The crystallographically observed molecular structure of the title compound, C19H17NO, and its inverted counterpart are compared with that calculated by density functional theory (DFT) at the B3LYP/6-311++G(d, p) level. The results from both methods suggest that the observed molecular conformation of the title compound is primarily determined by intermolecular interactions in the crystal structure. The periodic organization of the molecules is stabilized by weak C - H center dot center dot center dot O and C - H center dot center dot center dot pi hydrogen bonds and thus a two-dimensional puckered network consisting of R-4(4)(22) and R-4(4)(38) ring motifs is established. The title molecule has a (+)-antiperiplanar conformation about the C - C bond in the aminoacetone bridge. The pyramidal geometry observed around the vertex N atom is flattened by the presence of bulky phenyl and naphthylethanone fragments.