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首页> 外文期刊>Zeitschrift fur Anorganische und Allgemeine Chemie >Vibrational spectra and quantum chemical calculations of the pure and mixed cluster anions [Si_xGe_(4-x)]~(4-) and [Ge _xSn_(4-x)]~(4-) (x = 0-4) in compounds with potassium and cesium
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Vibrational spectra and quantum chemical calculations of the pure and mixed cluster anions [Si_xGe_(4-x)]~(4-) and [Ge _xSn_(4-x)]~(4-) (x = 0-4) in compounds with potassium and cesium

机译：化合物中纯和混合簇阴离子[Si_xGe_（4-x）]〜（4-）和[Ge _xSn_（4-x）]〜（4-）（x = 0-4）的振动光谱和量子化学计算与钾和铯

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The Raman spectroscopic studies on samples with the starting compositions Cs_4[Si_2Ge_2] and M_4[Ge _2Sn_2] (M = K, Cs) verify unambiguously the presence of phases composed of the mixed cluster moieties [Si_xGe _(4-x)]~(4-) and [Ge_xSn_(4-x)]~(4-) (x = 1-3) including the pure anions [E_4]~(4-) (E = Si, Ge, Sn). The assignment of the vibrational frequencies is supported by normal coordinate analysis (NCA). The results for the mixed cluster anions are discussed in context with their isoelectronic analogs P_xAs _(4-x) (x = 1-3) and SbP_3. Using the characteristic breathing frequencies, one obtains for the ratio factor of the mixed moieties κ = ν([Si_xGe_(4-x)]~(4-)) / ν(P_xAs _(4-x)) = 0.79, which is in good agreement with the reported value of 0.77 for the pure cluster series [E_4]~(4-) (E = Si, Ge, Sn) and X_4 (X = P, As, Sb). The experimental average force constants f(Si-Ge) = 1.01 Ncm~(-1) and f(Ge-Sn) = 0.77 Ncm~(-1) correspond to arithmetic mean of those obtained for the pure anions in the binaries M _4E_4 (M = K, Rb, Cs; E = Si, Ge, Sn). The phonon frequencies of binary M_4E_4 (M = K, Cs; E = Si, Ge, Sn) and ternary K_4E_xE′_(4-x) (E, E′ = Si, Ge or Ge, Sn, E ≠ E′, x = 1, 2, 3) were calculated by using pseudopotential electronic structure method SIESTA. Excellent agreement between the calculated and experimental frequencies was obtained for the pure binaries. The theoretical results compare also well with experimental values for the mixed series [Si_xGe_(4-x)]~(4-), whereas for the corresponding mixed Ge-Sn species the differences between measured and calculated frequencies are greater than 10 %.
机译：对具有起始成分Cs_4 [Si_2Ge_2]和M_4 [Ge _2Sn_2]（M = K，Cs）的样品进行拉曼光谱研究，明确证实了由混合簇部分[Si_xGe _（4-x）]〜（ 4-）和[Ge_xSn_（4-x）]〜（4-）（x = 1-3），包括纯阴离子[E_4]〜（4-）（E = Si，Ge，Sn）。振动频率的分配由法向坐标分析（NCA）支持。在背景中讨论了混合簇阴离子的结果及其等电类似物P_xAs _（4-x）（x = 1-3）和SbP_3。使用特征呼吸频率，获得混合部分的比率因子κ=ν（[Si_xGe_（4-x）]〜（4-））/ν（P_xAs _（4-x））= 0.79，即与纯簇系列[E_4]〜（4-）（E = Si，Ge，Sn）和X_4（X = P，As，Sb）的报告值0.77高度吻合。实验平均力常数f（Si-Ge）= 1.01 Ncm〜（-1）和f（Ge-Sn）= 0.77 Ncm〜（-1）对应于二元M _4E_4中纯阴离子获得的算术平均值（M ＝ K，Rb，Cs; E ＝ Si，Ge，Sn）。二元M_4E_4（M = K，Cs; E = Si，Ge，Sn）和三元K_4E_xE'_（4-x）（E，E'= Si，Ge或Ge，Sn，E≠E'，通过使用伪电位电子结构方法SIESTA来计算x ＝ 1、2、3）。对于纯二进制文件，在计算频率和实验频率之间获得了极好的一致性。理论结果也与混合序列[Si_xGe_（4-x）]〜（4-）的实验值进行了比较，而对于相应的混合Ge-Sn物种，测量频率与计算频率之间的差异大于10％。

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