a Bayerisches Geoinstitut, Universität Bayreuth, 95440, Bayreuth, Germany
b Karl-Franzens-Universität Graz, Institut für Chemie, Anorganische Chemie, Schubertstrasse 1, A-8010, Graz, Austria
Abstract:
We consider 29Si and 19F MAS NMR spectra of isolated 29Si(19F)2 and 29Si(19F)3 spin systems in two organosilicon compounds of the type RR’SiF2 and RSiF3(R,R′=organic ligands). Experimental spectra are analysed by means of numerical simulations. It is found that the SiF3 group in RSiF3 is reorienting rapidly around the molecular Si–C bond direction in the solid state. The two 19F shielding tensors in RR’SiF2 have strongly differing orientations relative to the two Si–F bond directions in the molecule. Possibilities and limitations of straightforward MAS NMR approaches for the full characterisation of 29Si(19F)2 and 29Si(19F)3 spin systems and other dipolar coupled two and three-spin systems are discussed.