Dichlorine-pyridine N-oxide halogen-bonded complexes
N. Limberg, J. M. Rautiainen, J. Lundell, S. Riedel, K. Rissanen, R. Puttreddy – 2024
A new Cl-Cl...(-)O-N(+) halogen-bonded paradigm has been demonstrated, using dichlorine as a halogen bond (XB) donor and N-oxide as an XB acceptor. Their crystalline complexes were formed during the warm-up process from -196 degrees C to -80 degrees C for X-ray diffraction analysis. They exhibit high instability in the crystalline state, even at these low temperatures, leading to rapid decomposition and the formation of Clcdots, three dots, centeredH-O-N hydrogen-bonded complexes. The normalized XB interaction ratio (R (XB)) of Clcdots, three dots, centeredO interactions in the solid-state demonstrates affinity comparable to traditional Icdots, three dots, centeredO interactions observed in I-I...(-)O-N(+) halogen-bonded systems. The Cl-Clcdots, three dots, centeredO XB angles vary from 172 degrees to 177 degrees , manifesting the structure-guiding influence of the electronegative chlorine atom's sigma-hole on these XB interactions.
