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Comparing the Halogen Bond to the Hydrogen Bond by Solid‐State NMR Spectroscopy: Anion Coordinated Dimers from 2‐ and 3‐Iodoethynylpyridine Salts
Author(s) -
Szell Patrick M. J.,
Cavallo Gabriella,
Terraneo Giancarlo,
Metrangolo Pierangelo,
Gabidullin Bulat,
Bryce David L.
Publication year - 2018
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.201801279
Subject(s) - halogen bond , halogen , isostructural , hydrogen bond , chemistry , crystallography , halide , solid state nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , chemical shift , crystal structure , molecule , inorganic chemistry , stereochemistry , organic chemistry , nuclear magnetic resonance , alkyl , physics
Halogen bonding is an increasingly important tool in crystal engineering, and measuring its influence on the local chemical and electronic environment is necessary to fully understand this interaction. Here, we present a systematic crystallographic and solid‐state NMR study of self‐complementary halogen‐bonded frameworks built from the halide salts (HCl, HBr, HI, HI 3 ) of 2‐iodoethynylpyridine and 3‐iodoethynylpyridine. A series of single crystal X‐ray structures reveals the formation of discrete charged dimers in the solid state, directed by simultaneous X − ⋅⋅⋅H−N + hydrogen bonds and C−I⋅⋅⋅X − halogen bonds (X=Cl, Br, I). Each compound was studied using multinuclear solid‐state magnetic resonance spectroscopy, observing 1 H to investigate the hydrogen bonds and 13 C, 35 Cl, and 79/81 Br to investigate the halogen bonds. A natural localized molecular orbital analysis was employed to help interpret the experimental results. 1 H SSNMR spectroscopy reveals a decrease in the chemical shift of the proton participating in the hydrogen bond as the halogen increases in size, whereas the 13 C SSNMR reveals an increased 13 C chemical shift of the C−I carbon for C−I⋅⋅⋅X − relative to C−I⋅⋅⋅N halogen bonds. Additionally, 35 Cl and 79/81 Br SSNMR, along with computational results, have allowed us to compare the C−I⋅⋅⋅X − halogen bond involving each halide in terms of NMR observables. Due to the isostructural nature of these compounds, they are ideal cases for experimentally assessing the impact of different halogen bond acceptors on the solid‐state NMR response.