STRUCTURE OF 19-METHYLSTRYCHNINIUM (S)-(S-[(R)-1,2-DI(ETHOXYCARBONYL)ETHYL] O-METHYL PHOSPHORODITHIOATE)

C22H25N2O2+.C9H16O6PS2-, M(r) = 664.77, monoclinic, P2(1), a = 8.3925 (14), b = 8.0054 (14), c = 24.3050 (42) angstrom, beta = 98.518 (6)-degrees, V = 1614.9 (6) angstrom3, Z = 2, D(m) = 1.42 (3), D(x) = 1.37 g CM-3, lambda(Mo Kalpha) = 0.7107 angstrom (Zr filter, no monochromator), mu = 2.2 cm-1, F(000) = 704, T = 294 (2) K, R = 0.049 and wR = 0.046 for 2417 unique observed reflections. The crystal structure consists of sheets of N-methylstrychninium cations in a bilayer, which alternate with sheets of phosphorodithioate anions, also in a bilayer. The anion is a dealkylated precursor to a specific stereoisomer of isomalathion, and its two chiral centers are identified as S at the P atom and R at the C atom.