C-13-Sn-119 correlation NMR in solution and solid-state CP/MAS NMR of bis(tributylstannyl(IV)) O-5,6-isopropylidene-L-(+)-ascorbate

Various NMR correlation techniques, H-1-C-13 HMQC, H-1-C-13 HMBC, H-1-Sn-11 9 HMQC with gradient enhancement, and C-13-Sn-119 HMQC, enabled a. full res onance assignment and the solution structure elucidation of bis(tributylsta nnyl(IV)) L-(+)-ascorbate (1) and O-5,6-isopropylidene-L-(+)-ascorbate (2) in deuteriochloroform. Double heteronuclear C-13-Sn-119 HMQC spectroscopy a ppeared indispensable for discriminating between (2)J(C-13-O-Sn-119) and (3 )J(C-13=C-O-Sn-119) coupling pathways involving quaternary carbon atoms and provided useful information about the relative magnitudes of (2)J(C-13-Sn- 119) and (3)J(C-13-Sn-119) coupling constants, as they turned out to have a n uncommon coupling size sequence. While the tin atoms in compounds I and 2 are four-coordinate in solution, Sn-117 CP/MAS NMR reveals that compound 2 has one four-coordinate and one five-coordinate tin atom in the solid stat e.