Synthesis and Characterization of SF₄ Adducts with Polycyclic Amines

Abstract

Chalcogen-bonding interactions of SF₄ with the polycyclic amines DABCO (C₆H₁₂N₂) and HMTA (C₆H₁₂N₄) were studied by low-temperature Raman spectroscopy and X-ray crystallography, revealing the 2:1 adducts C₆H₁₂N₂·2SF₄ and C₆H₁₂N₄·2SF₄ obtained from SF₄ solvent. In C₆H₁₂N₂·2SF₄, the sulfur in each SF₄ molecule is pentacoordinate with each SF₄ coordinated by a single amine group, whereas C₆H₁₂N₄·2SF₄ forms a one-dimensional coordination polymer with three of the four nitrogen atoms in HMTA exhibiting N---S chalcogen bonds: one terminal N---SF₄ and one experimentally unprecedented bridging N---(SF₄)---N moiety. Solvolysis of C₆H₁₂N₂·2SF₄ by HF yielded crystals of [C₆H₁₂N₂H]⁺₂F^-[SF₅]^-·6SF₄, in which SF₄ acts as a chalcogen-bond donor toward N as well as F. Solvolysis of C₆H₁₂N₄·2SF₄ resulted in the formation of the monoprotonated HMTA salt [C₆H₁₂N₄H]⁺[HF₂]^-·SF₄. Excess HF also led to isolation of monoprotonated HTMA, as seen in the crystal structure of the [C₆H₁₂N₄H]⁺[H₂F₃]^-·HF salt. The reaction of bicyclic, monobasic quinuclidine with SF₄ and HF gave [C₇H₁₃NH]⁺F^-·3.5SF₄, which contains N-H---F^----SF₄ interactions, as well as an interstitial, disordered SF₄ molecule.