Premium
Multinuclear Solid‐State Magnetic Resonance as a Sensitive Probe of Structural Changes upon the Occurrence of Halogen Bonding in Co‐crystals
Author(s) -
Widdifield Cory M.,
Cavallo Gabriella,
Facey Glenn A.,
Pilati Tullio,
Lin Jingxiang,
Metrangolo Pierangelo,
Resnati Giuseppe,
Bryce David L.
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300809
Subject(s) - halogen , halogen bond , solid state , nuclear magnetic resonance , solid state nuclear magnetic resonance , materials science , magnetic resonance imaging , chemistry , crystallography , organic chemistry , physics , medicine , alkyl , radiology
Although the understanding of intermolecular interactions, such as hydrogen bonding, is relatively well‐developed, many additional weak interactions work both in tandem and competitively to stabilize a given crystal structure. Due to a wide array of potential applications, a substantial effort has been invested in understanding the halogen bond. Here, we explore the utility of multinuclear ( 13 C, 14/15 N, 19 F, and 127 I) solid‐state magnetic resonance experiments in characterizing the electronic and structural changes which take place upon the formation of five halogen‐bonded co‐crystalline product materials. Single‐crystal X‐ray diffraction (XRD) structures of three novel co‐crystals which exhibit a 1:1 stoichiometry between decamethonium diiodide (i.e., [(CH 3 ) 3 N + (CH 2 ) 10 N + (CH 3 ) 3 ][2 I − ]) and different para ‐dihalogen‐substituted benzene moieties (i.e., p ‐C 6 X 2 Y 4 , X=Br, I; Y=H, F) are presented. 13 C and 15 N NMR experiments carried out on these and related systems validate sample purity, but also serve as indirect probes of the formation of a halogen bond in the co‐crystal complexes in the solid state. Long‐range changes in the electronic environment, which manifest through changes in the electric field gradient (EFG) tensor, are quantitatively measured using 14 N NMR spectroscopy, with a systematic decrease in the 14 N quadrupolar coupling constant ( C Q ) observed upon halogen bond formation. Attempts at 127 I solid‐state NMR spectroscopy experiments are presented and variable‐temperature 19 F NMR experiments are used to distinguish between dynamic and static disorder in selected product materials, which could not be conclusively established using solely XRD. Quantum chemical calculations using the gauge‐including projector augmented‐wave (GIPAW) or relativistic zeroth‐order regular approximation (ZORA) density functional theory (DFT) approaches complement the experimental NMR measurements and provide theoretical corroboration for the changes in NMR parameters observed upon the formation of a halogen bond.