화학공학소재연구정보센터
Inorganic Chemistry, Vol.52, No.10, 5861-5866, 2013
Mixed Si/Ge Nine-Atom Zintl Clusters: ESI Mass Spectrometric Investigations and Single-Crystal Structure Determination of Paramagnetic [Si9-xGex](3-)
Mixed Si/Ge compounds are of special interest as potential materials for photovoltaic applications. In order to evaluate the usage of soluble precursor compounds, we investigated the synthesis of heteroatomic nine atom clusters that consist of Si and Ge atoms through dissolution of the ternary Zintl phases Ki(2)Si(17-x)Ge(x) (x = 9, 12) and Rb12Si17-xGex (x = 9). Electrospray ionization (ESI) mass spectrometry demonstrates the presence of mixed Si9-xGex clusters in acetonitrile solution. From ammonia solutions of the ternary phases, four compounds that contain 3-fold negatively charged [Si9-xGex](3-) clusters are obtained. The paramagnetic behavior is confirmed by EPR spectroscopy. [E-9](3-) Zintl clusters are considered as intermediate structures in the stepwise oxidation of [E-9](4-) clusters to novel element allotropes (E = Si Pb). The structure of Rb[Rb-crypt](2)[Si2.3(1)Ge6.7(1)](NH3)(7) and the isostructural structures of [Rb-crypt](3)[Si2.2(1)Ge6.8(1)](NH3)(8), [K-crypt](3)[Si2.4(1)Ge6.6(1)](NH3)(8.5), and [K-crypt](3)[Si4.6(1)Ge4.4(1)](NH3)(8.5) are investigated by single-crystal X-ray diffraction (crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]-hexacosane). The Si/Ge ratio of the products correlates with the composition of the ternary precursor phases.