title: How Ions Arrange in Solution: Detailed Insight from NMR Spectroscopy of Paramagnetic Ion Pairs.
abstract: 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 of1H,13C,14N, and31P 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.
authors: Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany), Tel: +49-6221-54-6247, Fax: +49-6221-54-161-6247.
authors: Marko
authors: M
authors: Damjanović
authors: Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai, 980-8578, Japan.
authors: Takaumi
authors: T
authors: Morita
authors: Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai, 980-8578, Japan.
authors: Yoji
authors: Y
authors: Horii
authors: Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai, 980-8578, Japan.
authors: Keiichi
authors: K
authors: Katoh
authors: Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai, 980-8578, Japan.
authors: Masahiro
authors: M
authors: Yamashita
authors: Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany), Tel: +49-6221-54-6247, Fax: +49-6221-54-161-6247.
authors: Markus
authors: M
authors: Enders
keywords: NMR spectroscopy; ion pairs; magnetic anisotropy; magnetic properties; pseudo-contact shifts