Solid‐state 119Sn NMR and antitumor activity of bis [1,3‐bis (3‐oxapentamethylenecarbamoylthioacetato)‐1,1,3,3‐tetrabutyl‐1,3‐distannoxare], and the crystal structure of its bis‐ethanol solvate

The ¹¹⁹Sn cross polarization‐magic angle spinning NMR spectrum of bis1,3‐bis(3‐oxapentamethylenecarbamoylthioacetato)‐1,1,3,3‐tetrabutyl‐1,3‐distannoxane], {(C₄H₉)₂SnO₂CCH₂SC(O)N(CH₂CH₂)₂O]₂O}₂, which consists of two resonances of similar chemical shifts and symmetry (δ_iso = −152, −202 ppm; asymmetry, κ = 0.38), implies the existence of two five‐coordinate tin sites in the centrosymmetric dimer. The assignment has been corroborated by X‐ray diffraction analysis on the compound that has been crystallized from ethanol; the crystal structure shows two tin atoms in cis‐C₂SnO₃ trigonal‐bipyramidal coordination C‐Sn‐C = 131.5(1), 131.3(2) °]. The analysis also reveals the presence of two lattice ethanol molecules that are hydrogen‐bonded to the dimer OO = 2.779(5) Å]. When exposed to air, the distannoxane loses ethanol. The unsolvated distannoxane is more active than cis‐platin when screened against MCF‐7 (mammary cancer), EVSA‐T (mammary cancer), WiDr (colon cancer), IGROV (ovarian cancer), M19 MEL (melanoma), A498 (renal cancer) and H226 (lung cancer) cell lines. Copyright © 2000 John Wiley & Sons, Ltd.