Sheets built from C-H...O and C-H...pi(arene) hydrogen bonds in (2RS,6SR)-N-diphenylacetyl-2,6-diphenylpiperidin-4-one and (2RS,3SR,5RS,6SR)-3,5-dimethyl-N-phenylacetyl-2,6-diphenylpiperidin-4-one.

In (2RS,6SR)-N-diphenylacetyl-2,6-diphenylpiperidin-4-one, C31H27NO2, (I), the piperidinone ring adopts an almost ideal twist-boat conformation, and the molecules are linked into sheets by a combination of one C-H...O hydrogen bond and one C-H...pi(arene) hydrogen bond. (2RS,3SR,5RS,6SR)-3,5-Dimethyl-2,6-diphenyl-N-phenylacetylpiperidin-4-one, C27H27NO2, (II), crystallizes with Z' = 2 in the space group P-1; the piperidinone rings adopt an almost ideal boat conformation in one of the molecules and a conformation between boat and twist-boat in the other. The molecules of (II) are linked into sheets by a combination of five C-H...O hydrogen bonds and one C-H...pi(arene) hydrogen bond.