Uncommon crystal motif of brucine in its diastereomeric salt with (11-oxo-11H-dibenzo[b,f][1,4]thiazepin-10-yl)-acetic acid: a case of possible crystallization-induced dynamic resolution

The paper reports on the molecular and crystal structure of the diastereomeric salt (4) formed by the (11-oxo-11H-dibenzo[b,f][1,4]thiazepin-10-yl)-acetate (H−12) and the brucinium resolving agent. Experimental evidences suggest that the salt was obtained by a crystallization-induced dynamic resolution of the tricyclic compound 2, which seems to constitute the first example of successful application of this technique to tricycles of this kind. A systematic comparison with already published structural data of compounds containing brucine (molecule/ion) evidences that in 4 the resolving cation assembles in an unusual host framework. A review of the solid state structures containing brucine/brucinium moieties available in the literature provides some simple rules which help to exclude/identify a priori the supramolecular host (brucine molecule/ion) framework.