13C and 19F solid‐state NMR and X‐ray crystallographic study of halogen‐bonded frameworks featuring nitrogen‐containing heterocycles. Issue 3 (6th February 2017)

• Record Type: Journal Article
• Authors: Szell, Patrick M. J.; Gabriel, Shaina A.; Gill, Russell D. D.; Wan, Shirley Y. H.; Gabidullin, Bulat; Bryce, David L.
• Is Part Of: Acta crystallographica. Volume 73:Issue 3(2017)
• Page Start: 157
• Page End: 167
• Publication Date: 2017-02-06
• Subjects: NMR crystallography -- SSNMR -- halogen‐bonded frameworks -- crystal structure -- nitrogen‐containing heterocycles -- crystal engineering -- DFT calculations; Crystallography -- Periodicals; Crystals -- Periodicals; 548.3
• DOI: 10.1107/S2053229616015023
• Languages: English
• ISSNs: 2053-2296

Abstract

Abstract : A crystallographic and structural analysis of halogen‐bonded compounds by applying a combined X‐ray diffraction (XRD) and solid‐state nuclear magnetic resonance (SSNMR) approach is reported. 13 C and 19 F solid‐state magic‐angle spinning (MAS) NMR is shown to be a convenient method to characterize the structural features of the halogen‐bond donor and acceptor, with chemical shifts attributable to cocrystal formation observed in the spectra of both nuclides. Abstract : Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ‐hole) and an electron donor. We report a crystallographic and structural analysis of halogen‐bonded compounds by applying a combined X‐ray diffraction (XRD) and solid‐state nuclear magnetic resonance (SSNMR) approach. Single‐crystal XRD was first used to characterize the halogen‐bonded cocrystals formed between two fluorinated halogen‐bond donors (1, 4‐diiodotetrafluorobenzene and 1, 3, 5‐trifluoro‐2, 4, 6‐triiodobenzene) and several nitrogen‐containing heterocycles (acridine, 1, 10‐phenanthroline, 2, 3, 5, 6‐tetramethylpyrazine, and hexamethylenetetramine). New structures are reported for the following three cocrystals, all in the P 21 / c space group: acridine–1, 3, 5‐trifluoro‐2, 4, 6‐triiodobenzene (1/1), C6 F3 I3 ·C13 H9 N, 1, 10‐phenanthroline–1, 3, 5‐trifluoro‐2, 4, 6‐triiodobenzene (1/1), C6 F3 I3 ·C12 H8 N2, and 2, 3, 5, 6‐tetramethylpyrazine–1, 3, 5‐trifluoro‐2, 4, 6‐triiodobenzene (1/1), C6 F3 I3 ·C8 H12 N2 . 13 C and 19 F solid‐state magic‐angle spinning (MAS) NMR is shown to be a convenient method to characterize the structural features of the halogen‐bond donor and acceptor, with chemical shifts attributable to cocrystal formation observed in the spectra of both nuclides. Cross polarization (CP) from 19 F to 13 C results in improved spectral sensitivity in characterizing the perfluorinated halogen‐bond donor when compared to conventional 1 H CP. Gauge‐including projector‐augmented wave density functional theory (GIPAW DFT) calculations of magnetic shielding constants, along with optimization of the XRD structures, provide a final set of structures in best agreement with the experimental 13 C and 19 F chemical shifts. Data for carbons bonded to iodine remain outliers due to well‐known relativistic effects.