s-Block chalcogenoether chemistry – thio- and selenoether coordination with hard Group 2 ions
作者:Paolo Farina、William Levason、Gillian Reid
DOI:10.1039/c2dt31692g
日期:——
A highly unusual series of Group 2 complexes with soft thio- and selenoether coordination, [MI2([18]aneO4E2)] (M = Ca or Sr; E = S or Se), [CaI2([18]aneO2S4)] and [MI2([15]aneO3S2)], has been prepared by reaction of anhydrous MI2 with the macrocycle in dry MeCN solution. The complexes have been characterised via1H NMR and IR spectroscopy, microanalysis and crystallographic studies which provide unambiguous confirmation of the MâS/Se coordination. The neutral complexes are seven- or eight-coordinate with the iodo ligands cis. The long MâE bond distances of â¼3.0 Ã
indicate weak interactions, but they are significantly less than the sum of the van der Waals radii for M and E, and are important in facilitating isolation of the complexes. Trace hydrolysis of [MI2([18]aneO4E2)] and [SrI2([15]aneO3S2)] leads, unexpectedly, to displacement of the iodo ligands rather than the S/Se donor functions, and the resulting dicationic [Ca(H2O)2([18]aneO4S2)]I2, [Sr(H2O)3([18]aneO4S2)]I2·H2O, [Sr(H2O)3([18]aneO4Se2)]I2 and [Sr(H2O)3([15]aneO3S2)]I2 complexes have been structurally characterised, forming eight- and nine-coordinate cations, with all the macrocyclic donor atoms coordinated. Reaction of Ca(CF3SO3)2 with [18]aneO4S2 in anhydrous MeCN solution similarly affords [Ca(CF3SO3)2([18]aneO4S2)], albeit in low yield, also proven crystallographically. Using the MI2 precursors provides a general entry into this area of coordination chemistry of these Group 2 ions, owing in part at least to their higher solubility in the weak donor (weakly competing) MeCN solvent. While CaCl2 reacts with 18-crown-6 either directly in MeCN giving [CaCl2(18-crown-6)], or in the presence of SbCl5 (to form trans-[Ca(MeCN)2(18-crown-6)][SbCl6]2), neither of these routes works with the oxa-thia or oxa-selena crowns.
通过无水 MI2 与大环在干燥的 MeCN 溶液中的反应,制备了一系列极不寻常的具有软硫醚和硒醚配位的第 2 组配合物 [MI2([18]aneO4E2)](M = Ca 或 Sr;E = S 或 Se)、[CaI2([18]aneO2S4)] 和 [MI2([15]aneO3S2)]。通过 1H NMR 和 IR 光谱、显微分析和晶体学研究对这些配合物进行了表征,结果明确证实了 MâS/Se 配位。中性配合物为七配位或八配位,碘配体为顺式。长达±3.0 Ã的MâE键距离表明它们之间的相互作用很微弱,但它们明显小于M和E的范德华半径之和,这对分离配合物非常重要。[MI2([18]aneO4E2)]和[SrI2([15]aneO3S2)]的微量水解出乎意料地导致了碘配体而不是 S/Se 供体功能的位移,并产生了二阳离子[Ca(H2O)2([18]aneO4S2)]I2、对[Sr(H2O)3([18]aneO4S2)]I2Â-H2O、[Sr(H2O)3([18]aneO4Se2)]I2 和[Sr(H2O)3([15]aneO3S2)]I2 复合物进行了结构表征,它们形成八配位和九配位阳离子,所有大环供体原子均配位。在无水 MeCN 溶液中,Ca(CF3SO3)2 与 [18]aneO4S2 发生反应,同样会产生 [Ca(CF3SO3)2([18]aneO4S2)],尽管产量较低,但也得到了晶体学证明。使用 MI2 前体为这些第 2 组离子的配位化学提供了一个普遍的切入点,至少部分原因是它们在弱供体(弱竞争)MeCN 溶剂中的溶解度较高。虽然 CaCl2 与 18-crown-6 可直接在 MeCN 中反应生成 [CaCl2(18-crown-6)],或在有 SbCl5 存在的情况下反应(生成反式-[Ca(MeCN)2(18-crown-6)][SbCl6]2),但这两种途径都不能与氧杂-硫杂或氧杂-硒杂冠发生作用。