CTQ BULLETIN OF MAGNETIC RESONANCE The Quarterly Review Journal of the International Society of Magnetic Resonance Editor:

A wide range of novel supramolecular (three-dimensional) heterometallic compounds, synthesized at the University of Hamburg, have been studied by magic-angle spinning NMR using 1 C, N, Sn and 2 0 7 Pb nuclei. Typical examples are [(Me3Sn)3Co(CN)<5]oo and [(Me3Sn)4Fe(CN)6Joo. The systems are insoluble and often not in forms suitable for single-crystal Xray work. The NMR results are therefore vital in establishing the chemical structures. Crystallographic asymmetric units have been determined and compared to diffraction results, where known, but there are some discrepancies. The metal chemical shifts indicate the coordination nature of tin and lead. Spinning sideband analyses yield data on shielding tensor components. The cyanide C and (in some cases) Sn signals indicate the presence of second-order quadrupolar effects from residual dipolar coupling to N. The N spectra, usually obtained using natural isotopic abundance, clarify the number of cyanide environments. Compounds of the type [(Me3Sn)4M(CN)6J0O show cation exchange properties for one of the Me3Sn groups but NMR indicates two Sn signals of equal intensity. The reasons for this anomaly are discussed. The methyl signals for these systems are broad at room temperature. Low temperature spectra show there is an exchange process occurring, presumably internal rotation of the -SnMe3group (methyls equatorial). Details of this process are confirmed by two-dimensional NMR studies. *Paper presented at the Xlth ISMAR Symposium. Vancouver. July 1992. Author to whom correspondence should be addressed.