title: Molecular and electron-spin structures of a ring-shaped mixed-valence polyoxovanadate (IV, V) studied by (11)B and (23)Na solid-state NMR spectroscopy and DFT calculations.
abstract: (11)B and (23)Na solid-state nuclear magnetic resonance (NMR) spectra of ring-shaped paramagnetic crystals of H15[V7(IV)V5(V)B32O84Na4]·13H2O containing seven d(1) electrons from V(IV) were studied. Magic-angle-spinning (MAS) and multiple-quantum MAS NMR experiments were performed at moderate (9.4T) and ultrahigh magnetic fields (21.6T). The NMR parameters for quadrupole and isotropic chemical shift interactions were estimated by simulation of the NMR spectra and from relativistic density functional theory (DFT) calculations. Four Na ions incorporated into the framework were found to occupy four distinct sites with different populations. The DFT calculation showed that d(1) electrons with effectively one up-spin caused by strong antiferromagnetic interactions were delocalized over the 12V ions.
authors.affiliation: Institute of Arts and Sciences, Yamagata University, Yamagata 990-8560, Japan. Electronic address: iijima@kdw.kj.yamagata-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Iijima
authors.affiliation: Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8503, Japan; MO Device Corporation, Kanazawa 920-0335, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yamase
authors.affiliation: Institute for Molecular Science, Okazaki 444-8585, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nishimura
keywords: Antiferromagnetic; MQMAS; Open shell; POM; Paramagnetic; Quadrupole