Azabicyclo[3.3.1]nonanone: a case when weak interactions are preferred over strong hydrogen bonds

Derivatives of azabicyclo[3.3.1]nonanone tend to prefer for weak interactions in the crystal over strong N-H center dot center dot center dot O hydrogen bonds. The main stabilizing forces in the investigated azatricyclo[7.3.1.0(2,7)]trideca-trienone derivatives are C-H center dot center dot center dot O, N-H center dot center dot center dot pi and C-H center dot center dot center dot pi interactions, leading to interesting structural patterns. The azabicyclo[3.3.1]nonanone ring adopts chair-envelope conformation having exo-C2,C4-aromatic substituents. Amino NH is in trigonal pyramidal configuration. The interesting stereochemistry of azabicyclo[3.3.1]nonanone, driving exceptional preference for weaker interactions over strong hydrogen bonds serves a useful example toward engineering and design strategy, and structure prediction methodologies.