CRYSTAL STRUCTURE OF 3-[2(4-CHLOROPHENYL) SULFONYL ETHENYL]-6-METHOXY 4H-1-BENZOPYRAN 4-ONE. K. V Narayana Raju, M. Krishnaiah, Department of Physics, Sri Venkateswara University, Tirupati-517 502, India, S. N. Rao, I. Liang Lu, Yu Sheng Chen, Department of Physics, University of Central Oklahoma, Edmond, Oklahoma, USA

The structure of the title compound has been determined as a part of a series for studying the stereochemistry of sulfones which are well known for their clinical and commericial applications. Sulfones are used as fuel additives, plasticisers and anti-icing additives. The fungicidal activity is found to vary depending upon the substance present and its stereo chemical configuration. A high degree of thermodynical stability is associated with sulfone group and also basic properties as a proton acceptor. Sulfur with unsual and diverse properties, as constituent of a variety of inorganic, organic and biological molecules plays an important role for electron transport and associated with its exceptional versatility in bonding which is still debate with participation of 3d orbitals which more plausible when eletronegative groups are involved.

Crystals obtained from methanol are colourless, monoclinic, C2/c with a=39.053(13), b=6.700(2), c=13.471(5)Å, [[beta]]=106.62(3)deg., v=3378(2)Å3, z=8, [[rho]]_c=1.486Mg/cm³, [[lambda]]=0.71073Å, u(MoK[[alpha]])= 0.376mm^-1, F(000)=1560. The structure has been solved by direct methods using MULTAN 80 with 2685 reflections collected on syntex P3 diffractometer. Refinement by full matrix least-square method using XRAY 80 converged at R=0.0687 Rw=0.1621 and s=0.88 for 2166 significant reflections.

The molecule contain three nealy planar segments ie benzopyranone, the chlorophenyl ring and ethylene group. The fragment C-C-C-S-C is slightly non planar and is inclined at 60deg. to the planar benzopyran ring and at 106.17deg. to the plane of the chlorophenyl group. The molecular geometry will be discussed.