The molecular and crystal structures of C(C6H5)4, Si(C6H5)4, Sn(C6Hs)4 and Pb(C6Hs)4 have been determined by conformational analyses and lattice energy calculations. The molecular conformations and crystal structures correspond to the potential energy minima• The structure of Sn(C6Hs)4 is in good agreement with that determined experimentally by the X-ray method•

These data indicate that B. spectabilis flowers extracts exert protective effect against the toxic effects of rotenone on brain, liver and kidney. B. spectabilis flowers extracts decreased brain lipid peroxidation and prevented neuronal death due to rotenone and might thus prove the value in treatment of Parkinson's disease.

Crystals ofp-diethynylbenzene, Cx0H6, are monoclinic with a = 4.007, b = 6.018, c = 15.340/~,,/3 = 91 ° 42'.The space group is P21/c with two centrosymmetric molecules in the unit cell. The structure was determined from three-dimensional Patterson maps with the aid of the calculation of molecular packing using the method of atom-atom potentials. The C=C bond length is 1.188 A, with the carbon atoms lying approximately in the plane of the benzene ring. The experimental and theoretical structures are in good agreement.

3,6-Diphenyl-s-tetrazine forms monoclinic crystals with a= 5-415, b= 5.183, c= 20"603 A, fl = 101030 '.There are two molecules in the unit cell in the space group P21/e. The structure was determined experimentally by X-ray three-dimensional analysis. The molecule is centrosymmetrical and planar. Theoretical calculation of the packing position of the molecule was carried out using the atom-atom potentials method. The orientation of the molecule in the unit cell is in agreement with that determined experimentally. The molecule is exactly or approximately planar.

No abstract