Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg i. Br., Germany.
Dalton Trans. 2010 Oct 7;39(37):8671-8. doi: 10.1039/c0dt00521e. Epub 2010 Aug 18.
The alkali metal salts (M = Li, Na, K, Rb, Cs) of the perchlorinated closo-dodecaborate B(12)Cl(12) were prepared by reaction of NEt(3)H[B(12)Cl(12)] with the corresponding alkali metal hydroxide. Crystallization of M(2)[B(12)Cl(12)] from liquid sulfur dioxide gave the sulfur dioxide complexes [Li(2)(SO(2))(8)][B(12)Cl(12)], Na(2)[B(12)Cl(12)].4SO(2), K(2)[B(12)Cl(12)].8SO(2), Rb(2)[B(12)Cl(12)].4SO(2), and Cs(2)[B(12)Cl(12)].SO(2), which were characterized by single crystal X-ray diffraction. In this work structurally characterized SO(2) complexes of the alkali metal cations K(+) and Rb(+) are reported for the first time. The structure of [Li(2)(SO(2))(8)][B(12)Cl(12)] contains discrete Li(2)(SO(2))(8) dications and B(12)Cl(12) dianions. Born-Haber cycles based on quantum chemical calculations and estimations of lattice enthalpies for the solid state explain the stability of the discrete dication Li(2)(SO(2))(8) in the solid state. Heavier alkali metals form three-dimensional networks containing metal-anion and metal-sulfur dioxide contacts. The crystal structures of Na(2)[B(12)Br(12)].8SO(2) and Na(2)[B(12)I(12)].8SO(2) were determined to investigate the influence of the halogen substituent on the anion. They contain similar three-dimensional network structures. Na(2)[B(12)Br(12)].8SO(2) is isostructural to K(2)[B(12)Cl(12)].8SO(2). In addition the crystal structures of the complexes Na(2)[B(12)I(12)].8SO(2).H(2)O and Na(2)[B(12)H(12)].6SO(2).2H(2)O, which contain water ligands, are reported as well. A comparison of halogenated dodecaborates B(12)X(12) (X = F, Cl, Br, I) based on small nu, Greek, tilde stretching frequencies of the corresponding Oct(3)NH[B(12)X(12)] (X = F - I) salts shows that the fluorinated anion B(12)F(12) is the least basic and the iodinated anion B(12)I(12) is the most basic anion in this series. These findings are in agreement with those for the corresponding series of perhalogenated carboranes and are explained by the polarizability of the halogen substituent.
碱金属盐（M = Li，Na，K，Rb，Cs）的过氯代笼状十二硼酸盐[B（12）Cl（12）]（2-）是通过[NEt（3）H]（2）[B（12）Cl（12）]与相应的碱金属氢氧化物反应制备的。M（2）[B（12）Cl（12）]从液态二氧化硫中结晶得到二氧化硫配合物[Li（2）（SO（2））（8）][B（12）Cl（12）]，Na（2）[B（12）Cl（12）]。4SO（2），K（2）[B（12）Cl（12）]。8SO（2），Rb（2）[B（12）Cl（12）]。4SO（2）和Cs（2）[B（12）Cl（12）]。SO（2），它们通过单晶 X 射线衍射进行了表征。在这项工作中，首次报道了碱金属阳离子 K（+）和 Rb（+）的结构特征为 SO（2）配合物。[Li（2）（SO（2））（8）][B（12）Cl（12）]的结构包含离散的[Li（2）（SO（2））（8）]（2+）二阳离子和[B（12）Cl（12）]（2-）二阴离子。基于量子化学计算的 Born-Haber 循环和固态晶格焓的估算解释了离散二阳离子[Li（2）（SO（2））（8）]（2+）在固态中的稳定性。较重的碱金属形成包含金属-阴离子和金属-二氧化硫接触的三维网络。Na（2）[B（12）Br（12）]。8SO（2）和 Na（2）[B（12）I（12）]。8SO（2）的晶体结构确定为研究阴离子取代基的影响。它们含有相似的三维网络结构。Na（2）[B（12）Br（12）]。8SO（2）与 K（2）[B（12）Cl（12）]。8SO（2）是同构的。此外，还报道了含有水配体的配合物 Na（2）[B（12）I（12）]。8SO（2）。H（2）O 和 Na（2）[B（12）H（12）]。6SO（2）。2H（2）O 的晶体结构。基于相应的[Oct（3）NH]（2）[B（12）X（12）]（X = F - I）盐的[N-H]伸缩频率对卤代十二硼酸盐[B（12）X（12）]（2-）（X = F，Cl，Br，I）进行比较表明，氟化阴离子[B（12）F（12）]（2-）是该系列中最不碱性的，而碘化阴离子[B（12）I（12）]（2-）是最碱性的阴离子。这些发现与相应的全卤代碳硼烷系列一致，并由卤代取代基的极化率解释。
