Hyperfine interactions between unpaired electrons and framework atoms in aluminosilicate sodalites containing paramagnetic Na43+ clusters: a 29Si and 27Al MAS NMR study

Abstract

First NMR evidence is presented for hyperfine interactions between unpaired electrons and the framework atoms in alkali-metal doped zeolites by the ²⁷Al and ²⁹Si MAS NMR spectra of aluminosilicate sodalites loaded with paramagnetic Na₄³⁺ cluster which show up to seven resonances with characteristic down-field shifts caused by Fermi contact interactions between the unpaired electrons of sodium clusters and the Al and Si atoms of the sodalite framework.