Gerken, Michael

Permanent URI for this collection

https://opus.uleth.ca/handle/10133/5926

Browse

Browsing Gerken, Michael by Subject "Chalcogens"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Synthesis and characterization of adducts between SF4 and oxygen bases: examples of O···S(IV) chalcogen bonding
    (American Chemical Society, 2016) Goettel, James T.; Gerken, Michael
    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.
  • Thumbnail Image
    Item
    Synthesis and characterization of SF4 adducts with polycyclic amines
    (American Chemical Society, 2020) Kostiuk, Nathan; Goettel, James T.; Gerken, Michael
    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.