Zusammenfassung
Dissolving the ternary material K6Rb6Si17 together with chelating ligands such as 18-crown-6 (1,4,7,10,13,16-hexaoxa-cyclooctadecane), dibenzo-18-crown-6 (2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) in liquid ammonia yields the solvates Rb4Si9 center dot 4.75NH(3) and [Rb(18-crown-6)]Rb3Si9 center dot ...
Zusammenfassung
Dissolving the ternary material K6Rb6Si17 together with chelating ligands such as 18-crown-6 (1,4,7,10,13,16-hexaoxa-cyclooctadecane), dibenzo-18-crown-6 (2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) in liquid ammonia yields the solvates Rb4Si9 center dot 4.75NH(3) and [Rb(18-crown-6)]Rb3Si9 center dot 4NH(3). Single-crystal X-ray diffraction analysis reveals the presence of Si-9(4-) anions, the existence of which in solution has been a matter of discussion until now. In both compounds, the Si-9(4-) cages display slightly distorted monocapped square-antiprismatic shapes. Additionally, quantum chemical calculations, NBO analysis and ELF (electron localisation function) considerations have been made to gain a deeper insight into the chemical bonding of this Zintl anion. The ELF analysis shows that, whereas the Wade-Mingos-Williams rules obviously apply for the prediction of the molecular shape of the anions, no evidence for three-centre two-electron bonding can be found. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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