METHYL CARBONYLBENZOYL)-TRIPHENYLPHOSPHORANYLIDENEACETATE AND ITS ETHANOLATE COMPLEX

Two different crystals of the compound methyl carbonylbenzoyl)tripheny lphosphoranylideneacetate, C30H25O5P (I) and C30H25O5P.0.5C2H6O (II), were studied by X-ray diffraction. The second crystal contains a molec ule of ethanol close to an inversion centre. The solvent molecule is d isordered on two positions and is involved in hydrogen bonding with th e O atom of a carbonyl group. In crystal (1), he P-C(phenyl) distances vary from 1.808 (6) to 1.819 (5) angstrom while the fourth P-C bond i s shorter, at 1.759 (4) angstrom. In crystal (II), the P-C(phenyl) dis tances are 1.811 (6)-1.817 (6) angstrom and the fourth P-C bond is als o shorter, at 1.763 (6) angstrom. These values suggest a multiple natu re for the P-C bond. A high-field methoxy signal observed in the NMR s pectrum was attributed to the shielding magnetic anisotropic effect of the phenyl rings of the PPh3 group.