The cover artwork, designed by Dr. Abril Castro, illustrates a nickel-fluoride complex involved in halogen bonding and exposed to a magnetic field symbolized by the Northern Lights. The open-access article, Solid-state 19F NMR chemical shift in square-planar nickel-fluoride complexes linked by halogen bonds, is the result of a collaboration with Prof. Robin N. Perutz from the University of York and Dr. Christophe Raynaud from the University of Montpellier.
The study sheds light on the impact of halogen bonds on the NMR signatures. The researchers employed a computational protocol for modelling and analyzing the 19F SSNMR chemical shifts previously measured in a family of square-planar trans NiII-L2-iodoaryl-fluoride (L = PEt3) complexes capable of forming self-complementary networks held by a NiFI(C) halogen bond (Chem. Sci. 2018, 9, 3767).
By performing 19F NMR chemical shift calculations, the researchers found that the observed difference in chemical shift between solid-state and solution NMR can be essentially attributed to the XB interaction. The analysis of the factors controlling the shielding shows that the deshielding of the fluoride in the halogen-bonded systems is attributed to an increase in the energy gap between the occupied and vacant orbitals that are mostly responsible for the paramagnetic terms, notably along the most shielded direction.