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How Ions Arrange in Solution: Detailed Insight from NMR Spectroscopy of Paramagnetic Ion Pairs
Author(s) -
Damjanović Marko,
Morita Takaumi,
Horii Yoji,
Katoh Keiichi,
Yamashita Masahiro,
Enders Markus
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600804
Subject(s) - paramagnetism , diamagnetism , chemistry , ion , counterion , nuclear magnetic resonance spectroscopy , spectroscopy , molecule , anisotropy , crystallography , inorganic chemistry , analytical chemistry (journal) , stereochemistry , organic chemistry , magnetic field , physics , quantum mechanics
Ion pairing between the paramagnetic anion [Tb(obPc) 2 ] − (obPc=2,3,9,10,16,17,23,24‐octabutoxyphthalocyaninato), which has a very large magnetic anisotropy, with various diamagnetic counterions [P(Ph) 4 ] + ( 1 a ), [As(Ph) 4 ] + ( 1 b ), bis(triphenylphosphine)iminium ([PPN] + , 1 c ) and tetra‐ n ‐butylammonium ([TBA] + , 1 d ) was studied by means of 1 H, 13 C, 14 N, and 31 P NMR spectroscopy in solution at various temperatures. The influence of the paramagnetic anion on the NMR spectroscopy properties of the diamagnetic cations allowed a detailed insight into the distances and relative orientations of the paired ions. Isotropic tumbling models for the description of the quaternary cations are inaccurate, particularly for [TBA] + with its flexible butyl chains. The effects of temperature and concentration were also assessed. The advantage of this technique is that relatively large distances and the orientation between molecules or ions in solution can be studied.