A1 Refereed original research article in a scientific journal
Metal-Bound Nitrate Anion as an Acceptor for Halogen Bonds in Mono-Halopyridine-Copper(II) Nitrate Complexes
Authors: Puttreddy R., Peuronen A., Lahtinen M., Rissanen K.
Publisher: AMER CHEMICAL SOC
Publication year: 2019
Journal: Crystal Growth and Design
Journal name in source: CRYSTAL GROWTH & DESIGN
Journal acronym: CRYST GROWTH DES
Volume: 19
Issue: 7
First page : 3815
Last page: 3824
Number of pages: 10
ISSN: 1528-7483
eISSN: 1528-7505
DOI: https://doi.org/10.1021/acs.cgd.9b00284
Abstract
Fifteen n-halopyridine-Cu(NO3)(2) complexes (n = 2, 3, 4) obtained from two different solvents, acetonitrile and ethanol, are investigated for C-X center dot center dot center dot O-N halogen bonds (XBs) in the solid state by single and powder X-ray diffraction. The nitrate anions bind copper(II) via anisobidentate modes and one of three oxygens act as an XB acceptor to halogens on the core pyridine rings. The N-metal coordination activates the electron-deficient pi-system and triggers even C2- and C4-chlorines in the corresponding [Cu(2-chloropyridine)(2)(NO3)(2)] and [Cu(4-chloropyridine)(2)(NO3)(2)(ACN)] complexes to form short C-Cl-2/Cl4 center dot center dot center dot O-N halogen bonds. Notably, the C2-Cl2 center dot center dot center dot O-N XBs with a normalized XB distance parameter (R-XB) of 0.89 is close to C2-I2 center dot center dot center dot O-N XBs [R-XB = 0.88] in the [Cu(2-iodopyridine)(2)(NO3)(2)] complex. In overall, the C-X center dot center dot center dot O-N halogen bonds in the studied complexes range from moderately short to roughly the van der Waals contact distance of the respective X center dot center dot center dot O atoms (R-XB = 0.88-0.99) and have a varying significance in governing the molecular packing respective of the complex. Among the studied complexes, two main coordination modes were observed distorted octahedral and distorted pentagonal bipyramid-of which the latter results from the coordination of acetonitrile to the Cu(II) ion. The crystal structures showed that the steric bulk of C2-halogens in 2-halopyridines prevent this, while in similar conditions the 3- and 4-halopyridine ligands yield acetonitrile bound Cu(II)-complexes.
Fifteen n-halopyridine-Cu(NO3)(2) complexes (n = 2, 3, 4) obtained from two different solvents, acetonitrile and ethanol, are investigated for C-X center dot center dot center dot O-N halogen bonds (XBs) in the solid state by single and powder X-ray diffraction. The nitrate anions bind copper(II) via anisobidentate modes and one of three oxygens act as an XB acceptor to halogens on the core pyridine rings. The N-metal coordination activates the electron-deficient pi-system and triggers even C2- and C4-chlorines in the corresponding [Cu(2-chloropyridine)(2)(NO3)(2)] and [Cu(4-chloropyridine)(2)(NO3)(2)(ACN)] complexes to form short C-Cl-2/Cl4 center dot center dot center dot O-N halogen bonds. Notably, the C2-Cl2 center dot center dot center dot O-N XBs with a normalized XB distance parameter (R-XB) of 0.89 is close to C2-I2 center dot center dot center dot O-N XBs [R-XB = 0.88] in the [Cu(2-iodopyridine)(2)(NO3)(2)] complex. In overall, the C-X center dot center dot center dot O-N halogen bonds in the studied complexes range from moderately short to roughly the van der Waals contact distance of the respective X center dot center dot center dot O atoms (R-XB = 0.88-0.99) and have a varying significance in governing the molecular packing respective of the complex. Among the studied complexes, two main coordination modes were observed distorted octahedral and distorted pentagonal bipyramid-of which the latter results from the coordination of acetonitrile to the Cu(II) ion. The crystal structures showed that the steric bulk of C2-halogens in 2-halopyridines prevent this, while in similar conditions the 3- and 4-halopyridine ligands yield acetonitrile bound Cu(II)-complexes.
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