title: Paramagnetic Prussian Blue Analogues CsM(II)[M(III)(CN)6]. The Quest for Spin on Cesium Ions by Use of (133)Cs MAS NMR Spectroscopy.
abstract: The (133)Cs magic-angle spinning NMR spectra of the paramagnetic compounds CsM(II)[M(III)(CN)6], M(II) = Ni, Co, Fe, Mn; M(II) = Co, Fe, yield unusually large and temperature-dependent signal shifts (up to -950 ppm relative to CsCl at 298 K). Comparison with the spectra of the diamagnetic analogues CsM[Co(CN)6], M = Zn, Cd, shows that the shifts are largely due to the unpaired electrons. This is ascribed to through-bond transfer of spin to the Cs(+) ions, while the through-space effect of the magnetic moments on the signal shifts is shown to be virtually negligible. The mechanism inducing negative spin at Cs(+) is discussed. The magnitude of the spin density (average: |5.8 × 10(-3)| (a.u.) (-3)) suggests that Cs(+) is involved in magnetic exchange interactions of corresponding Prussian blue derivatives.
authors.affiliation: Department Chemie, Technische Universität München, 85748 Garching, Germany.
authors.forename: Frank H
authors.initials: FH
authors.lastname: Köhler
authors.affiliation: Department Chemie, Technische Universität München, 85748 Garching, Germany.
authors.forename: Oksana
authors.initials: O
authors.lastname: Storcheva