High resolution ¹H and ¹³C NMR resonance assignments and conformational assignments were carried out for four $t(3)$-benzyl-$r$(2),𝑐(6)-bis(aryl)piperidin-4-ones 1-4 and their four 𝑁-nitroso-$t(3)$-benzyl-$r(2)$,$c(6)$-bis(aryl)piperidin-4-ones 5-8. In addition to conventional 1D NMR methods, 2D shiftcorrelated NMR techniques (¹H-¹H COSY and ¹H-¹³C COSY) were used for signal assignments. At room temperature the $t(3)$-benzyl-$r(2)$,$c(6)$-bis(aryl)piperidin-4-ones 1-4 exist in only one isomeric form whereas their 𝑁-nitroso derivatives 5-8 exist in two isomeric forms. The preferred conformations of both the isomeric forms of nitrosamines were determined by comparison of the spectral data with those of the corresponding parent amines 1-4 and with the aid of substituent parameters. The results indicate the presence of an equilibrium mixture of boat forms B₁ and B₂ for Z isomers of 5-8. For the E isomers of 5-8, boat form B₁ is predicted to be the major conformer. The piperidin-4-ones 1-4 exist in normal chair conformations with equatorial orientations of all the substituents.