STRUCTURE AND CONFORMATION OF TWO NEW DIAZABICYCLO [5.3.0] DECAN-2-ONES. D.kumaran, M.N.Ponnuswamy and G.Shanmugam, Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Madras - 600 025, India, K.Sivakumar and Hoong-Kun Fun, X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.

Several azabicyclo nonanes have been studied widely to find out various conformational possibilities and intramolecular interactions. On treating 2,4-diphenyl-3-azabicyclo [3.3.1] nonane, with sodium azide in the presence of sulfuric acid, new types of rearranged products, diazabicyclo [5.3.0] decan-2-ones compounds are obtained.

The structure of two compounds are determined. Both the crystals belong to the monoclini space group P21/c with Z=4.

Compound I : a = 14.462(1), b = 9.568(1)

c = 14.479(1), beta = 118.46(1)

V = 1765.1(3)

Compound II : a = 9.378(1), b = 8.791(1)

c = 26.306(2), beta = 97.22(1)

V = 2151.5(4)

In both the molecules the fused seven and five membered rings adopt chair-envelope conformation. The molecules are stabilized by Vander Waals forces of interaction. Further details will be discussed in detail.