Halogen Bonds in Square Planar 2,5‐Dihalopyridine‐Copper(II) Bromide Complexes
Puttreddy, R., von Essen, C., & Rissanen, K. (2018). Halogen Bonds in Square Planar 2,5‐Dihalopyridine‐Copper(II) Bromide Complexes. European Journal of Inorganic Chemistry, 2018 (20-21), 2393-2398. doi:10.1002/ejic.201800144
Julkaistu sarjassaEuropean Journal of Inorganic Chemistry
Embargo päättyy: 2019-03-25Pyydä artikkeli tutkijalta
© 2018 Wiley-VCH Verlag GmbH & Co.
Halogen bonding in self‐complementary 1:2 metal–ligand complexes obtained from copper(II) bromide (CuBr2) and seven 2,5‐dihalopyridines were analyzed using single‐crystal X‐ray diffraction. All presented discrete complexes form 1D polymeric chains connected with C–X···Br–Cu halogen bonds (XB). In (2‐chloro‐5‐X‐pyridine)2·CuBr2 (X = Cl, Br, and I) only the C5‐halogen and in (2‐bromo‐5‐X‐pyridine)2·CuBr2 (X = Cl, Br, and I) both C2‐ and C5‐halogens form C–X···Br–Cu halogen bonds with the X acting as the XB donor and copper‐coordinated bromide as the XB acceptor. The electron‐withdrawing C2‐chloride in (2‐chloro‐5‐X‐pyridine)2·CuBr2 complexes has only a minor effect on the C5–X5···Br–Cu XBs, and the X5···Br distances follow the expected order I5 < Br5 < Cl5 with RXB values of 0.91, 0.94, and 0.99, respectively. In (2‐bromo‐5‐X‐pyridine)2·CuBr2 complexes, due to the polarization of both halogens, the C2–X2···Br–Cu and C5–X5···Br–Cu RXB values are very similar [0.92–0.99] as a result of the competition between C2‐ and C5‐halogens for XB formation. In addition to the classical halogen bonds, the square‐planar CuII complexes exhibit C2–X2···Cu (X = Cl and Br) contacts perpendicular to the Br–Cu–Br plane with shorter C2–Br2···Cu than C2–Cl2···Cu contacts. These interactions induce a pseudo‐octahedral geometry for CuII ions. Notably, C2–X2···Br–Cu halogen bonds and the additional C2–X2···Cu contacts are slightly enhanced by the C5‐halogen electronegativity. ...