Intriguing Case of Pseudo-Isomorphism between Chiral and Racemic Crystals of rac- and (S)/(R)2-(1,8-Naphthalimido)-2-quinuclidin-3-yl, and Their Reactivity Toward I2 and IBr

Abstract

Condensation reactions between 1,8-naphthalic anhydride and racemic 3-aminoquinuclidine or chiral (S) or (R)-(−)-3-aminoquinuclidine allowed preparation of three novel racemic and enantiopure aza-donor ligands, namely NMiABCO (1), (S)NMiABCO (2a), and (R)NMiABCO (2b). Racemic NMiABCO (1) crystallizes in the monoclinic space group P21/c, Z′ = 1, while enantiopure (S)NMiABCO (2a) and (R)NMiABCO (2b) crystallize in the chiral monoclinic space group P21, Z′ = 2, and show significant pseudocentrosymmetry, being pseudo-isomorphous with racemic NMiABCO (1). Reactivity of both racemic and enantiopure NMiABCO toward iodine and interhalogen IBr was also investigated as a way to remove the pseudoisomorphism, yielding the three new molecular adducts [NMiABCO·I2] (3), [(S)NMiABCO·I2]·xCHCl3 (4), [(S)NMiABCO·IBr]·xCHCl3 (5) and the molecular salt [HNMiABCO][IBr2] (6). Synthesis of complexes 3 and 4 was also carried out in the solid state via kneading and vapor digestion techniques. All compounds were fully characterize...