Synthesis and Characterization of Adducts between SF₄ and Oxygen Bases: Examples of O···S(IV) Chalcogen Bonding

Lewis acid–base adducts between SF₄ and the oxygen bases tetrahydrofuran, cyclopentanone, and 1,2-dimethoxyethane were synthesized and characterized by Raman spectroscopy and X-ray crystallography. Crystal structures of (SF₄·OC₄H₈)₂, SF₄·(OC₄H₈)₂, SF₄·CH₃OC₂H₄OCH₃, and SF₄·(OC₅H₈)₂ show weak S···O chalcogen bonding interactions ranging from 2.662(2) to 2.8692(9) Å. Caffeine, which has three Lewis basic sites, was reacted with SF₄ and one aliquot of HF forming C₈H₁₀N₄O₂·2SF₄·HF, which was also characterized by X-ray crystallography. Density functional theory calculations aided in the assignment of the vibrational spectra of (SF₄·OC₄H₈)₂, SF₄·(OC₄H₈)₂, SF₄·CH₃OC₂H₄OCH₃, and SF₄·(OC₅H₈)₂. Bonding was studied by natural bond order and the quantum theory of atoms in molecules analyses

Syntheses and Characterization of W(NC₆F₅)F₅^– and W₂(NC₆F₅)₂F₉^– Salts and Computational Studies of the W(NR)F₅^– (R = H, F, CH₃, CF₃, C₆H₅, C₆F₅) and W₂(NC₆F₅)₂F₉^– Anions

Convenient preparative routes to fluorido­[(pentafluorophenyl)­imido]­tungstate­(VI) salts have been developed. The reaction of WF₆·NC₅H₅ or [N­(CH₃)₄]­[WF₇] with C₆F₅NH₂ results in quantitative formation of the C₅H₅NH⁺ or N­(CH₃)₄⁺ salt of the W­(NC₆F₅)­F₅^– anion, respectively. The dissolution of [C₅H₅NH]­[W­(NC₆F₅)­F₅] in anhydrous HF results in the formation of [C₅H₅NH]­[W₂(NC₆F₅)₂F₉]. These salts have been comprehensively characterized in the solid state by X-ray crystallography and Raman spectroscopy and in solution by ¹⁹F and ¹H NMR spectroscopy. The crystal structures of the W­(NC₆F₅)­F₅^– salts reveal conformational differences in the anions, and the ¹⁹F NMR spectra of these salts in CH₃CN reveal coupling of the axial fluorido ligand to the ¹⁴N nucleus of the imido ligand. In addition, density functional theory (DFT-B3LYP) calculations have been performed on a series of W­(NR)­F₅^– anions (R = H, F, CH₃, CF₃, C₆H₅, C₆F₅) and the W₂(NC₆F₅)₂F₉^– anion, including gas-phase geometry optimizations, vibrational frequencies, molecular orbitals, and natural bond orbital (NBO) analyses

Interactions between SF₄ and Fluoride: A Crystallographic Study of Solvolysis Products of SF₄·Nitrogen-Base Adducts by HF

Adducts between SF₄ and a nitrogen base are easily solvolyzed by HF, yielding the protonated nitrogen base and fluoride. Salts resulting from the solvolysis of SF₄·NC₅H₅, SF₄·NC₅H₄(CH₃), SF₄·NC₅H₃(CH₃)₂, and SF₄·NC₅H₄N­(CH₃)₂ have been studied by Raman spectroscopy and X-ray crystallography. Crystal structures were obtained for pyridinium salts [HNC₅H₅⁺]­F^–·SF₄ and [HNC₅H₅⁺]­F^–[HF]·2SF₄, the 4-methylpyridinium salt [HNC₅H₄(CH₃)⁺]­F^–·SF₄, the 2,6-methylpyridinium salt [HNC₅H₃(CH₃)₂⁺]₂[SF₅^–]­F^–·SF₄, and 4-(dimethylamino)­pyridinium salts [HNC₅H₄N­(CH₃)₂⁺]₂[SF₅^–]­F^–·CH₂Cl₂ and [NC₅H₄N­(CH₃)₂⁺]­[HF₂^–]·2SF₄. In addition, the structure of [HNC₅H₄(CH₃)⁺]­[HF₂^–] was obtained. 4,4′-Bipyridyl reacts with SF₄ and 1 and 2 equiv of HF to give the 4,4′-bipyridinium salts [NH₄C₅–C₅H₄NH⁺]­F^–·2SF₄ and [HNH₄C₅–C₅H₄NH²⁺]­2F^–·4SF₄, respectively. These structures exhibit a surprising range of bonding modalities and provide an extensive view of SF₄ and its contacts with Lewis basic groups in the solid state. The interactions range from the strong F₄S–F^– bond in the previously observed SF₅^– anion to weak F₄S---F^–, F₄S­(---F^–)₂, and F₄S­(---FHF^–)₂ dative bonds

Fluoride-Ion Acceptor Properties of WSF₄: Synthesis, Characterization, and Computational Study of the WSF₅^– and W₂S₂F₉^– Anions and ¹⁹F NMR Spectroscopic Characterization of the W₂OSF₉^– Anion

The new [N­(CH₃)₄]­[WSF₅] salt was synthesized by two preparative methods: (a) by reaction of WSF₄ with [N­(CH₃)₄]­[F] in CH₃CN and (b) directly from WF₆ using the new sulfide-transfer reagent [N­(CH₃)₄]­[SSi­(CH₃)₃]. The [N­(CH₃)₄]­[WSF₅] salt was characterized by Raman, IR, and ¹⁹F NMR spectroscopy and [N­(CH₃)₄]­[WSF₅]·CH₃CN by X-ray crystallography. The reaction of WSF₄ with half an aliquot of [N­(CH₃)₄]­[F] yielded [N­(CH₃)₄]­[W₂S₂F₉], which was characterized by Raman and ¹⁹F NMR spectroscopy and by X-ray crystallography. The WSF₅^– and W₂S₂F₉^– anions were studied by density functional theory calculations. The novel [W₂OSF₉]⁻ anion was observed by ¹⁹F NMR spectroscopy in a CH₃CN solution of WOF₄ and WSF₅^–, as well as CH₃CN solutions of WSF₄ and WOF₅^–

Additional file 3: Table S2. of Tumour stage distribution and survival of malignant melanoma in Germany 2002–2011

Malignant melanoma patients aged 35 years and above by age at diagnosis, sex, UICC stage, year of diagnosis, place of residence and ‘diagnosis during screening’, N = 34 739 (UICC 0 and X excluded) (DOCX 40 kb

Additional file 4: Table S3. of Tumour stage distribution and survival of malignant melanoma in Germany 2002–2011

Relative 5-year survival of malignant melanoma patients diagnosed between 2002 and 2011, overall (UICC 0-IV, X) (N = 60 672) and for patients with invasive tumours (UICC I – IV, X) stratified by age, sex, UICC stage, ‘diagnosis during screening’ and place of residence (N = 49 351) (DOCX 39 kb