Natural Abundance 15N and 13C Solid-State NMR Chemical Shifts: High Sensitivity Probes of the Halogen Bond Geometry
Paolo Cerreia Vioglio,[a] Luca Catalano,[b] Vera Vasylyeva,[b] Carlo Nervi,[a]
Michele R. Chierotti,[a] Giuseppe Resnati,[b] Roberto Gobetto,*[a] and
Pierangelo Metrangolo*[b, c]
Chem. Eur. J. 2016, 22
[a] P. Cerreia Vioglio, Prof. C. Nervi, Prof. M. R. Chierotti, Prof. R. Gobetto
Department of Chemistry and NIS centre, University of Torino
Via P. Giuria 7, 10125 Torino (Italy)
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[b] L. Catalano, Dr. V. Vasylyeva, Prof. G. Resnati, Prof. P. Metrangolo
NFMLab-D.C.M.I.C. “Giulio Natta”, Politecnico di Milano
Via L. Mancinelli 7, 20131 Milano (Italy)
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
[c] Prof. P. Metrangolo
VTT-Technical Research Centre of Finland Biologinkuja 7
02150 Espoo (Finland)
Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a versatile characterization technique that can provide a plethora of information complementary to single crystal X-ray diffraction (SCXRD) analysis. Herein, we present an experimental and computational investigation of the relationship between the geometry of a halogen bond (XB) and the SSNMR chemical shifts of the non-quadrupolar nuclei either directly involved in the interaction (15N) or covalently bonded to the halogen atom (13C). We have prepared two series of X-bonded co-crystals based upon two different dipyridyl modules, and several halobenzenes and diiodoalkanes, as XB-donors. SCXRD structures of three novel co-crystals between 1,2-bis(4-pyridyl)ethane, and 1,4-diiodobenzene, 1,6-diiodododecafluorohexane, and 1,8-diiodohexadecafluorooctane were obtained. For the first time, the change in the 15N SSNMR chemical shifts upon XB formation is shown to experimentally correlate with the normalized distance parameter of the XB. The same overall trend is confirmed by density functional theory (DFT) calculations of the chemical shifts. 13C NQS experiments show a positive, linear correlation between the chemical shifts and the C−I elongation, which is an indirect probe of the strength of the XB. These correlations can be of general utility to estimate the strength of the XB occurring in diverse adducts by using affordable SSNMR analysis.
