Strong N−X⋅⋅⋅O−N Halogen Bonds: A Comprehensive Study on N‐Halosaccharin Pyridine N‐Oxide Complexes |
| |
Authors: | Rakesh Puttreddy J Mikko Rautiainen Toni Mkel Kari Rissanen |
| |
Institution: | Rakesh Puttreddy,J. Mikko Rautiainen,Toni Mäkelä,Kari Rissanen |
| |
Abstract: | A study of the strong N?X????O?N+ (X=I, Br) halogen bonding interactions reports 2×27 donor×acceptor complexes of N‐halosaccharins and pyridine N‐oxides (PyNO). DFT calculations were used to investigate the X???O halogen bond (XB) interaction energies in 54 complexes. A simplified computationally fast electrostatic model was developed for predicting the X???O XBs. The XB interaction energies vary from ?47.5 to ?120.3 kJ mol?1; the strongest N?I????O?N+ XBs approaching those of 3‐center‐4‐electron N?I?N]+ halogen‐bonded systems (ca. 160 kJ mol?1). 1H NMR association constants (KXB) determined in CDCl3 and D6]acetone vary from 2.0×100 to >108 m ?1 and correlate well with the calculated donor×acceptor complexation enthalpies found between ?38.4 and ?77.5 kJ mol?1. In X‐ray crystal structures, the N‐iodosaccharin‐PyNO complexes manifest short interaction ratios (RXB) between 0.65–0.67 for the N?I????O?N+ halogen bond. |
| |
Keywords: | Halogenbindungen N-Haloimide N-Oxide Saccharin σ -Loch |
|