The spiroborate anion, namely, 2,3,7,8-tetracarboxamido-1,4,6,9-tetraoxa-5λ4-boraspiro[4.4]nonane, [B(TarNH2)2]−, derived from the diol L-tartramide TarNH2, [CH(O)(CONH2)]2, shows a novel self-assembly into two-dimensional (2D) layer structures in its salts with alkylammonium cations, [NR
4]+ (R = Et, Pr and Bu), and sparteinium, [HSpa]+, in which the cations and anions are segregated. The structures of four such salts are reported, namely, the tetrapropylazanium salt, C12H28N+·C8H12BN4O8
−, the tetraethylazanium salt hydrate, C8H20N+·C8H12BN4O8
−·6.375H2O, the tetrabutylazanium salt as the ethanol monosolvate hemihydrate, C16H36N+·C8H12BN4O8
−·C2H5OH·0.5H2O, and the sparteinium (7-aza-15-azoniatetracyclo[7.7.1.02,7.010,15]heptadecane) salt as the ethanol monosolvate, C15H27N2
+·C8H12BN4O8
−·C2H5OH. The 2D anion layers have preserved intermolecular hydrogen bonding between the amide groups and a typical metric repeat of around 10 × 15 Å. The constraint of matching the interfacial area organizes the cations into quite different solvated arrangements, i.e. the [NEt4] salt is highly hydrated with around 6.5H2O per cation, the [NPr4] salt apparently has a good metric match to the anion layer and is unsolvated, whilst the [NBu4] salt is intermediate and has EtOH and H2O in its cation layer, which is similar to the arrangement for the chiral [HSpa]+ cation. This family of salts shows highly organized chiral space and offers potential for the resolution of both chiral cations and neutral chiral solvent molecules.
螺硼酸阴离子,即 2,3,7,8-四羧酰胺基-1,4,6,9-四氧杂-5λ4-硼杂螺[4.4]壬烷,[B(TarNH2)2]-,来源于二元醇 L-酒石酰胺 TarNH2,[CH(O)(CONH2)]2,在其与烷基铵阳离子 [NR
4]+(R = Et、Pr 和 Bu)和石烷铵盐 [HSpa]+,其中的阳离子和阴离子是分离的。报告了四种此类盐的结构,即四丙基钛盐 C12H28N+-C8H12BN4O8
-、四乙基钛盐水合物 C8H20N+-C8H12BN4O8
--6.375H2O,四丁基钛盐的乙醇单溶液半水合物 C16H36N+-C8H12BN4O8
--C2H5OH-0.5H2O,以及作为乙醇单溶物的斯帕鎓(7-氮-15-氮杂十四烷环[7.7.1.02,7.010,15]十七烷)盐,C15H27N2
+-C8H12BN4O8
--C2H5OH。二维阴离子层保留了酰胺基团之间的分子间氢键,典型的度量重复约为 10 × 15 Å。与界面面积相匹配的约束条件将阳离子组织成截然不同的溶解排列,即[NEt4]盐高度水合,每个阳离子含有约 6.5H2O ;[NPr4]盐显然与阴离子层有良好的度量匹配,是非溶解的;而[NBu4]盐则处于中间状态,其阳离子层中含有 EtOH 和 H2O,这与手性[HSpa]+阳离子的排列相似。这一系列盐显示出高度有序的手性空间,为手性阳离子和中性手性溶剂分子的解析提供了潜力。