The biological potential of compounds of the tricyclic dibenzo[b,e]azepine system has resulted in considerable synthetic efforts to develop efficient methods for the synthesis of new derivatives of this kind. (9RS,15RS)-9-Ethyl-11-methyl-9,13b-di­hydro­dibenzo[c,f]thia­zolo[3,2-a]azepin-3(2H)-one, C19H19NOS, (I), crystallizes as a kryptoracemate with Z? = 2 in the space group P21, with one mol­ecule each of the (9R,15R) and (9S,15S) configurations in the asymmetric unit, while (9RS,15RS)-9-ethyl-7,12-dimethyl-9,13b-di­hydro­di­benzo[c,f]thia­zolo[3,2-a]aze­pin-3(2H)-one, C20H21NOS, (II), crystallizes with Z? = 1 in the space group C2/c. Ethyl (13RS)-2-chloro-13-ethyl-4-oxo-8,13-di­hydro-4H-benzo[5,6]azepino[3,2,1-ij]quinoline-5-carboxyl­ate, C22H20ClNO3, (III), exhibits enanti­omeric disorder in the space group Poverline{1} such that the reference site is occupied by the 13R and 13S enanti­omers, with occupancies of 0.900?(6) and 0.100?(6). In each of the two independent mol­ecules in (I), the five-membered ring adopts an envelope conformation, but the corresponding ring in (II) adopts a half-chair conformation, while the six-membered ring in the major form of (III) adopts a twist-boat conformation. The conformation of the seven-membered ring in each of (I), (II) and the major form of (III) approximates to the twist-boat form. The mol­ecules of compound (I) are linked by two C?H...O hydrogen bonds to form two independent anti­parallel C(5) chains, with each type containing only one enanti­omer. These chains are linked into sheets by two C?H...?(arene) hydrogen bonds, in which the two donors are both provided by the (9R,15R) enanti­omer and the two acceptor arene rings form part of a mol­ecule of (9S,15S) configuration, precluding any additional crystallographic symmetry. The mol­ecules of compound (II) are linked by inversion-related C?H...?(arene) hydrogen bonds to form isolated cyclic centrosymmetric dimers. The mol­ecules of compound (III) are linked into cyclic centrosymmetric dimers by C?H...O hydrogen bonds and these dimers are linked into chains by a ??? stacking inter­action. Comparisons are made with some related structures.