On the assignment of 119Sn resonances of bis[dicarboxylatotetraorganodistannoxanes] in solution and solid state 119Sn NMR spectra

Abstract

The scope and limitations of 119Sn resonance assignment strategies for structural characterizations of bis[dicarboxylatotetraorganodistannoxanes] by 2D gradient assisted 1H– 119Sn HMQC NMR in solution and MAS 119Sn NMR in the solid state are discussed for three compounds, the structure of which was already known by X-ray diffraction, bis[diacetatotetramethyldistannoxane] ( 1), bis[bis(2,2-dimethylpropanoato)tetramethyldistannoxane] ( 3), bis[bis(pentafluorobenzoato)tetra- n-butyldistannoxane] ( 4) and for the novel compound bis[bis(4-methylbenzoato)tetramethyldistannoxane] ( 2), for which an X-ray crystal structure is also reported. The structures of {R′COO(R 2Sn)–O–(SnR 2)OOCR′} 2 each feature a central R 8Sn 4O 2 core, and in addition to the μ 3-oxo links between the endo- and exo-cyclic tin atoms, the carboxylate ligands associating in a variety of structural motifs. Their relationship to 119Sn MAS NMR patterns, in particular, the principal components of the 119Sn shielding tensors, is discussed.