The Crystal Structure of Hydrazinium Difluoride

An x‐ray analysis shows that crystalline hydrazinium difluoride is built upon a rhombohedral unit cell having a0=5.43A, α=38°10′, containing one molecular formula. The positions of the atoms have been determined and correspond to trans‐hydrazinium ions which form linear hydrogen bonds to fluoride ions at the corners of an elongated octahedron. Each fluoride ion forms three hydrogen bonds to different hydrazinium ions, and condenses the octahedra into continuous layers. As a result of the packing of these layers to build up the structure, each nitrogen atom comes in contact with an ``extra'' fluoride ion and thereby assumes a coordination number of 5. Analysis of the N–N and N–H≡F distances of 1.42A and 2.62A, respectively, shows that each atom in the hydrazinium ion bears approximately ¼ of a unit of positive charge. The bearing of the structure of the ion on the adjacent charge rule is discussed. Some of the properties of the ion are interpreted in terms of the structure.