HYPERFINE INTERACTIONS BETWEEN UNPAIRED ELECTRONS AND FRAMEWORK ATOMSIN ALUMINOSILICATE SODALITES CONTAINING PARAMAGNETIC NA-4(3- A SI-29 AND AL-27 MAS NMR-STUDY() CLUSTERS )

First NMR evidence is presented for hyperfine interactions between unp aired electrons and the framework atoms in alkali-metal doped zeolites by the Al-27 and Si-29 MAS NMR spectra of aluminosilicate sodalites l oaded with paramagnetic Na-4(3+) clusters which show up to seven reson ances with characteristic down-field shifts caused by Fermi contact in teractions between the unpaired electrons of the sodium clusters and t he Al and Si atoms of the sodalite framework.