Structural Chemistry of Polyanion Clusters of p-Block Elements

通过穆斯堡尔谱学的研究，获得并促进了对Zintl化合物、碱金属或碱土金属与后过渡元素之间的金属间化合物以及相关化合物如Zintl阴离子的结构和键的认识。为了实现这一目的，已经进行了几次尝试;通过电化学方法进行了Zintl化合物的制备和Zintl阴离子的合成。在对反应条件进行了多次审查之后，Zintl化合物已经通过在氮气气氛下在铝坩埚中从含有化学计量量的碱金属和锑的熔体中结晶来制备。用该方法制备了K_3Sb、KSb、KSb_2、Na_3Sb、NaSb和Mg_3Sb_2二元化合物。在真空石英管中用熔体晶化法制备了锑与过渡元素的二元金属间化合物。用电化学方法制备Zintl阴离子的尝试失败了，<121>在20 K下测量了金属间化合物的穆斯堡尔谱，对M-Sb系（M = Na，K）化合物的穆斯堡尔谱表明，M_3Sb和Mg_3Sb_2是由M^+和Sb^+离子组成的离子型化合物<3->，其电子构型与金属间化合物的电子构型相同。而MSb和KSb_2的电子结构中，Sb原子间存在大量的共价相互作用，过剩电子主要集中在Sb的5 p轨道上。受电子数的顺序为MSb_2 &lt;MSb &lt;M_3Sb，表明这些化合物具有离子性。Cu_3Sb、Cu_2Sb、Ag_3Sb、AuSb_2和ZnSb的穆斯堡尔谱表明这些化合物是共价的。

This research have been done to obtain and promote the knowledge on the structure and bond in the Zintl compounds, the intermetallic compounds between the alkali or alkaline earth metals and posttransition elements, and the related compounds such as Zintl anions by means of Mossbauer spectroscopy. To perform this purpose, several attempts have been carried out ; the preparation of Zintl compound and synthesis of Zintl anion by a electrochemical method were carried out.After the many reviews of the reaction condition, the Zintl compounds have been prepared by the crystallization from the melt containing the stoichiometric amount of the alkali metal and antimony in an aluminum crucible under the nitrogen atmosphere. The binary compound K_3Sb, KSb, KSb_2, Na_3Sb, NaSb and Mg_3Sb_2 were prepared by this method. The binary intermetallic compound between antimony and the transition elements were prepared by the crystallization from the melt in a evacuated quartz tube. The attempt to prepare the Zintl anion by electrochemical method has been failed in spite of much effort.The ^<121>Sb Mossbauer spectra for the intermetallic compounds have been measured at 20K.The spectra for the compounds of M-Sb system (M = Na, K) shows that M_3Sb and Mg_3Sb_2 are an ionic compounds consist of the M^+ and Sb^<3-> ions, the same electron configuration as that of Xe. For MSb and KSb_2, on the other hand, much covalent interactions between antimony atoms are suggested and the excess electrons are mainly held in the Sb 5p orbitals. The order of the number of the accepted electrons are increased in the order MSb_2 <MSb <M_3Sb, indicating the ionic character of these compounds. The Mossbauer spectra for Cu_3Sb, Cu_2Sb, Ag_3Sb, AuSb_2, and ZnSb suggest the covalent nature for these compounds.