catena-Poly[[bis-(di-aqua-lithium)]-μ₄-3,3',5,5'-tetra-nitro-4,4'-bi-pyrazole-1,1'-diido]: a new moisture-insensitive alkali-metal energetic salt with a well-defined network structure.

ABSTRACT: In the structure of the title salt, [Li₂(C₆N₈O₈)(H₂O)₄]_n, the 3,3',5,5'-tetra-nitro-4,4'-bi-pyrazole-1,1'-diide dianion [{TNBPz}^2-] is situated across the twofold axis. The distorted coordination octa-hedra around Li⁺ involve four short bonds with two pyrazolate N atoms and two aqua ligands [Li-N(O) = 1.999 (3)-2.090 (2) Å] and two longer contacts with nitro-O atoms [2.550 (2), 2.636 (2) Å]. When combined with μ₄-{TNBPz}^2-, this generates a mono-periodic polymeric structure incorporating discrete centrosymmeric [(H₂O)₂Li-(di-nitro-pyrazolato)₂-Li(H₂O)₂] units. The three-dimensional stack of mutually orthogonal coordination chains is reminiscent of a Lincoln log pattern. It is influenced by conventional hydrogen bonding [O⋯O = 2.8555 (17)-3.0010 (15) Å] and multiple lone pair-π hole inter-actions of the nitro groups [N⋯O = 3.0349 (15) and 3.0887 (15) Å]. The Hirshfeld surface and two-dimensional fingerprint plots also support the significance of non-covalent bonding. Coordinative saturation and a favorable geometry at the Li⁺ ions, dense packing of the polymeric subconnectivities and particularly extensive inter-anion inter-actions may be involved in the stabilization of the structure. The title salt is a rare example of an energetic Li nitro-azolate, which nicely crystallizes from aqueous solution and is neither hygroscopic nor efflorescent. The TG/DTA data reveal total dehydration in the range of 330-430 K and stability of the anhydrous material up to 633-653 K.

SUBMITTER: Domasevitch KV 

PROVIDER: S-EPMC10439436 | biostudies-literature | 2023 Jun

REPOSITORIES: biostudies-literature