (in A) and angles (in °) were obtained by ab initio calculations at the 4-31G level (for atom numbering, see p. 75)  

Theoretical studies were performed on the topomerization of the anion [2, 4, 6]. A complete topomerization of the anion requires both planar inversion and rotation around the N-N bond. The sum of the barriers of the consecutive processes, rotation (33.9 kJ/mol [2, 4]) and inversion (31.4 kJ/mol [4]), is lower than the barrier for the simultaneous interconversion (72.05 kJ/mol) for details, see [4, 6]. 

A proton affinity for N2H3 of 1820 kJ/mol was obtained from ab initio calculations [2]. 

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