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 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 characterized via single crystal and powder X-ray diffraction and Raman spectroscopy.

以1,8-萘二甲酸酐(1,8-naphthalic anhydride)分别与消旋3-氨基奎宁环烷、手性(S)或(R)-(-)-3-氨基奎宁环烷发生缩合反应，可制备三种新型消旋及对映纯氮供体配体(aza-donor ligand)，分别为NMiABCO(1)、(S)-NMiABCO(2a)与(R)-NMiABCO(2b)。消旋体NMiABCO(1)结晶于单斜晶系空间群P2₁/c，Z′=1；而对映纯的(S)-NMiABCO(2a)与(R)-NMiABCO(2b)则结晶于手性单斜晶系空间群P2₁，Z′=2，二者均表现出显著的假中心对称性，且与消旋体NMiABCO(1)呈假同晶型。本研究还探究了消旋及对映纯NMiABCO分别与碘单质、卤素互化物IBr的反应性，以消除假同晶现象，最终得到三种新型分子加合物[NMiABCO·I₂](3)、[(S)-NMiABCO·I₂]·xCHCl₃(4)、[(S)-NMiABCO·IBr]·xCHCl₃(5)以及一种分子盐[HNMiABCO][IBr₂](6)。配合物3与4的合成还可通过固相揉合与气相熏蒸法完成。所有化合物均通过单晶X射线衍射、粉末X射线衍射以及拉曼光谱进行了全面表征。