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

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 P2(1)/c, Z' = 1, while enantiopure (S)NMiABCO (2a) and (R)NMiABCO (2b) crystallize in the chiral monoclinic space group P2(1), 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 center dot I-2] (3), [(S)NMiABCO center dot I-2]center dot xCHCl(3) (4), [(S)NMiABCO center dot IBr]center dot xCHCl(3) (5) and the molecular salt [HNMIABCO][1Br(2)] (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 characterized via single crystal and powder X-ray diffraction and Raman spectroscopy.