Gerken, Michael

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Browsing Gerken, Michael by Subject "Crystal structure"

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    Chalcogen versus dative bonding in [SF3] + Lewis acid−base adducts: [SF3(NCCH3)2] +, [SF3(NC5H5)2] +, and [SF3(phen)]+ (phen = 1,10-phenanthroline)
    (American Chemical Society, 2021) Turnbull, Douglas; Chaudhary, Praveen; Hazendonk, Paul; Wetmore, Stacey D.; Gerken, Michael
    The Lewis-acid behavior of [SF3][MF6] (M = Sb, As) salts toward mono- and bidentate nitrogen bases was explored. Reactions of [SF3][MF6] with excesses of CH3CN and C5H5N yielded [SF3(L)2]+ (L = CH3CN, C5H5N) salts, whereas the reaction of [SF3][SbF6] with equimolar 1,10-phenanthroline (phen) in CH3CN afforded [SF3(phen)][SbF6]·2CH3CN. Salts of these cations were characterized by low-temperature X-ray crystallography and Raman spectroscopy in the solid state as well as by 19F NMR spectroscopy in solution. In the solid state, the geometries of [SF3(NC5H5)2]+ and [SF3(phen)]+ are square pyramids with negligible cation–anion contacts, whereas the coordination of CH3CN and [SbF6]− to [SF3]+ in [SF3(NCCH3)2][SbF6] results in a distorted octahedral coordination sphere with a minimal perturbation of the trigonal-pyramidal SF3 moiety. 19F NMR spectroscopy revealed that [SF3(L)2]+ is fluxional in excess L at −30 °C, whereas [SF3(phen)]+ is rigid in CH2Cl2 at −40 °C. Density functional theory (DFT-B3LYP) calculations suggest that the S–N bonds in [SF3(NC5H5)2]+ and [SF3(phen)]+ possess substantial covalent character and result in a regular AX5E VSEPR geometry, whereas those in [SF3(NCCH3)2]+ are best described as S···N chalcogen-bonding interactions via σ-holes on [SF3]+, which is consistent with the crystallographic data.
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    Crystal structure of an ordered [WOF5]¯ salt: (1,10-phenH) [WOF5] (1,10-phen = 1, 10-phenanthroline
    (2020) Turnbull, Douglas; Gerken, Michael
    Crystals of 1,10-phenanthrolinium penta­fluorido­oxidotungstate(VI), (1,10-phen-H)[WOF5] (1,10-phen = 1,10-phenanthroline, C12H8N2), were obtained upon hydrolysis of WF6(1,10-phen) in CH3CN at 193 K. The (1,10-phen-H)[WOF5] salt contains a rare example of a [WOF5]− anion in which the oxygen and fluorine atoms are ordered. This ordering was verified by bond-valence determinations and structural comparisons with [Xe2F11][WOF5] and Lewis acid-base adducts of WOF4 with main-group donor ligands. The crystal packing is controlled by N—H⋯F hydrogen bonding that is directed exclusively to the axial F atom as a result of its increased basicity caused by the trans influence of the oxido ligand.
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    Syntheses, characterisation, and computational studies of tungsten hexafluoride adducts with pyridine and its derivatives
    (Elsevier, 2018) Turnbull, Douglas; Kostiuk, Nathan; Wetmore, Stacey D.; Gerken, Michael
    The reactions of WF6 with pyridine, 4-methylpyridine, 4-(dimethylamino)pyridine, and 4,4′-bipyridine (4,4′-bipy) in CH2Cl2 afford the Lewis-acid-base adducts WF6(4-NC5H4R) (R = H, CH3, N(CH3)2) and F6W(4,4′-bipy)WF6 as solids in quantitative yields. These adducts have been characterised in the solid state by Raman spectroscopy at ambient temperature and, in the cases of the mononuclear adducts, by X-ray crystallography at −173 °C. Furthermore, density-functional-theory (DFT-B3LYP) studies have been conducted to aid in predicting the structure of F6W(4,4′-bipy)WF6, assigning the vibrational frequencies of the adducts, and comparing their electronic properties.