3-Nitroso-2,4,6,8-tetra-phenyl-3,7-diaza-bicyclo-[3.3.1]nonan-9-one.

In the title compound, C(31)H(27)N(3)O(2), the two piperidine rings fused to each other each adopt a slightly distorted chair conformation. The phenyl rings on the N-unsubstituted piperidine ring occupy an equatorial position, while those on the N-nitroso-substituted piperidine ring are in axial positions. The NO group is approximately coplanar with the piperidine ring with a maximum deviation of 0.048 (4) Å. The dihedral angles between the mean planes of the axially and equatorially oriented phenyl rings are 27.7 (1) and 31.9 (1)°, respectively. Mol-ecular packing is stabilized by weak inter-molecular C-H⋯O and C-H⋯π inter-actions.