SYNTHESIS AND CRYSTAL-STRUCTURE OF IODOME THYLTRIPHENYLPHOSPHONIUM IODIDE(C6H5)(3)PCH2I-(I)

Iodomethyltriphenylphosphonium iodide, (C6H5)(3)PCH2I+I-, has been pre pared by the reaction of (C6H5)(3)P with CH2I2 in dichloromethane form ing colourless needle like crystals. The crystal and molecular structu res have been determined by an X-ray structure analysis. The crystals are orthorhombic, space group Pca2(1), Z = 8; a = 1478,8(3) pm, b = 12 49,3(3) pm, c = 2053,2(3) pm. R = 0.050 for 3219 observed reflections with I greater than or equal to 2 sigma the solid state the title comp ound exists as two discrete monomeric units, (C6H5)(3)PCH2I+I-. In bot h symmetry independent units the I-I distances are surprisingly short with 346,5(1) pm and 356,3(1) pm. For the title compound the results o f AM1, PM3, and MNDO calculations are in good agreement with correspon ding values determined by the X-ray analysis.