Synthesis and Crystal Structure of δ-GeS2, the First Germanium Sulfide with an Expanded Framework Structure

Polycondensation of molecular adamantanoid [Ge₄S₁₀]⁴⁻ precursors at a remarkably low temperature (50°C) affords the crystalline binary dichalcogenide δ-GeS₂. Its crystal structure contains two interpenetrating cristobalite-like frameworks composed of adamantanoid [Ge₄S₆S_4/2] building blocks. Rings containing 24 atoms form the largest pores of each network (shown on the right).     

羧甲基纤维素钠辅助磁性Fe_3S_4纳米复合物的合成及其吸附与吸波性质研究

以羧甲基纤维素钠(CMC-Na)为模板,采用简单温和的水热法制备了一种薄片状含碳Fe3S4纳米复合物,并探讨了反应时间和反应温度的影响。采用X射线衍射、扫描电镜、透射电镜、FT IR、振动磁强计和UV-Vis对材料进行了表征。结果表明,这种纳米复合材料在常温下具有较好的吸波性质和对污水中亚甲基蓝染料的吸附作用。     

[Ge9{Si(SiMe3)3}2{Ge(SiMe3)3}]–: The Mixed Substituted Metalloid Germanium Cluster and the Intermetalloid Cluster [ZnGe18{Si(SiMe3)3}4{Ge(SiMe3)3}2]

The novel metalloid germanium cluster [Ge₉(Hyp)₂Hyp^Ge]^– ( 1 ) was synthesized, exhibiting two different bulky groups [Hyp = Si(SiMe₃)₃; Hyp^Ge = Ge(SiMe₃)₃]. Further reaction of 1 with ZnCl₂ gives the derivative [ZnGe₁₈(Hyp)₄(Hyp^Ge)₂] ( 2 ) in good yield, showing that the substitution of Si(SiMe₃)₃ by Ge(SiMe₃)₃ within a metalloid Ge₉R₃^– compound leads to a comparable reactivity. 1 and 2 are characterized by NMR spectroscopy, mass spectrometry ( 1 ) and single crystal structure analyses ( 2 ). 1 and 2 are the first metalloid germanium clusters bearing germyl groups.     

Electronic structure of the Fe3S4 cluster and its quasi-aromaticity

The localized molecular orbitals and their energy levels for the clusters [Fe₃S₄(SH)₃]^2–, [(HS)₃Fe₃S₄·Ni(PH₃)]^2–, [Mo₃S₄(OH₂)₉]⁴⁺, and [Mo₃S₄·Ni]⁴⁺ have been calculated by mean of the Edmiston-Ruedenberg energy localization technique under the CNDO/2 approximation in order to reveal the resemblance between [Fe₃S₄]⁺ and [Mo₃S₄]⁴⁺ in the geometrical configurations and the addition reactivities with heterometal atoms. It is shown that in these two cluster species with core {M ₃(₃-S)(-S)₃} of similar structure (M = Mo, Fe) there exist three synergically connected three-centered two-electron (M-S-M) -bonds around the puckered six-membered {M₃S₃} rings on account of delocalization of a lone electron pair on each bridging S atom; these (M-S-M) -bonds are thus capable of forming cubane-like heterometal clusters with intruder metal atoms through the ( M) bonding. It is therefore seen that unlike the [Mo₃S₄]⁴⁺ with appreciable bonding between the Mo atoms, the extra d-electrons on the metal atoms in the [Fe₃S₄]⁺ cluster are localized on the Fe atoms, exhibiting an electronic structure significantly different from that of the [Mo₃S₄]⁴⁺ cluster.     

Vibrational Spectra of Cluster Anions. 2. Vibrational Spectra of Compounds with the Cluster Anions [E4]4−: M4E4 (M = K,Rb, Cs; E = Ge,Sn) and β‐Na4Sn4

Vibrational spectra of the compounds M₄E₄ (M = K, Rb, Cs; E = Ge, Sn) and of β‐Na₄Sn₄ with the cluster anions [E₄]^4? were analysed based on the point group of isolated tetrahedranide units. The lower individual symmetry of the anions in the real structure being more patterned and complex primarily affects the spectra of the tetrahedro‐tetragermanides. ν₃(F₂) clearly splits both in Raman and IR and in the case of K₄Sn₄ only in IR. Rb₄Sn₄ and Cs₄Sn₄ exhibit very simple spectra with three bands in Raman and one band in IR. The breathing mode ν₁(A₁) for the quasi isolated [E₄]^4? cluster appears only in the Raman spectrum and is hardly influenced by the structural environment and by the nature of the alkali metal cations: ν₁(A₁) = 274 cm^?1 ([Ge₄]^4?) and 183‐187 cm^?1 ([Sn₄]^4?), respectively. The calculated valence force constants f_d(E–E) are: [Ge₄]^4? : f_d = 0.89 Ncm^?1 ( K ), 0.87 Ncm^?1 ( Rb ), 0.86 Ncm^?1 ( Cs ) and [Sn₄]^4? : 0.67 Ncm^?1 ( Na ), 0.66 Ncm^?1 ( K ), 0.67 Ncm^?1 ( Rb ), 0.68 Ncm^?1 ( Cs ). Both, the frequencies and the force constants fit well into the range previously reported.