The compounds [Zn(tu)2(μ-fum)] 2 (tu = thiourea, fum = fumarate), [Zn(tu)2(μ-mal)] 3 (mal = malonate), [Zn(tu)2(μ-ipht)]·H2O 4 (ipht = isophthalate), [Zn(tu)2(μ-citr)] 5 (citr = citraconate), [Zn(tu)2(μ-pht)] 6 (pht = phthalate), [Zn(tu)2(μ-male)]·H2O 7 (male = maleate) and [Zn(tu)2(μ-hpht)]28 (hpht = homophthalate) have all been prepared from the reaction of [ZnCl2(tu)4] with the appropriate sodium dicarboxylate. Crystal structure determinations of the seven compounds demonstrate that in 2–7 bridging dicarboxylates link the zinc centres into polymeric chains, whereas in 8 bridging homophthalates lead to discrete dimers. Where permitted by the relative orientations of the carboxylates, the chains are linked together by pairs of N–H⋯O hydrogen bonds between thiourea NH groups and carboxylate oxygen atoms in a hydrogen bond donor–donor acceptor–acceptor (DD∶AA) arrangement. The hydrogen bonding patterns in the structure of 2 are very similar to those previously observed in [NEt4]2[fum]·2tu, suggesting that incorporation of zinc has little effect on the gross structure. The supramolecular structures of 5 and 6 are very similar to each other, and also to that of the previously reported compound [Zn(tu)2(μ-male)], which reflects the similar dispositions of the carboxylate groups. In contrast, the structure of 7 is very different, illustrating the dramatic effects that inclusion of solvent can have on the supramolecular structure.
化合物 [Zn(tu)₂(μ-fum)]₂ (tu =
硫脲,fum =
富马酸盐)、[Zn(tu)₂(μ-mal)]₃ (mal =
苹果酸盐)、[Zn(tu)₂(μ-ipht)]·H₂O₄ (ipht = 异苯二
甲酸盐)、[Zn(tu)₂(μ-citr)]₅ (citr =
柠檬酸盐)、[Zn(tu)₂(μ-pht)]₆ (pht =
邻苯二甲酸盐)、[Zn(tu)₂(μ-male)]·H₂O₇ (male =
马来酸盐) 和 [Zn(tu)₂(μ-hpht)]₂₈ (hpht = 同
邻苯二甲酸盐) 都是通过 [ZnCl₂(tu)₄] 与相应的
钠二
羧酸盐反应制备而成的。七种化合物的晶体结构测定表明,在 2–7 中,桥联的二
羧酸盐将
锌中心连接成聚合链,而在 8 中,桥联的同
邻苯二甲酸盐则形成离散的二聚体。在
羧酸盐的相对取向允许的情况下,这些链通过
硫脲 NH 基团与
羧酸盐氧原子之间的 N–H⋯O 氢键以氢键施受体 (DD:
AA) 的方式相互连接。化合物 2 中的氢键模式与之前观察到的 [NEt₄]₂[fum]·2tu 非常相似,这表明
锌的引入对整体结构影响不大。化合物 5 和 6 的超分子结构彼此非常相似,并且与之前报告的化合物 [Zn(tu)₂(μ-male)] 也十分接近,这反映了
羧酸盐基团的类似排布。相对而言,化合物 7 的结构则截然不同,体现了溶剂的引入对超分子结构可产生的显著影响。